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Never enough range

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Never enough range

Old 29th Apr 2013, 21:56
  #41 (permalink)  
 
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Originally Posted by ian16th
Rather than why not replace a Merlin with a Griffon in the P-51, why not replace the Allison's with Merlin's in the P-38?

After all, the P-51 experience had shown that it worked!
This was proposed, but the Allison-powered P-51 had no turbo-supercharger, which is why the Merlin improved its mid-high-altitude performance,.

The P-38 had turbo-superchargers for its Allisons, which gave excellent high-altitude performance. Thus, any gains would be much smaller, and as the change-over would cause a significant disruption on production rate, the idea was dropped.

This article has a discussion of the proposal, phrased in terms of the benefits... but glossing over the problems (it only discusses performance to 30,000 feet).
The P-38 Lightning
In 1940 Packard Motors of Detroit began building the two-speed Merlin V-1650-1 (Merlin 28) under license from Rolls Royce. This engine had 1170 horsepower in high blower with a critical altitude of 21,000 feet. Lockheed ran a study comparing a Merlin XX powered Lightning with a standard V-1710 powered variant. The reported speed difference was over 25 mph, favoring the Merlin powered airplane. Climb performance was similar to the Allison powered machine.

Another Merlin vs. Allison comparison in 1942 involved the V-1710-89/91 Allisons (engines used in standard P-38J) and the Packard V-1650-3 two-speed, two-stage Merlin used in the P-51B/C. Utilizing Military Power speed was almost identical.

Yet another study in 1944 compared V-1710s producing 1725 bhp and "advanced" Merlins using "special" fuel and producing 2000 bhp (no altitude specified). The Merlin powered version could supposedly attain 468 mph at 30,000 feet, which was considerably better than the Allison powered version.

These studies were all conducted by Lockheed and exhibit a certain amount of optimism in regard to maximum speed for both types, but the consensus clearly shows better performance with the Merlin powered Lightning.
Note however, that the same article earlier says that the factory-set maximum manifold pressure ratings for the Allison engines were rarely followed by front-line units. They used significantly-higher manifold pressure settings (up to 60" vs the factory 40"-45"!

As a result, combat units regularly achieved higher climb rates and maximum speeds than the factory did. Thus the above Lockheed factory comparison short-changes the performance the Allison was capable of.



This article mentions one of the areas where performance would have dropped with the Merlin (it discusses performance above 30,000 feet):
Whatever Happened To The P-38K ?
There were some performance areas that would suffer. While a gain in speed at medium altitudes was expected, the rate of climb would be reduced by as much as 400 feet per minute. Service ceiling would also be reduced as the Packard Merlin XX made considerably less power above 30,000 feet than did the Allison V1710.

Last edited by GreenKnight121; 29th Apr 2013 at 21:57.
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Old 29th Apr 2013, 23:38
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why not replace the Allison's with Merlin's in the P-38?
Lockheed themselves looked at such a conversion at one point. Nevertheless, a P-38 was sent to Rolls Royce at Hucknall for a trial installation of Merlin XX engines. The program was initiated by the Americans as the P-38 was proving somewhat troublesome in the high altitude role over Europe. RR made a number of test flights in the unmodified state, but before conversion started an order came from Washington for the aircraft to be returned to the 8th Air Force immediately. The supposition is that, Allison having seen their P-51 business go up in smoke, were somewhat upset to see their P-38 business possibly following a similar fate, and applied the necessary political pressure.
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Old 30th Apr 2013, 14:25
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FED

Never a problem with the Valiant
In the very early days of AAR, when we on 214 were doing the trials. Most of out tanking was done between our own Valiant's. Often fuel was passed from A/C 'A' to A/C 'B' and then A/C 'B' passed fuel to A/C 'A'. This was done several times.

When we started doing the night time transfers, and it was getting close to the bars closing, an A/C that had just passed fuel would often develop a snag that required it returning to base, leaving the recently topped up A/C to burn or ditch fuel so that it could land.
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Old 30th Apr 2013, 15:47
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Jettisoning was sometimes very deliberate. Should an underwing tank pump fail and a receiver was short one could jettison and pass fuel at the same time.
The good tank pump would deliver at about 2,500 lbs a minute and the other tank would take three minutes to empty. As soon a big aircraft engaged it would be fed with fuel from one underwing and the fuel from the other would be jettisoned. The ailerons were powerful enough to take up to 6,000lbs imbalance and you could always jettison in stages.
Spectacular, and quite alarming, when you first did it on the receiving end.
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Old 30th Apr 2013, 16:21
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We once found our aircraft which had been fuelled for a transit to Leuchars (c 40,000 lb) was u/s. My flight commander captain got us all to jump into the combat-readied Dragonfly aircraft which had 86,000 lb on board and as he was not willing to wait for it to be defuelled we set off in that. As soon as we coasted out over Blakeney I started to jettison through the pods which we continued to do all the way up to top of descent for Leuchars. This was in 1973/74 when as I recall we were talking about petrol rationing and they had just introduced the 50mph speed limit on all roads to save fuel!
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Old 30th Apr 2013, 16:38
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Should an underwing tank pump fail and a receiver was short one could jettison and pass fuel at the same time.
Sounds like some mornings after a good Pub Crawl and late night Curry!
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Old 30th Apr 2013, 21:11
  #47 (permalink)  
 
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Oh, SASless. So terribly inapropriate in a public forum. But wonderfully funny.

I do not thank you for the picture you've planted in my head!
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Old 30th Apr 2013, 23:22
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There were good long-range fighters in WW2 - and then came jets. We just about had the technology worked out for better jets and supersonics came along, the only way to get decent range in a supersonic being apparently through sheer size, cf Avro Arrow.

Today if you must have supersonic speed (there is a strong case for subsonic ground-pounders - if they'd done the A-6F Intruder II we'd be SLEPping the hell out of them and fitting them with AESA) your best bet is to arrange to carry a lot of external fuel. Today's range champs are the Rafale and Strike Eagle.

Last edited by LowObservable; 30th Apr 2013 at 23:26.
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Old 1st May 2013, 13:39
  #49 (permalink)  
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"There were good long-range fighters in WW2"

At the end yes, but not at the start of WW2

Hell, there were hardly any decent long-range BOMBERS at the start of the war
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Old 26th Dec 2013, 05:21
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Haraka, just a follow up on the Ed Schmued being ex Messerschmitt story.

Rolls Royce test pilot Ron Harker test flew the Mustang I on April 30, 1942 and praised the aircraft, suggesting fitment of the Merlin, and commented that he thought it looked like a Bf 109F "probably due to it being designed by one of the Messerschmitt designers, who is now with North American."

The above comes from page 10, "Rolls Royce and the Mustang" by David Birch, Derby, England: Rolls Royce Heritage Trust, 1987.

Could it be that the design credit comment was a tongue in cheek throw away line mistakenly taken as serious by a reporter in attendance and so appearing in "Flight"?

Mustangs of the 357th Fighter Group at one stage sported white spinner and nose and broad white stripe on the fin/rudder so as not to be mistaken for a Messerschmitt.
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Old 26th Dec 2013, 08:02
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Too much fuel

I launched from a ship and took 6000 lbs of fuel off a Victor tanker over the English Channel once. Due to fog over the whole UK it turned out the tanker and I were the only folk airborne that day, and when I was summonsed back to Mum due lack of trade, the tanker crew asked if I could take some more fuel because they had a command directive not to dump anything. When I asked how much they wanted me to take they said "about 100K lbs please!" Couldn't help them, so I asked what they were going to do. Their reply was, "We're thinking of doing a practice diversion to JFK." Quite sure they had too much fuel that day...
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Old 26th Dec 2013, 11:42
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To come back to th OP's question, the only long range fighter involved in the Battle of Britain (Bf110) was severely compromised, relative to our short range opposition. On the other hand the Me 163 had a powered endurance of about four minutes...which for its mission was plenty, although it was very unsatisfactory for other reasons!
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Old 26th Dec 2013, 12:20
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Leon,

24 Sep 1987 - A Tornado F3, ZE155, from Boscombe Down, made the first non-stop un-refuelled crossing of the Atlantic by a British jet fighter. The sortie covered 2,200nms in 4 hr 45 min, and took place as the aircraft returned from Arizona after a series of tropical trials.
Can you be sure? In 1982 Buccaneers (the last British-built jet fighter/bomber) from 16 Sqn deployed to Nellis and flew unrefuelled across the Atlantic from the Azores to Gander (Great Circle route but against the prevailing wind). Buccaneers (RN/RAF) from as early as the 60s routinely flew across the Atlantic unrefuelled from Gander or Goose to Lossiemouth (with the jet stream, which one presumes the F3 took advantage of too)!

On another point, can the Tornado (F3 or not) really be called a British jet aircraft as the F3 was designed from the GR1, not all of which was designed and built in Britain!? Although I take your point that it was in BritMil service and was a fighter (or was it actually an interceptor!).

Anyway, the real point and answer to the original post:

My question is firstly WHY? and secondly has there ever been a war plane built with TOO MUCH range??
is this: Range is inconsequential to a warplane, it is Radius of Action that is imperative AND radius of action in its designed role. A Buccaneer, for example, had a high level range of 2300nm if you fitted every possible tank and filled them to the gunwales - you could (I was involved in planning it once) fly a Buccaneer round the World without AAR as long as you selected judicious landing fields and appropriate diversions! However, the radius of action in its war fit at low level in Germany was no more than 300nms - sufficient to attack enemy airfields and opposing forces during the Cold War and return to base to do it all again (assuming that you got through the SA-2 belt at your first attempt!).

So for Range read RoA!

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Old 26th Dec 2013, 15:17
  #54 (permalink)  

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HH's point is an interesting one. Several good reasons have been given why many original specs were like they were and I cannot see a manufacturer deliberately exceeding the required spec as this would create problems with other aspects of the design.

The Harrier GR1 spec of the mid 60s was interesting in that it called for a 2000nm unrefuelled ferry range (rather more than the range of Trident airliners of the day). We met the spec by unscrewing the small wing tips that were outboard of the outrigger wheeels and replacing them with slightly larger so called 'ferry tips'. This took about 45 minutes but I don't ever recall the RAF using this capability.

When I wandered about in the Dunsfold demonstrator G-VTOL (particularly all over South America for example) we were always airborne on our own and often unable to contact our destination until well on the way. So I never planned a leg longer that 1000-1200 miles to keep stacks in hand for whatever. On occasion this caused real aggro at our destination as I always refused to demo on arrival having so much fuel and a congfiguration that reduced the max g . This did not go down well with Generals and salesmen alike.

Hey ho.
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Old 26th Dec 2013, 15:43
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I don't remember ever thinking, "God, I wish I had less fuel."

Not even on a JMC?
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Old 26th Dec 2013, 16:32
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Charles Lindbergh

Anyone interested in long range ops in WW2 should read of Charles Lindbergh's efforts as a P38 test pilot in the Pacific. Lindbergh taught the pilots techniques that added 500mms to the range of the P38. His wing kept pitching up in places the Japanese never expected
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Old 26th Dec 2013, 16:58
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I seem to remember many years ago hearing that, when the Tornado was being designed, the German partners considered it politically unacceptable for a Tornado to reach the Russian border at low level from bases in West Germany (don't forget there was a West and East Germany in those days). Targets in East Germany and Poland fine, but no further. I believe that when the Tornado replaced the Buccaneer in RAFG that some of the Bucc's targets had to be handed over to F-111's, as the Tornado didn't have the range to cover them.


Could be an urban myth I suppose...
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Old 26th Dec 2013, 17:13
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Tornado GR1 Range

It is indeed true that it was deemed politically unacceptable at the design stage for the Tornado GR1 to have the range to reach the USSR. I remember this being mentioned by a VSO who accompanied a Staff College visit to my sqn in the 1980s.

It is also true that the Tornado GR1 range in the strike role was less than the Buccaneer. Some Tornado missions were planned to be buddy-buddy refuelled from Buccaneers.
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Old 26th Dec 2013, 17:26
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F111

I seem to remember being told that the F111 was not based in Germany because it would then have round trip fuel for Moscow and would therefore have to be counted in the SALT talks.
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Old 26th Dec 2013, 19:06
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F/O Bloggs

The info came from the RAF History webpage under 1987 - RAF - RAF Timeline 1980 -1989

My suggestion is to dig out log-books and the old F540s and/or write to the Air Historical Branch! That way you can rewrite the history books.

LJ
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