Letīs talk about the tempest

[Naudet]

 

Out of curiosity I plugged the Tempest and the 190A5 into Zigrat's nifty spreadsheet, and amazingly they could produce a nearly identical sustained turn.

were can i find this sheet and how to get turn speed (degree/sec) and radius (ft.) outta it??

[niklas]

S!

Buzzbait, weight plays only a minor role when you look at the topspeed. But the theoretical CD0 of the tempest is very low (~0,014). Of course all aircrafts with large wingareas have naturally a lower CD0 compared to fighter with higher wingloading.

Sable is it possible to have a turnrate in Zigrats sheet when you enter "1G" ?? If so than thereīs a little bug in it.
What does the climbrate of Zigrats sheet say about the tempest? I got for my sheet 4050ft/min for the dora (very close to the FW-data), but only 3700ft/min for the tempest...(2430hp)

@funked
i didnīt make some real calculations so far, i basically compared the performance claims to the performances of other fighters. And when several different sources / stories / tests show that the tempest wasnīs a really good turnfighter, and it performs here completly different, then something has to be fixed, right?

niklas

[funked]

Well the AFDU turn comparisons are for a plane with Sabre II and only 2090 hp.  Wouldn't the extra 300 hp help a bit? And how do we know that the AH Tempest does not have a Sabre V?  Then you are looking at 500 hp more than the AFDU test and 200 hp more than the A&AEE figures.  Which actually makes sense, because low level speed and climb in AH are in excess of the A&AEE figures.  500 hp would probably help the turn rate a whole bunch.    

Also AFDU appears to consider only turn radius, not turn rate.

Another factor - early Tempest V had the same long Mk. II cannon with barrel fairings as the Typhoon.  AH has the Mk. V cannon completely inside the wing.  Maybe AFDU tested one with the Mk. II cannon, which would have affected CL and CD of the wing? http://user.tninet.se/~ytm843e/cannons.htm

Yet another factor - in any comparisons with the Typhoon, remember that the Tempest has a 4-bladed prop vs. 3-blades on the Typhoon.  So it seems maybe the Tempest would able to get more thrust at low speeds than the Typhoon, even with the same engine.

I don't know the answers, but these are all real factors that have to be considered.

[This message has been edited by funked (edited 03-21-2001).]

[Glunz]

Dora vs Tempest is very fun fight. Pilot quality is the main factor here.

Even Pierre Closterman (sp) can say something about that, right ?  

Fighting a Tempest really adds a challenge to the Dora. Other planes don't come close.

[mw]

Air intake efficiency was measured on JN.731 by the A.& A.E.E. Here's a brief summary of the results:

Measurments of air intake efficiency under various conditions of climbing and level flight have been made on Tempest JN.731.

Intake efficiency %

Climb at combat power Radiator flap open
Vi mph....8000 ft. ....19000 ft. .... 28500 ft.
140 ....... - .......... 162 .......... 135
160 ...... 178 ......... 151 .......... 129
180 ...... 159 ......... 142 .......... 124
200 ...... 148 ......... 134 ........... -
220 ...... 139 ......... 131 ........... -
240 ...... 133 .......... - ............ -

Level flight Radiator flap closed
Vi mph .... 8000 ft
180 ....... 123
220 ....... 118
260 ....... 116
300 ....... 116
340 ....... 116
380 ....... 116

Examination of the results obtained will disclose some rather unusual features, the most striking of which are :-

i. The efficiencies obtained are surprisingly high.
ii. The efficiencies when plotted against Vi do not lie on the same curve at all heights but vary with height.
iii. Despite ii. the rams plotted against true airspeed appear to lie on one curve at all heights (for a given flight condition, such as climb).

Conclusions:
The air intake system of the Tempest V is very good, and the efficiencies, expressed relative to the forward speed of the aircraft, exceeded 100% by varying but appreciable amounts.
This fact is due not only to good design of the intake itself but also to the positioning of the entry to the intake which is such that full advantage is taken of the slipstream from the propeller.

Both Tempests used in the AFDU and AAEE were production aircraft of the JN series from the first batch of 100 built.  


------------------
Tempest Performance Testing
Spitfire Performance Testing

[Zigrat]

my spreadsheet is only about 90% accurate

i recently got a new book and it has some prop efficiency curves  


so i should be able to make it more accurate, but it will still be difficult to include factors in the spreadsheet such as different wing efficiencies since all planes are different.

but i can probably get the accurac up to 95%

[Sable]

Well, I realise it isn't perfect, but it definitly makes a nifty tool for "napkin" type calculations.  Honestly, I don't think it's too far off from what the flight models in WB or AH are doing.

As for measuring a turn rate with it, the trick is to increase the G until you can find the lowest speed where T-D =~ 0.  This will give you the best theoretical sustained turn speed.

Ignoring that stuff though, I would still be worried if a fully loaded Tempest were stalling at about 10 mph below the "book" number for it.

Sable
352nd FG

[niklas]

 

Well the AFDU turn comparisons are for a plane with Sabre II and only 2090 hp. Wouldn't the extra 300 hp help a bit? And how do we know that the AH Tempest does not have a Sabre V?

Unfortunatley they didnīt mention whether they used always normal power setting ( 2090hp)or whether they switched for several tests to combat power.

I think youīre right with the Sabre V engine. It really looks like that our AH Tempest has the 2600hp Sabre V engine. This would explain the huge difference in climbrate between the Tempest and Typhoon , 1k/min, (though the climbrate is imo still too good), and the rated altitudes are very smiliar to the Sabre V of your engine chart.

btw our typhoon has also a 4-bladed propeller

niklas

[This message has been edited by niklas (edited 03-21-2001).]

[F4UDOA]

Juzz,

Where have you seen a FW190G-3 tested by the USN? I have test data of the FW190A-5.

Funked, maybe I'm missing engine specs. But the sustained climb rates vrs sustained climb time IMHO do not seem to correspond.
For instance the sustained climb of the NIK2 appears to be similar if not a little worse that the Tempest. However the climb time to 20K I believe is a little better. But when compared in average rate of climb the Tempest should be superior.

[F4UDOA]

BTW Gents,

The low drag of the Tempest is measured at level flight. With a laminer wing that drag increases at a higher rate at high AOA than a conventional higher lift wing. This is the draw back of a laminer flow wing.

So when your pulling through your turns in a P-51 or Tempest at high AOA your wing design may not be at it's most efficient state.