P40 Vs all other fighters in Europe

[PAT303]

Two comments on that - one thing I remember reading in pilot interviews about the HF wingtips, is that they disliked the pointed wingtips due to a very negative impact on roll rates. Which again makes me think of the Soviet complaints about the Hurricanes operating near Lenningrad.

I could be remembering this wrong but IIRC LF Spitfires were not doing so well by 20,000 ft due to the engines (Merlin 45M or 50M) critical altitude.

For example this chart for a Spit VB with a Merlin 50M tops out at 350 mph and +15lb boost at just below 6,000 ft. By 20'000 ft it's down to 337 mph and +5 lb boost.

Compare this to a Spit V with a Merlin 45 making 372 mph at 20,000 ft with +9 lb boost.

The MkVII with Merlin 60-70 series was the HF version of the Spit, Spitfire Mk VII Performance.
The V's fitted with Merlin M series engines and clipped wings were LF versions developed to combat the FW190, the M series was purposely developed to give their best performance at low altitude.

 

[Schweik]

I'm well aware of the above, did anything I wrote contradict that?

To clarify - HF Spitfires - good high altitude performance, complaints about roll rate (though I don't know at what altitude)

LF Spitfires, very good at low altitude, not so much at 20,000 ft (contrary to what Shortround6 said)

 

[wuzak]

HF VIII and HF IX had standard wingtips.

Mk.VII had extended wing tips and pressurized cabin, but not many produced.

 

[Shortround6]

You had HF MK VI Spitfires with Merlin 47 engines and long wing tips and you had low flying Spitfires with single stage cropped impeller engines with clipped tips.

You had MK VIIs with two stage Merlins with long wing tips and a few MK VIIIs with long tips (some of which got regular wing tips later.)

You had a bunch of two stage Merlins with standard tips

There were a few MK IXs with clipped wings and there a few MK XVIEs with clipped wings.

The LF and HF referred to the engines, not the wing tips

 

[Schweik]

Actually LF and HF seems to have referred to both wingtips and engines, I would say. At least initially.

I know it was complicated - Spitfire variants are complicated, I was referring to it as part of another point. I think you know what I meant.

 

[wuzak]

Actually LF and HF seems to have referred to both wingtips and engines, I would say. At least initially.

I know it was complicated - Spitfire variants are complicated, I was referring to it as part of another point. I think you know what I meant.

Maybe in the case of the Mk V.

The initial Mk.IXs (with Merlin 61s then 63s) were retroactively renamed F.IX, with the later Merlin 66 version becoming the LF.IX and the Merlin 70 version the HF.IX. Similarly the VIII was to become the F.VIII, LF.VIII and HF.VIII. Few of the LF IVs and LF.VIIIs had clipped wings, and few, if any, of the HF.IXs and HF.VIIIs had extended wing tips.

Also note that the IX was the stop-gap 2 stage Merlin Spitfire, the definitive versions being the VII and VIII, the former intended to be the standard high altitude fighter with extended wing tips, and the latter the standard day fighter with standard tips. Only 140 VIIs were built, earlier versions with the Merlin 64 (F.VII) and later versions with the Merlin 71 (HF.VII). The VII used a pressurized cabin, the Merlins they used were essentially the same as those used in the IX and VIII but with cabin blower. Many VIIs would revert to the standard wing tips.

The VI was a similarly high altitude version of the V using a pressurized cabin and the Merlin 47.

There were no HF or LF versions of the Griffon Spitfires.

The XII was a low altitude version on account of its engine, and would often be fitted with clipped wing tips.

The XIV would have clipped wing tips later in its life as some had wrinkling in wing skins, so the MAP ordered they have the clipped wing tips, though Supermarine said it was unnecessary.

Note that in tests it was shown that the clipped wing tips improved roll rate, but decreased climb rate, ceiling, turning radii and top speeds.

 

[Greg Boeser]

Decreased turn radii? I would have thought increased.

 

[Schweik]

Shorter wings means less wing area therefore higher wing loading. But even an LF (short winged) Spitfire still turned pretty well compared to most other fighters.

 

[Schweik]

My original point, less it be lost in the interesting details about the Spitfire variants, is that a few feet of wing seemed to make a difference vis a vis high and low altitude performance. The longer wings on the spit conferred greater high altitude performance, I think they ended up being dropped because they had such an adverse effect on roll rates (am I right about that?)

This is still getting back to the idea of the relatively small winged P-39, with it's 34' wing span, flying in the Tropics vs Central Asia.

 

[wuzak]

Decreased turn radii? I would have thought increased.

Yes, that's what I meant. Thanks.

 

[Shortround6]

As I mentioned, it is a good illustration of the difference wings can make.

The wing itself didn't change, there were no change to flaps or slats.
From smallest to largest there was under 4% in wing area.

Your major changes are to aspect ratio and the inset to the ailerons.
They tried them from sea level well into the 30,000ft range.
The difference in weight was minimal.

They should provide clues to other wings.

 

[Schweik]

Good point about the ailerons - having the wingtips extended beyond them is a pretty unusual design feature for any aircraft. That may account for the bad roll rate more than just the wingspan...

 

[FLYBOYJ]

Good point about the ailerons - having the wingtips extended beyond them is a pretty unusual design feature for any aircraft. That may account for the bad roll rate more than just the wingspan...

????

I think you'll find that many aircraft have wingtips that extend beyond the ailerons!

 

[Schweik]

Yeah but this is a big more substantial than a faring

 

[FLYBOYJ]

Yeah but this is a big more substantial than a faring

It is - but you'll still find that on the majority of ALL aircraft the WINGTIP extends beyond the aileron.

AND - a wingtip "is not" a fairing.

 

[pbehn]

Good point about the ailerons - having the wingtips extended beyond them is a pretty unusual design feature for any aircraft. That may account for the bad roll rate more than just the wingspan...

Even with its standard wing tips the Spitfires roll rate wasnt bad, its problem was it was facing the Fw 190 which was pretty much the best in class. The extended wing tips were fitted to get to a higher altitude, rate of roll isnt a consideration when you cant even fly straight and level.

 

[Schweik]

It is - but you'll still find that on the majority of ALL aircraft the WINGTIP extends beyond the aileron.

AND - a wingtip "is not" a fairing.

I'd say the HF type wing was the longest 'wingtip' around, by a good margin.

 

[FLYBOYJ]

I'd say the HF type wing was the longest 'wingtip' around, by a good margin.

For a WW2 fighter - possibly.

Gliders have huge wingtips and in some cases put on separately when the glider is assembled for flight.

 

[Schweik]

Correct me if I'm wrong, but gliders are typically made to be very stable and not necessarily for fast rolling right?

 

[FLYBOYJ]

Correct me if I'm wrong, but gliders are typically made to be very stable and not necessarily for fast rolling right?

No - there are many gliders designed for aerobatics and for their wingspans have pretty good roll rates around 90°/sec .