JwcookThe parameters for designing a fighter are surprising similar for any given era…
The technologies are just incremental steps, SFC is a good example where the underlying technology is the same, with better materials more efficiencies can be gained but these are not order of magnitude gains.
Extrapolation from know specifications can give surprisingly accurate results for other systems. (usual caveats apply)
Just for fun – There was a recent report the Raptor does .4mpg depending on conditions and speed (US gallon).
source :- http://www.forbes.com/technology/2008/06/05/mileage-military-vehicles-tech-logistics08-cz_ph_0605fuel.html
just plug in your numbers and see what results (~1000-1200 mile range)
Cheers
JwcookThe F-22’s performance may be affected by continuing increases in aircraft weight, and frequency of required maintenance that is still far from its objective. Even though F-22 aircraft weight is not characterized by the Air Force as a key parameter, aircraft weight impacts several of the key parameters, including supercruise, maneuverability, acceleration, and combat radius. And, even though the Air Force continues to estimate that by the end of the development program the F-22 will meet or exceed its supercruise, maneuverability, acceleration, and combat radius key parameters, the aircraft weight continues to increase as it has since 1995. During 2000, the estimated weight increased because of additional requirements and modifications required to add strength to the airframe. The Air Force maintains that even with this latest weight increase, there is a margin of 1,050 pounds until the aircraft’s weight begins to have an impact on the F-22’s ability to meet its key performance parameters.
source http://www.dau.mil/educdept/mm_dept_resources/reports/F22-development-and-testing-delays.pdf
Bear in mind the since ~2004 there have been 600-800lbs that i know of in additional weight, that only leaves around 200-400lbs weight gain between 2000 and 2004!!, you’ll have to decide if the F-22 remained static over 4 years :rolleyes: Weight always goes up (as it is with all aircraft).
Just make up your own mind if the tiger teams reduced the weight enough.
cheers
JwcookSo, let’s see.
OEW in the “40000lbs class”. We’ll take this literally.
OEW = 40000lbs (includes gun ammo)
NTOW = 66700lbs (from Stevenson’s presentation)
Weapons: 2xAIM9 + 6x AIM120
WW = 2x200lbs + 6x490lbs = 3340lbsFuel = NTOW- OEW – WW = 23360lbs
If we assume 21000lbs as upper limit, we can put the lost 2000lbs on weapons and OEW. In the end, we arrive at a fuel fraction of .315, which is quite good and higher than the claims of .275 (Stevenson’s brief) or the somewhere quoted .29.
yup..
That about covers it.. you can move the figures a round a bit, the empty weight is quite mobile:)
It just needs an accurate figure for any one of the parameters and it will get a lot more precise, there have been some excellent sources posted here, which all point to this general area…and your taking the most optimistic view.
Try the figures with a bit of pessimism in the empty weight department, and ‘bobs your uncle’ thats the ‘sensible’ range from the data available.
Cheers
JwcookWe don’t know what the actual figure is – But we have narrowed it down to more sensible figures..
The range seems to be between 18,400 and 21,000lbs, depending on how much you attach to Empty Weight gains over the last few years and cooling problems in the aft both of which would impact fuel usage.
The takeoff weight is defiantly in the high 60’s, which gives it a lower fuel fraction than first estimated :diablo:
Cheers
JwcookWell does anyone else think the sacking of Air Force Secretary Michael Wynne and the chief of staff, Gen. T. Michael “Buzz” Moseley, is going to impact t he F-22 or even the JSF…
I think it might – Defense Secretary Robert Gates has been critical of the USAF fighting the ‘next’ war and not the current one, the is this the beginning of the end for the F-22 is Gates position hostile see:-http://www.afa.org/magazine/march2008/0308edit.asp
Cheers
JwcookSo the question is:-
Is the briefing that the Norwegians released classified/restricted or for public release or not??.
Cheers
JwcookDoesn’t look like any pylons are attached.
Anyone have any ideas about what is being shown?.
To me the returns are from multiple angles side to side and across the frontal arc not just one direction.
I say this because some of the features would be obscured if it was just from one angle.
But the canards and wings are quite faint even if they are not planform aligned ….
cheers
JwcookBTW theres new Eurofighter documents posted at :http://www.defense-aerospace.com/dae/gauche/sponsors/sponsor_eurofighter/index.htm
Cheers
JwcookA few signs of what .. Presidential ambitions!!! Lol:diablo:
I see Barak Obama in with a good chance of being the next President of the USA, and then theres McCain… does anyone from that part of the world have any feedback on their positions on F-22 and F-35 (I dare I even mention Tankers).
Are they Hawks or doves in the fighter aircraft game?
JwcookWell theres an old saying that comes to mind.
Even a stopped clock is right twice a day!!.
As i said before the opinion may be suspect but is the underlying data sound?.
😉
Cheers
JwcookLol so your saying he’s an anti Carlo Kopp!!.
Like matter and antimatter meeting you should keep these two apart at all costs…
and like Carlo you should be wary of his conclusions, but not dismiss the data behind those conclusions.. I’m sure the answer lies somewhere in between these two opposing views.
The fuel load issue is interesting to me on many levels, the actual fuel level, the secrecy behind it, the false information being put out for it, and the reaction of the two opposing sides when confronted with good source material.
The F-22 is quite a Frankenstein, the production run has had so many changes and mods, some of which were not able to be done to early lots,
Some comments I’ve heard/read are:-
The first 60 aircraft will only be used for training as they are not deployable due to communality problems.
I doubt any of the Raptors I build will be the same.
This points to some interesting compromises inside the jet as the external shape has changed little (ie only a few bulges here and there), but a lot of stuff has been… well stuffed in..
now before everyone jumps up and down – This may be extra fuel tanks to add an extra 2000lbs onto the 18,000lbs, then again it may be other stuff that drops the 21,000lbs figure to 18,000lbs.
If the weight of the aircraft has gone up from 32,000 well into the 40,000lbs class you can bet somethings being squeezed, from an engineering point of view fuel tanks are the easiest to move or resize.
So does anyone have a good reference to the Raptors empty weight or its weight during development/production??.
Cheers
JwcookIts not a question of hook line and sinker, I know the Col has a huge disregard for the F-22, and that should be taken into consideration, as should the USAF vested interest in saying the F-22 is invincible/best thing since sliced bread etc (you wouldn’t want the opposition thinking they had even a small chance).
But you have to give the Col some credit having got so far up the chain of command not to use figures which are false, this is the quickest way in which to lose credibility for your arguement.
By all means take what he’ saying with a grain of salt, but do the same to the counter arguments.
See KKM57P post re James P. Stevenson, that makes interesting reading.
The weight of the F-22 has gone up and up, but the figures used never change!!, its not a 32,000lbs class aircraft any more…;-). the fuel load hasn’t been shown to have decreased even though 600+lbs of new equipment/alterations have been stuffed into a crammed airframe.
Cheers
Cheers
JwcookI have seen a quote that the YF-22 had 25,00lbs of fuel… source Dr David barker in the Air international suppliment states the YF-22 had 11,3040kg (25,000lbs) of internal fuel.
More interesting tidbits:- the estimates of key parameters for the F-22 say the Combat radius is at 115% of estimates.. if you can assume the fuel load is the enabler in this then take 18,000lbs and increase that by 15% you get 20700lbs seems these figures keep coming back!!.
Col Everest Riccioni a noted F-22 opponent stated in 2000 the F-22 had a fuel load of 18,500 – 18,750lbs and it weighed in at 65,000lbs (at take off) giving a fuel fraction of 29%
Note:- The F-22 fuel fraction is given as 30% and the Typhoons fuel fraction is 31% – source page 6 Norweigan Typhoon offer
Note:- fuel fraction is weight of fuel divided by aircraft weight at takeoff.
So is the F-22 65,000lbs or 66,000lbs or what at takeoff?
JwcookSpot on ELP re the safety write-up.
OK a quick round up…
18,00lbs is the ‘official’ figure, which seems too low form an engineering perspective, the original goal was 25,000 thats taken quite huge hit.
18,448lbs seems to be mixed with the JSF internal fuel figure despite the ppt presentation of Mike Wosje, it would be a huge coincidence for then to be the same.
20,469lbs Is on an older Technical Order rev 11 with dodgey conversion factors, this weakens it claim a lot but by no means excludes it.
xx,xxxlbs is on the current Technical orders, but apparently isn’t 18,000lbs, possibly the same as the older one and has been stated as wrong by the US Air Combat Command..
and then theres the real figure…. which could be anything from 18,000 to 23,000lbs, or any one of the above.
It will be interesting to see if the TO is changed as you suggested or if the official figure is raised/disappears…
Or odder still if they remain different and a variety of excuses are released as to why they differ.
JwcookI find it difficult to believe that the residual fuel would amount to ~2000lbs I would err on the side of a couple of hundred pounds of fuel in a combat aircraft, it would be madness to put a ton of dead weight into a fighter..
I have no doubt the F-22 has secrets, I just want a definitive figure for the public on internal fuel load, which one do you think it is? and why?
The public figures are now pointing at 18,000lbs but this figure of 20,649 keeps coming back, I think mainly because of the old Tech Orders!!.
Cheers
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