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

[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]

Originally Posted by Crumpp

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]

[QUOTE=davparlr;289640]

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]

Originally Posted by 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.

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.

Originally Posted by Soren

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]

Originally Posted by Soren

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]

Originally Posted by Crumpp

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

[Crumpp]

Abnormal Configuration

If this doesn’t clear problem,

If aircraft control is not an immediate concern

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

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

Use immediate and maximum available reverse thrust

Certainly the USAF includes emergency procedures in the event of a mechanical failure.

That is not the same thing as a design purposely having the slats fixed and then continuing to be operated.

All the best,

Crumpp

[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."

TE flaps are being reduced. Not the same thing as LE slats being disabled for normal operation. Lets clear up the confusion here. I did not catch you refered to TE devices. Different characteristics and I would have specified so had I caught this.

There are many designs that do not have any flaps at all that operate safely. The point is however, that a design with LE devices cannot have the LE devices safely disabled and continue normal operations. The LE devices are there to achieve a design performance goal.

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

Certainly, they were being flown to a location in order to be fixed. Again not the same thing as being disabled for normal operation.

All the best,

Crumpp

[FLYBOYJ]

But the bottom line the aircraft shown can be flown and were flown under certain conditions and it would not be unreasonable to believe that in a combat situation and in a foward combat area an aircraft like the Lysander would operate with its LE slats closed due to maintenance limitations...

BTW I'm still searching for the article about the Lysander's LE slats being disabled....

[Kurfürst]

Originally Posted by davparlr

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.o...5342-level.jpg

Please see below.

Originally Posted by davparlr

The P-51D was introduced into the 8th AF in March ’44. The Bf-109K was introduced in November, ’44.

I am afraid this is incorrect, I trust Bill on this, and practically all publications I`ve seen say June 1944 for the P-51D as an introduction date.

The 109K was introduced in during October, units received it in huge numbers already that month (some 200 were around, even though some were wrecked during refit). It was certainly in combat by the start of November since the first combat loss is known from 2 November 1944.

So, if you want to keep the playing field truely even, you need to find the first date by which at least 200 P-51Ds were in service with first line units, and, they suffered losses in combat. For the 109K, it`s November 2, even though it was in production since August 1944.

To me a couple of months seems rather indifferent, and, there were plenty of 'interim' aircraft produced since early 1944 which ensured the 109K`s absance until October 1944 was not really felt - the K itself offered mostly just cleaner lines and more importantly, a standardized airframe with rationalized internal arrangements.

Originally Posted by davparlr

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.

I think the 51F wasn`t introduced at all, or the p51H for that matter in the second half of 1944. I`d suggest you check out the new models of 109G that were introduced in the first half of 1944, especially the /AS types with methanol. By all accounts, these were excellent aircraft, and very close to the 109K in performance, albeit some 20 km/h slower due to their less clean airframes. Nevertheless, they stepped in for the 109K and DB605D since March 1944 as an interim solution.

Originally Posted by davparlr

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.

There`s much speculation in this and grossly underestimates development problems. Germany, who was desperate to stop the hordes of P-51s, P-47s, B-17s, B-24s, and Brit planes, with advanced aircraft, as you say, was developing the 109K since March 1943. How much easy it would have been for them to have it, one may say, by late 1943...? It`s certainly very easy to say - but in It took them until late 1944 until it actually arrive at the units, and it was far less radical departure from the existing G-airframes. Not to mention, that to my best knowledge, the F-series Mustang, as hot their spec are, are essentially experiemental aircraft that toyed with the idea of lowering airframe stress limits and weight in favour for higher performance. Apart from it never been realized in this form, it`s also questionable how much use such lightly stressed aircraft would be operationally, how many potential problems would be needed to be solved with the airframe and engine before it would be combat ready, how long it would take factories to re-tool etc.

I don`t like such speculations, and after all, the facts are on the table, we know how it was, anything else is a swamp of guesswork, riddled with dangerous intellectual traps every step. The 51F did not become an operational type just and the P-51H, which just missed the war, eventually did not produce the very impressive performance figures originally expected and calculated for it.

Originally Posted by davparlr

My multiple sources show that the P-51D was capable of 375 mph at SL at about 1640 hp.

Individual aircraft performance of course, differ from plane to plane, and it especially seems to be true w the Mustang.

I prefer this one for the P-51D Performance since it notes that 'the data presented represent good agreement with most of the flight test results'. It`s probably a good middle-value.

It shows 368 mph at SL, and I presume the wingracks are missing (I could be wrong), which chopped some 12 mph off from top speed and were std fitting. With them it would do about 356 mph, and there`s also a test with the RAF`s TK 589 which I have which had 354mph at SL (w. racks).

The one you shown, with 375 mph claimed at SL at the same rating of 67", from June 1945, is very much higher than that. I can only guess why - perhaps an exceptionally good aircraft was tested, and/or it was polished and had special surface treatment. But I doubt it`s normal (and so do even North American, see above), it`s probably the best figure around.

The Bf-109K had 1800 horses available and could not achieve that (and my source for that is not Mike Williams site).

The 109K had 1800 PS in it`s earliest engine that was not fitted to too many aircraft though, or 1850 or 2000 PS. With the two latter ratings, it was officially rated at 370mph and 377 mph respectively, and some 8 mph if polishing was applied.

And of course, as in the case of the Mustang, there were worser and better planes. The tolerance was usually 3%, so theoretically you could have a production 109K anywhere between 360 mph (a plane w. the lowest rating, so badly built it just passed acceptance tests) and ~395 mph (a plane with the highest rating, with exceptionally good finish, polished by the loving groundcrew).

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.

That`s what puzzles me. I have seen half a dozen set of data for the the F4U4, and none of them agree. It seems they were continously revised, for some reason.

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.

You may find this kind of climb rate data (copies of the original papers) on my site, for both 1,8 and 1,98ata. Mike used to have 1,98ata performance displayed, ableit barely visibly on some previous version of his controversial comparison articles, but appearantly he couldn`t bear it even being there so he removed it a while ago. It seems some of his current values for the K-4 at 1.8ata are in fact taken from the K-6 heavy fighter.

In any case you can view the whole thing on my site, here : Kurfürst - Performance of 8 - 109 K4 and K6 with DB 605 ASCM/DCM This is the only thing, I dare say, most if not all of us aircraft geeks have on 109K performance.

[Crumpp]

But the bottom line the aircraft shown can be flown and were flown under certain conditions and it would not be unreasonable to believe that in a combat situation and in a foward combat area an aircraft like the Lysander would operate with its LE slats closed due to maintenance limitations...

For a single incident on a one time maintenance flight to be repaired. Maybe...

As for continuing normal operations, no way.

Nothing you have shown has any aircraft continuing to operate normally.

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

Do you know for a fact the LE slats were disabled on these?

You are pilot correct? Have you made many frontside curve approaches?


All the best,

Crumpp