What do you mean very few? If as someone said they are that skilled at keeping black projects, the Lockheed comment does make sense. In producing aircraft to new designs for a different type of warfare there has to be a lot of prototype concept aircraft along the way and there just don't seem to really be that many in the case of some of the modern Stealth Aircraft so could these be kept secret at the Area 51 Airbase? We are talking in reality a massive leap in design and yet there don't seem to be that many failed designs. I know there are computer simulations etc, but still there has to be data gained from actual models, etc. to fuel that computer simulation properly.