wb9omc@ecn.purdue.edu (Duane P Mantick) (11/07/90)
From: wb9omc@ecn.purdue.edu (Duane P Mantick) >From: ehr@uncecs.edu (Ernest H. Robl) >Now, for a question that I didn't get around to asking anyone at the >airshow: Some of the modern *AIR FORCE* fighters have tailhooks. Are >these ever used? If so, when, where, how? Thanks. This is true. In fact, the F117A has a tailhook. It has been said that this is for emergency stops only, although I haven't seen any definative material *yet*. Most people are of the train of thought that the F117A is too fragile for a carrier landing, if that is what you are thinking of. Some of the impetus for this may go back to some Lockheed tests on the F104 Starfighter done for the West German Air Force many years ago - in this case, Starfighters were stopped in short distances by arresting cables that grabbed the landing gear; no tailhooks. The tailhook is considerably less likely to cause problems than a straight-out gear snag, i.e., if you snag the landing gear unevenly you will stop unevenly and who knows how that will end up...... It may be that having an ability to slow a landing aircraft via the tailhook is desirable if you are trying to design "stealthy" aircraft. As the designer, you could then leave out things like thrust reversers, massive brakes, etc., meaning overall, less metal to generate radar returns *even if* the plane is in-flight. As a guess, I'd suspect that a tailhook, even a big metal one, can be hidden inside a radar-absorbing compartment fairly easily. There are several books about the F117A that are just now becoming fairly available....keep an eye out for them. Duane
shafer@skipper.dfrf.nasa.gov (Mary Shafer) (11/16/90)
From: Mary Shafer <shafer@skipper.dfrf.nasa.gov> From: wb9omc@ecn.purdue.edu (Duane P Mantick) >From: ehr@uncecs.edu (Ernest H. Robl) >>Now, for a question that I didn't get around to asking anyone at the >>airshow: Some of the modern *AIR FORCE* fighters have tailhooks. Are >>these ever used? If so, when, where, how? Thanks. The tailhooks on Air Force planes are used for both approach-end and departure-end arrestments, when there are gear problems. The throttles are in IDLE and the pilot has reduced the landing weight (jettisoned stores, for example). Navy planes are used for approach-end arrestments, as a normal procedure. The throttles are in MIL or MAX and the plane may be carrying stores. Obviously the Navy plane is going to have a lot more energy. I just went down to the hangar and looked at the F-15 and F-18 tailhooks (the sacrifices I make for this group :-). The F-15 is larger and heavier than the F-18 but its hook is noticeably smaller. > This is true. In fact, the F117A has a tailhook. It has been said > that this is for emergency stops only, although I haven't seen > any definative material *yet*. Most people are of the train > of thought that the F117A is too fragile for a carrier landing, > if that is what you are thinking of. In accordance with USAF policy the tailhook is for for emergency arrestments only. This isn't a Navy plane, so no provision would have been made for carrier landings. (Just like the F-15, for example.) BTW, the F-117A is a big aircraft. Think F-111, not F-16. > Some of the impetus for this may go back to some Lockheed tests > on the F104 Starfighter done for the West German Air Force many > years ago - in this case, Starfighters were stopped in short > distances by arresting cables that grabbed the landing gear; > no tailhooks. The tailhook is considerably less likely to > cause problems than a straight-out gear snag, i.e., if you snag > the landing gear unevenly you will stop unevenly and who knows > how that will end up...... This wasn't done just for the German Air Force, it was done first for USAF, since all military F-104s have hooks. Acceptance testing includes demonstration of all the systems on the aircraft; USAF won't take your word for it that the hook works, you have to show them it works. The F-15 Dash-1 has a table of abnormal gear configurations requiring arrestments. Arrestments are not _normal_ procedures; they're done only for emergencies. In fact, they're not even done for all emergencies. Sometimes you make an arrestment, sometimes you don't, and sometimes you eject. > It may be that having an ability to slow a landing aircraft > via the tailhook is desirable if you are trying to design > "stealthy" aircraft. As the designer, you could then leave > out things like thrust reversers, massive brakes, etc., meaning > overall, less metal to generate radar returns *even if* the > plane is in-flight. As a guess, I'd suspect that a tailhook, > even a big metal one, can be hidden inside a radar-absorbing > compartment fairly easily. The airplane has to be landable without arrestment. Otherwise what you would do were the arresting gear not working or the field closed? You don't eject just because of fog at the base. Fighters and bombers don't have thrust reversing. Some have drag chutes, though. -- Mary Shafer shafer@skipper.dfrf.nasa.gov ames!skipper.dfrf.nasa.gov!shafer NASA Ames Dryden Flight Research Facility, Edwards, CA Of course I don't speak for NASA "A MiG at your six is better than no MiG at all"--Unknown US fighter pilot
tek@CS.UCLA.EDU (Ted Kim (Random Dude)) (11/17/90)
From: tek@CS.UCLA.EDU (Ted Kim (Random Dude)) In article <1990Nov16.053023.22480@cbnews.att.com> shafer@skipper.dfrf.nasa.gov (Mary Shafer) writes: > ... >Fighters and bombers don't have thrust reversing. Some have >drag chutes, though. Don't some versions of the Tornado have thrust reversers? -ted Ted Kim Internet: tek@penzance.cs.ucla.edu UCLA Computer Science Department UUCP: ...!{uunet|ucbvax}!cs.ucla.edu!tek 3804C Boelter Hall Phone: (213)206-8696 Los Angeles, CA 90024 FAX: (213)825-2273
megazone@wpi.WPI.EDU (MEGAZONE 23) (11/19/90)
From: megazone@wpi.WPI.EDU (MEGAZONE 23) In article <1990Nov16.053023.22480@cbnews.att.com> shafer@skipper.dfrf.nasa.gov (Mary Shafer) writes: >Obviously the Navy plane is going to have a lot more energy. I just >went down to the hangar and looked at the F-15 and F-18 tailhooks (the >sacrifices I make for this group :-). The F-15 is larger and heavier >than the F-18 but its hook is noticeably smaller. For a dramatic comparison look at the difference between the YF-17s gear and hook and the ones on the F/A-18. One of the major modifications was to beef up the gear quite a bit. >Fighters and bombers don't have thrust reversing. Some have >drag chutes, though. Well in general they don't. But most of the Swedish planes do and so does the Tornado. ############################################################################### # "Calling Garland operator 7G," EVE Email megazone@wpi.wpi.edu # # MEGAZONE, aka DAYTONA, aka BRIAN BIKOWICZ Bitnet Use a gateway. Sorry. # ###############################################################################
d9bertil@dtek.chalmers.se (Bertil Jonell) (11/19/90)
From: d9bertil@dtek.chalmers.se (Bertil Jonell) In article <1990Nov16.053023.22480@cbnews.att.com> shafer@skipper.dfrf.nasa.gov (Mary Shafer) writes: > ... >Fighters and bombers don't have thrust reversing. Some have >drag chutes, though. Saab 37 Viggen (In all configurations: Figher/Attack, Attack/Fighter, Ocean Recon, Photo Recon and 2seat Trainer) use thrust reversing. The reason is that it has to come to a full stop in a very short length of runway to fit into the Swedish system of basing the entire airforce on slightly modified roads... I would guess that the entire apparatus for reversing thrust weighs a lot, and this weight will be dead weight in the air. Saab 39 Gripen (JAS-39) is said to use high-efficiency brakes to achieve the same goal without wasting that much weight. -bertil- -- "Words on the net aren't usually worth the paper they are written on."
dvlssd@cs.umu.se (Stefan Skoglund) (11/20/90)
From: dvlssd@cs.umu.se (Stefan Skoglund) About the Swedish Air Force and theirs Viggens. In the jetpipe of the Viggen you will find 3 triangulary sheets of steel folded in the wall at the inside. At touchdown the sheets goes into the jetstream and turns it forward thru 3 openings. The engine is a RM8 built on a license by Volvo Flygmotor in Trollhaettan. The RM8 is a license built JT8D. The EBK is Swedish-developed. The result is this : It takes about one minut from start to 10000 m. The EBK has 3 zones. The takeoff length is about 600 m You can cut it a little if you want. The landing langth is about 400 m. This is necessary to make the Swedish basing tactic work. We have a frosen lake up in Northern Sweden. A kolon with some snow-plough, fuelcar, some cars with technicians, ammunition and so on. They start to put up a landing strip and some service spots on the ice. The engine is a little picky about FOD. Immediately then the srip is clear. One kilometer is more than enough. 2 JA-37 ( Airplane-System nr 37 version Jakt (Fighters) with a limited attack-cap ) lands. They get refueled, reloaded and takes off. Total time about 20 minutes from wheels down to take off. Upon war and under exercises everyone and everything will deploy at war-bases. Some are the same as peace-bases, some are civilian and some are only for war. The war base is big. In the middle you have one main runway and connected with it bye taxing-lanes a number of service places. The newest bases has all this and two or three a little unusual wide and straight swedish roads to land at. A plane is inbound to the base. She gets a service place allocated. A squad with 3 enlisted men, 1 cinc, 1 tech and some fuel is being sent out. At touch-down the pilot will find a flight-controller ass on a motorcycle waiting. He will then take him to just his service-place. The whole purpose is this : if the enemy want to hit our air-bases he want get anything for his work. The JAS 39 Gripen is fitted with a RM12. It is a F404 equiped with a Swedish EBK. No Thrust reverser due to the heavy use of plastics and carbon fiber. You wont find much metal in it. Under the well known crash the structure cleared it with not so big damage. A bit of the wing, fin got broken. One of the Viggen prototype got in a crash too. The reversing system didn't shut symmetricaly so she went out in the grass because of non-symmetrical braking forces. Thanks for me. replies to dvlssd@cs.umu.se