wuzak
Captain
So, a more expensive (I presume) Merlin 60 series engine to get the equivalent performance to a single stage Spitfire?
I think I'd rather use the 60 series in Lancasters....
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Mason notes that his figures are based on aircraft checked at the factory, rather than RAE figures:
giving 342 mph as a baseline, and pretending the performance gains would have similar to those of the Spitfire IXB over the Spitfire V (doubtful) the Hurricane Mk VII with Merlin 61 might have reached a maximum speed of c. 380 mph and maximum rate of climb of c. 3,300 ft/min, service ceiling @ 38-39,000 ft - roughly what a Spitfire Mk V was capable of.
Aozora, those numbers seem to confirm RCAFson's 342mph figure for the IIA. However, it also shows the IIB at 340mph, only 2mph slower.
Hurricane Mk II Performance shows a IIB with a top speed of 330mph @ 25,000ft.
Greyman and I have both stated that the Hurricane PEC was calculated incorrectly on the early tests (posted on WWII aircraft performance) hence the Mason figures matching the speeds with the correct PEC.
And you get that from where?
Not without strapping a rocket to it. Your source says 308mph (calculated) flight tests says 294mph. I averaged to 300mph (to make things simple, sue me for the 1mph) and used 1200hp. using the cube rule 1600hp gets you to 330mph. 570kph (353mph) requires about 1900hp. This is with NO CHANGE in drag. Is a retracting tail wheel and a trick mirror going to be worth bigger radiators? A heavier prop and more ballast in the tail (or does the retract system weigh enough ?) .
Maybe I screwed up the calculation?
The fact that the RAE recalcuted the correct speeds for the Hurricane I and II:
http://www.wwiiaircraftperformance.org/hurricane/hurricane-I-raechart.jpg
http://www.wwiiaircraftperformance.org/hurricane/hurricane-II-raechart-level.jpg
The first one identifies a revised PEC. The second one doesn't - it has no context.
I assume that the calculation system was incorrect, and that the Spitfire's speed was duly upgraded in a similar fashion?
Or are you gong to tell us they only got it wrong for the Hurricane?
In any case, Spitfire was faster in 1938 with Merlin II and 87 octane fuel than the Hurricane was in 1942 with the Merlin XX, 100 octane fuel and +12psi boost.
For N. Africa, one need to account for the performance losses, incured by installation of the tropical air filter. 11-13 km/h was lost (7-8 mph) for the Mk.2 (even more for Mk.1 - 48-68 km/h ???), according to the 'Monografie lotnize' book about Hurricane.
The V-1710s were able to do their job without the additional filter, maybe due to the more favorable intake position? We might also recollect that Merlin P-40s were without sand filters when introduced in N.A, sand playing havoc with engines, so the British helped the USAF with 600 engines worth of spares?
'WW2 with no Spitfire - Hurricane being primary interceptor'
Seems the plane of choice for the RAF early on in N.Africa was the Allison powered Tomahawks/Kittyhawks. Why not the Hurricane?
PEC is needed to overcome systemic instrumentation errors, usually caused by pressure variations around and inside the aircraft during flight. Since no revised figures have been published for the Spitfire, it may not have been a problem with it, and there's no guarantee that if there was an error that it would result in higher calculated speeds. Certainly this test seems to show somewhat lower speeds than earlier tests of the Spitfire:
Spitfire Mk V AA.878 Report (359 at 19900)
and it mentions a revised methodology as of 27 Aug 1942.
and an earlier test shows somewhat higher speeds at the same weight:
Spitfire Mk.Vc AA.873 Report (374 at 19000)
This aircraft is also somewhat heavier than earlier tests and it states that it is ballasted to full service weight.
No one is claiming that the Hurricane is faster than the Spitfire, just that the variation is not as great as early tests seem to show.
The differences in weight between those two tests was 48lb.
One had triple ejector exhausts with fishtails (AA.878 ), the other had them without (AA.873).
That said, the Spitfire Vc is still 30mph faster than a Hurricane IIc, going on the worst of those figures.
http://www.wwiiaircraftperformance.org/hurricane/hurricane-IIc-raechart-level.jpg
The IIa was good for for 551 km/h and i expect that it could make about 565 km/h with a cleaned up airframe and the MXX. A modded XX with SC gearing optimized for higher altitude would probably do a bit better at high altitude while one fitted with a Merlin 24 would probably make about 560-570 km/h at ~3km.
Here's what the Hurricane IIb can do with a Merlin XX at 3000rpm/9lb boost:
http://www.wwiiaircraftperformance.org/hurricane/hurricane-II-raechart-level.jpg
now lets imagine the same aircraft with a Merlin 24.
and then with a Merlin 60 series. The 60 series will give another 300-500 hp at altitude while the 24 will give 300-400 more at low altitude.
I'll crunch some numbers and reply later.
But what is in the timeline between 1940 till end of 1942 (arriving Merlin 60 for production/reality introduction of the Spit IX)?
You are building your whole what if on the reality and the help from the USA!
What will happened if things change?
I have given you some examples in my post 357:
1. What will happen if Goering didn't give the stupid close cover order for the LW fighters during BoB
2. What will happen if the RLM would choose the FW 187 instead of the Bf 110?
3. What will happen if the Bf 109 E7 (could carry 300 Liter drop tank) will introduce earlier in time of the BoB?
4. What will happenn if Germany didn't attack UDSSR, but concentrate only at GB?
Example 1,2 and 3 are all technical possible from the timeline. I don't claim that only the Hurricane in use at the RAF and the FW 187 and the Bf 109 E7 will change in summary the outcome of BoB, but I claim that the losses to the RaF without the Spit and only with Hurricane in use and with the 3 possible changes would be back-breaking from pilot losses and a/c losses, with much less losses for the LW then in reality.
There would be not much at 1941 that could defend against a introduced Bf 109F-4 with the Fw 187 and the Fw 190 is showing at the horizon at summer 1941. Your losses would be at least 100% higher then in reality (to my opinion I tend to 150%-200%) and where will you get trained pilots to fill the losses?
Realy I can't see any real advantage of your what if, except perhaps to get some more a/c's for a shorterm timeline but with the costs of realy big disadvantages for near 2 years at all frontlines (defending GB, Mediterranean area and NA).
Also I can't see that a Hurricane with the Merlin 60 will be realy at the same level as the FW 190A3, Bf 109F-4 or Bf 109G2.
The Hurricane I could do ~325mph TAS or 271 IAS at 10000 ft with ~1300hp (MerlinIII 12lb boost at FTH):
http://www.wwiiaircraftperformance.org/hurricane/hurricane-l1717-cal.jpg
so if we give the same aircraft 1400hp (merlin 60 series 15lb) at 25000ft we should still get 255- 260 TAS or about 383 - 390 mph TAS.
It's just about impossible to consider an ATL if things change too much, but your points 1-3 would make things equally tough for the RAF in the OTL. Remember that in the ATL I postulate, that Hurricane production is increased with 3 additional Hurricanes for every 2 Spitfires produced in the OTL. I fully acknowledge that the Hurricane design would run out of growth potential in 1942 without a new wing and/or volume production of Griffon.