Hurrican evolution - you are the boss ;)

[tomo pauk]

Hi, Edgar,

The only other problem was that the Americans wouldn't sell us their superchargers; it's why the P-38 turned out to be useless.

Would you be so kind to elaborate a bit about that?

As for Hurricane with V-1710 - why bother?

 

[Shortround6]

The rear hull tank(s) for Spitfires were much far aft than it was the case for P-40 (though they were shoving there some ~70 gals in the Spits). Or, as can be seen down, for the proposed Hurricane's installation:

The difference is that the P-36 was designed from the start to have that fuel tank where it was, it was not added several years later. The P-40 inherited the tank set-up and the rear tank was part of the P-40 design process from the first day pencil was put to paper. In fact it was such an integrated part of the design that when the "L" and "N" stripper models were built and a tank left out to lighten the plane, of the 3 tanks available the rear tank was left in and one of the tanks in the wing center section was the one that came out. Without knowing all the the different weights and balance arms involved it would be very difficult for an engineer to figure it out let alone most us on this forum.
Some wings (airfoils) were more tolerant of CG shifts than others. Some governments were a little more tolerant of certain flight characteristics at aft CG limits than others ( I have heard it said that the DC-3 Could not be certified under today's rules at it's aft CG limit).
Just because one or two airplanes could be flown with aft tanks doesn't mean all fighters could be.

 

[wuzak]

Hi, Edgar,



Would you be so kind to elaborate a bit about that?

Actually I believe the RAF requested the P-38 without turbos, so that they had common engines with the P-40s they were getting. RAF Lightnings also had the engine both turning on the same direction, as opposed to the P-38 which had counter rotating engines/props.

 

[tomo pauk]

The difference is that the P-36 was designed from the start to have that fuel tank where it was, it was not added several years later. The P-40 inherited the tank set-up and the rear tank was part of the P-40 design process from the first day pencil was put to paper. In fact it was such an integrated part of the design that when the "L" and "N" stripper models were built and a tank left out to lighten the plane, of the 3 tanks available the rear tank was left in and one of the tanks in the wing center section was the one that came out. Without knowing all the the different weights and balance arms involved it would be very difficult for an engineer to figure it out let alone most us on this forum.
Some wings (airfoils) were more tolerant of CG shifts than others. Some governments were a little more tolerant of certain flight characteristics at aft CG limits than others ( I have heard it said that the DC-3 Could not be certified under today's rules at it's aft CG limit).
Just because one or two airplanes could be flown with aft tanks doesn't mean all fighters could be.

I will not bet my house on anything that is not flown with such-and-such modification. OTOH, I believe I've made a good case for the additional fuel tank for Hurricane.

 

[Edgar Brooks]

There is plenty of room in Hurri; battery can go above the fuel tank that is, in preliminary 30 gal version, less than 2/3rds of P-40 rear tank's volume. The 12V is 12V, no matter what type of battery it is, anyway..

Batteries can spark; spark + fuel = explosion

Granted, you are very knowledgeable person when it comes down about British planes, yet, in the Spit V pilot's notes such a procedure is nowhere to be found.

Purchase A.P.1565E (the manual for the Spitfire V); you'll find the instruction in there.

As for the kind of runaways the Hurri would be taking off, it was lighter than P-40F by some 1000 lbs as-is, with 10% more wing area. Nothing to worry there; P-40 was renown for it's ability to use dirt strips

You're forgetting (again) that the Hurricane was no longer a fighter, and that side of its use was over; where it was forced to continue (e.g. Malta) it was decimated. Add bombs, rockets, 40mm cannon, etc., and the Hurricane is no longer 1000lbs lighter than the P-40. You wouldn't have found many dirt strips, here, either; grass fields tend to be quite soft during three of the four seasons in the U.K.

 

[Edgar Brooks]

Would you be so kind to elaborate a bit about that?

No; that's how it's been reported, here, for years. If anyone has evidence that refutes it, I'll withdraw it.

As for Hurricane with V-1710 - why bother?

If you check back, you'll see that I was responding to another contributor's suggestion; that is permitted, I presume?

 

[tomo pauk]

Okay, then the battery is going above the fuel tank, just to be on the safe side
The excerpt I've posted is taken from the document you're talking about (Air publication 1565E).
The P-40 would repeatedly take off with bombs, drop tanks, full ammo internal fuel in Asia/Pacific and N. Afica, so Hurricane is not in disadvantage there, at main theaters it should appear in 1941 and later. And there it was very much a fighter.

If you check back, you'll see that I was responding to another contributor's suggestion; that is permitted, I presume?

Sorry for the confusion, I was not answering to you but the person suggesting the V-1710s in Hurricanes (Sigfried?).

As for the turbos for British P-38s, the Brits wanted standardization with the P-40s being bought, so they started to receive planes with 'C' series V-1710s, without turbo installation and all engines turning in same direction. Made a mess with P-38's performance handling.

 

[Edgar Brooks]

The rear hull tank(s) for Spitfires were much far aft than it was the case for P-40 (though they were shoving there some ~70 gals in the Spits). Or, as can be seen down, for the proposed Hurricane's installation:

The 29gal tank was not to be used for combat, just for ferrying; it could only be used in combination with the 170gal ferry tank. You might not like the rule, but that's how it was.
The only wartime Mark(s) with permanent tanks behind the pilot, were the low-level XVI F.R.XIVe, which had the heavier 60-series Merlins Griffons to counterbalance the weight, and, even then were instructed to use it first; the tanks carried 66gal, not 70, in the "bubble canopy" XVI, while Group commanders refused to countenance rear tanks in the high-back IX, since, as they were being used for escort work, they adversely affected height, rate of climb, and manouevreability. Post-war, use of the tanks was banned, as a safety measure.

 

[Siegfried]

As I've already pointed out, the Hurricane had been written off, as a fighter, and was not projected beyond early 1941; it was only continued because of its ground-attack capablities. Stop considering it as a fighter, since the Air Ministry certainly had.

Merlin XX, not XXIV, which was a boosted engine intended for the Lancastrian; the Spitfire V did not "miss out," since it was never planned to take the XX. It was possible to get the Merlin 45 into the same space as the Merlin II/III, so, apart from eventually strengthened engine bearers, the V was an easy conversion. The XX-powered Spitfire III needed a redesigned engine compartment, strengthened fuselage, extended engine bearers, strengthened and extended (forwards) u/c, and, after all that, its top speed still didn't reach 400 mph.


That's what happened, anyway.

The only other problem was that the Americans wouldn't sell us their superchargers; it's why the P-38 turned out to be useless.

As I've already shown, it could not, since the Spitfire III's top speed was only 395; the two-stage Merlin was absolutely essential, to give the VIII/IX an even chance against the 190

I don't accept that the Spitfire V with a two speed Merlin needed the extensive modifications you state. The two speed Merlin XX barely had more power than the single stage (maybe 1480 instead of 1280 hp) but the key to performance was that it could maintain this level of power over a broader range of altitudes. Only 200 extra hp (15%) isn't going to rip appart the airframe. When the FW 190 started decimationg Spitfire V's and the Two stage Merlin was rushed into the Spitifre V to create the Spitifre IX non of these extensive modifications were introduced. Placing a Merlin 20 series (with a two speed supercharger) is going to be much easier than a two stage intercooled Merlin 60 series with its greater length and much greater cooling requirements (due to the intercooler).

If the Spitifre V with Merlin XX could manage 395 it is still 25mph faster than the Spitifre V with a Merlin 45 (single speed). This is enough to cope with the FW 190A2 and early A3 since these aircraft indidn't have the full 1700hp 1.42 ata rating but were restricted to 1.3 and 1.37 ata initially and were sub 400mph aircraft as well.

Of course the reason the Spitifre was never scheduled into production with the Merlin 20 series is because these precious engines were being absorbed by Hurricane prioduction. Putting a cropped supercharger (Merlin 45M) into the Hurricane II makes more sense as the Hurricanes only use is ground attack it should be engaging in combat above 10000ft or even be in the danger zone that long. The Spitifre V/Merlin 20 however would seem to gain a potent 20-25mph.

 

[tomo pauk]

@ Edgar:
No doubt that anything added to a fighter makes it less of a performer, the additional ~600 lbs of fuel+tank plumbing being point in case.
That addition, in effect in late 1944, was too late to effect the war in Europe, even more so since RAF was able to position it's fighters on the Continent. The rear hull tank(s) in, say, 1943 make more sense, even if that's only half of that quantity.
BTW, when I write "~", that means "circa"

I've covered the V-1710 issues in previous post (edited).

 

[Edgar Brooks]

Okay, then the battery is going above the fuel tank, just to be on the safe side .

Safe? You're putting the fuel tank and the battery right beside the upward-firing pyrotechnic recognition device. Rather you than me; there was also a chute, back there, which contained a downward-firing parachute flare, and the I.F.F. radio had an explosive device fitted to it. And don't say that they could be moved back, since theCofG considerations wouldn't have allowed it.

 

[Edgar Brooks]

I don't accept that the Spitfire V with a two speed Merlin needed the extensive modifications you state.

I'm not really interested in whether you accept it (though I would prefer you not to call me a liar); it happens to be the truth. The XX was 4" longer than the III and II, so the fuselage also had grow by 4". This entailed longer, and stronger, engine bearers, a stronger (and raked-forward) undercarriage, and a stiffened fuselage. The XX also needed extra cooling, which means a larger radiator, which means more drag.

The two speed Merlin XX barely had more power than the single stage (maybe 1480 instead of 1280 hp) but the key to performance was that it could maintain this level of power over a broader range of altitudes. Only 200 extra hp (15%) isn't going to rip appart the airframe.

So you're saying that Supermarine didn't know what they were doing (with their own aircraft,) when they felt the need to strengthen the fuselage and engine bearers, even to cope with the extra torque from the Merlin 45-series? According to Rolls-Royce, the XX developed 1280hp @ 3000rpm, not 1480, and was also far more complicated than the II, III, 45, etc. The carburettor was separate from the blower, for a start.

When the FW 190 started decimationg Spitfire V's and the Two stage Merlin was rushed into the Spitifre V to create the Spitifre IX non of these extensive modifications were introduced.

The Fw190 is something of a red herring, since the Spitfire V was introduced as a counter to the 109F; at the time construction was started the 190 was unknown.

Placing a Merlin 20 series (with a two speed supercharger) is going to be much easier than a two stage intercooled Merlin 60 series with its greater length and much greater cooling requirements (due to the intercooler).

Not according to Rolls-Royce, who carried out the first 285 IX conversions, and the XX also needed extra cooling.

If the Spitifre V with Merlin XX could manage 395 it is still 25mph faster than the Spitifre V with a Merlin 45 (single speed). This is enough to cope with the FW 190A2 and early A3 since these aircraft indidn't have the full 1700hp 1.42 ata rating but were restricted to 1.3 and 1.37 ata initially and were sub 400mph aircraft as well.

Only if you know of the existence of the 190, remember? The Air Ministry was hardly likely to know about the early 190's limitations, until they captured one, and test flew it; it's very easy to apply hindsight to a discussion like this, try going back 70+ years, with the knowledge tat the time.

Of course the reason the Spitifre was never scheduled into production with the Merlin 20 series is because these precious engines were being absorbed by Hurricane prioduction.

They were not seen as "precious" by R-R, they were a confounded nuisance. They were also used in the Halifax II, Defiant II, Beaufighter II, and Lancaster I, so putting them into another airframe was not a good idea.

Putting a cropped supercharger (Merlin 45M) into the Hurricane II makes more sense as the Hurricanes only use is ground attack it should be engaging in combat above 10000ft or even be in the danger zone that long. The Spitifre V/Merlin 20 however would seem to gain a potent 20-25mph

Cropping superchargers did not start until mid-war, and work started on the Merlin 60-series in March 1940; originally planned for high-level bombers, it was moved sideways into fighters.

 

[tomo pauk]

Since we're done the P-39 and Spitfire to death, any new ideas for the Hurricane?

 

[Just Schmidt]

Well, I'm game.

Hereby I proudly presents (the concept of) the Hurrytwin...

More serious (though I won't pretend to know for a fact they didn't try or contemplate), but still with perfect hindsight: Hurricanes for Burma with 4 12.7's instead of 12 (or 'just' 8 )of small caliber. Heck, why not 2X20 and 2x12.7?

And while I'm at it, make the rear of that bubble hood transparent.

That's admittedly quick and dirty from the top of the deck. More serious fiddling I'll leave to the engineers.