KiwiBiggles
Senior Airman
Oh God, it's started again.
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Oh God, it's started again.The 6689# is average fuel for the flight as I have explained before. I imagine the P-38 did have twice the drag as a P-39 and weighed 2.2x as much as this P-39. Fuel quoted was per engine on P-38.
The same BS posted on any thread that can be in any way linked to a P-39.Oh God, it's started again.
Sure. P-39Q with gondola wing guns at 15000' gets 6.8mpg at 204IAS/265 TASUnless you can come up with a document or statement that says they were using average fuel weight for tests I am not buying it.
We have given you the fuel consumption figures for the P-38 but since you don't like the results you choose to imagine that is has twice the drag.
weight is not drag as proved by the P-51 Allison Mustang
1130hp at 12,650ft for a 8824lb plane was 390mph. WIththis gun installation
View attachment 489374
strangely with only two cannon installed and no armor(?) it weighed 8114lbs the engine gave 20more HP and the plane picked up a whopping 6mph. Due to lighter weight or less drag?
http://www.wwiiaircraftperformance.org/mustang/P-51_41-37320_PHQ-M-19-1415-A.pdf
A P-38F clean at 15,000ft gets 5.7mpg at 190IAS/240 true.
..........................................3.57mpg at 225IAS/275 true.
...........................................3.0mpg at 255IAS/305 true.
as per the manual.
Care to tell use what the P-39 got at comparable speeds/altitudes?
Should Also note that the cog would Be Impacted and sorting That out will add weightHmmm, still doesn't solve the range problem.
Look at Russian fighters to get an idea of what they considered "devastating" Mig-3 one 12.7mm gun and two 7.62s. Early Laggs and Yaks, one 20mm and two 7.62mm. Some Yaks got one 20mm and one 12.7mm. La-5 had two 20mm guns, synchronised.
You are expecting "wonders" from the removal of 200lbs worth of guns and ammo and under 100lbs or armor.
Most other aircraft, while they did better with such a reduction in weight, did not move into the "wonder" catagory.
You could take a MK V Spit and strap a 90 imp gallon tank under it (790lbs) and only loose around 500fpm of climb and in fact climb to 20,000ft changed from 8 minutes to 10 minutes.
Taking out 300lbs from a 7600lb plane was not going to turn it into wonder plane
View attachment 489356
You are trying to prove that the P-38 used twice the amount of gas per mile so that it's mere 30 gallons of fuel more per engine doesn't really give it much greater range.Sure. P-39Q with gondola wing guns at 15000' gets 6.8mpg at 204IAS/265 TAS
5.5mpg at 219IAS/285TAS
4.2mpg at 247IAS/321TAS
Mine's bigger. What exactly are we trying to prove?
...
By the way, do you have a P-38F/G manual? Would you mind sharing the Flight Operation Instruction Chart pages (clean and w/drop tanks)? Thanks in advance.
Thank you.Here: link.
Not trying to prove anything, you asked and I replied. All I said was the P-38 only had 21 more usable gallons of internal fuel per engine than a P-39. Then you went all numbers on me. If plane A gets 4MPG and plane B gets 3MPG then then plane A will go farther on the same amount of gas (or the same distance on fewer gallons of gas).You are trying to prove that the P-38 used twice the amount of gas per mile so that it's mere 30 gallons of fuel more per engine doesn't really give it much greater range.
But the fuel isn't figured at fuel per engine in this case. The P-38s fuel consumption is for the airplane/both engines so
P-39's 219 IAS/285 true is 5.5 mpg and that is not twice the 3.57mpg of the P-38 at 225IAS/275 true.
please note the difference between the IAS and true speeds. True speeds are from the P-38 manual chart and not a calculator. Perhaps the chart is wrong but that only makes the P-38 number better.
P-39's 247/321 true is 4.2 and that is not double the P-38s manual 255IAS/305 true of 3.0 mpg.
Please note if I use an online TAS calculator for 255IAS I get 331.5 true for a mileage of 3.28miles per gallon.
So no, the P-38 does not use twice as much fuel per mile just because it has twin engines and weighs twice as much.
Its that deja vu all over again.Facts do try to get in the way of things
Not trying to prove anything, you asked and I replied. All I said was the P-38 only had 21 more usable gallons of internal fuel per engine than a P-39. Then you went all numbers on me. If plane A gets 4MPG and plane B gets 3MPG then then plane A will go farther on the same amount of gas (or the same distance on fewer gallons of gas).
I updated my little handmade chart for you. The P-40E weight was updated from 8400# to 8280# from the Wm. Green book. It's still light when tested. The P-38, P-39, P-40 and P-47 were all lighter in official tests than published weights. If you discount the P-39 numbers then you should discount all the other planes numbers too.The climb figures were for a plane grossing 6689 lbs.
You want to use a the numbers from WWII Aircraft Performance
Use them but don't twist them.
Of course we will totally disregard the FACT that the P-38 did NOT have TWICE the drag of the P-39 and therefore did not need TWICE the fuel to fo the same distance????
I imagine the P-38 did have twice the drag as a P-39
Twice the horsepower at the same speed means twice the drag.I actually can't believe that I'm saying this but the expert may have a point here, but only if we choose to believe that equivalent flat plate area (f) is truly indicative of an aircraft's aerodynamic cleanliness (I for one am not sold on it yet). In Table 96 of America's Hundred-Thousand, Dean lists the P-39N at 4.63 and the P-38J at 8.84 square feet respectively. He also states that the airplane with the lowest figure in this regard will require less engine power to attain a given speed. While this may be true, I don't see what wing area has to do with overall cleanliness, because with it a Sopwith Camel can be considered more aerodynamically refined than a Concorde jet!