From: skunk-works-digest-owner@harbor.ecn.purdue.edu To: skunk-works-digest@harbor.ecn.purdue.edu Subject: Skunk Works Digest V4 #0 Reply-To: skunk-works-digest@harbor.ecn.purdue.edu Errors-To: skunk-works-digest-owner@harbor.ecn.purdue.edu Precedence: bulk Skunk Works Digest Saturday, 28 August 1993 Volume 04 : Number 000 In this issue: Re: The Right Airplane Re: The Right Airplane The Right Airplane - The Right Story See the end of the digest for information on subscribing to the skunk-works or skunk-works-digest mailing lists and on how to retrieve back issues. ---------------------------------------------------------------------- From: "Jim Batka" Date: Fri, 27 Aug 93 08:13:06 EDT Subject: Re: The Right Airplane >Yes, that actually happened. The aircraft was actually an 'NF-104' >and was a one-of-a-kind with a rocket mounted in the tail. >If you can get a copy, read Yeager's autobiography, he covers the >incident in good detail. Apparently, the inside of his helmet was >on fire, and he suffered some burns to his face. Was not the >high point of his life. Although I don't remember all of the story, here are some other things that I believe also happened. He also had a broken bone (I can't remember whether it was a leg, arm, or something else). I think his hands where also burned. By the time the aircrews got to him, he had folded his parachute and started walking back to base. As far as the rocket in the tail, this must have been in addition to the turbo jet engine. The record, I believe he was trying to break, was the max altitude for an airbreathing vehicle. He achieved this by climbing to some intermediate altitude and then applying max A/B, pulling the nose up and climbing until the engine died, after which he flew a mostly ballistic trajectory. The reason for the crash was the turbo jet died (due to the thin air) and he was unable to restart it. I'm sure someone will correct me if I'm wrong in any of these details (: . Jim B. ------------------------------ From: freeman@MasPar.COM (Jay R. Freeman) Date: Fri, 27 Aug 93 08:33:15 -0700 Subject: Re: The Right Airplane I think I remember that one thing the NF-104 was supposed to do was to check out the use of reaction-control thrusters for maintaining attitude. The intent was to fly a high trajectory and use the thrusters at peak altitude, where the air was too thin and the bird too slow for aerodynamics to matter much. Once the NF-104 itself was well-understood, it could be used for training astronauts, and so on. There's a key technical problem here. If you drop a cigar out the window, it will tend toward an equilibrium falling position in which it is flat -- long axis at right angles to the velocity vector -- rather than (either) point first. NF-104s resemble cigars, and indeed, flat-spin conditions in many aircraft are very stable and in essence impossible to recover from without special gadgets. One key data point for the NF-104 flight profile was, how deep could you go into the atmosphere on the "down" side of the trajectory and still have the relatively wimpy reaction-control thrusters overpower the ever-increasing aerodynamic moments that tend to put the aircraft in a flat spin. On Yeager's flight, they found out the hard way -- the aircraft was positioned with thrusters at a high angle of attack on the "down" side, and got too deep to recover with the thrusters. Yea, verily, it flat-spun. Ho, hum. The NF-104 was equipped with a "spin 'chute", a parachute attached to the tail, for just such occasions. Yeager deployed it, and instantly the aircraft was pointing into its own relative wind, happily no longer spinning. That's where the problems began. It turned out that between the long ride at high altitude, and the low slipstream through the intakes in the flat spin, the NF-104's turbine engine had flamed out and spun down to near-zero RPM. Again, no big deal, one can always restart. But it also turned out that the NF-104's aerodynamic control surfaces were operated hydraulically, and the hydraulic pump was driven by gearing off the engine. No RPM -- no hydraulic pressure -- no control. What's more, the control surfaces have "stow" positions into which they go when there is no hydraulic pressure, and the stow position for the elevator (actually, wasn't it a flying tail?) was -- ta da -- full up elevator. So when Yeager jettisoned the spin 'chute (a one-shot unit), the NF-104 neatly went right back into its flat spin. Yeager spent some twelve miles (vertical) trying diverse other techniques for spin-recovery -- not many with no control surfaces working -- and finally punched out. Then things got moderately serious, for the NF-104 ejection seat relied on slipstream over fins to keep it correctly oriented during the eject-and-deploy-parachute sequence. In the few moments between the seat leaving the aircraft and Yeager being booted out of the seat, the seat had turned upside down, because the slipstream in the flat spin was too slow to keep it oriented. So from the bottom up we had Yeager, his deploying parachute, and the ejection seat, with the still-spinning NF-104 nearby and a major hazard in its own right, since it wasn't falling very fast or moving away -- a flat-spinning aircraft is just like a buckthorn seed (for the New Englanders among us). Yeager's luck held in the large -- he did not collide with the NF-104 -- but failed in the small: As his parachute deployed, the ejection seat fell through it, damaging both the parachute and several shrouds. The seat also hit Yeager -- the hot rocket nozzle which had provided thrust for the eject hit his helmet, sliced open his faceplate, cut his face, and set his helmet on fire -- remember it's pure oxygen inside. Yeager shut down the oxygen supply to control the fire, and got his 'chute open enough to work reasonably. Blood protected his eyes and much of his face from the fire. I have read about this in one or two places, and once heard Yeager speak (at a paid-admission event for pilots) and tell the tale himself. I hope I have not messed up too many of the details. I am sure that someone will correct me if I have, though. -- Jay "Mind Like a Packrat" Freeman ------------------------------ From: Rick Pavek Date: Fri, 27 Aug 1993 11:11:37 -0700 Subject: The Right Airplane - The Right Story Jay, Sounds right on to me... Thanks, Rick SR-75/XR-7 _|_*O*_|_ | Rick Pavek \ __|__ / | HA!! kuryakin@halcyon.com \______-/ [_] \-______/ | Ruby - \-\___/-/ | Galactic Gumshoe ------------------------------ End of Skunk Works Digest V4 #0 ******************************* To subscribe to skunk-works-digest, send the command: subscribe skunk-works-digest in the body of a message to "listserv@harbor.ecn.purdue.edu". If you want to subscribe something other than the account the mail is coming from, such as a local redistribution list, then append that address to the "subscribe" command; for example, to subscribe "local-skunk-works": subscribe skunk-works-digest local-skunk-works@your.domain.net To unsubscribe, send mail to the same address, with the command: unsubscribe skunk-works-digest in the body. Administrative requests, problems, and other non-list mail can be sent to either "skunk-works-digest-owner@harbor.ecn.purdue.edu" or, if you don't like to type a lot, "prm@ecn.purdue.edu". 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