Planning flaps testing test plan

[Voyager]

Basically want to put together a simple and repeatable test of the flaps behavior in the P-47, and am looking for inputs to get solid runs. 

 

The theory that I want to test is that, in level flight, flaps should be expected to increase drag, and reduce stall speed. 

 

To test this, I'm proposing setting a P-47D-28, 100% fuel, with fixed loadout (extra ammo, all equipment including bomb racks, no external stores), using an air start at 1,000m and setting mixture to Auto lean, MP to 35", RPM to 1800, turbo to 0%, Oil Radiators to 100% Cole flaps to 30%, intercooler to 50%, aircraft in auto-level and then recording the equilibrium air speed with flaps up. If that equilibrium sipped is higher than 150mph indicated, reduce MP until an MP that produces a150mph IAS is identified and recorded. Then decrease manifold pressure until a stall is produced, then restart the flight and repeat this procedure for each of the numbered flap markings on the wing. 

 

My postulate is that the air speed for a given flap position will be lower for a given power setting, and that the stall speed will also be lower.

 

Anything missing in the test cycle? General thoughts? 

[Voyager]

Initial results, 150ias was at 56% throttle clean, stall was 120 IAS

 

10° 140mph at 56%, stall of 110

20° 130mph at 56%, stall of 106

30° 115mph at 56%, stall of 106

40° 85mph at 56%, stall of 85

 

The 40° flaps behavior appears to be an outlier, and I'll want to retest it a few times. One thing I did notice is that the angle of attack limits went way up once the flaps got to 30° deployed, as in the plane could sink at a high rate with the nose on the horizon and still have control authority. 

 

Afterwards I did try running the power up to see how it impacted the stall. I'll need to do a more thorough test, but at the 40° setting, running at 60", it seemed to drop the stall speed to the 60-70 mph indicated range. 

 

One thing that did cause some repeatability complications was the discovery that auto-level cuts out at 130mph.

[JG27*PapaFly]

I suggest recording two to three polar diagrams in the power off or engine off condition at a fixed prop pitch.

In order to do this you would glide at a given IAS, starting from e.g. 1500 m ASL, and record the average sink rate for at least  4 speeds covering a range from stall speed to perhaps 400 kph. With tacview you get a lot of data, including the AoA.

 

In the end you plot the curves. The dots on the curves show you the lift-to-drag ratio across the speed range. If the modeling is correct in-game you should see that the L/D  ratio gets worse and the whole plot shifts towards lower speeds with increasing flap settings.

 

Here is the polar of the Fw190 A5 (no flaps).

 

From this you can calculate the L/D ratio, also known as glide ratio. As you see the clean wing 190 peaks at an L/D of close to 12 at 260 kph IAS. The complete L/D plot would shift to the left and to lower glide ratios when deploying flaps.

 

[Voyager]

Could you walk me through what a polar chart is and how it's generated in this context? 

 

Also, are there ways one could generate the L/D for high power settings? 

 

Also, what command am I looking for to directly control the prop pitch? I've managed to get the prop RPM controlled and have found the command to toggle it to manual control, but apparently the control for prop rpm is separate from the prop pitch command. 

Edited February 23, 2019 by Voyager

[Haza]

I would like to see Papafly actual test all of the aircraft!

[ZachariasX]

12 minutes ago, Haza said:

I would like to see Papafly actual test all of the aircraft!

You're asking a lot of him then. Especially without a robot pilot. But it would be also mostly academical, as for our practical purposes, the curves you get are largely similar (the aircraft perform similarish at similar power ratings) for the aircraft and you can roughly extrapolate depending on wing loading having this one curve. So you don't need to do all in detail.

 

That graph is good work.

[Haza]

It would just be interesting to see another one his videos. In saying that I would enjoy anybody's videos demonstrating the various FMs and comparing RL with in game figures.

 

Regards

[JtD]

Prop (pitch) and/or engine rpm have a major impact on the results and it's not really possible to make them meaningful comparable to real life figures or among each other in game.

[JG27*PapaFly]

On 2/23/2019 at 2:40 PM, Voyager said:

Could you walk me through what a polar chart is and how it's generated in this context?

 

I'd love to but I have no time due to real life obligations... Sorry

[Voyager]

53 minutes ago, JG27_PapaFly said:

 

I'd love to but I have no time due to real life obligations... Sorry

 

That's fine. It happens. I think I've tracked down Tacview, and am working on getting it set up and understanding it, probably wit the wing-overs first, then I'll move on to more direct test events from there.

[Voyager]

 

 

Current results on 3.010C. The glide slope seems reasonable. It is interesting that at speed, it appears to have only slightly more drag than the 190. I expect that that combination of low unloaded drag, combined with ludicrous engine power is what gives it its reputation as a diver

 

What is surprising is the range of AoA's in the full flaps tests, but I'm unsure of what, if any, the significance may be at this time.

[Haza]

Voyager

 

I would recommend that you go onto Berloga and record a few tracks.  You will be amazed at the number of players who can deploy flaps, climb vertically with no effort and still level off and then climb again, or even better, watch how the aircraft just floats on a cushion of air with full control surface authority!  However, watch it for yourself to believe it, before i'm accused of making things up!  My enjoyment of the game has now reached new lows and have lost interest in playing!  

 

Regards

 

 

Edited March 14, 2019 by Haza

[JG27*PapaFly]

On 3/3/2019 at 7:04 AM, Voyager said:

 

 

Current results on 3.010C. The glide slope seems reasonable. It is interesting that at speed, it appears to have only slightly more drag than the 190. I expect that that combination of low unloaded drag, combined with ludicrous engine power is what gives it its reputation as a diver

 

What is surprising is the range of AoA's in the full flaps tests, but I'm unsure of what, if any, the significance may be at this time.

The clean curve looks a bit strange. Is each data point in the diagrams a mean over several seconds of stable flight (stable speed and AOA)? That is very important and can be easily checked in tacview.

[Voyager]

29 minutes ago, JG27_PapaFly said:

The clean curve looks a bit strange. Is each data point in the diagrams a mean over several seconds of stable flight (stable speed and AOA)? That is very important and can be easily checked in tacview.

 

The low end of the curve is not very stable. 

 

The methodology I was going for was a long trimmed decent at the target speed, however the plane tended to want to go for the speeds it wanted to go for.

 

To really do this right I'd need to do several stabilised runs at each trim configuration, in the test load configuration, but given nothing truly weird turned up in the initial runs, I'm not sure it's going to yield much. 

 

At this point I suspect what people are seeing is what happens when you combine Fowler flaps with high engine power on a fast climbing aircraft. I'm thinking the historical inability of the P-47 to safely deploy flaps in dog fights prevented this sort of behavior from occurring in real life, but that, by the late war versions, if they could have used flaps in combat, we'd have seen the same sort of flap usage that turned up on the P-38 and P-51.

 

I'm also going to reiterate, according to the listed stats, the version of the Thunderbolt we have in game is one of the faster climbing aircraft currently in the game. At 18.1 m/s, 17.6 at 3km, it will beat every Russian fighter except the La-5+ at sea level, all Fw-190 at all altitudes, and even give most 109s a run for their money below 3km.

 

Also, the 18.1m/s is with full guns and 50% fuel ~6000kg,and one can generally pull another 500kg off of that if one wants to strip the plane for dog fighting. Most of the other climbers don't have that much extra payload that could be pulled off. 

 

This is a very different beast from the early versions.

Edited March 14, 2019 by Voyager

[RedKestrel]

9 hours ago, Haza said:

Voyager

 

I would recommend that you go onto Berloga and record a few tracks.  You will be amazed at the number of players who can deploy flaps, climb vertically with no effort and still level off and then climb again, or even better, watch how the aircraft just floats on a cushion of air with full control surface authority!  However, watch it for yourself to believe it, before i'm accused of making things up!  My enjoyment of the game has now reached new lows and have lost interest in playing!  

 

Regards

 

 

How would tracks on Berloga be any more valid than recording aircraft behaviour flying solo? Especially when lag effects on a crowded server can make planes behave really, really strangely.
 

 

17 minutes ago, Voyager said:

 

The low end of the curve is not very stable. 

 

The methodology I was going for was a long trimmed decent at the target speed, however the plane tended to want to go for the speeds it wanted to go for.

 

To really do this right I'd need to do several stabilised runs at each trim configuration, in the test load configuration, but given nothing truly weird turned up in the initial runs, I'm not sure it's going to yield much. 

 

At this point I suspect what people are seeing is what happens when you combine Fowler flaps with high engine power on a fast climbing aircraft. I'm thinking the historical inability of the P-47 to safely deploy flaps in dog fights prevented this sort of behavior from occurring in real life, but that, by the late war versions, if they could have used flaps in combat, we'd have seen the same sort of flap usage that turned up on the P-38 and P-51.

 

I'm also going to reiterate, according to the listed stats, the version of the Thunderbolt we have in game is one of the faster climbing aircraft currently in the game. At 18.1 m/s, 17.6 at 3km, it will beat every Russian fighter except the La-5+ at sea level, all Fw-190 at all altitudes, and even give most 109s a run for their money below 3km.

 

Also, the 18.1m/s is with full guns and 50% fuel ~6000kg,and one can generally pull another 500kg off of that if one wants to strip the plane for dog fighting. Most of the other climbers don't have that much extra payload that could be pulled off. 

 

This is a very different beast from the early versions.

So the issue we're seeing with flaps might just boil down to the fact that we can deploy flaps symmetrically, which was never possible in the real thing?

I know people talk alot about the low speed stall issues in the P-47  and I wonder if a lot of it isn't just overdone flap effects on lift combined with perfect synchronization of flap deployment, rather than the kind of fundamental broken-ness people assume. 

[Haza]

Just now, RedKestrel said:

How would tracks on Berloga be any more valid than recording aircraft behaviour flying solo? Especially when lag effects on a crowded server can make planes behave really, really strangely.
 

 

So the issue we're seeing with flaps might just boil down to the fact that we can deploy flaps symmetrically, which was never possible in the real thing?

I know people talk alot about the low speed stall issues in the P-47  and I wonder if a lot of it isn't just overdone flap effects on lift combined with perfect synchronization of flap deployment, rather than the kind of fundamental broken-ness people assume. 

 

RedKestrel,

 

I think the point that I was trying to make was is that there are players who are obviously aware of the issues with flaps and hence if you were to record it, you would see how wide spread this issue is!  Now I would agree that on a crowded server there may be some lag issues, however, in my time zone, whether the server is "crowded" or virtually empty, it matters not, as players apparently do it almost as a matter of course.

 

Regards

[JG27*PapaFly]

I still see the same global issues in the stall behaviour I documented in my vid:

- ailerons are too effective at critical AoA and beyond

- ailerons produce too little drag in those conditions

- planes can be recovered from spins with out-of-spin ailerons only, even if full in-spin rudder is applied

- aileron effectiveness is increased drastically when flaps are deployed

 

The net result is ufo-like plane behaviour and the widespread  use of tactics that were unthinkable in reality.

I'm a real-life pilot but to be honest I stopped using real-life control inputs to exit from spins. Instead, I apply full right rudder, full power, pull the stick all the way and apply out-of-spin ailerons: this method is always faster, providing instant recovery.

 

[Haza]

On 3/16/2019 at 4:01 AM, JG27_PapaFly said:

I still see the same global issues in the stall behaviour I documented in my vid:

- ailerons are too effective at critical AoA and beyond

- ailerons produce too little drag in those conditions

- planes can be recovered from spins with out-of-spin ailerons only, even if full in-spin rudder is applied

- aileron effectiveness is increased drastically when flaps are deployed

 

The net result is ufo-like plane behaviour and the widespread  use of tactics that were unthinkable in reality.

I'm a real-life pilot but to be honest I stopped using real-life control inputs to exit from spins. Instead, I apply full right rudder, full power, pull the stick all the way and apply out-of-spin ailerons: this method is always faster, providing instant recovery.

 

 

PapaFly,

 

I hear you mate!

However, don't be in a real aircraft and then think you are in WOL as you will get a shock if you deploy full flaps and expect to climb like a V2 rocket!

I'm sure the Devs will sort this flap issue out, sooner than later I hope!!!

 

Regards

[Haza]

Any news on the flaps issues?  I'm still watching the P-47 and Spit kicking out flaps and performing amazing feats in the air as previously discussed by PapaFly.

I'm just wondering whether the flap FM issues are just being brushed under the carpet?

[RedKestrel]

On 8/18/2019 at 12:44 AM, Haza said:

Any news on the flaps issues?  I'm still watching the P-47 and Spit kicking out flaps and performing amazing feats in the air as previously discussed by PapaFly.

I'm just wondering whether the flap FM issues are just being brushed under the carpet?

If the issues were being "brushed under the carpet" this thread wouldn't exist. The devs comment on things when they are working on them and are reasonably sure they can do it. Read the dev diaries and the patch notes. Its usually pretty clear.

If the flaps were worked on we would see it on the patch notes. There's been nothing like that for the last few updates. The devs are working on finalizing the FMs of the remaining planes for Bodenplatte. I wouldn't expect any major changes to the global flight modeling or other plane's flight model until final release.

[Cpt_Siddy]

All "good" players i have shot at use flaps, regardless of plane. (and vigorous stick onanism)

 

Ive seen certain players abuse flaps in Mig-3 and Yak's and in 109.  One of the worst offenders is 110, that can follow in steep climb from stand still speeds and put accurate fire down range. 

 

P-47 is just the latest and most hilarious addition to multiplayer scene that gets abused this way. Mainly owing to its powerful engine, 8 50. cals and kite-like handling with full flaps that makes it rather nasty dogfighter in the weeds. 

 

So this does deserve all the testing and documentation that is possible to done from the game side of the client. Good work! 

Edited August 23, 2019 by Cpt_Siddy

[56RAF_Roblex]

12 minutes ago, Cpt_Siddy said:

Ive seen certain players abuse flaps in Mig-3 and Yak's and in 109.

 

The fact that the Mig-3 was designed with the unique ability to pre-select a flap setting, say 25%, and then later in the flight drop the flaps instantly to that setting indicates to me that the flaps were expected to be used in combat.  You can still lower them to 25% gradually as with any other aircraft so this additional ability is surely for something other than landing.

[Cpt_Siddy]

19 minutes ago, 56RAF_Roblex said:

 

The fact that the Mig-3 was designed with the unique ability to pre-select a flap setting, say 25%, and then later in the flight drop the flaps instantly to that setting indicates to me that the flaps were expected to be used in combat.  You can still lower them to 25% gradually as with any other aircraft so this additional ability is surely for something other than landing.

 

Or it was a artifact that MiG-3 was over engineered and expensive by soviet standards. 

 

It was made to counter high altitude threats that never materialized.

[56RAF_Roblex]

14 minutes ago, Cpt_Siddy said:

 

Or it was a artifact that MiG-3 was over engineered and expensive by soviet standards. 

 

It was made to counter high altitude threats that never materialized.

 

That is not at all relevant to the discussion of flaps is it ?

[Cpt_Siddy]

16 minutes ago, 56RAF_Roblex said:

 

That is not at all relevant to the discussion of flaps is it ?

 

Actually, it is. If what you claim, is true, then the designers of MiG-3 intended flaps to be used in a way that may expose them to overspeed damage and any risk of potential asymmetric extension needs to be curbed down, same goes for risk of jamming.

 

If you can actually post some documentation on this, then this can help bring the behavior of flaps to more accurate place on MiG-3 or confirm it is there already.  

[56RAF_Roblex]

31 minutes ago, Cpt_Siddy said:

 

Actually, it is. If what you claim, is true, then the designers of MiG-3 intended flaps to be used in a way that may expose them to overspeed damage and any risk of potential asymmetric extension needs to be curbed down, same goes for risk of jamming.

 

If you can actually post some documentation on this, then this can help bring the behavior of flaps to more accurate place on MiG-3 or confirm it is there already.  

 

The flaps are purely gravity driven so unlikely to cause overspeed damage or jamming though the pilots notes do warn pilots of the risk of sudden change in AoA if they pop out fully as the speed drops and catch you unawares..  The odds of asymmetric extension (through combat damage I assume?) are no different to the odds with other aircraft where you might only find out as you turn finals on the edge of the stall.  1C does not model that event but they really should as it is quite exciting ?   

What documentation are you asking for.  Are you doubting that the Mig had a flap limiter?

Edited August 23, 2019 by 56RAF_Roblex
Misspell

[Cpt_Siddy]

16 minutes ago, 56RAF_Roblex said:

 

The flaps are purely gravity driven

 

But... how? 

 

16 minutes ago, 56RAF_Roblex said:

Are you doubting that the Mig had a flap limiter?

 

No, i am doubting that they saw such a wide spread use in actual combat compared to current MP scene. 

[56RAF_Roblex]

2 hours ago, Cpt_Siddy said:

2 hours ago, 56RAF_Roblex said:

 

The flaps are purely gravity driven

 

But... how? 

 

I was wrong. They are not *purely* gravity driven,  they have pneumatics but it is not very strong so will fail if there is too much resistance.   If you are travelling too fast the air flow will stop them opening as far as the stop/limiter but that is risky because when you slow down they might suddenly drop the rest of the way without warning.   Most of the other aircraft deploy the flaps using stronger pneumatics/ hydraulics so they will be forced open regardless of how fast you are flying and, as you say,  may get damaged or jammed.

 

As to doubting that they saw as much use in WW2 as they do here, That is a valid doubt and could be correct but  I think you need to re-read my original post.  What I said was that as the Mig designers put in a limiter when there was already a perfectly good way to lower the flaps for landing already present that "indicates to me that the flaps were expected to be used in combat."   'Indicates to me' means It was a supposition on my part, a guess if you prefer to use that word, that the limiter system was there for some other use than landing and combat was the most likely answer.  There is no need to ask for proof as I was putting forward a theory.  

[LLv34_Flanker]

S! 

 

This flaps flip flop is beyond a joke in IL-2. You lose a retracted flap easier in a dive than while abusing them in dogfight. From quite a few memoirs by pilots the use of flaps was very rare as the risk of damage and loss of speed was big. Not to mention having your hands full in controlling the plane while fighting, really no time for fiddling with a flap button/lever/wheel. 

 

I recall only one US plane having actual Combat flaps: P-38. From Japanese planes N1K2-J and Ki-84 had automatic Combat flaps. Germans had none while in 109 you could crank them out, but read that there was a mechanism preventing deployment at too high speed. Spitfire and Hurricane had no Combat settings whatsoever.. 

 

Hopefully the FM will be revised one day. 

 

 

[ZachariasX]

All the had to add was deformation damage when you extend them past permitted speeds. Nobody would pop flaps at high speed once they had flaps retract unevenly.

[Cpt_Siddy]

4 hours ago, LLv34_Flanker said:

S! 

 

This flaps flip flop is beyond a joke in IL-2. You lose a retracted flap easier in a dive than while abusing them in dogfight. From quite a few memoirs by pilots the use of flaps was very rare as the risk of damage and loss of speed was big. Not to mention having your hands full in controlling the plane while fighting, really no time for fiddling with a flap button/lever/wheel. 

 

I recall only one US plane having actual Combat flaps: P-38. From Japanese planes N1K2-J and Ki-84 had automatic Combat flaps. Germans had none while in 109 you could crank them out, but read that there was a mechanism preventing deployment at too high speed. Spitfire and Hurricane had no Combat settings whatsoever.. 

 

Hopefully the FM will be revised one day. 

 

 

 

 

What are you talking about!

 

It was very common place to 110 G-2 to follow La-5FN in to vertical climb with full flaps and scoring hits, i read many memoirs that show how this antigravity tech was used and then lost to history! Korkajännitys is very historical series! 

[LLv34_Flanker]

S! 

 

Siddy, do not reveal the almighty resource of Sikrit Dokjuments ? Korkeajännitys was supposed to be the Truth of All Time! 

[Dakpilot]

 Wildcat and Hellcat both had combat flaps, similar to Yak operation, but different so you will have to get used to it for whole war when Pacific comes ?

 

Cheers, Dakpilot 

[JtD]

No, they didn't. Because US flaps were subjected to the laws of physics and were automatically retracted above certain speeds to avoid mishaps of all sorts.

 

The F6F also had slotted flaps, not split flaps. They were hydraulically extended to the low position, and rotated around the fixed, lowered axis (were not pushed back up) when exposed to air pressure. They angle was about 50° at low speed and 15° at 150 knots. They were automatically retracted at 170 knots, 315 km/h.

 

Nothing like in game Yak flaps, at all.

Edited September 12, 2019 by JtD

[Cpt_Siddy]

6 hours ago, JtD said:

No, they didn't. Because US flaps were subjected to the laws of physics

 

This is the most un american statement i have ever heard! 

 

If US wanted to make flaps that defy gravity, they make them. Because US law supersede other laws.

 

But on more serious note, there might be some sort shortcoming when it comes modelling flaps on powerful aircrafts like 110 G-2, P-47 and such.

 

When the air speed drops at certain level, the drag from flaps drop to near 0 and gets full benefit from the strong engines without drag losses.

P-40 does not suffer from over effective flaps, nor does P-39.  

Edited September 12, 2019 by Cpt_Siddy

[Dakpilot]

3 hours ago, JtD said:

No, they didn't. Because US flaps were subjected to the laws of physics and were automatically retracted above certain speeds to avoid mishaps of all sorts.

 

The F6F also had slotted flaps, not split flaps. They were hydraulically extended to the low position, and rotated around the fixed, lowered axis (were not pushed back up) when exposed to air pressure. They angle was about 50° at low speed and 15° at 150 knots. They were automatically retracted at 170 knots, 315 km/h.

 

Nothing like in game Yak flaps, at all.

 

I think I said similar but different... 

 

Do they both not automatically get retracted above certain speeds to avoid damage? 

 

My reply was aimed at the ' I recall only one US plane with actual combat flaps' 

Wheras combat flaps and use of featured heavily throughout the whole Pacific war

 

I think I will leave you guys to it ?

 

Cheers, Dakpilot 

[JtD]

8 hours ago, Dakpilot said:

Do they both not automatically get retracted above certain speeds to avoid damage?

 

No, Yak flaps don't. They are getting pushed up.

 

8 hours ago, Dakpilot said:

My reply was aimed at the ' I recall only one US plane with actual combat flaps' 

Wheras combat flaps and use of featured heavily throughout the whole Pacific war

 

How much combat against the Japanese do you think was fought at speeds below 170 knots?

And why does a system that prevents damage to a landing aid automatically turn it into 'actual combat flaps'?