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Author Topic: Wiki Speed and Climb Charts (P-51B)  (Read 2306 times)

Offline Strip

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Wiki Speed and Climb Charts (P-51B)
« on: June 21, 2009, 12:44:30 PM »
I have noticed some planes will not achieve the speeds listed in the charts. Like a P-51B will not maintain 400 mph at 30,000 feet. The chart, however, has it listed close to 450 mph?

Weight was identical and no droptanks.....

Thoughts?

(Is the air speed indicator in knots?)

Strip
« Last Edit: June 21, 2009, 01:08:21 PM by Strip »
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Offline Angus

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Re: Wiki Speed and Climb Charts
« Reply #1 on: June 21, 2009, 12:55:14 PM »
AFAIK the indicator would be in MPH. Are you sure that you are reading TAS?
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Offline Strip

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Re: Wiki Speed and Climb Charts
« Reply #2 on: June 21, 2009, 12:56:29 PM »
Ground speed and true airspeed....
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Offline thrila

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Re: Wiki Speed and Climb Charts
« Reply #3 on: June 21, 2009, 12:56:35 PM »
oops! ignore my post
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Offline Strip

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Re: Wiki Speed and Climb Charts
« Reply #4 on: June 21, 2009, 01:07:30 PM »
Does the P-51B have permanant racks for dt's?

IE Speed after droptanks jettisoned is equal to clean speed.
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Offline Widewing

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Re: Wiki Speed and Climb Charts
« Reply #5 on: June 21, 2009, 04:11:32 PM »
Quote from: Strip on June 21, 2009, 01:07:30 PM
Does the P-51B have permanant racks for dt's?

IE Speed after droptanks jettisoned is equal to clean speed.

Strip is right... The P-51B does not conform (not even close) to the Aces High speed chart at 30K for MIL power.

Measured max speed @ 30k
Military Power: 394 mph TAS (36 mph too slow)
Combat Power: 443 mph TAS (about right)

All of this is due to incorrect tables for MAP. The P-51B should pull about 48" MAP in MIL power at 30k. In game, it pulls only 27".

Pyro, this is a significant error.


My regards,

Widewing
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My regards,

Widewing

YGBSM. Retired Member of Aces High Trainer Corps, Past President of the DFC, retired from flying as Tredlite.

Offline Strip

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Re: Wiki Speed and Climb Charts
« Reply #6 on: June 21, 2009, 09:10:02 PM »
Quote from: Widewing on June 21, 2009, 04:11:32 PM
Strip is right... The P-51B does not conform (not even close) to the Aces High speed chart at 30K for MIL power.

Measured max speed @ 30k
Military Power: 394 mph TAS (36 mph too slow)
Combat Power: 443 mph TAS (about right)

All of this is due to incorrect tables for MAP. The P-51B should pull about 48" MAP in MIL power at 30k. In game, it pulls only 27".

Pyro, this is a significant error.


My regards,

Widewing

      Its interesting to note that I can pull 32.5" at military power at 30,000 feet along with only TAS of 391. I let mine settle for a good ten minutes so that might affect speed readings. However your getting 4.5 inches (+/- .5" or so) less than me.  Why is there a difference? You didnt put your WEP manifold but I pulled 50.5" (+/- .1" or so).

For clarity...... carrying dt's (and dropping them) shouldnt effect the drag profile of the P-51B correct?

Strips
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Offline Pyro

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Re: Wiki Speed and Climb Charts (P-51B)
« Reply #7 on: June 22, 2009, 12:47:17 PM »
Interesting, it looks like it's not making full power at high alts for some reason.  I'll take a look at what's causing the problem.
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Offline Die Hard

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Re: Wiki Speed and Climb Charts (P-51B)
« Reply #8 on: June 22, 2009, 01:21:42 PM »


 ;)
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Offline Widewing

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Re: Wiki Speed and Climb Charts
« Reply #9 on: June 22, 2009, 10:05:18 PM »
Quote from: Strip on June 21, 2009, 09:10:02 PM
      Its interesting to note that I can pull 32.5" at military power at 30,000 feet along with only TAS of 391. I let mine settle for a good ten minutes so that might affect speed readings. However your getting 4.5 inches (+/- .5" or so) less than me.  Why is there a difference? You didnt put your WEP manifold but I pulled 50.5" (+/- .1" or so).

For clarity...... carrying dt's (and dropping them) shouldnt effect the drag profile of the P-51B correct?

Strips

HTC models RAM. At 20 mph TAS on the 30k runway, MAP is 27". At 394 mph, MAP is 32.5".  I also see a tad over 50" in WEP at 443 mph. I filmed the test flight.

You are correct.. P-51 pylon drag is part of the basic drag. The pylons are not optional. Same rules apply for the P-47s, P-38s and several others.


My regards,

Widewing
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My regards,

Widewing

YGBSM. Retired Member of Aces High Trainer Corps, Past President of the DFC, retired from flying as Tredlite.

Offline Widewing

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Re: Wiki Speed and Climb Charts (P-51B)
« Reply #10 on: June 22, 2009, 10:25:21 PM »
Note also that the P-51D pulls 46" MAP at 20 mph TAS @ 30k, and a bit over 50" MAP at 424 mph @ 30k. There is no WEP related increase in MAP at 30k. Considering that the P-51B's V1650-3 used a supercharger geared for better high altitude performance, this brings the issue into bold relief. Critical altitude for the P-51D is 25k. Above 25K, the P-51B should be faster than the P-51D at both MIL power and WEP (combat) power.

My regards,

Widewing
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My regards,

Widewing

YGBSM. Retired Member of Aces High Trainer Corps, Past President of the DFC, retired from flying as Tredlite.

Offline pokecheck

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Re: Wiki Speed and Climb Charts (P-51B)
« Reply #11 on: June 28, 2009, 10:12:16 AM »
Quote from: Die Hard on June 22, 2009, 01:21:42 PM
(Image removed from quote.)

 ;)
 
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Offline Odee

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Re: Wiki Speed and Climb Charts (P-51B)
« Reply #12 on: July 16, 2009, 11:12:40 PM »
Quote from: pokecheck on June 28, 2009, 10:12:16 AM
 
Dude, WD-40 stops squeaks.I think I've solved our problems, just coat the forums in the stuff.
  Also great for cooking with
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Offline vonKrimm

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Re: Wiki Speed and Climb Charts (P-51B)
« Reply #13 on: July 17, 2009, 09:51:23 AM »
Quote from: Pyro on June 22, 2009, 12:47:17 PM
Interesting, it looks like it's not making full power at high alts for some reason.  I'll take a look at what's causing the problem.

Pyro, any update on this matter?
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Offline Strip

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Re: Wiki Speed and Climb Charts (P-51B)
« Reply #14 on: July 17, 2009, 10:31:41 AM »
No Pyro but its fixed for beta....

Tested it myself.
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