A key part of the “homebuilt/experimental” concession is that the builder is going to be extra careful, because he doesn’t want to kill himself.
That is why there are, on most registers, limitations on the subsequent owner.
Many threads here previously – example
I agree with mh. A good builder may be a very talented craftsman and produce a beautiful airplane exactly to the print, and a bad builder will produce an ugly one. But in either case, craftsmanship won’t win over a messed up aerodynamics or poor rudder harmony or a Vso of 85kts. Whether you have buit it or not, stepping out of a PA28 or a C172 and into this thing will be equally dangerous, because those are things craftsmanship has no impact on, only the prints do. It’s a systemic problem, not an execution problem.
It is simplistic to just forbid sale of an experimental to the next guy. What you need is a few chapters in the POH so you know what you are embarking on and do a proper transition training.
mh wrote:
As I have said: It is perfectly possible to build a very good performing, good looking, safe aircraft from a kit, the Van’s are a very good example.
Even so there are pitfalls that you won’t find in the certified world. A friend recently bought a Van’s RV6, and during his comprehensive upgrade for the plane (fitting EFIS etc) discovered the very nice looking steel braided flexible fuel hoses installed by the builder were designed for water, not for hydrocarbons. At some point it’s likely the fuel would have perished the hose inside the braiding (where you can’t see it) leading to possibly a serious in-flight fuel leak or engine stoppage.
Fortunately he’s an A&P/IA, recognised the problem, and could replace the plumbing with something designed to carry fuel.
That really sounds like an amateur error. Even though I know nothing about building airplanes, I have gathered from some accident reports that fuel lines need to conform to certain specifications also depending on the fuel type. But it may be hard to catch such issues if you are the second owner.
It’s a good Q whether this is better or worse than the clear plastic hoses used on some kits for fuel. Moreover these run inside the cockpit. They are the sort of hoses one would use to feed air into an aquarium. I don’t understand how saving money on this is worth it, given how cheap hoses are compared to say a £80k purchase cost of a *fox.
Previous threads here and here, and some others.
The RVs I have seen have been well built.
Peter wrote:
The RVs I have seen have been well built.
At least as far as you could see from the outside. The danger lies with those bits that you can’t see. What if the builder ran out of epoxy during a weekend session and went to the next car parts dealer for an extra bucket of resin with unknown properties ("I will use this only to glue some minor parts so it does not matter…. "). Next weekend he does not remember which bucket is which and uses the car-repair resin to attach his elevator…
Can you tell by looking that every bolt, every rivet, every bracket made from aluminium is of the correct specification? Or did he again use auto parts here and there because he thought these bits will not see large forces during operation?
I would only consider buying an aircraft built by someone else if the building is documented the way I would do it myself: Keep a sample of every bucket of resin and write down, which batch resin was used in what parts of the aircraft, keep a sample of every sheet of aluminium, keep samples of every type of fastener used on the plane, and so on.
Well, of course, all true, and if I knew of horror stories (which I do) they would probably not be for publication 
Well, I did fly in one RV and you could stick a finger out through the gaps. And his elevator trim linkage fell off 2 weeks after the flight. My reference to hoses was that the RV kit seems to come with the good ones (or does currently).
The biggest issue seems to be that nearly all homebuilts were the only plane the builder ever built, before his wife went off with the milkman/postman/etc while he was spending the 3000hrs in the shed 
So he learnt all he knows on that one plane – which you are about to buy.
The second biggest issue is that one is not allowed to talk about this. There is a name for this phenomenon in social science… something to do with criticism of minorities… even though homebuilts are numerically probably not a minority at all.
The third one is that a prebuy is difficult because you can’t check what is not visually obvious (wrong resin, or even wrong hoses unless they really are the aquarium type). But also I think most people that turn up to do a prebuy are not aware of registration / maintenance privilege / basing limits issues. I have this not from EuroGA (loads of threads here) but from real owners.
Don’t all current “resin” kits come with all the resin parts already made? It would be a lot of work otherwise, requiring a lot of skill to achieve the consistent properties.
RobertL18C wrote:
If there is an experimental which can match the SM SF260D then would be interested. OK the rear seat is for a petite passenger, but otherwise 180 KTAS, mil spec, IFR and +6/-3G.
But the runway requirement is considerable, and so you need to base it at an airport with a long hard runway. It’s a compromise, as usual.
Peter wrote:
Don’t all current “resin” kits come with all the resin parts already made?
Some do, some don’t. A very long time a ago I briefly considered building a “Quickie” (https://en.wikipedia.org/wiki/Rutan_Quickie) together with a colleague. The kit would only have contained shaped styrofoam cores for the four wings which one would have had to cover with glass and resin himself.
But even the kits with prefabricated glass- or carbon-fibre parts require those parts to be glued together. Use the wrong type of resin (or not enough or too much of it, which is even worse than not enough) and your whole aircraft will be several g’s short of the design loads…
PS: And then there are a lot of homebuilts which are built from plans alone, with very few parts supplied by the designer.
and PPS: This is a short Youtube video of a model aircraft coming apart on it’s own. It is special in so far as this is a half scale Saab Gripen and about the size of a typical passenger carrying homebuilt. Built under official supervision and almost to the same specs as a real aircraft…
Obviously the wrong type of resin was used for attaching the vertical fin:
If you watch it in slow motion, the vertical fin doesn’t come off as a single part, first it seems to begin an oscillation to the left, then the rudder disintegrates as the fin returns back to the centre, then the remainder of the fin disintegrates into matchwood. About 3/4 second later the aircraft violently pitches up and the rest of the structure fails. It looks like bending forces did it in, rather than a simple glue failure.
Also notable that this model is a great deal lighter than a homebuilt of the same size, so it contains much less structure (the payload is of course lower too).
