FLYBOYJ
"THE GREAT GAZOO"
Is this indicated in any performance chart?
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Is this indicated in any performance chart?If you make up a Spitfire VIII using the various maximum size fuel tanks ever fitted to Merlin Spitfires with the external and/or rear fuselage tanks able to refill the main tanks after take off, the theoretical combat radius comes to around 500 miles, cruising all the way at maximum weak-mixture power setting of 320 mph at 20,000 feet using 66 gallons per hour, corresponding with an engine setting of 2,400 rpm, +4 lbs boost. Which translates to much but not all of Germany when based in England, taking direct courses. The requirements for combat, reserves and the need to burn off some of the rear fuselage fuel before combat means the external fuel limit is about 90 gallons.
theoretical combat radius comes to around 500 miles, cruising all the way at maximum weak-mixture power setting of 320 mph at 20,000 feet using 66 gallons per hour,
It doesn't matter what the external fuel was, It the British wanted they could have come up with a 120 IMP gal drop tank.The requirements for combat, reserves and the need to burn off some of the rear fuselage fuel before combat means the external fuel limit is about 90 gallons.
That chart s wrong on so many levels. The Combat Radius for the P-47C without belly tank was 125+ mi CR. The Combat Radius of the P-47C/D with 75 gal c/l tank was 230mi (Aug 1943),with 2x150gal pylon tanks was 425mi circa March/April 1944. These values for 25K cruise zone altitude.
When the Ministry of Aircraft Production began reporting external fuel tank production in December 1943 Spitfire 90 gallon tanks were being made at about 500 per month.
Dean Published the AAF Combat Radius Tables for several of the conditions above. Reference pp 599-600.Also note the differences between 10K and 25K altiude with 10K cruise achieving a delta of ~+25-50mi for in-line. His source for the 'practical' Combat radius was developed by USAAF at Wright Field 1943-1945.That chart appears to be based on the charts published in the document Eighth Air Force Tactical Development August 1942–May 1945 (Chart A and B, p.97 of document, p.119 of PDF). Below is what is shown on Chart A for the P-47:
May 1943 = 175 miles
June 1943 = 230 miles
July 1943 = 340 miles (1 x 75-gallon drop tank)
Aug. 1943 = 375 miles (1 x 108-gallon drop tank) (+33 gallons, +35 miles compared to 1 x 75-gallon)
Feb. 1944 = 425 miles (1 x 150-gallon drop tank) (+42 gallons, +50 miles compared to 1 x 108-gallon)
Feb. 1944 = 475 miles (2 x 108-gallon drop tanks) (+66 gallons, +50 miles compared to 1 x 150-gallon)
The increases are roughly one mile per additional gallon carried when drop tanks are used.
The accompanying text which describes the figures shown on the chart, however, says the 475-mile range was achieved with 2 x 150-gallon tanks. I think that text is a typo, as only an additional 50 miles is gained despite carrying an additional 150 gallons, which is out of place with the gains made from the prior drop tanks.
Dean Published the AAF Combat Radius Tables for several of the conditions above. Reference pp 599-600.Also note the differences between 10K and 25K altiude with 10K cruise achieving a delta of ~+25-50mi for in-line. His source for the 'practical' Combat radius was developed by USAAF at Wright Field 1943-1945.
Yes if you are referring to the fuel consumption. Cruise 320 mph TAS at 20,000 ft, corresponds with an engine setting of 2,400 rpm, +4 lbs boost, consumption 66 gallons per hour. In the following I will add 20 gallons for a reserve, which would be around 30 minutes at 170 mph IAS. And ignore the obvious consumption penalties for carrying external loads, hauling a heavier load to altitude, penalties for formation flying, variations between individual aircraft and pilots when it came to fuel consumption, or an allowance for faulty navigation. Or the gains from using economic cruise for part of the outbound and returnIs this indicated in any performance chart?
The RAF allocation was 23 gallons for take-off and climb to 20,000 ft and 36 gallons for 15 minutes of combat, where do the figures quoted above come from?It doesn't matter what the external fuel was, ... It the British wanted they could have come up with a 120 IMP gal drop tank.What mattered was the roughly 54 Imp gal for the combat allowance and the 10-15 gal reserve for finding your own (or any) airfield after crossing the coast. Also the wind was usually coming from the west. ... It is going to take 25-30 gallons just to warm up - takeoff - climb to 25,000ft
As I have been using. Spitfire VIII 124 gallons internal.Your operational radius was the distance you could fly at the desired exit speed/s after combat and before having to hunt for a friendly airfield.
Exactly, we don't need to fly to Berlin or do anything fancy, just get the Spit into Germany late '42 onwards, P47's saw continuous air combat with the limited range they had, the Spit could have joined them.Keeping the Spitfire able to reach about as far as the P-47 as the aim, given how much combat the P-47 saw in the time period.
As long as the subject has been beaten to death, the primary issue is that the Combat Radius as defined, is a straight line optimal climb from take off to cruise, cruise, fight and return.For what it's worth, Eighth Air Force Tactical Development August 1942–May 1945 was prepared by the Eighth Air Force and the Army Air Forces Evaluation Board (European Theater of Operations) and published in July 1945.
So it seems there are different sets of figures from what would seem to be official sources.
It doesn't matter what the external fuel was, It the British wanted they could have come up with a 120 IMP gal drop tank.
What mattered was the roughly 54 Imp gal for the combat allowance and the 10-15 gal reserve for finding your own (or any) airfield after crossing the coast. Also the wind was usually coming from the west.
Your operational radius was the distance you could fly at the desired exit speed/s after combat and before having to hunt for a friendly airfield.
Again provisional numbers for the P-51B are 315mph at 20,000ft using 36imp gals GPH clean and 329mph at 20,000ft using 51 GPH with the pair of 75 US gallon drop tanks.
I am sure the Spit would show a difference with and without the drop tanks. A newer manual could very well show a difference in the P-51 numbers.
It is going to take 25-30 gallons just to warm up - takeoff - climb to 25,000ft (doesn't include form up on the charts but lets assume it does) so that takes care off most of the burn off of the rear tanks to get close to combat capacity. Warm up/take off is done on the main tank/s but any fuel over flow in cruise is routed back to the main tank/s so they are full or near fuel after a couple of hours.
As long as the subject has been beaten to death . . .
Another consideration for you in your own analysis - is to look at the encounter reports and note that almost zero P-47 Victory credits and MACRS were beyond the target for their escorted bombers. These docs paint a clearer picture of the radius of action to return to base on remaining internal fuel after a fight. Those reports are a clearer Practical marker for the mission planning application of 'real Combat Radius' vs 8th AF or MC publications.
Only when the P-47D-25 with 370gal internal were the 'extended CR' feasible.
The longet mission I found in 1944 for P-47D-25+ (with 370 gal + 2x150s) was Oct 7, 1944 when the 78th swept to Leipzig and Dec 4 when 56th swept to W/Brandenburg.
Both but mostly 'flat' because it could be attached to C/L ack, whereas the round crosssection 150 was a potential hazard. Kenney was 'different' from Eaker/Doolittle in command style,Perhaps so, but I still find the discussion useful precisely because the sources differ on the figures, and only by discussing it can such differences be sorted out and the truth, however imperfectly, approached.
Alas, I don't have access to archives I can visit in person, so I'm limited to what has been digitized and posted online. This is both great and frustrating. It's great in that I can view information I'd probably never be able to see otherwise, but it's frustrating because there is still so much material that has yet to be digitized. That said, I'm thankful for everything that has been digitized and made more readily accessible.
Were these the 'flat' 150-gallon tanks or the P-38's teardrop-shaped tanks? The 150/165-gallon P-38 tanks were definitely used in the Pacific by P-47s, based on photos of wartime P-47 units in the PTO.
I think this is best chart. Racks only Cruise - 2050RPM 29" 52gph 303mph for 25K http://www.wwiiaircraftperformance.org/mustang/P-51D_15342_AppendixB.pdfI don't think you will see 315 mph @ 36 gph @ 20,000 feet. Maybe 56 gph, but not 36 gph unless you are at sea level, 1600 rpm, and 220 mph.
He's another idea, lets forget the escorting in 1942-43, just send Spit V's and P47's out as far as they can go, say 200 miles and let MkIX's go as far as they can go which will be over 400 miles, instead of escorting per say lets make them fighter sweeps so they can fly at their best altitude an speed, the Luftwaffe are going to engage if there is a bomber mission going on so the fighters can engage independently of they are doing.Despite having 108 gal external, the escort was not going past Quackenbruck, Lingen and Munster in October, so AFAIK Bremen Target Escort (optimal as little essing performed
He's another idea, lets forget the escorting in 1942-43, just send Spit V's and P47's out as far as they can go, say 200 miles and let MkIX's go as far as they can go which will be over 400 miles, instead of escorting per say lets make them fighter sweeps so they can fly at their best altitude an speed, the Luftwaffe are going to engage if there is a bomber mission going on so the fighters can engage independently of they are doing.
About the 42nd time somebody has suggested thisHere's a better idea: put a Merlin into a P-51 airframe in early 1941 instead of late 1942.
just send Spit V's and P47's out as far as they can go, say 200 miles and let MkIX's go as far as they can go which will be over 400 miles, instead of escorting per say lets make them fighter sweeps so they can fly at their best altitude an speed,
About the 42nd time somebody has suggested this