Version 2.3 (1 Nov 2010) The Roncz Spreadsheets (EAA, 1989-1991) With notes, formatting and some additions by Duncan Meyer, Brisbane, AU These are the original 1990 spreadsheets written by John Roncz which I 1 How this workbook is organised: I have taken the eight separate Roncz spreadsheets and placed th I have renamed the individual sheets to indicate which EAA artic Color codes used: Personal data. Either from drawings, "Static" data - drawn from expereince Calculated cells - best not to fiddle 2 Summary of all sheets in this workbook Roncz8-Jan91 3 How to use these spreadsheets Read the first Roncz article (Nov '89), then examine the Roncz1- Enter your data into the GREEN cells Note the results as they appear in the RED cells - you will need Continue to the next Roncz article (Jan '90), and refer to the J When you arrive at the final sheet (Roncz7-MAIN-Aug) you should 4 I have embedded quite a few Notes and Tips for using these sheets. 5 Readme 6 I have added some behind-the-scenes calculations. These are comple . NB Read Intro2 for a step-by-step guide to using the Roncz Roncz1-Nov89: A convenient stand-alone spreadsheet, where you c Roncz2-Jan: Sizing wings, using claps, Lift, Flat plate area Roncz3-April: Referenced in the April PDF "Tail Incidence part 3 Roncz4-CG-May: This is where you enter all your component weight Roncz6-June: A stand-alone worksheet Roncz7-MAIN-Aug: The main spreadsheet [email protected]
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Version 2.3 (1 Nov 2010)
The Roncz Spreadsheets (EAA, 1989-1991)With notes, formatting and some additions by Duncan Meyer, Brisbane, AUThese are the original 1990 spreadsheets written by John Roncz which I have formatted for ease of use.Please read them in conjunction with his excellent series of articles.
1 How this workbook is organised:I have taken the eight separate Roncz spreadsheets and placed them in this self-contained multi-page workbook, so they are now all in one conveninet location.I have renamed the individual sheets to indicate which EAA article it is linked toColor codes used: Personal data. Either from drawings, measurements or wish-lists
"Static" data - drawn from expereince, rules-of-thumb, history etc.Calculated cells - best not to fiddle with these...
2 Summary of all sheets in this workbook
Roncz8-Jan913 How to use these spreadsheets
Read the first Roncz article (Nov '89), then examine the Roncz1-Nov89 spreadsheetEnter your data into the GREEN cellsNote the results as they appear in the RED cells - you will need these in later sheetsContinue to the next Roncz article (Jan '90), and refer to the JAN sheet (...etc)When you arrive at the final sheet (Roncz7-MAIN-Aug) you should have all the data you need.
4 I have embedded quite a few Notes and Tips for using these sheets. Hold your cursor over these bright yellow "Readme"s . Like the example below5 Readme6 I have added some behind-the-scenes calculations. These are completely optional, but they do make life a bit easier. They are clearly identified.
.NB Read Intro2 for a step-by-step guide to using the Roncz spreaddsheets
Roncz1-Nov89: A convenient stand-alone spreadsheet, where you can enter different speeds, altitudes etc, and get various dependent answersRoncz2-Jan: Sizing wings, using claps, Lift, Flat plate areaRoncz3-April: Referenced in the April PDF "Tail Incidence part 3"Roncz4-CG-May: This is where you enter all your component weights and moment arms PDF="Forward Sweep and the Great Crisis"Roncz6-June: A stand-alone worksheetRoncz7-MAIN-Aug: The main spreadsheet
Duncan: This is an example of an embedded note. When you see one, hover your cursor over it, and the contents will appear.
These are the original 1990 spreadsheets written by John Roncz which I have formatted for ease of use.Please read them in conjunction with his excellent series of articles.
I have taken the eight separate Roncz spreadsheets and placed them in this self-contained multi-page workbook, so they are now all in one conveninet location.
Personal data. Either from drawings, measurements or wish-lists"Static" data - drawn from expereince, rules-of-thumb, history etc.
I have embedded quite a few Notes and Tips for using these sheets. Hold your cursor over these bright yellow "Readme"s . Like the example below
I have added some behind-the-scenes calculations. These are completely optional, but they do make life a bit easier. They are clearly identified.
: A convenient stand-alone spreadsheet, where you can enter different speeds, altitudes etc, and get various dependent answers
: This is where you enter all your component weights and moment arms PDF="Forward Sweep and the Great Crisis"
Version 2.3 (1 Nov 2010)
A step-by-step guide to using the Roncz spreadsheets
WING INPUTSStep 1
Step 2You need to make some basic choices.
Step 3Probably one of the more critical choices you need to make is WHERE to place the wing. Too far forward will affect how your plane flies (or doesn't fly)
Step 4
Scenario: You want to design your own plane, but don't know where to start
Solution: The following notes refer to the new sheet, called "Basic Inputs" which I have created in order to bring together all the inputs required to design your airplane. There will be some back-and-forth between the other sheets, but essentially if you can provide all the inputs in the "Basic Inputs" sheet, you will be well on your way to designing your airplane. Follow these easy steps to completing the basic inputs required - you can find these on the sheet called "Basic Inputs"
Draw your plane as accurately as you can. Don't have high-end CAD software? Download a (free) copy of the Google "Sketchup" software from google.com CAD doesn't get easier (or cheaper) than this. Spend the time (maybe an hour or so) to learn how to use Sketchup. This is very much "entry level" CAD software, but it DOES allow you to draw accurate 2-D drawings with very little effort.
Choice 1: Stall speed (Vs). The stall speed is dependent on a number of things - eg: Wing area, lifting capacity of the wing (CL), and the weight of the aircraft. It's all a big trade-off. For example, the bigger the wing, the slower the stall, but your aircraft will have more drag, so it will fly more slowly. The inputs in the "Basic Inputs" worksheet will show you these trade-offs, and help you decide. Once you've chosen your stall speed, and you've estimated the weight of your airplane (flying weight that is - including you, fuel baggage etc - the Max All-up Weight), all you need to do is choose an airfoil and read off the maximum lift co-efficient (with flaps) at zero feet - you're on the ground, after all...
Choice 2: Wing Aspect Ratio (AR) The bigger the AR, the more efficiently your plane will fly. But as AR increases (for a given Sw) the shorter the chord (the wing will be longer and skinnier). And this means that the wing will also be thinner. And thinner means less height for your spar. And as spars become less deep, they lose strength very quickly, and you need to build them stronger (ie heavier). So now you have a trade-off between efficient wing and heavy wing. Rule of thumb: aim for an AR of somewhere between 6 and 9.Choice3: Airfoil thickness percentage (t/c). Usually about 15% but can be as low as 12% and as high as 18%
Together these inputs will feed into the "feedback" calculations in column E. Don't worry if these numbers don't make sense at the moment - they will. But you will need to make quite a few more entries before it all begins to come together. Change the stall speed and see how this affects the wing area. Change the MAUW and see what difference that makes. See how these changes affect the max speed, glide, slimb rates etc. Play with this till you're reasonably happy with your compromises. You can always change this later, so this isb't critical at this stage.
On the "Basic Inputs" sheet, you will see a yellow highlighted cell for this input. It is measured in INCHES rearward from your DATUM. I have used the prop bulkhead as my datum, but you can choose any datum you wish. Some people use the tip of the spinner - but then you can't change your spinner without having to recalculate your centre of gravity. Some people use the firewall. It's your choice.
To begin with, you will need to enter a number in this cell based on the eye-ball technique. Select a wing position which looks right - you will DEFINITELY be changing this as you progress, so it doesn't really matter what you choose now. But it helps to be in the ballpark...
Step 5
CENTRE OF GRAVITY inputsStep 6
PROPELLER inputsStep 7If you know what prop you're going to use, take your inputs directly from your prop. You will need to work out the cruise RPM and airspeeds
ENGINE inputsStep 8
Enter your engine HP, and the BSFC. Generally speaking a BSFC of about .45 is a good estimate for a modern engine. But if you have the exact numbers, enter them here
TAIL inputsStep 9
Airplane angle of attack) should be zero or nearly so. It makes sense (to me at least) to want your plane to fly level, not nose down or nose up. Hence I suggest zero is a good number…)
OTHER INPUTS
The Roncz4-CG-May sheet
The Roncz2-Jan sheet
The Rancz3-April sheet
Enter the tail moment arm. This should also be taken from your drawings. You measure the tail moment arm from wing MAC/4 to tail MAC/4 In English this means (1) calculate the wing Mean Aerodynamic Chord (MAC). On a rectangular, non-swept wing it is easy. Your MAC is your chord. For a swept wing or a tapered wing, things get a little more complex, but Roncz has provided the calculations to do this for you. You can find it on the Roncz3-April sheet (cell E19). (2) Now that you have your MAC, measure back 25% from the leading edge. ie if your chord is 48in, a quarter of 48 is 12, so mark 12 inches back from the wing leading edge. (3) Now do the same for the horisontal stabiliser.. (4) Finally, measure the distance between the wing mark and the h-stab mark. This is your tail moment arm.
The following three inputs (Design lift coefficient, Wing Drag Coefficient and CM of MAC Airfoil at the Design CL) need to be entered using data from the published data of your chosen airfoil. Which airfoil to use? This is very much a personal choice - but you really can't go wrong with using one of the Riblett airfoils. You will need to buy his little booklet (the only source of published data on his airfoils I know of) - but the booklet is cheap, and readily available from Aircraft Spruce.
Jump to the Roncz4-CG-May spreadsheet, and fill in the Fuselage Station (FS) and Waterline (WL) as well as the weights for all the listed items. Remember, the FS numbers are in INCHES back (ie tailwards) from your chosen datum. The WL measurements are from an arbitrary line also (most people use a line drawn horisontally through the propshaft. When you have filled in all FS and WL measurements, and estimated as best you can each of the weights, you will end up with two significant numbers: the CG of your aircraft as measured horisontally (B25), and vertically (C25) These numbers will automatically be copied back to your "Basic Inputs" sheet into cells E17 and E18
The first input (Horizontal Tail dCL/dAlpha) is not something you can guess. In fact, notice that it is in a RED cell - meaning that it is calculated elsewhere, and copied into this cell. Actually, now would be a good time to jump to another worksheet, and fill in the inputs there. Go to the Roncz3-April sheet, and copy into the green cells, the values you have decided on already. Notice the RED cells in row E These will be used again elsewhere. Now return to the Basic Inputs worksheet
The following four inputs (lines 36 to 39) can all be understood by reference to the original Roncz articles, which are referenced in the notes attached to each of the cells. Go off and read the articles, come back and fill in the four cells with sensible data.
Some of the Roncz spreadsheets are little more than stand-alone calculators to work out various things. However, the Roncz2-Jan sheet, Roncz3-April sheet and the Roncz4-CG-May sheet are critical. Take values you have already selected in your Basic Inputs sheet where neccessary.
This sheet allows you to calculate the CG as well as the weight of your airplane. Don't worry too much about being 100% accurate with the weights and positioning of each item. Give it your best shot, however, to ensure as accurate a result as possible. Don't worry too much about the weight of the cowl. I didn't. I simply included it in the weight of the fuselage shell itself.
This is a very important, and most interesting sheet. You should have most of the GREEN cell inputs already - except for those in cells D56 to D61 (the wetted areas). This in turn leads on to being able to calculate your equivalent Flat Plate Area, which has a number of important effects on how fast your plane will fly. I have included quite extensive notes at the bottom of that sheet to walk you through the process.
Again, easy inputs (you should have all of them worked out by now) leading to some critical calculated cells culminating in the recommended vertical and horisontal tail sizes. Bigger than this is OK, but not smaller.
FINALLY
First, there are some inputs at the top of the sheet to calculate the Aerodynamic Center Along the MAC.
Second, you will need to enter the inputs to calculate the Pitching Moments due to the Fuselage/Wing Combination. Read the "Readme" note for directions to the Roncz article dealing with these inputs.
You are now in a position to go to the main sheet - the Roncz7-MAIN-Aug sheet.
And that's it. Your goal is to see sensible numbers in the "Power on Neutral Point" section - rows 142 to 154. I have highlighted the critical lines in red. Bottom line, your Static Margin needs to be between about 5% and 20%. 5% will result in a very responsive, sporty plane. 20% will result in a stable, no-surprises aircraft. Anything less than 5% is probably going to be too sensitive, and towards the 20% limit, soo docile.
If your Static Margin falls outside these broad limits, you're in trouble, and it's back to the drawing board. So retun to the Basic Inputs sheet, and start fiddling. Notice that I have placed a number of calculated fields in col E. Of particular interest is the Static Margin and the Dynamic Stability Ratio. Fiddle with your aspect ratio, and the HS positioning of your wing. Both will alter these two numbers. Remember, if your Static Margin is too low, you won't be able to fly the plane. Too high is also bad. And then aim to get your stability ratio between generally acceptable limits as indicated on the sheet.
.
A step-by-step guide to using the Roncz spreadsheetsScenario: You want to design your own plane, but don't know where to start
Solution: Follow these easy steps…
Step 1
Draw your plane as accurately as you can. Don't have high-end CAD software? Download a (free) copy of the Google "Sketchup" software from google.com CAD doesn't get easier (or cheaper) than this. Spend th
A step-by-step guide to using the Roncz spreadsheetsScenario: You want to design your own plane, but don't know where to start
Solution: Follow these easy steps…
Draw your plane as accurately as you can. Don't have high-end CAD software? Download a (free) copy of the Google "Sketchup" software from google.com CAD doesn't get easier (or cheaper) than this. Spend th
Draw your plane as accurately as you can. Don't have high-end CAD software? Download a (free) copy of the Google "Sketchup" software from google.com CAD doesn't get easier (or cheaper) than this. Spend th
Aircraft Data Input sheetThis is your main sheet for inputting data, which will act as inputs on other sheetsInput all values in the green cellsOn the right (column E) are some calculated values, based on your inputs. Use these as a sanity check on the values you input
WINGDesired stall speed (kts) 45.0
718.60 327Wing Aspect Ratio 8.5
Airfoil t/c 0.15Leading Edge of MAC is at FS (in) 43.00
FS of Tail AC (in) 129.50Required V-tail Area (ft^2) 11.20
Vertical Tail Size (ft^2) 6.59
(Raymer: .035 to .065)
MaxCL (with flaps) - (From Roncz2)
E8
Duncan Meyer: Your choice - but compare other similar aircraft. The bigger the wing, the lower the stall speed, but the greqater the drag. As you fiddle with these inputs, check the calculated number in col E and adjust your inputs accordingly
E9
Duncan Meyer: Shorter span = larger chord =- thicker wing. This can be advantageous for building a strong wing. But it produces more drag, lower L/D numbers (ie the plane won't glide or climb as well
E12
Duncan Meyer: Needs to be greater than 2.5. Adjusting the Aspect Ratio will affect this, as will cell B12. The higher the number, the more stable the plane
E14
Duncan Meyer: From Roncz2-Jan Anything lower than 1.5 is probably good. Arnold's AR5 was less than 1 (See Roncz2-Jan for the details of how this is calculated)
E16
Duncan Meyer: Take this from your drawings. It is measured from 25% wing MAC to 25% tail MAC
E17
Duncan Meyer: These three calculated values come from From the CG worksheet (Roncz4-CG-May).
E20
Duncan Meyer: As far as airplane stability goes, this is the most important number of them all. You need to aim for something between 5% and 18% %5 represents a very "sporty" plane, 18% a very stable plane.
F37
Duncan: Reference: Roncz PDF "Wing Incidence and Tail Size", pg1, near top of col2. This value is calculated in the Roncz3April SS
Wing Span: 19 feet 4 inchesLength 15 feet 4 inchesCockpit Width: 24 inchesCockpit Height: 40 inches (curved canopy)Leg Room: 50 inches (firewall to seat back bulkhead)Fuel Capacity: 15 gallonsEmpty Weight: 430 poundsGross Weight: 800 poundsFuel: 90 Pounds (15 Gallons)Pilot Size: Up to 250 pounds - 6 foot 4 inches tallBaggage 30 pounds with 250 pound pilot. More if lighter pilot (within CG limits)
Engine:
Great Plains 1835 Volkswagen Conversion - Rated Takeoff Horsepower: 60
Performance: (Prototype 1) Measured by hand held GPS, the space between runway lights with 250 pound pilot and full fuel.
Takeoff Distance: 700 feetLanding Distance: 700 feetRate of Climb: 750 fpm @ 65 mph IAS (initial)Max Continuous Cruise: 130 mph using 3.5 gallons per hour. Range 400 miles with reserves.Economy Cruise: 100 mph using 2.5 gallons per hour. Range 500 miles with reserves.Top Speed: 145 mph
Plans: CAD drawn plans, Step by Step Photo Builder's Manual and Video. Full size templates. Projected availability Oshkosh 2007
Build Cost: $7000 including new Great Plains VW 1835. Build Time: 1500-2000 hours, from plans, less with prefabricated parts.
Beta Builders Program: 9 Experienced builders are currently checking plans and constructing aircraft.
How is it built? The PIK-26 uses wood construction, made largely from pine and from the Finnish birch that the country is famous for. I was once told that the reason it is so highly prized as a material is that the short summers and cold winters make the trees grow slowly, giving a tight and strong pattern of growth rings. The skins of the PIK-26 are made of birch plywood, with the thickness varying from 0.8 mm to 2.4 millimetres. The spars are made of pine, sawn from planks. Metal parts are made of 2024T3 aluminium and 4130 steel. It is said that if you can build a wooden model aircraft from plans, the PIK-26 is no problem. The wing ribs are made of 15 mm PVC foam, and use the GAW-2 profile. The time to complete all the wing ribs is about 8 hours. The total build time for the prototype was two years and 2,298 hours, and the 2nd PIK-26 took about 1,500 hours. The construction looks fairly typical for a light wooden monocoque.
Mike Arnold's AR-5 (213 mph on 65hp)
WING DRAG:
The aspect ratio eight, 55.125 square foot, low drag wing has a taper ratio of 0.78, a NACA 65/3-418 root airfoil, a NACA 65/2-215 tip airfoil, 50 percent span, 25 percent chord, flaps, and 44 percent span, 23 percent chord ailerons. The wing area exposed outside the fuselage is 49.6 square feet, and its wetted area is 102.6 square feet. At 207 mph at sea level the Reynolds number per foot of length is 1.94 million. The average chord is 2.7 yielding a wing Reynolds number of 5.15 million. The low turbulence wind tunnel data (1) gives a profile drag coefficient of 0.0047 for the root and 0.0045 for the tip. The resulting drag area for the exposed wing is 0.228 square feet. The slight losses due to turbulent wedges at the tips, roots and landing gear intersections, plus the slight discontinuity at the flap and aileron hinge lines will probably raise the average profile drag coefficient to 0.005, giving an exposed wing drag area of 0.248 square feet. The wing loading is 12 pounds per square feet, the dynamic pressure is 109.6 psf, giving a lift coefficient of 0.109. The induced drag coefficient is 0.00053, or induced drag area of 0.029 square feet.
FUSELAGE DRAG:
The 14.5 foot long, 23 inch wide, 35 inch deep fuselage has a length to effective diameter ratio of 6 and a frontal area of 5 square feet. Mike figured the wetted area from the plans and I figured it from measurements that Mike, my son Doug, and I made during the inspection. I cross-checked to within 1/3 of one percent of Mike's figure of 83 square feet. The canopy is 19.1 inches wide and protrudes 9.55 inches above the forebody.
Corby Starlet
Length: 4,8m / 15,5 ft.
Cocpit width: 0,6m / 24 in.
Gross: 300 kg / 662 lb.Stall: 65 km h-1 / 40 mphVne: 270 km h -1 / 166 mphCruise: 200 - 250 km h-1 / 123 - 151 mphRate of climb: 2 - 9 m s-1 / 387 -1935 fpmEngine: accetable hp range is 28- 80 hp.B-612 is originaly designed for Rotax 503 [50hp]
Performance: (Prototype 1) Measured by hand held GPS, the space between runway lights with 250 pound pilot and full fuel.
Max Continuous Cruise: 130 mph using 3.5 gallons per hour. Range 400 miles with reserves.
Plans: CAD drawn plans, Step by Step Photo Builder's Manual and Video. Full size templates. Projected availability Oshkosh 2007
Build Cost: $7000 including new Great Plains VW 1835. Build Time: 1500-2000 hours, from plans, less with prefabricated parts.
Beta Builders Program: 9 Experienced builders are currently checking plans and constructing aircraft.
How is it built? The PIK-26 uses wood construction, made largely from pine and from the Finnish birch that the country is famous for. I was once told that the reason it is so highly prized as a material is that the short summers and cold winters make the trees grow slowly, giving a tight and strong pattern of growth rings. The skins of the PIK-26 are made of birch plywood, with the thickness varying from 0.8 mm to 2.4 millimetres. The spars are made of pine, sawn from planks. Metal parts are made of 2024T3 aluminium and 4130 steel. It is said that if you can build a wooden model aircraft from plans, the PIK-26 is no problem. The wing ribs are made of 15 mm PVC foam, and use the GAW-2 profile. The time to complete all the wing ribs is about 8 hours. The total build time for the prototype was two years and 2,298 hours, and the 2nd PIK-26 took about 1,500 hours. The construction looks fairly typical for a light wooden monocoque.
The aspect ratio eight, 55.125 square foot, low drag wing has a taper ratio of 0.78, a NACA 65/3-418 root airfoil, a NACA 65/2-215 tip airfoil, 50 percent span, 25 percent chord, flaps, and 44 percent span, 23 percent chord ailerons. The wing area exposed outside the fuselage is 49.6 square feet, and its wetted area is 102.6 square feet. At 207 mph at sea level the Reynolds number per foot of length is 1.94 million. The average chord is 2.7 yielding a wing Reynolds number of 5.15 million. The low turbulence wind tunnel data (1) gives a profile drag coefficient of 0.0047 for the root and 0.0045 for the tip. The resulting drag area for the exposed wing is 0.228 square feet. The slight losses due to turbulent wedges at the tips, roots and landing gear intersections, plus the slight discontinuity at the flap and aileron hinge lines will probably raise the average profile drag coefficient to 0.005, giving an exposed wing drag area of 0.248 square feet. The wing loading is 12 pounds per square feet, the dynamic pressure is 109.6 psf, giving a lift coefficient of 0.109. The induced drag coefficient is 0.00053, or induced drag area of 0.029 square feet.
FUSELAGE DRAG:
The 14.5 foot long, 23 inch wide, 35 inch deep fuselage has a length to effective diameter ratio of 6 and a frontal area of 5 square feet. Mike figured the wetted area from the plans and I figured it from measurements that Mike, my son Doug, and I made during the inspection. I cross-checked to within 1/3 of one percent of Mike's figure of 83 square feet. The canopy is 19.1 inches wide and protrudes 9.55 inches above the forebody.
1. Valley Engineering Stock Redrive = 11.73 lbsa. Prop crush plate 6.1 ozb. Drive Belts (2.6 oz each X 2) 5.2 ozC. Mounting Hardware 6.0 ozd. Taper Bushing & hardware 5.35 oze. small pulley 13.4 ozf. Idler arm w/pulley 26.65 ozg. prop hub extension 15.1 ozh. prop drive shaft w/washer/nut 22.6 ozi. belt tensioner cam plate 10.85 ozj. large pulley w/ bearing 62.05 ozk. prop bolts 12.8 ozl. shaft shim washers 1.55 oz
2. Stock pulse fuel pump 4.65 oz
3. Complete intake w/carb 88.25 oz
C2
Duncan: Notes: FS = Fuselage station. Measured in inches from the datum Datum = An arbitrary point along the fuse. I have used the spinner backing plate. Some people use the firewall. Others, the tip of the spinner. Forward of the Datum is -ve, rearwards is +ve WL = "Waterline" A vertical reference line (the datum is a horisontal reference line) Many people use the prop shaft (ie centre of the prop) as the WL. You could use the ground. Your choice. Above the WL is +ve, below is -ve Important These weights need to be accurate. Together they make up the total weight of your plane This weight is used frequently to calculate other things
B30
Duncan: Your airplane's horisontal CG is this many inches back from the Datum
C30
Duncan: This is the vertical CG, as measured from your waterline. +ve means above the WL, -ve means below it
D30
Duncan: This weight is used in many other places in this workbook. Make every attempt to get this as accurate as possible.
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4. Alternator magnets 32 oz
Other...
Engine block without flywheel, alternator, carb/intake. Starter installed =70.2 lbs
Engine block without flywheel, alternator, carb/intake, starter = 62.15 lbs
Notes... I have managed to literally carve the engine weight down to 100 lbs,which was my goal to keep my aircraft 103 weight compliant with the Big Twinfrom Valley Engineering. I know I couldtake quite a bit further, but for now I've met goal. Elimination of the starterand implenting an ignition system to allow hand proping will be next on my list,but for now I am out of time to further experiment. Some of the things I didwere...
1. Drilled lightening holes in big pulley2. Drilled lightening holes in idler arm3. Drilled lightening holes in belt tension cam4. Carved excess material from redrive mount plate5. Ground off all casting marks, cooling tin mounts, valve cover lettering,etc....6. Removed alternator magnets, coils and wiring/hardware.7. Drilled lightening holes in flywheel (yes, I rebalanced)8. Removed stock pulse pump - don't need it, my airframe has sufficientgravity feed system.
I plan to use a lipo battery as used in RC aircraft to start the engine usingthe stock starter system. Lipo batteries are VERY light weight and have thepunch to kick the starter right over... a 10 oz lipo should give many, manyreliable starts, be quick disconnect also.... AND for less than the price of astandard lead acid battery...
Just my 2 cents folks, take it for what its worth to you. My modifications aretruely EXPERIMENTAL and I do not suggest or imply that anyone try what I haveuntil I have some significant time put on this engine/modifications. If you dotry any of my modifications, you accept FULL responsibility for your ownactions.
Sincerely,Doug Hart
Part I ........
Hi Folks,
Here's some very good numbers on the weights of various parts on the Generac.I used a precision digital scale, calibration checked just before weights were
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taken.
Cooling tin:
1. Rh Cylinder top 4.55 oz2. LH Cylinder top 4.4 oz3. RH Cylinder - middle 8.2 oz4. LH Cylinder - Middle 8.1 oz5. Fan Cover 4.9 oz6. Fan Guard 16.5 oz7. Fan 16.65 oz8. Lower Center, aft 13.7 oz9. Aft Outer cover 46.7 oz10. Attach Hardware-all 8.75 oz
Total: 132.45 oz or 8.278 lbs
Starter, attach hardware and associated wiring: 128.8 oz or 8.05 lbs
Flywheel (with ignition magnets and alternator magnets) 18 lbs
Alternator coil,attach hardware and associated wiring: 4.64 lbs
Some observations and other findings....
The ignition has a come-in speed of 300 rpm. It IS IMPOSSIBLE to hand propthe engine to this speed. A different ignition system will have to be used inorder to eliminate the electric start or to be able to hand prop start. I amVERY interested in this option! I don't mind hand proping when I can save 8 lbson a starter and probably another 8 to 10lbs for a battery!
The alternator coils/hardware would be very easy to remove, but then noelectrical for the aircraft. As it is, it is a 30 amp alternator, which isWAAAY more than I will ever need. I'm looking at reducing this to a 3 or 5 amp. Ibelieve 2 or so lbs could be saved with this option.
The flywheel is Very heavy... the starter gear ring is cast in as part of theflywheel. I do think that some weight could be removed by the use of"lightening" holes on the face of the flywheel. Using 1" diameter holes, evenlyspaced, I estimate at least 6 lbs weightsavings, but this will require a machine shop (or someone with the right tools)to complete and rebalance the flywheel. If ignition system could be upgradedfor hand proping, the ring gearcould be cut off also. Of course, the best, and probably most expensivesolution would be an aluminum machined flywheel, I'd bet with proper design,could get all up weight to around 9 or 10 lbs…
The Stock carb that comes on the engine is ABSOLUTELY no good for aircraftuse. It does not have an accelerator pump and will hesitate, even stall theengine if sudden power demand is input!
The stock fuel pump (pulse type) is adequate for maybe a 12 inch lift, but
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absolutely no more. The Fuel tank should be kept in line or higher than theengine. Another option is to use electric pump to be ableto place tank anywhereyou want.
I think the best place to start mods/lightening would be with the starter andignition systems.
I currently have my oldest Generac (with just under 350 hours total time) downto 112 lbs w/electric start and alternator still on.
I would really like to loose at least 10 more lbs so that my aircraft can havesome extra useful load! I believe 20 lbs would be possible, but I think costwill really start going up at this point.
It's good to get back to this discussion. I had been looking at thenew B&S 810cc vertical as a possible way to get more cc's for the sameweight as the B&S 26 hp. Because of the difference in weight betweenthe Generac "Big Twin" and the small block B&S, I had assumed theGenerac was a "big block" as well. Sooooo I went to visit a smallengine builder/supplier, who happens to be an automotive engineer. Icame armed with my checkbook and intended to to buy an 810cc block andtry to stroke it somehow. I came home with a lot of information and aGenerac engine and parts.
First of all, he demystified the numbers on the Generac. They selltwo engines, both of which can be had vertical or horizontal:
The GTH 760 has a 90mm (3.54") bore and a 78mm (2.36") stroke.
The GTH 990 has a 90mm (3.54") bore and a 60mm (3.07") stroke!
But here is the secret. The GTH 990 has a dished piston to keepit's compression low enough to not detonate on regular fuel. By usingthe GTH760 engine with it's FLAT TOP piston and a GTH 990 crank, you geta 998cc engine with a 9.5:1 compression ratio. This is the engine thatGenerac sells for LP Gas, however, the Generac Engineers say that youcan run it on higher octane gasoline at 3800 RPM .................ALLDAY! Guess what I took home.
Another little factoid, There are two standards to report engineperformance. J1955 is the standard that measures the engine torque andHP with ALL the accessories attached as sold. J1940 is the measure ofperformance with least restrictive intake and exhaust and noaccessories. EVERYONE uses J1940, therefore, our applied results mayvary and any comparison to real time measurement are skewed.
`The long stroke Generac GTH 990 with FLAT TOP pistons makes 44hp @ 3800rpm continuous. It makes 66ft/lbs of torque at 3000 rpm. These areJ1940 figures. I believe this is the Valley Engineering "Big Twin".
Now to the issue of weight. There are three grades of SAE ratingfor small engines. Consumer, Commercial, and Industrial.....The Generacis Industrial. The above 998cc engine can safely be run at 4000rpm and3800 continuous. The difference between the small block B&S and the
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Generac, which has a very similar block, is in the components. I wasshown both crank and rods. The difference is startling. The heads hadbigger valves and "D" shaped intakes. These are all places where theweight is worth the increase. The other big differences are in theflywheel, fan, shroud.
I appreciate your work on weight reduction. I agree that thestarter and associated electricals are a great place to go. My interestin in the possibility that a redrive can be built with a dampener thatwill allow the prop to be used as flywheel inertia and we can loseanother ten pounds. I am also going to try to mount the redrive on theflywheel side. This will place the exhausts downstream, put all the"flywheel" weight on one end. and allow us to cut a huge chunk of shaftoff the back.
HP 100.00BSFC 0.45 (Raymer Homebuilt, p18). Substitute with known value if you have it
Endurance (hrs) 4135.60 This number has been transferred to cell D15 for you…
152.7272727
84.55 kg Aircraft fuse only186.00 lbs348.00 lbs Aircraft with engine
H17
Duncan: In order to work out how much your fuel will weigh, you need to know the HP of your engine, its BSFC (if you don't know it, try using .45 as a reasonable number for modern engines) and your planned flight endurance. Excel then adds an extra 30 mins reserve, and uses these inputs to work out the weight of your fuel. Enter this weight into cell D15
HP 50.0BSFC 0.45 (Raymer Homebuilt, p18). Substitute with known value if you have it
Endurance (hrs) 4.0067.8 This number has been transferred to cell D15 for you…
152.7272727
72 kg Aircraft only157.7 lbs
H247
Duncan: In order to work out how much your fuel will weigh, you need to know the HP of your engine, its BSFC (if you don't know it, try using .45 as a reasonable number for modern engines) and your planned flight endurance. Excel then adds an extra 30 mins reserve, and uses these inputs to work out the weight of your fuel. Enter this weight into cell D15
Wash hands with vinegar, then soapWash brushes in vinegar then add lots of detergentOr wash brushes in acetoneUsed brushes are best - they don't shed hairFillers: CabosilGood bonds - cotton flox - but best is sandwiching two glass tapes between the bonded partsMolding - use playdough
Main gear calculationsAlpha degrees 12Alpha radians 0.20943951023932Tan (alpha) 0.21255656167002Height from CG (mm) 968Fwd from CG vertical (mm) 205.754751696581From datum (mm) 953.85
CF vs Glass (Marske)5.7oz twill CF = 10oz glass 5.7oz/yd^2 = 193g/m^2, 10oz = 234g/m^2Thickness of laminate = 2x its weight for CF, 1.5x weight for glassWeight of laminate = .015 x fabric weighteg: 1x lams 5.9oz CF = 5.9x.015 = .088lbs/ft^2 (1.4oz) or... 200g/m^2 = 3g/m^2CF lam = 2x strength of glass lam of same thicknessCF lam = 4x stiffer than glass lam of same thickness20oz glass lam minimum (ie 2x 5.7oz CF is equivalent)
Mike Arnold: AR-5 Video #2 "How its made"Uses the Marske method for bonding bulkheads to the fuse, after micro under the bulkheadUses 36-grit/80-grit sanding boardLaminate = 2x UNICanopy = 1/10 inch plexiglass. Blown. Base = glass sandwich.Flap gap = 1/16 to 1/32 inch gapUses styrofoam, 2lbs/cu ftVideo = 1:20 - the good stuffFlap control bellcrank is inside the body, behind an inspection panelHardpoints = plywood with nuts and washers on the back side. Bonded to the foam coreCentral foot or so of leading edge of flap removedHard points bonded, then false spar added. Then foam replaced, leaving hard point area freeAluminium angle bonded to foam cores as base for hingesRudder: 1.28.01Ailerons: cable operated (3/32 inch wire) to am aileron bellcrank and pushrod1:31:40 Main landing gear. Bolted (4 bolts) to the wing spar.1:32:00 Landing gearWheels 4" diam 410/4.00 tyre Off BD-4Urethane foam for the fuel tank - fuel resistantCover entire airframe with micro/epoxy, and sanded smoothThen covered with polyester primer (sprayed on). Then sanded, and painted with Imron polyurethane
Wengine mounts. Brackets (4 bolts) on pilot side of firewall.Firewall = 1/4" plywood, with extra 1/8" plywood at the engine mount brackets1:39:45Bracket = 1/8" aluminum, four bolts sensibly within the perimiter at the cornersFuel tank 1:41:001/4" clark foam. Top: glass one side, bend in place glass 2nd sideKX99 Bendix King radioStick Controls: 1:44:30Wing construction: 1:46:004x ribs used
Orion re: Balsabalsa is a firewall material sandwiched between triaxial glass and protected with a Silica fire blanket
(Need to apply load distribution to these calculations)
Carbon Fibre Monarch - some notesMaterials: 5.7oz CF TWILL. 2x layersRibs laid out over corrugated plastic (flat with narrow risers)D-tube mold - Laser-cut? Then fit in 1x CF Twill and 1x Glass twill vacuum bag. Difficulty getting CF to conform to mold - hence the glassfibreD-tube - drill out most of the flat area. Smaller hole at front, larger at rear almost to edges, maybe 1/2inch between themPhenolic bushings for all fibreglass to CF fittingsLayup of spar: CF on plastic sheet. Add resin. Add 2nd plastic sheet. Work with squeegee till saturated. - then remove top layer plastic, lift and turn upside down into spar mold. - Vacuum bagging essential to get good carbon fit.Ribs:Marske: 5.7oz CF + 6oz Glass, Basically solid flat sheet with 3-D depressions. Vacuum bagged in laser cut (CNC) molds
Metric:
Marske: used 8-10in vacuum for the ribs. Lip folded over for extra stiffnessMarske: main rib = .75ozMarske: Ribs made from male foam molds, a layer of epoxy, polished and PVA - then covered with CF and vacuum baggedMarske: Cure vacuum bagged parts for 1 week before removing from mold
BeLite:CF ribs in wooden style. Flat sheet cut in water cutter
Razorback: Ditto. 2x 5.7oz LAMS @ .65 ft^2 each = 0.115lbs/rib. Ribs @ 9", so, 22 ribs Total weight: 2.53lbs
Perhaps the most amazing fact is that construction time is considerably reduced by utilizing this process. When all of the parts for the wing are ready, the entire wing can be set up, bonded (glued) and ready for covering in 3 days from start to finish. Construction of the wing is a simple process. It involves taking two pre-formed wing spars which have been created from carbon fiber and sliding 7 ribs over them. The spars simply slip through holes
SC-1 Minisport
Colomban's LucioleWooden spar + foam ribsMmmmmA very slow plane... So maybe OK
Razorback:Marske method: 3-D CF rib vacuum bagged in mold, with stiffening strips. Aiming for 15g per rib = 300g
How much static thrust is required?Orion:
Norman:
Orion:
Two part wing uses GA 37U-A315 airfoil. It consists of composite main spar with carbon caps on which are glued ribs made of extruded polystyren. It is covered with 1 mm plywood. Wingtips are made of extruded
Several fixed pitch props I've seen used for
Typically general aviation engine/prop If you want to do a really rough guesstimate
Control linkages - various sourcesSide stick http://www.homebuiltairplanes.com/forums/aircraft-design-aerodynamics-new-technology/8873-side-mounted-stick.html
I used a side stick on my Sgian Dubh with a gate bolt action to a steering column knuckle straight to the elevator horn. Since it is a flying wing the aileron controls were atached to this tube by a short lever. The leg room is much more comfortable and the nose is better streamlined.
For my design I'm (for the moment) also using a sidestick. This has several advantages:*Less wide fuselage (you need at least 5" between your knees, compared to none for a sidestick)*Much easier setup.*No mechanisms under your seat. Gliders typically have a mess of wires, push-pull tubes and other stuff running under the seat. Making it massive (crunch-able foam) makes a lot of sense to me from the crash-worthiness perspective.
I'm aiming for a single (carbon) tube on the right side, mounted in a tunnel. It should slide forward and aft and rotate for roll. The nice thing about this is that it's not only simply, but it's fairly simple to make an adjustable stick too (it's just an extension to the carbon tube). That's a great feature single arm length greatly varies between individuals and sidestick can be VERY critical to that.
As for control feel; I've flown various gliders with parallelogram steering (the stick doesn't rotate, put only "slides" forward and aft). Feels great and you don't have G-induced pull-up. As for roll, during thermalling I usually flew those gliders with two fingers above/around the stick and two below, thus rotating your fist results in roll. Very comfortable and much more natural, compared to moving your whole hand. Low stick forces are required though.
Side sticks are sexy, but to make the control throws short enough and forces low enough, you have to work with really small control moments. The nice flying birds with side sticks, well, they have pretty small control surface chords and high aspect ratio surfaces and foils. Get out TOWS, and check it out. Flap chord is squared. On the other end of the scale, the Unlimited acrobatic birds, with great big balance horns on the rudder and elevators and huge spades on the ailerons still use center sticks and big throws.
Start with your desired control throws and stick forces, work through the mechanical advantage to your control surfaces, and that will give you your necessary control surface moments. Then you have to play with your control surface area and chord to get to reasonable control surface moment coefficients. Yes, you can work with balance horns and pivot the surfaces fairly well aft on the surface (both place area ahead of the pivot to reduce moments) but if you play near or beyond 75% aero balance, you are also playing near aileron snatch. So there are practical limits on how low you can get your moments... Which might drive you right back to a center stick.
I used a side stick on my Sgian Dubh with a gate bolt action to a steering column knuckle straight to the elevator horn. Since it is a flying wing the aileron controls were atached to this tube by a short lever. The leg room is much more comfortable and the nose is better streamlined.
For my design I'm (for the moment) also using a sidestick. This has several advantages:*Less wide fuselage (you need at least 5" between your knees, compared to none for a sidestick)
*No mechanisms under your seat. Gliders typically have a mess of wires, push-pull tubes and other stuff running under the seat. Making it massive (crunch-able foam) makes a lot of sense to me from the crash-worthiness perspective.
I'm aiming for a single (carbon) tube on the right side, mounted in a tunnel. It should slide forward and aft and rotate for roll. The nice thing about this is that it's not only simply, but it's fairly simple to make an adjustable stick too (it's just an extension to the carbon tube). That's a great feature single arm length greatly varies between individuals and sidestick can be VERY critical to that.
As for control feel; I've flown various gliders with parallelogram steering (the stick doesn't rotate, put only "slides" forward and aft). Feels great and you don't have G-induced pull-up. As for roll, during thermalling I usually flew those gliders with two fingers above/around the stick and two below, thus rotating your fist results in roll. Very comfortable and much more natural, compared to moving your whole hand. Low stick forces are required
Side sticks are sexy, but to make the control throws short enough and forces low enough, you have to work with really small control moments. The nice flying birds with side sticks, well, they have pretty small control surface chords and high aspect ratio surfaces and foils. Get out TOWS, and check it out. Flap chord is squared. On the other end of the scale, the Unlimited acrobatic birds, with great big balance horns on the rudder and
Start with your desired control throws and stick forces, work through the mechanical advantage to your control surfaces, and that will give you your necessary control surface moments. Then you have to play with your control surface area and chord to get to reasonable control surface moment coefficients. Yes, you can work with balance horns and pivot the surfaces fairly well aft on the surface (both place area ahead of the pivot to reduce moments) but if you play near or beyond 75% aero balance, you are also playing near aileron snatch. So there are practical limits on how low you can get your moments... Which might drive you right back to a center stick.
How to calculate your airplane's total wetted area, and its equivalent flat plate area. This is a "bonus" section - but drawn from the Roncz articles.
You will need to calculate your airplane's wetted area. Roncz (see "Sizing Wings", pg4, col1 bottom ) gives you a great method on how to estimate the FUSE wetted area. Eter your fuse wetted area in cell D56 below.
What this section on the right does is to ease the pain of working out the rest of the plane's wetted area. Enter your best guess for the H-stab and Vertical tail areas in cells D57 and D58.
The WING's wetted area is based on the airfoil % thickness, span and MAC. Select your airfoil % thickness (cell D59), enter the span and the MAC, and your WING's wetted area appears in cell D66
Finally, based on trike or tail dragger undercarriage, enter the wetted area for the undercarriage in cell D63.
Your aircraft's total wetted area now appears in cell D64
Now, depending on your construction type, you're able to calculate your equivalent flat plate area. Simply multiply your total wetted area by the drag counts per square foot, based on the table on the right.
B1
Duncan: This is an important feeder sheet to the MAIN sheet. Do not be over-optimistic regarding the wing CL max. It is seldom as high as we'd like. The Roncz numbers, for instance,seem overly optimistic
B6
Duncan: This is where you select your wing span. This is not a calculated field - you get to choose... You also get to choose your favorite cruise altitude
B10
Duncan: Check at the bottom of this sheet for rules-of-thumb for this cell
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Fuse wetted area (ft^2)V-tail wetted area (ft^2)H-tail wetted area (ft^2)Wing airfoil % thickness
Wing span (ft)Wing MAC (in)
Wing wetted areaLanding gear wetted area
TOTAL
Composite - above averageComposite - very clean
Calculating wing Clmax with flapsClmax clean 1.50
Correction for tip losses 1.42Flap span (% span) 0.50
Flap chord (% of chord) 0.30Flap ext (% of chord) 0.30
You will need to calculate your airplane's wetted area. Roncz (see "Sizing Wings", pg4, col1 bottom ) gives you a great method on how to estimate the FUSE wetted area. Eter your fuse wetted area in cell D56 below.
What this section on the right does is to ease the pain of working out the rest of the plane's wetted area. Enter your best guess for the H-stab and Vertical tail areas in cells D57 and D58.
The WING's wetted area is based on the airfoil % thickness, span and MAC. Select your airfoil % thickness (cell D59), enter the span and the MAC, and your WING's wetted area appears in cell D66
Finally, based on trike or tail dragger undercarriage, enter the wetted area for the undercarriage in cell D63.
Your aircraft's total wetted area now appears in cell D64
Now, depending on your construction type, you're able to calculate your equivalent flat plate area. Simply multiply your total wetted area by the drag counts per square foot, based on the table on the right.
How to calculate your airplane's total wetted area, and its equivalent flat plate area. This is a "bonus" section - but drawn from the Roncz articles.Wing wetted area table (Roncz approximation)
Duncan: Sizing your Wings (Jan) - pg6, col1 half way down.
F21
Duncan: See Roncz Sizing Wings PDF, pg5, top col3
F25
Duncan: What we have here is a "gift" from Roncz - it gives you a convenient way to estimate the flat plate area of ANY aircraft - just so long as you have access to its published performance numbers.
F29
Duncan: Reference: Sizing your Wings (Jan) - pg6, col2 last para
H36
Duncan: Col B shows CL max values as estimated by Roncz (65% span) Col F takes into account real-world 3-D effects However, both are estimates, so substitute known values (in col B) for your airfoil if you have them. Then check out the size of wing you would need with the chosen type of flap.
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61.2 A reasonable estimate can ge had by taking the average of the TOP and SIDE areas, and multiplying by 3.148.5 Approx 2.1*plan area0.0 (Included in fuse area) Approx 2.1*plan area. Roncz suggests 25% of wing area as a ballpark figure
15%20.1928.5098.80
25193.53 ft^2
Drag counts per ft^2Metal - round rivets 0.0065 See Roncz Sizing Wings PDF, pg4, bottom col2
Metal - flush rivets 0.006Composite - general 0.005
Composite - above average 0.0048Composite - very clean 0.0045
D56
Duncan: From your drawings.
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CL max with 3-D effects of finite span, tip vortex etc taken into account
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A reasonable estimate can ge had by taking the average of the TOP and SIDE areas, and multiplying by 3.14
(Included in fuse area) Approx 2.1*plan area. Roncz suggests 25% of wing area as a ballpark figure
0.821428571
15.60714286
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Spreadsheet #3 From Sport Aviation2-90 JGR
ReadmeSpeed (kts) 170
Speed (mph) 60Altitude: 1000
Cruise Weight: 669Wing Area sq. ft. 48
Wing Span, ft. 20Sweep, degrees 6.3
Max CL 2.19
Chord @BL0 (in) 28.5 Remember, BL0 = the aircraft centrelineAngle for zero lift (deg) -1.00 Get from published airfoil data
Root Chord, inches 41.9Tip Chord, inches 15.5
HORIZONTAL TAILLever arm, inches 79.4
Volume coefficient 0.65 Raymer recommends between .45 and .65
VERTICAL TAILLever arm, inches 79.4
Volume coefficient 0.045 Raymer recommends between .035 and .065
From roncz4-CGFrom Basic Inputs
From Basic InputsFrom Basic InputsFrom Basic Inputs
From Basic Inputs
From Basic Inputs
From Basic Inputs
B3
Duncan: These six green cells are all you need to concern yourself with. Enter realistic values in these cells, and the rest of the sheet is automatically calculated for you...
Chord in Fuselage: 51.29Distance from Trailing Edge to AC of Tail: 58.0
Wing Root Chord (in): 28.5Wing Tip Chord (in): 28.5Wing Area (ft^2): 48.0Wing Span (ft): 20.19Distance from Wing AC to Tail AC (in): 79.4Design Lift Coefficient: *** 0.300Wing Lift Curve Slope dCL/dAlpha: *** 0.087 Get from Roncz3-April spreadsheetDynamic Pressure at Design Point (Q) *** 99.323 Get from Roncz2-Jan spreadsheet (Q)
Mean Aerodynamic Chord (in): 28.5Downwash at Tail (degrees): 1.30dEpsilon/dAlpha: 0.3742
Pitching Moments due to Fuselage (ft-lbs) 1577.65 Foot-PoundsdCM/dCL of Fuselage: 0.4648
***Pitching Moments due to Wing Airfoil***
CM of MAC Airfoil at the Design CL: *** 0.012Pitching Moments due to Wing: 135.78
***Pitching Moments due to Center of Gravity***
FS of Center of Gravity (in): *** 45.65
C2
Duncan: This is the main sheet. All other sheets feed into this one Even so, there are some green cells here also. Refer to the Roncz PDF files indicated till you fully understand them
E6
Duncan: Get these from the published numbers for your airfoil.
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Waterline of Center of Gravity (in): *** 0.90FS of Aerodynamic Center (in): 50.13Waterline of Aerodynamic Center (in): 0.00Wing Drag Coefficient: *** 0.0055
Wing Drag, Pounds: 26.20Wing Lift, Pounds: 1429.08Pitching Moments due to Wing Lift (ft-lbs) -532.64Pitching Moments due to Wing Drag (ft-lbs) -1.98Total Moments about the CG due to Wing (ft-lbs) -398.83Moment Coefficient CM, cg wing: -0.0352
***Propeller Normal Force***
Propeler RPM: 3200.0Prop Diameter (in): 64.0Average Blade Width (in): 5.0Airplane Flate Plate Drag (sq. ft.): 0.929Airplane Max Speed (MPH): *** 212.5Number of Blades: 2.0Distance from Prop to CG (in): 1.0
Duncan: Reference: Roncz PDF "Tail Incidence part 2", pg2, col3
E108
Duncan: Reference: Roncz PDF "Wing Incidence and Tail Size", pg1, near top of col2
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Required tail Area:(ft^2) 12.07Fuselage Station of Tail Aerodynamic Center (in) 129.50Power Off Dynamic Pressure Ratio at Tail: 0.80 Readme
Uncorrected Power-Off Neutral Point is at FS (in) 60.69Correction for Fuselage (in) -13.25Power off Neutral Point with Fuselage (in aft of datum) 47.44
***Propeller Induced Downwash***
Thrust Coefficient: 0.00408Value of Ribner Curve "A": 0.00246Value of Ribner Curve "B": 0.25311dCNp/dAlpha for Zero Thrust: 0.00133dEpsilon, prop/dAlpha: 0.00280dCM/dCL Due to Propeller Downwash: 0.00060Propeller Downwash Moves Neutral Point (in) -0.01709
***Normal Force Contribution***dCM/dCL due to Normal Force: 0.00054Propeller Normal Force Moves Neutral Point (in) -0.01549
***Thrust Line Offset Contribution***
Perkins and Hage "K" Factor: 0.00083dCM/dCL due to Thrust Line Offset: 0.00219Thrust Line Offset Moves Neutral Point (in) -0.06
***Propwash Over Tail Contribution***
Extra "Q" Over Tail Moves Neutral Point (in) 0.44
***Power On Neutral Point***
Power Off Neutral Point (in) 47.44Corrected for Propwash (in) 47.42Corrected for Normal Force (in) 47.41Corrected for Thrust Line Offset (in) 47.34Corrected for Tail Dynamic Pressure due to Prop (in) 47.78
Final Power On Neutral Point is At FS (in aft of datum) 47.78Leading Edge of MAC is at FS (in) 43.00Neutral Point is at (% of the MAC) 16.78Center of Gravity is at (% of the MAC) 9.31Static Margin is (% of the MAC) 7.47
***Total Pitching Moments About the CG***
Due to Fuselage 1577.65Due to Wing Airfoil Section 135.78Due to Wing Lift vs CG Location -532.64Due to Wing Drag vs CG Location -1.98Due to Propeller Normal Force 2.09
E111
Duncan: Reference: Roncz PDF "Tail Incidence part 3, pg3, col3, bottom para1
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Due to Thrust Line Offset 6.96
Total Moments About the CG (ft-lbs) 1187.87
***Tail Incidence for Zero Elevator***
Tail Lift Required (lbs) 170.01Tail Lift Coefficient Required 0.17Incidence Required for Zero Elevator (deg) 3.260 Readme
***Elevator Required to Trim***
Tail Incidence Selected (deg) -1.30 ReadmeElevator Area/Tail Area (%) 100.00 ReadmeWing CL with Level Fuselage *** 0.300
Airplane Angle of Attack 0.00Tail CL per Degree of Elevator Deflection -88.2149Tail CL at the Selected Incidence Angle -0.2249Elevator Deflection Required to Trim (deg) -0.0045
***Ground Effect***
Tail CL in Ground Effect -0.169Elevator Trim Required to Trim in Ground Effect -0.004
E171
Duncan: Reference: Roncz PDF "Tail Incidence part 4", pg4, bottom col1
E175
Duncan: Reference: Roncz PDF "Tail Incidence part 4", pg4, col2
E176
Duncan: Reference: Roncz PDF "Tail Incidence part 4", pg4, col2, middle
Spreadsheet for calculating basic lift parametersfrom Sport Aviation ReadmeJGR 11-89Given...H (altitude) 0.0 rho (density) 0.00237689V (knots) 42.0 V (ft./sec) 70.938W (weight) 675 V (MPH) 48.384
If you know this... Calculate this...CL (lift coef) 2.34 S (wing area) 48.234
If you know this... Calculate this...S (wing area) 50.0 CL (lift coef) 2.257339
If you know this... Calculate this...S (wing area) 50.0 V (knots) 88.249CL (lift coef) 0.511300
E2
Duncan: The first thing you must do in designing your plane, is to select a wing area Your reference for this spreadsheet is the original Nov'89 EAA article (Roncz PDF "Designing your homebuilt") Pay particular attention to pg 3, col 3, half way down
Fuel allowance (%) 6 Wf/Wo with allow.Empty Weight constant "a" 0.92603478231Weight - crew 81.8 180Weight - Passengers 0.0 0Weight - payload 4.5 10 See Sizing Graph sheet for Wo Results
Wing taper ratio 0.5 Wing SpanWing LE (ft from datum pt) 582.3 1.91 Root ChordCG as % of MAC FWD 28% Tip Chord
REAR 29% Mean Chord (C-bar)
Aer
od
ynam
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H-Stab LE from datum 2461.00 8.07 Spar depth
H-Stab chord 685.50 2.25
H-Stab quarter chord 171.5 0.56
H-Stab 1/4 chord from datum (Xtail) 2632.5 8.64 Stability numbers
H-Stab tail arm 1794.9 5.89 Spar position (from datum)
H-Stab span 2423.0 7.95 Sht (h-stab)
Wing 1/4 chord from datum (Xwing) 837.6 2.75 Svt (tail)Wing LE to H-Stab LE 1878.7 6.16 AR (h-stab)Cht (volume coeff) 0.8 CGVertical tail arm 1794.9 5.89 % of MACCvt (volume coeff) 0.05 Static MarginTip of spinner to datum 1291.00 4.24Wfuselage 609.50 2.00 Main gear pos from datum (12%)Lfuselage 4745.00 15.57 CG movement (full/empty gas)Kdownwash 0.5 Average CG
L/D cruise
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Clmax clean 1.5 GA37A315
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D10
duncan: Raymer Homebuilt p90 Split flaps, 60% chord Based on numbers in C56
C16
Duncan: BMW K75 engine = 185lbs, 73hp $3500 NZD Big Twin = 112lbs, 40hp $6880 NZD (includes prop) Solo Flight = 88lbs 40hp $8231 NZD prop extra Hummel 1/2 VW = 84lbs, 45hp $7430 NZD
Duncan: Datum = firewall This is how far the LE is from the datum
B37
Duncan: Can't remember the source for this, but read somewhere that CG should be between 22 and 34 % of MAC back from the wing LE) This does not quite line up with Raymer's calcs down at rows 79, 80
D47
Duncan: Arbitrary - but chosen on the large side of Raymer's guidelines as advised by Orion. Raymer Homebuilder pg 36
D49
Duncan: Arbitrary - but chosen on large side of Raymer's guidelines. Raymer Homebuilder p36
D53
Duncan: 5% is normal for a low wing. Less for a t-tail. Going with .5 (Raymer College text)
Win
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Correction for tip losses 1.425 Approach speedFlap span in % span 0.6Flap chord % of chord 0.4Flap ext in % of chord 40% StallDelta Cl-max plain 0.9 Plain
Main gear pos from datum (12%) 620.5CG movement (full/empty gas) 1.1
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W
ref
wetfeD S
SCC 0
AAK
424.0
75.0
1
DL
cR
fp
bhp
eWW /5000 975.01
000 1 WWWW
WWW
FE
payloadpeople
09.000aWWWE
L11
Duncan: Formula approximation from Raymer Homebuilders Ed (pg ??) Basically, a cylinder with radius = the average of top and side x length
L13
Duncan: Based on actual measurements. The 4.92 is the square area of the wing cross section. Multiply this by the actual wing exposed length (ie span minus fuselage width)
duncan: Drag due to lift factor used to determine drag Raymer Homebuilt p18
L26
duncan: Raymer's fudge factor to account for fuel burn at takeoff
K32
Duncan: Raymer's estimation seems way off. His formula is =H14*H29 I'm basing my fuel on known consumption for the K75 (12 l/hr). Four hours = 48 litres = 10 gall
Duncan: Raymer's estimation seems way off. His formula is =H14*H29 I'm basing my fuel on known consumption for the K75 (12 l/hr). Four hours = 48 litres = 10 gall
K36
Duncan: Raymer: =K32/6
55 kts63 mph
101 kph42 kts48 mph
78 kph
NB It all boils down to the Stability Numbers (F42)
Equations (from book) Misc Useful Calcs
q
KSW
SW
qCD
L
D //
1
0
2
2
1StallVq
LqCS
W
ref
wetfeD S
SCC 0
AAK
424.0
75.0
1
DL
cR
fp
bhp
eWW /5000 975.01
000 1 WWWW
WWW
FE
payloadpeople
09.000aWWWE
Climb, Cruise, & Max Speed Calculations for Simplified Aircraft Design for HomebuildersUse this sheet for performance calculations after you have drawn your design and measured its geometry.
V kts V ft/sec CL50 84.45 0.44038166 0.59 180.597987 144.47839 7.755835219 1.85673063
If these velocities are too slow or too fast you can change them, but you must have only 5 velocities
D5
Using Power Coefficient from Sheet 3. Include adjustments for scrubbing drag and other propeller losses (see book).
H5
At takeoff weight Wo
Climb, Cruise, & Max Speed Calculations for Simplified Aircraft Design for HomebuildersUse this sheet for performance calculations after you have drawn your design and measured its geometry.
Wo guess We/Wo We Wo calculated200 0.2612 52.2 298.2250 0.2560 64.0 295.8300 0.2518 75.5 293.9350 0.2484 86.9 292.3
If sizing graph lines do not cross, change Wo-guess values above.
Enter Wo from graph (lbs) 295Pick engine with horsepower of at least: 92
Power of Selected Engine: #REF!Calculated Power Loading: #REF!
Pick Wo from graph, where the two lines cross. Enter this value below to find the minimum horsepower engine for your power loading.
Now find a suitable engine of at least this horsepower and enter its power below:
Now go to sheet 1 and enter the power of your selected engine and the power loading calculated above in the boxes this color. 180 200 220 240 260 280 300 320 340 360
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Sizing Graph
Wo Guess
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Wo Guess
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Landing gear design spreadsheetWritten by Neal Willford 1/24/04 for Sport AviationBased on methods presented in "Design of Light Aircraft" by Richard Hiscocks, "The Landing Gear" by Herb Rawdon and "Analysis and Design of Flight Vehicle Structures" by BruhnFor SOLID, round tapered cantilever spring gear with single deflectionGear drag load is accounted for in bendingThis spreadsheet is for educational purposes only and may contain errors. Any attempt to use the results for actual design purposes are done at the user's own risk.Input required in yellow cells
Gear Geometry ( see Figure )Gear span: 21.58 inchesGear height: 20.00 inchesGear side view depth (positive aft): 6.00 inchesDist. from leg bend to wheel C/L: 3.50 inchesLeg length in mounting socket: 8.00 inchesGear diameter at side of fuselage: 1.38 inchesGear diameter at axle: 0.77 inchesGear leg true length = 30.03 inches
Landing Gear Capability. Margin of Safety should be at least 0.50 for Limit Energy Condition.Limit Reserve Max vertical landing speed =
Energy Energy Max vertical landing speed =Condition Condition Aft component of gear load, K =
Vertical gear load per wheel (lbs) 1468 1643 Tire deflection at limit energy conditionGear drag load per wheel (lbs) 367 411 Tire deflection at limit energy =Gear load factor (ng) 4.1 4.6 Max. possible tire deflection =Limit inertial load factor (n) 4.8 5.6Tire + gear vertical deflection (in) 7.6 8.5Combined Margin of Safety 0.84 0.64Drop height (inches) 13.9 20.1Effective weight for drop test (lbs) 550 505% of load of on main wheels at gross weight and C.G. while a/c sitting on the ground:Main wheel tire + gear leg deflection while a/c sitting on the ground =Additional gear + tire deflection for reserve energy condition =
Background calculationsGear leg deflection constant calculation assumes that the gear leg has constant area from end of leg to wheel center line
Section Local area I slopeM Dia (inches) sq. in. in^4 M/EI
constants for E and load = 1Angle of gear leg from horizon =
Gear Leg Deflection constant = 164324 Limit energy drop ht =
Gear Stub Deflection constant = 530 Multiplier if drag load in bending =
Energy required and available calculationsGear load factor (ng) 0.9 3 5Vertical load per wheel (lbs) 323 1078 1796Tire deflection (inches) 0.46 1.54 2.57Load normal to gear leg (lbs) 249 829 1381Deflection of gear normal to leg (inches) 1.4 4.7 7.8Deflection due to gear stub (inches) 0.2 0.7 1.1Total gear leg deflection (inches) 1.6 5.4 9.0FAR vertical sink speed (ft/sec) 8.7 8.7 8.7Energy due to sink speed (in-lbs) 5017 5017 5017Energy due to gear and tire stroke (in-lbs) 200 666 1110Total limit energy of landing (in-lbs) 5217 5683 6127Reserve energy (in-lbs) 7225 7225 7225Energy absorbed by tires (in-lbs) 70 782 2173Energy absorbed by gear legs (in-lbs) 201 2231 6197Total energy provided by gear (in-lbs) 271 3013 8371Total gear + tire deflection 1.67Torsion moment on gear leg due to sweep and drag load =
Based on methods presented in "Design of Light Aircraft" by Richard Hiscocks, "The Landing Gear" by Herb Rawdon and "Analysis and Design of Flight Vehicle Structures" by Bruhn
This spreadsheet is for educational purposes only and may contain errors. Any attempt to use the results for actual design purposes are done at the user's own risk.
Material properties of some materials used for gear legsinches Ultimate Modulus Materialinches strength Elasticity Densityinches Material Ftu (psi) E (psi) (lbs/in^3)psi 4340, 5160 and 6150 Steel 220000 29000000 0.286
2024-T3 Aluminum 70000 10500000 0.0986AL-4V Titanium 130000 16000000 0.160*** Steel Ftu are heat treated values ***Gear Leg Material PropertiesModulus of elasticity, E: 29000000 psiUltimate tensile strength, Ftu: 220000 psiMaterial density: 0.286 lbs/in^3Approx gear weight = 24.9 lbs
Max vertical landing speed = 8.7 ft/sec (for limit energy)Max vertical landing speed = 10.4 ft/sec (for reserve energy)Aft component of gear load, K = 0.25Tire deflection at limit energy conditionTire deflection at limit energy = 2.10 inchesMax. possible tire deflection = 2.70 inches
90 %1.67 inches6.81 inches
calculation assumes that the gear leg has constant area from end of leg to wheel center line tapered gear slope = 0.0201476875max Mr/I = 166 187189 209425 Min M.S. =