Official Freewing 80mm EDF F-86 Sabre Thread

[Dave Wave]

Thanks for all the good info. I think I am going to take the re enforce/ big tire route and see how it goes. Our field is not that bad and if I have issues, I can always try to hack in trailing link if the stock struts do not work out.

I appreciate the help.


-Dave

[paulrkytek]

So the C shaped ply is like the top of a sandwich? You just inset it into the foam and glued it to the retract mount?

Yes Dave, ply is glued to both the foam and the top surface of the back box, you may need to trim the wing foam level with the back box top surface. I lifted the actual retract servo about 3mm with spacers to get clearance for the wheels I used so that the wheel did not bottom out and stall the servo motor and kick in the overload sensor. The oleo covers are bent/creased so that the leading and trailing edges sit back into the wing surface otherwise there would be lip. You can still unscrew the servos afterwards using this method. Landing on grass in this video is after the mods

https://www.youtube.com/watch?v=VvCUGzz3e_k

[paulrkytek]

Thanks for that, I will certainly do that when I get the model. Now I need to decide if it is worth the effort to try to add trailing link gear as well. The combo of the two would probably be bullet proof, but the are certainly some aesthetic and cost issues as well.

I cannot see how you could add trailing link mains gear unless you bend the connecting pin forward and cut out some foam to accommodate the raked forward oleo leg as you cannot move the wheel wells back to accommodate the retracted wheel resting position or there will be nothing to hold the wing fixing bracket in place. Though I suppose you could re fix the back boxes further forward by about 20 to 25mm but its a lot of work carefully cutting the foam as there is not much margin for error before you break through the top wing surface and building back the foam in the original back box hole and then making good the wing surface finish. Good luck whatever you decide to do.

[Dave Wave]

So the C shaped ply is like the top of a sandwich? You just inset it into the foam and glued it to the retract mount?

[paulrkytek]

The gear back boxes do not have a big enough contact area with the surrounding foam and leaving the bottom out of the back box did not help. I re-fixed mine with gorilla glue and I also
replaced the thin cosmetic silver plastic cover strip with 1/16th ply U Shaped cover strips from a 70mmx60mm rectangle glued to the exposed surface of the back box and the surrounding foam in order to achieve an additional 10mm or so width of pressure spread from the back box to the foam surface. I fly off grass and so far so good. I just finished the ply surface off with peel and stick silver film. I also made the wheel wells a bit bigger and replaced wheels with 2.25 inch wheels and replaced the oleo covers with bent ply covers to match. ( these replaced the ones I cracked when one retract flew out on a pretty gentle landing mainly due to the lack of glue and poor contact area.)

[Dave Wave]

Thanks for that, I will certainly do that when I get the model. Now I need to decide if it is worth the effort to try to add trailing link gear as well. The combo of the two would probably be bullet proof, but the are certainly some aesthetic and cost issues as well.

[C17loadmaster]

If they are re-glued, do you think the gear is suitable for grass?

With the landing ear extended, pull the MLG servo lead out of the notch in the wing so that it has slack up to the hole in the wing leading to the RX. Then grab the entire completed strut (wheel and retract installed as if it were ready to fly) and gently yank straight down. You will be surprised at the ammount of resistance needed for the entire wing mount to completely seperate from the wing. Then, do the same to the other side. Take whatever glue you want (gorrilla, epoxy, the supplied glue from the factory) and reapply a very generous ammount in the wings where the plastic retract mount was removed. Push the entire assembly back into the wings one at a time and let the glue cure.

-You can just rest the airplane upright on its extended gear so that positive pressure is applied. I personally would set a 6s lipo on top of the wing above both of the retracts during cure time. It will keep the mount seated correctly and you can gently roll the plane forward to ensure there arent any alignment issues.


After that, you can fly off grass all day. Its got to be cut to around the lenght of a golf course "rough", or else it will take up a ton of room and battery to get airborne. If you leave the retracts alone and do nothing, they will evenually rip out on their own just as I explained above. Coming unglued during a landing will guarantee the sharp corners will gouge the heck out of the undercarraige and your flap servos will strip.

Mine is extremely old, and been rebuilt after crashes a few times. Swapping the servos for the flaps from 9g to 17g metal gear was a worthy upgrade.

[gooniac33]

Back in the day it was possible to adjust servo centering by inserting a tiny screwdriver through the hole in the output shaft and adjusting the pot. The pot had a screw slot just for this. I don't know if today's servos allow this or not?

I remember seeing this. SANWA had this if I remember right... been a long time though...

[Dave Wave]

I also installed trailing link struts but that required some foam removal. I don't fly my Sabre from grass as I do my Venom.

I was thinking of going this route. Do you remember which struts you used? Did you just change the strut and use the installed retract? How much foam did you have to remove?

A picture would be fantastic if you have one...

[xviper]

If they are re-glued, do you think the gear is suitable for grass?

Depends on how you land. If you're still thumping it down, that initial high resistance from the grass could still rip out the retract - actually, it'll rip out the retract housing and the foam it's glued to. If it were me, I would push (and glue) tiny CF rods or strips into the foam almost the thickness of the wing section and then glue the retract mount into all that.
I don't know how much bigger tires you could put on this plane but I would maximize the diameter of the tires to make it roll easier. As with my FW Venom, I also installed trailing link struts but that required some foam removal. I don't fly my Sabre from grass as I do my Venom.

[Dave Wave]

Even on a soft landing (maiden flight), one of my main gear mounts pulled right out. Wasn't glued in very well. Then on the next day's flight with it, the other main gear pulled out. This was landing on GeoTex and rolling up onto the grass. Thinking back, I should have just grabbed each main gear and gave it a good, solid yank just to get it over with.

If they are re-glued, do you think the gear is suitable for grass?

[xviper]

Do you have link for the .STL file?

Is it only the nose gear with issues? I assumed the mains would have problems without trailing link gear.

Even on a soft landing (maiden flight), one of my main gear mounts pulled right out. Wasn't glued in very well. Then on the next day's flight with it, the other main gear pulled out. This was landing on GeoTex and rolling up onto the grass. Thinking back, I should have just grabbed each main gear and gave it a good, solid yank just to get it over with.

[Evan D]

The brace really helps on planes where the gear extend forward. Limited benefit on this. Plus the retract mount on this is pretty well designed…

for the mains, other than the re glueing of the mount they do okay.

[Dave Wave]

Do you have link for the .STL file?

Is it only the nose gear with issues? I assumed the mains would have problems without trailing link gear.

[SanExup]

There are nose gear braces for the F86 available to buy or to print. My Sabre, future Fury, shows up tomorrow and I already have the brace. I'll post a photo when I install it.

I'm planning on flying it from grass. I'm considering belly landing it if the grass is too long to cleanly land it without damaging gear. But I don't want to shred the belly either.

[Dave Wave]

I am going to be flying of a rough grass field. I am a bit concerned about the landing gear being on the weak side. Is it possible to reinforce it so grass ops are not an issue?

I know it might be sacrilege, but has anybody converted this to trailing link gear? I have an Avios jet with such a gear and grass has not been an issue with the stock gear.

[Evan D]

I've been flying well over 50 years and while I have heard of this I've never seen one. Any idea of brand and model servo?

Also used to be on some, I used Futaba mostly, there were little screws holding the pot in the case and you could loosen the screws rotate the pot and then tighten it back down. Now they are friction fit, you may be able to do something similar but really most planes aren't effected by a little more throw to one side.

Many digitals are programable for end point, centering and direction (a lot of the Hitec are)...

Back in the day it was possible to adjust servo centering by inserting a tiny screwdriver through the hole in the output shaft and adjusting the pot. The pot had a screw slot just for this. I don't know if today's servos allow this or not?

[paulrkytek]

My F86 with 12 blade in-runner at the field today

https://www.youtube.com/watch?v=VvCUGzz3e_k

[paulrkytek]

I need some help.
On the 86 the elevators have one standard servo and one reversed. Mine do not center the same leaving the servo arms at different angles causing the elevators to have a different amount of total throw. They are about half a cog difference so moving one servo arm one cog does not fix the problem. I corrected the problem by plugging one servo into an auxiliary channel, mixing it with the elevator channel, and then adjusting throws to get an equal amount on each elevator. I would like to get back to the two servos on a y harness and using just the elevator channel so that I can add a stabilizer. Any ideas?
Thanks

You could add an arm at the side of the servo arm using a couple of tiny bolts/screws and epoxy then re drill the hole to match the position of the second elevator that way you are starting from the same pivot point

[radfordc]

I need some help.
On the 86 the elevators have one standard servo and one reversed. Mine do not center the same leaving the servo arms at different angles causing the elevators to have a different amount of total throw. They are about half a cog difference so moving one servo arm one cog does not fix the problem. I corrected the problem by plugging one servo into an auxiliary channel, mixing it with the elevator channel, and then adjusting throws to get an equal amount on each elevator. I would like to get back to the two servos on a y harness and using just the elevator channel so that I can add a stabilizer. Any ideas?
Thanks

Back in the day it was possible to adjust servo centering by inserting a tiny screwdriver through the hole in the output shaft and adjusting the pot. The pot had a screw slot just for this. I don't know if today's servos allow this or not?