Author Topic: RAF 150 octane (Read 11404 times)

Crumpp · « **Reply #45 on:** September 24, 2005, 12:21:44 AM »

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Also I will point out that combat fighters were not built to last

Your correct, they were not built to last. However with missions lasting 4-6 hours that means every week your checking motors. Fight hours add up quickly with the long duration flights.

For example.

If only a quarter need to be replaced a week that is still 100 percent replacement a month. This is in addition to normal wear and tear.

That is a large number of motors needed just to maintain the current force and does not include all the new production.

Add in the fact too that the fuel robbed the performance of the aircraft by lowering compression and it is no wonder "enthusiasm waned quickly".
We are not talking about a modification that gave the Mustangs better performance, you know?

If the allies had been desperate, like the Germans in their decision to field the Me262, it would make sense. However they were not, the war was clearly won by this point. Individually their aircraft were very competitive with the Luftwaffe's and they had overwhelming numerical superiority.

All the best,

Crumpp

Neil Stirling1 · « **Reply #46 on:** September 24, 2005, 03:48:02 AM »

Again British experience with 150 grade. September 1944.

Neil

Angus · « **Reply #47 on:** September 24, 2005, 04:46:13 AM »

Well, they sure seem to have tested it, - successfully

MiloMorai · « **Reply #48 on:** September 24, 2005, 05:11:03 AM »

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Originally posted by Crumpp
Add in the fact too that the fuel robbed the performance of the aircraft by lowering compression and it is no wonder "enthusiasm waned quickly".

Lowering compression? The CR for the Merlin stayed at 6:1 for what ever boost was used.

Crumpp · « **Reply #49 on:** September 24, 2005, 08:53:14 AM »

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Lowering compression? The CR for the Merlin stayed at 6:1 for what ever boost was used

That is what happens when the valve seats wear.

Those are trials. They are recommendations and the fuel was adopted by the 2nd TAF. Remember, the fuel was successful for short duration flights. High speed operation short duration flights were characteristic of Operation Diver.

Long range cruising profiles characteristics of missions over Europe on the fuel caused the problems. Lead fouling was the problem this fuel was causing, which also robs power, BTW. It shorts out the plugs. That's why they would lose the ability to use (+25) boost. Without all cylinders firing the motor could not achieve the pressure.

PEP was added to prevent the lead fouling. It caused even worse problems.

Look guys, I am not claiming that it was not used nor that the allies did not try to adopt it.

What I am saying is that it does not appear it was "the predominate" fuel for any large period of time due to the technical difficulties.

All the best,

Crumpp

Squire · « **Reply #50 on:** September 24, 2005, 09:10:45 AM »

"We are not talking about a modification that gave the Mustangs better performance, you know?"

You have lost me there Crumpp, how do you figure they ran at a higher Hg but got no performance increase? Thats the whole point of using the fuel.

You know, I was thinking, there must be a gazillion Mustang experts on the BBSs, seems 50 percent of the players only research the P-51, you would think this Q. would have been settled by now re 8th AF FC use of the stuff a long time ago...

Neil Stirling1 · « **Reply #51 on:** September 24, 2005, 10:00:51 AM »

Crump you claimed this,

According to Dr Brett Stolle of the USAF Museum, only aircraft that consistanly ran 150 grade fuel were those involved in "Operation Diver" and in some cases "Operation Crossbow".

This is demonstrably not the case.

Where did you get your information on valve seat wear from?

Can you prove that Mossi V1 missions were short?

Mitchell's, Boston's and Mosquitos were not short range aircraft.

Neil

Crumpp · « **Reply #52 on:** September 24, 2005, 10:05:54 AM »

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You know, I was thinking, there must be a gazillion Mustang experts on the BBSs, seems 50 percent of the players only research the P-51, you would think this Q. would have been settled by now re 8th AF FC use of the stuff a long time ago...

Problem is I don't think there is a clear answer among the Historians much less the amatuers.

The only units I have found that one can point a finger too and say beyond a shadow of a doubt the fuel was used consistantly, is the Operation Diver units. Those units belonged to the 2nd TAF.

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You have lost me there Crumpp, how do you figure they ran at a higher Hg but got no performance increase? Thats the whole point of using the fuel.

First of all, this is not something "Crumpp" is coming up with. It is directly stated.

The fuel caused two problems both of which rob power from a motor:

1. Spark Plug fouling causes the plugs to short. This is why the motor backfires from intermittent ignition firing. If the motor is flown for longer than 15 minutes at cruise settings, the fouling can completely shut down a cylinder according to the RAF.

From Roger Freemans Mighty 8th War Manual:

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Despite reservations in some quarters, all 8th AF fighter groups went over to 100/150 fuel between July and late September 1944. Attempts to reduce plug fouling by decreasing valve setting and adjustment of carburettor enrichment valves did not appear to help matters. During the autumn there was an alarming increase in the number of P-51 take-off crashes due to engine failure, mostly attributed to the use of the 'Purple Passion' fuel.

2. When PEP was added to prevent fouling, it attacked the valve seats causing a loss of compression.

From Roger Freemans Mighty 8th War Manual:

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Opinions differed but the most likely reason was thought to be valve seat inserts burning out leading to diminishing valve clearance and loss of power. Enthusiasm for the new fuel waned quickly and in the same month some units requested a return to 100/130.

All the Best,

Crumpp

Neil Stirling1 · « **Reply #53 on:** September 24, 2005, 10:31:47 AM »

Lot fuel to use on operation Crossbow

Neil

Crumpp · « **Reply #54 on:** September 24, 2005, 10:32:19 AM »

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According to Dr Brett Stolle of the USAF Museum, only aircraft that consistanly ran 150 grade fuel were those involved in "Operation Diver" and in some cases "Operation Crossbow".

Are you saying I am lying Neil?

We have seen that document before. I have a copy of it.

Supply is not the problem in this case, Neil. Technical difficulties are the cause.

All the best,

Crumpp

MiloMorai · « **Reply #55 on:** September 24, 2005, 10:32:50 AM »

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The only units I have found that one can point a finger too and say beyond a shadow of a doubt the fuel was used consistantly, is the Operation Diver units. Those units belonged to the 2nd TAF.

What units were these?

Neil Stirling1 · « **Reply #56 on:** September 24, 2005, 11:08:16 AM »

Crump there were technical difficulties, some aircraft types affected more than others.

We have a fist hand British report on short range and long range aircraft that states this,

You have a second hand account as reported by R Freeman into american aircraft and apply it to British aircraft, why?

Mk XVI Spits did suffer, but as you know these aircraft had an American engine.

Neil.

Crumpp · « **Reply #57 on:** September 24, 2005, 11:16:20 AM »

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What units were these?

306 Squadron, Mustang

157 Squadrons Mosquito

For sure were in Operation Diver. RAF squadron histories are proving tough to track down. Every one that I have been able to track down has been in the 2nd TAF. Those units above participated in Diver.

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Can you prove that Mossi V1 missions were short?

Certainly they were short range when compared to the daylight bombing escort missions.

That is the same document Neil, correct? It is the result of the trials not an order putting it into service with the 8th USAAF.

We know it was placed into service. You don't have to prove:

1. There was ample supply - Sure there was, supply was not the problem.
That is not the issue. The issue is how widespread was it's use.

2. It was ordered into service - We already know it was ordered into service.

What is in question is just how common and for how long?

The fuel robbed performance. Something no fighter pilot would accept gracefully.

You still have not answered my question about Dr Stolle. Are you saying that I am lying?

All the best,

Crumpp

Neil Stirling1 · « **Reply #58 on:** September 24, 2005, 11:36:49 AM »

I asked him where your quote came from. He replied with this.

"I do not remember that inquiry about Operation Diver. If you are in contact with Crump ask him the date of my letter/email of reply. It will help me find out what sources I used. As I do not recall the inquiry it is likely the information credited to me was snipped by me from some other source/report. I handle thousands of inquiries yearly and this one does not appear to be in my saved file."

Not very convincing is it ?

"Certainly they were short range when compared to the daylight bombing escort missions."

Not proof but a statement of opinion.

Neil

MiloMorai · « **Reply #59 on:** September 24, 2005, 11:45:56 AM »

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Originally posted by Crumpp
306 Squadron, Mustang

96 Squadron, Mosquito

85 Squadron, Mosquito

157 Squadrons Mosquito

306 Squadron, Mustang - a 2TAF unit - Mustang III

96 Squadron, Mosquito - an ADGB unit - Mk XIII

85 Squadron, Mosquito - a BC unit - Mk XIX

157 Squadrons, Mosquito - a BC unit - Mk XVII

So only one of the units you claimed as 2TAF was really a 2TAF unit.

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The only units I have found that one can point a finger too and say beyond a shadow of a doubt the fuel was used consistantly, is the Operation Diver units. Those units belonged to the 2nd TAF.