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Raptor Composite Aircraft

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sming

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There are also dry clutch versions, but they tend to get broken after 60.000km (~40k miles) if you have lots of stop and go and are not considered exchangable.
That's totally part of the raptor business plan!
Endless supply of almost brand new v6 diesel from a certain german brand to power the 1500 orders of the airplane ;)
 

cheapracer

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We know the brakes are dragging when taxiing, but not how much. So estimating power from acceleration has a big unknown variable.
Not a lot after the initial roll, and jet guy wasn't including the initial roll in his calcs.

Pull your handbrake on 20%, start to drive and you will immediately feel the drag of course. Pull it on that much at 60mph, you won't notice much difference, if at all.

That I have seen, he has done nothing to cure his brake drag issue, I expect another burnt set of pads and glazed discs before long.

The drag is likely the case of no free play built into the split brake system..
 

BBerson

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Differential brake drag can be significant on an underpowered aircraft on takeoff. My Grob refuses to accelerate with differential brake applied in a crosswind. It accelerates quite briskly at the start. Then while approaching liftoff speed the acceleration is not even perceptible and takes a bunch of runway. Same with seaplanes and other loaded aircraft. If the aircraft is still accelerating nicely at takeoff speed it should climb out when the wheels break free.
 

Rod Schneider

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Not a lot after the initial roll, and jet guy wasn't including the initial roll in his calcs.

Pull your handbrake on 20%, start to drive and you will immediately feel the drag of course. Pull it on that much at 60mph, you won't notice much difference, if at all.

That I have seen, he has done nothing to cure his brake drag issue, I expect another burnt set of pads and glazed discs before long.

The drag is likely the case of no free play built into the split brake system..
The Wasabi video mentions that the rudder pedal geometry makes it very difficult to apply rudder without inadvertently applying the brakes..
 

231TC

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The A/C compressor is belt driven by the engine..
Thanks. Not sure what made me think it was electric, but the issue is the same with it engine driven. If he didn't program it to disconnect the belt pulley clutch at low RPM that will stall the engine when AC kicks on, it wouldn't surprise me at all if he didn't do it for WOT either.
 

BBerson

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I just manually flip the AC off on my car going up a mountain pass. I bet Peter figures a test pilot could do that on a prototype.
 

BJC

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I just manually flip the AC off on my car going up a mountain pass. I bet Peter figures a test pilot could do that on a prototype.
I drove a VW Diesel Rabbit for 200,000 + miles, so I am familiar with switching the AC off before pulling out into traffic.

An AC compressor driven from the engine is an unnecessary potential failure point while proving the airframe and engine. The belt should be removed for the first 50 - 60 hours of flight.


BJC
 

231TC

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There was also the option of not installing AC on the prototype to begin with, but that's not how PM operates. That's another answer to the question, "Why is this thing so heavy?"
 

231TC

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I just manually flip the AC off on my car going up a mountain pass. I bet Peter figures a test pilot could do that on a prototype.
Of course they could, but should they have to? It's easy enough to make the plane do it for you so the pilot can focus on more important things.
 

Voidhawk9

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But you won't even notice the A/C load with '400hp+' available!
Gotta cross that bridge first, I think.
 

TFF

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No AC, no cup holders, what is the point? It’s already cast in stone. Done. No what if’s. Just waiting on real flying. The only thing left. 316 pages have spent times on the what if’s and if I was in charge. No opinion is new now. You ain’t getten nothen else. Fly or crash is all that’s left.
 

231TC

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He can do any number of things for the production version, including delete the AC.
No need for your previous insulting comment that he is not smart.
That's a totally backward approach. Generally successful projects start with a bare bones proof of concept and add luxuries to the production version, rather than start with everything you could ever want and later subtract from the production version.

I didn't say he isn't smart. I said I wouldn't bet on him being smart enough to cut the AC off at WOT. That comes from his numerous other oversights, including that one involving the AC and throttle.

Focusing on the technical, not the person, but all these technical issues do happen to come back to one person, so it's tough to separate them.
 

cheapracer

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and have no involvement in.
I believe the outcome of a very public build like this affects our hobby, poorly, in my estimate, and that's where our "involvement" lay.

About the time that I believe this project will leave it's stain, not so long after I hope to be entering the market, so you might appreciate that I am quite underwhelmed by that prospect.


I didn't say he isn't smart.
Strictly within the boundaries of the Raptor project, I'd go with "not smart".
 
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