What we have in the form of experimental airplane building is a great privilege that the rest of the world envies, with a couple of countries' exceptions.
Actually it is the low fuel prices and the low total hour by hour cost together with the widespread acceptance of GA that the rest of the (aviation)world envies
Hence the incredible growth in microlights (MTOW 472.5 kg) in in Europe in the last 20 years, low cost - no strangling regulations from the CAAs'. I don't know of a single country in Europe where you cannot build and fly your own airplane, experimental and microlights. Historically simplifyed "experimental" kind of rules emerges only when the "ordinary" rules and regulations becomes so complicated and restricted that it is impossible for amateurs/small companies to follow them for practical and/or economical reasons. In Europe there was a vacuum in amateur built airplanes after WWII an to the 50-60s when new relaxed regulations was needed. In the US, it seems to me that concerns regarding liability is one major motivation. All manufacturers are too scared of lawsuits to continue making certified carbs for instance, and this pushes people and the whole industry toward experimentals.
Anyway, I see this is an old thread/discussion, but it is very interesting. The 51% rule is really a paradox. One thing is to have the opportunity to build your own airplane more or less from scratch, which is good. Another thing altogether is being literaly
forced to build (at least 51% of) your own airplane, an airplane that has higher performance in all respects compared with ordinary aircrafts, and has relaxed certifications of the aircraft itself and it's equipment as well as relaxed maintenence procedures. At the same time it is used as any certified private airplane, and it can be sold to anyone.
It is quite obvious that the one and only reason for an aircraft like the RV-10 to be certified as experimental is because of the 51% rule. In all respects it compets head to head with privately owned high performance certified 4 seaters in the 2-400,000 $ range. There is nothing experimental about an RV-10. I don't know, but I would imagine that the main original reason for the 51% rule was to prevent people from simply mounting a Cessna 172 wing on a Cessna 172 fuselage together with a new engine, new avionics/electrics and new paint and register it as an experimental aircraft. But I really do not see the real difference between doing this and building a QB RV-10, except with the RV-10 you have manuals, drawings, it will be much cheaper and the end result will be much better.
In Norway, and I guess in most of Europe except maybe England?, experimental aircrafts also include restoration of more than 30 years old aircrafts. It is not restricted to kits, plans build and prototypes. The 51% rule is a bit different as well, since it applies to kits only, not the builder/owner. The owner and the builder can be two different persons, and the builder don't even have to build the plane himself either, only administrate and be in charge of the building process, but there can only be one single administrator. Usually though, the builder(s)/(administrator) and the owner is the same person.
Personally I just don't get it. To be able to build from scratch or kit - yes, to have that opportunity is great. But to restrict it so that 51%
has to be built, makes no sense whatsoever regarding certification and use, as long as the airplane is restricted from commercial use. An example here is the CH-601. It can be purchased ready to fly, almost ready to fly or as a slow built kit according to the European UL rules, this makes no difference regarding certification. It can also be built and registered as an experimental, but
only as a slow built kit. The experimental version can have higher MTOW, meaning larger engine and can in general be a much more complex aircraft with full IFR, but according to the law you cannot purchase it ready to fly and tested from the factory. I was thinking previously that this had something to do with laws and liability issues, but there are no such issues amongst the several 1000 of UL certified planes in Europe, so this cannot be it. Now I am thinking that the 51% rule smells more of sentimental and stubborn old men.
