Corsair vs. BF 109G,K or FW 190's

[Glider]

Thanks for this

 

[davparlr]

The point being the P-51D does not seem having '23 – 27 mph advantage' over any of these aircraft.

At least, the 354mph achieved by the P-51D/67" vs. the 352mph achieved by the G-14 is not ~25 mph difference in my book, more like 2 mph (though the 109 achieves it with slightly more power available, so on even footing, the Mustang is probably a bit better, say 360-365).

I got the info from this site which looks authentic including the identification of the aircraft number. In addition, two other sources I have and trust agree to the data shown in this flight test. The P-51D shows 375 mph at SL using about 1630 hp. I think my comments are good.

http://www.wwiiaircraftperformance.org/mustang/p51d-15342-level.jpg

How come, the P-51D was introduced what, June-July 1944, the 109K in October the same year. 'Much later' - like what, four months...?

The P-51D was introduced into the 8th AF in March '44. The Bf-109K was introduced in November, '44. Six months in WWII during this time was a generation of aircraft development. In the summer and fall of 1944, a whole family of aircraft with much greater performance over the mainstay of WWII aircraft, was introduced on both sides. These include Fw-190D-9, Bf-109K, F4U-4, P-47M/N, P-51F (later H), Ta-152H, and others.

The P-51H, with it`s performance apprx. on the level of the 109K, appeared in when, something like August 1945 on operation, some 10 months after the 109K (I am not sure about the 51H ever seeing combat in WW2)..?

The XP-51F, the predecessor of the H, flew in Feb. 44. Unlike Germany, who was desperate to stop the hordes of P-51s, P-47s, B-17s, B-24s, and Brit planes, with advanced aircraft, the US, whose aircraft performance was adequate and the quantity was overwhelming, did not expedite new models. Had the need arose, there is no doubt that a P-51H or the similar P-51F could have been available in the fall of '44.

Still, the 355 mph or so achieved by the P-51D in normal condition at 67" does not seem to me higher than 370 mph achieved by the 109K at 1.8ata (alternate comparison can be made at similiar power at 81"/1.98ata, at comparable power ie. 379/377mph. Again not much of a difference).

My multiple sources show that the P-51D was capable of 375 mph at SL at about 1640 hp. The Bf-109K had 1800 horses available and could not achieve that (and my source for that is not Mike Williams site).

PS : You might want to add the 1.98ata climb rates into your climb rate comparison to keep the playing field even, also I can`t understand why the F4U4 climb figures you are showing are so much higher than every other Navy document shows.

Ie.

SL
Your F4U-4 4800 vs 4400 reported for F-4U4 at 12450 lbs, at 70", inOctober 1944 specs.

10k
Your F4U-4 4800 vs ~4300 reported for F-4U4 at 12450 lbs, at 70", in October 1944 specs. (revised and superseed to 4000 fpm in April 1945)

20k
Your F4U-4 3800 vs 2980 reported for F-4U4 at 12450 lbs, at 70", in October 1944 specs.
(revised and superseed to 3270 fpm in April 1945)

30k
Your F4U-4 2000 vs ~1400 reported for F-4U4 at 12450 lbs, at 70", in October 1944 specs

Your data is very significantly higher than the official US performance data reported in October 1944. Why?

I don't know. While the data I referenced looks authentic and professional and states that it is flight test data (no tail numbers however), I have researched a lot and have not come up with support data for those values. Since I do not like depending on sole source data, especially when other data is available, I must withdraw my comments referencing F4U-4 climb rates.

 

[davparlr]

24 April 1944

Flight Tests on the North American
P-51B-5-NA Airplane, AAF No. 43-6883

Maximum speed at sea level (67" Hg. manifold pressure 3000 RPM) - 371.0 MPH

15 June 1945

Flight Tests on the North American
P-51D Airplane, AAF No. 44-15342

Maximum speed at sea level

War Emergency power (3000 RPM and 67") 375 MPH
Military power (3000 RPM and 61") 364 MPH
Normal Rated power (2700 RPM and 46") 323 MPH

Flight test of the P-51B in May '44 with 150 gas shows a airspeed at SL of 374 mph. The number I gave before of 386 mph was on manufacturer estimates and is not as reliable as flight test.

http://www.wwiiaircraftperformance.org/mustang/eglin-p51b-level.jpg

 

[davparlr]

What a surprise, Mike William's site again - thought you guy knew better by now not to use his site as reference for German a/c performance.

The FW-190 Dora-9 has a climb rate of 4,400 ft/min, the Bf-109K-4 over 5,000 ft/min ! Even with the thin experimental DünblattSchraube the Bf-109 K-4 boasted a 4,800 ft/min climb rate!

As you know, I always insist on having the best data in my data base. All the numbers I showed on the Fw-190D-9 and airspeed for the Bf-109K were based on data you provided. Unfortunately, I do not have any data from you on climb for the Bf-109K, so the only data I could use was from Mike Williams site and this particular data (but not most at Mike's site) may be a bit suspect. I would be glad to update my data base to better data if you could give it to me.

PS: Have you got time to climb figures for the F4U-4 as-well ?? I'd like to see wether the F4U-4 is able even to beat the Dora-9 to 10km.

Unfortunately, I do not have this data. I will try to find some.

And about your assumption on the RAF test-pilots, well thats all it is, an assumption.

Kurfürst and I have both provided more than enough evidence as proof that the British test-pilot flying the 109 didn't push it beyond the deployment of the slats.

Let me sum it up here:

1.) The British test-pilot makes the comment: "The 109 being embarrased by the opening of its slots", this alone being a clear enough sign that he wasn't pushing past slat deployment.

2.) During the British comparative testing the test-pilot didn't even accomplish to turn the 109 as tightly as the FW-190 or P-51, eventhough the Bf-109 clearly always out-turned the FW-190 P-51 in German Soviet comparative testing.

3.) Several German experten make it clear that green 109 pilots didn't push past slat deployment, the slight notch and loud bang sometimes heard convincing the green pilots that they were right at the limit.

4.) The 109E had frequent problems with slat failure, being enough reason for even a German experten to choose not to push the 109 to the limit in turns because of their past experience with the Emil. The British test-pilots (if not having experienced troubles with the slats on the Emil and therefore being concerned when testing later versions) had themselves heard nothing but bad news about the slats, seeing that a few Westlands crashed because of slat failure and that this had led o hem being locked shut in flight, given more than enough reason for British pilots to be vary about the slats.

You haven't changed my mind. It is just inconsistent with the nature of flight test pilots. And my impression of British pilots is that they are a daring lot.

 

[Crumpp]

http://www.wwiiaircraftperformance.org/mustang/eglin-p51b-level.jpg

According to this graph, the data is recorded at an isobaric altitude in May 44. It is the pressure altitude and is not corrected for density. At higher altitudes our TAS increases as we factor in the SMOE.

May is a high density alitude month generally speaking and the chart clearly states it is not corrected to STO.

This means our airplanes level speed performance in this graph will be faster than it will be under STO.

All the best,

Crumpp

 

[Crumpp]

These graphs represent performance of an aircraft using the manufacturer's data on the type in a standard atmosphere. All data was compiled and calculated under the NACA Standard Atmosphere of 1922 using KEAS so altitude conversion is not necessary. Altitude effects will shift the curve, changing the specific velocity in KTAS performance occurs but will not effect the shape or general conclusions.

Compressibility effects were applied adopting a standard of 200KTS and 10,000feet. Position error corrections were taken from the manufacturers supplied data along with IAS data.

Here is the maximum sustainable load factor for an FW-190A8 in clean configuration, overloaded fighter variant:




Here is the P51D in clean configuration, overloaded fighter variant:




At TO Weight, the FW-190A8 holds a slight advantage in Nzmax sustainable in the medium and low velocity realms. At higher velocity where the P51D becomes the faster aircraft, the P51D holds a slight advantage in Nzmax sustainable. Neither aircraft has an advantage that would be noticeable in the air. Pilot skill would make the difference.

What is clear is that these aircraft in like configuration are very much equals in sustained turning performance.

I have other configurations and aircraft types calculated too.

All the Best,

Crumpp

 

[davparlr]

According to this graph, the data is recorded at an isobaric altitude in May 44. It is the pressure altitude and is not corrected for density. At higher altitudes our TAS increases as we factor in the SMOE.

May is a high density alitude month generally speaking and the chart clearly states it is not corrected to STO.

This means our airplanes level speed performance in this graph will be faster than it will be under STO.

All the best,

Crumpp

Several believable flight test show the P-51B was capable of SL speeds of over 370 mph to up 388 mph. Actually, I have to withdraw my previous comment about the 386 mph being a manufacturers speed when these show actual test results.

http://www.wwiiaircraftperformance.org/mustang/p-51b-24771-level-blue.jpg

 

[FLYBOYJ]

The British test-pilots (if not having experienced troubles with the slats on the Emil and therefore being concerned when testing later versions) had themselves heard nothing but bad news about the slats, seeing that a few Westlands crashed because of slat failure and that this had led o hem being locked shut in flight, given more than enough reason for British pilots to be vary about the slats.

Again Soren, you're assuming or imagining things - I challenge you to show any evidence that any Brit who flew Lysanders to be "vary" of the LE slats. They were locked down because of maintenance constraints and the aircraft performed well with or without them.

Off topic but for you Lysander fans...



View: https://www.youtube.com/watch?v=CRYCx_G25ro

Here's one being flown today - watch the clip, on take off and landing you could see the slats deploy. If these items were such a hazard, its amazing 60 years later they are being used on the last flying examples.


View: https://www.youtube.com/watch?v=MGVebC2SJsM

 

[Glider]

Which reminded me, I should have thought of it earlier.

 

[Crumpp]

Several believable flight test show the P-51B was capable of SL speeds of over 370 mph to up 388 mph. Actually, I have to withdraw my previous comment about the 386 mph being a manufacturers speed when these show actual test results.

Certainly the performance is believable. All aircraft performance is a percentage range over a mean average. The manufacturer only reports the average and not the optimistic or pessimistic examples.

Without more information on this particular flight test it is simply impossible to make any conclusions.

However we can certainly conclude that North American was privy to all of the data on their own design when they reported the performance averages and percentage range to the USAAF.

They were locked down because of maintenance constraints and the aircraft performed well with or without them.

Do you have proof that the slats where locked down? I find this very unusual as it would alter the handling and performance of the aircraft considerably. It would alter the design drastically.

All the best,

Crumpp

 

[Crumpp]

Interesting system on the Lysander. It is a modification of Handley Page automatic slats:

The last of the preflights are then completed before you sit down in the cockpit; this entails checking the inner slat movement-that the flaps are moving with them and that both sides move equally. The outer slats are aerodynamically actuated and are totally independent of the inner slats and of each other. The inner slats are also aerodynamically actuated but are linked so that they operate together. These inner slats also operate the flaps; when the slats deploy, the flaps are automatically extended.

Clandestine warrior Flight Journal - Find Articles

I look forward to the details on these slats being locked shut.

All the best,

Crumpp

 

[FLYBOYJ]

Do you have proof that the slats where locked down? I find this very unusual as it would alter the handling and performance of the aircraft considerably. It would alter the design drastically.

All the best,

Crumpp

I've been trying to find the source of the information regarding the disabling of the Lysander's LE slats, and if I remember right the article stated this involved Lysander I and IIs and it was done pretty early in its career. As far as disabling the system, I doubt it would do nothing but raise the stall and landing speed by a few knots - there have been many aircraft where because of modifications or problems in the field high lift devices were removed or disabled or limitations placed on flap settings.

 

[FLYBOYJ]

Getting close - from the Canadain War Museum..

"When the serious fighting got going it was found to be impractical, as it was too big, too heavy and too vulnerable and needed massive support of fuel and mechanics. Lysanders were replaced by small light planes such as the Piper L-4 Cub."

 

[drgondog]

The P-51D was introduced into the 8th AF in March '44. The Bf-109K was introduced in November, '44. Six months in WWII during this time was a generation of aircraft development. In the summer and fall of 1944, a whole family of aircraft with much greater performance over the mainstay of WWII aircraft, was introduced on both sides. These include Fw-190D-9, Bf-109K, F4U-4, P-47M/N, P-51F (later H), Ta-152H, and others.




QUOTE]

Dave - I know that the 4th FG and 355th FG received their first P-51D-5's just after D-Day.. I am pretty sure none of the 8th FC received a 51D before May. IIRC they arrived in Britain in May but didn't reach operations until late May or June

Of course I have been wrong before.

I'll check with Ted Damick to see what his records have for the first D-5 to arrive in ETO depots?

 

[Soren]

By now its been solidly proven that the British test pilot did not push past slat deployment. He simply wasn't used to them and got concerned when they deployed therefore backing off the maneuver (Hence his comment). This was normal for green 109 pilots as explained by several LW aces. Furthermore this fully explains the results of the British comparative tests and why they are questioned by modern 109 pilots as-well.

The slats also do way more than just lower the stall speed by a few knots, 10 knots wouldn't be unusual.

 

[Crumpp]

I doubt it would do nothing but raise the stall and landing speed by a few knots - there have been many aircraft where because of modifications or problems in the field high lift devices were removed or disabled or limitations placed on flap settings.

It will completely change the stall characteristics and most likely will make the aircraft's stall very dangerous.

Let me know when you find that source. Reason I ask is this will be the very first case I have found of such devices being disabled and the design continuing to operate.

there have been many aircraft where because of modifications or problems in the field high lift devices were removed or disabled or limitations placed on flap settings.

Any docmented examples? These are very much a part of the design. An engineer sets the design parameters to achieve specific design goals. Removing LE devices and TE devices will make certain performance goals unattainable. Things like safe controlled landings or stall characteristics that will not kill the pilot, for example.

As you know, coefficients of lift, drag, and angle of attack are connected in a fixed and finite relationship.

All the best,

Crumpp

 

[FLYBOYJ]

By now its been solidly proven that the British test pilot did not push past slat deployment. He simply wasn't used to them and got concerned when they deployed therefore backing off the maneuver (Hence his comment). This was normal for green 109 pilots as explained by several LW aces. Furthermore this fully explains the results of the British comparative tests and why they are questioned by modern 109 pilots as-well.

No Soren, I think what was shown here is the British had a firm understanding of leading edge slats and how they worked. If this British test pilot backed off a maneuver as alleged in this report, it wasn't out of fear of the system or the aircraft.

The slats also do way more than just lower the stall speed by a few knots, 10 knots wouldn't be unusual.

So you're landing at 76 rather than 65 mph....

 

[DerAdlerIstGelandet]

By now its been solidly proven that the British test pilot did not push past slat deployment.

Soren I am not going to take sides in the arguement. You do however state that this is has been proven solid. Please post solid facts and sources to these facts please.

 

[FLYBOYJ]

Any docmented examples? These are very much a part of the design. An engineer sets the design parameters to achieve specific design goals. Removing LE devices and TE devices will make certain performance goals unattainable. Things like safe controlled landings for example.

As you know, coefficients of lift, drag, and angle of attack are connected in a fixed and finite relationship.

All the best,

Crumpp

Off the top of my head in some Cessna 172s, 182s, the max flap extension was raised from 40 degrees to 30 degrees because of the possibility of "washing out the elevators in a slip." I also know that on the C-17 you could place the aircraft in an "Abnormal Configuration" with regards to LE slat and flap settings.

I've also seen 707s and DC-8s with limited or disabled slat/ slot/ flap systems flown during maintenance ferry flights.....

 

[FLYBOYJ]

Found it - way off topic but this References the -1 TO where a C-17 can be flown outside the normal Flap/ slat configurations...

Abnormal Configuration


(Ref: TO 1C-17A-1 and TO 1C-17A-1-1)



A. C-17A-1-1 Restrictions: (TO 1C-17A-1-1, Paragraph 9-131)

*Actual slat positions are determined used for performance planning

1. CAUTION: With slats retracted, do not use flap settings greater than 20º. Higher flap settings may result in a nose-down approach attitude which could result in nose gear failure at touchdown

a. The flap settings in the C-17 provide the most efficient flap setting for gross weight, CG and ambient conditions which reduce the approach speed in order to give added short field landing capabilities

b. Certain combinations are limited to 5.5º nose-high for forward visibility (unconfirmed source)

2. Some of the approach speeds for abnormal flap/slat configurations appear much higher in order to keep the pitch angle below the 5.5º nose-high limit (unconfirmed source)

3. 20º of flap extension is the maximum if the slats are retracted in order to keep the nose high enough so as not to hit the nose wheel first. Additional flap extension would permit lower approach speeds but would also lower the nose excessively at touchdown (unconfirmed source)



B. CAUTION: With abnormal configuration procedures, use of the AFCS (F/D, AP and ATS) is not recommended because alpha speeds will be incorrect and may not provide adequate margin from stall under abnormal flap/slat conditions. (TO 1C-17A-1, 3-184)



C. Each Spoiler Control/Electric Flap Control (SC/EFC) has an Analog Backup Unit (ABU) that will provide for flap retraction but not extension if the SC/EFC digital function should fail. If a flap asymmetry is evident, the SC/EFC will lock the flaps when a variance of 4.8º develops (3-185)


1. If dual SC/EFC failure has occurred and the flaps are being retracted through the use of the flap ABU, the allowable variance will be 7º before the flaps lock

2. Once the ABU engages in flight because it senses a variance of > 7º, it remains engaged

3. Attempt an EFCS reset (will reset if SC/EFC failure is cause of problem)

If this doesn't clear problem, flaps are locked in place by mechanical jam or hyd problem
If flaps are extended, slats will not retract
Perform ASYMMETRIC FLAPS OR NO FLAP LANDING WITH SLATS checklist



D. Additional Considerations:



If aircraft control is not an immediate concern, the aircraft commander should perform the checklist to calculate the data, review the procedure, and make pertinent decisions on landing gross weight and divert options


If touchdown speed exceeds 182 knots GS, consider further weight reductions


Time, fuel and weather permitting, practice the approach while planning a go-around no lower than 500' AGL so as to observe handling qualities


Fly the approach with a slightly wider downwind and longer final approach than a normal pattern requires


Complete normal landing checklists


Fly using frontside approach characteristics (Pitch = GS, Throttles = Speed)


Normal (3° or less) glide path


Do not flare


Use brakes as required


Use immediate and maximum available reverse thrust


Wx mins 300'/ ¾ SM due to faulty Flight Director