Question on throttle control
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I have a CH Throttle and have calibrated it.
I have the afterburner mark as close to the top as possible so that the very last movement goes into afterburner.When I move the throttle just below the afterburner mark, the fuel flow goes from 0 to about 14,000 lbs which allows me to cruise at about 300 knots. If I want to go to about 400 knots at level flight, I have to kick in the in afterburner. Once I hit the 400 knots I move the throttle back to just below the afterburner mark, and my airspeed drops.
PS - yes -I make sure that my airbrakes are closed
Shouldn’t the fuel flow move to higher amounts before the afterburner set in? (ie. 20,000, 25000 lbs or so before it kicks in) It is like driving car and if you push the pedal down 9/10th of the way, you can only go 20 miles an hour and you engine is running at about 30% capacity, but if you push the pedal all the way, then next level is the engine is revving at 100% and you go 250 miles an hour.
Is this the way it is in Falcon BMS?
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Fuel flow numbers make sense to me. Keep in mind that afterburner bring something like 30% more thrust, but burn 3 to 4 more fuel.
As for the cruise speeds you are mentionning, is it CAS or TAS ? Default HUD setting is CAS. 400 kts CAS at 20000 feet brings you close to Mach 1, and you cannot be supersonic without afterburner in an F-16. So I’d say all of what you are describing is normal.
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What’s the main reason why a clean F-16 can’t supercruise? Why is the drag too high to supercruise? Because e.g. the much older English Electric Lightning was the first fighter capable of supercruise.
Aren’t the wings swept back enough; because the original “light weight fighter” was built for turning fights instead of high speed intercepts?
But why didn’t they further reduce the wing loading then in the original design, like they did (or would do) in the F-16 XL? -
Because the transition from subsonic to supersonic takes 3-4x’s the energy just to make the transition into supersonic flight. Drag increases exponentially at that speed, so the thrust required is exponential to make the jump…can’t remember exactly, but has something to do with the aerodynamics at transition that requires much more energy to break through…it’s been awhile since my physics classes in college.
I’m sure somebody will expound on this topic.
Good day!
DrDetroit
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Main reason is that big fat engine intake. The testbed for the F-35s EGI was an F-16, and with that intake on it, the F-16 can supercruise.
as mentioned, drag increases in the transsonic region from roughly 0.8 to 1.2 mach. total Drag decreases above 1.2 mach.
Some aircraft which are borderline can do a dive to get supersonic, then accelerate once above the mach, as the engine thrust without the extra drag is enough to keep them supersonic. The F-16 as produced is not one of those aircraft.
The English Electric Lightning also had the benefit of two engines, and the corresponding fuel burn to go with it. Its all tradeoffs.
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Because there are no M1 speed limits it is simply a case of not enough military thrust to overcome the drag.
If you go through in burner initially some F-16s might have been able to do this in some conditions:
Back in 1980 we could stay at 1.1M or so in mil power at 40K. This was with 'winders on wingtips and maybe a centerline tank. On a cold day, we could get supersonic at 20-25K in a shallow dive without using burner. This was with stock F100 motors, small mouth Block 5 and 10 beasts.
http://www.f-16.net/forum/viewtopic.php?f=23&t=8643&sid=a0af2afd1595603c0911be2471f8654a&start=15
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Aren’t the wings swept back enough; because the original “light weight fighter” was built for turning fights instead of high speed intercepts?
But why didn’t they further reduce the wing loading then in the original design, like they did (or would do) in the F-16 XL?The wing was a compromise to allow both good speed and turn performance - and they didn’t need to reduce the wing loading.
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If you go through in burner initially some F-16s might have been able to do this in some conditions:
Back in 1980 we could stay at 1.1M or so in mil power at 40K. This was with 'winders on wingtips and maybe a centerline tank. On a cold day, we could get supersonic at 20-25K in a shallow dive without using burner. This was with stock F100 motors, small mouth Block 5 and 10 beasts.
http://www.f-16.net/forum/viewtopic.php?f=23&t=8643&sid=a0af2afd1595603c0911be2471f8654a&start=15
That is a cool find there. Sorta lends credence to the (anecdotal) stuff about the big intake on the later blocks being the root cause…
Gums has some interesting posts on there…
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That is a cool find there. Sorta lends credence to the (anecdotal) stuff about the big intake on the later blocks being the root cause…
Gums has some interesting posts on there…
To right.
Okay so in theory the Block 52 which has the same small inlet as the Block 5/10 would have similar drag (maybe a bit more due to weight/ AOA) but about 3000 lbs more SL Mil thrust - so would be the best candidate for supercruise.
However looking at the BMS HFFM thrust charts - the Mil thrust on the PW-229 dips around M0.8 (stagnation pressure loss?).
So at M1.0 / 20,000ft for example the PW-229 and PW-200 and PW-220 all show an output of around 8000 lbs thrust.
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I just tried a clean viper in BMS, block 52 and it can’t. Neither the C nor the D, not in 30K, not in 40K.
I think it’ll do when the fuel is used up. I had Mach 0.95- 0.98, so it’s pretty close. Fuel state was about 6000lbs. It will slow down from Mach 1.1 to just below Mach 1.
Maybe it’s the weather too…
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Had a burn yesterday (2 x AIM-120) - same results on the M1.1 slowdown at 40K
A colder temperature could be the trick here - just enough thrust increase to maintain the M1.1.
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Does it get much colder at 40k?
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Around -58F or -50C
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Looking at the speed chart the best MIL speed is around 20,000ft - 25,000K ft.
I can sustain M1.00 clean / level with the D B52 at ~21700 ft if that qualifies
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Should be able to get faster again on the C blk 52, then.
Speed chart? -1-1 by any chance?
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Yes the chart is the C B52 from the -1-1
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