Open Source Kit Aircraft

Homebuilt Aircraft & Kit Plane Forum

Help Support Homebuilt Aircraft & Kit Plane Forum:

Noah

Member
Joined
Nov 19, 2010
Messages
23
Location
California
Does an open source kit aircraft exist?
Some of these designs have been around long enough there are volumes of modifications and resources, so would an open source aircraft make sense?

I'm thinking something like a Long EZ, but even more simplistic.
This aircraft might be built from wood and plastic and theoretically be:
15% heavier
50% cheaper
75% easier to build

Plans could be as simple as Solid Works drawings for vacuum forming bodywork and templates for plywood. We need an open source flat pack aircraft.
 

autoreply

Well-Known Member
Joined
Jul 7, 2009
Messages
10,775
Location
Rotterdam, Netherlands
People are willing to trade off quality/performance for lower cost. At least, they do in cheaper products. They don't in higher quality products that are expensive anyway and airplanes are the prime example.

Simple is good, but there's a basic limit in that. I think the Hummelbird, Long-Ez and other came quite close.
 

toyohabu

Member
Joined
Jul 21, 2010
Messages
13
Location
Huntsville, AL
What would the advantage be? Most plans cost under 1000 some considerably less. Who would volunteer to build the prototype in order to validate the design? What would the purpose be to a open source?
 

Inverted Vantage

Formerly Unknown Target
Joined
Jun 19, 2008
Messages
1,116
The guy died during a test flight for that aircraft - no fault of the design though, it was due to some stupid Australian law at the time regarding spin testing altitudes.

An open source aircraft would be an interesting endeavor, however I feel that the actual design would end up having too many cooks in the kitchen, so to speak.
 

Dana

Super Moderator
Staff member
Joined
Apr 3, 2007
Messages
10,324
Location
CT, USA
With open source software, anybody can download the code, compile it, run it, and repeat with the new version as soon as it comes out. Aircraft simply arn't that way, when it takes most people years to build and few build a newer version of the same plane.

That said, the Long EZ is perhaps as close to open source as you can get... abandoned by the original designer, but with plans floating around and an active community of builders making various mods and improvements.

I doubt a wood version of the Long EZ would be simpler, though... the hotwire foam and glass construction is about as simple as you can get.

-Dana

"If you're not a liberal at 20, you have no heart.
If you are not a conservative when you're 30, you have no head."
-- Winston Churchill
 

Noah

Member
Joined
Nov 19, 2010
Messages
23
Location
California
The BD 5 was popular because it cost 5k. People would rather buy a 20mpg car that costs 20k than a 80mpg car that costs 80k. Locosts are significantly more successful than Caterhams.

An open sourced aircraft would offer unparalleled support and innovation. Cost would go down significantly with the aftermarket. There would be an infinitely expandable knowledge base.

I was planning to build a rv4, velocity, or similar before this, but I'm willing to sacrifice 10k in cost for 15% in weight. Fuel burn would increase slightly, but performance loss would be negligible. I wouldn't have a problem building and testing it.

I searched and it seems like there is lots of interest, but little in the way of movement. The next step should be design requirement proposals. I'd like to see a small ply/plastic tandem faceted delta wing that meets LSA requirements. Elevons are simple but a cannard or tail would allow flaps and thus stol.
 

Noah

Member
Joined
Nov 19, 2010
Messages
23
Location
California
With open source software, anybody can download the code, compile it, run it, and repeat with the new version as soon as it comes out. Aircraft simply arn't that way, when it takes most people years to build and few build a newer version of the same plane.

That said, the Long EZ is perhaps as close to open source as you can get... abandoned by the original designer, but with plans floating around and an active community of builders making various mods and improvements.

I doubt a wood version of the Long EZ would be simpler, though... the hotwire foam and glass construction is about as simple as you can get.
The long EZ is still a 1-2k hour build. Most of that is in fiberglass, paint and prep. I'd like to see it take only 200 hours to build the plane with no painting and half the parts count.
 

Dana

Super Moderator
Staff member
Joined
Apr 3, 2007
Messages
10,324
Location
CT, USA
I'm not extremely familiar with the EZ, but its composite construction already is a low parts count, no? Any alternate built up structure would doubtless raise the parts count.

If you went molded parts, etc., you're talking expensive tooling, hardly the direction you want for "open source". If you're talking vacuum formed skins, you're talking real expensive tooling for the sizes involved (I worked in that business for awhile).

-Dana

"Never interrupt someone doing something you said couldn't be done"
-Amelia Earhart
 

flyoz

Well-Known Member
Joined
Jul 30, 2008
Messages
149
Location
Near Sydney
Long eze and Varieze family have been discussed before
The Varieze is about the closest and simplest
Costs of milling has come down considerably and all the wing and fuselage parts could easily be milled . Some final shaping would be required but it would be minimal and sanding shapes could be supplied . Many large boat hulls and decks are now made this way ( 40 ft milling machines are available ) Computer hot wire cutting does not allow for the detail ( ie recesses )or work on PVC foams ( fuselage) so i would discount that method although it will help considerably time wise and is now avaiable
Milling would reduce the foam parts to a basic cardbord box , save hundreds of hours and ensure accuracy and less mistakes
Ultimately small individuals will make certain parts and the builder will have to source plans and do the rest
Rutans designs are in fact the closest thing to true open source ( Thanks Burt !)
You can buy from a variety of sources , canopy, landing gear , engine mounts and most of the control systems plus you get a known product with the benefit of years of feedback ( published CP newsletters )
Flyoz
 

craig saxon

Well-Known Member
Joined
Sep 26, 2010
Messages
549
Location
Canberra, ACT, Australia
The guy died during a test flight for that aircraft - no fault of the design though, it was due to some stupid Australian law at the time regarding spin testing altitudes.

Not quite true...

The Ligeti Stratos, a strikingly beautiful joined-wing microlight which cruises at 112 kts on 1.3 gph was originally designed and flown 20 years ago in Australia by Charles Ligeti. His tragic death while test flying a modified design, aerodynamically different than the original, brought the project to a halt in 1987. The aircraft remained widely admired and Internet discussions and citations continued for over twenty years.
 

Hot Wings

Grumpy Cynic
Log Member
Joined
Nov 14, 2009
Messages
8,140
Location
Rocky Mountains
What would the advantage be?
The biggest advantage, IMHO, of an open source airplane is that the builder doesn't get stuck with a half finished orphan when the company he purchased a partial kit from goes bankrupt.

Here in the US another possible advantage comes with regard to liability. Making a part for someone based on the specifications they supply tends to get treated differently than when the part supplied is made by the person setting the specifications.
 

Noah

Member
Joined
Nov 19, 2010
Messages
23
Location
California
500ft spin test? Sounds unlikely but so do a lot of aircraft crashes...

Foam plugs aren't too expensive. Plastics require no paint prep or epoxy like composites.

[...] edit: Hot Wings said it better than I could.

I made a couple quick concepts in solidworks... here goes my LSA 1+1. Its made from four sheets of polycarbonate.

This one is a 1+1 configuration that is W4xL14ft with wings folded and elevons (attached to winglets and would slide along the wing). W10xL16ft with both out.
Its a tricycle pusher much like the long EZ but with triple plane plywood wings that provide trim, and full length 3/8" polycarbonate canopy bodywork which means build time is minimal and speed is maximized. Over 100sq ft of lifting area with a low CG makes STOL easy. Optional wingtip floats could carry extra fuel.

Also it could have either a 6.5ft track and fixed gear or 4ft track retractable gear. It could be road legal with leaning how the carver is and would only require ~50lbs in 3 motorcycle coilovers, stronger gear motors, misc electronics, and a front brake: http://theeestory.com/avatars/Fly_the_Carver_One_.jpg?1251761252

Lastly, a 300hp turbocharged, dry sump, motorcycle engine might include hinges that point the prop and engine 90* down with small ducts to the wings and nose for VTOL, roll, & pitch respectively. ;)

Heavy inspiration from spaceshiptwo, Delorean, and the Long EZ.
What am I forgetting that will make this fall out of the sky? I'm worried the CG is way close to my lift center.
 

Attachments

Last edited:

Inverted Vantage

Formerly Unknown Target
Joined
Jun 19, 2008
Messages
1,116
Neat idea, love the seating arrangement, but...where are your batteries? That also looks like you've got the fan stuck inside the fuselage. You're starting out pretty much like I did (I'm also 21 now, but I started doing this awhile ago).

I like where you're going with the idea though. Try out some of Dan Raymer's books, especially his "simplified aircraft design for the homebuilder". I also have a spreadsheet that I think may help you, though it's not been tested with an ACTUAL aircraft. PM me for details.
 

Noah

Member
Joined
Nov 19, 2010
Messages
23
Location
California
One more pic with the right wing folded up. Seating is close; almost like a motorcycle.

Batteries/fuel behind the small of passenger's back. The firewall will angle forward there with the seat because of the slightly reclined position so explosives on the correct side of the firewall. Controls could be at the side and forward "step out" exit would be possible when the front wheel is down. ...step on the dash left or right of the front tire, step on the ground.

I'm starting to doubt the folding wings. Maybe gull wings instead. 120sq ft wing area (16x10) vs 96sq ft (16x6.5) The 20%sq foot difference means heavy hinges, motors, and support structure. Maybe 150lbs or 12.5% with the extra wing.
 

Attachments

Topaz

Super Moderator
Staff member
Log Member
Joined
Jul 29, 2005
Messages
14,768
Location
Orange County, California
How is it that everyone seems to have Solidworks? Last time I checked, that's a multi-thousand dollar piece of software.
 

greywuuf

Active Member
Joined
Nov 4, 2010
Messages
36
Location
Alaska
How is it that everyone seems to have Solidworks? Last time I checked, that's a multi-thousand dollar piece of software.
No kidding, think of the numbers of proven plans you could buy with that !

Seriously I have burned my "free trial" time with auto desk a number of times and have to resort to friends in the industry to get my full size patterns for Kayaks and foam formers and the like Drafted out into print files :cry:
 

Hot Wings

Grumpy Cynic
Log Member
Joined
Nov 14, 2009
Messages
8,140
Location
Rocky Mountains
How is it that everyone seems to have Solidworks? Last time I checked, that's a multi-thousand dollar piece of software.

You can also get a limited time Student version for not very much. I've not been able to determine of it is a one time thing or if you can purchase student copy each year you are student. If so, $140 a year is a pretty cheap "license fee" for what it will do.

But, if you "need" the software it's worth every penny. If you factor in how much more productive it can make you and what it would cost to have the same work done for you the savings start to add up. But that first lump sum cash outlay does make entry a barrier to us independent operations.

For my current project I'd either have to make my casting patterns by hand at the desired ratio to account for shrinkage (a rather time consuming task) and end up with less than ideal castings. Or I do them in actual size (still a bunch of time) and have them scanned and cleaned up and resized in CAD so I can have high quality patterns CNC cut.

The one project I'm teaching myself Solidworks for, will probably save me about a 1/2 the cost of a new copy of SW compared to subletting the work. And the "little things", like it telling me in less than 30 seconds how much aluminum the casting will take, how much it will weigh and exactly where the CG of the finished part will be, is just an added bonus.

Expensive? Yes. Worth it? For me, Yes.

Note: I don't work for SW, or profit from the sales of SW in any way. :gig:
 

Noah

Member
Joined
Nov 19, 2010
Messages
23
Location
California
Solid works was free for me. I just called and said I'm a student using it for design and they sent me a copy. If I make money using solidworks I'll buy a copy. Its like 5k? Not much for a corporation these days since angel investments are usually about 100k model, 1M prototype. Lawyers and salaries are expensive! I'd rather this project be open source for sure.

The best part is having my pilot model, my tires, brakes, and everything else modeled. When I want a new design I just delete the shell and draw another. Pilots and parts are all drag and drop in there.
 
Top