woodscra

My Feedback: (23)

Has anyone used one of these on a 33% plane? I have never seen one in action and wondered if they worked well or at all for large scale. They appear like they would provide a lot of throw, do they?

Thanks
Craig

cu. in.

I almost bought one of these at the LHS last week. I decided not to buy when I began to think of the geometry at the other end. For example, if the wheel was used on the rudder servo end, and the rudder was equipped with the typical pull-pull control horns (arms) like the Nelson brand, then there might be a problem with cable tension. If the rudder was equipped instead with another pull-pull wheel, then the wheel on the servo end would work OK.

The Nelson control horns/arms mounted on the rudder are really an offset bellcrank. This is why they work with a bellcrank on the servo end. In this case, there is a bellcrank-to-bellcrank connection.

The case of a wheel-to-wheel connection will work as well. Think of a chain on a bicycle.

However, mixing wheels with bellcranks is different geometry. It is not the best arrangement and will cause problems with cable tension because the wheel output at either end is linear at all angles, while the bellcrank output at the other end is not.

Of course, there are probably modelers who have gotten this mixed geometry arrangement to work well enough for their purposes. My point however is that it is not the best arrangement for maintaining constant cable tension and avoiding slack.

Anyhow, I thought that a wheel mounted on the rudder would look funny, so I didn't buy the servo end output wheel.

My $.02.

Bruce

woodscra

My Feedback: (23)

It would look a bit strange. Thanks for the input. I will think some on the geometry setup. I do want to prevent slack.
Craig

lynngordon

I used one of the H9 Pull/Pull wheels at first on my Sig Extra 300XS - however, it would continually come loose from one side - not track in the groove. That was with kevlar cables tight when centered, but full deflection either side would allow the cable to come out of the groove on the wheel. Went with a Dubro HD arm after two flights.

Lynn