Would a Spitfire with the same wing area as on the Bf 109 have been a good idea or not?

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Holtzauge

Holtzauge

Airman 1st Class
253
349
Sep 8, 2006
Stockholm, Sweden
Most people are familiar with the Spitfire's beautiful elliptical wing and stories about how this enabled it to do tighter turns than the Bf 109.

However, a smaller wing means a faster airplane, and would the Spitfire have been a better fighter if it had had a wing area more like that on the Bf 109?

I recently released a book (made a post in this forum about that here) in which I investigate this, so I have my own ideas about this but what is the forum's opinion?

Would a Spitfire "Mk 1M" as depicted on the right below (same wing area as on Bf 109) have been a good idea or not?


Spitfire Mk I and Mk 1M composite for forum posts with copyright text.jpg
 
Well, the plane would have been faster.
The problem is getting it out of the existing fighter fields with that small wing and with the Merlin III (or early) engine and the fixed pitch propeller.

The Merlin III was rated at 880hp for take-off at 3000rpm and 6 ( 6 1/2) lbs of boost except................................
that with the fixed pitch prop they were running the engine at 6lbs of boost at 2000-2100rpm for take-off. Higher rpm over speed the prop at low speed and actual thrust was lower. Think cavitating propeller on a boat. Actual power may have been somewhere around 600hp?
Now by late 1939 the British were no longer using the fixed pitch props and most (all?) Spitfires that had them had been refitted to at least two pitch props. But now you have to refit all of the older planes with the new smaller wings?
And what can you fit in the smaller wings for guns?
Only 6 .303s?
two 20mm and two .303s?
Can't use the 170 gal ferry tank?
only 120-130 gal? maybe less?

Fitting the later Spitfire radiators into a small wing may have been a bit tricky.
 
Holtzauge said:
Would a Spitfire "Mk 1M" as depicted on the right below (same wing area as on Bf 109) have been a good idea or not?
Click to expand...

Main asset of a fighter was probably sped, not the turning radius.

That wing surgery is similar to what the Yak-3 gotten vs. the previous Yaks (gain about 25 km/h vs. the Yak-9 powered by the same engine), or what Hawker did to the Tempest to arrive at the modern Fury (the 'father' of the Sea Fury). Smaller wing cuts the wing-related part of the drag, that was about 1/3rd of the total drag on a Spitfire Mk.V. So cutting the wing area by a a good 1/3rd - much greater %-age than the two examples mentioned here - and with the caveat that the wing remains at 13% t-t-c at root, in theory cuts the drag by more than 10%.

IMO, the best-case scenario might've been that speed is up by some 30 km/h; worst case - still the 20 km/h speed increase? Problems might've arose at higher altitudes, where having a bigger wing helps a lot, despite the possibility for the smaller wing to be lighter.
Lower drag improves the fuel mileage.

The most interesting scenario might've been once Bf 109F4 and Fw 190A arrive in second half of 1941 - the 'small Mk.V' should've gave them a good run for their money, being a 390+ mph aircraft...
 
Yes, my estimate is also around 20 km/h faster as well.

But I also estimate a slightly better climb speed (about 1 m/s or 200 fpm) at low to medium altitudes: This is because if you reduce the wing size, the weight goes down as well.

Then for sure: At higher altitudes the big wing becomes an asset again. However, because the weight goes down as well, this to some extent lessens the effects of reducing the wing area, and according to my calculations, the cross over point is quite high: All of 8.5 km (27,900 ft) in altitude, and at anything below that then the Spitfire Mk 1M performs better than the original.

But as you both point out, fitting the guns and other equipment in there would have been a problem. However, the Bf 109's NACA 2R1 airfoil actually has lower drag than the Spitfire's NACA 22 series airfoil even if it is thicker so you would not need to lessen the wing thickness proportionally to the wing size reduction if you were to change the wing profile as well.
 
Depends on what you mean by "performs better." Might be a tad faster, but top speed was VERY rarely used in combat unless the aircraft was diving to attack or escape.

Level flight at top speed was a very rare thing. It tended to result in engine difficulties if kept up for very long. Even today, go run an engine at full speed for an extended time and decide of YOU would like to try that 500 miles inside enmy territory when the same engine is your sole means of getting home.

The 400 mph fighters mostly cruised around, even in combat areas, at 270 - 320 mph, nowhere NEAR their top speeds. Radial fighters cruised even slower, sometimes less than 200 mph, mostly to save fuel. An F8F Bearcat can cruise at 350 mph, but you run a LOT of gasoline through it to do that. Many times, they were far away enough from the carrier that they they simply didn't HAVE the gasoline to go that fast and still get back to the carrier, so fuel was primary consideration for escorts and Naval patrols.

Typically, in WWII, combat ws joined at 300 mph or less and only got faster when headed downhill for some reason. After the fight descends to within several hundred feet of ground level, that descent is not possible and you are left with level or climbing combat speeds. NOBODY flew around at full power for very long. Yes, you can fly around a maximum continuous power settings, but your range will be a LOT shorter than if you flew wisely. If you fly at max continuous, you will not be able to escort to Berlin and back.

According to most WWII pilots I have spoken with (over 100) top speed was rarely an important number unless you were trying to escape getting killed by a superior attacking force. Think 3 or 4 fighters going after YOU after you got separated from your unit. If that happened, flight at full power away from the attackers was preferable to death and was used to stay alive. Otherwise, "combat speed" was used, which was basically rated military power, which is not the same as "war emergency," or whatever term for it was used locally. The intent was to perform well, but not to grenade the engine trying to get the absolute best from your mount.

So, yes, top speed was a factor, but mostly in order to escape when required. You didn't need it to attack MOST of the time. You might need it EVERY time you had to flee.
 
Last edited:
Shortround6 said:
Well, the plane would have been faster.
The problem is getting it out of the existing fighter fields with that small wing and with the Merlin III (or early) engine and the fixed pitch propeller.

The Merlin III was rated at 880hp for take-off at 3000rpm and 6 ( 6 1/2) lbs of boost except................................
that with the fixed pitch prop they were running the engine at 6lbs of boost at 2000-2100rpm for take-off. Higher rpm over speed the prop at low speed and actual thrust was lower. Think cavitating propeller on a boat. Actual power may have been somewhere around 600hp?
Now by late 1939 the British were no longer using the fixed pitch props and most (all?) Spitfires that had them had been refitted to at least two pitch props. But now you have to refit all of the older planes with the new smaller wings?
And what can you fit in the smaller wings for guns?
Only 6 .303s?
two 20mm and two .303s?
Can't use the 170 gal ferry tank?
only 120-130 gal? maybe less?

Fitting the later Spitfire radiators into a small wing may have been a bit tricky.
Click to expand...
Could the wing have been easier to build?
 
GregP said:
Depends on what you mean by "performs better." Might be a tad faster, but top speed was VERY rarely used in combat unless the aircraft was diving to attack or escape.

Level flight at top speed was a very rare thing. It tended to result in engine doifficulties if kept up for very long. Even today, go run an engine at full speed for an extended time and decide of YOU would oike to try that 500 miles inside enmt territory when the same engine is your sole means of getting home.

The 400 mph fighters mostly cruised around, even in combat areas, at 270 - 320 mph, nowhere NEAR their top speeds. Radial fighters cruised even slower, sometimes less than 200 mph, mostly to save fuel. An F8F Bearcat can cruise at 350 mph, but you run a LOT of gasoline through it to do that. Many times, they were far away enough from the carrier that they they simply didn't HAVE that gasoline to go that fast and still get back to the carrier, so fuel was primary consideration for escorts and Naval patrols.

Typically, in WWII, combat ws joined at 300 mph or less and only got faster when headed downhill for some reason. After the fight descends to within several hundred feet of ground level, that descent is not poissible and you are left with level or climbing combat speeds. NOBODY flew around at full power for very long. Yes, you can fly around a maximum continuous power settings, but your range will be a LOT shorter than if you flew wisely. If you fly at max continuous, you will not be able to escort to Berlin and back.

According to most WWII pilots I have spoken with (ovre 100) top speed was rarely an important number unless you were trying to escape getting killed by a superior attacking force. Think 3 or 4 fighters going after YOU after you got separated from your unit. If that happened, flight at full power away from the attackers was preferable to death and was used to stay alive. Otherwise, "combat speed" was used, which was basically rated military power, which is not the same as "war emergency," or whatever term for it was used locally. The intent was to perform well, but not to grenade the engine trying to get the absolute best from your mount.

So, yes, top speed was a factor, but mostly in order to escape when required. You didn't need it to attack MOST of the time. You might need it EVERY time you had to flee.
Click to expand...

But if top speed was "VERY" rarely used and "NOBODY" flew "NEAR" it and it consumed such a "LOT" of fuel, why was it at the top of the list on both the British and German procurement specifications at the time? Why did both Supermarine and Messerschmitt chase top speed with the Spitfire and Bf 109? What were they missing?

Why did they insist on putting bigger and bigger more fuel guzzling engines on their airplanes if top speed was not important? And yes, bigger engines do improve climb rate as well, but top speed was at the top of the list. It actually moved there from being of lower priority than climb, but both the Luftwaffe and RAF were chasing top speed in these designs. They topped their wish list with it.

Seriously: Why the longwinded explanation that most pilots did not fly around at top speed all the time and and that top speed is rarely used? You even list why it (top speed) is important yourself: Because you need it to either attack or disengage. Of course you don't do that all the time, but when you do want to catch an opponent or escape, you want every km/h or mph you can squeeze out of your ride. In addition, reducing the wing size on the Spitfire will also make it lighter and climb faster.

Not sure where you are going with this: The premise here was if reducing the wing size on the Spitfire Mk I would make it better worse aircraft compared to the Bf 109E. Everyone here seems to agree it would have made it faster, but you make a long winded argument that top speed is unimportant because it's so rarely used? Que?
 
Admiral Beez said:
Do we have to keep the elliptical shape? Though still larger than the Bf 109's 16 sqm wing area, the more conventionally winged Supermarine Spiteful had a significantly smaller wing area (20 sqm) to the Spitfire (22.5 sqm). Maybe start there and shave off 4 sqm.

View attachment 857538
Click to expand...

Yes, the main driver of drag on the wing at high speed is simply the wetted surface: If you can reduce that then your drag goes down. And about the elliptical shape: Since they built in wash-out into the Spitfire's wing, the lift distribution was not elliptical anyway, and the main advantage the Spitfire held over the Bf 109 was in wing- and span loading, not that the Oswald factor e was any better, and the double trapezoidal of the Spiteful should be quite efficient as well.
 
Top speed is useful to know or makes a good bench mark even if top speed is rarely used in combat.
Top speed is achieved flying dead level, un banked and after a certain period of acceleration.
However a plane that can hit 350mph instead of 320mph will have more surplus power available when flying at 290-300mph than the 320mph airplane. Or just about any other speed one would care to select.
The extra power can be used to climb, or to turn when the other plane can only flight straight. Or to maintain a turn at lower speeds better than the slower plane.

This may not apply to all planes but the difference in speed is an easy place to start looking at other details.

Best climb is often done at 120-170mph depending on plane. Best climb is power to weight after you take out the power needed to fly at best climb speed, which is 10-20mph faster than the cross over in the drag curves to give a little margin for stability.

But top speed is just the 1st thing to look at, not the only thing. A P-40 is faster than Zero but it is a lot heavier so at 280-300 mph it may not have much, if any, more extra power than the Zero.
 
For sure, speed is not everything but given a choice of an aircraft that has a top speed of 320 or 350 mph I think most would go for the latter. You have to remember as well that a Spitfire Mk IM with a wing about the same size as that on the Bf 109 E would instead of only being on par with the Bf 109 at typical Battle of Britain raid heights been about 20 km/h faster. That's a huge advantage and allows you to dictate the fight: You can either attack or disengage. Same goes for the P-40 versus Zero: The P-40 is faster at all heights.

Of course you can always construct a scenario in which a slower aircraft wins over a faster, such as a Hurricane over a Bf 109 or a Zero at a higher altitude than a P-40, but a faster aircraft will generally have more options open, so I would still guess that a majority of WW2 pilots would go for a Spitfire Mk IM rather than the vanilla Mk I. But I could of course be wrong, and that is the subject of this thread: Would a Spitfire with a smaller wing have been better or not?
 
Reluctant Poster said:
The first Spitfire Mk III had shiortened wings. It was not a success and was refitted with standard wings.
Click to expand...
Wings on the Mk.III were just the clipped Mk.1 wings, not the new wings' type. Basically the same wings were very successful on many Spitfires produced.
Dowding objected that such a Spitfire will look too much like the Bf 109, leading to the friendly fire accidents. Wing loading was also greater, especially now that the engine in the nose is heacier, and the wing area is lower. So they retrofitted the normal wingtips.
 
Reluctant Poster said:
The first Spitfire Mk III had shiortened wings. It was not a success and was refitted with standard wings.
www.destinationsjourney.com

Supermarine Spitfire Mk. III - Destination's Journey

Photos of the Supermarine Spitfire Mk III, the first redesign of the basic Spitfire with improved undercarriage, new wing and canopy
www.destinationsjourney.com www.destinationsjourney.com
Click to expand...

Just shortening or clipping the wings like on the Mk III makes the aspect ratio worse so not the same thing as building a smaller elliptical wing like on the the Mk IM example.

Then secondly, there were a whole lot of other things going on with the Mk III other than the shortened wing, and that the Mk V was considered good enough so there was no need to pursue the Mk III:

https://www.key.aero/article/spitfire-mkiii-forgotten-fighter
 
tomo pauk said:
Wings on the Mk.III were just the clipped Mk.1 wings, not the new wings' type. Basically the same wings were very successful on many Spitfires produced.
Dowding objected that such a Spitfire will look too much like the Bf 109, leading to the friendly fire accidents. Wing loading was also greater, especially now that the engine in the nose is heacier, and the wing area is lower. So they retrofitted the normal wingtips.
Click to expand...

Beat me to it! ;)
 
Holtzauge said:
Then secondly, there were a whole lot of other things going on with the Mk III other than the shortened wing, and that the Mk V was considered good enough so there was no need to pursue the Mk III:

https://www.key.aero/article/spitfire-mkiii-forgotten-fighter
Click to expand...
Mk.III was just fine, and it offered a lot via it's earodynamic improvements, increased fuel tankage and the engine it was using.
Mk.V was indeed considered as good enough - a mistake that haunted the RAF people a good deal in 1941-42.
 
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