That must have been one weak pilot Juha to complain about heaviness at 350 km/h, but his explanation certainly explains why he didn't do any better. German pilots mention that it was possible to achieve full elevator deflection at speeds of even 750 km/h, with a firm two hands. Above 450 km/h German pilots noted that elevators started to become heavy, but they got used to it.
On Soviet turning time tests. Comments Please (1 Viewer)
- Thread starter Juha
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- #104
Odd then, maybe he was just having a bad day of cramps ? 
No seriously, there can be many reasons for such a thing, the state of the a/c, the strength of the pilot, heck the size of the pilot even. He was probably used to the light controls of a Buffalo and therefore needed some time to adjust to the 109. And it indeed did take time to adjust from one a/c to the other.
Mark Hanna:
"When you maneuver above 500km/h, two hands are required for a more aggressive performance. Either that or get on the trimmer to help. Despite this heavying up, it is still quite easy to get 5G at these speeds."
At 5 G's most pilots will black out btw.
No seriously, there can be many reasons for such a thing, the state of the a/c, the strength of the pilot, heck the size of the pilot even. He was probably used to the light controls of a Buffalo and therefore needed some time to adjust to the 109. And it indeed did take time to adjust from one a/c to the other.
Mark Hanna:
"When you maneuver above 500km/h, two hands are required for a more aggressive performance. Either that or get on the trimmer to help. Despite this heavying up, it is still quite easy to get 5G at these speeds."
At 5 G's most pilots will black out btw.
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Soren
he had been a test pilot ca 1½ year at the time of the 109 tests and had flew all kinds of planes at that time incl medium bombers. And he flew several 109s during the tests to get used the a/c etc. But yes, stick forces were much higher in 109G, 8-9kp/G, so exceptionally high, ca. as big as in Blenheim Mk I. In Brewster 239 they were ca 3kp/G, in Morane MS 406 2kp/G.
Juha
he had been a test pilot ca 1½ year at the time of the 109 tests and had flew all kinds of planes at that time incl medium bombers. And he flew several 109s during the tests to get used the a/c etc. But yes, stick forces were much higher in 109G, 8-9kp/G, so exceptionally high, ca. as big as in Blenheim Mk I. In Brewster 239 they were ca 3kp/G, in Morane MS 406 2kp/G.
Juha
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claidemore
Senior Airman
RAE test pilots said it was almost impossible to pull the 109 into a hard enough turn to black out, due to the heavy stick forces required.
Basically, even though it might be shown on paper that the 109 could pull +7G, in real life it would not happen, the pilot would not be able to apply enough stick force.
The limititng factor is not aerodynamics, it's mechanical advantage, or lack of it in this case.
As Soren mentioned in another thread, if the 109 had had a different control system, it would have been a much more dangerous opponent.
Basically, even though it might be shown on paper that the 109 could pull +7G, in real life it would not happen, the pilot would not be able to apply enough stick force.
The limititng factor is not aerodynamics, it's mechanical advantage, or lack of it in this case.
As Soren mentioned in another thread, if the 109 had had a different control system, it would have been a much more dangerous opponent.
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Hello Claidemore
as i wrote on your 109 thread, the heaviness of control forces of 109 at high speeds might well has been deliberate to protect structures for overloading and so failure. 190 was more sturdy built than 109. Breaking up or more sturdy built but heavier Bf 109 might well have been less dangerous opponent. There are often trade offs in a/c design.
Juha
as i wrote on your 109 thread, the heaviness of control forces of 109 at high speeds might well has been deliberate to protect structures for overloading and so failure. 190 was more sturdy built than 109. Breaking up or more sturdy built but heavier Bf 109 might well have been less dangerous opponent. There are often trade offs in a/c design.
Juha
drgondog
Major
Gent's - you both know Cd0 is also a function of Reynolds Number? which in turn varies with airspeed, selected reference dimension (such as mean wing chord, or stream tube diameter, etc) and density?
Any published Cd0 from a wind tunnel test should also reference the Reynolds number as well as the scale of the model tested. The Lednicer paper is a specific example. In Mike Williams site, the performance comparison test report on the He 162 and Me 262 are specific examples in which parasite drag is referenced to specific velocities.
You CAN Calculate Cd0 when you have a specific and unique set of conditions such as max level speed for a specific power setting and altitude. How are you two going to calculate the Cd0 variances as the aircraft of interest enters the turn then proceeds to a max turn rate at a much lower velocity? How are you going to introduce Trim Drag into the parasite drag equation? It is relatively small in level flight but more significant in max turn/high AoA?
Soren, how do you validate ClMax in a max turn for the 109, and/or prove (not postulate) that the Clmax in the max turn at max AoA is the same as the Clmax for level flight stall?
Last but not least the Clmax of the system (wing body) may be calculated for a model in which the airframe is demonstration a sustained turn, maintaining level flight, but remember that the entire wing/body system (propeller, fuselage, wing, tail, etc) all contribute to both the total lift and drag of the system. The fuselage and tail contribution can be assumed negligible in level flight but becomes more interesting as the wings incline more to the vertical in a steeply banked turn.
What would be more interesting is to present the models you posed to each other above - and derive the turn rate/bank angle - which should agree closely with the flight test results
Assuming the model is correct to the physics....
Any published Cd0 from a wind tunnel test should also reference the Reynolds number as well as the scale of the model tested. The Lednicer paper is a specific example. In Mike Williams site, the performance comparison test report on the He 162 and Me 262 are specific examples in which parasite drag is referenced to specific velocities.
You CAN Calculate Cd0 when you have a specific and unique set of conditions such as max level speed for a specific power setting and altitude. How are you two going to calculate the Cd0 variances as the aircraft of interest enters the turn then proceeds to a max turn rate at a much lower velocity? How are you going to introduce Trim Drag into the parasite drag equation? It is relatively small in level flight but more significant in max turn/high AoA?
Soren, how do you validate ClMax in a max turn for the 109, and/or prove (not postulate) that the Clmax in the max turn at max AoA is the same as the Clmax for level flight stall?
Last but not least the Clmax of the system (wing body) may be calculated for a model in which the airframe is demonstration a sustained turn, maintaining level flight, but remember that the entire wing/body system (propeller, fuselage, wing, tail, etc) all contribute to both the total lift and drag of the system. The fuselage and tail contribution can be assumed negligible in level flight but becomes more interesting as the wings incline more to the vertical in a steeply banked turn.
What would be more interesting is to present the models you posed to each other above - and derive the turn rate/bank angle - which should agree closely with the flight test results
Assuming the model is correct to the physics....
VG-33. Please keep it civil and not make it personal with insults which are not necessary. This is your first and final warning.
Bill,
Regarding the Clmax, the only thing which really could change this even slightly would be aeroelasticity, but I highly doubt it had even a 1% effect on the Clmax, esp. on a slatted wing.
Having the Clmax of both a/c in clean configuration gives us a pretty perfect idea of how well each a/c turns at speed.
As for the Cd0 figures, the 109's is derived from full scale tests of a production a/c.
Not the case Claidemore. The normal pilot could pull full elevator deflection in the Bf-109 even at 750 km/h, but it required two hands on the stick. (Normally you just have one hand on the stick, the other controls the throttle etc etc..) So the pilot was indeed capable of pulling the Bf-109 into a quick 7 G turn if he really wished to do so, and many did, however it wasn't as fingertip easy an affair as in an a/c like the Spitfire.
The main improvement would be on roll rate at high speeds Claidemore, that's what I was getting at, cause the 109 really lacked this. A full performance turn could be initiated at any speed up until the max permissable dive speed IF two hands were used, bu roll rate was another issue.
Regarding the Clmax, the only thing which really could change this even slightly would be aeroelasticity, but I highly doubt it had even a 1% effect on the Clmax, esp. on a slatted wing.
Having the Clmax of both a/c in clean configuration gives us a pretty perfect idea of how well each a/c turns at speed.
As for the Cd0 figures, the 109's is derived from full scale tests of a production a/c.
Not the case Claidemore. The normal pilot could pull full elevator deflection in the Bf-109 even at 750 km/h, but it required two hands on the stick. (Normally you just have one hand on the stick, the other controls the throttle etc etc..) So the pilot was indeed capable of pulling the Bf-109 into a quick 7 G turn if he really wished to do so, and many did, however it wasn't as fingertip easy an affair as in an a/c like the Spitfire.
The main improvement would be on roll rate at high speeds Claidemore, that's what I was getting at, cause the 109 really lacked this. A full performance turn could be initiated at any speed up until the max permissable dive speed IF two hands were used, bu roll rate was another issue.
drgondog
Major
As I understand the 109 was stiff in both roll and turn at high speeds in comparison to P-51, Boosted P-38J-25 and above and Spitfire.
claidemore
Senior Airman
I agree with you 100%
BTW, Kurfurst just posted on another thread that the 109 did indeed have push rods for the ailerons.
Learn something every day on these forums!
Hello drgong
Thank you for your explanation. I think it will be hard to explain that to someone like soren since he even doesn't know that AoA for the Clmax is not the same than AoA for the best ToT Clman.
So from theoretical german data (Kurfurst site) for the 109E, On paper::
T : 18.92s
R: 203m
Vturn = 67.4 m/s
Gturn = 2.49 g
Cl man = 2 mg G/ rho*S* V^2 = 2*2450*9.81*2;49 / 1.225*16.2*67.41^2 = 1.33
As every one can see it's very different from Soren's Cl = 1.7 value.
And now from soviet real 109E-3 trials, In the real life::
V: 250 km/h* (* instrumental value, i suppose: real speed ~ 260-270 km/h)
T: 27.5
Vturn = 72.2 m/s
R = 315
Gt = 1.96
Cl man= 2 * 2600* 9.81* 1,96/ 1.114* 16.2 * 72.2^2 = 1.07
That means Cl max ~ 1.07 / (0,8…0.85) = 1.35
So it's close to british values for the Emil quoting Cl max = 1.4 max at a higher Re number.
Regards
VG
PS
I accept all remarks, with pleasure.
Thank you for your explanation. I think it will be hard to explain that to someone like soren since he even doesn't know that AoA for the Clmax is not the same than AoA for the best ToT Clman.
So from theoretical german data (Kurfurst site) for the 109E, On paper::
T : 18.92s
R: 203m
Vturn = 67.4 m/s
Gturn = 2.49 g
Cl man = 2 mg G/ rho*S* V^2 = 2*2450*9.81*2;49 / 1.225*16.2*67.41^2 = 1.33
As every one can see it's very different from Soren's Cl = 1.7 value.
And now from soviet real 109E-3 trials, In the real life::
V: 250 km/h* (* instrumental value, i suppose: real speed ~ 260-270 km/h)
T: 27.5
Vturn = 72.2 m/s
R = 315
Gt = 1.96
Cl man= 2 * 2600* 9.81* 1,96/ 1.114* 16.2 * 72.2^2 = 1.07
That means Cl max ~ 1.07 / (0,8…0.85) = 1.35
So it's close to british values for the Emil quoting Cl max = 1.4 max at a higher Re number.
Regards
VG
PS
I accept all remarks, with pleasure.
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Bill the Clmax figure is derived directly from the full scale aircraft itself, so I really don't understand what it is you're getting at here ?
Prop thrust will only heighten the lift over the covered area as it will be moving faster over that portion. And the Clmax will increase with increases in AR. And the 109 featured both higher thrust a higher AR wing.
drgondog said:
Cd0 is simply the drag coefficient at zero lift, that's all. To get the Cd we need to add the Cdi, which everything esle being equal is highest with the a/c wih the higest Clmax, the 109 in this case. However this is where the 109's small size comes in to help, as with every coefficient it needs to be multiplied with a real size figure.
VG-33 said:
Oh give me a break VG-33, you're the one who's in deep water my friend, not me. It's amazing you can't even see that yet
A max performance turn is carried out at or close to the Clmax of the a/c at full power to achieve the smallest turn radius and highest turn rate. You're now trying to deny that VG-33, again demonstrating that you know nothing of what you're talking about and further ridiculing yourself.
And again your simple little calculations based on the flight tests don't prove squat.
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Regarding the Soviet Finnish tests. It is possible and highly likely that the high stick forces had a negative influence on these, esp. if one hand was used, which I believe is almost guaranteed.
The Bf-109 needed two hands for aggressive maneuvering at above 500 km/h, but with this full performance turns could also be made. That two hands were needed however was a disadvantage to some degree, that I can agree with.
The Bf-109 needed two hands for aggressive maneuvering at above 500 km/h, but with this full performance turns could also be made. That two hands were needed however was a disadvantage to some degree, that I can agree with.
A break, what for? Since your'e such a big scientist you will prove with no efforts thant j'm wrong.Oh give me a break VG-33, you're the one who's in deep water my friend, not me. It's amazing you can't even see that yet
What do you mean by close to or at Clmax?
VG - 33
FLYBOYJ
"THE GREAT GAZOO"
"A disadvantage to some degree?" Sorry but if you need two hands to fly an aircraft, you're loosing the ability to effectively bank and thus complete coordinated turns. This was a problem in the MiG-15 and 21and is a MAJOR disadvantage.
