Aces High Bulletin Board
General Forums => Aircraft and Vehicles => Topic started by: Old Sport on May 02, 2011, 10:29:48 AM
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At the bottom of the page of America's Hundred Thousand we're told the P-38L could develop 1600 BHP per engine in WEP at SL, though without mentioning top speed.
(http://i740.photobucket.com/albums/xx48/Ironman5459/Accscan.jpg)
At the following site for "P-38L Airplane, AAF No. 44-25092 performance tests" we're told:
"true speed at sea level at war emergency power, 1530 BHP and 3000 RPM, was 342 MPH"
http://www.wwiiaircraftperformance.org/p-38/p-38.html
I tested a P-38L at half tanks and started the WEP run at 16,280 lbs down to 16,170 - and got a max of 345 mph a few seconds before WEP ran out. This is lighter than the AHT test. I couldn't find a weight listed for the SL WEP 1530 BHP 3000 RPM 342 mph, but probably wasn't far from this.
So, any of you Lockheed geeks, is the AH P-38L making a full 1600 BHP per engine? Is the reference in AHT for 1600 BHP reliable?
Best regards.
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In gathering data on planes it almost always will get you into trouble if you pull try pull different data points form multiple sources, I.E. HP from one Speed from another and Climb from another.
HiTech
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a friend of mine worked at lockheed and did minor work on the b2 bomber,i asked about your question and he said"LOL LOL we won the war,we can print anything we want and MAKE it true,do you really think WE came up with the idea for a flying wing too? i asked him to explain, and he cited variables that are not in the books we read..such as temperature,humidity,weather the sun was shining directly on test aircraft,etc etc. he said those old test were so out of whack that they instituted a new std of tests at lockheed. when designing aircraft parts are now put in the "waterfall" a static test that pours water over the surface and than those numbers are converted as to what air will do and then actually backed up in a real test flight when assy is finished.and so goes the process today. back in the 40's other factors also contributed to test number results....one was contracts. you could fuge the results slightly by running a little light on fuel,or ommitting certain equip....like o2 bottles for low tests etc. on paper these results became fact and were then quoted over and over.politicians made the final call without ever having seen the aircraft. so i then asked,well how much can stats be off? and he said between 2-4% and thats coming from a lockhead engineer.
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In gathering data on planes it almost always will get you into trouble if you pull try pull different data points form multiple sources, I.E. HP from one Speed from another and Climb from another.
HiTech
HiTech,
Do you have what you would consider reliable data on the P-63C or P-63A? Based on what you have, how would it be modelled in AH for Speed & Climb? I've had a very hard time locating any Army test data, particularly on the C variant. :salute
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In gathering data on planes it almost always will get you into trouble if you pull try pull different data points form multiple sources, I.E. HP from one Speed from another and Climb from another.
HiTech
Very true.
I also do not know the weight of the 1530 BHP and 3000 RPM, was 342 MPH test plane, nor do I have a copy of AHT and so do not know if it's claims are reliable. Which is why I asked about that.
I was also able to get 419 mph at 26,200 which is slightly higher than many references of 414 mph, and slightly lower than the highest speeds I've seen listed at 421 mph.
These issues are not gonna break my bank one way or the other. I was just curious.
Best.
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HiTech,
Do you have what you would consider reliable data on the P-63C or P-63A? Based on what you have, how would it be modelled in AH for Speed & Climb? I've had a very hard time locating any Army test data, particularly on the C variant. :salute
Probably the best single source I've come across so far on the P-39 and P-63's is "Cobra! Bell Aircraft Corporation 1934-1946" by Birch Mathews (ISBN: 0887409113)
http://www.abebooks.com/servlet/SearchResults?isbn=0887409113&sts=t&x=77&y=13 (http://www.abebooks.com/servlet/SearchResults?isbn=0887409113&sts=t&x=77&y=13)
On page 189 is lists data from a report Serial No. 6-43-5-4 comparing speed of the P-63A-1 to the P-47D-20, P-38J-15, and P-51B-5 (no mention of weights)
Speed @ 10K: 372mph
Speed @ 20K: 397
Speed @ 25K: 397
Speed @ 30K: 398
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Probably the best single source I've come across so far on the P-39 and P-63's is "Cobra! Bell Aircraft Corporation 1934-1946" by Birch Mathews (ISBN: 0887409113)
http://www.abebooks.com/servlet/SearchResults?isbn=0887409113&sts=t&x=77&y=13 (http://www.abebooks.com/servlet/SearchResults?isbn=0887409113&sts=t&x=77&y=13)
On page 189 is lists data from a report Serial No. 6-43-5-4 comparing speed of the P-63A-1 to the P-47D-20, P-38J-15, and P-51B-5 (no mention of weights)
Speed @ 10K: 372mph
Speed @ 20K: 397
Speed @ 25K: 397
Speed @ 30K: 398
Thanks Soulyss. I have that book as well, but it stops at teh A-varient without ADI. There are HP numbers listed for ADI engines through the C-variant, but no plane performace numbers [speed pr climb]. For example the -117 engine with ADI is listed in mathiews book at 1800hp, but there is no speed or climb data for that HP rating. :salute
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Wonder how much BHP will give the L a climb rate of 20,000 ft per minute, per Lockheed-Martin's website.
http://www.lockheedmartin.com/aboutus/history/P38Lightning.html
:aok
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Wonder how much BHP will give the L a climb rate of 20,000 ft per minute, per Lockheed-Martin's website.
http://www.lockheedmartin.com/aboutus/history/P38Lightning.html
:aok
Now thats a climb rate... 227.28 miles per hour straight vertical! :O
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Wonder how much BHP will give the L a climb rate of 20,000 ft per minute, per Lockheed-Martin's website.
http://www.lockheedmartin.com/aboutus/history/P38Lightning.html
:aok
I knew the FM here was wrong. :)
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In gathering data on planes it almost always will get you into trouble if you pull try pull different data points form multiple sources, I.E. HP from one Speed from another and Climb from another.
HiTech
This is why I always thought a lot of the data on Russian rides was, how shall I say it - "massaged", by the Soviets in the history books before being released.
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This is why I always thought a lot of the data on Russian rides was, how shall I say it - "massaged", by the Soviets in the history books before being released.
I wouldn't be surprised if all the countries did that. Every country engages in propaganda.
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This is why I always thought a lot of the data on Russian rides was, how shall I say it - "massaged", by the Soviets in the history books before being released.
Interesting bit of corroberation on La-5 and La-7 performce comes from gunther Rall's memior in which he states that his Bf-109 was "unable to overtake the late maodel plane produced by Lavochkin."
Perhaps not so massaged afterall. ;)
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Now thats a climb rate... 227.28 miles per hour straight vertical! :O
That figure, curiously enough is the same as the max climb rate for the Brit Lightning jet fighter and about 4x greater than anything remotely possible however stripped for the P-38L.
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In gathering data on planes it almost always will get you into trouble if you pull try pull different data points form multiple sources, I.E. HP from one Speed from another and Climb from another.
HiTech
All true HiTech. IMO however, Mike Williams' site is the best single source for performance data for US fighter performance data because there are a.) usually explicit data regarding Take Off Gross Weight, BHp taken from official bench test and flight test data to give an 'accurate' Bhp vs Altitude reference' for different Boost and Rpm data, Speed runs (usually many - and often plots shown), Tabular data to link speed, altitude, weight, Bhp, High/Low Blower critical altitude, etc.
For those of that often waste enormous time calculating drag form these runs the SL data is the best way to get to level flight, low AoA, Parasite Drag.
On another forum I did this to present to a P38 advocate the reasons that the P-38 did not win the cross country Bendix Trophy Races - and showed him a.) why the P-51B and D had 2/3 the Parasite Drag and b.) why the P-38L (and J) were running into compressibility drag at a lower speed than the P-51 at 25,000 feet. The 38 is actually running into Divergence realm at ~ .6M presumably because of the fat wing and possibly the radiator intakes.