BoB after: how would you like to see Spitfire further developed?

About the only thing was feasible do to make it an offensive weapon that was needed after after BOB was add range so it could go after the LW rather then being a clay pigeon for same . The LW could pick and choose when to fight and they did with great effect so unless some one has an idea to substanially increase the range by 2 or 3 times you are beating a dead horse . My little Toyota can actuallty go further on tank of fuel then the Spit

Shortround6 said:

The "laminar" flow didn't really do a lot for drag on it's own. What it did do was allow more interior volume for the same drag. Most WW II laminar flow wings only held the low drag airflow another 5-10% of the airfoil over a normal wing. In other words don't expect much of a change in performance over a normal Spitfire but you could wind up with more volume in the wings for fuel tanks.

Click to expand...

I see P-51 as a way faster plane, on same engine power, when compared with other planes with in-line engines about same shape size. The major difference was the laminar flow wing.
Anyway, even if the difference is cut at half between historical Spit IX Merlin Mustang, the effort would be worth it.
Good point about the increased internal volume.

The increased fuel tankage increases usability even more for Asi/Pacific MTO; Spitfire flying over Japanese bases would've presented a major threat.

tomo pauk said:

I see P-51 as a way faster plane, on same engine power, when compared with other planes with in-line engines about same shape size. The major difference was the laminar flow wing.
Anyway, even if the difference is cut at half between historical Spit IX Merlin Mustang, the effort would be worth it.
Good point about the increased internal volume.

The increased fuel tankage increases usability even more for Asi/Pacific MTO; Spitfire flying over Japanese bases would've presented a major threat.

Click to expand...

"Way faster" is about 20-30mph.

But it wasn't all down to the wing.

The Spitfire radiators were designed to use the Meredith effect, but Joe Smith admitted that the radiator intakes and exits weren't sized properly, especially the exits.

You may point to the Spiteful, with its laminar flow wing, being some 35-40mph faster than the Spitfire XIV on which it was originally based. However, the Spiteful also had a new design radiator system, similar to the system used on the Bf109.

I would say that tidying up the radiator installation would be quicker, cheaper and available earlier than the laminar flow wing. It may not make all the difference in top speed between the Spitfire and the Mustang, but it would close the gap and still maintain thehandling for which the Spitfire was famous.

Simple, produce the Mk III!


It was a notable refinement over the original Spitfire design. The performance improvement was much like the Bf-109E progressing to the F. Unfortunately, the RAF and Air Ministry decided to go for the Mk V, as the Merlin XX had already been earmarked for the Hurricane and switching over to the much-changed Mk III would have disrupted production just as it was looking to expand Fighter Command.


Improvements over the Mk I/II:

More engine power, available at higher altitudes:

Two speed, single stage Merlin XX replaces single speed, single stage Merlin II/XII. Early Merlin XXs had 1240 hp, pushing the Mk III to 385 mph. Later the Merlin XX was cleared for 1390 hp, pushing the Mk III up to 400 mph (in concert with some with other detail improvements, although I believe no cannon were fitted for the test flight)

Reworked landing gear:

Strengthened and raked forward, improving both ease of control during landing and stability on the ground. Would have made the Spitfire a better carrier aircraft. The wheels were also completely covered by fairings to reduce drag.

Adoption of a clipped 'C' type universal wing:

Slightly strengthened wing with a seven foot reduction in wingspan to increase rate of roll. C type wing had double the ammunition capacity for the Hispano than the B type wing (120 rpg). Wing area reduced from 242 sq ft to 220 sq ft.
Ailerons were shortened slightly to improve rate of roll, particularly at higher speeds

Increased fuel capacity:

95 imp gal nose tanks as opposed to 85 imp gal nose tanks on the Mk V. Even with the higher fuel consumption of the more powerful Merlin XX, ranges would have been about the same as for Mk I/II (550-520 miles, as opposed to 450-480 miles for the Mk V).

Other improvements:
Retractable tail wheel
Internal bulletproof windscreen with new panel arrangement
Reinforced engine mounts
Deeper radiator with a new boundary layer splitter and a larger oil cooler (still asymmetrical Mk V style though)
Reworking of some skinning


If the Mk III was produced, you'd see a Spitfire that was marginally slower in the climb (300-450 ft/sec) and marginally slower (1-2 mph only) than the Mk V under about 10,000 ft. Its rate of turn was also inferior to the Mk V.

However, the aircraft was much faster above 16,000 ft, better in the rolling plane, faster in a dive (both acceleration and limiting speed), easier to handle on the ground and had better control harmonisation.

At 385 mph, the MK III was notably quicker at best altitudes than the Mk V and wouldn't be so badly outclassed against the Bf-109F2/4 at high altitudes and the Fw-190A2/3/4 at medium altitudes.

With a bit more fuel, its also got around 10-15% better range. Which is not much, but every little bit counts.



To go a little further, beyond what was historically done with the Mk III:

Over 1941:

Introduce metal skin ailerons;
Add Mk VII/VIII style wing tanks, taking internal fuel all the way up to 123 gallons. Range then goes up to about 750-800 miles, enough to reach well into France, almost to the German border
Plumb the Mk III for drop tanks, particularly US/German style 'teardrop' tanks. Start with the 32/35 imp gal Hurricane external tanks and then add 45, 65 and 90 imp gal sizes through the year.

Fit the larger Rotol 4 blade propellers to better take the power of the Mk XX
Fit multi-stub exhausts, replacing the older fishtail exhausts
Improve the design of ammunition feed and the heating for the Hispano (done in the later Mk Vc)

With the detail improvements and higher boost clearance for the Merlin XX, the Mk III would be a 400 mph capable fighter.


Over 1942

Refine oil cooler and radiator design (a la Spiteful) to reduce drag
More improvements to aircraft skinning, particularly improved surface finish and introduction of sunk rivets (as seen on the Mk VIII/Mk XII)
Fit Bendix 'anti-g' carburettor


NOTE: With 123 gal internal and up to 90 gal external, the Spitfire becomes a fighter capable of 5 to 6-hour escorts. RAF Mk VIIs in Europe did five-hour escorts to La Pallice in France (round trip of over 1000 miles), and RAF Mk VIIIs in the Pacific did one six-hour 1250 mile round trip (with 90 gal external tanks).

With a 90 gal external tank, still air cruising range for the Mk VIII was 1180-1280 miles at 220 mph, depending on the exact engine and altitude of cruise.

Rule of thumb is that combat radius is about 30-40% of cruising range (depending on flight profile). This gives an 'improved Mk III' a combat radius of anywhere from 355-500 miles. At 35% of best range, this is just under 450 miles.

This range is sufficient to put Spitfires over the Rhur, Stuttgart and Frankfurt with 15 minutes at combat power and 5 minutes at WEP. Although this is still short of Berlin. I wonder how the Luftwaffe would have reacted to escorted RAF raids over Germany in mid-late 1941?

tomo pauk said:

I see P-51 as a way faster plane, on same engine power, when compared with other planes with in-line engines about same shape size. The major difference was the laminar flow wing.
Anyway, even if the difference is cut at half between historical Spit IX Merlin Mustang, the effort would be worth it.
Good point about the increased internal volume.

Click to expand...

People are still arguing over wither it was the wing or the better radiator installation on the P-51. or perhaps a bit of both. don't forget that even a few small details can add up to a big difference. The famous 6mph speed difference for the bullet proof wind screen for the Spitfire comes to mind. and that is at 360mph or so, at 420mph the same change in drag is good for over 8mph. Throw in 2 or 3 other little differences and it becomes impossible to attribute the speed difference to any one thing.

Bubble canopy, asap. (which means larger pointed stabilizer asap as well)
Negative G carburator.
Automation of throttle, pitch, mixture.
2 x 20mm (belt fed, no 60 rd drum!) and 2 x .50 brownings, asap, instead of the 2 x 20mm and 4 x .303s. 4 x 20mm would have been nice, but then you gotta make a different wing, big hassle. sigh.

Add a bit of fuel, get a proper drop tank.

Those are the simple things. Bigger projects would be moving the radiator to the mid/rear fuselage area (which was considered during initial development) and redesigning the wing for wide landing gear and better mounting of 4 cannons, ie a Spiteful wing (as noted earlier).

It would be hard to do anything to the Spit. It was a near perfect defensive / interceptor. The only real combat deficit it had was range, and to get that you end up with a whole new airplane, the Spiteful. I would say keep making the traditional Spitfire for home defense, and then also make the Spiteful or license built Mustang for offense.

tomo pauk said:

The main near time improvement could've been the installation of Merlin XX.
The long term change might include the development of the new wing, that would feature a wide track gear, tailored for 4 cannons per plane. Some fuel tanks in wings, too. In case the wing is of laminar type, the speed on two-stage Merlin should be akin to P-51s, with better climb. The teardrop canopy would've improved the visibility, as it did in other fighters of the era. The Griffon installation should proceed as historically.

Click to expand...

IMHO the wider track u/c was not essential and would have needed completely new wing, so not worth of effort in those rather desperate times, C-wing incl the rake of the u/c wheels 2 ins forward to improve the ground stability and the possibility of 4 20mm cannon armament, not often used because of the weight penalty. The Mk VII/VIII type fuel system would have improved range issue considerably, so at least a short term solution.

Juha

Hi, wuzak, SR6

Thanks for pointing out about the Meredith effect, I was told on this forum before that Spit used the effect historically. Apparently not as good as P-51, though. Maybe installing the radiators in the aft hull would nicely balanced out the ever heavier engines that were to be installed from 1941 on, anyway better than my idea of mounting them on wing leading edges.
As for Spiteful being faster than similarly engined Spit, apart from having laminar wing more streamlined radiators, it also had smaller wing area (not very good idea?).

Hi, Juha,
My idea about the new wing is for long term modification, entering the production some time in 1942. The supposedly narrow track of the U/C was not something that Spit was often blamed for?IMO even with 4 x 20mm the Spit would be far better climber than P-51 (not that 2 cannons + 2 HMGs wouldn't suffice to get the job done).

The problem with major revisions is the interruption in production as Juha has said. Look at all the minor revisions that were put off, never done or delayed because of the fear of interrupted production. Other modifications depend on other developments. The Spitfires with 60 drums carried them because, at the time, there was no "working" belt feed. Once there was a working, reliable (somewhat) belt feed the Spitfire got it but there was little that the Spitfire designers/factories could do about it.
Even the Substitution of the of the MK IX for the MK VII was done for the reason of keeping production line changes to a minimum. Now this could very well have been a mistake but very large changes (entirely new wings and/or fuselages) is probably beyond what was practical. You also seldom, if ever, get something for nothing. Changing the wing may get more speed or more volume for fuel but it may also (almost certainly) change the stall characteristics and handling. What do you want to give up for what you get?

The Mk IV (prototype Griffon engined Spitfire) first flew in 1941, IIRC. That lead to limited production of the Mk XII (basically the Mk V airframe with a Griffon engine) of 100 units.

The definitive version of the Griffon Spitfire was to be the Mk XX. A new, stronger wing design (not laminar flow) was to be used in the XX, but this didn't see production until late 1944/early 1945 in the Mk 21. Even then there were serious balance issues hat took time to sort out.

I can't see a laminar flow wing being around at a time which would make it useful to the war effort.

tomo pauk said:

Hi, wuzak, SR6

Thanks for pointing out about the Meredith effect, I was told on this forum before that Spit used the effect historically. Apparently not as good as P-51, though. Maybe installing the radiators in the aft hull would nicely balanced out the ever heavier engines that were to be installed from 1941 on, anyway better than my idea of mounting them on wing leading edges.
As for Spiteful being faster than similarly engined Spit, apart from having laminar wing more streamlined radiators, it also had smaller wing area (not very good idea?).

Click to expand...

Just plonking the radiator in the fuselage doesn't guarantee that it will work. The Tornado prototype was originally fitted with a mid/rear fuselage mounted radiator (much like the Hurricane, in fact) but this didn't work very well, and the radiator was moved to the chin position, remaining there for the Typhoon and production Tempest Vs.

The Tempest I with leading edge radiators was some 20mph faster than the more powerful (by 100hp or so) Tempest II, and a little more than that against the Tempest V with the chin radiator.

I am glad that the Spitfire didn't get the belly scoop radiator - it would hav eruined the looks.

I do wonder what the effect of Bf109/Spiteful type radiators (lowline, trailing edge) would have been on a Mk VIII or XIV.

We have been over this before too. One doesn't just say "I will use the Meredith effect" and presto get a given level of drag reduction or actual positive thrust any more than one can say "I will just use an XX supercharger and get the power I want".

The Merideth effect is essentially building a sort of ramjet engine using the heat given off by the radiator (or engine it self in an air cooled engine) to heat the incoming air instead of burning fuel in a combustion chamber in the ramjet duct and then ejecting the heated air out the rear of the duct at a higher speed than it came in. All while keeping the air flow drag going through the duct and radiator matrix (or engine cooling fins) to a minimum. It took a while to really get it "right" and some designs did work better than others as some had several more years of laboratory work to go one or had more volume to put the ducts in.

tomo pauk said:

Hi, Juha,
My idea about the new wing is for long term modification, entering the production some time in 1942. The supposedly narrow track of the U/C was not something that Spit was often blamed for?IMO even with 4 x 20mm the Spit would be far better climber than P-51 (not that 2 cannons + 2 HMGs wouldn't suffice to get the job done).

Click to expand...

In the few pilot memoirs I have read, I cannot remember much criticism of Spitfire's landing characteristics or the t/o characteristics of the Merlin powered versions, the Griffon versions were a bit different animals and needed more careful handling in t/os because of the powerful torgue and the opposite turning of the airscrew. The geometry of Spits u/c was different of that of Bf 109 and Spit was lighter tailed so less inclined to ground loop. Downside was of course that in conjuction of clearly smaller ground clearance of airscrew tips it was much easier in Spit to get airscrew tips to hit ground by braking hard than in Bf 109.

Juha

Shortround6 said:

The problem with major revisions is the interruption in production as Juha has said. Look at all the minor revisions that were put off, never done or delayed because of the fear of interrupted production. Other modifications depend on other developments. The Spitfires with 60 drums carried them because, at the time, there was no "working" belt feed. Once there was a working, reliable (somewhat) belt feed the Spitfire got it but there was little that the Spitfire designers/factories could do about it.
Even the Substitution of the of the MK IX for the MK VII was done for the reason of keeping production line changes to a minimum. Now this could very well have been a mistake but very large changes (entirely new wings and/or fuselages) is probably beyond what was practical. You also seldom, if ever, get something for nothing. Changing the wing may get more speed or more volume for fuel but it may also (almost certainly) change the stall characteristics and handling. What do you want to give up for what you get?

Click to expand...

I agree that having plenty of good planes seemed like a better bet than having smaller number of excellent ones. It has to do about at what part of the war one takes the bet. I entirely agree that neglecting of Mk. VIII vs. Mk.IX was not a very good thing, and killing Mk.III was also a mistake IMO. Further, having cr@pload of P-40s or Spit Vs in 1944 just puts trained personnel in jeopardy, since the planes are just one part of any air force.
Hence I've asked specifically about two levels of the upgrade, one (minor) to take effect in 1941, other (major) maybe in early 1943. The people at RAF or/and Supermarine were dissatisfied with Spit's wing, for example, and were to introduce a revised wing in Mk.XIV, and a new one for Spiteful. I see no problems to have a new wing in 1943 with design work starting in early 1941.
We could take a look at Hawker - from Typhoon, it took them 2 years to developed a completely new wing for Tempest.
As for what I want to give, I'll give the low speed handling.

Shortround6 said:

We have been over this before too. One doesn't just say "I will use the Meredith effect" and presto get a given level of drag reduction or actual positive thrust any more than one can say "I will just use an XX supercharger and get the power I want".

The Merideth effect is essentially building a sort of ramjet engine using the heat given off by the radiator (or engine it self in an air cooled engine) to heat the incoming air instead of burning fuel in a combustion chamber in the ramjet duct and then ejecting the heated air out the rear of the duct at a higher speed than it came in. All while keeping the air flow drag going through the duct and radiator matrix (or engine cooling fins) to a minimum. It took a while to really get it "right" and some designs did work better than others as some had several more years of laboratory work to go one or had more volume to put the ducts in.

Click to expand...

Hopefully the radiators would be of better efficiency as years go by, so the radiator of 1943 would make less drag than the one of 1941, per cooling capacity.

Jeffrey Quill, after his experiences in BoB made the list:

1. "Crash" programme for a huge improvement to the aileron control at high speed.
2. Major improvement to the optical qualities of the windscreen side panels.
3. Improvement in direct rearwards vision (bubble canopy).
4. Curing the problem of engine cutting under negative g.
5. Round counters.
6. Canopy de-icing, and fuel spray to wash oil deposits off the outside of the screen.
7. Cannon armament.
8. More performance and more fuel.

wuzak said:

The Mk IV (prototype Griffon engined Spitfire) first flew in 1941, IIRC. That lead to limited production of the Mk XII (basically the Mk V airframe with a Griffon engine) of 100 units.

The definitive version of the Griffon Spitfire was to be the Mk XX. A new, stronger wing design (not laminar flow) was to be used in the XX, but this didn't see production until late 1944/early 1945 in the Mk 21. Even then there were serious balance issues hat took time to sort out.

I can't see a laminar flow wing being around at a time which would make it useful to the war effort.

Click to expand...

US have had laminar flow wing in operative use in 1942, Japan in 1943, Germany was flying the prototype of Me-309 in mid 1942. So I see no problems for Brits to pull this one out for service use for 1943. Perhaps it just dawned too late to the designers, or people in charge?

wuzak said:

Just plonking the radiator in the fuselage doesn't guarantee that it will work. The Tornado prototype was originally fitted with a mid/rear fuselage mounted radiator (much like the Hurricane, in fact) but this didn't work very well, and the radiator was moved to the chin position, remaining there for the Typhoon and production Tempest Vs.

The Tempest I with leading edge radiators was some 20mph faster than the more powerful (by 100hp or so) Tempest II, and a little more than that against the Tempest V with the chin radiator.

I am glad that the Spitfire didn't get the belly scoop radiator - it would hav eruined the looks.

I do wonder what the effect of Bf109/Spiteful type radiators (lowline, trailing edge) would have been on a Mk VIII or XIV.

Click to expand...

The Italian 5 series had no problems with hull radiators, neither the Ki-61, but P-40 did. Wonder how good/bad the boundary layer was dealt with on all of those? So I won't push further with that; leading edge radiators are my favorites for quite a time now
Thanks for the speed difference figures.

1: Install a 'Germanic" style annular radiator (used on a tempest prototype) or the Lancaster/Beafighter style power egg installation.

This does three things
a/ it allows Rolls Royce to deliver complete engine/radiator units thus sinplifying installation.
b/ it removes the plumbing though the fueselage and wings and thus allows much more room for fuel in the wings as well as reducing weight.
c/ reduces the length of plumbing and hence battle vulnerabillity.


The Meredith effect on the Spitfire was not a particulary effective implementation.
The effect, which was widely known and understood well before
Meredith published a 'laymens paper'. Hugo Junkers, a Mechanical engineer and a thermodynaics
specialist had a patent on this dating from the 20's.
The Me 109F had a particularly elegant system complete with
boundary layer bypass ducts. The Tempest and Typhoon did not
havw wing radiators and did well without them. AFAIKT
the Ta 152 and FW 190D-9) recovered engine
cooling system waste heat via the radiator: note the cowling flaps
which would allow ejection of the heated air at optimal velocity.


2: Cleanup the underside smoothness of the wings. Its a bloody disgrace down there.

I've said 'wing leading radiators, like that Tempest prototype', ie. not serial produced Typhoon/Tempest. Picture:

File:Hawker Tempest I HM599.jpg - Wikipedia, the free encyclopedia

The Typhoon Tempest did well, but a 20+ mph increase in speed does seem like a god thing.

Siegfried said:

2: Cleanup the underside smoothness of the wings. Its a bloody disgrace down there.

Click to expand...

And so is your language.
There are a lot of misapprehensions being laboured under, here. The Spitfire tracking changed three times during its career. On the prototype, the legs were parallel, later they were splayed, slightly, and, from the Vc onwards, were moved forwards 2", and, hence, slightly wider. With the 21's new wing the tracking went from 5' 8.5" to 6' 4.25" an increase of 7.75".
Quill's report (I have a copy) did talk of ailerons, bullet-proof glass condensation, oil water cooling, armament armour ( he said that the pilot's head armour was too small,) round counters; he never mentioned a rear-view (bubble) canopy, canopy side windows, engine cutting, canopy de-icing, lack of fuel, or lack of performance, in fact he was adamant that it was superior to the 109. With regard to armament, he favoured retaing the 8 x .303", for straight fighter-to-fighter combat (this was September 1940 remember,) but was adamant that, for bomber work, the Spitfire needed 4 x 20mm cannon.
The Merlin XX was attractive, at first, because Hurricane production was due to end in April, 1941, but was revived so that the aircraft could be used for ground attack, for which their stability was ideal. At a stroke, this lost the XX, but this was not too serious, since, like the Hurricane, the III's fuselage was 4" longer, which made nosing-over a greater danger (hence the 2" greaker rake. By juggling with the carburettor controls, the Merlin 45, though longer, could still be fitted into the same cowling as the original I II.
So far, I've read through about 800 files, on the Spitfire, and nowhere is there any indication, from the RAF or Supermarine, of any dissatisfaction with it. The XIV wing was exactly the same as that of the VIII, so was not a special item, in any way.
The "serious balance issues," of the 21, were sorted in a month; Supermarine simply rounded-off the elevator horn, instead of keeping the more "squared-off" shape introduced on the V, VIII, IX, etc.
The Spiteful wing took advantage of the availability of the short-barreled Hispano Mk.V, which was not fitted into the Spitfire until the 24, since the Tempest got "first dibs."
Wherever you put the radiator, the pipework has to go somewhere, and a fuselage-mounted version would have deepened the fuselage quite considerably; sticking the pipes under the pilot doesn't make them any less vulnerable.