On Friday, April 26, 2019 at 7:02:56 AM UTC-6, ProfJ wrote:
Hi Folks,

Looking for some crowd wisdom (or individual wisdom) on the subject of putting seals on a previously unsealed glider. I have an SZD-45 Ogar motorglider, which is a lot of fun to fly except for a couple of things. The main one is that the stick control forces get really high as the speed goes up (as in, two hands on the stick at 70kt). This is not a mechanical malfunction, but needs some explanation. The aileron mechanism is not the usual bellcranks and linkages, but a peculiar combination of a sliding connection between the wing pushrod and a linkage to a 45-degree angled bolt on the aileron. I do not know what this mechanism is called, but apparently is was common on 1970's gliders because it is entirely enclosed in the wing profile. I can see why it fell out of fashion though. The previous owner of my glider, who is an excellent mechanical engineer, spent considerable time and effort trying to make this smoother (such as replacing nylon sliding contacts with teflon, etc) but it's pretty clear that the mechanism is just not designed for low control forces.

I was considering fitting aileron seals, both to reduce drag and also because there is some anecdotal evidence that this reduces stick forces. Is there any reason not to try this? The glider is experimental category - I was thinking that I might ultimately throw out these ****ty linkages and fit a bellcrank system, but that is major surgery, would prefer to try less invasive stuff first.

Thanks,
Jon

Jon,

I do not think that the type of aileron seals used on sailplane will reduce aileron friction where high unsealed forces due to mechanical linkages are already present. It may add to it. It may reduce drag though.

Mike