A friend can also take lessons and did but they can't be charged...you have to do it for free. We worked out a trade....he worked for me on computers with no $$ exchanged.
Pierre,
I realize this is getting a bit off topic but I thought I would mention that the FAA does not consider working a trade to be acceptable, just because no money changed hands.
The FAR's say you can not receive "compensation" (it does not mention cash specifically).
There are instances were the FAA has issued a violation for this type of thing, it was fought in court and the FAA won.
One case that comes to mind is a pilot who was flying a jump plane for a jump school. He did not yet have his commercial license so could not be paid for flying. He was doing it for free to accumulate flight hours towards the ratings he was working on. The FAA considered that "compensation" because it would relieve him of the cost of some of those flight hours.
Now maybe they went after him because they didn't want someone without a commercial lic. flying for a commercial operation, but there are other instances similar to the one you mentioned.
Please don't shoot the messenger...just suggesting people be careful.
As for the question of primary training (as opposed to transition training for a pilot who already has a rating) in an experimental. The issue is related to compensation for the cost of the airplane, not the flight instructors time. All experimental operating limitations have a line that disallows use of the airplane for compensation. If you are using your own RV to get you private license, you would be paying an instructor for his time. If you were willing to let a friend use your RV to get his private license he could as long as he only pays for the instructor's time and fuel for the airplane. You can not be compensated in any way for the time he puts on the airplane.
The reason for the waver system that was mentioned is so that a qualified CFI that owns an RV can charge for transition training (instruction charge) and charge for the expenses related to providing the airplane (insurance, general maint. costs, etc.) He is not allowed to do the same for primary training for a student working towards a rating(this is outside of what is allowed by the waver) because this would be a way for someone to circumvent the FAR 135 regulations for a commercial use of the aircraft.
So as long as there is no compensation for the use of the airplane, anyone can do primary training in an experimental. If compensation is being paid for use of the airplane (experimental) it must have had a waver issued by the FAA, and then in that case it can only be for transition training, no primary training is allowed.