If only there was some way to take the data from a few performance runs and the engine/prop altitude performance, and from that develop a chart that has multiple performance curves.

There must be a better name for such curves...

Well, yes, but you could say the same for the Raptor. The difference is in the professionalism and the way they are going at the project. You can criticize Peter’s ignorant fans, but I think that’s exactly what they are. It’s not that they’re stupid cheerleaders who should know better, they are clueless people who believe a convincing guy with a YouTube channel. Not many people can build a new airplane from scratch, so Peter has that much going toward his credibility. It’s not a stretch to think he’d have a crowd of people who don’t know better, following along and believing that he knows what he’s doing.

So, if he could get to FL250, maybe 210-220 kts. Heck, most would pay $130k for that. Well, except it has the useful load of 1 person and 10 gallons of fuel. Temps only start to stabilize when he pulls the power way back. I don’t think those turbos are going to get it done up high.

The guy did design, build and fly an airplane. Few of us can say we did.
I expect he has a program in mind to get the weight down. And improvements over current systems.
I do not think it impossible to evolve into a 200 kt airplane with diesel economy. I applaud the guy and hope XRaptor II becomes a viable machine.

Rocky

I guess that’s my point. Why allow the claims of 300 knots stay out there. If he said it was 200 knots and burns JetA for $250k it would be great and way easier to get behind.


But you are right he has accomplished a lot, too bad it’s overshadowed by ridiculous performance claims.


Mike

The good news is he is probably going to get it flying smooth enough to ask for the release of the escrows. $2 million more and 2 more years of posts.

I could never build a plane that I felt comfortable flying so in that regard, I respect Peter.

On the other hand, if I had to build a plane, I’d ask everyone who had experience and knowledge to help me....

Also, I enjoy this thread (200 pages now) and his videos no matter how much of a mess it is. I hope he sparks the aviation bug in someone and makes it meaningful in that way.

But it doesn't burn Jet-A. It burns diesel. From what I understand, there are enough differences between this engine and a piston engine designed to burn Jet-A that if you did run this engine on pure Jet-A, it would not last very long (hundreds of hours instead of thousands).

In order to run this engine on Jet-A and get any life out of it, you would have to add something to the fuel. So basically you'd have to haul around some amount of an additive that you could pour into the tank at every fill up.

Maybe he should have been using that additive as the ballast he's been adding?

Hi Don,

jet fuel, kerosene, diesel fuel. Same stuff with varying density and a few additives. If he's burning diesel it's to get more power to limp around the pattern. The power you get from a diesel engine is proportional to fuel density - you inject fuel based on volume per injection duration so higher density = more fuel mass injected.

Plenty of cropdusters save $$ by running their PT-6 on tractor diesel. That's fine down low in the hot weather where the fuel won't gel. But it's not going to work for a plane that aspires to the flight levels where it's cold. If Peter ever gets up there, he's going to need to run jet fuel or kerosene and he's going to lose power accordingly.

The only "additive" you might use to run jet fuel in an old tractor or volkswagen is something to improve fuel lubricity for the injection pump. But that goes for any modern ultra-low-sulfur diesel fuel. When running modern fuel in an old diesel engine it's a good idea to add a splash of automatic transmission fluid to the fuel, to avoid scuffing the injection pump plungers. But all modern diesels have specially coated plungers to tolerate poor lubricity fuel, including Peter's Audi engine.
(PS don't ever add ATF or any other oil to the fuel in a modern diesel truck or tractor - you'll poison the exhaust aftertreatment)

At my day job this has not been an issue for a long time. We sell so many engines to the military that lubricity-tolerant injection pumps became pretty standard across the whole yellow engine line back in the 1980's. It's a common requirement among the worlds militaries for all tractors, trucks, generators, etc to run on a single fuel - jet fuel.

Also very common to tap jet fuel for diesels in very cold climates. These diesel tractors at the bottom of the world have jet fuel in the tank.

The power and cooling issues are not going to be left alone. We’re talking as though this was the production model and it’s not. It’s not a matter of whether they will be resolved, but how. The turbos are installed incorrectly and inefficiency. Peter has been told that and not denied it. I’m sure it’s on his “to do” list for the next build, along with a revised cooling system that doesn’t involve a chest cooler in the frunk.

Will that get his numbers to where they were advertised to be? Of course not, but they may be good enough to sell the plane. The bigger problem would be the one that Don brought up about not being able to burn Jet A. If that’s the case then that’s a huge disadvantage in a cross-country airplane, and potentially a deal breaker that is nowhere near Peter’s radar.

I remember as a kid building a rickety soap box derby car with random crap from my dads garage. Every time I read this thread the Raptor reminds me of that experience.

It is not out there currently. He isn't taking any deposits and has removed all specs and performance claims from the website a while ago.

I really think that he has realized that this project will never claim even close to the numbers he originally proposed to sucker people in.
I think that he just wants to get it flying reasonably well, get some distance, and maybe get up to 10k, Then wrap it up and move on to something different.
If any of those claimed numbers were possible, some corporate would have already move in with capital and dumped money and brains to the project.
It is not. And will never be....
If Burt Ruttan could not do this... How in the world this guy thinks he could pull this off.
Dreams are good, and all should follow them.
For me the issue is when you start taking money from people. You are not a dreamer anymore, you become a con artist. ( because you have to know that those are ludicrous numbers, and if you don't it is worse, you are just incompetent)