Abraham Gubler said:I think you're being unfair to Ricionni about the F-22, he wrote the ATF specification so he's hardly an anti F-22 person.
I'd be interested in reading your source of that information.
Abraham Gubler said:I think you're being unfair to Ricionni about the F-22, he wrote the ATF specification so he's hardly an anti F-22 person.
The seminal work on supercruise was done by Col. Everest Riccioni USAF
Ret. at the Northrop Corporation during the early years of the ATF
competition. He determined that fuel fraction was a critical factor in
obtaining range for a supercrusing aircraft. At the time of the ATF
competition, the range goal for the ATF was to cruise sub-sonically for
100 miles, then in 400 miles in supercruise, back out in supercruise,
and home 100 miles subsonically.
The F-22 has breached the Riccioni ideal of 0.38 as well as the minimum
acceptable fuel fraction of 0.35 due to increasing weight. Indeed, the
Air Force admits to a fuel fraction of 0.29, a figure that is bettered
by other aircraft including the F-15C, the aircraft the F-22 was
designed to replace. The F-22 does not have the fuel fraction of, for
that matter, the F8H a Navy jet that first flew in the mid-1950s.
Riccioni estimates that the F-22 at its current fuel fraction has a
supercruise range between 90-125 miles.
Woody said:As to rediculous procurement overspends, performance shortfalls and missed delivery dates, we all know this would be called coruption or at least incompetence in the real comercical world. If you want a prime example just look at the the Nimrod MRA4. An ungrade to an existing aircraft of 1950s design started in 1992 and still nowhere near completion. It's not just the American system that's in trouble.
sferrin said:Okay that's just the supercruise portion not the entire specification of which supercruise is but a part. And it doesn't sound like he wrote it but more like came up with "here is one way it can be achieved". The USAF writes the spec. companies have to meet. And if he worked for Northrop that could account for some of his bias. In the end though the USAF is more than happy with the F-22 so Riccioni and Sprey come across sounding like a case of sour grapes.
Abraham Gubler said:sferrin said:Okay that's just the supercruise portion not the entire specification of which supercruise is but a part. And it doesn't sound like he wrote it but more like came up with "here is one way it can be achieved". The USAF writes the spec. companies have to meet. And if he worked for Northrop that could account for some of his bias. In the end though the USAF is more than happy with the F-22 so Riccioni and Sprey come across sounding like a case of sour grapes.
I think you really need to understand more about the ATF program and its history to be making those kind of calls. The basic specification for the ATF was written in then 1970s outlining what USAF wanted it to be. As to the USAF being happy with the F-22, don’t believe the hype... You can learn some more:
http://pogowatercooler.org/m/dp/dp-fa22-Riccioni-03082005.pdf
sferrin said:POGO and Riccioni are NOT the USAF.
sferrin said:As for the ATF requirement *as it existed when RFPs were released* it had changed significantly from what was being toyed with in the 70's. I'd recommend the book "Advanced Tactical Fighter to F-22 Raptor: Origins of the 21st Century Air Dominance Fighter" and Jay Miller's book on the F-22. As for Ricionni and POGO's opinions I won't comment on them for Paul's sake.Suffice it to say about all they're lacking are the torches and pitchforks.
sferrin said:"Raptor Rocks
Airspacemag Aug-Sept 2006
For their performance, which started at 2:40 p.m., Shower and Bergeson took off from Langley, 800 miles away, at about 1:25. "We were going slow," Shower says. "We were only doing about .9 Mach. Over the continental United States, there’s only a couple of places we’re allowed to go supersonic so we don’t scare everybody. But we did the math and figured we could be there if we supercruised in about 25 or 30 minutes. "
lantinian said:May not sound like much but how good will the F-15C do in the same
circumstances? It has less internal fuel and twice the SCF to keep the same speed![]()
May not sound like much but how good will the F-15C do in the same
circumstances? It has less internal fuel and twice the SCF to keep the same speed
Yeah but no one would ever fly the F-15C on an all supersonic profile, it would cruise at transonic and accelerate to supersonic for missile launch, positioning and evasion.
lantinian said:So, the hell with these fuel fractions and Col Ricconi. The truth is that when comparing just Range/Speed performance, the F-22 is a superior aircraft.
Abraham Gubler said:lantinian said:So, the hell with these fuel fractions and Col Ricconi. The truth is that when comparing just Range/Speed performance, the F-22 is a superior aircraft.
Yeah of course it is. But considering that this differential in range/speed is much lower than originally programmed is the F-22 improvements worth spending $70 billion on for just 180 airframes? For that money USAF could have brought over 700 brand new Super Hornets... or 70 more B-2 bombers? 70 extra B-2s all in service by 2005 if USAF had canceled F-22 in 1997? Both would be far more useful than the F-22...
lantinian said:0,664 pounds of fuel per pounds of trust per hour, at 2x21,500 lb of trust from 14,400 lb of available fuel will allow the two Raptor
engines to run for roughly 30 minutes total.
lantinian said:0,664 pounds of fuel per pounds of trust per hour, at 2x21,500 lb of
trust from 14,400 lb of available fuel will allow the two Raptor
Where do you get the 14,400 lbs of fuel from? According to Technical Order 00-105E-9 Segment 12 it's ~20,700lbs of internal fuel (3082 gallons). (Yeah, I've seen the 18,500 figure too but don't know the original source of that.)
As I explained in my post, I believe the F-22 is on about 82% throttle setting when doing Mach 1,5 at 40,000 feet. SFC is bond to be at most 88% from the full dry setting of 0,8 lbm/lbf/ht, hence 0,664.0.664 lbm/lbf/hr seems like a rather low value for the F119 SFC cruise, just based on comparison with other engines.
sferrin said:Not in 2020 when both PAK-FA and J-XX are in service, the F-15s are falling out of the sky and so forth. If anything we should buy MORE F-22s so the investment doesn't go to waste. Better to get the required number now than to cancel it and discover in 15 years we need more and have to fund an entirely new program at even more money. Short-sightedness seems to be the national pass time these days.
sferrin said:lantinian said:0,664 pounds of fuel per pounds of trust per hour, at 2x21,500 lb of
trust from 14,400 lb of available fuel will allow the two Raptor
Where do you get the 14,400 lbs of fuel from? According to Technical Order 00-105E-9 Segment 12 it's ~20,700lbs of internal fuel (3082 gallons). ??? (Yeah, I've seen the 18,500 figure too but don't know the original source of that.)
The F-35s will more than deal with the PAK-FA/J-XX.
The 18,500 lbs figure is from USAF. While the fire fighting TOs say 20,700 lbs they are wrong. Most likely because a fuel tank has been deactivated
Abraham Gubler said:sferrin said:Not in 2020 when both PAK-FA and J-XX are in service, the F-15s are falling out of the sky and so forth. If anything we should buy MORE F-22s so the investment doesn't go to waste. Better to get the required number now than to cancel it and discover in 15 years we need more and have to fund an entirely new program at even more money. Short-sightedness seems to be the national pass time these days.
The F-35s will more than deal with the PAK-FA/J-XX.
Abraham Gubler said:The 18,500 lbs figure is from USAF.
Abraham Gubler said:While the fire fighting TOs say 20,700 lbs they are wrong. Most likely because a fuel tank has been deactivated - its there in the aircraft but you can't fill it with fuel but the fire fighters take note of it anyway.
There is at least one very respected author/engineer who will very much disagree with you. His name is Dr. Carlo Kopp and he's got plenty of analysis of the case for/against F-35 to justify his point of view.
sferrin said:What source do you have that is better than a TO?
Abraham Gubler said:sferrin said:What source do you have that is better than a TO?
USAF's offical statements and those from Lockheed to Congress... There are many different types of technical orders. That people like APA cling to a TO for firefighters as the basis of their capability analysis of the F-22 is not a good idea. If the F-22 could carry 20,000 lbs of fuel it would have better range than it does now.
sferrin said:I'd be interested in the relevant cites.
Fuel Capacity: Internal: 18,000 pounds (8,200 kilograms); with 2 external wing fuel tanks: 26,000 pounds (11,900 kilograms)
Combat Radius (NM) Mission 1 (Sub+Super) 310+100nm
Had to fix this one. I added the red part. The graphic is an approximation, but much closer to the aircraft's real envelope.
sferrin said:Is there a reason you need to be an ass about it? Is there something wrong with asking for your sources?
Abraham Gubler said:sferrin said:Is there a reason you need to be an ass about it? Is there something wrong with asking for your sources?
Don't think its an attack targeted at you. This issue (F-22s vs the World) has been so heavily coloured by misrepresentation it has actually become so ridiculous I thought a nice post summing up some of the best craziness would be appropriate.
flateric said:Four tanks question was discussed with one of raptor drivers at f-16.net forum - was reading this recently. F-22 has the ability, but will never fly with four tanks in his words.
flateric said:believe me, he's the one *in a position*
lantinian said:As I explained in my post, I believe the F-22 is on about 82% throttle setting when doing Mach 1,5 at 40,000 feet. SFC is bond to be at most 88% from the full dry setting of 0,8 lbm/lbf/ht, hence 0,664.