gar springs

[Guest Erups]

It is possible to make a design which uses just one spring.For example you can use the same system used in a piston engine: the main axle of the yoke is connected to a lever turned 90

[Guest SHORT360]

Tuomas,The task is of course easier with a Cessna 152 where you have a mechanical trim wheel which can easely be linked behind the main panel to the rod of the yoke using your idea of a "dolly". I got the idea. Good one.But for my turbo prop which uses electric trim on the yoke based on a column it is a bit more tricky, thus the idea of the motor. I agree with you about the issue on using oil Damper without centering. It is only the half part of a good idea. In my mind as it seems to be in yours, the oil dampers are anly here to simulate the aerodynamic force on the controls. ( Or the simulated one via heavy hydro servos on airliners)You idea with the washing machine dampener is good also. I do use dampeners coming from fitness devices as you can see in one of my threads about rudder pedals made from fitness stepper.Cheers,Roger

[tigert 0]

>Tuomas,>>The task is of course easier with a Cessna 152 where you have>a mechanical trim wheel which can easely be linked behind the>main panel to the rod of the yoke using your idea of a>"dolly". I got the idea. Good one.>But for my turbo prop which uses electric trim on the yoke>based on a column it is a bit more tricky, thus the idea of>the motor. I agree with you about the issue on using oil>Damper without centering. It is only the half part of a good>idea. In my mind as it seems to be in yours, the oil dampers>are anly here to simulate the aerodynamic force on the>controls. ( Or the simulated one via heavy hydro servos on>airliners)>You idea with the washing machine dampener is good also. I do>use dampeners coming from fitness devices as you can see in>one of my threads about rudder pedals made from fitness>stepper.Yep. You could use a "power screwdriver" to turn the threaded rod. Just hook it to AC power instead of battery and re-wire the operation rocker switch to your yoke?It is not that easy on the Cessna either - we need a "worm gear" to turn the rotation 90 degrees and we need to transform it somehow to the rod. But hey, we have built it this far already, so I guess we'll figure it out :)//Tuomas

[tigert 0]

>It is possible to make a design which uses just one spring.>For example you can use the same system used in a piston>engine: the main axle of the yoke is connected to a lever>turned 90

[Guest Erups]

http://forums.avsim.net/user_files/90466.gifIn this image you can see an example:the yoke can be any form and assume any position (with respect to the spring raw force, that is necessary to keep it in the chosen center position; this means that in the above example the yoke itself is slightly bent to the left, the force the spring excerts needs to be high enough to sustain the forward pressure of the inclined yoke), the secret is in shifting the momentum from one direction to another, this is done using angled levers like i show in the example.The curved lever (curved just to make it visible) translates the spring axial force into a rotational force, that both dampens movement and centers the lever.Using various systems (gears, pulleys, whatever) this method can be adapted to every control, even roll and yaw.Hope i have cleared it :)

[Guest SHORT360]

Salve Claudio,It seems very interesting but sorry I have not understood how it can work. Is your view a side view or a front view. Could you "per favore" make a more detailled sketch.I spent nights and nights looking for a one gas spring solution and did never find it. CiaoRoger

[tigert 0]

>Salve Claudio,>>It seems very interesting but sorry I have not understood how>it can work. >Is your view a side view or a front view. >Could you "per favore" make a more detailled sketch.>I spent nights and nights looking for a one gas spring>solution and did never find it. >>Ciao>>RogerIt is a side view - my only concern though is that the yoke does not rotate that much, so it might be that the movement of the short lever might not be enough?Still, thanks for the pic, it is an interesting idea.Roger: The thick black part is the yoke column. Moving it back and forth will move the green dot up and down - but as it is pivoted from the bottom, it also moves the green dot along the "arc" when the yoke turns, thus moving it also a bit to the right, towards the gas spring.It might work, but I am concerned if the short movement is enough. It might though, I need to think a bit.. Thanks!//Tuomas

[Guest belairvideo]

Hi Rog,Does the "Stepper" centralise itself? Can it be adjusted?Great idea if it can. Any idea where I can get one - I am in U.K.?TONY.

[Guest SHORT360]

Tony,The "stepper" does not center itself. But I do use it so since 10 years and I never missed that feature, simply because in a real plane the rudder pedals are not centering either.I cant say where you may find it in the UK, but there must be a sport shop carrying it, for sure.cheers,Roger

[Guest Erups]

>It seems very interesting but sorry I have not understood how>it can work. >Is your view a side view or a front view. >Could you "per favore" make a more detailled sketch.>I spent nights and nights looking for a one gas spring>solution and did never find it. It is a side view, the yoke is the gray part (more a cloche then a yoke, but hey it's hand drawn ;)), the spring is in blue, with the rod in black. In green the joint between the spring rod and the yoke support lever.The theory is this: a spring excerpts an axial force in one direction only, the goal is to transform the direction and axle of movement of the control, in another kind of movement along the direction of travel of the spring.Furthermore you can study how the middle position of the control, can be the maximum extension of the spring, thus makeing the spring not only a damper but also a centering means.In my example this is accomplished this way:the yoke is pivoted at the base, the gray arc is fixed in position at an angle to the yoke, accomplishing two results: shifting the center of pressure along the spring axle, makeing it possible for the spring to push towards a center position; and transforming the movement along the spring axle.The second result you could have accomplished just by bolting the spring to the yoke, but this way you would need a counterforce to obtain the centering function.Shifting the center of pressure, you obtain both results.>It is a side view - my only concern though is that the yoke>does not rotate that much, so it might be that the movement of>the short lever might not be enough?Be enough for what?You can adjust the force by moving the spring body nearer or farther from the yoke, thus applying more or less pressure.I think it can be accomplished: if two small springs can pull up the read windshield of a car, one should be sure enough for just a yoke ;)

[Guest SHORT360]

Claudio,I get it. Nevertheless having made a quick attempt using the lot of gas spring I have at home I noticed that the "null zone" ( Yellow on the sketch) is very large and covers the range of the yoke travel, what results in a very poor dampingI guess that this is what Tuomas noticed.But may be did I miss one significant aspect in your design.GreetingRogerhttp://forums.avsim.net/user_files/90592.jpg

[Guest Erups]

It's plain geometry: in this case the smaller the "connection mean" between the yoke and the spring, the larger the unwanted movement (because you're working with the sinus of the arc, and the variation of the sinus near Pi/2 tends to zero).This because the smaller the connection the smaller the spring travel, thus the needed travel may even reside in the spring own backdraft or play.A workaround may be to make the connection longer, and use longer springs.Anyway i am just experimenting with you :) I just happend to think of this, you're my hands ;)Another option is to use two springs, both on the same side (thus reducing dimensions) anchored one slightly above and one slightly below the horizontal axle.Keep in mind this is similar to the system commonly used in commercial joysticks, and in that case you can clearly feel the play around the center position.The tighter the springs inside, the smaller the play zone.

[Guest SHORT360]

I did experiment with success the following design using two gas spring.IMHO the only weak point is a too strong centering which is not realistic.cheers,Rogerhttp://forums.avsim.net/user_files/90616.jpg

[Guest Stephan Haas]

edit: changed attachmentRoger,Thanks, from your picture and the others I got the idea.What I have been thinking of (triggered by this thread) is how to synchronise the FS-trim with the postion of the column trim. Let me explain this a little further.In real life in a given phase of flight I have to pull the yoke. It won't stay in its pulled position until I have the aircraft properly trimmed.{sidestep: in my younger years I did some glider flying and at least the R

[Guest SHORT360]

Stephan,Your idea is interesting. I only see one weak point: it is mechanically a bit complicated to get that "dolly" running smoothly. Here an other possible using your basic ideaYou can also put a a screw via a gear on each spring. The motor will get the screw sliding what will tied up the spring.See pictures below:http://forums.avsim.net/user_files/90792.jpg