109s and Flaps

[FLS]

Yeah, you can know pudding is vanilla if you eat it, and know that it isn't chocolate.

But you're trying to say that slats are just as effective as flaps at 10 degrees deflection when at high speeds, which is akin to trying to tell what ingredients are in the pudding.



Once again, burden of proof rests with the accuser. I'm interested to see what your source of information is.

You can learn a lot about the Aces High aircraft by flying them.

To continue with the pudding, yes, I gave you the ingredients. They don't appear to be helpful without the recipe. 

Was there something in my explanation that wasn't clear? Nothing I posted is as controversial as you seem to believe.

[Tank-Ace]

You've said the slats are about as effective as 10 degree flaps at high speed, but have offered no evidence for your statment.

Slats only increase the wing area, while flaps either increase the camber of the wings or the area AND the camber of the wings.


slats are also relativly small, so the total increase in wing area is likely negligable.

[gyrene81]

i'm sorry fls, but there is no way the slats on the 109 are popping out at 400mph unless you effectively stall it out where there is zero forward movement on the leading edge of the wings...and then they are not doing anything for the aircraft. i've run the 109 in stall fights and the slats do nothing to decrease the turning radius compared to 1 notch of flap deployment.

[FLS]

You've said the slats are about as effective as 10 degree flaps at high speed, but have offered no evidence for your statment.

Slats only increase the wing area, while flaps either increase the camber of the wings or the area AND the camber of the wings.


slats are also relativly small, so the total increase in wing area is likely negligable.

No I never said that. I said essentially the opposite of that.

I don't know the actual difference in coefficient of lift between 10 degrees of flaps and slats.  If you have some data on that it would be interesting to see it.

Slats and combat flaps both increase the Cl without adding a lot of drag. Which part of that do you disagree with?

[FLS]

i'm sorry fls, but there is no way the slats on the 109 are popping out at 400mph unless you effectively stall it out where there is zero forward movement on the leading edge of the wings...and then they are not doing anything for the aircraft. i've run the 109 in stall fights and the slats do nothing to decrease the turning radius compared to 1 notch of flap deployment.

It's all about AOA. You stall at a particular AOA, the slats pop out at a particular AOA. I didn't say it was a good idea to have that much lift at 400mph, you're over 6 Gs. The point is that they do operate and they do increase the Cl at those speeds

[Krusty]

Tank Ace, you don't understand the basic principle of the slots on the Bf109s. They do NOT increase wing area. They allow airflow to duct over the top of the wing preventing loss of control in a stall. Thus you retain aileron control through the stall (at least, further into it).


I haven't read this entire thread, as it bloomed into 4 pages rather fast. IMO if you're using flaps in a 109 you need to be doing one of the following:

preventing stalling out at minimum speeds
trying to dead-slow out-turn somebody with max flaps
coming over the top of a hammer head of some sort
LANDING


Emphasis on the last bit.


If you're using flaps for turn advantage when you're not at stall speed, you're doing it WRONG in my opinion. They don't work like combat flaps on F4us or P38s. You can't work them like that and expect a benefit of similar gains.

If you're in a 109 use the vertical, use your horsepower, use your tight turn radius... But flaps are 99% useless for most of my sorties. Keep in mind I've landed too many 8,10,12 kill sorties in Bf109s to count. I'm no expert but I do know a few things about flying them in the MA environment.

[gyrene81]

i believe what tank ace and owlblink are getting at is, why can't the flaps on the 109 be used as combat flaps at higher speeds. there is nothing anywhere showing that 109 pilots didn't/couldn't use some degree of flaps to improve turn performance at high speeds just like the 51, 38 and other u.s. aircraft...not 300+ mph of course but maybe around 225mph or so.

[FLS]

i believe what tank ace and owlblink are getting at is, why can't the flaps on the 109 be used as combat flaps at higher speeds. there is nothing anywhere showing that 109 pilots didn't/couldn't use some degree of flaps to improve turn performance at high speeds just like the 51, 38 and other u.s. aircraft...not 300+ mph of course but maybe around 225mph or so.

It's probably better in general if the flight modeling is based on evidence of use instead of wishful thinking and a lack of evidence of non-use. 


225 is about corner velocity for BF109F4. You don't need flaps if you can pull 6 Gs.

[gyrene81]

It's probably better in general if the flight modeling is based on evidence of use instead of wishful thinking and a lack of evidence of non-use. 

i agree, but it's not...i.e. p-40

[FLS]

i agree, but it's not...i.e. p-40

Are you referring to the bug that they fixed after redoing the flight models?

[gyrene81]

not a bug...but i am talking about the manner in which the determination of the speed was deduced.

[FLS]

not a bug...but i am talking about the manner in which the determination of the speed was deduced.

Are you saying it was determined by a lack of evidence of non-usage? If you tell me specifically what you mean I can stop guessing   
 

[gyrene81]

   ok, without starting any long drawn out arguments (which i'm sure is not entirely possible), this is the deal...

initially the flap deployment speeds were determined by what is stated in the pilots manual...clean configuration no externals


then, baumer posted this




and i agree with his statement...

I'm sorry, you are correct it calls for 1/2 flaps and not to retract below 160mph.

On the second point, my primary concern is that it is an educated guess unless it is specifically stated in a source document. Allowing some modeling for the P-40 based on a guess but holding other aircraft to only documented numbers seems contradictory to HTC's SOP.

the thing is, it's one thing to be prevented from doing something due to an electro-mechanical fail safe or whatever, but nothing except physics would prevent a manual device from working. obviously in a high g maneuver the 109 pilot has his hands full due to the design of the controls system where a p-40 or p-51 pilot wouldn't have such issues and could easily flick a switch.

[FLS]

Link? I missed that thread and I'm missing your point Gyrene. What do you think  was modeled by a lack of evidence of non-usage? HTC doesn't publish which documents they have and use.

[gyrene81]

http://bbs.hitechcreations.com/smf/index.php/topic,322587.0.html
it's all in that discussion, just have to read it carefully.

hitech has specifically stated primary source for their decisions were the pilot's handbooks. my point is, there are no documents specifically stating 8 degrees of flap deflection is prohibited on the 109 at any speed for any reason, the only specification is full 40 degrees of flaps with landing gear down and just landing gear. and of all aircraft that should have flap deployment speeds above landing gear deployment speeds it's those with manual flap deployment systems.