Official Freewing 80mm EDF F-86 Sabre Thread

[Oxotnik]

It didn't feel like a spin to me, but it did seem to be entering a spiral, as it went behind the trees. I'd certainly been pulling 90° bank turns during this same flight, without any indication of a stall. Maybe pushing my CG back AND dropping gear in that turn caused the turn to become unstable. I'll think about it some more. Thanks for your thoughts.

[Evoman]

I killed my Sabre today. I'd moved the CG back, so that she would almost stay on her tail when the tail was pushed to the ground. The takeoff, climbout, and flight was great. She gave me no indication that she may be tail heavy. I even pulled some rather tight Immelmanns, and if she were close to being tail heavy, I've have expected her to snap roll out of the high-g half loops. As you can see in the video, I was turning onto the downwind leg, gear deployed, when I lost her. As I was coming onto the downwind, she was in a descending 90° bank (a maneuver that I've done a million times with no problems), but when I gave her the commands to level out, she was unresponsive and stayed in the diving turn, becoming a spiral of death. It felt like a brown-out, but I'm having trouble buying a brownout because I was using a standalone UBEC. I've dropped gear in turns like that, without incident. Maybe a combination of dropping gear (adding drag), throttling back as I was setting up landing, and having the CG farther back than I've ever flown her before. I'd appreciate your thoughts. If I dumb-thumbed it, I'm not afraid to admit it.

As soon as it I read your post I had a good idea of what may had happened. I have experienced the same thing while flying my F-86 Sabre but in the DCS flight simulator several times.
This is referred to as an aggravated stall. It would mostly occur when doing sudden turns.
Here is a good video that explains it and teaches how to recover from one.

[Oxotnik]

I killed my Sabre today. I'd moved the CG back, so that she would almost stay on her tail when the tail was pushed to the ground. The takeoff, climbout, and flight was great. She gave me no indication that she may be tail heavy. I even pulled some rather tight Immelmanns, and if she were close to being tail heavy, I've have expected her to snap roll out of the high-g half loops. As you can see in the video, I was turning onto the downwind leg, gear deployed, when I lost her. As I was coming onto the downwind, she was in a descending 90° bank (a maneuver that I've done a million times with no problems), but when I gave her the commands to level out, she was unresponsive and stayed in the diving turn, becoming a spiral of death. It felt like a brown-out, but I'm having trouble buying a brownout because I was using a standalone UBEC. I've dropped gear in turns like that, without incident. Maybe a combination of dropping gear (adding drag), throttling back as I was setting up landing, and having the CG farther back than I've ever flown her before. I'd appreciate your thoughts. If I dumb-thumbed it, I'm not afraid to admit it.

[Porkster]

After flying my Sabre twice today. I noticed that the grub screws holding the struts on are not tight. The struts do not rotate, but they move (extend/shorten) about an 1/8". I couldn't break the thread lock with my hex tool. What's the trick to break the thread lock? Heat the grub screw with a soldering iron?

Yep, a little heat should do the trick

[Oxotnik]

After flying my Sabre twice today. I noticed that the grub screws holding the struts on are not tight. The struts do not rotate, but they move (extend/shorten) about an 1/8". I couldn't break the thread lock with my hex tool. What's the trick to break the thread lock? Heat the grub screw with a soldering iron?

[e4dragongunner]

Excellent
Many many thanks!!!

[Oxotnik]

Oxotnik, now that you've got some time on your Sabre you may want to experiment with doing what you can to move the CG back. It lands, takes off and flys a lot better with a more aft CG. If your interested. It's great model either way.

I have moved the battery back another inch or so. I removed the battery retainer and carved out the bottom of the canopy/battery hatch. The CNDL 6S-4K is still too fat to move all the way to the back to the bay. The Admiral 6S-5K is a little wider and thinner and can be moved further back. I do want to the push the CG a little farther back, hoping that the F-86 will rotate a little more quickly. The Sabre will take off from grass, but it certainly helps if I can hit a bump to help it get airborne. LOL

[Beeg]

Some guys are running 200mm with the "tail sit test". If you search the tail sit test in the Sabre thread at RCG there is much discussion about the various CG's folks are using. Without adding weight I think I have mine around 170-180mm but I run 6000mAh batts so it's hard even with my ESC moved out of the way and batt shoved back against the foam cross member to get it much further aft. Most guys have to add weight to the tail.

you can start here.. https://www.rcgroups.com/forums/show...0#post31279337

[e4dragongunner]

Hey Beeg, What is the alternate CG from stock? Thanks :-)

[Beeg]

Oxotnik, now that you've got some time on your Sabre you may want to experiment with doing what you can to move the CG back. It lands, takes off and flys a lot better with a more aft CG. If your interested. It's great model either way.

[e4dragongunner]

Agreed!

[T-CAT]

Even though wing removal is easy with the four screws and plastic joiner, it's a pain to reconnect all the servo leads and ensure they get reattached perfectly out of the airstream since a plastic tube halves separates the wiring connections and the intake. It's a jet I would prefer to keep in tact because of this.

[Topshot19]

how is wing removal for transport with this jet?

[Oxotnik]

I visited an RC Club yesterday, in my hometown, and flew several planes, including the Sabre. It was my first time flying on a paved runway, narrower and shorter than my home grass field. Takeoff from a paved surface was definitely easier, as I was able to rotate much more quickly than on grass (no surprise there). For landing, though, I had to wave off the first three approaches, then had to land on my fourth (as I was almost positive that I'd be out of battery after one more climb-out). With super-human concentration, I put the plane down just off the centerline, a little faster than normal (as I had a bit of crosswind), and I thought that the dang plane would never stop the roll out. All in all, it was a very fun day flying (also flew my FlightLine P-38 and Freewing FW-190A) and I made some new friends.

[Jim Talley]

Haven't flown my F-86 in quite a while. Took it out this morning and did 4 beautiful flights. What a great airplane!! Gonna take it out again tomorrow along with the A-6 and twin 64 A-10. Life is good.

Jim

[Oxotnik]

Yep, that was one of the big takeaways from my first 3 flights of the F-86... I can't horse it around like I do my prop warbirds. I was scared to try anything more than an axial roll. I didn't even do an Immelmann, although I don't doubt that it can, provided it has plenty of speed going into it. I'll test its limits more after I get comfortable flying and landing it.

[gooniac33]

Getting a feel for mine. Im so used to flying the smaller 64mm to 70mm jets with their squirrely characteristics, that this big one threw me off but I think I got the hang of it. You have to fly it more scale like a real jet it seems..

There you go....

[Model jet juggernaut]

Getting a feel for mine. Im so used to flying the smaller 64mm to 70mm jets with their squirrely characteristics, that this big one threw me off but I think I got the hang of it. You have to fly it more scale like a real jet it seems..

https://youtu.be/bEFU6p8umRs

[Oxotnik]

I maidened my F-86 this past Saturday with no problems. I used a CHL 6S-4K batt, with battery pushed back to the ESC retainer. The F-86 was slow to lift off and climbout, but flew great. No horrible landings. On the maiden landing, I actually had two good landings, as we say at the field, or a touch-n-go and landing 15 ft later. LOL
Second flight was great, with a greaser of a landing.
Third flight was wobbly. I think that my LemonRX receiver may have been loose (I'd turned on stabilization due to the gusty winds). The left gear popped out during the third landing, but that was a 5-minute repair.

Love the F-86. You guys did not steer me wrong. Here's a dust-in-the-sky composite video of my first three flights: https://youtu.be/qqaqDMmYryY

Over in the 'what did you fly today' forum, I've gotten advice to move the battery back, to help with a quicker rotation and climb out, and probably a little less up elevator trim. I have moved the battery back on top of the ESC. Should I be concerned that the ESC will put too much heat into the battery? I also had to cut some foam out of the battery hatch to accomodate the aft position of the battery.



[edit] I just put an Admiral 6S-5K in the Plane. The Admiral 5K is a bit thinner than the CHL 4K battery and fits much better in the bay than the CHL. Guess I know which battery I'll be flying from now on... :-)

Are there any other recommended mods?

[Oxotnik]

Thanks guys! I was just about to ask if an Admiral 5K would work. My CHL 4K came in today, but I don't have an XT90-EC5 adapter and don't feel like rushing to the LHS to grab one and charge the battery in the morning. IMve got my Jolly Roger ready to rock and roll. Wish me luck tomorrow.