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Back To The Future: The Quest For The Grand Slam Homebuilt

The EOS/001 experimental aircraft design at Oshkosh 1973 with the C-5A

 There's a pretty good chance you have no idea what this little experimental airplane is that's sitting on runway 18/36 at Oshkosh '73 under the wing of the huge Lockheed C-5A Galaxy.  This was just 2 years after the BD-5 had electrified Oshkosh, and this little single-seat airplane had come along to offer up some competition in the 2-stroke powered super-cool looking and cheap-to-build arena.  

 More on the airplane in a moment, but first it's interesting that this picture was taken right out on the runway.  If I remember correctly, there was no place to put the C-5A as this was long before AeroShell Square existed, so they left it on the runway, which was pretty cool because we were allowed out there in the evening to look things over.  For some reason, the little all white EOS/001 prototype had been positioned out there as well.  I was only 12 at the time, but I was very knowledgeable about what was going on in the homebuilt world, and we had a BD-5 kit sitting in the living room at home, so I was paying real close attention to what this EOS airplane was all about.

 I should probably clarify that the outer wing panels aren't installed on the airplane in this pic.  I'm not sure why they weren't on it, but I'm pretty sure they had been on it during the week sometime, but maybe they weren't.  I checked the Oshkosh365 online back issue archive of Sport Aviation earlier today (a fab perk of being an EAA member) and found a few articles on the EOS/001 from late 1972 and 1973.  From what I found, the airplane still hadn't flown when it was at Oshkosh in 73.  In fact, I can't find any record that the airplane ever did fly.  It's a bit of a mystery, and I'm hoping someone has some info on whatever happened to this great looking little airplane.  If you do, please let me know!

The sleek and simple EOS/001 homebuilt from the early 70's

 Here's the real point of all this: we need a 'grand slam' single-seat homebuilt airplane to emerge into the marketplace.  An airplane that can satisfy 4 major desires:

 1) affordable

 2) great performance but not excessively demanding to fly

 3) relatively and realistically easy to build

 4) electrifying looks

 These were the 4 big promises of the BD-5, tho I believe it was coloring outside the lines on some of the claims.  Then it left thousands of builders stranded without complete kits as the 70's progressed.  The EOS/001 actually looked like it was possibly better suited to fulfill those desires, but it disappeared pretty much without a trace.  The RV-3 had hit the scene around this time, and while it's a fantastic airplane, it's really more work and expense than what I think the mass market is looking for.  Then the Ultralight movement came along in the late 70's with the idea of inexpensive flying, but none of those airplane could ever offer the same kind of experience as a BD-5 or EOS.  There have been some other designs along the way over the years, but the definitive single-seat, affordable and easy to build 'electrifying' airplane still doesn't seem to exist.  Maybe I'm missing a great design... if so, please let me know.

 I am excited however at what Sonex has been working on to address much of what I'm talking about.  They are currently building the prototype Onex aircraft, a single-seat derivative of the popular Sonex airplanes.  I really like what the Sonex airplanes have to offer, but I know a lot of people wouldn't say they look 'electrifying'.  Regardless, the Onex definitely looks very interesting.  Hopefully we'll see what it really has to offer at Oshkosh 2010.  And you can be sure I'll be posting lots more about it soon.

 Ultimately I'm trying to stir up thought and discussion.  I even have my own design for an electrifying airplane that has recently fallen out of my head and onto paper, or at least onto the computer screen.  I've seen a lot of cool airplanes over the years, and I gotta say that what I've come up with is right at the top of the pile.  It's so good in fact that I'm not gonna share any details right now.  I'm trying to find other people who have real vision for filling this need in the experimental aircraft world, and then we'll see what comes next.

 Mostly I'm looking for people to talk back... please, say something : )


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Reader Comments (26)

I like your thoughts on this. I look back at a these failed designs (BD-5, EOS) and wish there was something similar today. There were a few successes that came out of the ARV movement worthy of mention though:
- Avid - not high speed, but the original A model was lightweight and gave great performance - kit price is high, but the Mohawk is a similar version from plans

-Starlite - Mark Brown did it right. He built a simple, light plane and proved it could fly before selling anything. Only drawback: kit only.

The thing I hate about these is they all grew over time so that now a Kitfox has larger engines and the Pulsar too - and current kits are pricey.

I think an alternative would be to bring back something like an updated KR-1 (or b model motorglider). I personally would like to see an original concept BD-5 - lightweight from composites, small engine - it might actually work.

June 2, 2010 | Unregistered CommenterBill

Bill- The Starlite is a great example and one that I had forgotten about. In addition to the kit-only aspect, I'd also have to say that it didn't look 'electrifying'... not that it didn't look good, it did, but even tho the Starlite and the EOS actually are pretty similar in overall key design points, the EOS looked hot (in my opinion).

I understand why so many designs either start at two-place, or wind up there, but I think there's something vitally important to the single-seat airplane. The smaller airframe and lower power requirements really help to reduce both the initial costs and the ongoing expenses. Plus, when someone moves up to a two-place aircraft, their single-seat is likely to be on the market at a great price, opening the door for another person to enter the sport relatively easily.

I also feel that the best solution to the cost issues are both designing an airplane to specifically take advantage of less expensive materials, AND making the airplane available in a form that falls between 'plans only' and 'kit'. I guess we'd call it 'sub-kit', where only some of the difficult parts are made available, but the builder is responsible for finding and acquiring much of the materials needed for the airplane along with fabricating all of the simpler parts.

Thanx for the great comment : )

June 2, 2010 | Unregistered CommenterMartt (admin)

Hi Mart,

I agree with your comments regarding Sonex/Onex. The design does not quite meet your criteria #4: electrifying looks. But, it meets criteria 1-3 so well, who cares about looks? I say forget about looks, what the Sonex people have accomplished is amazing. Considering a Part 103 legal ultralight trike with Rotax 447 is 17 grand, pushing 20 with a few options; a Onex at perhaps just a bit north of 20 grand would be an incredible bargain.

I'm not a homebuilder (yet!) but I have a feeling great looks and easy/cheap to build are mutually incompatible design characteristics. If so, I'd sacrifice looks every time.

BTW, I hope you're still working on Project VP!

June 2, 2010 | Unregistered CommenterJeff

what about the Hummel aircraft? Nothing cool about 1/2 of a VW engine, but the airframes look fast & sporty.

June 11, 2010 | Unregistered CommenterDave K

Well I've got good news for you guys!
I am "working" on my own design as well, but it will be hard to top this one:

September 14, 2010 | Unregistered CommenterTom

Tom- Very impressive looking machine! I'll be in contact with you soon... I would like to do a story on your beautiful airplane!

September 14, 2010 | Unregistered CommenterMartt (admin)

This aircraft is for sale on eBay!

July 16, 2011 | Unregistered CommenterW Parker

W Parker- Wow, that's pretty incredible that the EOS aircraft is surfacing after all these years for sale on eBay! I'll do a post about it soon. Nice find, and thanx for sharing : )

July 16, 2011 | Unregistered CommenterMartt (admin)

Yeah, I was surprised when I saw it there too!

July 16, 2011 | Unregistered CommenterW Parker

FWIW, Wikipedia says the protoype was the only Eos ever built, and that it crashed on first flight due to engine seizure and was rebuilt and repowered with a VW. So is the one on eBay the one and same??

July 22, 2011 | Unregistered CommenterDJField

My recollection from way back in the day was that only the prototype was built, built some research the other day made me think a couple kits might have actually been built. I'm guessing the one on eBay is not the prototype (but I really don't know for sure)

July 22, 2011 | Unregistered CommenterMartt (admin)

The wikipedia article links to a web archive of the August 1978 Flight International, which says that the Eos has flown some 16 test flights to date. It seems unlikely that the prototype would be stored in a shed with no log books or any records of any kind, but it's not impossible. And it could be just coincidence that the seller thinks it has some 16 hours on it.

July 22, 2011 | Unregistered CommenterDJField

The only remaining airframe NOS/002 is currently for sale . Listed on Craigslist in Springfield, MO.

November 13, 2012 | Unregistered Commenterconundrum

There are a few eos planes unfinished I know of 2 in michigan. One of them which I am currently working out a deal with the owner.

September 22, 2014 | Unregistered CommenterClint

I have an eos! Hanging in my garage! Not complete yet, but working on it

February 1, 2015 | Unregistered CommenterClint

There are at least 3 EOS/SFA planes out there. Its is possible more may exist. I spoke with a man from California who sold 10 sets of plans in the early 80's. The prototype is in San Diego CA. One is in PA, and mine is in Michigan. The prototype is in bad shape. however the one in PA has been restored and should fly this summer. My EOS/SFA is short instruments and a few hundred more hours and will be ready to fly!

May 28, 2015 | Unregistered Commenterclint


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How about the Lightning Bug? Designed by the late Nick Jones. 200 + MPH on 100 hp Rotax. Single seat. Very sleek. Any interest?

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