Aces High Bulletin Board

General Forums => Aces High General Discussion => Topic started by: sullie363 on March 30, 2005, 12:44:56 PM

Title: Sullie's Official Request 3: P-51 Thrust Assist
Post by: sullie363 on March 30, 2005, 12:44:56 PM: I highly suggest that when the P-51s get eventually reworked that their ability to produce a jet type thrust be added. A hot air exit ramp sat at the back of the intake and provided thrust. While I couldn't find numbers specific to the Mustang, similar systems on other aircraft produced 500 lbs of thrust. Curtiss wanted to incorporate an intake/cooling ramp design into the P-40 but never did. It is argued that North American used Curtiss research in the design of the NA-73X (Mustang prototype).

It only makes sense that if you guys are going to take the time to rework all the aircraft, you might as well make them as accurate as possible. I know I wasn't able to provide much information so anything anyone else can provide would be appreciated.

(http://www.supercoolprops.com/images/15resize.gif)
Title: Sullie's Official Request 3: P-51 Thrust Assist
Post by: Howitzer on March 30, 2005, 03:55:52 PM: I believe the D was the first plane that was redone for AH2.
Title: Sullie's Official Request 3: P-51 Thrust Assist
Post by: RedDg on March 30, 2005, 04:19:43 PM: High blower engages!
Title: Sullie's Official Request 3: P-51 Thrust Assist
Post by: Karnak on March 30, 2005, 04:29:01 PM: If that thrust were not already in the game the P-51 would top out at ~400mph. Given its actual speed it is obvious that the thrust is modeled.
Title: Sullie's Official Request 3: P-51 Thrust Assist
Post by: sullie363 on March 30, 2005, 06:07:46 PM: If the effect is modeled, then the ramp itself isn't. It should drop down via a piston as depicted in the picture.
Title: Sullie's Official Request 3: P-51 Thrust Assist
Post by: Karnak on March 30, 2005, 07:00:42 PM: Quote
Originally posted by sullie363
If the effect is modeled, then the ramp itself isn't. It should drop down via a piston as depicted in the picture.

I'm sure that is not modeled, but that is just graphics and has no effect on the flight model.
Title: Sullie's Official Request 3: P-51 Thrust Assist
Post by: Kweassa on March 30, 2005, 09:16:19 PM: There was an interesting post in IL2/FB forums way back, when Oleg posted the data from RAF testings of the Mustang Mk.I(or mebbe it wuz II or III.. I'm sure the test report fetish guys would instantly realize what I'm mentioning :D ).

IIRC, the RAF Mustang recorded only about 414mph, and was noted for being overheating very quickly. Many people translate this as the RAF Mustang being tested with its radiators closed, which in the RAF was the standard procedure for testing maximum speed of the plane(since most planes obtain their maximum speed with the radiator/cowl flaps closed to minimize drag).

So, like Karnak said, the said effect is (probably) already in the game. But its just not visually represented, such as once the 109 slats were in effect but not visually represented in the old AH.

It'd be cool to see working rad/cowl flaps. (but that would also mean rad/cowl flap control would be needed in the game)
Title: Sullie's Official Request 3: P-51 Thrust Assist
Post by: hubsonfire on March 30, 2005, 09:36:41 PM: I'm a bit puzzled here. Does this boost come from the cold (dense) air charge leeching the heat from the cooling system, expanding, and exiting out the rear?

Some kind of venturi effect?
Title: Sullie's Official Request 3: P-51 Thrust Assist
Post by: Kweassa on March 30, 2005, 09:47:01 PM: I've heard some people mentioning RAMAIR effect..

Which by the way, I have no idea what it is. :D
Title: Sullie's Official Request 3: P-51 Thrust Assist
Post by: hubsonfire on March 30, 2005, 09:52:02 PM: Ramair (at least with cars) uses ductwork or the position of the air intake for the engine itself so that as the vehicle moves faster, it not only draws air in on the intake stroke, but air is effectively charged by the movement of the vehicle itself. Since this is not an air intake, but rather a remotely located duct for a remotely located cooler(s), I don't think ramair is a good way to describe it. Now I'm really curious.

Hmmm, i need a beer.
Title: Sullie's Official Request 3: P-51 Thrust Assist
Post by: Blue Mako on March 30, 2005, 10:26:18 PM: Quote
Originally posted by hubsonfire
I'm a bit puzzled here. Does this boost come from the cold (dense) air charge leeching the heat from the cooling system, expanding, and exiting out the rear?

Some kind of venturi effect?

The engine cooling system on the P51 acted like a simple jet engine. Cool low pressure air came in the front of the scoop, was used to cool the radiator (ie. heat was added to the air and removed from the radiator) and the air compressed as it slowed through the radiator. The added heat caused the air to expand and clever use of the exit duct as a simple nozzle provided a relatively small amount of jet thrust.
Title: Sullie's Official Request 3: P-51 Thrust Assist
Post by: Golfer on March 30, 2005, 10:50:32 PM: Quote
a relatively small amount of jet thrust.

Spot on. Such a small amount of thrust it made up for the drag of the scoop being there so there was no net loss in performance. It's not like Jimmy Franklin's jet Waco...

(http://www.onpoi.net/ah/pics/users/621_1112244836_franklinwaco.jpg)
Title: Sullie's Official Request 3: P-51 Thrust Assist
Post by: LePaul on March 30, 2005, 11:32:49 PM: Im glad someone else said that, I'd heard something similar, that the output "thrust" from the hot air exiting the cooling cowl "cancelled out" the drag the intake scoop created.

My source was my flight instructor, when he was talking about "neat things" about late WW2 fighters. As for anything from great aerodynamic minds, I havent a clue.