Acroduster aileron control system

Discussion in 'Starduster' started by smizo, Feb 24, 2018.

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  1. Jun 13, 2018 #41

    EAABipe40FF

    EAABipe40FF

    EAABipe40FF

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    With due respect a blank canvas is fine in many applications but considering that the design of the AD2 aileron controls were done by experienced aircraft engineers and the result was several fatal accidents......I wonder if this is an area to be explored by the average homebuilder?

    OTOH the Starduster 2 design is well proven and can be adapted to the AD2.

    The only reason I can see for the reverser design is to get the pushrods under the floor although there may be more to it?

    To each his own but control systems is an area I personally might want to leave alone?

    I don't think having the push rods above the floor in the front pit of the AD2 is as big an issue as it is in an airplane where they are in the rear pit where the pilot has to climb over then on every entry/exit....or build something to protect them?

    Jack
     
  2. Jun 13, 2018 #42

    cwilliamrose

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    Something like the S-2 torque tube design might be one option. It would get the pushrods under the floor, put the torque tube on ball bearings (no plain bearings) and is certainly well proven. What else would have to change is where the real work comes in. All I was trying to say is that there are options out there that might be adaptable if the goal was to improve the design. Staying in the Starduster family for those options might be too limiting IMHO.
     
  3. Jun 13, 2018 #43

    EAABipe40FF

    EAABipe40FF

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    Bill,

    I don't disagree, only suggesting to be careful. I'm not familar with the S2 of coarse it's proven too.

    OTOH the original design with Kendall's modification would still be my way. If my new engine proves out and I keep the airplane I will go that route.

    Regards,

    Jack
     
  4. Jun 13, 2018 #44

    airplanegeek

    airplanegeek

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    Really will depend on your engineering skill level. If you feel like you can tackle a redesign then go for it. The type could benefit from your efforts. If this is something you’ve never done before, I wouldn’t recommend this be your first go at a major alteration. The system as designed will work fine for everyone except maybe Sean Tucker and Kirby Chambliss. Just substitute 4130 for the plans specified aluminum and you will have increased the durability of the system multiple times.

    Keep us posted !
     
  5. Jun 15, 2018 #45

    Larry Lyons

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    "Torque Rolls Prohibited" Love it, I may have to put one of those in Miss Smith with her rompin stompin 0-235! :p
     
  6. Jun 16, 2018 #46

    wfrandy

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    I am sure your right about it being plenty strong just substituting 4130 for the aluminum.

    That said, I am thinking of drawing up a linkage that eliminates the reversers and reverses the direction at the bellcrank in the wing instead. This would have the advantage of not having to redesign the control stick torque tube, which would allow keeping the pushrods under the floor.
     
  7. Jun 16, 2018 #47

    airplanegeek

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    Hmmm. Not following. The reverser is more then just a simple reverser. It set differential and it also serves as a bell crank.
     
  8. Jun 16, 2018 #48

    wfrandy

    wfrandy

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    What I have in mind is to reverse the direction at the aileron bellcrank in the wing. In order to get proper alignment I may still have to have a non-reversing idler in the current position of the reverser, which could have the diferential built in to it. If I can get the geometry right by totally eliminating it though, that would be better. I would then have to build the reverser differential into the aileron bellcrank in the wing. What I really dislike in the current design is the off-axis side load in the current reverser design, I would really like to eliminate that. Unfortunately, I do not have any wings yet, so I cannot visualize all the angles and paths in the real world. When I get time I will draw it all up in 3D cad and see what I can come up with though.
     
  9. Jun 16, 2018 #49

    cwilliamrose

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    Most airplanes I'm familiar with set (or eliminate) the differential travel at the bellcrank. Why would you want to do anything other than that? Is there an over-center condition created if you use the bellcrank only?
     
  10. Jun 16, 2018 #50

    wfrandy

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    The aileron differential is set at the bellcrank in the wing, in the same way as most others do it. Their would be no over center issues, other than the current ones that have occurred if positive stops are not used. In addition to the wing bellcrank, this system uses a reversing bellcrank, which appears to me to primarily serve to align the pushrod to pass through the wing without hitting any of the wing structure, while allowing all of the mechanism to be located under the cockpit floor. The differential built into the reverser bellcrank is in addition to that built into the bellcrank in the wing. I don't know if that differential can be recovered by changes to the wing bellcrank. At this point I don't see any reason why it couldn't be, but it is entirely possible that when I draw out all of the possible options, I may find that the best comprise is the one the original designer chose.
     
  11. Jun 16, 2018 #51

    cwilliamrose

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    In Solidworks I have found that every little angle in the aileron control system changes the deflections. A seemingly minor change is not without its effect. I used the bellcrank angle to dial in the deflections to zero differential but any design changes made requires another check to see the end result. The stock bellcrank angle is 75° and I'm now at 80.5° to get rid of the 2° differential of the S-1S and to account for the changes that happened going from Frise ailerons to symmetrical ailerons. I also have less dihedral and, and, and..................
     
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