Are slats shy ?

[TomcatViP]

Originally Posted by IvanK

To be pedantic slats are not speed dependant and work solely as a function of AOA though in 1g flight AOA and IAS are intrinsicly linked.
Not having the ball centred could easily result in different AOA on each wing and hence result in asymmetric slat deployment ... as can aileron input.

The Slat animation in CLOD at the moment is imo out of whack with what they should be doing. They should be coming out and staying out a lot earlier than they are at present. There is some discussion with the Devs on this going on using RAE test reports to come up with better more realistic operation. Not exactly sure when will actually see this.

The RAE data has 1G IAS (since they wernt recording AOA) slat deployment values for both the 109 and 110. These values can be used to extrapolate values for slat deployment at other G values. The essence being that AOA for slat deployment will always be the same, whilst IAS v G will change in a similar way to accelerated stall speeds v 1g stall speeds ie. Vstall X SQR G

Hi IvanK,

I hve been thinking at the solution you wrote over the night and I hve some doubt of the solution proposed: V_SlatOut = VstallxSQR(G)

At first I understand that this is similar to old IL2 and thus is a satisfactory solution for all. However my point here is that it cld be improved.

Slat deployment on the 109 was governed by the air pressure on the leading edge (LE) and the hinged mechanism weight and frictions forces.

a. Frictions forces are cte (K)
b. Weight effect is dependent on G (P=mg)
c. Dyn Pressue acting on the slat is a function of the speed of the plane (V) and the AoA (alpha) with Pdyn = 0.5roV²S*cos(alpha)

Hence we have V_SlatOut = f(G, Pdyn) + K

At 1G, the speed being known, as is the AoA we have the resulting value of the Weight and friction of the mechanism given that we make the calculation of the projected surface of the slat

We can now choose to consider the friction of the mechanism negligible given tht the slat were known to be retractable only by the application of one finger (and much attention were required to keep the slat close on the ground to protect the mechanism from ingesting dust, sand and small objects).

So basically we will hve V_SlatOut = f(G, Pdyn) tht result in the programmed law :

If V<= V_Stall*SQR(G) and If Pdyn>=mg (m being the resulting balancing mass calculated at the 1G condition) Then Slats Out.

The good thing is that by this way you hve an independent behaviour for both slat that can result in asymmetric deployment

Pls note tht the Weight I am talking abt is not really a mass per G. It's the seen mass by the system combining all efforts in the mechanism that result in the deployment of the slat minus the friction. I am pulling away the frictions forces as they are not dependent of the G and are basically negligible if the system is functioning optimally.

EDIT:

Sry Crumpp I did delete my post as I needed to check my info. Here it is right as before.

I checked the deployment principles here http://109lair.hobbyvista.com/index1024.htm

[David198502]

just a small vid i just made to spice this interesting thread up..

http://www.youtube.com/watch?v=cewk7t_gN-w