Wanted: Expereienced Flight Aerodynamicists for Winch Launch Investigation

I looked a little more into x-plane

The X-plugin data interface data items are listed at.
http://www.xsquawkbox.net/xpsdk/docs/DataRefs.html

search for fside_plug_acf
Appears to be 6 data items for extra plugin provided 3d force and 3d moment.

The simulator also include a builtin winch launch system.
Not sure what the model for the winch power curve is, but the parameters controlling it appear to be at /sim/world/winch in the same file.

On Sunday, October 6, 2019 at 7:30:51 AM UTC-7, wrote:
I looked a little more into x-plane

The X-plugin data interface data items are listed at.
http://www.xsquawkbox.net/xpsdk/docs/DataRefs.html

search for fside_plug_acf
Appears to be 6 data items for extra plugin provided 3d force and 3d moment.

On Sunday, October 6, 2019 at 12:16:43 PM UTC-7, G Moore wrote:
On Sunday, October 6, 2019 at 7:30:51 AM UTC-7, wrote:
I looked a little more into x-plane

The X-plugin data interface data items are listed at.
http://www.xsquawkbox.net/xpsdk/docs/DataRefs.html

search for fside_plug_acf
Appears to be 6 data items for extra plugin provided 3d force and 3d moment.

The simulator also include a builtin winch launch system.
Not sure what the model for the winch power curve is, but the parameters controlling it appear to be at /sim/world/winch in the same file.

Stu857xx,

Thanks for looking into X-Plane a bit more. The primary motivation for this investigation is to help in determining the tension servo control law characteristics and does it need to change for different phases of the launch.. For that, I need a simple representative model that will capture the glider's aerodynamics effects on the mass-spring-mass system. A suitable pitch model can be linearized for the various phases of the launch for this servo system analysis. The X-Plane model is overkill for the problem to be analyzed. Regardless, I would need a skilled flight dynamicist to determine what elements in the X-Plane simulator are needed and which could be eliminated for the simple model so that brings me back to my original need for a flight dynamicist.

A secondary purpose for this model would be for full launch simulations that will eventually include the full active tension servo system. One place where the X-Plane simulation engine might be very valuable is as a check on the simple model's validity. If full launch simulations were done with both the simplified model and the more sophisticated X-Plane model and there were significant differences in observed behaviors, that could signify there are issues with the simple model, i.e., it is too simple and not representing the behaviors of interest. Again, having someone with experience with such models and simulations would be a tremendous asset.

-George

Stu857,

I read further on X-Plane and learned that its models employ what is termed Blade Element Theory, a theory originally developed in 1879 to study the behavior of propellers, by breaking up the propeller blade into multiple small parts and integrating their effects (according to Wikipedia). This goes to your earlier comments about the simulator building a model based on "the plane's shape and calculates the aerodynamic forces on the fly." I believe such a model that integrates the effects of all the glider's shapes would be very difficult for anyone, even a skilled flight dynamicist, to convert to the kind of model that I need for these control system analyses. I am hoping that a simple pair of coupled systems with the glider's mass and angular inertia comprising the energy storage elements will suffice for my needs. (This goes to the classic short period and phugoid modes of simple pitch axis aircraft models.)

-George

George,

I don't see him on RAS anymore, but you might check with Bill Daniels. He has been promoting automated winches for many years and may have details to share.

I'd check the SSA member locator for his contact information.

Mike B.

On Monday, October 7, 2019 at 11:26:36 AM UTC-7, SoaringXCellence wrote:
George,

I don't see him on RAS anymore, but you might check with Bill Daniels. He has been promoting automated winches for many years and may have details to share.

I'd check the SSA member locator for his contact information.

Mike B.

Mike,

Thanks. I have worked with Bill for over 15 years on advanced winching. I originated many of the winch tension control, semi-automation, and battery-electric drive concepts employed in his designs. I have discussed the need for this model with him previously and he does not have the needed skills for this analysis. I have been active in the WinchDesign and WinchEngineer winching forums and have made similar solicitations for help there over the years with no success. I decided to try RAS to expand the audience that might contain, or help identify, someone with the right skills that would be interested in this problem. Again, if anyone would read the problem statement at the beginning of this thread and might know of someone that would be a good fit for this problem I would greatly appreciate their forwarding the solicitation to them for their review.

-George

If you need a plan B. Instrument the cable with a tension logger. Instrument the winch with throttle position indicator, cable angle & Drum RPM. Take it to a winch clinic. Compare the graphs of the instructor's demo's with the students flights. In my opinion you could do it with speed control, cable angle, ramp rates, and tension limiter overrides. All the winch driver has is the throttle, his process seems pretty repeatable from launch to launch once he gets dialed in on speed. The students actions will be all over the place. Reliable control based on glider pitch angle, and Launch phase combined with the lag in the system with possible signal loss might be a tough go when the pilot does something stupid or the coms break down. These days you can't neglect the inherent liability of designing a fool proof system that encounters a master level fool with a competent lawyer. Good luck, this is interesting stuff, sorry I can't help with the math.

SF

On Monday, October 7, 2019 at 5:26:40 PM UTC-7, SF wrote:
If you need a plan B. Instrument the cable with a tension logger. Instrument the winch with throttle position indicator, cable angle & Drum RPM. Take it to a winch clinic. Compare the graphs of the instructor's demo's with the students flights. In my opinion you could do it with speed control, cable angle, ramp rates, and tension limiter overrides. All the winch driver has is the throttle, his process seems pretty repeatable from launch to launch once he gets dialed in on speed. The students actions will be all over the place. Reliable control based on glider pitch angle, and Launch phase combined with the lag in the system with possible signal loss might be a tough go when the pilot does something stupid or the coms break down. These days you can't neglect the inherent liability of designing a fool proof system that encounters a master level fool with a competent lawyer. Good luck, this is interesting stuff, sorry I can't help with the math.

SF

SF,

We have inline instrumentation pods with tension sensing, GPS tracking, and accelerometers. We also have instrumentation packages for monitoring the winch during the launch. We have logged a number of launches on several classic winches. Those logs have validated many of our theoretical models for winch launching. In particular, they show the oscillatory behavior predicted by the mass-spring-mass model during the ground roll and early rotation. But during the climb, the observed behaviors are not so clear. That is why we are looking for a flight dynamicist to help us improve that model to include aerodynamic effects. Knowing how/if the aerodynamics affect this mass-spring-mass oscillatory system will greatly simplify the design of the control law for the tension servo system on our prototype.

-George