RDS vs. servocity?

[fprintf]

What mades the RDS system work? Is it just the connector that allows you to attach a rod onto the end of a servo output shaft?

RDS is found at http://www.irfmachineworks.com/rds/

and yet I have also found the following at servocity http://www.servocity.com/html/servo_shaft_adaptors.html, although they look kindof big for thin glider wings.

I think it is kindof neat that the rotary method of actuating ailerons seems to be catching on. I haven't tried it yet, and since I am cheap will be looking for the Drela method of using tubing to connect the servo and associated rod.

[wjjones]

I think the main benefit of the RDS system is that it provides a hidden method for moving a control surface. Because the servo and control rod are within the wing, nothing portrudes as with most pushrods.

It works by rotating that long rod, which in turn leverages the shorter bend within the slot in at plywood box, which is mounted in the control surface.
I don't know if it's more effective than pushrods, but I'm sure someone who knows more than me can give an opinion on that.

But....I read an article on it, then saw a club member describe how it is done and it's a MAJOR PITA if you ask me. It took a long time to install, and it looks like another PITA if you have to do maintenance or repairs.

I still think the concept is neat, but for me the hassle factor weighs heavily in what I build.

[seanpcola]

Just finished installing this set-up in a very large scale Jantar for rudder and elevator. The benefits are not only buried linkage but a multiplication of available torque from the servo. The first time installing it was problematic but once you catch on to all the details it is great! I will try to post some photos soon but will be tied up for a few days. For more info go to Harley Michaelis' website. Don't have the link in front of me but if you can't find it let me know and I'll post that too.

[fprintf]

http://genie.rchomepage.com if I recall. It is on one of the "files" and explains pretty well how to do it. Dr. Drela is now calling for it on his Supra plans.

[KevinSheen]

fprintf,

Harley Michaelis designed an internally actuated system which he called RADS in the 70's or 80's that were published on a number of his designs. RDS is an evolution, if you will, of his RADS design. I think Kimbrough Products was the first company to produce RDS couplers in quantity for Harley. Walt Dimick produced the machined aluminum tops and tempered torque rods later to help the 'ARF only' crowd. I'm kind of kidding with that last comment. I've purchased Walt's stuff and it works well.

It looks like Servo City jumped on the band wagon and in order to avoid any infringement, they made the product different and call it something else but it is essentially RDS.

Dr. Drela has also seen the benefits of using a rotary actuated, all internal control mechanism and started with them on his Super Gee and again on his Supra. His are different still, using the original control horn and essentially manufacturing all of the bits but ending up with the same, rotory actuated, completely internal flap and aileron control.

I've used it on two planes that I've built (both Michaelis designs). Major PITA isn't what I think of when I think back on the installation but I will admit that it was different the first time. The second was actually fairly straightforward. I have yet to experience ANY additional maintenance headaches because of it. One MAJOR plus, having both wings that are clean (RDS) and wings that aren't (the OLD way), is that the wings without all of the 'stuff' hanging out of them, are easier to handle, store and transport etc. The clean aerodynamic aspect makes sense but not being an engineering type, I can't tell you one way or another about that.

So you're asking about RDS now, does that mean you're building a Supra, GENIE, SG or still the Allegro Lite?

just curious,

Kevin

[markdrela]

One MAJOR plus, having both wings that are clean (RDS) and wings that aren't (the OLD way), is that the wings without all of the 'stuff' hanging out of them, are easier to handle, store and transport etc.

Believe it or not, this is a major reason why I went with RDS on the Supra. The foam beds are permanently taped shut, and just slide onto the wing panels.

Unfortunately, this works on only one of the SG2 wings. The other wing has that darn finger peg sticking out. :rolleyes:

[lighthorse]

I just downloaded a set of plans for a 5m Fafnir I have a set of these
for Ailerons and Flaps, although I'll have to get the larger ones I think
it woul be great in Scale.


Lighthorse
Team YCS http://ycsoaring.com/headphones.gif
ycsoaring.com
Silence is Golden

[averen]

I'm pretty impressed that people can fit RDS into the SGII wing. There isn't much surface area back there to get the rod into...

If done properly RDS actually has a very nice mechanical advantage! The majority of the RDS installs that I've seen are extremely strong...much more so than your typical linkage.

Jared

[harleym]

I'm Harley Michaelis, LSF 023 and collaborated with Kimbrough Products to injection mold the servo accessory that can be used to install the Rotary Driver System. If you will go to http://genie.rchomepage.com and get into File 6 and into File 3 it refers you to, you will have the latest material on this method of moving surfaces. A CD with recently edited files has just been sent to friend Jay Decker for posting and it should be accessible shortly. Look for files with Jan. and Feb. dates. I'm now using Mark Drela's cantilever method of mounting servos for RDS installations. Much material on it is included in File 3, starting page 25. I employ 3/32" stainless steel for welding rods for "drive shafts" in my 145-1/2" span Genie and the 120" Genie LT/S. For the "pockets" I use either Formica, laminated CF spar material or CF plate, with spacers made from 3/32" basswood or hard balsa. Much information on these original design, sophisticated, scratch-buildable competition thermal ships is provided in the Genie web pages.

In looking at several posts by others on this forum, it appears that some guidance is needed to learn how to successfully do an RDS installation. The Genie pages should provide that help, but anyone is free to e-mail me at harleym@bmi.net, BTW. if you can't find a source for the Kimbrough couplers, I keep a good supply on hand for my personal use and am happy to make them available from me.