An Aircoupe...But not really.

 Hi, Steve.  Sounds like a neat project idea.

However, I think you're going to have a tough time with the FAA to get this licensed as Experimental Amateur-Built.  After some rather public examples of production-type aircraft that were allowed to be re-licensed as homebuilts, the FAA has really clamped down on the process.  A guy I know with a Cessna 172 that he wanted to install a Chevy engine on talked to the FAA.  He offered to build new wings from scratch (like you're looking at) but the FAA said that wouldn't be enough...they wanted him to scratch-build the fuselage.

Best (positive) example I can think of is the Blanton Javelin V6 STOL, aka the "Defunky Cub".  The design takes a Piper Tripacer, stretches the fuselage and the wings, and installs a Ford V-6 engine.  This is a traditional homebuilt that the FAA has licensed several examples of.  But there's more work done on that Tripacer airframe than just strengthening. 

As far as where to start, obviously, the first thing to do is work with the FAA in advance to ensure you could get approval.  It would be possible to license the plane in one of the OTHER Experimental sub-categories (such as Experimental Research and Development), but the restrictions are quite a bit tighter.

One thought might be to scratch-build the fuselage.  I'm not that familiar with the design, but it seems to me that it's probably not any more complex than an RV.   If you're planning structural upgrades, you'd be better off doing them from scratch rather than try to add them in later.  You could start with a decrepit Ercoupe, and cut new aluminum sheet to match and re-using the welded and metal bits.

Thanks! And yeah...I think I could probably scratch build the fuselage. Now obviously this is gonna be alot of design work...how should I go about designing it?

John,

I am an Ercoupe owner and pilot.  Do you plan to use the plane for your missionary work?  It is a bit small for that from the descriptions a friend from Andrews University, who regularly flies missions in Bolivia, has laid out for me .  If it is for personal use, you have a great airplane in your sights.

I understand your desire to restore one.  If you could get an airworthy plane for $20,000, expect to put at least $10,000 more into it with the modifications you would like.  With the big NACA airfoil on the plane, I do not believe you will get much more speed out of it even with your planned engine switch and perhaps a prop optimized for the speed you seek.

If you have already found the actual Ercoupe you want, my suggestion would be to an 0-200 crank in the engine (not sure what the plane will have, and that should bring you to 100 hp).  Make sure the center section of the airplane is sound by having the rivets ultrasonically inspected. There is a Service Bulletin out for how to do this...  Make sure all the AD's are taken care of and depending upon the prop pitch, have it modified for cruise or replace it if it cannot be modified.

I would leave the metal wings alone or find a C, D or E model without rudder pedals that still has the original fabric wings.

There is a great type club for the airplane, the Ercoupe Owners Club and a separate Yahoo Group dedicated to technical aspects of the Ercoupe.  There you will find very knowledgable people who will gladly advise you on taking an orginal Ercoupe and making it a great classic without trying to convert it to an Experimental or Exhibition airplane.  Plan to invest some money to do some of these things.  This too can cost you upwards of $10,000 above the base price of the plane you find.

Best,

John

John,

A couple of resources you can start with are Dan Raymer's primer on homebuilding, Simplified Aircraft Design for Homebuilders (www.aircraftdesign.com). The author covers the basic theory behind aircraft design and how to get started.  This is not a book about engines, fabrication, materials or technique.  It is not inexpensive at $50, but perhaps you can find a library copy or a used copy.  A good source for used books is: www.abebooks.com

The other resource is DaVinci Technologies, Airplane PDQ for about $99 (www.davinci.aero).  The software has a base package and several add-ons.  This software allows you to design your own airplanes from scratch.  There is a demonstration video on their website. They once marketed a limited use shareware version that expired after a certain amount of time as a try before you buy promotion. They still might.  A nice thing about this program is the ability to save your design as a fully flyable airplane (maybe) in the flight simulator X-Plane.  You can actually check out the performance as it relates to your ideas or those you incorporate from an airplane like the Ercoupe.

One other note, Dr. Raymer has a number of published works that are meant for college and graduate level engineering students.  Stick with the title I mention above for now...

 I admire your enthusiasm for this project.  Just be sure to keep an open mind.  That will allow you to see all the possibilities and to minimize possible frustration if a door closes.

Best,

John

John, you garnered some helpful replies that tried to answer your question, "So where should I start?"  My reply is tell you your idea and question are wrong and to throw cold water on the whole business.

As one replier mentioned, you'll have considerable difficulty getting the FAA to accept this project as an experimental...and that's just the paperwork portion of the project. The actual work is very complex and has not been done before so you have nothing to guide you. For instance, you want to put in a higher-powered engine and mention strengthening the airframe...but your biggest problem at higher speeds may be flutter, which isn't a matter of simple "strength".  At 17 years old, are you prepared or do you know who can do proper flutter analysis?

On top of this project--which would be a major undertaking for an accomplished experimenter--you want to join MAF as a skilled pilot and A&P.  Dreams are great, but you gotta start being realistic.

Your best bet might be to buy a partly done RV or similar experimental project you can finish. Work on it while you get your A&P and your pilot training. When you finish it you can sell it for at least your direct costs (maybe not your labor time). The modified Alon would be very difficult to find a buyer I think.

Sounds like fun, however....     If you want rag wings, forget the Alon.   The wings dont take well to fabric.  The biggest problem when finding a "project coupe" occur in a couple of areas.  First, the center section spars must be inspected very well and ultrasounds done of the rivets.  The main carry through spars are subject to severe inter-granular corrosion.  The wing spars are subject to the same thing.  

As for mission work, it isnt very practical.  The useful load with full fuel and a pilot isnt very much.  It is a terrible short field aircraft.  Approach speeds and landing speeds are high for very good STOL performance. (arround 80 mph). 

They are a ton of fun to fly.

Again, DO NOT BUY ANY ERCOUPE THAT YOU HAVE NOT HAD A PREBUY INSPECTION BY SOMEONE VERY FAMILIAR WITH COUPES.  A local A&P or AI would be good if they are familiar with coupes throughly.

Hi John,

I own a 1950 Mdl G Ercoupe.  I've taken it apart to do a complete overhaul on it, and have considered doing some of the same thing as you propose, but can't seem to get started due to my work and family schedule.  I flew it for about 60 hrs before storing it 4 yrs ago.  It has a C-85, rag wings, and no rudder pedals.  This is not a bush plane, but gets in/out of an 1,800 ft grass field at gross with ease using a climb prop.  I can sell the airplane very reasonably w or w/o engine.    I have to agree with all the other advices -- make sure you can meet the 51% rule before you start -- see Advisory Circular 20-27G, of 9/30/2009.  

Thanks everyone for your replies! Sorry it's taken so long for me to get back.

Just a clarification, I'm not going to be using the Aircoupe for mission work, it's going to be my personal airplane.

Now to answer a few of your comments...Most of what I'm doing to this airplane has been done before (There have been two or three ercoupes built with retractible gear, ercoupes originally came with fabric wings, and the aircoupe was built with the C-90, which is the same engine block as the O-200 (and some people put the O-200 on it), and the corvair conversion is a perfect engine to put on anything that's flown with an O-200.) And also just to say, I understand this is a huge undertaking and the project as a whole has never been done before. But that's sort of the perpose of the EXPERIMENTAL Aircraft Association isn't it? To help people do with airplanes what has never been done before. I know I don't have many (if any) of the skills or knowledge I will need to complete this project...but then again almost every single really NEW aircraft (I'm talking ones back in the early 1900's) was designed by people who didn't know what they were doing. I'm in a lot better boat than they were. I can learn everything I need to know, because the main ideas have all been done before. I don't want to spend thousands of dollars and man-hours on a plane that I'm just going to sell before I build the one I really want. So yeah. Thank you all for the help!

P.S. Please don't take offense at that...I do understand y'all probably have much more knowledge than me, and have a much better idea of what I'll be getting myself into than I do....but would any airplanes ever been designed and built by homebuilders if they really knew what they were getting into at first?

Again, you must not put Ercoupe wings on an Alon.  Yes they look the same and yes they can be put on. DO NOT DO IT!

Ercoupes are a nice plane.  There is an awful lot of incorrect information and dangerous information put out by some Ercoupe owners that think they know what they are doing/talking about.  The airport I keep my airplanes at happens to have on field one the the 3 best Coupe experts in the country. PM me and Ill give you his name and phone number.  You can call him or I can get Big John's phone number for you.  If you buy a Coupe, you will soon learn who Big John is.  He is the go to guy on Coupes.

Ive seen some absolutely stupid things done to Coupes. Things that are down right dangerous.  All done by folks that will tell you its cool to do.  Thing that will kill you.  If seen center section spars cut, ground, drilled etc to put in seat mods. If seen spars cut and not replace when putting in the wing inspection plates.  There are "experts" that will say its ok.  It aint.  Ive even seen a coupe with one Coupe wing and one Alon wing on it. They are built different.

Why a corvair?  If you fly off some place and have an engine problem.  Its down time waiting on parts.  With a c85 or 0200, you can get them fixed almost anywhere. Many shops at local airports wont touch a Corvair.  Which leaves you as the mechanic, which is fine if you have or can borrow tools out on the road. You can do all the mods your considering if you so desire, however, the airplane wont perform much better if any better than a standard coupe. Remember an Alon is heavier than a C or D coupe.

Matter of fact, ill send you a PM with Mark's phone number.  Call him and discuss your ideas. He will be more that glad to talk/help you anyway he can.  Thats the best part of owning a Coupe.  Every owner will bend over backwards to help you.