Flex Rod for Dual Elev??
 

Building a Venus 40. Would I be able to use The plastic Flex-rod pushrods in place of the regular metal pushrods? I fgure they will bind less within the push rod tubes through the slight bends. I will need to join the two rods in the servo area to run off of a single servo. Would this work? Its not too bad...but there is a little resistance in the pushrod tubes and would like to make sure I dont kill the servos from any strain in the air. Am I being overly cautious?


Has anyone relocated servos to the tail?. This is a great looking little plane...but could have been designed a little better in terms of servo placement for performace/linkage setup. Also in the stock config, they chose to use two linkages off of one servo on the elevator. If using only one servo, why not join the elevator and have it operate as a single unit?

RE: Flex Rod for Dual Elev??
 

I had the Venus 40 which was powered by a Saito 72 and some time later with a Saito 82 (Both will fly it with enough power), after assembling I noted that it came nose heavy and I relocated the battery to the back of the servos compartment (at the headrest of the cabin but inside the fuse), servos were located as indicated in the manual, after several flights I decided to add some weight to the tail (About 1 oz of lead). The plane had a bad crash and I just do not want to repair it by now, even that it was a great flier and a good practicing bed for pattern maneuvers.
If I had to assemble a new one I definitively would use again the Saito 82 and put two miniservos at the real to control the elevator halves, leaving only one standard ball bearing servo to control the rudder and one micro servo to control the throttle at the servo bay.

RE: Flex Rod for Dual Elev??
 

Roland,
Just wanted to let you know that last night I moved my battery and and receiver (small Futaba 2.4) as far back as I could in order to balance. But, not as far as I would have liked. I still had to add 1/4 oz weight to the tail in order to get it to balance at 4 3/4". I could have left my receiver in area were the plans say to install and hold in place with balsa sticks. With my receiver in the location shown in the plans, my battery needed to be installed RIGHT were the elevator and rudder servos are. So instead, I put the battery under the servo tray, right up next to the throttle servo, and mounted the receiver to the balsa peice that is the back side of control panel. The reason I am telling you all this (even though you asked about flex rods) is because moving to a single servo in the tail and joining the elevator halves sounds like a real good idea. I wish I thought of that! That would leave you with a lot more room to move the battery and receiver around for proper balancing. Also, I haven't checked into this yet, but since I am using the OS55 with a bisson muffler, alum back spinner, and MAS 13 x 6 prop, I probably have more nose weight than the plane was designed for. Hope this helps.

RE: Flex Rod for Dual Elev??
 

MESA...i WAS JUST TRYING TO UNDERSTAND THE DESIGN CONCEPT BEHIND SPLITTING THE ELEVATOR - YET STILL USING THE SINGLE SERVO AND 2 PUSHRODS VS JOINING THE ELEVATOR AND USING A SINGLE ROD ON A PLANE THIS SIZE.

THAT MIGHT BE A NICE PROJECT...MINI SERVOS IN THE REAR WITH CARBON TUBES AND BALL LINKS FOR ALL LINKAGES.

GLAD TO HEAR YOU ARE GETTING INTERESTED IN FIGURING OUT THE CG. I WARN YOU - PLEASE PLEASE PLEASE BE CAREFULL. MAKE SURE THAT WHEN YOU REBALANCE THE PLANE IT STILL SITS CLOSE TO LEVEL. IF YOU MAKE IT VERY TAIL HEAVY IT WILL BE HARD TO CONTROL. I WOULD NOT MAKE DRASTIC CHANGES. BALANCE THE PLANE ON THE GROUND USING YOUR BALANCER OR WHATEVER METHOD YOU HAVE CHOSEN - THEN MAKE VERY SMALL CHANGES BASED ON THE TECHNIQUES I TOLD YOU ABOUT. THE CHANGES MUST BE VERY VERY SMALL SO THAT YOU WILL STILL BE FAMILIAR WITH THE CHARACTERISITCS OF THE PLANE IN FLIGHT. LIKE I SAD BEFORE. IT MIGHT TAKE YOU 10-20 FLIGHTS BEFORE YOU FIND PERFECTION. ANYTHING YOU MOVE BACK SHOULD BE MOVED ONLY ABOUT 1/4 INCH AT A TIME. KEEP ME POSTED. I REALLY WANT TO KNOW HOW YOU MAKE OUT.

RE: Flex Rod for Dual Elev??
 

One problem with flexible plastic rods like Sullivan Gold-N-Rod, Ny-Rod similar is they will change dimension with changes in weather. I used to fly Gold-N-Rods but have changed back to using hardwood dowels or metal push rods, both of which seem to work better.

If you use the plastic flexible push rods be prepared to make mechanical changes to your plane periodically as the weather changes from hot to cold and back. Also setting a plane up with plastic push rods in a cool basement and taking it out to a flying field when the weather is hot will make them expand and you’ll could sit there and wonder what happened to your plane when you see all the control surfaces everywhere but where they should be.

Hogflyer

RE: Flex Rod for Dual Elev??
 

OK ...scratch that idea!!!! Thanks hogflyer!!!

RE: Flex Rod for Dual Elev??
 

Roland,
You got my attention with all the yelling (CAPS)! Hey, just kidding!!! But seriously, it made me realize that I didn't like what I had done to move things around. So I took everything apart and relocated the receiver (small Futaba 2.4) were "alfredbmor" put his battery. It was a little bit of work, but it came out A LOT cleaner. By doing this, I was able to eliminate a 6" servo extension that went to the volt watch. It also allowed me to remove the tail weight, and have more of an area to move the battery around in. It also balanced "dead on" the recommended CG starting point. And, if I add a 1/4 oz weight to the tail, it moves the CG back 1/8". I feel a lot better about the whole thing. Should be flying tomorrow, so I will let you know how it goes.
Thanks for pulling my head out of the sand!
Pete

RE: Flex Rod for Dual Elev??
 

my favorite material for push rods is carbon fiber arrow shafts. Long ones from walmart sports dept could be bought on sale for $2.50 after hunting season. stock up if they get this cheap this year ...everything is going up.
I like 'em because they are light enough not to tear up servos so much when OOPS happen.

RE: Flex Rod for Dual Elev??
 

I used Sullivan Carbon Rods, a pair of them, side by side to a common connection at the servo in the servo tray. They fit in the existing tubes supplied in the fuselage. On the rear end, I allowed the carbon rods to extend out the holes for about two inches or so. For the steel rods that go in the carbon rods, I took the rods, held them with pliers, chucked the steel rods in a variable speed drill, put a few drops of CA on the steel rods, then pushed them in the center hole of the carbon rods while the drill was turing at medium speed. I pre-measured the length of the rod to go into the carbon rods and marked the steel rods so I knew how far to push this in. You have to work fast because the CA will sieze up pretty quickly, but initially, it acts as a lubricant so push them in quickly to the pre-measured line then stop. They will be fine.

When making the measurement for the steel rods, make sure that you measure far enough so that the combination of the carbon rods and the steel rods go in the fuselage far enough so that the carbon rods do not flex outside the fuselage.

I've flown this setup now for a couple of years and it's solid, reliable, and very light.

CGr.

RE: Flex Rod for Dual Elev??
 

Carbon is the way to go,

http://www.centralhobbies.com/contro...e/pushrod.html