Author Topic: Typhoon speed performance (Read 2238 times)

Flyboy · « **on:** May 29, 2005, 10:58:51 AM »

I started THIS THREAD in the general forum. i think it should be here tho.

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here are some figures to play around with.

in AH on the deck, fuel burn set to 0.0000000 (no burn at all)
the bolded number indicates WEP

typhoon at 25% fuel: 372 / 357
P51d at 25% fuel: 368 / 355

typhoon at 100% fuel: 371 / 356
P51d at 100% fuel: 366 / 354

the thing that stand out the most is the fuel load barely make any difference in speed.

anyone care to explain why? or is it a bug?

then i found the following Flight test

now im No expert, but clearly there is something very wrong in either AH or the test they performed.

Here are the contradictions i found between the report and AH tiffi.

- deck speed is wrong, AH tiffi is faster at 357 compared to 345.5.

- according to the source the overall top speed of the tiffi (whats the correct technical name?) is at 20,200feet and is 394.5Mph. AH tiffi does 400MPH.

- AH tiffi fail to hold a boost of +7 at 20,200.

- the source states

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-------------------------- R.P.M.    Boost lb/sq.in.
Maximum permissible for climb   3500   +6
Maximum permissible for level flight (5 min. limit)   3700   +7

AH tiffi can hold +7 boost for unlimited amount of time.

Another thing i dont understand about the reort is when did they engage the 2nd phase of the SC.
in the climb chart it shows 12,600feet but on the speed chart it shows 15,000feet.

lastly, the report figures are quite low, anyone have a different performance figures?

Nashwan · « **Reply #1 on:** May 29, 2005, 01:38:44 PM »

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ow im No expert, but clearly there is something very wrong in either AH or the test they performed.

Here are the contradictions i found between the report and AH tiffi.

- deck speed is wrong, AH tiffi is faster at 357 compared to 345.5.

That test is for a very early Typhoon.

It ran at 7 lbs boost with a 3 bladed prop. The AH Typhoon is a later version with a 4 bladed prop (iirc) and running at 9 lbs boost, which provides a lot more horsepower.

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- AH tiffi fail to hold a boost of +7 at 20,200.

What boost does it hold?

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AH tiffi can hold +7 boost for unlimited amount of time.

The Typhoon with the Sabre IIa engine had a 1 hour limitation of 7 lbs, which is, to all intents and purposes, unlimited.

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Another thing i dont understand about the reort is when did they engage the 2nd phase of the SC.
in the climb chart it shows 12,600feet but on the speed chart it shows 15,000feet.

Ram air effect. The faster you go, the more air builds up in the intake, increasing effective air pressure. So at high speed you can maintain a higher boost level at a particular altitude than at low speed.

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lastly, the report figures are quite low, anyone have a different performance figures?

Well, that's an early Typhoon, 3700 rpm 7 lbs boost. The Sabre IIa allowed 3700 rpm, 9 lbs boost, the Sabre IIb 3850 rpm, 11 lbs boost (and possibly as much as 13 lbs). Don't know how many Typhoons recevied the Sabre IIb though.

Kev367th · « **Reply #2 on:** June 05, 2005, 10:35:13 AM »

Did a little more research -

The Sabre IIA was fitted to the first 105 Tiffys only, after that the Sabre IIB then the IIC became standard. Guessing ours is the IIB or IIC. More likely IIB as over 3000 Tiffys were made.

Tail probs - Initial 'fix' was started in 1942 by adding a row of strengthening fishplates round the rear fuselage.
Later on a Tempest tail was fitted (we dont have that)

Prop - According to the Air Ministries own documents this did little more than reduce the take-off run by 150 to 200ft. Fitted in 1944.

So it begs the question - How many 4 bladed, Napier IIB Tiffies were around in 1944, or had most been upgraded to the Sabre IIC?
Could it be we not only have a dog Spit 9, but a dog Tiffy also? If so we have a 1942 Tiff with a 4 bladed prop.

Still hard to find 'official' performance graphs.

straffo · « **Reply #3 on:** June 05, 2005, 11:20:00 AM »

I've no idea of the number of typhoon with 4 blades propeller.

Krusty · « **Reply #4 on:** June 05, 2005, 11:34:06 AM »

internal weight (gas load) will not affect the top speed of a plane.

It will affect the acceleration, the time it takes to GET to that top speed, but you will arrive at the same top speed.

Kev367th · « **Reply #5 on:** June 05, 2005, 12:20:28 PM »

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Originally posted by straffo
I've no idea of the number of typhoon with 4 blades propeller.

Wierd that goes against what I read saying only the 1st 150 Tiffs off the produciton line had Sabre IIA's.
In fact it looks very suspicious, theres no mention at all of the Sabre IIC fitted to later aircraft.

straffo · « **Reply #6 on:** June 05, 2005, 03:44:53 PM »

Source is : Hawker Typhoon Tempest and Sea Fury by Kev Darling.

I'm still tring to find a book by Christopher Shores suposed to be more accurate.

Kev367th · « **Reply #7 on:** June 05, 2005, 03:46:46 PM »

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Originally posted by straffo
Source is : Hawker Typhoon Tempest and Sea Fury by Kev Darling.

I'm still tring to find a book by Christopher Shores suposed to be more accurate.

Kev Darling, Lol thats OK Straffo Sweetie.

straffo · « **Reply #8 on:** June 05, 2005, 04:02:51 PM »

didn't noticed the author name

As I've it in front of me ISBN : 1 86126 620-0

If you are a 2TAF fan I urge you to get :
2nd Tactical Air Force Volume One "Spartan to Normandie" by Christopher Shore and Chris Thomas
ISBN :1 903223 40-7

MiloMorai · « **Reply #9 on:** June 05, 2005, 04:37:28 PM »

If you want Typhoon (and Tempest) production numbers read:

The Typhoon and Tempest Story
Thomas & Shores
ISBN 0-85368-878-8

The Hawker Typhoon & Tempest
Mason
ISBN 0-946627-19-3

.............

Kev, where did you find that the Tempest tail was fitted?

The majority of the 4th production run (5-4-43 > 7-12-43) of 600 serialed JP and JR had there IIAs replaced by IIBs.

Kev367th · « **Reply #10 on:** June 06, 2005, 12:17:36 AM »

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Originally posted by MiloMorai
If you want Typhoon (and Tempest) production numbers read:

The Typhoon and Tempest Story
Thomas & Shores
ISBN 0-85368-878-8

The Hawker Typhoon & Tempest
Mason
ISBN 0-946627-19-3

.............

Kev, where did you find that the Tempest tail was fitted?

The majority of the 4th production run (5-4-43 > 7-12-43) of 600 serialed JP and JR had there IIAs replaced by IIBs.

Sorry, I should have been more specific, my bad -
They found the problem with shedding tails was caused by vibration.
Qucik 'fix' was to strengthen the area with fishplates, later on they fitted a Tempest type tailplane that cured the problem.

When was the Sabre IIC used?

MiloMorai · « **Reply #11 on:** June 06, 2005, 04:24:44 AM »

Kev, you do know that the fin of the Tempest was just a filleted Typhoon fin. AFAIK the slightly increased sized stab and elevator was not fitted to the Typhoon.

The fishplates added hardly any strength and was more for reassurance of the pilots. The tail failures were due to fatigue failure of the elevator mass balance mounting bracket. (see pg 40-42 of the Mason book for more detail)

Angus · « **Reply #12 on:** June 06, 2005, 04:34:19 AM »

Emm:
"internal weight (gas load) will not affect the top speed of a plane.

It will affect the acceleration, the time it takes to GET to that top speed, but you will arrive at the same top speed."

Not exactly. Adding weight adds induced drag. But on that kind of a plane it does not make very much of a difference.

Kev367th · « **Reply #13 on:** June 06, 2005, 08:47:22 AM »

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Originally posted by MiloMorai
Kev, you do know that the fin of the Tempest was just a filleted Typhoon fin. AFAIK the slightly increased sized stab and elevator was not fitted to the Typhoon.

The fishplates added hardly any strength and was more for reassurance of the pilots. The tail failures were due to fatigue failure of the elevator mass balance mounting bracket. (see pg 40-42 of the Mason book for more detail)

According to the Air Ministries own records the increased sized stab and elevator were fitted.

mw · « **Reply #14 on:** June 06, 2005, 10:49:05 AM »

Neil Stirling & I have been working on Typhoon Performance. We’ve not sorted it all out yet, but here’s a start:

Typhoon Performance

The tests are not perfect – they hardly ever are. R.7700 had extended exhaust stubs (for CO contamination tests) With respect to R.8762 it was noted that: “This aircraft has been on test work for a considerable time, and the external finish of the aircraft has deteriorated during this period. The results should not therefore be regarded as typical for new production aircraft. This deterioration will not, however, invalidate the comparison between the results at combat and old all-out level rating.”

That said, the Typhoon IB Aircraft Data Sheet gives performance with 9 lbs/3700 RPM as 374 mph at 5,500 ft and 405 mph at 18,000 ft. These figures correspond reasonably well with R.8762 at +9 lbs when the condition of R.8762 and its lower FS gear height are taken into account.

Comparing to AH:

The FTHs seem to suggest +9 lb boost, the speeds suggest +11 lbs boost. Bit of a puzzle really... Could be +11 lbs (Sabre IIB), but I don’t think the FTH’s match that.

Edit: To hopefully clarify; the only logical conclusion I can make with respect to AH is that the black line in the AH chart is +9 lbs, and the red line (emergency) is +11 lbs.