Endurance or range of a PR Spitfire

I’ve been away for a few days, so my belated thanks for all the useful input.

During the interim I’ve discovered a little more from AP1134 The Second World War 1939-1945: Meteorology, a 1954 AHB publication.

The establishment of 1401 Met Flight was increased by two ‘F’ type Spitfires (I’m quoting) during August 1941, for deep penetration over enemy territory. The sorties were to be flown at around 30000 ft, over a total distance of no more than 1000 miles.

The increased establishment was apparently a paper one since, as I noted earlier, this first PAMPA sortie was not flown until 7 November 1941.

Because the aircraft failed to return, the flights were discontinued until a larger establishment and experienced personnel could be provided.

Wish I’d found this before asking the question, but I think it confirms your calculations, Sycamore.

Perhaps I’m reading too much into it, but the reference to experienced personnel, could be taken to imply the pilot lacked sufficient experience in navigation for such a long sortie, and departed from the planned track. At least that would explain why he ended up at Beachy Head.

I’ve l looked at the 521 Sqn ORB from the date it formed from 1401 Met Flight (1 August 1942) until October 1942. It was using Mk VD Spitfires for PAMPAs at the time, the last Spitfire PAMPA being flown by R6905 on 10 Sept. During that period most sorties were less than 3 hours, four were over 3 hours and one lasted 4 hours and 5 minutes.

Edgar

The idea that the jetstream was a new met phenomena raises its head from time to time. There are various claims as to who invented the term, and when; but ‘jetstream’ really came into popular usage after WW2, to describe a ribbon of fast-moving air at high level. The phenomena had actually been identified as early as the 1870s by meteorologists tracking elements of cirrus cloud (circa 30000 ft), so it was nothing new.

Today winds are considered to reach ‘jet’ strength when they exceed 75 mph (or it was in my day), but obviously they can reach very much greater values.

Consequently, in the case of P9550, the forecast wind of 290/80 mph was, technically a ‘jet’.

Interesting navigation exercise ;I did 3 plots,first out from BN to Magdeburg to Beachy Head,using the wind as given ,and an appx wind at 20k.ft=2/3 altitude of 270/50,cruise altitude 30k.ft and a cruise speed of 180 mph IAS/TAS 275.This gave a total flight time of 3hrs 51 min,and used appx 210 gals. fuel. Whilst the time/speed looked right, on further checking other perf.graphs,I had used a higher boost and consumption than the aircraft would be capable of,against the possible fuel capacity combinations.
So,a replot using 0 boost at a nominal 2000 rpm would give around 320 TAS at altitude with a consumption of about 36 gph..Total time would be 3hrs 20 mins,and use 136 gals,for a distance of 973 miles(st.m).
Going a bit further and taking a route from Magdeburg to Mendig then B Hd.,increased the flight time to 3hrs 26 mins.,and used 140 gals fuel.
I picked Mendig as it is between Koln and Mannheim,as it would have been probable to see the weather at both places,as it would have been able to see the Berlin area from Magdbrg assuming at 30 kft.
If the aircraft was configured with 144 gal tanks,ie 85+29+30(blister),then it was rather `tightly `planned,and as stated it ended up off B-Hd.,that is about 40 miles further West than Hawkinge,but the weather was fine….?

I dont know about the PRU Spits but once saw and entry in Dave Glasers log book when he was flying from Cumhead testing 90 gallon drop tanks he managed a flight of 5hrs and 10 minutes in a standard fully armed Spitfire.

OP gives the forecast winds as 290/80 mph which would certainly make the return very protracted, but as the pilot and his met officer almost certainly had that forecast prior to setting out it can’t explain a loss through fuel shortage.

Moggy

Not a direct answer,but from R-R Performance tests,a HurricaneII(P3269) at 30k.running at 3020 RPM,+2lbs (max) produced appx 750 hp,a consumption of appx 50 gph,and a TAS 320 mph/195mph IAS. probably about 20 mph slower than a Spitfire.
Aero Engineers like to draw all their graphs in non-dimensional units/specific this/that/hr/deg , with not too many real pilot-friendly numbers..!
edit; point by EB about jetstreams is well documented,as the Americans found over the Pacific; in any case,for planning out-and-back in any given wind ,it will always take longer than a nil-wind situation,unless one can `ride around the isobars…

There’s a good chance it was converted to Type F configuration, which would give it more fuel than a Type C. “Mk.V” in this case, as others have pointed out, just means Merlin 45 engine was fitted.

bob

In 1942, the still-air range of the Spitfire (presumably standard Mk.V) for direct flight to Malta was given as 1380 miles, with the 170-gallon overload tank.
One item, which might have a bearing, especially at height, I recently read a book by a Norwegian pilot, in which he recounts the occasional problem they had with the jetstream (though they didn’t know of its existence at the time.) He said that there were times that they flew out at an unusually high speed, then struggled to get home, sometimes arriving with minimal fuel.

The designations for early RAF PR Spitfires is confusing as the aircraft were converted before the widespread adoption of significant role designators, PR photo reconnaissance, F fighter etc. A method was devised to distinguish them from regular fighters. In all a total of seven ‘a to g’ type designations were used. The PRU designations were not changed after conversion to 40-series Merlins, unlike fighters where if a Mk I was fitted with a Merlin 45 it would be either described as a Mk V or being brought up to Mk V standard. As they were all versions of the Mk I they were also known as PRIa to PRIg. In 1941 this was rationalized so that c to g variants (the variants that were still in service at the time) became the PR III, PR IV, PR V, PR VI, and PR VII. So PR V is the same as Type E. It is believed only one Type E, N3117, was produced. It was intended as a low-altitude photo-recon with a F-24 camera in a bulged fairing on each wing. N3117 was initially modified to Type C (PR Ic) before type E. There were still anomalies. Some documents still quoted PR Spitfires with Merlin 45s as PR.V by associating them with the F.MK V

Then it was a Mk 1 that had been converted to PRV (Presumably a MkV PR version?) with a RR Merlin 45.

Anyone know the numbers for such a beast at 30,000 ft?

Moggy

Sycamore

I don’t know exactly what Mk it was (I’m obviously not an aviator) but the aircraft’s history is at http://www.spitfires.ukf.net/p009.htm (P9550). The departure airfield was Bircham Newton.

The Spitfire was with 1401 Met Flight, and this sortie was flown at around 30000 ft; forecast wind was mostly 290/80 mph.

This was actually the first PAMPA sortie attempted (so far as I’ve be able to ascertain the acronym is simply a name). That said, PAMPA sorties were mostly high-level, deep reconnaissance to ascertain cloud conditions immediately prior to a Bomber Command operation. It was not until later, when Mosquitoes were being used, that a descent was sometimes made to ascertain conditions at lower level. So far as I’m aware none of the aircraft were armed.

Both

Thank you for the distance, I’d assumed it was a little less (circa 900 miles), but was using a higher speed to estimate the time the sortie should have taken – not surprisingly my estimate was less than the planned time by quite a margin.

That’s when I realised I needed to ask the experts!

My initial thought was that the pilot had overflown Hawkinge, but there was hardly any cloud along the south coast at the time, so that’s unlikely. My thinking now is that he was south of track and was attempting a N or NW leg to reach safety. I don’t have the conditions over France, but the cloud should have been well broken.

Finally, my thanks to you both.

In these circumstance, the term “Mk.V” is a bit of a misnomer. Early PR Spitfires were based on the F Mk.I fuselage, but many (as in this case) were upgraded to Merlin Mk.45 as used in the F.Mk.V. These seem to have been recorded as Mk.Vs, but that does not mean PR Mk.Vs. It is probably because of such confusions that the PR variants were later awarded separate mark numbers within the general Spitfire series rather than in their own run.

The later Spitfires could indeed carry a variety of additional tanks under the fuselage, although these do not seem to have been commonly used in the PR world, or at least recorded on photographs! However they were not all simply ferry tanks. The smaller examples were certainly cleared for combat use, and indeed commonly seen on fighters.

When it comes to realistic missions, these would also be designed to allow for wind, which would reduce the maximum range acheivable. As (from the other thread) the AM established a series of missions requiring 500miles radius, they would not have allocated aircraft to this without a significant margin of safety, and a specified range of 1000miles would clearly not have been enough. However, we cannot rely upon that statement for a Type C as being other than approximate.

It it was flying one of these missions, then either the Type C actually had a somewhat larger range on internal fuel, or the aircraft was carrying a belly tank, or there were additional modifications made to the aircraft at Heston to increase the tankage. Or someone just got it wrong.

It is fair to point out that the PR/Met units would not require many of the diversions planned into combat missions, as they would be higher than the flak and have less need for diversions. The precise routing would depend upon the day-to-day requirements. However, a Met mission would not require to be flown all the way to the destination – under normal prevailing winds, anyway.

Absolutely direct routing to Magdeburg (starting at Marham for convenience and finishing near Eastbourne) is a shade under 1,000 statute miles.

Moggy

No so `simple` Lyffe.If you GOOGLE-Earth the route,and measure it,around 1300 st. miles/1150 nm.Just going to MDBG and back is about 920nm.(I have assumed a starting point of Benson,the home of PR,as it allowed PR aircraft to climb to altitude before crossing the Channel,and check for contrails).
It would also be useful to know the precise PR variant ,as there was only one MkV, others were `generic with lots of variations/modifications to fuel systems,weapons/or not( as the `experts will shoot me down soon enough)..
A `number `would clarify,also more info on where,when ,etc.
MkVSpitfires could carry a vaiety of combinations of extra fuel tankage, over the normal 85 gal.tanks,to give up to 285 gals of fuel,generally using external tanks,but these created drag,and should be generally called `ferry` tanks,and dumped when empty.They also restricted the aircraft`s handling to `gentle` manoeuvring.
Further,the nominal cruise speed was about 160-180 mph somewhat less at altitude,but TAS increases,so that at 30000ft it would be about 280 mph.
Depending on what power settings were used(boost and rpm) one can have
fuel consumptions from 30-60+ gals/hr.
Bear in mind also that the routes selected would also take account of known
either a/c or AA concentrations,and also `dummy`tracks.
Then,the weather would play a large part of the `plot` as well.
Lastly,Im sure that most pilots would prefer to carry extra fuel for contingencies,such as having to run,descend to low-level,deviate well away from planned route; overall a lot of pre-planning..

Moggy,

ATD Bircham Newton 1132 (I assume local time); the terminal airfield was Hawkinge, ETD 1515. The aircraft was seen to crash at 1530 between Eastbourne and Beachy Head.

Graham,

Many thanks. The history of this Spitfire (P9550) is given at http://www.spitfires.ukf.net/p009.htm

I’m thinking it might have been fuelled for a 3 hour 45 minute flight with 15 minutes additional fuel, but the tanks ran dry. I’ve not found any records of an interception by German aircraft.

There are a number of references describing the many variants of the PR Spitfire, but detailed performance tends to be given for the Type D or PR MK.IV, with the full bowser wing. The Type C or PR MK.III is likely to be the one referred to as “1000miles and external tanks will be fitted” The Type C had additional tankage of 30gall under the pilot’s seat and another 30 in the port wing with a fixed blister.

The fighter Mk.V has a cruise speed of 150mph above 15000ft. This will be IAS – Indicated Air Speed. A bowser wing variant (which I read as the study that became the Type D) is listed as having a maximum range of 1,885 miles at 25000ft at 250mph. This last speed is presumably True Ground Speed. The allowance for this is 20 gal for taxying, take-off and residue after flight, plus the required fuel in the climb. Service use might well demand additional reserves.

1000 miles at 250mph converts readily enough to 4 hours endurance, but there is clearly a number of uncertainties. On piston engines the optimum cruise speed and the optimum endurance speed are the same.

Take off from where?

Moggy

Thank you Moggy. This was actually a PAMPA sortie to ascertain cloud conditions for three targets, Berlin, Mannheim and Cologne, but obviously the flight would not have actually ‘visited’ them. The only en route point I know of is Magdeburg – which I guess would have taken less than 3 hours for a simple out and return.

I understand aircraft used for this and PR operations, were stripped of all unnecessary weight (munitions and radio) and I’m assuming fuel was restricted as well to reduce weight and improve speed. I suppose what I’m really after is the profile of an operation.

Edit. I did mean ‘4 hours’. I have the planned flight time and know the actual duration, as the Spitfire was seen to crash just off-shore after almost exactly 4 hours in the air.

There are others here who can quote some more concrete figures, but if you mean ‘just after’ four hours, rather than ‘four hours fifty minutes’ then I doubt many would set off on a planned flight of 3.75 hours with just a 6% reserve.

Range can generally be extended by throttling back, but if there is a bandit on your tail anyone would take the postponed risk of falling out of the sky for lack of fuel later, rather than being shot down immediately.

Moggy