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View Full Version : Combat Flaps: what speed deployed?



Ratsack
03-06-2006, 01:40 AM
There's another thread going about the Spitfire flaps and the ability to map them to a slider or rotary. The usual suspects have raised the issue of the combat flaps of the Bf109, so rather than pollute the other thread (which might actually be reaching a consensus position: what is this forum coming to?!!), I've started this thread to discuss the broader issue.

The broad question is the speed at which combat flaps can be deployed in the game. In particular, some have questioned the ability of the Bf109 to deploy 'combat' flaps at high speed.

The following was posted in the other thread by Buzzsaw:


Originally posted by Buzzsaw-:
Salute

Speed limits for flap deployment on 109's:

E Model

http://img76.imageshack.us/img76/1179/e4flaps1yf.jpg

G-3

http://img76.imageshack.us/img76/8553/g3flaps3de.jpg

From Finnish G2 manual

http://img76.imageshack.us/img76/3262/g2flaps8fc.jpg

From Finnish G6 manual

http://img437.imageshack.us/img437/4771/g6flaps3uv.jpg

Same applies to many other aircraft both blue and red.

In a subsequent post Buzz said these documents represented 'restrictions on deployment speeds for 109 flaps'. I don't think that's quite right, and I'd appreciate the views of the German speakers here.

If I read these documents correctly, they are not restrictions on deployment speeds, but are actually speed restrictions on the plane in particular configurations. That's not quite the same thing as a restriction on deployment speed.

These docs say that if you have the flaps fully down, you mustn't exceed 250 kph. That's fine, and I don't know what speed you have to reach to damage the flaps in FB if you have them fully lowered. Somebody might do a test and post the track, but in any case that's not actually the point.

The point under discussion is the speed at which flaps can be lowered for the purposes of maneuvering. These documents don't tell us anything about that at all. Can anybody provide some information or documentation on this?


cheers,
Ratsack

Ratsack
03-06-2006, 01:40 AM
There's another thread going about the Spitfire flaps and the ability to map them to a slider or rotary. The usual suspects have raised the issue of the combat flaps of the Bf109, so rather than pollute the other thread (which might actually be reaching a consensus position: what is this forum coming to?!!), I've started this thread to discuss the broader issue.

The broad question is the speed at which combat flaps can be deployed in the game. In particular, some have questioned the ability of the Bf109 to deploy 'combat' flaps at high speed.

The following was posted in the other thread by Buzzsaw:

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Buzzsaw-:
Salute

Speed limits for flap deployment on 109's:

E Model

http://img76.imageshack.us/img76/1179/e4flaps1yf.jpg

G-3

http://img76.imageshack.us/img76/8553/g3flaps3de.jpg

From Finnish G2 manual

http://img76.imageshack.us/img76/3262/g2flaps8fc.jpg

From Finnish G6 manual

http://img437.imageshack.us/img437/4771/g6flaps3uv.jpg

Same applies to many other aircraft both blue and red. </div></BLOCKQUOTE>

In a subsequent post Buzz said these documents represented 'restrictions on deployment speeds for 109 flaps'. I don't think that's quite right, and I'd appreciate the views of the German speakers here.

If I read these documents correctly, they are not restrictions on deployment speeds, but are actually speed restrictions on the plane in particular configurations. That's not quite the same thing as a restriction on deployment speed.

These docs say that if you have the flaps fully down, you mustn't exceed 250 kph. That's fine, and I don't know what speed you have to reach to damage the flaps in FB if you have them fully lowered. Somebody might do a test and post the track, but in any case that's not actually the point.

The point under discussion is the speed at which flaps can be lowered for the purposes of maneuvering. These documents don't tell us anything about that at all. Can anybody provide some information or documentation on this?


cheers,
Ratsack

Codex1971
03-06-2006, 05:48 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Ratsack:
If I read these documents correctly, they are not restrictions on deployment speeds, but are actually speed restrictions on the plane in particular configurations. That's not quite the same thing as a restriction on deployment speed.
</div></BLOCKQUOTE>

This is what I suspect to. I would say these speeds represent safe operating limits, not the speeds when structual failure occurs. Engineers often document limits which are far more conservative that actual structural lmiits, i.e. 250km/h is the stated limit for full flaps but they might have a structural limit of say 300km/h.

IIJG69_Kartofe
03-06-2006, 07:19 AM
IMO for ALL the planes i've tested (almost every planes of the game)you can deploy flaps W/O damage them @ 399 km/h, idem for the landing gear.

Abbuzze
03-06-2006, 11:36 AM
It seems all planes can deploy the flaps to combat position at any speed.

Of course use of flaps was limited to a certain speed. But you could also use it at higher speed:


<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">
Me 109 G-6:
"The story of Valte Estama's 109 G-6 getting shot down by a Yak-6 was also an interesting one. Their flight of nine planes was doing high-altitude CAP at 7,000 meters (23,000').
(snip) So it happened that the devil fired at him. One cannon round hit his engine, spilling out oil that caught fire. Estama noticed that it wasn't fuel that leaked or burned, just oil.
He pushed the nose of the plane and throttled up. His feet felt hot, but the fire was extinguished and there was no more smoke. The speedometer went over the top as the speed exceeded 950 km/h. The wings began to shake and Estama feared the fighter would come apart. He pulled the throttle back, but the stick was stiff and couldn't pull the plane out of the dive. Letting the flaps out little by little gradually lifted the nose. The plane leveled at 1,000 meters (3,300').
Clarification of the escape dive: "It didn't stay (vertical) otherwise, it had to be kept with the stabilizer. I trimmed it so the plane was certainly nose down. Once I felt it didn't burn anymore and there was no black smoke in the mirror, then I began to straighten it up, and it wouldn't obey. The stick was so stiff it was useless. So a nudge at a time, (then straightening off with trims).
Then the wings came alive with the flutter effect, I was afraid it's coming apart and shut the throttle. Only then I began to level out. To a thousand meters. It was a long time - and the hard pull blacked me out."
- Edvald Estama, Finnish fighter pilot. Source: Recollections by Eino and Edvald Estama by Finnish Virtual Pilots Association.
</div></BLOCKQUOTE>

Ugly_Kid
03-06-2006, 11:49 AM
Yeah well one can only ask what is the particular use of flaps in the higher speed? Usually you use them at low speed to pull more gee without stalling and that's it.

Surely in game there is an additional effect from the additional nose-up pitch whereas nose-down pitch would be probably more real. This way, for example, P-38J gets additional "dive recovery flaps" at high speed, which get suprisingly unhistorically handy. Apart from this the combat flap deployment isn't much of a use.

Waldo.Pepper
03-06-2006, 01:20 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">whereas nose-down pitch would be probably more real. </div></BLOCKQUOTE>
Such a blanket statement is wrong. It depends on the plane. Some will pitch up and and some down.

Ugly_Kid
03-06-2006, 01:44 PM
The game is the blanket statement here. In the game all planes invariably pitch up with flap deployment.

The more common is nose down for the reason that flaps increase profile curvature and the moment coeffient is affected negatively.

It is not a blanket statement this is a fact.

I quote my papers from profile theory:
"The resulting nose down moment from opening the flaps (in a conventional aircraft) needs to be compensated with a downforce in the tail. The wing has to then compensate this along with the weight. This way part of the gain in lift is lost (typically dCL ~0.1...0.3)"

The only situation where I can imagine flaps causing nose up is when the horizontal stabilizer is affected by the wake of the wing so that the negative angle of attack increases on the stabilizer and the downforce is automatically increased.

Nose down is far more common but you can gladly provide an opposite example.

Ratsack
03-06-2006, 03:08 PM
Guys, the question is not the speed at which you can deploy 'combat' flaps in the game: I can test this myself as well as the next simmer. http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif

What I am seeking is information on the maximum speed at which it was possible to start lowering maneuvering flaps in the Bf109.

The documents Buzzsaw posted don't address this. They only give the speed that shouldn't be exceeded with the flaps fully down, and then provide the suggestion for takeoff that the flaps can be raised once speed reaches 200 km/h.

Abuzze's post suggests Estama lowered flaps at a much higher speed. Unfortunately, that story raises more questions than it answers. Is there another reference for something similar?

cheers,

p1ngu666
03-06-2006, 04:23 PM
i dont think you will find the answer to your question http://forums.ubi.com/images/smilies/16x16_smiley-sad.gif

Grey_Mouser67
03-06-2006, 06:40 PM
I would like to see flaps jamming in combat flap position or not deploy at all modelled in this sim.

I think that the flap thing in general is a big can of worms and, for the most part with notable exceptions, aircraft from bombers to fighters have similar modelling....they weren't always similar and if that were modelled, it would add further complexity to the FM and we would likely enjoy that complexity as long as it was accurate from a relative standpoint and reasonably accurate.

Being a Lightning fan though, I'd hate to see the J model in its current form without combat flaps http://forums.ubi.com/images/smilies/16x16_smiley-indifferent.gif

I would imagine, although I don't have exact figures, the numbers given to pilots have a safety margin in them...so it is likely the speed posted could be exceeded, but I don't know how much and I don't know what the effect would be...damage I suppose but I don't know how.

It would also be neat if different aircraft had the time to deploy and the relative lift for speed penalty modelled as well! Not all flaps were equal and some were easy to deploy and some were not quite as easy or effective!

I think in real life, pilots did not use combat flaps too often...they preferred to save their energy and not let the fight get that slow.

Ratsack
03-07-2006, 09:46 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by p1ngu666:
i dont think you will find the answer to your question http://forums.ubi.com/images/smilies/16x16_smiley-sad.gif </div></BLOCKQUOTE>

Well, thanks for that contribution.

cheers,
Ratsack

Ratsack
03-07-2006, 10:01 PM
I'm inclinded to agree, Grey Mouser. In fact I recall reading that there is no point deploying flaps above corner speed (assuming you can), because it won't gain you an advantage you can use.

Nevertheless, I'm interested to know if there was a 'not above this speed' limit for flap deployment on these planes, and if so, what it was.

cheers,
Ratsack

Capt.LoneRanger
03-08-2006, 01:45 AM
Nice find, but non-relevant for combat-flaps. The figures show what speeds for different flight-maneuvers are allowed:

I'll try to translate for you:

1st pic
Speedlimit:
Deploying FULL FLAPS 250kph
FULL FLAPS deployed 250kph
with extended landing gear 350kph
lowering/raising gear 220kph
dive limit 750kph

2nd pic
(text about what official laws and rules the statements apply to)

SpeedLimits:
Flight with fully deployed flaps 250kph
Flight with lowered landing gear 350kph
dive-limit 750kph



These figures are all for full (landing) flaps. Has nothing to do with what is called "combat flaps" in IL2. http://forums.ubi.com/images/smilies/10.gif

faustnik
03-08-2006, 01:54 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Grey_Mouser67:


Being a Lightning fan though, I'd hate to see the J model in its current form without combat flaps http://forums.ubi.com/images/smilies/16x16_smiley-indifferent.gif

I would imagine, although I don't have exact figures, the numbers given to pilots have a safety margin in them...so it is likely the speed posted could be exceeded, but I don't know how much and I don't know what the effect would be...damage I suppose but I don't know how.

It would also be neat if different aircraft had the time to deploy and the relative lift for speed penalty modelled as well! Not all flaps were equal and some were easy to deploy and some were not quite as easy or effective!

I think in real life, pilots did not use combat flaps too often...they preferred to save their energy and not let the fight get that slow. </div></BLOCKQUOTE>

But, P-38s from the mid-F production run and later had specific "combat" flaps designed to be used in turning fights. So, even if other a/c are restricted the P-38 should not be.

Ratsack
03-08-2006, 03:47 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Capt.LoneRanger:
Nice find, but non-relevant for combat-flaps. The figures show what speeds for different flight-maneuvers are allowed:

I'll try to translate for you:

1st pic
Speedlimit:
Deploying FULL FLAPS 250kph
FULL FLAPS deployed 250kph
with extended landing gear 350kph
lowering/raising gear 220kph
dive limit 750kph

2nd pic
(text about what official laws and rules the statements apply to)

SpeedLimits:
Flight with fully deployed flaps 250kph
Flight with lowered landing gear 350kph
dive-limit 750kph



These figures are all for full (landing) flaps. Has nothing to do with what is called "combat flaps" in IL2. http://forums.ubi.com/images/smilies/10.gif </div></BLOCKQUOTE>

Yep, that's pretty much what I gleaned from it, but I don't trust the vestigial remnants of my high school German. Nice to see somebody else come to the same conclusion.

cheers,
Ratsack