NachtJaeger110 Posted August 20, 2015 Posted August 20, 2015 (edited) Wouldn't it be sufficient to show the Devs that it is aerodynamically impossible that any plane could achieve a decrease in sustained turn time by deploying flaps in a turn at ground level? The FM guys must be engineers after all and must know their aerodynamics, if something is impossible in theory, they won't require RL data on the Yak1 flaps to fix their behavior. Edited August 20, 2015 by NachtJaeger110
Maxyman Posted August 20, 2015 Posted August 20, 2015 Are the flaps of the Yak 9 different to the ones on the Yak 1? Because if not we could try asking the guys at Hanger 10 about the flaps system, they have a Yak 9 in flying condition. Yak-1 and Yak-9 flaps are identical.
indiaciki Posted August 20, 2015 Posted August 20, 2015 This shows increased turn rate at airspeeds around 130mph at 12000ft if I read correctly?
DD_Arthur Posted August 20, 2015 Posted August 20, 2015 With all respect to Bert I think these Spitfire "documents" are rather irrelevant to a Yak-1 discussion. Spitfire flaps were positively locked in the down position. There was no "blow back" mechanism fitted and flaps were retracted by a dampened spring assembly with a 400lb/in rating. Also - in respect of the charts - no Spitfire ever built had the capability to deploy flaps at either 30 or 60 degrees. When they were up, they were up and when they were down they were at 85 degrees and thats it.
JtD Posted August 20, 2015 Posted August 20, 2015 For what its worth I have a fair bit of time in the YAK52 and Nanchang CJ6 both have pneumatic single stage (Up/Down) flaps. Neither of them have any blow back or flap load relief system. Both have Flap limit speeds. Bashing flaps out above these speeds on these types will bend something. Thanks Bert, again for the Spitfire documents and also for sharing your knowledge about other pneumatic flaps. I hope everyone was listening.
JtD Posted August 20, 2015 Posted August 20, 2015 Wouldn't it be sufficient to show the Devs that it is aerodynamically impossible that any plane could achieve a decrease in sustained turn time by deploying flaps in a turn at ground level? It's not impossible theoretically and Bert has just given an example where flaps deployment increased turn time. It's calculated data and not spot on, but it clearly illustrates the theory behind it.
JtD Posted August 20, 2015 Posted August 20, 2015 This shows increased turn rate at airspeeds around 130mph at 12000ft if I read correctly?No, 30° flaps already help at 200 mph TAS at 12000'. The lines in the "Turns maintaining altitude" chart cross at about that speed, below that speed 30° flaps permit higher g, so less turn time and tighter radius.
NachtJaeger110 Posted August 20, 2015 Posted August 20, 2015 (edited) It's not impossible theoretically and Bert has just given an example where flaps deployment increased turn time. It's calculated data and not spot on, but it clearly illustrates the theory behind it. You meant "decreased turn time" right? -> What can be seen is flap 30 does provide an improved sustained turn rate (smaller turn time). Taking the intersection of Ps=0 line with the lift limit gives a turn time clean of around 19secs (18.84deg sec). Looking at the same point with Flaps 30 gives a Turn time of around 17secs (21.2 deg sec). But as 5tuka pointed out, the last chart shows that in the spitfire test, altitude was traded off for airspeed during the turn, which PeterZvan in his test could not do because he flew on the deck. There was no way to get this extra airspeed. I assumed that the spitfire's turn time with flaps down would have increased if it was also performed very low. Edited August 20, 2015 by NachtJaeger110
JtD Posted August 20, 2015 Posted August 20, 2015 (edited) You meant "decreased turn time" right?Yes, I did, thanks for noticing. The chart 5tuka is discussing are any sustained turns at stall speed. Best sustained level turn is just when the the rate of climb line meets level flight, the zero line. While the speed is lower for the flaps down variants here, flaps down have a higher lift coefficient and allow a tighter turn radius. Flaps down: Higher lift coefficient, slower speed - tighter turn radius and in this case, seen on other charts, better sustained turn time, lower sustained g. Flaps up: Lower lift coefficient, higher speed - wider turn radius and in this case, seen on other charts, worse sustained turn time, higher sustained g. Edited August 20, 2015 by JtD
Bert_Foster Posted August 20, 2015 Posted August 20, 2015 (edited) DD Arthur we know about Spit flaps being single stage. The RAF report is based on calculation using Spitfire data. Now with respect to YAK Flap design. I have a close friend who maintains (runs an aircraft restoration/maintenance company) various warbirds and also flys multiple types. One aircraft in his charge (and he flies) is one of the new YAK3 re builds powered by the Allison engine. I posed the following question to him: " C....... a curly one for you Is there any Flap load relief system in the Yak 3 ? By that I mean what happens if you select Full flap then accelerate the aeroplane ? Will the Flap progressively blow black as the Air load increases ? Or if say you are running at high speed and bang the flaps out what happens? Do they just deploy a little or attempt to go full throw and something gets bent ?" His response: "Nothing like that on the yak 3 deployed at high speed I'm sure they would remove them selves and hopefully both at the same time" Edited August 20, 2015 by Bert_Foster 2
NachtJaeger110 Posted August 20, 2015 Posted August 20, 2015 Man, this email and the spit test.. that is some great research Bert! Any chance getting some technical data or plans on the Yak3 flaps from your friend? that along with his statement would make a great argument to send to the devs
Bert_Foster Posted August 20, 2015 Posted August 20, 2015 (edited) Some more data for those that want to discuss Flap effects on turning. This from a NACA test on the F2A (Buffalo) A similar conclusion to the Spit report. The full report in the attached pdf for those that want to wade through it. F2A3_turning.pdf Edited August 20, 2015 by Bert_Foster 1
Maxyman Posted August 21, 2015 Posted August 21, 2015 Man, this email and the spit test.. that is some great research Bert! Any chance getting some technical data or plans on the Yak3 flaps from your friend? that along with his statement would make a great argument to send to the devs But what are you going to email? The report confirms that the flaps behaviour is accurate: - Angle of climb is modelled - Turn rate/radius change is modelled - The conclusion is pretty much is what we have in the game.
=EXPEND=Tripwire Posted August 21, 2015 Posted August 21, 2015 (edited) But what are you going to email? I believe he was referring to the possibility that the yak flaps were an all or nothing deployment. " C....... a curly one for you Is there any Flap load relief system in the Yak 3 ? By that I mean what happens if you select Full flap then accelerate the aeroplane ? Will the Flap progressively blow black as the Air load increases ? Or if say you are running at high speed and bang the flaps out what happens? Do they just deploy a little or attempt to go full throw and something gets bent ?" His response: "Nothing like that on the yak 3 deployed at high speed I'm sure they would remove them selves and hopefully both at the same time" Edited August 21, 2015 by Tripwire
Maxyman Posted August 21, 2015 Posted August 21, 2015 "Nothing like that on the yak 3 deployed at high speed I'm sure they would remove them selves and hopefully both at the same time" Isn't it what we have in the game? In the early access days Yak flaps would remove themselves completely at around 250kmh. That's only if the lever is down, if it's in the neutral position, you can retract flaps by hand.
JtD Posted August 21, 2015 Posted August 21, 2015 Thanks for the F2A report. It's interesting to note that in this case flaps deployment increases sustained turn time. So the two reports cover all possibilities. Also good to know that a real life Yak pilot shares my opinion about their behaviour in a high speed deployment.
Bert_Foster Posted August 21, 2015 Posted August 21, 2015 Maxyman you are "cherrypicking" with just one line from the RAF report Its not as simple as that. As I indicated in my summary a few posts up with a basic summary of how I see the problem. Flaps can help turning performance in specific arenas but they can hurt your turn performance in other arenas. The real issue now id the mechanics of the YAK 1 Flap system modelled correctly in BOS. 1. At present it effectively has a Blow back or Flap load relief system. 2. Initial enquiry to YAK3 maintainer/pilot says the YAK 3 doesn't have such a system .... so Flap extension above limit speeds will cause some degree of damage. A cursory look through Anglicised version of the VVS YAK 3 manual implies a a Flap limit speed of 240kmh. Question is is the YAK 1 Flap system the same ? Based on what I have seen so far The YAK 1 Flap system is incorrectly modelled. I believe it shouldn't blow back and if deployed above limit speeds or left extended should get damaged .... as other aircraft in the sim do. Happy to be proven wrong on the YAK 1 Flap design/mechanics
indiaciki Posted August 21, 2015 Posted August 21, 2015 (edited) Once again. Flaps are for Landings and Take offs. They were not designed for high speeds. There might have been combat flaps (wildcat / bearcat) but not in europe. Flaps above certain speeds cause serious damage. + they cause drag - decrease speed, bleed energy that is needed in combat. Nobody would trade turn rates for energy (speed, climb) in combat. Even in a turn fight. Flaps slow down and they are used to decrease stall speed and increase AoA. If 240 km/h is your combat speed in a fighter you could as well dogfight in a JU 87. Edited August 21, 2015 by indiaciki
Maxyman Posted August 21, 2015 Posted August 21, 2015 (edited) The real issue now id the mechanics of the YAK 1 Flap system modelled correctly in BOS.1. At present it effectively has a Blow back or Flap load relief system. 2. Initial enquiry to YAK3 maintainer/pilot says the YAK 3 doesn't have such a system .... so Flap extension above limit speeds will cause some degree of damage. A cursory look through Anglicised version of the VVS YAK 3 manual implies a a Flap limit speed of 240kmh. Question is is the YAK 1 Flap system the same ? 1. There is no blow back, you are right. But the pressure in the cylinder is constant - 32bar, the airflow pressure is varied. At some point, the airflow pressure will be pushing the flaps back. This scenario was calculated on the Russian forum - http://forum.il2sturmovik.ru/topic/817-letnaya-model-i-model-povrezhdenij/?p=174832 2. Original Yak-1 only states "The flaps should be retracted at a speed not less than 250kmh". There is no explicit speed limit. Real Yak fighter pilots were using flaps when attacking bombers (usually at 350-450kmh). I agree that the flaps are indestructible in the game. That seems to be the only issue. I see it as a simplification. Edited August 21, 2015 by Maxyman
Bert_Foster Posted August 21, 2015 Posted August 21, 2015 I can accept that if the flaps are deployed and the flap handle is then placed in the neutral position, air loads will push the flaps in, but they will as a function of air load go all the way in. There is no method to allow them to say come back to a small deflected position and stay there. As to use in the 350-450kmh range why ?
Bearcat Posted August 21, 2015 Posted August 21, 2015 Once again. Flaps are for Landings and Take offs. They were not designed for high speeds. There might have been combat flaps (wildcat / bearcat) but not in europe. Flaps above certain speeds cause serious damage. + they cause drag - decrease speed, bleed energy that is needed in combat. Nobody would trade turn rates for energy (speed, climb) in combat. Even in a turn fight. Flaps slow down and they are used to decrease stall speed and increase AoA. If 240 km/h is your combat speed in a fighter you could as well dogfight in a JU 87. They may not have been designed for high speeds but they were used.. I spoke to Bud Anderson in Reading Pa. at a WWII weekend some years back... and he said, and I am paraphrasing a bit because i don't remember exactly what he said. , when you were flying in combat you used whatever was on the plane.. regardless to what the design was or what the books said.. He said "We used flaps, trim, pitch, throttle.. whatever we had on that aircraft to come home alive and kill the other guy before he could kill you.. It was war.. " he also said that they learned the limitations of their planes.... and pushed them there as close as they could get.. and sometimes beyond... so this idea about what "flaps were for" is armchair rhetoric. Yeager was famous for that.. on just about every mission where there was an engagement with enemy fighters he brought his bird back with popped rivets, bent flaps, never with left over ammo... Yes deploying flaps beyond a certain point was suicide.. because if they locked on you and you could not retract them you were done if in a fight.. but these guys that we celebrated used every inch of the weapon they were flying to come home alive because that was what it was all about. 1
Maxyman Posted August 21, 2015 Posted August 21, 2015 (edited) I can accept that if the flaps are deployed and the flap handle is then placed in the neutral position, air loads will push the flaps in, but they will as a function of air load go all the way in. There is no method to allow them to say come back to a small deflected position and stay there. It has to be proven. Say there’s a maximum speed Vf, flaps can be fully released at. What happens if an aircraft exceeds this speed? The pressure in the system increases, flaps are pushed back The pressure in the system decreases, there is a leak, flaps are pushed back Mechanical damage. As to use in the 350-450kmh range why ? The optimal range to engage Ju-87 and Ju-88 at cruise speed. Edited August 21, 2015 by Maxyman
JtD Posted August 21, 2015 Posted August 21, 2015 ... This scenario was calculated on the Russian forum - http://forum.il2sturmovik.ru/topic/817-letnaya-model-i-model-povrezhdenij/?p=174832... Great, finally some prove there's neither drag nor friction in Yak-1 flaps. Of course only if you believe that calculation to show the complete picture.
Maxyman Posted August 21, 2015 Posted August 21, 2015 (edited) Great, finally some prove there's neither drag nor friction in Yak-1 flaps. Of course only if you believe that calculation to show the complete picture. Let's stay constructive. Yes, there is no friction, that's a fair point. It was an approximation to prove that the initial model was incorrect. Can you calculate the friction? We can neglect the friction, if the pressure in the system is 1 bar. What happens if the pressure increases? Edited August 21, 2015 by Maxyman
Bert_Foster Posted August 21, 2015 Posted August 21, 2015 Ok 350-450kmh a good fighting speed .... but as the supplied docs have shown flap at these speeds is going to hurt your turn performance ! The only real regime where you get benefit from small flap deflection is on or very near the lift limit . Scissors v another fighter would be a good example. Slashing attacks on Transports/Bombers is not going to be done at slow speeds or close to the lift limit. It makes no sense to be adding drag to your fighter whilst trying to hit and tun Attacking larger transport aircraft at a good energy speed (350-450) makes a whole lot of sense, but using flaps at these speeds just doesn't make any sense. Now as to YAK pneumatic flaps. The only time you dont have pressure in the system is when the lever is in neutral.
Maxyman Posted August 21, 2015 Posted August 21, 2015 Ok 350-450kmh a good fighting speed .... but as the supplied docs have shown flap at these speeds is going to hurt your turn performance ! The only real regime where you get benefit from small flap deflection is on or very near the lift limit . Scissors v another fighter would be a good example. Slashing attacks on Transports/Bombers is not going to be done at slow speeds or close to the lift limit. It makes no sense to be adding drag to your fighter whilst trying to hit and tun Attacking larger transport aircraft at a good energy speed (350-450) makes a whole lot of sense, but using flaps at these speeds just doesn't make any sense. Unfortunately, I don’t have an answer. I can only guess that in some cases it’s worth to sacrifice altitude and speed to reduce turn radius. My initial sentence was ambiguous, there should’ve been two separate: - Optimal speed to attack bombers – 350-450 - Sometimes pilots used flaps when attacking bombers (not necessarily at 350-450). Now as to YAK pneumatic flaps. The only time you dont have pressure in the system is when the lever is in neutral. I've never argued with that
Dakpilot Posted August 21, 2015 Posted August 21, 2015 +1 Maxyman for link to the information and diagrams on the Yak flap system http://forum.il2stur...denij/?p=174832 Cheers Dakpilot
Bert_Foster Posted August 21, 2015 Posted August 21, 2015 +1 Maxyman for link to the information and diagrams on the Yak flap system http://forum.il2stur...denij/?p=174832 Cheers Dakpilot Link doesnt work for me can it be re posted please ?
Dakpilot Posted August 21, 2015 Posted August 21, 2015 Sorry, I just copied the link from post #183 it works there, you must re-log into RU forum, this info was posted a year ago....would have avoided a lot of speculation, it is only from proper info that any deductions can be made Cheers Dakpilot
JtD Posted August 21, 2015 Posted August 21, 2015 Sorry, I just copied the link from post #183 it works there, you must re-log into RU forum, this info was posted a year ago....would have avoided a lot of speculation, it is only from proper info that any deductions can be made Cheers Dakpilot Yes, and still you are often on of the first to speculate while hardly ever presenting proper info. Let's stay constructive. Yes, there is no friction, that's a fair point. It was an approximation to prove that the initial model was incorrect. Can you calculate the friction? We can neglect the friction, if the pressure in the system is 1 bar. What happens if the pressure increases? I agree, this is a good illustration of the working principle. But if you were referring to this calculation when you said something about 5-6° at 700 IAS, I'd say this is far outside purpose of that estimate. About friction, you'd need data to estimate it, down to the precision of the bearings, lubricant, stiffness of material, accuracy of assembly and so on. Imho, impossible to predict reasonably accurate from theoretical data. You can't neglect friction under any circumstances. Even well maintained control surfaces required pilot inputs of several N to be moved at all, in most aircraft for most controls, it were several dozen N. You can expect no less from a flaps system design to operate under forces of several thousand N. And it's going to get worse when several thousand N are indeed applied.
Dakpilot Posted August 21, 2015 Posted August 21, 2015 Yes I often speculate, usually when someone presents a claim as a fact, but I never claim my speculation is fact Cheers Dakpilot
indiaciki Posted August 21, 2015 Posted August 21, 2015 (edited) He said "We used flaps, trim, pitch, throttle.. whatever we had on that aircraft to come home alive and kill the other guy before he could kill you.. It was war.. " he also said that they learned the limitations of their planes.... and pushed them there as close as they could get.. and sometimes beyond... Yes deploying flaps beyond a certain point was suicide.. because if they locked on you and you could not retract them you were done if in a fight.. but these guys that we celebrated used every inch of the weapon they were flying to come home alive because that was what it was all about. You have a real point. So the problem seems to be the damage model. Stress is not modeled right. At least some random failures cause by stress on structure Edited August 21, 2015 by indiaciki
TWC_Ace Posted August 21, 2015 Posted August 21, 2015 (edited) They may not have been designed for high speeds but they were used.. I spoke to Bud Anderson in Reading Pa. at a WWII weekend some years back... and he said, and I am paraphrasing a bit because i don't remember exactly what he said. , when you were flying in combat you used whatever was on the plane.. regardless to what the design was or what the books said.. He said "We used flaps, trim, pitch, throttle.. whatever we had on that aircraft to come home alive and kill the other guy before he could kill you.. It was war.. " he also said that they learned the limitations of their planes.... and pushed them there as close as they could get.. and sometimes beyond... so this idea about what "flaps were for" is armchair rhetoric. Yeager was famous for that.. on just about every mission where there was an engagement with enemy fighters he brought his bird back with popped rivets, bent flaps, never with left over ammo... Yes deploying flaps beyond a certain point was suicide.. because if they locked on you and you could not retract them you were done if in a fight.. but these guys that we celebrated used every inch of the weapon they were flying to come home alive because that was what it was all about. Are you seriously trying to "justify" constant flaps exploit with yaks flaps (reffering to the slow energy bleed and undestructability all the way up to 700 kmh). It was dangerous thing to do in US planes at higher speeds and definitely suicide in earlier vvs planes...for sure...In RL deploying flaps (even more true at higher speeds) in combat would be very daring move since it would bring instability to the plane, possibility of braking or jamming them, slowing up your plane considerably (not so with yak in the game now), loosing energy in the middle of the battle etc...Do we have this in the sim with yak? According to teh test shown here - nope...Why? Edited August 21, 2015 by blackram_ 1
Brano Posted August 21, 2015 Posted August 21, 2015 Have any of you specialists ever seen Yak-1 manual and is pneumatics drawings? Construction of flaps? Someone here mocked about them being made of plywood @#€%.Well,be surprised,they were made of duraluminium.Do the ailerons on yak bend or tear off at 500 or 600km/h? Why should flaps? Are they attached to the wing spars by sticky tape? I have seen till now only speculations and doubtfull tests instead of drawing of yak pneumatic system and explanation of its functionality. Have any of you specialists ever seen Yak-1 manual and its pneumatics drawings? Construction of flaps? Someone here mocked about them being made of plywood @#€%.Well,be surprised,they were made of duraluminium.Do the ailerons on yak bend or tear off at 500 or 600km/h? Why should flaps? Are they attached to the wing spars by sticky tape? I have seen till now only speculations and doubtfull tests instead of drawing of yak pneumatic system and explanation of its functionality.
TWC_Ace Posted August 21, 2015 Posted August 21, 2015 Have any of you specialists ever seen Yak-1 manual and is pneumatics drawings? Construction of flaps? Someone here mocked about them being made of plywood @#€%.Well,be surprised,they were made of duraluminium.Do the ailerons on yak bend or tear off at 500 or 600km/h? Why should flaps? Are they attached to the wing spars by sticky tape? I have seen till now only speculations and doubtfull tests instead of drawing of yak pneumatic system and explanation of its functionality.Have any of you specialists ever seen Yak-1 manual and its pneumatics drawings? Construction of flaps? Someone here mocked about them being made of plywood @#€%.Well,be surprised,they were made of duraluminium.Do the ailerons on yak bend or tear off at 500 or 600km/h? Why should flaps? Are they attached to the wing spars by sticky tape? I have seen till now only speculations and doubtfull tests instead of drawing of yak pneumatic system and explanation of its functionality. lets say yaks flaps were state of art durability...but whats about energy bleed or significant drop of speed while having them lowered?
Brano Posted August 21, 2015 Posted August 21, 2015 Fly yak at 3k at 500km/h,extend flaps.Check the speed you slowed down to. Fly messer under same conditions and extend flaps.Come back with the results.And that remark about "state of art flaps" of yak....no comment
Bert_Foster Posted August 21, 2015 Posted August 21, 2015 Did a simple YAK1 Flap drag test results posted without comment: TEST YAK1 50% Fuel Sea level Power Max Boost RPM 2650 RADS both full open ACCEL TEST 250Kmh Start 1min later achieved 520Kmh Clean 250Kmh start 1min obtained 380Kmh starting accel with Full Flaps DECEL TEST From 520Kmh took 51seconds to decel to 250Kmh Full Flap took 28secs to decel from 520Kmh to 250Kmh* *Method for flap decel test: smooth descent from 300m to sea level to establish 540Kmh then selected Idle and flap started clock as IAS went through 520Kmh Flap deflection as per BOS design increased with reducing aerodynamic load.
Art Posted August 21, 2015 Posted August 21, 2015 OK Yak flaps are broken. So send message Han or Zak. Im waiting for fix!
Maxyman Posted August 22, 2015 Posted August 22, 2015 Did a simple YAK1 Flap drag test results posted without comment: TEST YAK1 50% Fuel Sea level Power Max Boost RPM 2650 RADS both full open ACCEL TEST 250Kmh Start 1min later achieved 520Kmh Clean 250Kmh start 1min obtained 380Kmh starting accel with Full Flaps DECEL TEST From 520Kmh took 51seconds to decel to 250Kmh Full Flap took 28secs to decel from 520Kmh to 250Kmh* *Method for flap decel test: smooth descent from 300m to sea level to establish 540Kmh then selected Idle and flap started clock as IAS went through 520Kmh Flap deflection as per BOS design increased with reducing aerodynamic load. Could you please comment on that? F4 accelerates to 370 with full flaps in ~30 seconds, decelaretes from 520 to 250 in 25. Where do you see a problem with Yak-1 flaps?
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