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#1
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Flanker vs F-15
I'm no aerodynamicist but I've been running some numbers and noticed some
interesting things. The SU-27 is credited with being more manueverable than F-15 and yet F-15 has a higher TTW number (except at gross) and a lower wing loading by a large margin (again except at gross). The SU should develope more body lift than Eagle, but at best it looks like a wash at low altitudes, with Eagle turning better than SU at altitude. Any thoughts? Am I missing something large here? The Su's lerx's and higher aspect wing should make a positive differance at low level and low speeds but I dont think it would make up for the other numbers. Eagle should have a 20% better wing loading and about a 14% better TTW number. -- Curiosity killed the cat, and I'm gonna find out why! |
#2
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"Boomer" wrote in message
... I'm no aerodynamicist but I've been running some numbers and noticed some interesting things. The SU-27 is credited with being more manueverable than F-15 and yet F-15 has a higher TTW number (except at gross) and a lower wing loading by a large margin (again except at gross). The SU should develope more body lift than Eagle, but at best it looks like a wash at low altitudes, with Eagle turning better than SU at altitude. Any thoughts? Am I missing something large here? The Su's lerx's and higher aspect wing should make a positive differance at low level and low speeds but I dont think it would make up for the other numbers. Eagle should have a 20% better wing loading and about a 14% better TTW number. The Su has a pull-through fuction on the fbw ISTR. Might be a factor? John |
#3
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John Mullen wrote: The Su has a pull-through fuction on the fbw ISTR. Might be a factor? Probably not since the the F-15C isn't FBW and only has an overload warning function. You can over G a F-15C. Michael Kelly, Bone Maintainer John |
#4
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yes Flankers have a switch which over rides the FBW limits, that's the only
way they can do the "Cobra" manuever. As I recall F-15s started out with hydro controls with FBW as back up, then later models went fully fly by wire. -- Curiosity killed the cat, and I'm gonna find out why! "Michael Kelly" wrote in message m... John Mullen wrote: The Su has a pull-through fuction on the fbw ISTR. Might be a factor? Probably not since the the F-15C isn't FBW and only has an overload warning function. You can over G a F-15C. Michael Kelly, Bone Maintainer John |
#5
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"Michael Kelly" wrote in message m... John Mullen wrote: The Su has a pull-through fuction on the fbw ISTR. Might be a factor? Probably not since the the F-15C isn't FBW and only has an overload warning function. You can over G a F-15C. Michael Kelly, Bone Maintainer Actually fly-by-wire aircraft can be over-Gd -- it happens to F-16s all the time. The F-15, while not "fully" fly-by-wire, has a primary flight control system that is FBW (called the CAS, or Control Augmentation System) and a hydromechanical backup system. |
#6
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R Haskin wrote:
Actually fly-by-wire aircraft can be over-Gd -- it happens to F-16s all the time. Yabbut, isn't that a case of a Lawn Dart pulling max G and then hitting turbulence, etc.? Jeff |
#7
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On Thu, 25 Mar 2004 02:44:04 -0600, "Boomer"
wrote: yes Flankers have a switch which over rides the FBW limits, that's the only way they can do the "Cobra" manuever. As I recall F-15s started out with hydro controls with FBW as back up, then later models went fully fly by wire. The F-15 started as conventional with conventional backup and an analog FCS. It eventually went to a digital FCS, but not to FBW. The E might be FBW, but the A-D aren't. Mary -- Mary Shafer Retired aerospace research engineer |
#8
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There are two really important questions:
1. What are the other odds? (AWACS, support aircraft, SAM defenses, range to bases, numbers on each side, etc.) 2. Who are the pilots? Both of these are quite critical to the equation. DEP |
#9
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R Haskin wrote:
Actually fly-by-wire aircraft can be over-Gd -- it happens to F-16s all the time. Agreed. The Bone is a 2 channel FBW on one side with a hydromechanical stability augmented system on the other side. There are no limiters on the FBW or stability aug so over G's happen all the time. Limiters on the 16 make it harder to over G but not impossible. The F-15, while not "fully" fly-by-wire, has a primary flight control system that is FBW (called the CAS, or Control Augmentation System) and a hydromechanical backup system. IIRC my F-15 test pilot former colleague described the F-15C as fully hydromechanical and the Echo's as you did. BTW saw you the other day on the history channel. Good interview. Cheers, Michael Kelly, Bone Maintainer |
#10
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Jeff Crowell wrote:
Yabbut, isn't that a case of a Lawn Dart pulling max G and then hitting turbulence, etc.? I could see too high of an onset rate, or pulling a turn as you decelerated through the sound barrier. The latter case would be a very good candidate if pulling a turn close to the limiter because of the forward shift in the aerodynamic center going from supersonic to subsonic. Jeff Michael Kelly, Bone Maintainer |
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