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=EXPEND=13SchwarzeHand

Speed loss during turn yak vs 109

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Do this: take a yak or a 109 with standard stab/trim settings. Speed up to 600kph during a dive. Then do a 180 degree turn. The test set up is relatively easy when you turn on HUD incl. compass.

In the turn the yak will loose 40-50 kph the pilot will black out.

the 109 will loose 80-100 kph

What is the reason for this relatively big discrepancy? Obviously the yak pulls mir G than the 109

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'Yak'? Which one? '109'? Which one? Altitude? Altitude lost in the turn? Rate of turn? Fuel load? ... Too many unknowns to give a useful answer, though I suspect that wing loading comes into it.

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Posted (edited)

Fuel 100L

F4

Yak1

Bank 90 degrees and pull as hard as you can. Altitude loss is negligible

 

just sense checking... info should suffice for sense checking

Edited by =EXPEND=13BumaYe

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If you can turn through 180 degrees at a 90-degree bank without losing altitude, there is something seriously wrong.

 

If you want a meaningful analysis, rather than vague opinions, I think we need proper data. If you haven't already, download TacView and post recordings.

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Posted (edited)

like I said, alt loss is the same for both planes, never said it didn’t exist just that it’s negligible in terms of differentiation. 

 

I am simply asking where the difference of 100% extra speed loss for the 109 comes from in an identical maneuver for 2 planes. I don’t need to provide data, not making an fm claim... everyone can do the test easily 

Edited by =EXPEND=13BumaYe

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Typically pulling more g's gets you through a high speed turn with less speed loss. Since the Yak can pull more g's at higher speeds, it should come through the turn quicker and end up faster. That's just physics.

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19 hours ago, JtD said:

Typically pulling more g's gets you through a high speed turn with less speed loss. Since the Yak can pull more g's at higher speeds, it should come through the turn quicker and end up faster. That's just physics.

 

More G => greater Angle of Attack => more Induced Drag => less speed.

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If Is not the Yak-7 wich Is the Yak with better response on game, over 600, without trim Yak its almost a brick. That could explain a little of the retention of energy. 109 its also pretty bricky but only when you forget to trim correctly.

 

But. It would be nice a track record with historical data of energy retention on high speed turns

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1 hour ago, SCG_OpticFlow said:

More G => greater Angle of Attack => more Induced Drag => less speed.

 

Yeah, I know. Seems counter-intuitive that you end up faster if you pull more g's in a short high speed turn. But at 600 (indicated, I assume), if you don't black out, you're producing way more parasitic then induced drag, and that over a longer period of time, and are therefore flying way below best performance.

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On 7/6/2019 at 8:51 PM, =EXPEND=13BumaYe said:

Do this: take a yak or a 109 with standard stab/trim settings. Speed up to 600kph during a dive. Then do a 180 degree turn. The test set up is relatively easy when you turn on HUD incl. compass. 

In the turn the yak will loose 40-50 kph the pilot will black out.

the 109 will loose 80-100 kph 

What is the reason for this relatively big discrepancy? Obviously the yak pulls mir G than the 109

 

Are your turns coordinated?

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12 hours ago, SCG_OpticFlow said:

 

Are your turns coordinated?

 

A slip indicator not perfectly centered doesn't change anything (I mean it's negligible).

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About the speed loss in a turn, wing load could be one of the explanation. May be also the wing profile... Just suggestions, I'm not an aerodynamic engineer :)

 

Yak1b: 

2887kg / 17.15m² = 168kg/m²

 

Bf109G2:

2994kg/16.1m² = 186kg/m²

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On 7/6/2019 at 10:14 PM, JtD said:

Typically pulling more g's gets you through a high speed turn with less speed loss. Since the Yak can pull more g's at higher speeds, it should come through the turn quicker and end up faster. That's just physics.

 

Yes, thank you that makes perfect sense. It’s the magnitude of difference that just seems counterintuitive to me...

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Posted (edited)
On 7/6/2019 at 1:51 PM, =EXPEND=13SchwarzeHand said:

Do this: take a yak or a 109 with standard stab/trim settings. Speed up to 600kph during a dive. Then do a 180 degree turn. The test set up is relatively easy when you turn on HUD incl. compass.

In the turn the yak will loose 40-50 kph the pilot will black out.

the 109 will loose 80-100 kph

What is the reason for this relatively big discrepancy? Obviously the yak pulls mir G than the 109

the problem is the standard trim settings. If the stab on the 109 is set to the default negative 70 or whatever it is, it retards pitch control. You have to trim to neutral and then you can pull a ton of G.

 

When I fly the 109 I fly at 0--35% stab so that I can turn hard if suddenly bounced. I only trim negative when I know I am going to dive on something or need speed.

 

I think the reason this happens is that due to the fact that the negative stab trim changes the position of the elevator at neutral stick, max stick deflection results in less upward elevator deflection at negative trim.

Edited by Fumes

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Looks weird to me. Is like turning on a car. If you make a very tight turn you lose more speed because you lose a lot of energy due to centry force. 

On my opinion we need a review of the Fm regarding the energy rentention of the planes on manouvers and  taking weight as well on zooms, dives  etc. 

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1 hour ago, E69_geramos109 said:

Looks weird to me. Is like turning on a car. If you make a very tight turn you lose more speed because you lose a lot of energy due to centry force. 

On my opinion we need a review of the Fm regarding the energy rentention of the planes on manouvers and  taking weight as well on zooms, dives  etc. 

 

There are two things at work here, parasitic drag and lift induced drag.

 

The former increases with the square of the surrounding medium's flow velocity.


F_{D}\,=\,{\tfrac  12}\,\rho \,u^{2}\,C_{D}\,A

 

The latter increases with the square of the lift generated and decreases with increasing airspeed and wingspan.

 

8d8aa7e10ac52ad91c0d3b7dcd126bde0f948fe6


This gives us the following curves:

 

Spoiler

1920px-Drag_curves_for_aircraft_in_fligh

 

So yeah, it's totally possible a plane could do a 180 in less time and lose less energy than another plane starting at the same airspeed that's trying and failing to keep up with the former's vertical acceleration.

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Posted (edited)
1 hour ago, PainGod85 said:

 

There are two things at work here, parasitic drag and lift induced drag.

 

The former increases with the square of the surrounding medium's flow velocity.


F_{D}\,=\,{\tfrac  12}\,\rho \,u^{2}\,C_{D}\,A

 

The latter increases with the square of the lift generated and decreases with increasing airspeed and wingspan.

 

8d8aa7e10ac52ad91c0d3b7dcd126bde0f948fe6


This gives us the following curves:

 

  Hide contents

1920px-Drag_curves_for_aircraft_in_fligh

 

So yeah, it's totally possible a plane could do a 180 in less time and lose less energy than another plane starting at the same airspeed that's trying and failing to keep up with the former's vertical acceleration.

But you are talking just about drag. I was refearing to the lose of energy by pulling Gs because the force wants to pull out of the turn and the plane wants to go the other direction. thighter the more energy you need to make it so you lose more energy pulling 5 gs than pulling 2 gs 

Maybe that balances because pulling less gs you need more time to make the 180 turn (not sure if is enought someone with better phisics can say more than me) Maybe is good to make the test the same way but instead looking at degrees looking at time. on 4 secs how much energy loses the yak and on the same time how much energy loses the 109.  maybe the result will be different

Edited by E69_geramos109

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9 hours ago, E69_geramos109 said:

But you are talking just about drag. I was refearing to the lose of energy by pulling Gs because the force wants to pull out of the turn and the plane wants to go the other direction. thighter the more energy you need to make it so you lose more energy pulling 5 gs than pulling 2 gs 

Maybe that balances because pulling less gs you need more time to make the 180 turn (not sure if is enought someone with better phisics can say more than me) Maybe is good to make the test the same way but instead looking at degrees looking at time. on 4 secs how much energy loses the yak and on the same time how much energy loses the 109.  maybe the result will be different

 

Yes, that's lift induced drag. You increase lift because you suddenly have to accelerate that plane not by the opposite force of earth's gravity, but several times that. Concurrently, lift induced drag (= the loss of energy by pulling Gs) peaks. This causes the local minimum for the total drag curve to shift into a higher speed regimen.

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Posted (edited)

 

 

Just remembered that something principally similar has already been discussed in depth.

 

Haven’t seen the new data for the yak 7 and I find it strange that it exceeds the already superb results of the other yaks.

 

But it only supports the impression that I get from the game already.

 

Edited by =EXPEND=13SchwarzeHand

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1 hour ago, PainGod85 said:

 

Yes, that's lift induced drag. You increase lift because you suddenly have to accelerate that plane not by the opposite force of earth's gravity, but several times that. Concurrently, lift induced drag (= the loss of energy by pulling Gs) peaks. This causes the local minimum for the total drag curve to shift into a higher speed regimen.

Yes that lift induced drag increases because the lift is what makes the plane to fight as well with the gs. but there are more events on a turn that causes the lose of energy. Imagine a ball without wings that has an amount of speed and energy. If the ball turns on an the void space with no air and with any kind of drag force the ball is going to lose some energy on the turn so it loses speed on the process and to keep the speed it need some kind of source power. That is the same for any kind of object and on our case we have a plane with an air profile, wings, engine, weight that makes helps or adds more energy lose to the ecuation. 

 

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2 hours ago, E69_geramos109 said:

Yes that lift induced drag increases because the lift is what makes the plane to fight as well with the gs. but there are more events on a turn that causes the lose of energy. Imagine a ball without wings that has an amount of speed and energy. If the ball turns on an the void space with no air and with any kind of drag force the ball is going to lose some energy on the turn so it loses speed on the process and to keep the speed it need some kind of source power. That is the same for any kind of object and on our case we have a plane with an air profile, wings, engine, weight that makes helps or adds more energy lose to the ecuation. 

 

 

What are you even on about?

 

The question was whether it could be energetically advantageous to pull a short, high G turn instead of a longer, low G turn to achieve a desired change in direction.

 

That answer is 'yes'.

 

 

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Posted (edited)
5 hours ago, E69_geramos109 said:

 If the ball turns on an the void space with no air and with any kind of drag force the ball is going to lose some energy on the turn so it loses speed on the process and to keep the speed it need some kind of source power.

 

As long as the force generating the turn is perpendicular to the trajectory of the ball, it will not lose speed, that acceleration causes a change in the direction of the velocity vector, not the norm (speed value). 

 

You will get a speed decrease if that acceleration has a component in the opposite direction of the velocity vector, and thats what PainGod was referring to with lift induced drag. You also get drag from the plane itself moving through the air (parasitic drag). Now in the case of a 109 and Yak making a max performance turn at high speed, I guess you could calculate how much drag of each type the planes have and compare them, but I dont know how to do it 

Edited by -=PHX=-SuperEtendard

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22 minutes ago, -=PHX=-SuperEtendard said:

 

As long as the force generating the turn is perpendicular to the trajectory of the ball, it will not lose speed, that acceleration causes a change in the direction of the velocity vector, not the norm (speed value). 

 

You will get a speed decrease if that acceleration has a compotent in the opposite direction of the velocity vector, and thats what PainGod was referring to with lift induced drag. You also get drag from the plane itself moving through the air (parasitic drag). Now in the case of a 109 and Yak making a max performance turn at high speed, I guess you could calculate how much drag of each type the planes have and compare them, but I dont know how to do it 

 

It's a matter of finding their respective drag coefficients. Once you have those, every other variable is easily sourced from historical documents or Wikipedia, and from there it's just two simple exponential functions.
However, finding those coefficients...yeah, well, good luck.

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On 7/13/2019 at 2:22 PM, E69_geramos109 said:

If the ball turns on an the void space with no air and with any kind of drag force the ball is going to lose some energy on the turn so it loses speed on the process and to keep the speed it need some kind of source power.

 

:huh:

No. 

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