Flap Drag testing

[Dakpilot]

This question was posed in questions for developers recently

 

"Yak-1 flaps are self retracting while they shouldn't be, but anyway, this was done with both flaps fully extended so the question still stands - why do Fw190 flaps fully extended cause twice the drag Yak-1 flaps cause fully extended?" 

 

Disregarding the pneumatic retracting flaps for a moment, How does one do a test to 'isolate' the sole difference between effect of drag on flaps between the two very different aircraft with reference solely on effect of flaps? to get a figure of twice the amount on FW190, genuine question 

 

the two aircraft have very different weights which will have a constant effect on drag, the two aircraft have very different drag coefficients  and power outputs, notwithstanding that "ingame" the Yak has to be flown below a certain airspeed to deploy/maintain full flaps

 

What test would be done that isolates ONLY Flap drag only as a comparison between these very different aircraft to get these results, no who is right or wrong, I am just interested in the test

 

Cheers Dakpilot

[JtD]

I tested flaps up, flaps down, noted the speeds, isolated induced drag using real life handbook figures and had the parasitic drag remaining. It triples with the Yak and increases sixfold with the Fw190. Even accepting large margins of errors in the methods of testing, a difference with factor 2 is way too large. I originally posted my findings here:

 

http://forum.il2sturmovik.com/topic/16784-yak-can-keep/?p=275172

[Dakpilot]

Surely if FW190 flaps are producing twice the amount of drag expected this would lead to some very strange landing approach issues with full flaps? or exploit as a great airbrake

 

If it is the Yak (in your figures) that is wrong then what is up with the La-5? not seen anyone claiming massive energy retention/UFO issues with that A/C during online ACM

 

In a simpler, test when aircraft are flown within full flap operating speeds are any huge or too small speed decreases noticeable when full flaps are deployed?

 

Cheers Dakpilot

[JtD]

I'd guess the La-5 doesn't get the attention the Yak-1 gets because it doesn't have the auto retract feature. But, imho, the La-5 flaps appear to be modelled generously, in particular if you compare it to the very similar system of the LaGG-3.

 

You can see the simple speed figures on the left side of the table in the linked post - retracting flaps increased the Yak-1 speed from 220 to 350, the Fw190 speed from 220 to 445. This figure alone implies a change in total drag for the Fw190 of about 8, for the Yak of about 4.

 

Since I don't really play this game I haven't investigated the landing behaviour of the Fw190 in detail, but yes, it's draggy as hill.

[Dakpilot]

Without power settings to compare excess power/torque available i dont see how flyiing at same speed and raising flaps gives any acurate data, (different weights and power and probably prop setting) as with all tests they need validating with another, maybe glide test and see how much slowdown after dropping full flaps within operating limits, again this can only be a very generalised test due to different aircraft/systems

 

Cheers Dakpilot

[JtD]

Well, this was my test and I'd be happy to see someone else do another test that can deliver equally or more accurate results. Indeed, a dive test would be another possibility, but will have their own problems. Go ahead.

 

I on the other hand don't see what relevance excess power or torque have, if I use 500hp for sustained level flight I don't care if that is 30% or 60% of what my engine can deliver. Weight was accounted for hence all the maths indicated in the table. I could be more accurate if the game gave the exact weight of the aircraft, but playing with the figures I found that plusminus 20% weight have an irrelevant impact on the result. Or maybe I just don't get where you see a problem.

 

All in all my results are by far the most accurate results published on this forum up to now. I won't bet on 3 or 5 or 10%, but 100% is far, far outside of possible error. I'll be happy to adjust my perception when more accurate data becomes available.

[JtD]

Btw, as this was taken from the ask the devs topic, this is the reply:

 

You can't measure the drag in these conditions. It nothing but your emotions.

Guess there's no such thing as flight testing let alone flight simulation, things can't be measured, things can't be calculated. While hilarious, such a clueless response is also quite disappointing.

[Dakpilot]

I think you will find that reply is simply language/translation issue, rather than hilarious clueless response, perhaps if you had linked your tests it may have been considered in a better light

 

It really is not surprising that dev's do not like to interact with people  when constantly called hilarious and clueless and suchlike, sorry if that seems harsh but it is only my point of view

 

They have also said that questions for dev's is not correct place for discussing FM/performance issues...rightly or wrongly

 

Cheers Dakpilot

[JtD]

It doesn't need my tests if even the most simple speed check shows a factor 2 difference as well. If Han had ever bothered to look at what happens when the aircraft lower or raise their flaps, he'd know there's something fishy. Instead, as per usual, in complete ignorance of in game behaviour, he's blaming other peoples feelings for BoS flight model errors. I know I'm harsh as well when I call it clueless and hilarious, but then I'd say I only call it what it is.

 

And yes, ask the devs is not the right place for FM discussions, this subforum would be, but then they don't touch it with a stick. They are probably too afraid of all the emotion.

[Jason_Williams]

Btw, as this was taken from the ask the devs topic, this is the reply:

 

 

Guess there's no such thing as flight testing let alone flight simulation, things can't be measured, things can't be calculated. While hilarious, such a clueless response is also quite disappointing.

 

The team is hardly clueless and your personal insults get this thread closed.

 

Jason