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where to turn for design help

Posted By:
Milton Stephenson
Homebuilder or Craftsman
#1 Posted: 11/12/2009 16:11:34

I am very interested in designing and building my own airplane.  The only problem is that I'm not an aeronautical engineer.  However, I feel that I have the drive necessary to pursue this dream with all the passion, and money, I can muster.  While I think I can come up with a basic design, such as how the airplane is supposed to look, I am worried about the much more important details as to how to come up with an airfoil design that will match the kind of flying that I want to do.

Here are some design parameters:

2 seat tandem low-wing with full controls in the back seat.  All composite construction.  Elliptical wing shape for that classic WWII look.

capable of gentleman aerobatics (I like to be upside down and do spins, but have no desire to really wring it out)

225 KTAS cruise at 75% power

1000-1500 NM range

retractable landing gear, and T-34 style canopy

Ceiling FL250

I'm not sure about the engine but I'm guessing an IO-540 at the minimum...probably turbocharged.


Any help would be greatly appreciated.


David Darnell
#2 Posted: 11/12/2009 21:10:29

  Well, Its not "everything" you specified (IMO, no homebuilt ever is) but you might start by looking at a established design, and use it as a "starting point". In your case, a Brokaw Bullet.

Jeffrey Meyer
Homebuilder or Craftsman
#3 Posted: 11/13/2009 11:01:14

Hi Milt

I highly recommend a great "cookbook" for people like you (and me) who want to design and build their own homebuilt aircraft:

"Simplified Aircraft Design For Homebuilders" by Dr. Daniel P. Raymer, ISBN 978-0-9722397-0-7

I call it a "cookbook" because it really does the job of explaining the essentials of DIY aircraft design in simple, layman's terms without complicated formulae.

I think that Dr. Raymer is also a member of the EAA.

Frank Gaggia
Young Eagles Pilot or VolunteerHomebuilder or Craftsman
#4 Posted: 11/13/2009 19:31:25

Hi, Milt,

I'm not an aero engineer, either, although I worked in the design department of several large aerospace companies during my 30+ year engineering career.  I have an extensive design library (including Dr. Raymer's books) as I like to think about my own designs at times, too.  It can be, and has been, done, but is quite an undertaking.  I'm having enough trouble just building my kit.

If you'd like to see a couple of designs that I think would come close to your criteria, check out Jeff Ackland's RADIAL ROCKET or LEGEND.  Cool designs if you can afford that type of machine (I can't!).

Frank Gaggia, Jr.

EAA 11549

Ross Carbiener
Homebuilder or Craftsman
#5 Posted: 11/18/2009 20:49:10

Milt,  I suggest becoming a "student" of previous designs.  Look at what others have done.  For instance, a person designing a steel tube fuselage would look and see that most designs that use a 4 cylinder engine have 3/4" .035 for the longerons, etc.  So, I recommend looking around.  The Emerude uses the elliptical wing you want, the Beryl is tandem (and elliptical).  For moldless composite see Rutan designs.  In this way you can design using other peoples engineering and your good judgement.



Ried Jacobsen
#6 Posted: 12/30/2009 21:47:21

In the early 1990's John Roncz had 10 or 12 articles in Sport Aviation covering aircraft design.

In the early 2000's Neal Willford had a similar series of articles.

Go to the EAA Members Only section of this website and search Sport Aviation articles by author for a list of downloadable articles to review.

Also, look at similar designs like others have suggested, it can give you a bit of a head start on configuration issues.

Chase Balcom
Homebuilder or Craftsman
#7 Posted: 1/1/2010 22:21:36

  Hi ,..I am building my own design ..and with a nostalgic look,..it is a high wing tail dragger,..3 place STOL ..I'm not looking for the same speeds you are which makes my venture a little easier,..I should have a 130 mph cruise when I'm done on 140 hp,.. and an airframe that will carry twice it's weight,..

    I am an engineer but not aeronautical as degree's go,.. but from my own experiences ,..this being my 15th build,..

I've learned that the only stop sign's that pop up are the ones that you  plant yourself,.. if you haven't quite got that warm and fuzzy feeling about any concept of the design ..build a model ,..scaled down, in every aspect including  HP to the "T",..if it's not in your forte,.. find someone who is into building new concept models of your design,.. it's the safest ..cheapest approach without investing years of time and efforts into a project that doesn't meet your goal,..choose an existing airfoil since your looking for higher speeds,..it will save you allot of testing to find it's" no go envelope"

    The new group that took over the kitfox lite is building their wings all composite,..so are the cubs now,.. I have only worked on one composite design of a bi plane prototype ,..and it is tedious building from the outside in,..one mis thought stage ..and  your back to square one,..my preference is  6061 and 4130,..but that is only because I have too much old school back ground to get all warm about composites,..

   one thing to consider with composites ..and the fact that they are lighter ..at the speeds your considering ,..lighter is not always good,..just for giggles take notes of the weights of aircraft that are existing that can travel the speeds your looking at  that are close to your design,..you might end up with a really short wing to get the equivelant performance.

just my 2.5 cents worth



Hank Avent
#8 Posted: 4/23/2010 12:01:03


I've recently completed a VANS RV-7. Building this all metal, riveted airplane, has whetted my appetite and I'm raring to build the nostalgic aircraft I dreamed of flying in my younger cowboy days. The problem I'm running into is engineering the airframe. I started out hiring a professional engineering outfit who did the basic airframe layout. But I can't afford this sort of engineering cost and still be able to afford the materials for the airplane. The EAA folks told me to check this forum and I came across your posting. So I'm emailing you to see if you might be willing to help me with engineering the definitive structural components. I'm happy to pay you for your assistance. 

I began using Tom Rhode's book, Stress Without Tears, but I'm not sure about the formulas and where my calculations are leading me. I need someone to confirm that I'm using the right formulas in the right way. 


Hank Avent

EAA #760686