HP requirements for super sonic

[dicer]

Yes not thrust. Approximate HP required for old planes like the F104 star fighter and F16 to maintain super sonic speeds?
And curious about the difference of drag coefficients between the two.

 

[IRstuff]

Is HP even relevant? Most planes of that era used after burners to get the thrust required, but the thrust didn't come from the turbine, per se.

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[GregLocock]

power=thrust*velocity, in the correct units

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[tbuelna]

It is not fair to compare performance of the F104 to the F16. The aircraft were designed for different missions at different times. The F104 obviously did not have the benefit of technology that the newer F-16 did. If you have detailed performance data for both aircraft at similar conditions, you should be able to work out the HP required to maintain a mach 1+ speed. The biggest difference would be efficiency of the engines.

Consider that the F-22 can fly at mach 1+ (supercruise) without using afterburners, which makes a huge difference in fuel consumption.

 

[GregLocock]

As an example I back calculated the fuel consumption of a B-58 Hustler, it varies less than you might think over the range M1.2 to M2.0


Speed Fuel consumption lb/nm
Cruise 18
M1.2 44
M1.6 45
M2.0 52

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[KENAT]

Concorde also flew at 'super cruise' as I recall somewhat faster than F-22;-)

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[GregLocock]

Concorde flew more supersonic hours than all other aircraft combined to date, according to an unimpeachable source.

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[KENAT]

More impressive at least under some conditions an English Electric Lightning was also capable of supercruise.

Of course rang is so short that use of the term 'cruise' is debatable;-).

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[GregLocock]

According to the unimpeachable source (wiki) any plane that can fly at M2 will probably be able to supercruise, that is, the claim is that the v^2 effect is so great it dominates the roll off of Cd in the transonic region and the thrust augmentation from reheat (afterburner) is only likely to be a factor of 2-4.

It's a neat rule of thumb, immediately contradicted by the Hustler's example.

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[tbuelna]

The Olympus engines on the Concorde only produced about 8% of their thrust from the engine core during cruise at mach 1.5+. Most of the rest of the thrust came from the variable intake duct flows and exhaust reheat. The F-119 engines used on the F-22 operate at mach 1.5+ as true turbofans. This is far different than the Concorde's Olympus engines.

 

[KENAT]

I didn't think Concorde uses reheat/after burner at normal cruise speed.

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[berkshire]

It did not .
The Concorde used re heat to get up to Mach 2 then used just the turbojets to maintain that speed.
B.E.

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[KENAT]

That was my understanding berkshire - and not just from Wikipedia.;-)

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[berkshire]

Yes here is an anecdotal story about that engine.
It was an extremely powerful engine, before I came to the states I was at Bristol, the day an Avro Vulcan used as a flying test bed with one of those engines mounted centerline under the fuselage, got too far down the runway on an approach into Filton airport, and firewalled everything he had including the Olympus .
There was a petrol station ( Gas Station ) on a road at the end of the approach to the runway. The whole thing was blown flat, pumps, buildings, everything The official line was that the aircraft was being delivered, he had the engine fitted and running.


Here is an except from an official report : On 16 September 1960, Vulcan B.2 XH557 wrecked the appropriately named "Runway Garage" at Filton. XH557 had been allocated to Bristol Siddeley Engines to test the Olympus 301 engine and was being delivered to Filton. Approaching in poor weather conditions, the aircraft touched down halfway along the runway. The braking parachute was streamed but realising the aircraft would not stop in time, the captain opened the throttles to go round. A street light on the A38 was struck as the aircraft climbed away, leaving a scene of chaos behind it. The Runway Garage took the full force of the jet blast: four petrol pumps were blown flat; a street light lay across the road; railings were blown over; and cars had their windscreens shattered. The aircraft diverted to St. Mawgan and was flown back to Filton some days later.[210]

B.E.

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[GregLocock]

Slight nerdy additional detail, Concorde could accelerate all the way to supercruise without using afterburner, but it was more fuel efficient to get through the transonic hump in drag by using it.

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[tbuelna]

The Concorde used afterburning with the Olympus engines to accelerate to mach 1.5+ speeds. But when cruising at that speed most of the thrust was produced by intake flows diverted around the engine core.

From an "impeachable" source: "During the Supersonic cruise only 8% of the power is derived by the engine with the other 29% being from Nozzles and an impressive 63% from the intakes."

 

[KENAT]

tbuelna, weren't arguing the significance of the inlet & nozzle design making the turbojet act as a pseudo ram jet at cruising speed. Point was afterburner wasn't used to maintain supersonic speed - hence super cruise.

As I recall the SR-71 engine intake & nozzles worked similarly.

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