The objective is very important. You don't build an airplane because you want one faster or cheaper. Neither is the case. The kit won't be cheaper, and it'll take 1 to 2 thousand manhours, minimum, of your time (take the building time claim of any kit and double or triple it to get reality).
You build one for the experience of building one. A lot of ...
The big disadvantages of a kit: it will take you years to have an airplane ready to fly, and you'll be flying an airplane built by a novice builder.
The main advantage of a kit: you (often) don't need all the money up front. Buy the fuselage kit, build it. Then buy the wing kit, and build that. Not all kit planes are sold this way, but several are. No ...
The other answers are good, there's a couple of aspects that haven't been covered that I'll touch on in my answer.
Kitplanes have a higher rate of accidents overall than certified airplanes. There's a good article from kitplanes magazine that breaks down causes, it's not authoritative but it's extremely useful in showing the differences in accidents ...
No. The strength to weight ratio of PVC is poor compared to aluminum and you would end up with a very heavy, albeit cheap, machine, and will be even worse when compared to carbon fibre tubing, which would be the optimal choice performance-wise. Extruded aluminum tubing would likely be the best choice cost wise. Forget about building a plumb-O-copter.
You will need a fixed landing gear and a braced wing to keep your mass at your target of 40 kg. Expect a maximum L/D of not more than 10, maybe even 8.
You say that the flight mass will be 100 kg. The weight will be 980 N. 1/10 of that is 98 N. To arrive at a power from that will need a few more heroic assumptions. Your wing loading is probably 12 to 15 kg/...
That is a complicated process. You need:
A positive mold (mandrel) for the canopy.
A negative mold for the canopy frame. For a single prototype you can also use the unfinished fuselage itself.
A fuselage mold with a molded window sill.
First the fuselage positive mold core is built. From that the negative mold is taken, but also a negative mold only for ...
This has been done, but here are some things you'll need to consider.
Air-cooled motorcycle engines are designed to produce short bursts of peak power, and to be as light as possible. Lightness is an advantage for any airplane engine, but having an engine designed for brief bursts of high power is not. An aircraft engine has to operate for long periods at ...
I assume that this is for a Private Pilot - Helicopter license. I also assume you mean something like larger kit aircraft, not ultra-light helicopters like the Mosquito.
You can do this, but there are other conditions that must be met:
The aircraft must have completed it's flight test phase (this is usually the first 25-40 hours of operation)
The CFI must ...
I'm not a pilot, though I am an aviation enthusiast, and here are some of the pros/cons that have not been mentioned yet.
Kit plane pros:
Kit planes have experimental classification, which means you can add non-certified parts to the aircraft. This can be especially beneficial for things like exterior lights since non-aircraft LED headlights are cheaper and ...
In my experience using PVC to build scale models, PVC doesn't make a good construction material:
it's too flexible. PVC pipe will bend under its own weight.
the glue typically used to join PVC is pretty weak, impact loads will break the bond.
PVC is no where near stiff enough for a given weight. And its strength to weight ratio is poor. The structural efficiency of air machines is absolutely critical otherwise you are building a machine that may not fly at all.
Plus, do a search for helicopter ground resonance, especially watch some youtube videos of helicopters destroying themselves.
In the US, there is no requirement to use a type certificated aircraft to log hours for aeronautical experience. Nor is there a requirement to use a type certificated aircraft for logging instruction. Although, the aircraft can not be rented to nor by you. The aircraft would have to meet all the requirements for an experimental aircraft.