Open-source aircraft

No, plans are a tiny fraction of the cost of any homebuilt aircraft. The next major cost is that of the materials and engine, and the greatest cost is that of time.

Have you seen the ‘openez’?

I can see the logic. Bellancas are good, cheap, and the wings tend to rot… but the concept is wrapped around creating a non-certified aircraft, so the market is limited to places where that is a huge advantage. One angle might be to improve the plane by building a carbon fiber wing instead of a wood wing, but that’s not cheap.

Building a Bellanca wing will be a pretty big project, regardless…. In the US people would instead buy a run down Viking for $25K and restore it, C of A unchanged, but few do even that because the Viking’s fuel burn is high… so they’d rather put the effort into an RV with a four cylinder engine. I might be one of the few wackos who would do something like that

No, plans are a tiny fraction of the cost of any homebuilt aircraft. The next major cost is that of the materials and engine, and the greatest cost is that of time.

Have you seen the ‘openez’?

What would be interesting to me, would be advances in production methods. e.g. Could you 3d print jigs, slide carbon fiber rods into them then glue them all together with expanding foam before shelling off the jigs?

Unfortunately despite attempts by people like Burt Rutan, nobody has really managed to come up with a method of airframe manufacture that isn’t very labour intensive.

Looking at the ‘openez’ site, I realised that no authority will like the thought of opening the skies to an unknown design. In France it could be done, though, perhaps, there have been several one-off designs approved there. And I am afraid that is only one negative factor, several others have been argued to death here and elsewhere. One sees remarkably few homebuilt four-seaters, let alone 5-6, and there must be a reason for that. Also refer to the recent discussion about a very complex “home-built” and why none, or almost none, are flying in Europe

The one thing positive about a project like this is that it could offer choice/options: building the wing in alu OR with carbon-fibre spar(s) OR in a mould – either from carbon or from epoxy – like the early Europas. In the same way it could offer various engine options but always with the same firewall/bulkhead. But it would be a lot of work and only for a very limited audience.

@kwlf: to save on building time, Jim Bede came with the idea of building the wings from a kind of modules that slide on the spars and interlock to the next – but he gave up on the concept later.

Interesting idea! A couple of comparable aircraft come to mind – nothing open source but it might be interest8n* to see how others have tackled it.

The first is the Vans RV-10. It’s a kit and it matches the mission you describe very well but it’s not open source. On the Vans website, there is a cost estimator, which suggests a cost of about $125k, provided you resist the temptation to add avionics that you don’t really need for VFR. The engine cost alone is $47k (an IO-540) and they say It takes 2000+ hours to build one.

Another comparable aircraft is the Ravin500, which has a composite airframe based on the aluminium Piper Comanche, so it’s a kit based on a certified aircraft.

Even though the project is to be released under an open-source license, I think it’s very important to follow the certification specifications in their entirety and design new parts for a certifiable production process – not only to get a well-behaved aircraft and allow for an easier verification of airworthiness, but also to allow potential commercial production (the same way it works with Linux). It’s especially true if the new parts are to be mated to existing Bellancas. I happen to be collaborating with a small outfit here near Prague, which is moving (albeit very slowly) towards obtaining an EASA DOA (design organisation approval) for future “fringe” projects like this one (mostly giving a second life to old aircraft and engines), and it may be mutually beneficial to join our forces at some point.

In the uk you can only build 4 seater aircraft as far as I’m aware – not a problem if this is an option.

I know the LAA were open to the idea of an OpenEZ – you’d have to have a good versioning system to be sure you were building the version they’d approved – but I see no reason it shouldn’t be possible to get an approval for such a project.

I still find myself asking what the advantage of the design being ‘open’ is? If Vans designs were open would the resulting aircraft be substantially cheaper or quicker to build. Would the quality of the parts from 3rd party suppliers be better? I see no reason any of these things should be true.

Even closed designs such as the Luciole can have parts made by a number of 3rd party suppliers – I don’t understand the legal details of this but it’s quite common to find companies offering cowlings or canopies etc… for a number of designs.

What advantage do open source plans really offer?