Bf-109 vs Spitfire vs Fw-190 vs P-51

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Njaco said:
I'm no expert but I believe that was for carrier Spitfires (Seafires) - space concerns.
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Chris
clipped wings were configured for low-altitude performance, there would be an increase in roll rate at the expense of lift. These would typically be annotated as low-altitude birds eg LF Mk Vb, LF Mk IXe.

Lift is what you need when you're carrier-borne so there was no question of clipping the wings, the earliest sea-going Spitfires (not Seafires) had their wing tips removed and stowed in the cockpit, the only example I can think of right now being the Eagle and Wasp carriers ferrying Spitfires to within flying-in range of Malta. The Seafire eventually had folding wings to deal with the space issue.

Below: Sitting on Wasp's flight deck immediately after being hoisted on board, this Spitfire V still has the sling in position on the forward fuselage and its wing tips in the cockpit. USN

Bottom: A Seafire III showing the method of wing folding introduced with this version. Price
 

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The roll rate of the clipped Spits were faster.

Made it more matched against Fw 190.

The Fredrich was certainly good against the Mk V.

Why the RAF went crazy over the 190 when the Fred was also better....dunno.

Maybe it was a novelty thing.

Naval Seafires were poor naval aircraft....totally illsuited to carrier operation.
 
drgondog said:
Of the 4 (109, Spit, Fw 190 and P-51) the 51 was the cleanest and the 109 was the draggiest.
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This latter statement based on what..? Compare top speed with the power required... The IX, AS/D versions of the 109 and the P-51 had approx. the same amount of horsepower. The Mustang was generally the fastest on the same power (except 109K, which was actually a tiny bit faster), about 10-20 km/h faster than the 109s.. the Spit IX was about 60 km/h slower than the Mustang, with the same powerplant..

So I wonder, if your thesis is correct, how come the supposedly draggiest airframe with the same amount of power be also one of the fastest ones..?
 

With regard to the loss rates the RAF were in the reverse situation to the Battle of Britain. Flying over the channel put the spitfire at a disadvantage, any hit to the fuel or cooling meant probably the aircraft was lost. Additionally both sides knew the game they were playing, the RAF were trying to cause losses to the LW strength, the LW therefore , when they had the choice only engaged when they were in a position of advantage., like height or numbers. For the RAF giving chase to LW planes could mean being led into a trap or running out of gas.
 
Milosh said:
How can the paint be draggy when it was a finer grain than American paint? That means it not as orange peely as American paint.
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Of course, different paints had different grain sizes. Nothing surprising. Moreover Mustang wing was covered with different slices of paint, even hiding rivets heads and sheet junctions. Then highly polished ans shined. This is the normal laminanarity condition; you can loose it for every mosquito's sh*t on your surfaces.

How can the radiators be draggy when they had a boundary layer separator?
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Na und? And what your separator does, to reduce drag?

Why would the exhaust stakes be draggy?
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Maybe more optimised? Better diffusor angle for the stream? Anyway it's far from being the sole reason for the Mustang to have the lowest Cd from all WW2 fighters. There might by an extended amount of negligeable details in itself, that taken together could make the difference.
For instance the 109's external carburettor air intake was twice as draggy as early LaGG-3/Yak-1 wing one and full 3-4 times with later improved LE lips/ ducts ones.


Only the G-6 and G-14 had noticeable bulges.
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From TsAGI studies, the squared 109 bulge could have been easily improved, as other details. Anyway we still talk about it:

http://www.ww2aircraft.net/forum/aviation/yak-1-7-9-vs-bf109g2-24856-3.html#post674614

Regards
 
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I think that somethings may be being confused here.

OVERALL drag between a Mustang and a 109 may very well be similar.
We would have to compare specific models at the same altitude and know the power output for both engines at that specific altitude.

However, even if the 109 is equal or even slightly faster than the Mustang using the same power it is still a "dragger" airframe because it is a smaller airframe. The Mustang with it's bigger wing and larger fuselage is more streamlined for its size. THe larger size allows it to carry the extra fuel and heavier weight of armament. I don't want this to veer off into tangent but I think we can all agree that that the Mustangs .50 cal MGs and ammo weighed more than the 109 normal internal armament.
So you have a small but higher drag airframe (the 109) vs a larger but lower drag airframe (Mustang) giving the same TOTAL drag.

As an example the Lockheed Orion transport has a drag coefficient similar to a P-47 even though it is a 6 passenger airliner.
Drag coefficient measure how streamline a plane is for it's size. the coefficient has to multiplied by the planes size (usually wing area) to get profile drag. this doesn't include induced drag. At least I don't think it does but those with aeronautics degrees ( or more knowledge) are free to correct me.
Looking at the F2A-3 it has a lower total drag (profile) than an F4F-3 not because it is more streamlined but because it used a much smaller wing. At 6.27 sq ft of 'flat plate area" for the Buffalo compared to 6.58 sq ft for the Wildcat the difference isn't great but at 209 sq ft of wing to 260 sq ft of wing the Buffalo has a hard time claiming it is a lower drag airframe.
 

Shortrounds basic answer is correct. The Mustang wetted area is about 50% greater than the 109 and 6% greater than the Spit and 16%greater than the Fw 190D-9.

From Hoerner: At 380mph, 22,000 feet at 6700 pounds gross weight, 1200 Hp:

Building up all the drag factors, applying Thrust calculated with 140 pounds of exhaust thrust at 380mph and propeller efficiency of .85 and getting total drag yielded:

The Drag Area of the 109G is approximately 6.2 sq ft with Cd of .036 at that speed and altitude.

The total wetted area of the 109G, according to Hoerner, is 590 square feet. Also according to the example calculations using the 109G Hoerner's calculated CDwet = .0105. (Divide Drag Area by Wetted Area). Compare against the following values derived from Flight and Wind Tunnel tests:

The tables in Lednicer's WWII Fighter Aerodynamics present the following at ~360kts, 15,000 feet.
1. Spit IX Drag Area = 5.4 sq Ft, Wetted Area = 831.2 sq ft, CDwet = .0065
2. P-51B Drag Area = 4.61 sq ft Wetted Area = 874..0 sq ft, CDwet = .0053
3. P-51D Drag Area = 4.65 sq ft Wetted Area = 882.2 sq ft, CDwet = .0053
4. Fw 190A-8 Drag Area=5.22 sq ft, Wetted Area = 735.0 sq ft, CDwet = .0071
4. Fw 190D-9 Drag Area=4.71 sq ft, Wetted Area = 761.6 sq ft, CDwet = .0063

The data Lednicer presented include (but not limited to) the following
Spitfire - "the Development of the Spifire and Seafire". Journal of the Royal Aeronautical Society, Vol 51, April 1947.. plus various flight tests including "Measurements of the flying Qualities of a Supermarine Spitfire VA Airplane, NACA WR L-334, September 1942.

Mustang = "High Speed Wind Tunnel Tests of Models of four single engine fighters (Spifire, Spiteful, Attacker and Mustang" Staff of RAE High Speed Wind Tunnel Tests - Parts 1-5 Aeronautical Research Council R&M No 2535, 1951

Mustang - Correlation of the Drag Characteristics of a Typical Pursuit Airplane Obtained from High Speed Wind Tunnel and Flight Tests" NACA Report 916, 1948

Lednicer's VSAERO model very closely approximated the values derived from full scale wind tunnel tests. These values are derived at 360kts, for Reynolds number at 15,000 ft.
 

All good stuff with one (long) comment.
The Total Drag = Parasite Drag + Vortex Drag + Lift Dependent Drag + Compressibility Drag

Parasite Drag has components of surface imperfections (paint friction/gaps, etc) and is applied to the wetted area. Parasite drag has components of 'bumps', antenna, open whell wells, turrets, etc and are calculated independently, summarized and applied against wetted area to derive CDp.

Vortex Drag - contains viscous components including increases in skin friction and pressure drag associated with increasing changes to angles of attack. These occur because the increased velocities on the upper surface of the wing lead to higher shear stresses and adverse pressure gradients - with corresponding increases to pressure drag. This is where early analysis gets hairy because it also includes such effects as nacelle/pylon interference, changes in trim drag due to angle of attack, change in drag due to engine power effects (either inlet or exhaust), wing leading edge geometry, camber, thickness ratio, etc)... these factors are applied as function of wing area to derive CDv.


Lift-Induced Drag - contains the inviscid components associated with lift and include the commonly phrased 'Induced Drag" with well known components of CL/AR/e plus twist factors of drag at zero lift. It is further modified by a factor for added lift dependent drag caused by modification of spanwise lift distribution caused by the wing/fuselage combination. This is applied to area of wing also to derive CDi.
 

The clipped wing was more to achieve a faster roll rate - and yes became more like a trapezoidal wing planform. However the trailing edge was still 'elliptical in nature. It is an interesting question in that what does 'more like Trapezoidal or more less elliptical' mean?

The Spit achieved a higher Mach number in a dive due to the thinner wing.
 
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Thank you. Many books only mention one or two of the components and not all.
While I may not be able to do the math I would at least like to understand some of the factors that go into it.

It may not be easy to get a small plane to go fast with a certain amount of power, it is even harder to get a plane carrying a much larger payload to go as fast on the same power.
 
Kurfürst said:
T .. the Spit IX was about 60 km/h slower than the Mustang, with the same powerplant..
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The Mustang was definitely faster than a Spitfire, but even though they both used the Merlin engine there were differences in propeller gearing, boost levels and supercharger critical altitudes, that make direct comparisons tricky.
 
RCAFson said:
The Mustang was definitely faster than a Spitfire, but even though they both used the Merlin engine there were differences in propeller gearing, boost levels and supercharger critical altitudes, that make direct comparisons tricky.
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True if you wish to state that the Mustang was "xx mph" faster than the Spitfire at "yy,000 feet".

Not as tricky when the flight test data reports max speed for the same boost/rpm as that configuration and flight envelope is optimized for both ships to set an upper limit for a specific combat version/model number
 

Shortround - Preliminary Design is the world of a.) applicable theory and b.) go look up the fudge factors -

Math works well and consistently in the world where the theory behind the model is linear and applicable. The Fudge factors are empirical design parameters (like wing/fuselage interference drag for a specific span to fuselage diameter and aspect ratio, or drag due to aileron gaps or blisters or ?? ) where you literally go to your own set of bibles/wind tunnel data in the aero biz and scan the charts...
 



Is there a limit for a propeller driven aircraft obviously they cant go supersonic, but for example Napier claimed that they had produced 5,500 hp (4.100 kW) at 45 lb/sq in boost in a test, would a Tempest or Sea Fury or any monoplane for that matter be substantially faster and controllable with that sort of power or do they reach a limit of physics like steam engines.
 

I think prop planes are starting to run into a barrier around 500 mph. Rare Bear, the fastest prop race modified plane, a F8F, did 528 mph with a 4000+ hp (probably close to 5000hp) engine. This is only about 40 mph faster than the fastest WWII prop jobs, the P-51H, Ta-152H, P-47M, et. al., with much less power. The P-47M, the most powerful WWII single engine aircraft, had 2800 hp at 33k ft.
 
I think it also relevant to note that the Spit IX, when introduced in June '42 hada top speed at 20K of around 405 MPH. The G-2, with a slightly less powerful engine, but introduced at around the same time, had a top speed at that altitude of around 385 MPH. In 1943, the Spit IX was progressively introduced to the uprated versions of the Merlin, giving it a top speed of around 414 MPH for some of its subtypes. The G subtypes eventually gave way to the Me 109K, introduced in September 1944, by which time the Spit IXs were completely superseded. The Me109K had a top speed of around 427 MPH at that 20K standard, but are we making a fair comparison here....the K was more than two years younger than the spit subtype we are comparing it to, and I believe3 had ceased production by that time.
 

Well the tupolev bear did 545 to 575mph (depending where you read) but had around 60,000SHP it seem to me as if an operational single seat single engined plane has a limit of about 500mph as you say. Considering rare bear had a bigger engine no armament and was specially prepared for racing it was not substantially quicker than the original bearcat
 

The merlin had a swept volume of 27 Litres while the Me 109 had a swept volume of 34 to 36 litres It wasnt until the 37 litre griffon variants came in to sevice that the engines of both were of approximately the same size.
 

Please keep in mind the altitudes the speeds were achieved at. Reno is about 4400ft above sea level plus what ever hight the planes are above ground level.
The top speed of the WW II and after service Bearcats was achieved at around 20,000ft or higher. Much thinner air means much less drag.
Sea level speed for a Bearcat was around 382-387mph depending on model. Put that together with a Military rating about 400hp lower at 20,000ft than at sea level and I think we can see were the extra HP of the Rare Bear is going or why it is needed at around 5000ft.
 
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