control rods inside the boom or out? - RC Groups
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Aug 16, 2009, 01:25 PM
planepainter's Avatar

control rods inside the boom or out?

I have seen a recent thread about how to secure the control rods inside the carbon boom. But I have also seen photos where the rods and sleeves are run on the outside. The inside is more visually attractive for sure but on the outside a lot of problems are solved. If they are secured to the outside, what tape is best? Can you use electrical or mylar packing tape? Perhaps heat shrink tubing that is shrunk to a snug fit around the sleeves? Thanks, PP.
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Aug 16, 2009, 02:55 PM
Registered User

Most DLGs have the control pushrods outside. The pushrods are usually either thin carbon rod or thin stainless steel, running inside etched teflon. The rod and teflon are stretched along the boom, and CA is wicked along for an instant, firm attachment. Result: fast, straight control runs. See for a very good instruction set. Also see Oleg's Taboo build instructions for another good set.

Some (and I have two that are set up this way) have the control rods (again, either stainless steel or carbon) inside a housing, NOT teflon but something thicker. I ran my control rods into the boom from the servos at the front, and out slots back at the tail. I used medium CA at both ends and they are fine.

My Taboo and Light Speed use the exterior rods. My Blaster II and Photon use interior rods. All four work fine, or did until other cosmic forces brought them to their demise. The Taboo went in on a hard launch with a servo unstuck. The Light Speed buckled a wing at the Blue Skies, but is flying again today.

You pays your money and you takes your choice.

Yours, Greg
Aug 16, 2009, 03:41 PM
Dragons, WindMills, all Same
jcstalls's Avatar
Outside: = 2 or > Function/Strength/Maintainance.
= 2 or < Pretty looks, like what girly types like
Inside = 2 or > Preety Looks and the same.
= 2 or < Function/Strenght/Maintaninance.


Last edited by jcstalls; Aug 16, 2009 at 03:47 PM.
Aug 16, 2009, 04:06 PM
Registered User
household goop, a little dab about every 3 inches. John
Aug 16, 2009, 05:00 PM
planepainter's Avatar
John, I assume that you mean on the outside?

Greg, if CA'd at both ends, don't your rods flex or bend in the middle?
When I built my Spirit, I had to cut a small access in the bottom of the fuse because the rods flexed in the middle even though both ends were CA'd solid.

I suppose that even a big plane with a boom instead of a wood fuse could be done to look nice with the rods running outside....

Last edited by planepainter; Aug 16, 2009 at 05:08 PM.
Aug 16, 2009, 05:33 PM
IBWALT's Avatar
I have done both the inside and outside and other than the cosmetic aspects there is no difference in either one. I am currently in the build it the easiest way you can mode so the outside the boom works for me right now. I currently attach the pushrod to the outside of the boom using only CA. I first position the pushrod on the outside of the boom and mark its position. Then I take some 200 grit sandpaper and knock the glaze off of the boom where the pushrod is going to set. Then I place the pushrod back on the boom and hold a little tension on the pushrod and then let some thin CA run down the pushrod securing it to the boom. Be careful and don't use to much CA and you will end up with a nice well bonded pushrod that won't be coming off anytime soon. I have used this technique on several DLG, XP 4 and 5 and a couple of Taboos and am currently flying a Super AVA that has the pushrods attached this way and I have never had a detachment.

Aug 16, 2009, 05:47 PM
planepainter's Avatar
Thanks as always Walt. I am also in the same mode you are and don't mind the idea of running them outside. But I am a bit picky about looks and did not want to mess something up. Your solution sounds great. I have a photo of an AVA from our club and it looks like the person used packing or filament tape to hold them on the boom.

Aug 16, 2009, 10:19 PM
Registered User

What IBWALT sez, is how I do the outside thing. Works very well.

For the inside: yeah, firmly glue the ends, with minimum slack between. Others tell me I'm wrong, but they work fine. They ought to work in theory, and so far in fact they work fine. On the Photon, I pushed a bit of foam down the boom, but otherwise, there is no middle support.

For the bigger airplanes, down the inside is much nicer, especially using the bigger pushrods. If the ends are anchored, that's the key - there is no place for anything else to move. At the same time, you can anchor the middle anywhere convenient, with goop, CA or epoxy, whatever.

I only have one model bigger than 2-meters, and I used the stock set up on that one: pre-installed pushrods, and they have been bullet-proof. My Dove 2-meter, I used Sullivan #507 pushrods (the smallest I could get) and they are fine for the rudder and elevator. I use Dymond D-60s for the flaperons, with an RDS setup. Simple, sweet, all the control anyone could desire. I'm contemplating a 2-meter RE sailplane (that I've built before) and I will use Sullivan #507s on the inside of the fuselage, with D-60 servos. It's a very nice, all-wood design, and should be less than 21 ounces.

Again: check out the Taboo build notes, and RCBuilder's construction notes for outside attachment.

Yours, Greg
Aug 17, 2009, 12:39 AM
Registered User
If you go on the outside, it's much easier if you use bondable teflon. I hear the stuff has a shelf life, so be sure it isn't too old. (I don't know how old that is.) I've seen a job where the stuff was no longer bondable enough and it just popped off. But if it's sufficiently bondable, it's very easy to get a neat job that is very rigid.

For the inside, one trick is to use plastic or teflon pushrod tubing attached on either side of a long stick that you put into the boom. This is commonly used on the Mantis and some of its relatives. Be patient and make sure everything works just right and doesn't stick. It will pay off in better handling and longer battery life.

If you've got an existing fuse that's got buckling in the pushrods, it's no fun. You can take chunks of foam, maybe EPP from packaging, and make little plugs to stuff down the boom with a stick at intervals to support the pushrod housings. It's not too hard to do, but it's worth planning out first so you don't have to try to extract any of the foam pieces, which isn't so easy. Put in an extra tube for the antenna while you're at it.
Aug 17, 2009, 02:50 AM
Suspended Account
WARNING: The following opinion is from a Woody builder who's never owned a composite-anything.

Painter. As a big-time woody guy who probably enjoys the 'art and aesthetic' of sailplanes maybe even more than the flying; I'd say that by the time one is using a Pod & Boom fuselage they've already crossed the form / function line in favor of function.

Pods & booms produce a fuselage at the lowest possible frontal area, weight and posses arguably the greatest strength. They are made for function and not beauty. Don't sweat it; for ease of maintenance put the rods on the outside and be done with it.

On my next plane (hopefully Supra) I'm gonna do it that way.

-Sean (A guy who's ready to have an airplane that he can just fly and not worry about so much)
Aug 17, 2009, 08:28 AM
planepainter's Avatar
Thanks guys for this great stuff. I can now go forward knowing that I can pull this off. Lincoln, I had read about the foam thing before but thanks again for reminding me. PP.
Aug 17, 2009, 09:38 AM
The Flying Kiwi
One handy hint I've used for unstuck or loose /stubborn tubes is to wrap them about 1-2 times with masking tape, then CA them in place. Quick and easy!
Aug 17, 2009, 09:48 AM
Hot Dawg Glider Pilot
schrederman's Avatar
I'll be building the Journey sailplane soon, and will do a build log. I plan to do the pushrods inside. I will sand the inside of the boom and clean it out with 99% isopropyl alcohol. I'll coat the etched teflon with epoxy for the elevator and lay it in the top of the boom It will be attachd for the entire length. The way I attach my fin to the boom, there's no need for slotting the boom anywhere. The rudder pushrod will be attached the same way. This will all be done before joining the pod and boom.

Currently I'm waiting for the pushrod sleeves and the rib sets. I have everything else to start. The fin/rudder assembly is in progress.

Aug 17, 2009, 10:45 AM
planepainter's Avatar
Hi Jack. I will be looking forward to your log. BTW, where can I get good push rods and sleeves at lengths? I will need longer and lighter ones than DuBro provides. Thanks, Don.
Aug 17, 2009, 12:52 PM
IBWALT's Avatar
There is a post on RCG somewhere that describes what I think is the best way to install the pushrods on the inside of the boom. This link describes the process. Like I said before there is a post with pictures and everything but I can't find it. So this description will have to do.


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