Low level interceptors - Spitfire XII vs Typhoon

[wuzak]

A former member of this site PM'd me with some comments about the La-7 thread.

He was of the opinion that some of the Hawker products were better low down performers than the La-7, though I pointed out that they had 500hp+ more power.

Anyway, We got around to comparing the low down attribues of the Typhoon and the Spitfire XII.

The following reports were compiled aound the same time - in late 1942.
Spitfire Mk XII DP.845 Report
Typhoon IB Performance Data

When we put the speed, time to climb and rate of climb data into graphs we get:

DP845 was a prototype XII - at the time of the trial it was fitted with a fixed tail wheel, though it had the retractable type earlier.

Production XIIs were fitted with the clipped wing tips which allowed for very good roll rates, but reduced the service ceiling to 28,500ft, compared to 32,200ft for the Typhoon.

The Typhoon had substantially more firepower (4 x 20mm vs 2 x 20mm + 4 x 0.303"), though the Spitfire could have matched it if so desired (the XII had the universal wing).

The Typhoon was improved quite susbtantially over the following year or so, with more power and some tidying up of the airframe.

Only 100 Spitfire XIIs were made, with a few of them using the Griffon VI in place of the Griffon II. This reduced the top speed in FS gear by a 8 mph, and improved top speed in MS gear by a few mph, but greatly improved rate of climb.

Which is your choice for low level interceptor work?

 

[Shortround6]

This chart from Mr. Williams site is rather interesting.

http://www.spitfireperformance.com/spit14at21.jpg

the last box on the right with the distances and times needed to overtake an "bumble bomber" (V-1?) that was doing 350mph from 1 mile behind.

Granted the Spitfire is a MK 14.

 

[drgondog]

To get that TAS on the deck for the P-51B w/1650-7, even with 25# boost implies taking off the wing racks and carrying half fuel tanks..

 

[timmy]

Are there any other challengers to the Griffon Spitfires and Sabre Typhoon from a Western perspective ???

As far as a Low level interceptor I cannot think of any other plane in this Period
Maybe the A-36 was fast but didn't have much of a climb rate. P-51B didn't see service until later in the war correct?

 

[wuzak]

Are there any other challengers to the Griffon Spitfires and Sabre Typhoon from a Western perspective ???

As far as a Low level interceptor I cannot think of any other plane in this Period
Maybe the A-36 was fast but didn't have much of a climb rate. P-51B didn't see service until later in the war correct?

P-51/P-51A/Mustang I/Mustang II would be better than the A-36. It is about as fast as the two listed here.

The P-51B became operational in late 1943. Spitfire XII entered combat in April 1943, the XIV in early 1944 and the Typhoon in 1942. The Tempest V started in April 1944.

 

[wuzak]

There were lots of tests to improve the performance of Typhoon. Perhaps teh best performance cme in August 1943.

August 1943.

Cleaning up.

The remaining cleaning up modifications are now on the production machine.

These are (a) Exhaust shrouds.
(b) Whip aerial
(c) Sliding hood.

Tests at Gloster on a repaired aircraft with a whip aerial and sliding hood fitted have given the following level speeds corrected on the basis of A. A.E.E. Res.170.
M.S. M.P.A 398 m.p.h. at 8,800ft
F.S. M.P.A 417 m.p.h. at 20,500ft.

• This represents an increase of some 7 m.p.h. in F.S. and some 4 m.p.h. in M.S. due to the sliding hood and aerial.
• They are the fastest speeds yet obtained on any Typhoon aircraft. The maximum speed is some 12 m.p.h. better than the prototype Typhoon 1B and represents a total increase of some 35 m.p.h. compared with the worst Typhoons tested at Langley.

Typhoon IB Performance Data

 

[wuzak]

Of course straight line speed is one thing, and the aircraft mentioned all had enough at low level to catch the Fw 190A at low level, which was a problem around the end of 1942, early 1943.

There are also climb, roll, turn and firepower considerations.

 

[Koopernic]

On the surface of it the RAF could have lived without the Typhoon apart from the advantage of occupying Hawker's and Napier's production facilities, given its teething problems and given that when it was debugged the Spitfire XII was available and trouble free.

When did the cropped wing spitfires with high RPM reduced diameter superchargers enter service?

Typhoon and Fw 190A speed seems to have tracked itself closely with neither one much different from the other in speed.

Fw 190D9 with a modified 1 speed gear ratio that optimised them for sea level speed were able to reach 640kmh/400mph at sea level. Remarkable for being with a bomb rack fitted and using ordinary fuel. They never entered service.

See curve 3 headed "A ladder als Boddenmotor". The term "boddenmotor" means a motor is optimised for the ground or 'bottom'. ie is optimised for sea level work.
http://www.wwiiaircraftperformance.org/fw190/fw190d9speed2chart.jpg

 

[Shortround6]

When did the cropped wing spitfires with high RPM reduced diameter superchargers enter service?

Clipped wings started showing up in the Fall/Winter of 1942.

The cropped impeller Spitfire V Merlins used the same 9.089 gears as the uncropped Melrin 45 series (some marks differed in two piece cylinder blocks or type of carb but performance stayed the same).
The cropped impeller engines show up about the same time or a just a bit later. Please note that designation 'LF' refers to the engine fitted and not to the wing type. Some clipped wing planes had normal superchargers and some cropped impeller planes had normal wing tips.
LF two stage engines (Merlin 65) used the same impellers as the 'normal' two stage (or HF Merlin 70) engines but used different gear ratios to supercharger. Both of these engines (and their close siblings) used a larger diameter 1st stage than the Merlin 61.

Of interest is that a Merlin 65/66 at 18lbs boost offers almost the same power as a Griffon II at very close to the same altitudes which may help explain the low production of Spitfire XII aircraft. Once they beefed up the Merlin 60 series to operate at 18lbs boost the power difference with a Griffon II?III/IV operating at 12lbs was very small. The Later Griffon VI was cleared for 15lbs boost but doesn't show up until 1944?
Spitfire XIVs with Griffon 65s used 18lb or 21lb or more boost.

 

[davparlr]

To get that TAS on the deck for the P-51B w/1650-7, even with 25# boost implies taking off the wing racks and carrying half fuel tanks..

Maybe that was the criteria. They do show a test of a P-51 III achieving a top speed of 404 mph at 2k altitude at a gross weight of 8800 lbs (120 gallons of fuel?) and pulling 25 lb/sq.in. Of course this was mid-1944.

Mustang III Flight Trials