Hi guys

Can you help.

I am trying to operate the ailerons and elevator halves with hidden push rods.

It will be in a 1/4 scale jet so I have enough thickness in the section for the servos, but it is the slop free actuation that worries me.

any ideas or web sites would be appreciated. The full size has very small, less than ideal options for external actuation, hence my attempt to drive the surfaces internally

Thanks Ian

ps the wing and tail are foam veneer

saw these in the David Platt videos on building his hunter. They are called swingees and maybe what you are looking for.

http://www.unitracts.co.uk/index.htm...erProducts.htm

not a very good pic to explain their operation but they do allow for a totally enclosed linkage. try searching swingee you might find more examples.

regards John

I/ve never used these, but the concept seems sound.

Just note that slop will be magnified greatly with this system, so equivalent "workmanship" will produce much more slop with this system.

http://www.irfmachineworks.com/rds/

PS I have seen "swingees" on 2 jets now and they were both very sloppy. Maybe they were put in wrong, but one was on Viper ailerons, the plane having been built by the best builder I have ever known

The ones on this site are called Beckman actuators, look like the swingee in principle and claim to be slop free

http://www.hobby-lobby.com/balllink.htm

Ian

Just realised how close you are to where I live, just down the road 30 miles or so. so if you want to borrow the David Platt video let me know and we could meet up. Do you fly at Long Marston?


Regards John

Eddie Weeks was working on something that he thought would work, but I think it fell into oblivion when other modelers suggested it wasn't worth the effort? It was about 8 to 12 months ago here in the jets forum.

Sean

I'm using the RADS system that Mr. Matt linked to. Works great so far on a .40 sized sport plane. I may use a beefed up version on a turbine in the future.

Marc

Ian,
In the last 35 years I have tried most of these systems and they all suffer from slop. At model sizes we are always going to have to compromise to get a geometry that will work.
Torque tubes can be made to work to a degree, but need to be engineered extremely well.
You cannot beat a direct short linkage. I would apply the KISS principle personally.
What is the model of BTW?
Regards,

Thanks for the replies guys


Mr Matt
I remember seeing ads for the swingees, but was always a little concerned about the lack of moment arm that may enlarge the play even with the best designed linkage and quality servo.

Marc
I searched on the scale forum and found the rads and wondered if any one had used them for jets.

Hi Fellow Brits John and Johnmac
We live a little further apart than you think, I am on the Somerset / Dorset border, I have a couple of that Platt series of videos 3 and 5 , I think someone in my club (Sedgemoor) has the others so I will borrow from him, thanks for the offer.
Yes I firmly agree the KISS principle, but I was trying to avoid the normal servo arm (even faired in) pushrod to an external horn. As I said in the original post the full size does not have any suitable external rods like this even to remotely disguise our normal set-ups.

But once again thanks for all the inputs guys

Ian

Should have checked the spelling [8D] thought it was Sherbourne in Warwickshire.

On Video 1 Dave Platt in his usual style goes into great detail in the use of the device, especially its advantages in swept surfaces.

Later he describes the fitting in detail. He use them on all control surfaces.

Well worth a look


John