Retract Servo?

[RShelby]

A drop or two of oil on everything that moves can make a big difference in the force it takes to operate a retract. A bit of grease may be necessary on any sliding parts.

Rick
Team Horizon

[Mark9]

I tried the oil trick first to no avail. Still had to be manually forced into the lock out position. When I looked very closely I could see part to part contact for what should have been a non-contact fit. Maybe if the paint was not on either part it would work correctly. The simplest fix was to bend the channel flanges until I achieved a non-contact fit. Again tolerance build up in high accuracy assemblies can eat you up. Don't get me wrong the quality of this airplane is awesome for the price!!! Also, a big shout out to the team at Soaring USA. Alex steered me to an airplane that fit my restraints and I think I will be happy with.

[Wild Doogie]

First I made a mold to fit around the tow release tube and arm out of a clear plastic bottle top. Mixed

7 ounces of #8 lead shot with enough slow cure epoxy to give a light coating. Made sure that the mold was secured and waited until the epoxy was tacky.With the fuselage vertical, nose down, I filled the entire nose. I needed another 2 ounces after the second estimated C of G and that was a lead bar secured to one of the LiPo batteries far forward. After the first flight it needed 2 more ounces.

[Mark9]

Wild, thanks that gives me a confirmation of about how I had planned to do my nose weight installation and a ball park of how much to plan for. My installation plan is to epoxy a spent toilet tissue roll in the nose with some real thick 5 or 15 minute cure. It would then be sacrificed and cut down if needed after the pour. With the slurry of lead shot and epoxy who cares that a little cardboard is in there? Its purpose is to keep the pourable mix out of the tow release and allow access to the clevis if needed.

Here's another tip I used when "tweaking" my retract. When installing it the first time I took it out it was a pain to find the mounting holes for the bolts. Before the second time I made some registration marks with an extra fine black Sharpie on the fuselage structure. This then let me know if I was close to finding a hole in the fuse. I also installed one of the ones in front first. Then by lifting the back I easily, relatively speaking, found the holes for the back ones.

[Wild Doogie]

Thanks Mark, that will help with installing the retract. Use slow cure epoxy to prevent overheating or place a cold towel on the outside. I believe my CG starting point was around 95mm from the leading edge or about 33% of the cord. On the rudder I installed a pull-pull system located in back of the retract frame. The push rod on this KV was very cheap so I decided to remove it. A lot of extra work but worth it.

[Mark9]

I was initially thinking of a pull-pull system too and the cheesy pushrod with no mating hardware meant I had to do something. But, my pragmatic side took over. The location where the pull-pull would need to go, installation, set-up and future maintenance made it a non-starter. So, I delved into my stock of carbon and found three carbon pushrods that might work. One was used with a 2 mm coupler on one end and another was brand new with no fittings. Both of them were greater than .060" dia. and a little tight in the existing housing. Also, in my stock was a pair of .050" x 60" rods with housings and it was like Goldilocks, just right. Still was a fiddly installation right at the front of the retract structure. But, the installation is solid and relatively easy now to maintain and adjust.

[Wild Doogie]

I was wondering if would you post photos of the retract servo position and carriage in full extension, half position and full retract when you get a chance. Are you going to run a 2 cell LiPo just for the retract and tow release together?

Thanks,

Doug

[Mark9]

I'll try to get some photos up later today, have some things to do this morning. It is in the airplane now, so the servo positions may be a bit difficult to see...will need to try.

No, the retract will be the only servo on a separate isolated battery source. The battery I made from some original A123 1100 mah. 18650 cells I had, spares when I built a battery for my Supra Pro. With all the function testing and debugging I estimate I should not need to charge all day. However, it is a simple process at the field with my field charger in about 30 minutes. My retract servo is the only non-HV servo in the airplane.

The other battery is a LiIon 18650, not sure what brand, that SUSA put in my package when I ordered my 2CX. I believe they are Sanyo/Panasonic 2300 mah. LiIon. Since my radio Is a SD-10G and with my preferred set-up they will both be operated by a single switch through a Smart-Fly II I have from another airplane.

I'm not a big fan of LiPo batteries. They typically are fragile, need to be placed in storage mode if not used regularly and more prone to crash damage. One major detractor is they can catch fire if punctured, unless they are the hard case versions. That would require some major damage with the 18650 can batteries, most unlikely to happen. When properly handled (charged) the "E-cIg" batteries are safe and a good HV power source.

[Mark9]

Doug,

Here are the pictures. In the first one the wheel is totally retracted. In the retracted position the servo arm almost contacts the cross bar. That results in no effective load on the servo, the linkage is in line with the servo output shaft.

The second picture shows the wheel about half way extended. The two red arrows are where I made "adjustments". The system would not work with my servo/arm configuration without the metal being removed from the aluminum plate in the nut recess.

The other arrow shows the channels I had to adjust the flanges on. As I said all it took was a good pair of pliers. I doubt any servo would have engaged the lock out position in the down mode. It would have needed to be a monster. It felt when I engaged it manually like a retention pin with a spring and ball being inserted, not smooth.

The last picture is of the wheel fully extended. One key is getting the linkage length into the "sweet spot" so both ends of the travel are correct. If it's too long the doors won't close. But if it's too short the down position will not be engaged properly. Adjusting it is a pain in the posterior since it has to be in the aircraft to see if the doors close. That could be easily achieved if a threaded rod with opposing threads was used instead of just plain threaded rod, similar to a turnbuckle. But, to do that it would need to be a "custom" assembly with left and right handed threads. Hope this helps.

[Wild Doogie]

Mark, sent you a PM

[Wild Doogie]

Thanks for your battery setup and your retract photos.