Simviation Forum - 1st design started: XS1

Aug 14^th, 2012 at 9:11pm

wahubna Offline
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I have ever intention of designing and producing my own sport aircraft designs. With that said, even though I am just about to start my senior aeronautical engineering classes, I have officially started my 1st design.

I am dubbing it 'XS1' (Experimental Single-seat #1). What is shown below is the layout for the tubing that will form the fuselage. I am going with an old-school style of construction after seeing how rugged and cheap this technique can be on the WACOs and Great Lakes. Thus the fuselage frame will be steel tubing (probably 4130 Chromoly), tube sizes are something I am currently investigating.

This airplane will be a single seat tail dragger with a single low wing. The engine currently being used for reference is the Lycoming IO-360. My ultimate goal is to produce an aircraft reminiscent of a early WW2 era fighter with either an open or closed cockpit (or semi-enclosed like many early/pre WW2 fighters).
Skin will thus be a mix of aluminum sheet and fabric with some sheet metal and wooden bulkheads and fuselage formers like the WACO YMF5 and Great Lakes.
I am planing on making the seat in a fairly reclined position (shooting for ~20degrees) to give that 'go-fast' feel as well as for comfort. Avionics will be the usual stuff you see in small single seaters of today.

Please note, I have done 0 stress analysis thus far; this represents the very beginning of my project. I hope to make this my senior design project in school as well. So periodically I will post screen shots of progress as the design grows.

engine:
http://www.lycoming.textron.com/engines/series/pdfs/360ci%20Engine%20Insert.pdf

tube sizing being investigated:
http://www.cartesiantube.com/documents/tubesizes.pdf#view=Fit

Serious suggestions are welcome!
Tailwinds,
Adam

‎"At that time [1909] the chief engineer was almost always the chief test pilot as well. That had the fortunate result of eliminating poor engineering early in aviation."- Igor Sikorsky

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Reply #1 - Aug 15^th, 2012 at 12:49am

Splinter562 Offline
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Looks like fun. My senior design project was a ton of work but a lot of fun. It's pretty rewarding to go from initial hand sketches to "Hey.. I think this thing could actually work."

It is good to see you are looking at what other people have done to solve problems similar to yours. That is a big step in the right direction and it's a step that a lot of people miss both in school and in industry. At lot of successful designs I've seen can be described as "This is basically the same thing they do on the ______" or, more often "It's kinda like a cross between the _____ and the _____".

Unless it is going to be an acro machine, the IO-360 might be a bit much for a single place LSA. The Carbon Cub has what is basically an O-360 and only just makes it under the wire as an LSA and only with a bit of hand-waving. Yours would probably still be a great performer with an O-320.

SolidWorks is a fantastic software package for mechanical design. If you've got the Simulation license, than analyzing that tube frame will be a piece of cake. Kinematics is also a strong suit for SolidWorks, especially if you've got the Motion license, but you probably won't get into that in your senior design class. Modeling the wings might get a little interesting in SolidWorks. Yours will probably end up being pretty simple, so it actually might not be too bad.

Good Luck,
- Brian

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Reply #2 - Aug 15^th, 2012 at 5:26am

wahubna Offline
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Splinter562 wrote on Aug 15^th, 2012 at 12:49am:

Looks like fun. My senior design project was a ton of work but a lot of fun. It's pretty rewarding to go from initial hand sketches to "Hey.. I think this thing could actually work."

It is good to see you are looking at what other people have done to solve problems similar to yours. That is a big step in the right direction and it's a step that a lot of people miss both in school and in industry. At lot of successful designs I've seen can be described as "This is basically the same thing they do on the ______" or, more often "It's kinda like a cross between the _____ and the _____".

Unless it is going to be an acro machine, the IO-360 might be a bit much for a single place LSA. The Carbon Cub has what is basically an O-360 and only just makes it under the wire as an LSA and only with a bit of hand-waving. Yours would probably still be a great performer with an O-320.

SolidWorks is a fantastic software package for mechanical design. If you've got the Simulation license, than analyzing that tube frame will be a piece of cake. Kinematics is also a strong suit for SolidWorks, especially if you've got the Motion license, but you probably won't get into that in your senior design class. Modeling the wings might get a little interesting in SolidWorks. Yours will probably end up being pretty simple, so it actually might not be too bad.

Good Luck,
- Brian

Thanks Brian!
Im actually staying away from ever doing LSAs, as it has been told to me numerous times: "there is no money in it". When you build a 'cheap' plane you really have to go cheap to make it sell, but then you cant make enough money off of it to pay for production and development.
I have the student license for Solidworks 2012 with a year license with access to several more licenses. Problem wit that is the student version is frustratingly absent of the 'weldment' library of tubes.

I have done 2 complete UAVs in Solidworks already, so I am actually okay with wings. I use 'XYZ curve' with coordinates found from an online airfoil library. Usually these coordinates take a bit of editing before they import okay.
Although I am going to do a tapered wing, so I will have to find the chord length of each airfoil and scale them.

For analysis I was thinking of using some analysis software available at school. Im planing though on doing something completely against what is taught in engineering courses today: Im going to over-build it....*GASP*! We are taught to always always always 1st and foremost above all other things: optimize the structure's stress. Personally, I feel safety and reliability is worth the extra material. WACOs are overbuilt, and I have read many and heard many stories of WACOs getting balled up but the occupants walking away after dusting themselves off. I want mine to be just as safe.

‎"At that time [1909] the chief engineer was almost always the chief test pilot as well. That had the fortunate result of eliminating poor engineering early in aviation."- Igor Sikorsky

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Reply #3 - Aug 15^th, 2012 at 8:15pm

wahubna Offline
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Layout with wings and tail surfaces outlined. A box showing area of the current engine being investigated is also shown...I upped the size a bit Wink

As I said earlier, Im looking to make a plane that looks and feels like a warbird, hence the power.

‎"At that time [1909] the chief engineer was almost always the chief test pilot as well. That had the fortunate result of eliminating poor engineering early in aviation."- Igor Sikorsky

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Reply #4 - Aug 16^th, 2012 at 3:38pm

Jayhawk Jake Offline
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Wichita, KS

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wahubna wrote on Aug 15^th, 2012 at 8:15pm:

Layout with wings and tail surfaces outlined. A box showing area of the current engine being investigated is also shown...I upped the size a bit Wink

As I said earlier, Im looking to make a plane that looks and feels like a warbird, hence the power.

[img]

What have you done in the way of stability and weight analysis? I can tell you right now your wing is too small and too far forward.

Are you following any design process? I'd recommend that if you are truly serious about designing a functioning airplane you follow either Roskam's method or Dan Raymer's methods. Roskam is how I learned, but I've utilized Raymers book in the past.

I'll be glad to follow along and offer you some advice along the way, and maybe for some 'inspiration' if you or anyone else would like I'll make a post about Aethos, the batshit crazy plane I designed in college

AMD Athalon X6 1090T 3.2Ghz::EVGA nVidia GeForce GTX 560Ti 2GB GDDR5::8GB RAM
*The opinions expressed above are my own and are in no way representative of fact or opinion of any other person, corporation, or company.*

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Reply #5 - Aug 16^th, 2012 at 4:16pm

Fozzer Offline
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An elderly FS 2004 addict!
Hereford. England. EGBS.

Posts: 24861

Don't forget those wise words in your signature, Adam...>>>

"At that time [1909] the chief engineer was almost always the chief test pilot as well. That had the fortunate result of eliminating poor engineering early in aviation."- Igor Sikorsky

..be very afraid!.... Shocked

...!

Paul....I like Mattress Testing...its much closer to the ground... Grin

...

...!

Dell Dimension 5000 BTX Tower. Win7 Home Edition, 32 Bit. Intel Pentium 4, dual 2.8 GHz. 2.5GB RAM, nVidia GF 9500GT 1GB. SATA 500GB + 80GB. Philips 17" LCD Monitor. Micronet ADSL Modem only. Saitek Cyborg Evo Force. FS 2004 + FSX. Briggs and Stratton Petrol Lawn Mower...Motor Bikes. Gas Cooker... and lots of musical instruments!.... ...!
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Reply #6 - Aug 16^th, 2012 at 6:13pm

wahubna Offline
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Paul, I remember those words every day and I am dead serious about following them.

Jake, I have designed a few aircraft by the way that flew well Wink

Just smaller.... Wink

At any rate, as I said in the original post, I am just starting, cant do analysis with no numbers! I am taking the preliminary design stage all the way through until I have skins on it so I can do useful analysis rather than computative guess work. The wing area is actually pretty proportional to what was done on WW2 figthers when compared with fuselage length. The wings are no more 'too far forward' than the Spitfire's. If you recall, that aircraft had its wing positioned very far forward. The 2 aircraft which sparked this idea was the Globe Swift/LoPresti Fury and the NXT racers (in particular Relentless and Nemesis.

The wing is comfortably far forward considering there will be probably 600lbs around the nose. The current engine choice is a hefty 444lbs; JUST the engine. That is not including the firewall, mount, associated bracketry, pipping, etc. The engine mount structure will add the most of any other single item.

All avionics and fluid tanks will be forward of the pilot. The pilot will be situated near the trailing edge of the wing (again, much like warbirds). So with the big engine (bigger than one in a Mooney 201's I might add), all the fluids, and associated hardware at the leading edge and FORWARD with a heavy weight concentrated several feet forward of the leading edge, being tail heavy will not be the problem.

About the wing area being too small, the wing area is just about perfect for my wishes. I do not want yet another aerobatic aircraft. It wont be a bush plane either nor a 'business' plane. Again, its a poor man's warbird. Which reminds me, comparing the wing span to length it is still better than a Bf-109E! I remember reading several places that outsiders of Douglas were adamant that the A-4 was too small...wow did it prove them wrong! Cool

There are plenty of home-builts with bigger wing areas (proportionally) but they usually have odd airfoils optimized for speed (Midget Mustang comes to mind). I should add there that this thing is not optimized for fuel burn or "efficiency". It will be a warbird at heart optimized only for nostalgia and fun.

I have found wing span to length is a simple proportion that is a good 'rule of thumb' as long as the AR of your design is similar to the planes it is being compared to. Mine is comparative to most WW2 planes in AR, so I looked at a dozen ranging from the I-16 to Bf-109. The 109 having the lowest (hence its poorer turning abilities), the I-16 the highest (stellar maneuvering but horrible stability: to short).
I have verified this rule of thumb and its limits by studying real aircraft and looking at R/C airplanes as well. So far it works well...until the design becomes 'abnormal' like a pusher or delta wing.

THIS is what a 'too small and too far forward' wing looks like Wink

....

but dang its fast!
http://aircraftimages.net/display.php/Nemesis_4990

Every aircraft designer has their own tastes and with aircraft, there are an infinite number of ways for that to show through.

Top view

At any rate, I welcome the critiquing, it forces me to think over things again which is very important. I will and DO consider all serious thoughts (such as Jake's) and I hope more people offer some input. Im not expecting to win everyone over though, you can find fault in just about every design for one reason or another.

One thing I would really like some input on is the canopy styling. Seems pointless but it will point me in the direction of how I should shape the fuselage and consequently the rest of the aircraft. I HATE canopies that seem to bulge or stick out, the lines need to flow from nose to tail dang it!
Smooth
http://www.eaa.org/news/2012/2012-04-13_tecnam.asp
Smoother
http://www.eaa.org/news/2012/2012-04-19_aero-panthera.asp
curvy but smooth
http://www.eaa.org/news/2012/2012-04-05_diamonda52.asp
BULGE!
http://www.eaa.org/news/2012/2012-02-16_aerochia.asp

Personally I like this style for looks and because it is geometrically simple:
http://www.simmerspaintshop.com/forums/f29-aircraft-profile-painting/fw-190-a4-w...
Yep, that would be a Fw-190 Cool

Another plane with relatively small wings placed far forward.

‎"At that time [1909] the chief engineer was almost always the chief test pilot as well. That had the fortunate result of eliminating poor engineering early in aviation."- Igor Sikorsky

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Reply #7 - Aug 16^th, 2012 at 9:04pm

Jayhawk Jake Offline
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Wichita, KS

Gender:
Posts: 483

wahubna wrote on Aug 16^th, 2012 at 6:13pm:

Paul, I remember those words every day and I am dead serious about following them.

Jake, I have designed a few aircraft by the way that flew well Wink

Just smaller.... Wink

At any rate, as I said in the original post, I am just starting, cant do analysis with no numbers! I am taking the preliminary design stage all the way through until I have skins on it so I can do useful analysis rather than computative guess work. The wing area is actually pretty proportional to what was done on WW2 figthers when compared with fuselage length. The wings are no more 'too far forward' than the Spitfire's. If you recall, that aircraft had its wing positioned very far forward. The 2 aircraft which sparked this idea was the Globe Swift/LoPresti Fury and the NXT racers (in particular Relentless and Nemesis.

The wing is comfortably far forward considering there will be probably 600lbs around the nose. The current engine choice is a hefty 444lbs; JUST the engine. That is not including the firewall, mount, associated bracketry, pipping, etc. The engine mount structure will add the most of any other single item.

All avionics and fluid tanks will be forward of the pilot. The pilot will be situated near the trailing edge of the wing (again, much like warbirds). So with the big engine (bigger than one in a Mooney 201's I might add), all the fluids, and associated hardware at the leading edge and FORWARD with a heavy weight concentrated several feet forward of the leading edge, being tail heavy will not be the problem.

About the wing area being too small, the wing area is just about perfect for my wishes. I do not want yet another aerobatic aircraft. It wont be a bush plane either nor a 'business' plane. Again, its a poor man's warbird. Which reminds me, comparing the wing span to length it is still better than a Bf-109E! I remember reading several places that outsiders of Douglas were adamant that the A-4 was too small...wow did it prove them wrong! Cool

There are plenty of home-builts with bigger wing areas (proportionally) but they usually have odd airfoils optimized for speed (Midget Mustang comes to mind). I should add there that this thing is not optimized for fuel burn or "efficiency". It will be a warbird at heart optimized only for nostalgia and fun.

I have found wing span to length is a simple proportion that is a good 'rule of thumb' as long as the AR of your design is similar to the planes it is being compared to. Mine is comparative to most WW2 planes in AR, so I looked at a dozen ranging from the I-16 to Bf-109. The 109 having the lowest (hence its poorer turning abilities), the I-16 the highest (stellar maneuvering but horrible stability: to short).
I have verified this rule of thumb and its limits by studying real aircraft and looking at R/C airplanes as well. So far it works well...until the design becomes 'abnormal' like a pusher or delta wing.

THIS is what a 'too small and too far forward' wing looks like Wink

....

but dang its fast!
http://aircraftimages.net/display.php/Nemesis_4990

Every aircraft designer has their own tastes and with aircraft, there are an infinite number of ways for that to show through.

Top view
[img]

At any rate, I welcome the critiquing, it forces me to think over things again which is very important. I will and DO consider all serious thoughts (such as Jake's) and I hope more people offer some input. Im not expecting to win everyone over though, you can find fault in just about every design for one reason or another.

One thing I would really like some input on is the canopy styling. Seems pointless but it will point me in the direction of how I should shape the fuselage and consequently the rest of the aircraft. I HATE canopies that seem to bulge or stick out, the lines need to flow from nose to tail dang it!
Smooth
http://www.eaa.org/news/2012/2012-04-13_tecnam.asp
Smoother
http://www.eaa.org/news/2012/2012-04-19_aero-panthera.asp
curvy but smooth
http://www.eaa.org/news/2012/2012-04-05_diamonda52.asp
BULGE!
http://www.eaa.org/news/2012/2012-02-16_aerochia.asp

Personally I like this style for looks and because it is geometrically simple:
http://www.simmerspaintshop.com/forums/f29-aircraft-profile-painting/fw-190-a4-w...
Yep, that would be a Fw-190 Cool

Another plane with relatively small wings placed far forward.

The whole point of running through Roskam's method is that you get pretty solid numbers without geometry by basing the design off of similar aircraft. But if you would rather just hold your thumb up, then have it your way. Regardless of the weight of the engine, I still think your wing (if you maintain the wing area you show) will come out to being about a foot too far forward for the airplane to be reasonable to fly.

Just run a quick tail volume coefficient calculation, and compare what you get to the Swift. If you get the same numbers, then you are probably okay.

It would take you maybe a week of work to do 3 relatively easy calculations to take your airplane from a pipe dream to a possibility. Firstly, define your mission profile and run some quick performance numbers out of Roskam's (or Raymer's) books to get a few useful numbers such as wing loading, wing area, and fuel required. That'll tell you if your wing is big enough. Then, using the numbers from the Swift, find your tail areas so that you match the Swifts volume coefficients. Finally, do an x-plot to locate your wing.

Question me all you want, but I have the degree and I am a professional, so take that as you wish Wink

I'm not trying to be demeaning, if it comes off that way, I'm sorry. I just think you are doing a great thing by working this example, and you would be wise to do it properly.

AMD Athalon X6 1090T 3.2Ghz::EVGA nVidia GeForce GTX 560Ti 2GB GDDR5::8GB RAM
*The opinions expressed above are my own and are in no way representative of fact or opinion of any other person, corporation, or company.*

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Reply #8 - Aug 17^th, 2012 at 6:11am

wahubna Offline
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WMU Bronco
Michigan

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Posts: 1064

Jayhawk Jake wrote on Aug 16^th, 2012 at 9:04pm:

The whole point of running through Roskam's method is that you get pretty solid numbers without geometry by basing the design off of similar aircraft. But if you would rather just hold your thumb up, then have it your way. Regardless of the weight of the engine, I still think your wing (if you maintain the wing area you show) will come out to being about a foot too far forward for the airplane to be reasonable to fly.

Just run a quick tail volume coefficient calculation, and compare what you get to the Swift. If you get the same numbers, then you are probably okay.

It would take you maybe a week of work to do 3 relatively easy calculations to take your airplane from a pipe dream to a possibility. Firstly, define your mission profile and run some quick performance numbers out of Roskam's (or Raymer's) books to get a few useful numbers such as wing loading, wing area, and fuel required. That'll tell you if your wing is big enough. Then, using the numbers from the Swift, find your tail areas so that you match the Swifts volume coefficients. Finally, do an x-plot to locate your wing.

Question me all you want, but I have the degree and I am a professional, so take that as you wish Wink

I'm not trying to be demeaning, if it comes off that way, I'm sorry. I just think you are doing a great thing by working this example, and you would be wise to do it properly.

The dimensions did seem off to my eye, but I had just started. I tweaked the length a skosh, now it looks nice to my eye and some 6th grade math quickly proved it. No need for coefficients Wink

. KISS (Keep it Stupid Simple: Clarence 'Kelly' Johnson's engineering motto)
I will post some pictures later with the new proportions, they look much better with a shorter tail, the large wing-root chord did add a lot to the wing area though I should say, which is why I made it a taper wing.

Jake, I have to say you did come off that way and that you are only ~2yrs ahead of me..but that is more due to me being a transfer student from a CC (saved some $$ that way). I am currently one of only 3 in the engineering dept at WACO Classic, turns out we are THEE smallest GA manufacturer in the world! It forces me to be very hands-on in every dept though, so I love it.

Anyways, enough of that, I respect the community on here a lot and am grateful for it. That said, Jake, could you post some screen shots of your design?

« Last Edit: Aug 17^th, 2012 at 2:00pm by wahubna »

‎"At that time [1909] the chief engineer was almost always the chief test pilot as well. That had the fortunate result of eliminating poor engineering early in aviation."- Igor Sikorsky

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Reply #9 - Aug 17^th, 2012 at 9:26pm

Jayhawk Jake Offline
Colonel
Wichita, KS

Gender:
Posts: 483

wahubna wrote on Aug 17^th, 2012 at 6:11am:

Jayhawk Jake wrote on Aug 16^th, 2012 at 9:04pm:

The whole point of running through Roskam's method is that you get pretty solid numbers without geometry by basing the design off of similar aircraft. But if you would rather just hold your thumb up, then have it your way. Regardless of the weight of the engine, I still think your wing (if you maintain the wing area you show) will come out to being about a foot too far forward for the airplane to be reasonable to fly.

Just run a quick tail volume coefficient calculation, and compare what you get to the Swift. If you get the same numbers, then you are probably okay.

It would take you maybe a week of work to do 3 relatively easy calculations to take your airplane from a pipe dream to a possibility. Firstly, define your mission profile and run some quick performance numbers out of Roskam's (or Raymer's) books to get a few useful numbers such as wing loading, wing area, and fuel required. That'll tell you if your wing is big enough. Then, using the numbers from the Swift, find your tail areas so that you match the Swifts volume coefficients. Finally, do an x-plot to locate your wing.

Question me all you want, but I have the degree and I am a professional, so take that as you wish Wink

I'm not trying to be demeaning, if it comes off that way, I'm sorry. I just think you are doing a great thing by working this example, and you would be wise to do it properly.

The dimensions did seem off to my eye, but I had just started. I tweaked the length a skosh, now it looks nice to my eye and some 6th grade math quickly proved it. No need for coefficients Wink

. KISS (Keep it Stupid Simple: Clarence 'Kelly' Johnson's engineering motto)
I will post some pictures later with the new proportions, they look much better with a shorter tail, the large wing-root chord did add a lot to the wing area though I should say, which is why I made it a taper wing.

Jake, I have to say you did come off that way and that you are only ~2yrs ahead of me..but that is more due to me being a transfer student from a CC (saved some $$ that way). I am currently one of only 3 in the engineering dept at WACO Classic, turns out we are THEE smallest GA manufacturer in the world! It forces me to be very hands-on in every dept though, so I love it.

Anyways, enough of that, I respect the community on here a lot and am grateful for it. That said, Jake, could you post some screen shots of your design?

I may only be 2 years ahead of you, but I do have experience to know how to design a plane, including professional experience.

Just look up tail volume coefficients, it's the easiest calculation there is and will save you so much effort later. Figure out how much fuel you need, then do some quick algebra to figure out how big your wing needs to be, then from there you can figure out how big your tails need to be. Done. Minimal effort, and you will be so much closer to a working aircraft than before.

I'll dig up my design sometime next week.

AMD Athalon X6 1090T 3.2Ghz::EVGA nVidia GeForce GTX 560Ti 2GB GDDR5::8GB RAM
*The opinions expressed above are my own and are in no way representative of fact or opinion of any other person, corporation, or company.*

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