Jedi lift, strapping servos to bottom skin

[Mikeb52]

I’ve just finished an install on my Jedi lift. Is it common practice to tie the wing servos to the bottom skin.  I know that wing ribs are incorporated in the wing moulding so is this necessary?

Mike B. 

[satinet]

I'm not sure it's common but it is done. If you do it then obviously you make it harder to get the servos out.

It's less necessary if the wing skin is stiff. I feel if you have servo frames That make it easy to get the servos out its a bit contradictory.

Vladamirs provide wedges i believe. 

[Mikeb52]

Thanks for your reply, and I agree with your comments. Just wondered what other flyers of Baudis models do? 

 

[Andy_B]

Ive not tied mine into the bottom skin on my Jedi 

[isoaritfirst]

If you fly often in big lift with loads of ballast and your model lasts a few years you may start to see bulges in the wing skins.

Adding another tie to the other skin may help.

But if you put that tie in with it exerting a pressure on the servo, that may result in the skins bulging.

Similarly with Servo mounts being flat and wing skins being slightly curved, gluing them in under pressure can result in flat wing skins.

 

 

[Mikeb52]

Thanks for your comments, all interesting views on this.I guess you have to be very careful with the install, with no undue pressure when you glue the frame ( with servo installed!! ) and if you tie it in with the bottom skin. 

[satinet]

The wing skin will flex and become softer over time. Especially if it's a fuxed linkage like lds.

I wouldnt bother if it's an f3f layup at this stage. 

[oipigface]

The main advantage of tying-in (I thought) was to improve the efficiency of the linkage. We tend to think of slop as arising from holes that are too big, or worn clevis threads, but a flexing top skin should be on the list as well. I usually tie in when I do my own install, but I can't remember having modified a factory install. Perhaps I should!

[satinet]

yes you're right. But like everything there's pros and cons. IF you take absolutely all the flex out of a linkage it puts more strain on the servo unless everything is perfect.  Also, as I say, it's harder to get the servo out from a practical point of view. Well not that hard to get it out but gluing the bridge back in can be difficult, because you need to remove some glue from under the wing skin. 

[Baldrick]

a modern digital wing servo can put out some serious force (6kg plus), it does seem reasonable to spread that load  between both wing skins.

I use fibreglass g10 sheet (off fleabay) or Plywood cut to fit under edges of servo bay aperture with 10mm or so extra ifor glueing.

If you are concerned about getting the servo out you can use UHU Por instead of epoxy (even that only takes a few seconds to remove with a Dremel).