jeff@aplcomm.jhuapl.edu (JEFF NANIS ) (03/08/91)
From: jeff@aplcomm.jhuapl.edu (JEFF NANIS ) There have been a number of threads concerning the ease with which land-based aircraft can operate off of carriers. The following is a letter from the back of AW&ST (March 4, 1991) which gives the best explanation I have seen: "Converting an advanced tactical fighter candidate into a carrier-based A-12 replacement is more complex than suggested... New, heavier landing gear will be required. Carrier aircraft have landing sink speeds of 26 ft/sec, while those of comparable land-based aircraft are 8-12 ft/sec. Catapulting and arrested landing systems must be provided. This equipment is not just bolted on; carry-through structure must accommodate vertical landing loads, and fore and aft launch and recovery loads up to 6 g. The new wings likely will require folding provisions to ease deck handling and stowage aboard ship. Tie-down requirements will be more severe due to high winds and a moving deck. The whole aircraft structure will have to be examined for compatibility with the sonic and thermal environments near jet blast deflectors. Materials must be examined due to the more corrosive atmos- phere aboard ship. A significant weight increase will accrue. Increased weight equates to increased takeoff and landing speeds, so aerodynamic means must be found to keepaircraft performance requirements within carrier catapult and arresting gear requirements. ----Huntley H. Perry, Laytonsville, MD" I hope this resolves some on-going questions.
wab@uunet.UU.NET (Bill Baker) (03/13/91)
From: igor!yoda!wab@uunet.UU.NET (Bill Baker) In article <1991Mar8.021800.7056@cbnews.att.com> jeff@aplcomm.jhuapl.edu (JEFF NANIS ) writes: > > >From: jeff@aplcomm.jhuapl.edu (JEFF NANIS ) > > There have been a number of threads concerning the ease with which >land-based aircraft can operate off of carriers. The following is a letter from >the back of AW&ST (March 4, 1991) which gives the best explanation I have seen: > > "Converting an advanced tactical fighter candidate into a carrier-based A-12 replacement is more complex than suggested... > New, heavier landing gear will be required. Carrier aircraft have >landing sink speeds of 26 ft/sec, while those of comparable land-based aircraft >are 8-12 ft/sec. Catapulting and arrested landing systems must be provided. >This equipment is not just bolted on; carry-through structure must accommodate >vertical landing loads, and fore and aft launch and recovery loads up to 6 g. Isn't one of the advanced fighter candidates incorporating thrust vectoring? It seems like I read this in an article. Wouldn't that permit much lower sink rates for carrier landings? The main problem of converting land-based aircraft, historically, has been the airframe and landing gear relative weakness. I've always assumed that the reason the F-4 converted so easily to carrier flight was that it was built like a tank anyway. I would think that, regardless of whether they procure a version of the ATF, the Navy would insist on thrust vectoring on the next generation of carrier aircraft. The weight savings from airframe downgrading could translate into much more range, more room for weapons and avionics, etc. The Navy (well, the Marines) have experience with thrust-vectored fighters with the Harrier. The technology is proven and mature. Beyond fighters, I would think that other carrier-based aircraft could benefit. When the time comes to replace the E-2, why not design a new radar platform with real STOL characteristics? The old Boeing YC-14 was a pretty good-sized plane with incredible STOL capabilities. Besides, I always wanted to see if it could take off from a carrier.
john@ssd.Kodak.Com (John Hall (726-9345)) (03/13/91)
From: john@ssd.Kodak.Com (John Hall (726-9345)) In article <1991Mar8.021800.7056@cbnews.att.com> jeff@aplcomm.jhuapl.edu (JEFF NANIS ) writes: | There have been a number of threads concerning the ease with which |land-based aircraft can operate off of carriers. The following is a letter from |the back of AW&ST (March 4, 1991) which gives the best explanation I have seen: | | "Converting an advanced tactical fighter candidate into a carrier-based A-12 replacement is more complex than suggested... ... <many good reasons deleted> But certainly possible. The land-based BAE Hawk has recently been modified to be a carrier-based trainer for the USN.
arthur@Eng.Sun.COM (Arthur Leung) (03/14/91)
From: arthur@Eng.Sun.COM (Arthur Leung) >From john@ssd.Kodak.Com (John Hall (726-9345)) >In article <1991Mar8.021800.7056@cbnews.att.com> jeff@aplcomm.jhuapl.edu (JEFF NANIS ) writes: >| There have been a number of threads concerning the ease with which >|land-based aircraft can operate off of carriers. The following is a letter >from the back of AW&ST (March 4, 1991) which gives the best explanation I >have seen: >| "Converting an advanced tactical fighter candidate into a > carrier-based A-12 replacement is more complex than suggested... > ... > <many good reasons deleted> > >But certainly possible. The land-based BAE Hawk has recently been >modified to be a carrier-based trainer for the USN. true, but it wasn't without some trial and tribulation. :o) from the feb 25, 91 issue of aviation week: "if the program succeeds, the T-45 will be the first land-based aircraft converted for carrier operations at least in recent memory," koehler (capt. richard e., naval air systems command's program manager) said. the navy had believed the goshawk was merely a low-risk derivative of the british aerospace hawk aricraft. initial stages of the flight test program revealed five major problems - with stability, control, and engine performance - that made the existing aircraft unquitable for carrier operations and set back the program at least 2 years. ... 60% of the internal structure of the goshawk will differ from the hawk. ... structural changes were not stumbling blocks for the T-45, but attaining requisite flying qualities were..... it's a pretty interesing article (apologies to the gentle moderator if i quoted too much). if you have access to avweek, take a peek at it - it's an educational article. -- arthur Disclaimer: if i knew anything, why would i be reading this newsgroup?
v059l49z@ubvmsa.cc.buffalo.edu (Paul C Stacy) (03/14/91)
From: v059l49z@ubvmsa.cc.buffalo.edu (Paul C Stacy) In article <1991Mar13.003648.7991@cbnews.att.com>, igor!yoda!wab@uunet.UU.NET (Bill Baker) writes... >and landing gear relative weakness. I've always assumed that the >reason the F-4 converted so easily to carrier flight was that it was >built like a tank anyway. You seem to be mistaken here. The F-4 started out as a Navy aircraft that the Air Force decided to buy for themselves. I believe that (at least the early AF versions) they still have the wing- folding system used by the Navy. Paul "Joe Friday" Stacy
henry@zoo.toronto.edu (Henry Spencer) (03/14/91)
From: henry@zoo.toronto.edu (Henry Spencer) >From: igor!yoda!wab@uunet.UU.NET (Bill Baker) >... I've always assumed that the >reason the F-4 converted so easily to carrier flight was that it was >built like a tank anyway. You have it backwards; the F-4 was a carrier aircraft from the start. It was built for the Navy, and then adopted (under protest) by the USAF. Changes for USAF service were pretty minimal: fatter tires, bulged wheel-well doors to accommodate the tires, USAF radios, and the slightly different USAF oxygen system were about it. Adopting originally-land-based aircraft for carrier service is, uh, more challenging. All the more so if you're also fighting a Navy establishment that prefers developing its own aircraft. On reflecting on this, it occurs to me that there has actually been quite a bit of USN->USAF traffic and almost nothing in the other direction. Sidewinder was a Navy missile, and I think Sparrow was too. In aircraft, apart from the Phantom there is the A-7, the Skyhawk (yes, it did see some USAF service), and the revamped Skywarrior that became the B-66. I can't immediately think of anything since the Sabre that has gone from the USAF to the USN. -- "But this *is* the simplified version | Henry Spencer @ U of Toronto Zoology for the general public." -S. Harris | henry@zoo.toronto.edu utzoo!henry
shafer@skipper.dfrf.nasa.gov (Mary Shafer) (03/14/91)
From: Mary Shafer <shafer@skipper.dfrf.nasa.gov> John Hall (john@ssd.Kodak.Com) writes: >In article <1991Mar8.021800.7056@cbnews.att.com> jeff@aplcomm.jhuapl.edu (JEFF NANIS ) writes: >| There have been a number of threads concerning the ease with which >|land-based aircraft can operate off of carriers. The following is a letter from >|the back of AW&ST (March 4, 1991) which gives the best explanation I have seen: >| >| "Converting an advanced tactical fighter candidate into a carrier-based A-12 replacement is more complex than suggested... > ... ><many good reasons deleted> >But certainly possible. The land-based BAE Hawk has recently been >modified to be a carrier-based trainer for the USN. Not exactly. That is, no existing BAE Hawks were modified from ground-based to carrier-based aircraft. Rather, the McDonnell T-45 was developed from the BAE Hawk. The T-45 is a carrier-based trainer for the US Navy. No T-45s were ever BAE Hawks. -- 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
arthur@Eng.Sun.COM (Arthur Leung) (03/14/91)
From: arthur@Eng.Sun.COM (Arthur Leung) From igor!yoda!wab@uunet.UU.NET (Bill Baker) > Isn't one of the advanced fighter candidates incorporating thrust >vectoring? It seems like I read this in an article. Wouldn't that >permit much lower sink rates for carrier landings? The main problem >of converting land-based aircraft, historically, has been the airframe >and landing gear relative weakness. that's the YF-22A built by lockheed, boeing, and general dynamics. the vectoring is in pitch only as the vectoring system is based on paddles that deflect into the engine tailpipe. it's not a fully vectorable system as used on the AV-8. this vectoring system is used for high angle of attack operation. according to aviation week, AOA of 60 degrees have been flown with excellent controllability. relatively high rate of roll at high AOA and high pitch response are other gains. >I've always assumed that the >reason the F-4 converted so easily to carrier flight was that it was >built like a tank anyway. well, mcdonnell douglas had a contract with the navy *first* and the air force was told to take it after it was shown to be a pretty hot plane. i believe the air force version retained the navy arresting hook and folding wings. > I would think that, regardless of whether they procure a version >of the ATF, the Navy would insist on thrust vectoring on the next >generation of carrier aircraft. The weight savings from airframe >downgrading could translate into much more range, more room for >weapons and avionics, etc. the distinction between the "thrust vectoring" of the harrier and the "thrust vectoring" of the YF-22 (and the X-31) is fairly clear. you can't get the latter to jump straight up. more, thrust vectoring isn't free. thrust vectoring requires additional equipment - ducts, paddles, hydraulics, pumps, etc. it starts to eat into any gains you might get. dryden has an F/A-18 fitted with thrust vectoring paddles. what is the weight/other penalty for that? any experts on the harrier design? what were the design loads used in the contract specification? (eg: "it has to survive an XXX foot fall on its main gear without damage.") what tradeoffs were made for its jump-jet capability? -- arthur disclaimer: if i knew anything, why would i be reading this newgroup?
jln@leland.stanford.edu (Jared Nedzel) (03/15/91)
From: jln@leland.stanford.edu (Jared Nedzel) In article <1991Mar13.003857.8136@cbnews.att.com> john@ssd.Kodak.Com (John Hall (726-9345)) writes: >From: john@ssd.Kodak.Com (John Hall (726-9345)) >In article <1991Mar8.021800.7056@cbnews.att.com> jeff@aplcomm.jhuapl.edu (JEFF NANIS ) writes: >| "Converting an advanced tactical fighter candidate into a carrier-based A-12 replacement is more complex than suggested... >But certainly possible. The land-based BAE Hawk has recently been >modified to be a carrier-based trainer for the USN. Yes, it is possible. But if you look at the USN Hawk trainer program, you'll see that it has been a major problem. Some of the problems that they've encountered: (from my faulty memory -- check AWST for the details, I may be misremembering some of them) 1) the plane needed a more powerful engine to allow for go-arounds after bolters, 2) to allow for the tail-hook, the air-brake had to be moved; the airbrake now causes a significant pitch input when deployed, which required an airbrake-elevator interconnect, 3) the plane needed new landing gear (of course), which have different aerodynamic qualities, which resulted in unacceptable handling on approach, 4) the plane had unacceptable stall-spin behavior, ..... After all they've gone through trying to get the Hawk to work, you have to wonder whether they would have been better off with a purpose-designed plane. It seems that that's what they're ending up with anyway, after all the mods. to the Hawk :-/ -- Jared L. Nedzel --------------------------------------------------------------------- e-mail: nedzel@cive.stanford.edu jln@portia.stanford.edu
henry@zoo.toronto.edu (Henry Spencer) (03/18/91)
From: henry@zoo.toronto.edu (Henry Spencer) >From: arthur@Eng.Sun.COM (Arthur Leung) >>But certainly possible. The land-based BAE Hawk has recently been >>modified to be a carrier-based trainer for the USN. > >true, but it wasn't without some trial and tribulation. :o) > five major problems - with stability, control, and > engine performance ... Aviation Leak does seem to have a somewhat pro-USAnian anti-foreign slant to its coverage sometimes, and there was at least one relevant fact left out of this piece. The reason for the engine problem -- basically, not enough power -- was that the USN had deliberately asked for a less powerful engine! Well, more precisely, they had decided to use a derated version of the original engine, in hopes that this would give longer life. They have now reversed that decision. This one was the customer's fault. (Not a new problem; the aircraft or its manufacturer often gets blamed for things that were really the customer's mistake.) Most of the other difficulties seem to have been side effects, one way or another, of design changes that were either necessary or at the USN's request. For example, some of the stability problems were the result of the larger nose gear. -- "But this *is* the simplified version | Henry Spencer @ U of Toronto Zoology for the general public." -S. Harris | henry@zoo.toronto.edu utzoo!henry
stevenp@decwrl.pa.dec.com (Steven Philipson) (03/19/91)
From: stevenp@decwrl.pa.dec.com (Steven Philipson) In article <1991Mar13.003648.7991@cbnews.att.com>, igor!yoda!wab@uunet.UU.NET (Bill Baker) writes; > Isn't one of the advanced fighter candidates incorporating thrust > vectoring? Yes. The Lockheed YF-22 employees thrust vectoring nozzles. > [...] Wouldn't that permit much lower sink rates for carrier landings? No -- the nozzles have essentially no effect on approach characteristics. Their main use is in increasing pitch and roll rate and authority. The nozzle design is quite different than the type used on the Harrier. The YF-22 cannot hover or use its nozzle thrust for direct lift. > I've always assumed that the reason the F-4 converted so easily to carrier > flight was that it was built like a tank anyway. You've got that backwards. The F-4 was designed as a carrier aircraft from the outset and later adopted by the Air Force. > I would think that, regardless of whether they procure a version > of the ATF, the Navy would insist on thrust vectoring on the next > generation of carrier aircraft. Why? The Air Force didn't insist on vectoring for the ATF. The Northrop YF-23 doesn't have thrust vectoring and (allegedly) meets the same control specs. The weight savings from airframe > downgrading could translate into much more range, more room for > weapons and avionics, etc. These "savings" don't exist. Note that the Harrier has less range, less speed, and less room for equipment. This doesn't mean that thrust vectoring doesn't have value (it does) and that aircraft such as the Harrier don't have their place (they do). It simply means that vectoring isn't the answer to all problems. > When the time comes to replace the E-2, why not design a new radar > platform with real STOL characteristics? Because those "real STOL characteristics" aren't necessary to get on and off of a carrier, and usually involve penalties in weight and complexity. All "real STOL" aircraft built to date have accepted large tradeoffs in performance (speed and range) to get their STOL performance. These are tradeoffs that are incompatible with the mission of an attack carrier. Steve (the certified flying fanatic) stevenp@decwrl.dec.com