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View Full Version : Planes Don't Bleed Energy in Turn?



VF2_Tim
11-15-2004, 10:27 PM
Two planes meet head to head. both at full throttle. One keeps a straight line and blows straight through. Other plane makes max G 180 and falls in behind the other plane for a shot?

A max G turn should totally kill the turning planes speed. Or, if the turning plane did a low load wide turn, by the time they got turned around 180, the straight flight plane would be parked outside the officer's club at his home base AND be on his second beer.

I'm no flight engineer and, admittedly, I'm not a very good pilot either but it seems to me that these planes aren't bleeding energy in a turn like they should.

Before I get a flood of 'depends on the plane and the situation' replies, I'm speaking generally. Shouldn't almost any fighter that holds a course at top speed outstrip another fighter that it just passed in level flight going the other way?

heywooood
11-15-2004, 11:25 PM
Planes will fly a turn you know...if you do it right, you can bend a 180 without much bleed...

now if you see alot of wingtip vortices then there will be significant energy loss, but a smooth, high energy turn is possible...in fact, it is a required skill.

I am sure there is a track of a good, high energy 180 out there somewhere..

NimbusPlus
11-15-2004, 11:54 PM
The thing is "a max g turn". So we have a max g turn, level flight (maintain altitude), full throttle. As I see it, since you're pulling a lot of g's, that means the a/c is weighting a lot. That means that, since you maintain level flight, the wings are creating a lot of lift (to compensate the weight). A lot of lift means a lot of (induced) drag. In the end, you're getting a lot of drag, so I would say yes, your airspeed is going to decrease pretty fast.

Another detail is that if you want to make a turn to fall excatly in line behind the first a/c, you're not making a 180-degree turn (which would have you ending up flying a course parallel to the preceding a/c; quite spaced because of the high speed=>high turn radius). You're actually making a full 360-degree turn: a 270 followed by a 90-degrees turn to fall back behind the first a/c); so the trailing one would be even farther away.

Tully__
11-16-2004, 02:25 AM
Was it a level turn? If not, it's possible to turn quite tightly without losing nearly as much energy.

Was it a computer controlled plane? If so, they cheat. The flight model used by the computer uses some short cuts not available to human pilots.

Aero_Shodanjo
11-16-2004, 08:18 AM
Slightly off topic perhaps, but in that particular case, how about doing a vertical loop and continue with a roll to get behind and above the other plane that's flying straight?

The chasing plane will have an altitude advantage and can dive to regain his speed again, right?

NimbusPlus
11-16-2004, 11:02 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Aero_Shodanjo:
Slightly off topic perhaps, but in that particular case, how about doing a vertical loop and continue with a roll to get behind and above the other plane that's flying straight?

The chasing plane will have an altitude advantage and can dive to regain his speed again, right? <HR></BLOCKQUOTE>

Right, but it will also have lost some speed during the first part of the loop. I don't know; I think it's hard to compare those two scenarios at first glance.

It might also depends on the type of a/c. Maybe one with a powerful engine (lot of power available) would have an advantage in doing the vertical maneuver instead of the flat one evoqued in the 1st post. But again, it's difficult to know without some calculations, I think.

k5054
11-16-2004, 04:57 PM
We had a thread here with a RL test of a 109K, a 5g turn started at 180m/s 402mph true at 20,000ft.
He maintained 5g for 8 secs and then slowly eased off. The plane took 12secs to do 180 degrees, at which point it was at 157 m/s, 350mph. It lost a further 50mph in the next 180, at reduced g. These should be fairly typical numbers, for a turn without alt loss. Note that the opposing fighter will be 2.16 km away from the crossing point if he does not turn, and still have 180m/s, so you are 2.16 km behind, 1150m offset and 50mph slower than the guy who went straight on.

Fennec_P
11-16-2004, 05:44 PM
If you think there is no bleed, go down to ground level and see how fast you can turn b4 you pancake. You'll find that the sustained turn rate there matches the actual figures (or is at least close).

Granted, the planes don't wallow in long turns like modern jetfighters do, but they are not supposed to. A 10 ton, 60lb/ft, delta wing jet is not comparable to 4 ton, 35lb/ft, straight wing prop plane.

If you want something that will plow through turns, try a Me-262 with full tanks and a BK5.

Pr_Halios
11-16-2004, 05:52 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by k5054:
We had a thread here with a RL test of a 109K, a 5g turn started at 180m/s 402mph true at 20,000ft.
[...] Note that the opposing fighter will be 2.16 km away from the crossing point if he does not turn, and still have 180m/s, so you are 2.16 km behind, 1150m offset and 50mph slower than the guy who went straight on. <HR></BLOCKQUOTE>

Interesting, thanks for sharing.