Discussion in 'Aircraft Design / Aerodynamics / New Technology' started by Starman, Aug 27, 2009.
So why doesn't that flight hold the record for level flight? Maybe - just maybe - because it wasn't level flight?
Yeah, his name's Bruce Bohannon, and the plane is the Flying Tiger. And he doesn't hold the under whatever gross weight (C.1(b), 1000kg if you must ask) but the *ABSOLUTE* world record for horizontal flight by a piston engine aircraft. No, he wasn't limited by lack of pressurization. If you read about the flights (it was a series of flights) you'll find they were at the limits of engineering for performance at that altitude. Y'know, engineering - building stuff that the bookheads say should be possible?
OK, that's it. There is so much wrong in that statement - I give up. Really.
Flight altitude record - Wikipedia, the free encyclopedia
Read the entery for 1938 october 22
I'm sorry Pie_row, but I read this the same way Jim did...
In addition to saying that the details need verification of source (citation needed), it also says that Bruce Bohannon's flight was sustained "level flight", but does not make the same claim for the Caproni. Therefore, I would assume that at least part of the Caproni's altitude gain may have come from a zoom-climb maneuver.
Note that a zoom-climb can even be performed by a "draggy" biplane because at this altitude, the air is thin and the True Airspeed will be substantially higher. It may not be a big gain in altitude, but I suspect that those two big wings have enough bite even at that altitude to lift the plane into a ballistic trajectory.
An interesting aside regarding zoom-climbs: Spaceship One was launched from the White Knight at a lower altitude than the White Knight was capable of. This is because Spaceship One needed the slightly thicker air to efficiently complete it's transition from horizontal to vertical flight. A higher drop-launch altitude would have used more fuel and distance to make the transition. Once vertical, IIRC, the engines only powered it to about half (it may have been as little as a third) of it's total altitude, and then it coasted ballistically through the second half of its climb.
I love the aft-facing views of the boost in the Discovery Channel specials. Fantastic footage.
To make the additional 2782 meters with a perfect zoomclimb you need around 470 kts. Though that sounds like a lot it's probably around cruise for those aircraft (because it corresponds to 155 kts indicated) so it's a more than plausible story.
Besides that I have serious doubts whether that 1938 record meets the FAI requirements, especially the calibration of the altimeter.
Because a fault of 3% already gives you a altitude +/- 4000 ft, that might very well be the explanation.
Better check your facts. The Voyager preceded the Condor by several years and the Voyager engines were 4 cylinder.
Jim hitted the bottomline already:
I will not yet.
You're still not taking into account the power required to drive the compressor. That power is simply not there by far.
Let's approach is from the other side. Basically a turbo/supercharged combustion engine and a turbofan/prop are exactly the same, they compress the air, combust it and use the energy out of it to power the compressor. The residual power is used for turning the prop or fan in front. As for efficiency or limitations it doesn't matter at all whether you derive that power by linear or circular means.
So a turbofan or turbo-ed combustion engine are basically the same thing. Not too surprising that the highest operating combusion engines and the highest operating jet engines have roughly the same limitation, a good 15 kilometers, 18 max..
Would you be surprised if that Rotax had about 8HP power? (100HP, 1/50th of the pressure, max 4 boost)
So you want to use a 5/10 seconds lifetime, 5000/8000 lbs or so diesel to put it up to the same altitude as a RAMJET?
Let's be really blunt and direct.
Since you're going to do something most experienced people tell you is impossible and hasn't been achieved by anyone:
Do you think all those other people/engineers are so stupid, or is it simply that you're just brilliant in thermodynamics and engine construction?
As for myself, Jim has already proven that he's way more intelligent than I am
It's a pity your 'genius' doesn't extend to spelling and grammar.
Seriously, let's knock off the hyperbole, okay? This is becoming more than absurd, and posts like this, from guys like you, are seriously detracting from the discussions in this forum, IMHO. This isn't "Aircraft Design Fantasy Island". We actually try to talk about the real thing here.
First of all, 80,000 ft is the typically published altitude for the SR-71, but many sources (including pilots, which I have known several) place it quite a bit higher. Second, this really has no bearing on the discussion because most of the high altitude, high speed thrust comes from bypassing the air around the compressor and turbine and running the engine more as a ramjet than a turbojet. The turbine's role at this point was less about thrust and more about running the hydraulic and electrical systems.
Separate names with a comma.