Flaps usage in real combat

[icepac]

Why would you use flaps at 300 IAS? No G limits?

You mention other sources with flap speed data but you don't list them.

Kilometers per hour.

[Brooke]

1; nope never said that, or at least never meant to communicate that.  What I said is that the low deflection FDS are too low on most FMs in AH

Sorry, meant to say that "You feel that max flap-deployment speed for aircraft in AH is too low" (mistyped "high" instead of "low" in my previous post -- but I mean low). "You feel that max flap-deployment speed for aircraft in AH is too low" means the same thing as "the low deflection FDS are too low on most FMs in AH".

, And that if the low deflection FDS are not specifically stated in the POH, HTC's apparent preferred source, that the unlisted speeds could be easily calculated using the calculated force loads calculated from the "known" or in this case POH stated deflection/s safe FDS.

As I've said before, since low-deflection flap deployment happens at a higher speed than higher-deflection flap deployment, that is proof that HTC takes it into account already.

2; since the accepted data is limited to one type of source in this case, no I can not produce safe deployment speed statements for deflection angles that the publishers of the documents did not include.  Otoh neither can HTC, yet he does so anyway, just at substantially lower speeds than a lot of other sources of data and or information would put them.

It's not limited to that, and you have no idea what HTC has as data.  Do you think that a manual says "full flap deployment shouldn't be done above X speed" so they make X the limit of deploying 10 degrees of flaps?  If you think that, you are mistaken, because the planes in AH deploy 10 degrees at a higher speed than full flaps.

3; the absence of reports of a problem, is strong evidence that there was no problem.  Especially when fighter pilots are involved.

Yep, not much of a problem.  Probably because no one was trying to deploy flaps at 250 mph in their FW 190's.

The absence of reports of people deploying flaps at high speeds is strong evidence that people didn't much do that; hence, no problems.

4; my point is that since the wind forces are the same, and the flap is the same, then the relationship between the flaps and the wind forces should be the same. 

Let me try another approach.  One barn door in the wind has a 8 year old holding it open and another barn door of exactly the same configuration in the same wind has a strong 21 year old holding it open.  Force on the barn door is the same, yes, but which one will be held open in the strongest wind?  Obviously the one with the 21 year old.  Now, replace 8 year old and 21 year old and barn doors with actuator mechanisms and flaps.  You get the idea.

5; no, flaps are different size, type, have different max deflection angles, and or a deflection angle settings, all will result in different FDS for different aircraft.  However (and this is what you are not getting) the relationship  between deflection angle and airspeed and force should be the same.  . . .

See above comment.

Last time I played il2 FDS was @ 300ias for most planes with low deflection flap settings, ask anyone who knows about 10 degrees of flaps vs 60 degrees and safe deployment speeds and se what they say.

The last time I flew planes in Battlefield 1942, it gave me the idea that a P-51 should carry 50 bombs and have a turning radius of 100 ft.

Funny all I see here is you and all you do is ask for "data" and when I provide some all you do is go to extreme amounts of supposition to attempt to refute it.

You haven't provided any data at all on flap deployment speeds.  Thoughts and discussions are not data.

  Where is your army of experts that say flaps get weaker at lower deflection angles?

Flaps getting weaker at lower deflections?  That's the opposite of what I've been saying.  That the force on flaps is lower at lower deflections is about one of the only things I agree with you on.

[bustr]

With all of the EU companies now rebuilding 109 and 190, why haven't any of you gone through the laborious process of contacting those companies and asking them about flap actuation?

So far there is no one in this argument presenting a reason for Hitech to change his choice of modeling. Only a reverse logic of: if you cannot prove me wrong, and my argument is only a comparative observation presenting no specifics for you to refute on the data for each aircraft in question, then Hitech is and idiot and I win. Internet era anonymous identity debate skills.

Brooke,

Didn't someone start this same argument about 7 years ago in our forum as his reason for never playing AH again? Because Hitech refused to make the 109 and 190 flaps actuate at the same speeds IL2 did?

Brook and Brent,
Contact this company who restores Bf 109 and ask them about flaps. I have to go through laborious crap like this to research gunsights from around the world. Otherwise, this whole conversation has been about calling Hitech an idiot in his own forum while getting away with it.

Hartmair Leichtbau GmbH

 Michaelsweg 9
 D-85356 Freising (Ortsteil Tüntenhausen)

 Tel. 0 81 67 - 69 37 43

mail@leichtbau-gmbh.de

[FLS]

Kilometers per hour.

Thanks, that makes a little more sense but if it includes US aircraft then they got neutered.

[FLS]

Really? Why is that? What device stops them?  What is the structural difference between a split flap and a p38 speed flap?  FYI the plane we were discussing did not have trim tabs so you should either be more clear or re read the thread.

The same reasons  p51 pilots used their flaps at high speeds. 
Point being they were similar structures designed and used for the same things. 
What is the difference between a p51 flap and a 109 flap? Do you know?
No I said others came to different conclusions. when the data was not conveniently specific enough.

I Was discussing il2 s different conclusions from the same data pool as HTC, not relative aerodynamic credibility.  BTW the same could be said of using HTC as an aerodynamic reference.  

The P-38 dive flap is not a high lift device. You can't compare it to regular flaps.

The 109 slats are essentially all speed "combat flaps". The P-51 has the speed limited combat flap setting of 10 degrees.

[Brooke]

BUTTFACES!

http://m.youtube.com/watch?v=LUIiX8TDF2c

[Brent Haliday]

The absence of reports of a problem could also mean that the flaps on some aircraft were not used the same way that they were used on others or people don`t feel the need to search for such information. Pilots in WW2 probably didn`t calculate forces and deployment speeds for flaps at lower settings based on some information found in POH. So maybe overspeed damage is missing because they were not used in such a way.

Or you could read the pilot account below and realize that low deflections result in low levels of stress on a flap structure, no matter who manufactures the aircraft in question.

Compressibility effects vary greatly between different aircraft. In the 109 both trim and flaps were used to pull out of dives.

"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.

[Brent Haliday]

...

Let me try another approach.  One barn door in the wind has a 8 year old holding it open and another barn door of exactly the same configuration in the same wind has a strong 21 year old holding it open.  Force on the barn door is the same, yes, but which one will be held open in the strongest wind?  Obviously the one with the 21 year old.  Now, replace 8 year old and 21 year old and barn doors with actuator mechanisms and flaps.  You get the idea.

...

Flaps getting weaker at lower deflections?  That's the opposite of what I've been saying.  That the force on flaps is lower at lower deflections is about one of the only things I agree with you on.

Just going to address the above two comments as this is where you are missing my point.
I agree with you analogy however that has nothing to do with what I am saying.

So now imagine the 21 year old and the 8 year old have different size doors so that each of them can open their respective door to 45 degrees into the wind at 50 miles an hour.  Since the same wind speed results in the same ability to open the door at 45 degrees that means that whatever the wind speed happens to be, their ability to open their respective doors should result in the same angles of deflection because the wind speed is the same at the same side of the barn and no matter what angle the door is at or how fast the wind is blowing the boys are the same Strength, not compared to each other, but compared to themselves when the wind was 50 mph and the door was at 45 degrees. That is what I am saying, and that is not anything like the way HTC represents things in the game.

[kvuo75]

I think diving bf109's up to 950km/h is solid flying.

[bozon]

Just going to address the above two comments as this is where you are missing my point.
I agree with you analogy however that has nothing to do with what I am saying.

So now imagine the 21 year old and the 8 year old have different size doors so that each of them can open their respective door to 45 degrees into the wind at 50 miles an hour.  Since the same wind speed results in the same ability to open the door at 45 degrees that means that whatever the wind speed happens to be, their ability to open their respective doors should result in the same angles of deflection because the wind speed is the same at the same side of the barn and no matter what angle the door is at or how fast the wind is blowing the boys are the same Strength, not compared to each other, but compared to themselves when the wind was 50 mph and the door was at 45 degrees. That is what I am saying, and that is not anything like the way HTC represents things in the game.

Why would you assume that all manufacturers normalized the flap structural strength to the same airspeed? It makes no sense.

In some planes flaps were clearly not intended to use for anything other than landing. This is abundantly clear in the low wingloaded planes that employ the most simple and primitive flaps. They needed the extra drag much more than high AoA lift - their landing speed was already quite low. High wing loaded planes absolutely needed effective flaps (i.e., lift not just drag) in order to lower their otherwise very high landing speed. That meant deploying them at a higher speed to begin with, which in turn required them to be stronger.

A rule of thumb in engineering is not to over-spec. If the flaps do not need to be stronger, they are not made stronger because this means weight, cost and complexity. For this reason very few planes used Fowler flaps. They are effective, but also heavier, complex (less reliable, more maintenance) and increase the costs. In something as big and heavy as the P-38 that seemed like a reasonable thing to install. Not so much in a spit. In the P-38, which was already heavy, adding a little extra strengthening to the flaps at the cost of more weight made little difference to the total weight, but would allow the flaps to be deployed at combat speeds. Lockheed probably recognized a weakness in the 38's turn ability due to the high wing loading and decided to offer a partial solution through complex flaps instead of making the wings bigger. In that specific case, designing the flaps for use at 200+ mph may have made sense. Why would a Spit or a Zero need to deploy flaps at speeds in which they can pull into a blackout?

Bottom line, different flaps on different planes were not designed for deployment at the same speeds, or withstand the same forces. A spit flaps will likely suffer damage at a lower speed than a P-38's flaps. Kurt Tank obviously did not think his 190s need to turn better. Giving up low speed turning is what made these planes so effective.

[FLOOB]

http://m.youtube.com/watch?v=LUIiX8TDF2c

[Brent Haliday]

Why would you assume that all manufacturers normalized the flap structural strength to the same airspeed? It makes no sense.

In some planes flaps were clearly not intended to use for anything other than landing. This is abundantly clear in the low wingloaded planes that employ the most simple and primitive flaps. They needed the extra drag much more than high AoA lift - their landing speed was already quite low. High wing loaded planes absolutely needed effective flaps (i.e., lift not just drag) in order to lower their otherwise very high landing speed. That meant deploying them at a higher speed to begin with, which in turn required them to be stronger.

A rule of thumb in engineering is not to over-spec. If the flaps do not need to be stronger, they are not made stronger because this means weight, cost and complexity. For this reason very few planes used Fowler flaps. They are effective, but also heavier, complex (less reliable, more maintenance) and increase the costs. In something as big and heavy as the P-38 that seemed like a reasonable thing to install. Not so much in a spit. In the P-38, which was already heavy, adding a little extra strengthening to the flaps at the cost of more weight made little difference to the total weight, but would allow the flaps to be deployed at combat speeds. Lockheed probably recognized a weakness in the 38's turn ability due to the high wing loading and decided to offer a partial solution through complex flaps instead of making the wings bigger. In that specific case, designing the flaps for use at 200+ mph may have made sense. Why would a Spit or a Zero need to deploy flaps at speeds in which they can pull into a blackout?

Bottom line, different flaps on different planes were not designed for deployment at the same speeds, or withstand the same forces. A spit flaps will likely suffer damage at a lower speed than a P-38's flaps. Kurt Tank obviously did not think his 190s need to turn better. Giving up low speed turning is what made these planes so effective.

No#1 the use of Factor of safety procedures is universal so aircraft are always designed to be stronger than they need to be. Especially combat aircraft and more stringent are fighter aircraft Factors of safety.  They are designed so as to never fail under foreseen stress loads, as much as possible.

No#2 since after much discussion we have all come to agree that it is the force load that is the limiting factor in FDS,
And that less deflection means more speed then my barn door explanation begs the question as to why some aircraft
That have fully extended flap speeds that are so very similar have low deflection flap speeds that are so far apart.  physics and aerodynamics can not account for the difference, only the data selection process explains that.  And data selection 60 years after the fact has little to do with real world capabilities in WW2.

No#3 since we know that there was at least one button on the FW-190 flap deployment control called maneuver, you are again mistaken about Mr. Tank's design intentions.

[bozon]

Button label is great, but maneuvering at what speed? The discussion is pointless unless somebody comes up with official numbers. HTC will not change anything otherwise.

[Brooke]

In modeling, you only make assumptions if you have to.

1.  If you have data that says "don't deploy 10 degrees of flaps above X mph", then you use that.

2.  If you only have data that says "don't deploy full flaps above X mph", then you make some assumptions based on force to decide when 10 degrees of flaps can be deployed.

HTC clearly does either 1 or 2 for each aircraft, since 10 degrees of flaps in AH aircraft can be deployed at a higher speed than can full flaps.

What you are arguing, Brent, is that:
-- In the cases where HTC is doing 1 above, it is a bad choice because the stated data is too conservative, and that they should always do 2; and
-- In the cases where HTC is doing 2 above , they are misestimating when 10 degrees of flaps should be deployed.

I feel that 1 is preferable to 2 when you have the data; and in the cases where HTC is doing 2, I trust their estimations still.  Also, it doesn't even matter except for maybe a couple of aircraft that I know of in the game (the 190 and the A-20).

As for the barn-door example, what is your pick of two planes that have the same full-flap deflection speed but significantly different 10-degree flap deflection speeds?

[Brent Haliday]

I have stated before that specific data is easier, and that I would not presume to redesign the perameters that HTC uses to define the FMs, at least not for free.

However in the case where data is "known" for one plane that data source could be used as a guide for other planes with similar capabilities yet lacking the easy data.  You could estimate conservatively and still be reasonable, that would solve the problems especially with really problem FMs like the a20 190 etc.

I think however you look at the deployment speeds in the game you will find that the FDS speeds/deflections are much more pronounced at low angle setting then they are as you approach max deployment for all the aircraft allowed the higher low deflection angle speeds when compared to those not granted that ability because of the data selection choices.  Try the 109 e vs the p51d same type of flight flaps and max deflections are pretty close and the size difference fits nicely with my barn door example.  Computer modeling allows you to do whatever you want no limits are put on the designer, IMO the proof of success in a sim of this type is how well it plays vs. real world combat accounts, as these types of games are not really flight simulators as much as they are air combat simulators.  Otherwise the education burden would be impractical for an entertainment source.  As an entertainment source they do pretty well IMO.