Author Topic: why spit14 is perked and not 16  (Read 3602 times)

Offline SgtPappy

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why spit14 is perked and not 16
« Reply #105 on: December 28, 2006, 07:40:36 PM »
Ok back to the XIV's turning.

According to WW's great info, the XIV has a turning circle some 20% worse than the IX - over 55 feet of extra turning circle.

According to RAF tests, the XIV's turning for the 2 planes were 'identical'. Now of course this sentence is far from good, but doesn't it show that the XIV turned so similarly to the IX that a 55' difference would seem quite overdone?

Yes, the XIV MUST turn worse than the IX, but if the test is correct, the XIV must have some quality that allows it to turn so well. My theory is power loading. WW's tests show turning conclusions from turn index. Though those tests are great, the power of an a/c must give better flat, straight forward turning.

'No. By that argument, the F-15 (weighing about four times your average World War Two fighter) shouldn't be able to turn well at all. But it does! In fact, it turns much better than aircraft with far, far lower wingloading. The reason is powerloading.

Powerloading and liftloading cannot be dismissed as easily as you do. Dismiss aspect ratio and the others if you must as "less than secondary," but powerloading is easily the most important factor in turning ability. After all, missiles don't need wings. Liftloading, a good indicator of climbing ability, also greatly impacts turning ability.

I'm no aeronautical engineer. I don't know much about aerodynamics. But I do know enough to know that you're making a big mistake when you calculate turning ability based soley or even just mostly on wingloading.' - Benny Moore
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Offline Bronk

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why spit14 is perked and not 16
« Reply #106 on: December 28, 2006, 07:59:38 PM »
Quote
Originally posted by SgtPappy
Ok back to the XIV's turning.

According to WW's great info, the XIV has a turning circle some 20% worse than the IX - over 55 feet of extra turning circle.

According to RAF tests, the XIV's turning for the 2 planes were 'identical'. Now of course this sentence is far from good, but doesn't it show that the XIV turned so similarly to the IX that a 55' difference would seem quite overdone?

Yes, the XIV MUST turn worse than the IX, but if the test is correct, the XIV must have some quality that allows it to turn so well. My theory is power loading. WW's tests show turning conclusions from turn index. Though those tests are great, the power of an a/c must give better flat, straight forward turning.

'No. By that argument, the F-15 (weighing about four times your average World War Two fighter) shouldn't be able to turn well at all. But it does! In fact, it turns much better than aircraft with far, far lower wingloading. The reason is powerloading.

Powerloading and liftloading cannot be dismissed as easily as you do. Dismiss aspect ratio and the others if you must as "less than secondary," but powerloading is easily the most important factor in turning ability. After all, missiles don't need wings. Liftloading, a good indicator of climbing ability, also greatly impacts turning ability.

I'm no aeronautical engineer. I don't know much about aerodynamics. But I do know enough to know that you're making a big mistake when you calculate turning ability based soley or even just mostly on wingloading.' - Benny Moore


Umm but there is a HUGE difference in thrust between 15 and a XIV.

The difference in thrust between a IX and the XIV is much smaller.

You cant compare apples to oranges.


As a side note you can get close to spit IX turning right, and no where as good turning left.


Bronk
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Offline SgtPappy

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why spit14 is perked and not 16
« Reply #107 on: December 28, 2006, 09:05:07 PM »
Hmm that does make sense sine the Griffon turns the opposite way. Thanks, Bronk.

P.S. Nerf the F4U's turning! Love the plane, though.
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Offline Kev367th

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why spit14 is perked and not 16
« Reply #108 on: December 28, 2006, 11:02:20 PM »
Quote
Originally posted by Krusty
You want an LFIXe, fly the XVI. It's the high-boost later version. It just has a different name because of the US built engine.

As for feeling bad for not having defeated the best of the best? Bah. You won't get much chance in a 109 vs most spits. If you get a kill enjoy it. Doesn't matter which version you killed.


Okey dokey lets clear this up.....

 The VIII and the XVI have exactly the same boost, the XVI was requested at 25lbs but as was said earlier Pyro thought 5 mins of 25lbs boost was too much.
Just to reiterate again - What we have isn't in fact a XVI, the full throttle height of 21k shows it is in fact a mid 1944 LF IXe.
A Merlin 266 fitted to the XVI has a FTH of 22k.

Speeds - Clipped wing birds are slightly faster than their non clipped counterparts. This documented in a scan from another thread of a flight test.

Differences -
VIII - more fuel, full wings, retractible tailwheel.
XVI - less fuel, clipped wings. fixed tailwheel.

All in all they almost equal each other out.

What you have to watch when comparing the XVI to the IX, is which IX you are using.
3 models -
F IX Merlin 61
LF IX Merlin 66
HF IX Merlin 70

Then of course you have clipped, noraml and extended wings.
You have to be sure exactly what configuration the 'IX' is in.

Hub - XII was the first production Griffon Spit, avail way back in 1942 ;) . But as Dan said if it ever appeared it would make the XVI whines pale into insignificance.
« Last Edit: December 28, 2006, 11:09:24 PM by Kev367th »
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Offline Widewing

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why spit14 is perked and not 16
« Reply #109 on: December 28, 2006, 11:26:02 PM »
Quote
Originally posted by SgtPappy

'No. By that argument, the F-15 (weighing about four times your average World War Two fighter) shouldn't be able to turn well at all. But it does! In fact, it turns much better than aircraft with far, far lower wingloading. The reason is powerloading.

Powerloading and liftloading cannot be dismissed as easily as you do. Dismiss aspect ratio and the others if you must as "less than secondary," but powerloading is easily the most important factor in turning ability. After all, missiles don't need wings. Liftloading, a good indicator of climbing ability, also greatly impacts turning ability.

I'm no aeronautical engineer. I don't know much about aerodynamics. But I do know enough to know that you're making a big mistake when you calculate turning ability based soley or even just mostly on wingloading.' - Benny Moore


When we look at Benny's quote, we need to understand that WWII fighters didn't have much thrust. Especially when compared to modern jets like the F-15, which has 58,000 lb of thrust available.

A typical WWII fighter has considerably less than 2,000 lb of thrust to propel it through the air. Some late-war fighters have a bit more, but not much more.

Here's a simple calculation presented by Francis Dean in his book America's Hundred thousand.

375 x prop efficiency (let's use 80%, or .8) x horsepower / speed.

So, we have the Spitfire Mk.XIV doing 358 mph at sea level making 2050 hp.

375 x .8 x 2050 / 358 = 1,718 lb of thrust.  

How about the Spitfire Mk. IX?

375 x .8 x 1660 / 314 = 1,586 lb of thrust.

The Spitfire Mk.XIV has 108% of the Spit Mk.IX's thrust at sea level. just 8% more.

Let's use the F4F-4 for contrast.

375 x .8 x 1,000 / 285 = 1,052 lb of thrust.

Now, look at the F-15 again. It has roughly 34 times more thrust than a Spit14!

That F4F-4 easily out-turns a Spit16, and it does so with only 61% of the Spit14's thrust. So, I ask you; how important is thrust as compared to wing loading and lift coefficient? Not important at all at these levels of thrust.

My regards,

Widewing
« Last Edit: December 29, 2006, 01:03:15 AM by Widewing »
My regards,

Widewing

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Offline hubsonfire

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why spit14 is perked and not 16
« Reply #110 on: December 28, 2006, 11:27:10 PM »
Quote
Originally posted by Kev367th
if it ever appeared it would make the XVI whines pale into insignificance.


That's exactly what I'm looking for. ;)
mook
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Offline Krusty

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« Reply #111 on: December 29, 2006, 01:46:04 AM »
Kev, he was talking about flying a IX. I mentioned the XVI was a higher boost IX. I wasn't comparing to the VIII.

Offline Charge

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« Reply #112 on: December 29, 2006, 05:57:17 AM »
" XII was the first production Griffon Spit, avail way back in 1942  . But as Dan said if it ever appeared it would make the XVI whines pale into insignificance."

I doubt it. The IX is a 42 bird too, and XII matches the 190A5 closely in speed (because it was a JABO hunter) except that at height it is slower and IX needs to go 3000ft  higher before it can match A5's speed. :p.

Only 100 built. Shows the significance the Brits thought it had, so the IX was clearly a better choice for mass production.

But hey I guess you gotta suck your joy from where ever you can...  :rofl

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Offline SgtPappy

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why spit14 is perked and not 16
« Reply #113 on: December 29, 2006, 02:34:30 PM »
So Widewing, what you're saying is essentially that an a/c would need a whole lot more thrust in order to make a turning difference.

Okay, i get it! Hurray!
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Offline Widewing

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« Reply #114 on: December 29, 2006, 07:27:29 PM »
Quote
Originally posted by SgtPappy
So Widewing, what you're saying is essentially that an a/c would need a whole lot more thrust in order to make a turning difference.

Okay, i get it! Hurray!


That, in a nut shell, is it.     ;)

WWII fighters simply did not have enough thrust to make any significant difference in turning ability. Even the most powerful fighters of the time still had to turn nose-down to maintain airspeed and avoid stalling. Modern jets often have a considerable surplus of thrust, allowing them to maintain the tightest possible turn without trading altitude for speed.

My regards,

Widewing
My regards,

Widewing

YGBSM. Retired Member of Aces High Trainer Corps, Past President of the DFC, retired from flying as Tredlite.

Offline Guppy35

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why spit14 is perked and not 16
« Reply #115 on: December 29, 2006, 11:43:09 PM »
Quote
Originally posted by Charge
" XII was the first production Griffon Spit, avail way back in 1942  . But as Dan said if it ever appeared it would make the XVI whines pale into insignificance."

I doubt it. The IX is a 42 bird too, and XII matches the 190A5 closely in speed (because it was a JABO hunter) except that at height it is slower and IX needs to go 3000ft  higher before it can match A5's speed. :p.

Only 100 built. Shows the significance the Brits thought it had, so the IX was clearly a better choice for mass production.

But hey I guess you gotta suck your joy from where ever you can...  :rofl

-C+


Two ways to look at it.  The XII only had the single stage Griffon.  It was in essence produced to stop the hit and run 190s on the south coast of England.  It did that.  

But it wasn't going to be developed further as the two stage Griffon was already in the works for the XIV and the Merlin development finally got around to the Merlin 66 for the medium alt band where the fighting had fallen to from the earlier high alt fights.

In many ways the XVI is comparable to the Spit XII for the low alt war fought in AH.  

But as mentioned with the XIV in the works a single stage Griffon Spit wasn't going to get far with the RAF in terms of development.  But it did keep going for the RN with the Seafire XV and XVII which also had the single stage Griffon VI.

All that being said, I'd like to try an XII in the MA and see what happens in that low alt world we fight in :)
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Offline Kev367th

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why spit14 is perked and not 16
« Reply #116 on: December 30, 2006, 12:23:33 AM »
Quote
Originally posted by Guppy35
Two ways to look at it.  The XII only had the single stage Griffon.  It was in essence produced to stop the hit and run 190s on the south coast of England.  It did that.  

But it wasn't going to be developed further as the two stage Griffon was already in the works for the XIV and the Merlin development finally got around to the Merlin 66 for the medium alt band where the fighting had fallen to from the earlier high alt fights.

In many ways the XVI is comparable to the Spit XII for the low alt war fought in AH.  

But as mentioned with the XIV in the works a single stage Griffon Spit wasn't going to get far with the RAF in terms of development.  But it did keep going for the RN with the Seafire XV and XVII which also had the single stage Griffon VI.

All that being said, I'd like to try an XII in the MA and see what happens in that low alt world we fight in :)


It would get perked.
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Offline SgtPappy

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why spit14 is perked and not 16
« Reply #117 on: January 02, 2007, 08:19:50 PM »
I've also noticed that the Siptfire Mk.IX we have in the game is MH434. According to my research, MH434 was an LF Mk.IX meaning it was equipped with a Merlin 66 engine, like that of the Mk.VIII. Too bad it's equipped with a Merlin 61.
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Offline Oldman731

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why spit14 is perked and not 16
« Reply #118 on: January 02, 2007, 08:20:55 PM »
Quote
Originally posted by Kev367th
It would get perked.

As it should.

What were there...100 of them?

- oldman

Offline Bronk

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why spit14 is perked and not 16
« Reply #119 on: January 02, 2007, 11:19:41 PM »
Quote
Originally posted by Oldman731
As it should.

What were there...100 of them?

- oldman


UMMM

How many Ta 152s were there.
Like what 63?


Bronk
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