Quote:
Originally Posted by VO101_MMaister
You are amazing guys... How the hell did you end up on the spit`s high speed stall characteristic in a thread about the leading edge slats of the 109?????
There are no spinproof airplanes, there ones which are hard to put in a spin. The wing is stalled when the airflow become turbulent over the whole upper wing area and so it looses its lifting effect. The slats ensure a laminar flow over the outer wing around the ailerons at low speed so you have some more control before the wing stall. No magic here. It can postpone the stall but it won`t eliminate it.
The spin is when only one of the wing is stalled due to the assyimetrical flow. The slats could open independently, so they could prevent a spin by opening only on the wing which was just about the stall. But again it was only postponing the spin in this case and gave you more control.
On the other hand the slats could make a fuss, when only one of them opened due to some mechanical failure, and it resulted an assymetrical lift and so an unpredicted spin at low speed. Also they raised the drag when they were open, what meant quicker de-accceleration.
I have never flown an aircraft with slats, so no practical experience here, but as I understand Crumpp did, and he gave a quite good description about the acting of such an airplane.
I also feel that the 109 in the game is a bit sensitive, but hey, I can`t tell if it is right or not. Can you? I have never flown one, and I have never read a review of the current flight modell by a real life 109 jockey. Have you? There are quantitive specs what can be measured and checked in numbers and graphs. And then there are the sensations. It is quite hard to translate a pilot`s story into an accurate flight model. In these stories you can only get what that particular guy felt in that particular situation, and then how he can recall it after maybe 60-70 years. Well it is not bomb proof for sure. Now translate it into a computer game for guys who are flying in an office chair, and they pull as hard as they want without feeling the punishment of the real G-forces or the physical exhausting of an aerial battle. So we can have a depute on it for 1000 years and we never gonna agree.
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Good post. Your right, the thread is getting off track and needs to get back on.
The behaviors of the Bf-109 are fairly well documented and we have some measured data. There is enough there to construct a reasonable facimile. Unfortunately the RAE did not have a standard or the measuring equipment developed by the NACA until later.
Also other reports and the Operating Notes give some really good clues about the stability and control of the Bf-109. For example, the Bf-109 (in a trimmed condition) was limited by design to about 5G's. This keeps the pilot safe and allows maximum attainable manuverability with gusting. You can see this in the turn performance evaluation by the RLM/Mtt of the Bf-109E.
5600/140 = 40 lbs MINIMUM control force required on the elevator at 1G and we require a stick force per G greater than 8lbs/g.
I would think CloD FM is sophisticated enough to use sections. If that is the case, simulating the slats effect on stall behaviors should be a matter of doing exactly what the designers did.
Adjust the coefficient of moment of the elevator accordingly with the outboard wing sections and stalled main portion wing sections.
At the forward CG point where our elevator requires the most moment, the airplane should not spin. As the CG moves rearward, the ability to enter a spin is increased until at its most rearward position a spin entry is possible with deliberate effort.
Reading the synopsis of the Mtt spin trials the Bf-109 at rearward CG reminds me of a C-172 spin qualities at the Cessna forward CG. You must enter a power on stall and give a vigorous rudder input to the direction you want to spin. The break is crisp as the rudder feel is noticeably sloppy near the break but solid until that vicinity. The airplanes settles into more of a corkscrewing dive than a developed spin. The PARE can be pretty sloppy in a 172, letting go of the controls will effect recovery many times. Reducing power and stepping on the high wing results in immediate recovery. You can just about ignore the A and E in PARE in a C172 as long as they are not extreme.