Ad: This forum contains affiliate links to products on Amazon and eBay. More information in Terms and rules
And that's fair enough. At least when you read the report it gives some inkling of what was going on with the aircraft. To say that an airplane is "worn out" paints a very broad picture in determining why noted performance figures were attained.You can read the other reports on my site, too. I was not there the 1940s, I can't tell you if there was a strange humming noise coming out of the reduction gear- I can only read the reports written on the events, and I am sure they are already a concentrated, selected reflection on the reality..
Would the Mustang tested by the Soviets be one of the 10 Allison Mustangs received from the British?
Additionally I have often wondered about the intangible of stick forces at high speed as well as the slat effects and true change to CL at high AoA for the 109.. I'm agnostic regarding actual increased delta CL for the 109 or more contribution to stall retardation as AoA/Airspeed reaches critical points? One, Both? and how does one prove it?
FLYBOYJ said:What was worn and what was damaged???????????
Altea - I have never seen a 'full set' of full scale wind tunnel tests for any of these birds and certainly not for a fully functioning B/C/D Mustang with Radiator in operation generating potential thrust - and certainly not a full range of both Parasite drag and trim drag at various Reynolds Numbers and angles of attack.
If you go back and check the various threads, we have been down many a manueverability rathole and the required data to model these birds through a full range of asymmetrical, various altitude, different inital airspeed, for different flight regimes has not been available for good modelling.
Additionally I have often wondered about the intangible of stick forces at high speed as well as the slat effects and true change to CL at high AoA for the 109.. I'm agnostic regarding actual increased delta CL for the 109 or more contribution to stall retardation as AoA/Airspeed reaches critical points? One, Both? and how does one prove it?
The Bf 109F-2 captured and tested in Soviet-Russia was indeed in poor condition, whatever you claim on the contrary;
Just by luck, ....
. The experienced engineer noticed that the aircraft had undergone major repair at least four times and was completely worn out. .....
You mean all five of them, baught by russians ?The same holds true to the tested Bf 109E - I believe this one was sold to the Russians before the war,arriving in crates and they assembled it themselves - the engine seems to have some problem
There might be another explanation for this, the E-3 was just tested a "nominal" power, just as for soviet planes, not at "forced" one.This - lack of power output at low altitudes would explain why the Soviets measured such absymal turn times such as ~29 secs at 1000 m, whereas the German specs for the 109E was 18.92 secs for a sustained 360 degree turn at 0 m... and much more in line with the 18-19-20 secs measured on the F/G models.
I was not getting aggressive, please develop some thick skin, the only thing you have stated was vague information as you did on your original postI have made that clear a number of times on this forum before, but somehow people here forget very quickly. Also there is no need to get aggressive FLYBOYJ, I am merely telling it the way it is in a polite and controlled manner.
Anyway seeing as how Kurfurst already took care of this issue and don't feel the need to elaborate on what I wrote.
The engine wasn't performing well FLYBOYJ, and that will affect the turn rate nomatter the entrance speed.
Only if you're doing full power maneuvers - remember, Va will be at a lower power setting and airspeed and will determine your maximum maneuverability. As long as you're maintaining the required Va airspeeds you can and will determine the maximum performance parameter for the aircraft and again you're not going to operate the aircraft in Va at max power, and goes for any aircraft.FLYBOYJ,
Yes you can get enough speed to perform the maneuver, but that's the not the point, the point is the time in which you complete the maneuver. A 360 degree turn will take longer the more power you take away from the aircraft. Why ? Cause you'll be taking away thrust otherwise used to keep up the energy turn rate in the turn.
Shortround,
Lift drag are directly related. So the higher the lift, the higher the drag.
The Cl determines how much lift the wing produces, which in turn determines how much drag is produced as-well.
Mathematically it is explained like so:
(Cl^2) / (pi * AR * e) = Cdi [induced drag]
The Cdi makes up for around 95% of the total drag, so it's pretty significant.
What an a/c in essence is trying to do when executing a tight turn is reducing the forward speed of the original path you started out traveling towards, whilst at the same time speeding you in another direction. In other words the wings are acting kinda like giant airbrakes, and so the larger a surface area you can present towards the direction your going (i.e. the higher the AoA you can pull), the faster you're going to loose progression speed in that direction whilst adding speed to a new one. And what the slats allow you to do is just that: to present a larger surface area in the direction your a/c is going without it stalling out.
Soren - I'll try to sum up responses in this one post.
First - you are right about 1.70 being posted by you as a Max CL for fully deployed slats for the 109
What I was getting to is that in the crafting of a sophisticated model of a 109 in a turn you need a.) a Polar Drag set of data specific to the 109, b.) you need the airspeed/AoA data for deployment of slats - and c.) as Altea says a *reliable* set of Hp curves for the altitudes you wish to model.
CD0 is an interesting drag datum but it is solely related to the Wing in question.
Parasite Drag is a function of everything other than Induced Drag (Form drag, Friction Drag, etc) and, as you can see from the attached Drag Polar, it varies non linearly with velocity. The values are extrapolated from various charts in Preliminary design but only 'finalized' in flight tests and wind tunnel tests.
Induced Drag is as you note above and pretty accurately calculated with the equation you posted.
Back to CD0 - it is good for one angle of attack and represents the minimum drag of the airfoil, but equally it is Always at a very low angle of attack for the airfoil in question and not very useful in high AoA profiles that would be needed in turning manuevers.
As to stick forces - I only know what I believe to be true from other pilots that flew the 109 but the 51, while not as 'friendly' at high speed as a boosted P-38L, is easily a one hand capable stick. The rudder was tougher at high speeds but the reason the reverse boost rudder modification was made to the Mustang was to stiffen it up at high speeds to discourage yanking the tail off while turning in a high speed diving chase - the elevator stiffened up but not to point where two hands were required.
Admittedly I never came close to maxing out any manuever in the Mustang but I was both in the 400 mph range and 5+ G turn range so I have a sense of the control forces and can say they aren't near as bad as you seem to imply.
Anyway I found a good representation of a typical Drag Polar to help explain my point
I think I am missing something here so I would ask that somebody please point it out to me.
As I understand it ( and I am not an engineer or pilot) any wing increases it's lift coefficient as it's angle of attack increases.
As the angle of attack increases the drag coeffecient of the wing changes.
Slats/slots change the airflow over the wing and prevent stalling at high angles of attack.
Slats/slots do little or nothing to improve coeffecient of lift until an angle of attack just below stall is reached.
Increasing the angle of attack further means the unslatted/slotted wing stalls and the coeffecient of lift drops.
On the slatted wing the angle of attack can be increased a number of degrees more, thereby increasing lift, before stall occurs.
But hasn't the drag been going up as well? The wing at these higher angles of attack ( over 13-15^) having an even higher coeffecient of drag than it did at 10-12^ angle of attack?
If this has been gone over before or if I missed it, my appoligies, but could someone point it out to me.
Bill,
As for the control forces of both a/c, I agree with you, and I wasn't trying to make the P-51 sound bad, I was just pointing out that elevator forces are mentioned to be similar in that a/c compared to the 109 at high speeds. In short the same is said about the 109, modern pilots mentioning that 5+ G maneuvers are quite easily achieved with one hand on the stick at moderately high speeds. Exceeding 700 km/h and the 109's elevators becom very stiff however, but two hands on the stick will solve that according the pilots. Above 750 km/h and it becomes very hard even with two hands and trimming is needed.