Merlin 70s operting at +21 and/or +25 lbs/sq in: any such luck?

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tomo pauk said:
Mike, could you please add some info about the V-1710 in P-38J/-L running at boost higher that 60 in Hg, apart from this: http://www.wwiiaircraftperformance.org/p-38/Allison_V-1710-91_ENG-57-531-267.pdf
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Hi tomo:

The following documents contain information relating to P-38's operating with engine boost greater than 60" Hg.:

Flight Tests of Fighter Aircraft with 44-1 Fuel, 16 March 1944

Project P.P.F., 4 April 1944

Attempted 7-1/2 Hr. War Emergency Rating of Allison V-1710-89 Engine as Installed in P-38J Airplane Operated on Grade 104/150 Fuel and AC 433M Spark Plugs, 22 April 1944

Project P.P.F., P-38 Series Airplanes, 25 April 1944

104/150 Fuel progress report, 29 April 1944

Project P.P.F., Installation Instructions, 29 April 1944

Preliminary Flight Tests of Fighter Aircraft Using PPF 44-1 Fuel at Increased War Emergency Ratings, 13 May 1944

Commendation of Materiel Command Personnel in Connection with the Test Program of Grade 100/150 Fuel, 29 May 1944

Flight Tests on the Lockheed P-38J Airplane, AAF NO. 43-28392 Using 44-1 Fuel, 5 July 1944

Project P.P.F. - Installation and Operating Instructions, 20 June 1944

Fuel 100/150, 9 July 1944

Grade 150 Aviation Fuel, 11 July 1944

P-38 replacement aircraft, 25 November 1944

TI 2010, Addendum 1 - Turbo Regulators for P-38 Aircraft
 
fastmongrel said:
Was +25psi the maximum any Merlin was cleared for. I find it amazing how engineers and chemists managed to take an engine from +3 (iirc) to +25 in such a short time
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Hi fastmongrel,

You might find the following to be of interest; from Alec Harvey-Bailey, The Merlin in Perspective - the combat years, Rolls-Royce Heritage Trust:





According to my calculations ("didn't seem" + "Don't think" + "seems rather" + "only about" + "I am pretty sure" + "it appears" + "were probably" + "around" + "pretty much" + "I imagine" + "likely never") + (0 citations of published sources + 0 primary source documentation) + (unfounded statements masquerading as facts + completely unsupported conclusions) = A Whole Lot of Nothing!
 
I have always wondered why the USAAF Mustangs got practically all the 150 grade juice, leaving the RAF with next to nothing, in spite the fact that at the escorting altitude of Mustangs it probably gave very little if any "extra", but it brought some maintenance issues (drastically reduced spark plug lifespan).

In the hindsight, it would have been probably better to give it the aging Mark VIII/IX that was loosing ground the latest boosted 109s/190s.
 
Mike Williams said:
Hi fastmongrel,

You might find the following to be of interest; from Alec Harvey-Bailey, The Merlin in Perspective - the combat years, Rolls-Royce Heritage Trust:
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Thanks Mike fascinating stuff. Think I might be having a look on Amazon later for that book I already have one RRheritage trust book about the Meteor engine.


Amen I hear you brother
 
I found a file, on 150 grade fuel, in our National Archives, yesterday, which ran from February to July 1944; there was an initial delay, while supplies of one of the additives were sent from the U.S. Whether they all arrived was not made clear, but, in July, concern was expressed about the inability of supply to meet demands, so an order was issued, to the effect that, in the U.K. and Mediterranean, 99/130 fuel should be used, instead of 100/130 (no idea what that meant,) and the only aircraft to which this would not apply would be carrier-borne. From this, it rather looks as though (lack of) supplies dictated usage, rather than operational requirements.
 

Thanks for that Mike, it confirms what Lew Brandon said in his memoirs. From memory, I believe 157 Sqn. were actually part of Bomber Command's 100 Group at the time, and were equipped with Mosquito XIXs, will check.
 
mhuxt said:
Thanks for that Mike, it confirms what Lew Brandon said in his memoirs.
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Yes it does!

"We were told that we would be kept on operation Diver for a while. Swift modifications were carried out to all the Mozzies. The exhaust shrouds were dispensed with, extra boost was given to the engines, we were supplied with 150 octane petrol and, of course, the noses were strengthened. With the exception of the exhaust shrouds, all these modifications were retained when we returned to our bomber support role.​
Lewis Brandon, DSO DFC*, Night Flyer, p 156. ISBN 0 907579 77 9, 1961, (Republished 1999 by Crecy Publishing)

mhuxt said:
From memory, I believe 157 Sqn. were actually part of Bomber Command's 100 Group at the time, and were equipped with Mosquito XIXs, will check.
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I checked 157's Form 541 for July 44 and the Mosquito seriel numbers recorded were NF.XIX when checked against those listed here. I was hoping you'd be around mhuxt. I am working on constructing a listing of UK based Mosquito fighter squadrons for the summer of 1944 as well as 1945 to war's end. Any help you can provide would be greatly appreciated!

tomo, various sources I have show Merlin 23 or 25 for the NF.XIX. mhuxt is the go to guy on Mosquitoes though, so maybe he'll chip in. You might be interested in these documents:





Morgan Shacklady in Spitfire, The History dedicate several paragraphs to the Spitfire VII trials using liquid oxygen and concluded that while the system was effective, it was basically a "headache" to handle and maintain.

Various Air Ministry documents in my possession refer to the Nitrous Oxide system as being used operationally in Mosquitoes. Further research on this subject is required.
 
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tomo pauk said:
Great stuff, thanks again.
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You're welcome tomo.

Here's a bit more on N2O and Mosquitoes:

From The Merlin in Perspective - the combat Years, Rolls-Royce Heritage Trust, page 27:

"Two aircraft were modified at Farnborough to provide nitrous oxide injection to boost engine power and provide an extra 40 knots plus at 28,000 ft for about six minutes. On the night of January 2/3 1944 John Cunningham, flying HK374, a modified aircraft, shot down an Me410 off Le Touquet. Fifty MkXIIIs were modified with nitrous oxide injection for 410 and 96 squadrons. Engines which had run around 200 hours with the use of nitrous oxide were found to be in excellent condition."​


Documentation of operational use of N2O in Mosquitoes, in this case a shoot down of an Me.410 by Parker-Rees Bennent of 96 Squadron:
 
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Sharp and Bowyer have much the same info, with the added note that the two squadrons receiving nitrous oxide Mossies were having the modifications done on-site during March, I believe this may have been West Malling.

157 Squadron was on the same station (Swannington) as 85 Squadron, so I assume 85 will have had the modifications for 150-octane done at the same time.

The position given in the combat report which Mike has kindly posted is, so far as I can tell, about 8 miles WSW of Boulogne-sur-Mer. The navigator's logbook apparently gave the location as a little further south, 10 miles off Le Treport. The 410 was probably from KG 51, which lost two aircraft that night. Cunningham's target on 2/3 January '44 may have been a KG 2 aircraft.

PM me about the fighter Mosquito thing Mike. I can offer up some information, but I guess it all depends on the level of detail to which you want to go, so let me know what you're trying to build and I'll see what I can do.
 
mhuxt said:
157 Squadron was on the same station (Swannington) as 85 Squadron, so I assume 85 will have had the modifications for 150-octane done at the same time.
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I can confirm that 85 Squadron converted to 150 grade fuel +25 lbs boost. Thanks for the tip!



Thanks mhuxt, good stuff! PM sent.

Here's W/Cdr. J. Cunningham's combat report of the shoot down, while utilizing Nitrous Oxide, of a Me.410 on the night of 2/3rd January, 1944, confirming The Merlin in Perspective - the combat years account:

 
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