P-51 fuselage fuel tank

[PAT303]

Shucks, the Spit never even had a decent capability for drop tanks. The Spit IX could carry two 500 lb bombs over an absurdly short distance, but they never hung more than that little "slipper" tank under the belly operationally.

Such a waste of a good aero plane, but what do you expect when this is considered a good idea.

 

[drgondog]

From what I've read the trim couldn't be set and the plane couldn't be flown hands off with a full rear tank and all maneuvers done with extreme caution, once down to 35G it was business as usual. There seems to be a line between acceptable and difficult handling around the 40G mark.

you are correct about hands off instability, but for the Mustang even in full trim, it would 'wander' hands off. Extreme caution for a full tank was basically 'gentle' stick. Any abrupt movement of the stick was not advised, but missions were made with full/near full aft tank, with appropriate cautions for take off and formation assembly before switching from L.Main to Fuse tank. Additionally internal baffles were installed after the November 1943 flight test report for 43-12188/89/90, which improved flying control.

I have heard of, but not verified, of field mods to move carb return overflow to fuse tank and change procedure of warming up, taxi and take off to fuse tank but have not seen a T.O. or an engineering drawing to confirm.

Bob weights were also installed post April 1944.

 

[tomo pauk]

Shucks, the Spit never even had a decent capability for drop tanks.

There were 170 imp gal (~200 US gal) tanks, used on Spitfires.

 

[PAT303]

you are correct about hands off instability, but for the Mustang even in full trim, it would 'wander' hands off. Extreme caution for a full tank was basically 'gentle' stick. Any abrupt movement of the stick was not advised, but missions were made with full/near full aft tank, with appropriate cautions for take off and formation assembly before switching from L.Main to Fuse tank. Additionally internal baffles were installed after the November 1943 flight test report for 43-12188/89/90, which improved flying control.

I have heard of, but not verified, of field mods to move carb return overflow to fuse tank and change procedure of warming up, taxi and take off to fuse tank but have not seen a T.O. or an engineering drawing to confirm.

Bob weights were also installed post April 1944.

Thats the difference between the Americans and British, the British found excuses as to why they couldn't do it, the Yanks just got on with it.

 

[PAT303]

There were 170 imp gal (~200 US gal) tanks, used on Spitfires.

Ferry tanks which are a waste of time for escort missions, the main 96G tank with 75G rear aux, replace the 13G per side leading edge tanks with 26G per side and a 90G or 100G torpedo dropper and your set, warm up take off and climb over the channel on the rear upper aux tank so handling is restored crossing the French coast, switch to dropper and go out 450 miles looking for trouble with 52G available for combat 96G getting home and 35G reserve, hand over to the P51's for the last 100 miles to Berlin then pick them up again on the way out.

 

[tomo pauk]

Ferry tanks which are a waste of time for escort missions, the main 96G tank with 75G rear aux, replace the 13G per side leading edge tanks with 26G per side and a 90G or 100G torpedo dropper and your set, warm up take off and climb over the channel on the rear upper aux tank so handling is restored crossing the French coast, switch to dropper and go out 450 miles looking for trouble with 52G available for combat 96G getting home and 35G reserve, hand over to the P51's for the last 100 miles to Berlin then pick them up again on the way out.

I'm aware of the math.
My point was to note that Spitfire have had a decent ability to carry drop tanks - unlike what was stated by another fellow forumite.

 

[Reluctant Poster]

Thats the difference between the Americans and British, the British found excuses as to why they couldn't do it, the Yanks just got on with it.

The British had other priorities. Also I would assume that the US would prefer to do it all by themselves.

 

[Shortround6]

I would note that were a few aircraft around the world that were certified in one country but not in another and that standards change with time.
Maybe a rumor but I think the DC-3 would not be eligible for certification under todays standards at aft CG loading?

Also most safety rules are the result of someone or a lot of someone's dying.
The Sopwith Camel was a great fighter, it also may have killed more British pilots than it killed Germans?
And we have the Botha. Were the dividing line is between rear CG problems I don't know.

 

[jimh]

Just from a modern day perspective...a gallon of aviation fuel is roughly 6lbs...85*6 is 510lbs. In Betty Jane we were around 6,500-7000lbs, that's 4000lbs under gross weight, give or take. But, a tailheavy airplane is a tail heavy airplane. The addition of the rear instrument package, seat structure and a 220lb (average weight) passenger could be considered a rear tank half full of gas. The airplane was completely stable. We didn't pull more than 4.5-5gs but never had any indication of instability or "snatch". The controls in a Mustang are balanced but mildly heavy, even being aggressive you can't yank the stick around like a Pitts Special. The stall, even an accelerated stall gives you a ton of warning and recovers with even slight release of back pressure. The Mustang also has a powerful trim system...once in cruise flight you can set it and fly basically hands off, particulary in smooth air. The only time you have to re-trim the airplane is during power changes. I understand the wartime warnings and SOP regarding the fuse tank and aft CG...but it boils down to how you fly the airplane and knowing the complete envelope. The policy of burning off the fuse tank first served it's purpose. The Merlin burns a gallon a minute in cruise and varies at climb power settings...roughly an hours worth of fuel, which would get them to altitude and pretty close to any combat area, where they could switch to the drops.

jim

 

[MIflyer]

Maybe a rumor but I think the DC-3 would not be eligible for certification under todays standards at aft CG loading?

Aircraft certification categories changed just after WW2. For example, the Ercoupe 415C was certified at 1240 lb gross weight in 1940 and the introduction of new categories enabled the same basic airframe to be certified at a higher gross weight but without major structural improvements. The upper forward fuselage from the cockpit to the firewall had to be fabricated out of steel rather than aluminum but this was a consequence of the change to the Continental flat four engine rather than the inverted in-line engine employed for the prototype. There also had to be a minor modification to the landing gear to handle the higher gross weight and the elevator travel had to be limited to prevent excessive G loads.

 

[pbehn]

Thats the difference between the Americans and British, the British found excuses as to why they couldn't do it, the Yanks just got on with it.

That is a strange statement to make in a strange discussion. especially regarding the British, the Americans and the Spitfire and Mustang / P-51. The Americans didnt get on with the Mustang, some tried to kill it before birth. The British were responsible for many qualities it had, like range and hard points and some that it didnt have, like higher speed due to a proposed shorter wing span. The Spitfire was always slated for replacement by the Typhoon and Tornado but the engines werent as good as proposed. However the British did receive many Mustangs of all types, and the Typhoon eventually did become a fighter bomber. In my opinion the reason the Spitfire wasnt given the range that it could have been was because in many cases it wasnt needed and so more short range versions weere preferred to fewer long ranged types.

 

[PAT303]

In my opinion the reason the Spitfire wasnt given the range that it could have been was because in many cases it wasnt needed and so more short range versions weere preferred to fewer long ranged types.

That's a strange statement to make when the single biggest criticism of the Spitfire was it's lack of range.

 

[pbehn]

That's a strange statement to make when the single biggest criticism of the Spitfire was it's lack of range.

Lack of numbers was the issue at the time, that is why the Mk V was produced instead of the Mk III and the Mk IX was produced instead of the Mk VII and VIII. Post D Day airfields were built in France within days because when the fight is over a land border you want to shorten it as much as possible, having planes return from a battle zone over 100 miles of water isnt ideal. Range is much more of an issue in todays discussions than it was then.

 

[PAT303]

Lack of numbers was the issue at the time, that is why the Mk V was produced instead of the Mk III and the Mk IX was produced instead of the Mk VII and VIII. Post D Day airfields were built in France within days because when the fight is over a land border you want to shorten it as much as possible, having planes return from a battle zone over 100 miles of water isnt ideal. Range is much more of an issue in todays discussions than it was then.

The lack of range kept the Spitfire out of more battles than it participated in where's the Americans put aux tanks or droppers on everything they flew, like I said, they just recognised the need and got on with it, that's further illustrated by the way they took two MkIX's and experimented with them before starting on the Mustang and developing it into the premier WW2 long range fighter, that shows their forward thinking on how air fighting was able to dictate future battles. The more you read about the P51 the more you realise just what a handful it was with a full tankerage of fuel but that didn't persuade them from doing it.

 

[MIflyer]

The US military had been putting drop tanks on fighters for years before WW2 and also had provisions for "Overload fuel" that would not be suitable for combat but would extend the range of fighter aircraft . If the USAAC had built fighters with European style ranges they would have been embarrassed to find they could not even make it out of Texas without stopping to gas up. Bill Gunston wrote of one postwar British jet fighter for which it was argued, "This is Europe! We don't build long range fighters!"

 

[PAT303]

The US military had been putting drop tanks on fighters for years before WW2 and also had provisions for "Overload fuel" that would not be suitable for combat but would extend the range of fighter aircraft

P47's were fitted with unpressurised ferry tanks when Spitfires were coming off the production lines with a 85G main tank. Sydney Cotton fitted a 20G seat tank in his PR ''Cotton Specials'', that tank alone would have totally changed the dynamic of how the BoB could have been fought.

 

[Geoffrey Sinclair]

For the RAF the Battle of Britain was much more about pilot endurance rather then aircraft, with the size of the Luftwaffe the RAF normally had to hold back part of the fighter force as reserves, the ability of the defence to exploit longer range fighters required much better intelligence on what the Luftwaffe was up to.

Part of this is the state of mind, for an escorted 1941 raid on Rotterdam at least 1 Blenheim was tasked with providing fighter navigation, similar for the raid on Cologne, the carrier launched Hurricanes sent to Malta and the ferry flights across Africa from Takoradi, apart from the engineering limits of long range there was the pilot training, in 1941/42 the RAF needed pilot numbers.

According to Morgan and Shacklady the trials of Spitfire overload tanks started in 1939, trials of the 170 gallon ferry tank in early 1942. A 29 gallon rear fuselage ferry tank for the mark V was approved on 7 July 1942. Also that the 90 gallon blister external tank had about the same drag as the 170 gallon torpedo type.

The USAAF long range Spitfire IX modifications weakened the wing structure and did not arrive in Britain until 1944, by which stage rear fuselage tanks were being or soon about to be fitted to Spitfires.

At the end of 1942 the RAF introduced its longest range Spitfire yet, the mark VIII at 660 miles, compared with the mark I at 575 miles. The fighting fronts from around 1940 onwards had been asking/pleading/demanding Spitfires and especially the latest type, this continued to around the second half of 1943 when the P-47 and P-51 proved combat worthy. Castle Bromwich built 2,707 Spitfires in 1943 and by 1943 the British economy was tightly stretched, inevitably losing production of Spitfires in early/mid 1943 to move Castle Bromwich over to a long(er) range airframe was a very big decision.

There is no doubt just using the Supermarine factory output of Spitfire VIII plus the 90 gallon external tanks the allies could have provided the 8th Air Force with a useful increase in long range (mid 1943 definition) to medium range (late 1943 definition) escorts, but someone had to offer and/or someone had to ask. Add the cross air force issues, a reason why the USAAF did not do defence of Britain.

Attached, what theory told the RAAF about Spitfire VIII range under Pacific Theatre conditions.

 

[Reluctant Poster]

The US military had been putting drop tanks on fighters for years before WW2 and also had provisions for "Overload fuel" that would not be suitable for combat but would extend the range of fighter aircraft . If the USAAC had built fighters with European style ranges they would have been embarrassed to find they could not even make it out of Texas without stopping to gas up. Bill Gunston wrote of one postwar British jet fighter for which it was argued, "This is Europe! We don't build long range fighters!"

The British didn't have to fly across Texas. The enemy was on their doorstep and he was more than willing to come to them. The USA had the luxury of being out of bombing range. When your factories and your civilian population are in grave danger your priorities are completely different. Who cares how far your plane can travel if it can't get up to altitude in time to successfully intercept. The Spitfire was designed as an interceptor and was very successful in that role.
The USAAC may have experimented with drop tanks pre WWII but that entered the war without any such capability. The belly tank program was full of fiascos. The excerpts are from the attached paper.

The RAF was using drop tanks long before the Americans.

 

[MIflyer]

Oh come on now! The P-6E was using drop tanks back in the 1920's! The P-40E, P-39D, and P-38E had provisions for drop tanks, not just the modified P-47, and even the early P-40B's used them! Drop tanks had been common on USAAC aircraft for over 10 years before WW2. Admittedly the ferry tanks used on aircraft such as the early P-47 had not yet adopted the vacuum pressurization system and were thus of limited value, but drop tanks were the norm rather than the exception on USAAF aircraft. Note that the RAF Mustang MkI did not roll off the production lines with provisions for drop tanks, but them again it had a 1000 mile range on internal fuel anyway - and was built to meet British requirements.

 

[Reluctant Poster]

Oh come on now! The P-6E was using drop tanks back in the 1920's! The P-40E, P-39D, and P-38E had provisions for drop tanks, not just the modified P-47, and even the early P-40B's used them! Drop tanks had been common on USAAC aircraft for over 10 years before WW2. Admittedly the ferry tanks used on aircraft such as the early P-47 had not yet adopted the vacuum pressurization system and were thus of limited value, but drop tanks were the norm rather than the exception on USAAF aircraft. Note that the RAF Mustang MkI did not roll off the production lines with provisions for drop tanks, but them again it had a 1000 mile range on internal fuel anyway - and was built to meet British requirements.

They had the capability but they weren't using them

The USAAF was slow to get drop tanks into production. They had the capability to use drop tanks but they weren't building them in anywhere near sufficient numbers until late 1943.