SchorschEdit: The only serious way to compare fuel between fighters of different sizes is to look at fuel fractions.
Correct, with some limitations: comparing early turbo-jet equipped jets versus 4th generation aircraft may be misleading, for subsonic range newer jets usually make more of the same fuel fraction, the F-22 is another beast, again. But roughly, fuel fraction gives an indication (for clean aircraft).
Schorschwhat do you mean by “allowed airspeed”? Actual restrictions placed by the producer on the plane, or by conditions?
cheers
An aircraft has a maximum dynamic pressure limit, or VMO (V Max Operating).
That is for load and flutter considerations.
A fighter aircraft or low level bomber normally has 700 to 800 Knots (EAS, that is, actually a bit more in real due to compressibility). Aircraft like the B-58 have lower KEAS (Knots Equivalent Airspeed), it actually is not allowed more than M0.8ish at low level. Same would apply to Mirage IV or Tu-22.
Probably so the canopy doesn’t melt.
Such restrictions make the maximum Mach number.
So were the other aircraft (Mirage IV, TSR.2, B-58) better suited for high altitude, supersonic cruise than the F-111?
A decent read at Wikipedia would answer most of your questions. The B-58 for instance was designed to fly supersonic at altitude.
Additionally, all other were turbojet equipped with advantage in supersonic speed, but preposterous fuel burn low and subsonic (see Suchoi 24).
The F-111 got pretty high bypass turbofans and therefore suffered in afterburner. Add to that the high static margin and the less than perfect aft-body design, and you’ll get an aircraft that doesn’t feel home in supersonic.
As hint: green painted aircraft tend to fly low!
SchorschFirst off, the F-14 never got AMRAAM capability.
Secondly, there were various fleet air defense loadouts. One of them was four AIM-54s, two AIM-7s, and two AIM-9s. That was pretty common for a full-up load from a carrier.
I’m not sure they ever used the four AIM-9 option all that much.
For air to ground work the Tomcat could carry dumb bombs on the four Phoenix stations under the fuselage. Recently they have carried LGBs on the foward two stations, with two AIM-9s, one AIM-54, and one targeting pod underwing. That’d be a common A/G loadout towards the end of the Tomcat’s career.
MiG-27 had two wing glove stations, one centerline, two forward underfuselage stations, and two stub pylons aft of those where I’ve seen smaller bombs being carried.
Thanks.
I read in Wikipedia that 2SR/3MR/2LR was a typical F-14s load-out.
The 4 Phoenix carrier was more limited in performance and Phoenix (4 means close to 2t of weight) missiles were not all that plenty.
As for the MiG-27, maybe someone has a “typical” strike config and an indication which weapons were used (500,1000,2000lbs).
I would think that it goes with one external fuel tank on centerline, and one 500lbs buster on each pylon (total of six).
Does the MiG-27/23BN has anything like multiple bomb racks?
SchorschAs was the F-104, until the G variant arrived and that wasn’t brilliant tbh.
Sorry, more than 2000 built?
The F-104G could strike the WP-airspace with near impunity and had better electronics than most Soviet strategic bombers. That nasty beast could deliver a B28 with very little chance of being intercepted, that with a 300+nm radius in lo-lo-lo.
SchorschSchorsch
Actually it was the exact oposite.
When the Lightning´s sqn´s in Gemany got to receive the Phantom, it was a disappointment, a lot of pilots were very vocal about what they feel was a “backward step”.More often than not, in exercises, the Spey equiped Phantom´s got on the wrong end of high speed slashing attacks coming from above, and when trying to engage the Lightning´s they would be left behind in a zoom climb.
These tactics were only countered on an efective way when the BAE Sky Flash got to perform has it should.And i would dare to say that these vertical “slashing attacks” would be quite efective against any Mig, at any altitude.
Of course, smart pilots will use the available performance of their aircraft to full advantage. Any European conflict would have taken place at low to medium level for most of the time. There the Phantom has some serious advantages:
– two pilots (anything above 2 vs 2 this can be the decisive factor in visual range, no matter how much thrust or how low the wing loading)
– better performance below Mach 1
– more weapons
A “slashing” attack is very effective, but requires some prerequisites: primarily an early detection (which the Lightning can’t do on its own) and initiative.
Actually, that would make a very interesting “A vs B” thread, using an actually trained encounter, with dissimilar aircraft, strictly late 1960s and early 1970s weapons (rear quarter SR and miserable MR). Someone interested?
SchorschWhich could fly the fastest at sea level, the Tornado IDS of F-111?
I have heard mach 1.3 clean for the IDS :confused:
The sea level top speed normally is governed by allowed airspeed.
It is not about drag or engine, at least most of the time.
SchorschSo basically as long as it didn’t play into the Lightning’s strengths, which is why the Lightning lived on until 1988. The spey-Phantom retired a year later. Considering the latter was ten years younger it seems odd that they both had nearly identical departures, that is unless they both had similar shortcomings.
The F-102 retired in the early 80s, actually after some more advanced design elsewhere in the world. Was it so advanced?
No. The Lightning did the job well it was supposed to do: catching high flying intruders, which are identified by ground radar. Aircraft is vectored in, fires both missiles, and gets back to base before fuel is out. Interceptor.
For fighter duties it was totally inadequate, lacking maneuverability, range, weapons load, requiring long runways, and being quite a large target after all. Any MiG-21 or Mirage III could do a better job.
So they were sold by the hundreds.
If a Lightning would try to win air superiority the 1960ies way versus MiG-17 and MiG-21, it would fail. Against MiG-23 there is no hope either.
SchorschIs the F-111 capable of cruising at supersonic speeds?
No.
The F-111 has a very high static margin and experiences high trim drag at supersonic speeds.
Flying supersonic with the F-111 is a fuel disaster.
It was originally designed to make a several hundred nautical mile dash at M1.2 and sea level towards the target, but this requirement was more or less canceled, as the fuel expenditure was preposterous.
For the intended mission (dropping a single B61) it was a good aircraft and could go low level at relatively high speeds (M.8-.9) for long distances at any weather.
SchorschConceptually flawed? Purely psychobabble talk! The Lightning rocked.
An aircraft designed to intercept Soviet high altitude bombers 200nm off the shore of Her Majesties Kingdom.
The Soviets never had such bombers. Fighting nimble MiG-21 in the expected low- to mid level fur-ball over Western Germany, there was hardly any aircraft less suitable for it than the Lightning.
As I said, a technically very good design, very good engines, but conceptually flawed.
At the same time, after the Hunter went to the scrapyard, the RAF never had a really useful fighter (I guess the F-4 was OK) before the Eurofighter came.
I’d say potentially, but flawed in practice. Conceptually brilliant: a Phantom with better take-off performance (carrier pilots loved that!), better fuel economy, better low-level speed, better climb rate & acceleration. But production was too small to spread the development cost out, making unit price far too high, & the fatter rear fuselage imposed a drag penalty.
Unfortunately UK bought the Phantom “too early”, they couldn’t take full advantage of the improvements made in the E and F model (gun, slats). A Spey’ed Phantom with slats and cannon would have been a very strong contender in the visual and beyond-visual arena, in the expected European theatre.
Would eat a Lightning any day and time fur lunch, except if it was at 45000ft.
SchorschMy heart says the Brits should have evolved the lightning rather than putting speys into phantoms…
My mind says they should never have produced the Lightning in the first place.
A conceptually (not technically!) flawed design.
The Spey Phantom was a winner though.
SchorschFifth,They will also need to climb to, say 40.000 ft.
It could be productive to discuss these matters, and how they affect time, especially when compared.
The burn rate is well documented at full thrust however, so its a good start.
[doesn’t give you much]Lets take a look at your first point, –
do the aircraft cruise with full thrust ?I’d say NO, cruise is usually reffered to as the most fuel efficient speed, some Mach 0.7
But then again i said “at full dry thrust”, meaning max dry thrust, so that makes your first point irrelevant in max dry thrust comparison.
[it doesn’t, understand “partial power performance”]Second, do engines actually produce the advertised thrust at cruise speed and altitude?
According to this sheet http://www.tailhook.org/RENO%202007%20BRIEFS/Friday%20Briefs/RaptorBrief.ppt
It produces the advertised 55.000 thrust at all altitudes, tho you dont get the same speed at all altitudes. I’ll assume the same goes for both engines.
[have you ever heard the term “atmosphere”?]Third, do engines have anything like the advertised zero alt zero Mach uninstalled SFC at cruise conditions?
Not sure about this: would you mind give an estimate ? more specifically if there is any notable difference ?
[yes, there is]Fourth, do the engines run with full power at cruise?
Same question as first, and same answer, irrelevant. -unless you mean supercruise ?
If that was the question, then it seem logical that full power =max thrust.Fifth,They will also need to climb to, say 40.000 ft.
True, and for once something that obviously differ between the two, i’ve been told F-22 weighs close to 3 times more and would thus require close to 3 times more fuel.
[that is at least a somehow valid assumption]This is quite an interesting comparison i’d say 🙂
First, for very basic starters, thrust declines with altitude.
Optimum cruise Mach number is .8-.85 for both aircraft (a2a).
For starters:
http://www.aircraftenginedesign.com/pictures/fig_14c.jpg
SchorschAs F-22 Raptor is the benchmark as far as supercruise goes, I’ll add this rough time estimation at full dry thrust for comparison. Later info indicate a higher fuel burn for both of them, which would favor a smaller engine.
F22 Internal Fuel ~18448 lbs
(2 x F119)
55000 lbs Mil thrust @ 0.7 lb/lb.hr~0.48~29 minGRIPEN NG Internal fuel ~7100 lbs
(1xF414)
~15000 lbs Mil thrust @ 0,7 lb/lb.hr~0.68~41 minSummary:~Gripen NG +41% increase in time over F-22 Raptor.
Perhaps we should have a discussion as to what minute supercruise suddenly become operationally useful ? 🙂
Maybe we should have discussion about your ability to handle numbers.
First, do aircraft cruise with 100% installed thrust?
Second, do engines actually produce the advertised thrust at cruise speed and altitude?
Third, do engines have anything like the advertised zero alt zero Mach uninstalled SFC at cruise conditions?
Fourth, do the engines run with full power at cruise?
Hint: the answer to all questions is NO and your calculation totally flawed.
Advise: do not use SFC if you don’t understand it.
SchorschOh, I wouldn’t say that! If, any aircraft could maintain Mach 1.2 for a extended period that would be very valuable. Especially, if it could do so with a respectable weapons load………:D
No, it would lose quite a lot of range for a rather neglectable speed increase.
It makes more sense to go all the way to M1.6 and use the A/B.
Read this thread and understand!
Can´t make that assumption… the gripen C/D did it with much less thust and AoA ordinance(ok only at right above but any way).. And it does not stand anything about the max dry speed.. normaly envelope expands..so its maybe not full or even military dry thust..
also the fuelfraction of 0.31 makes it a good ranger..
I can.
Just more thrust doesn’t help for real “supercruise”.
Fuel fraction is nice but only counts in subsonic for comparable mission profile.
Any average 4th generation fighter will see from M0.9 to M1.2 a 100% increase in drag coefficient, a 10% increase in SFC and a 60% increase in dynamic pressure, resulting in:
SR = V_TAS/FF
FF = CD * qdynS * SFC
SR1 = 1
SR2 = 1.3*V_TAS / (2 * CD * 1.6 * qdynS * 1.1 * SFC)
SR2 = .37 * SR1
30% faster for a 63% loss in specific range. Bad trade.
Note that I used rather conservative numbers.
Schorsch2009-01-21 | During last Autumn, the Gripen Demo performed 40 sorties as part of the development programme that focuses on opening up the flight envelope regarding speed, altitude, angle-of-attack and loads. This year, the testing has continued at the same high tempo. Today’s supercruise flight is part of the ongoing high speed supersonic testing that will include supersonic flights, with different load alternatives.
Saab test pilot Magnus Ljungdahl flew the Gripen Demonstrator aircraft in supercruise.
“The flight was conducted over the Baltic Sea, my altitude was 28, 000 feet and the speed achieved was above Mach 1.2. Without using afterburner I maintained the same speed until I ran out of test area and had to head back to the Saab Test Flight Centre in Linköping.”
Although an achievement the ability to maintain M1.2 will not yield a big advantage in operation. Any “supercruise” under M1.3+ is of limited use because of the miserable relation between added speed over ground and loss in specific range.
SchorschWrong.
I believe Boeing (or was it NG?:)) ended up with the design…and the tooling, I believe, still exists.
With the tooling existant, and without any real high-tech components or special parts like a titanium wing box
(I once had a Fairchild tech rep say to me…only half joking…he thought there may have been F-84 parts lurking in there…and he wouldn’t bet against finding some Thunderbolt pieces as well), you could set up an assembly line just about anywhere.
Or outsource it to Korea.
Wait.
They done that already.
My bad.
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