Chris,

Diamond as part of the certification process choose the altitude for the service ceiling.
The regulations require certain performance at that altitude, and restart provisions.

There is no special regulations or A/C guidance about 18K which affects anything other than avionics.

In this case; Diamond choose 18K. Likely because going higher offers minimal speed boost and the planes very rarely fly there.


Tim

Chris,

Diamond as part of the certification process choose the altitude for the service ceiling.
The regulations require certain performance at that altitude, and restart provisions.

There is no special regulations or A/C guidance about 18K which affects anything other than avionics.

In this case; Diamond choose 18K. Likely because going higher offers minimal speed boost and the planes very rarely fly there.


Tim

so, here's the full quote referenced..
https://www.flyingmag.com/aircraft/dies ... evolution/

have fun with the new guy folks & btw, the wiki for the unmanned version flown by Israelis shows use of the fab Thielert diesel engines
https://en.wikipedia.org/wiki/Aeronauti ... _Dominator

Lets recap:
We haven't heard from our resident research expert since September.
A new research expert pops up a week later.
He is very mysterious and evasive about his work ( which has absolutely nothing to do with the aviation industry).
Apparently my tinfoil hat is getting a bit tight.

You would think he would be all over the PC12 announcement thread or even getting into the merits of the new nose cowling for it. If I flew a PC12 and was such an "expert" on aerodynamics, I would think that would be much more interesting than this little experimental that will never get past the testing phase.

If I had my picture taken in the right seat of a PC12, I wouldn’t reverse it. Nothing wrong with sitting on the right. Nothing wrong with not having a pilot’s license, either.

You would think he would be all over the PC12 announcement thread or even getting into the merits of the new nose cowling for it. If I flew a PC12 and was such an "expert" on aerodynamics, I would think that would be much more interesting than this little experimental that will never get past the testing phase.

I don't know if CC is MC

I like Mike C, I do not like Chris C, Plus Mike C is usually right we just don't always like how he presents his case. CC has been wrong way more than MC

I really doubt Chris C is who is says and even if he is there is something off.

Why would a PC-12 pilot that's such a expert come to BT to just get on the Raptor thread?

Something is fishy. LOL

Mike

Of course not. Just having fun. Mike logged in this morning, so he is still around. Probably laying low and laughing at the whole thread.
No idea who our new guy is, but I am fairly sure he's not who he says he is.

Of course not. Just having fun. Mike logged in this morning, so he is still around. Probably laying low and laughing at the whole thread.
No idea who our new guy is, but I am fairly sure he's not who he says he is.

Mike C would never utter the phrase "Class A certification". For a moment I thought we we switched to discussing diesel pushers.

Our resident expert would have actual data to back up his reasoning

Another way to look at the maximum range would be to apply the Breguet Range Equation and apply a few assumptions. Assume L/D=14 which is pretty generous. Also assume SFC=.3 lbs/HP-hr also optimistic, propulsive efficiency=85%, gross weight (W1)=3800 lbs, fuel 121 gal=811 lbs, where W2=final weight

Range=325.8*(Propulsive efficiency/SFC)*(L/D)*ln(W1/W2)

Works out to 3100 nm. So 3600 nm is not possible. This also assumes flying at L/D max which is slower than most want to cruise.

Yep. This really is basic "cocktail napkin analysis" and anybody with a basic understanding of math and aerodynamics can do it. That formula isn't a secret, neither are any of the approximate numbers you put into it, and anybody can take a calculator and play around with the numbers and figure out what it would take to achieve the advertised/promised range.

I'm still a fan of the guy for trying, but the napkin math has raised my eyebrows from the beginning.

I think if it was aerodynamically feasible with the amount of hp available, Burt Rutan would’ve already designed it. His Boomerang goes 2100nm doing 210kt at 24000ft. Sure, it’s a twin but it shows you need an advanced, unconventional aerodynamic design to hit the numbers Raptor is aiming for.