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Official Freewing MiG-29 Fulcrum Twin 80mm Thread

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  • He said upgraded FW ones.

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    • Originally posted by Evan D View Post
      How many on here, when pushed, don’t have a clue where they’re balanced at???
      You may have a good point. (However, NOT putting my hand up.) Mine is balanced 10mm aft of the marks.

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      • Could this be the cause of the crashes?
        Take a look at the fixing screw that holes the elevator on the shaft. The head of the set screw will imbed into the foam of the elevator and possibility stick. Maybe a grub screw would be a better choice to secure the elevator.
        Yes, I had mine go in and it definitely was a elevator problem.

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        • Hi Duke...Can you provide details of your set-up, radio config, whether or not your crash was with the flaps down, etc. Regarding the flaps...since you reported it happened shortly after take-off, can you confirm you retracted the flaps?

          Videos show flaps down and faster speeds is not a safe combination.

          -GG

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          • Just take a look at your elevator and see if the set screw has imbedded it shelf into the elevator. The first time this happens with a lot of pressure it may stick?

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            • Originally posted by duke View Post
              Just take a look at your elevator and see if the set screw has imbedded it shelf into the elevator. The first time this happens with a lot of pressure it may stick?
              Are you saying this was the cause of your crash?

              it is not clear to me how the set screw could get to be on the foam side of the cavity. When the plane is turned upside down for installing the FFS, the cavity in the FFS is down. The set screw is up...and away from all foam. To have the set screw on the foam side, you’d have to tighten it by digging a hole in the FFS???!!!

              -GG

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              • If you installed it off to the side and then gave it up or down it would bind, not hard to picture...

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                • If the set screw that holds the fixing ring is installed as per the instructions on page 4 it will bind when pressure is applied.

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                  • Originally posted by duke View Post
                    Could this be the cause of the crashes?
                    Take a look at the fixing screw that holes the elevator on the shaft. The head of the set screw will imbed into the foam of the elevator and possibility stick. Maybe a grub screw would be a better choice to secure the elevator.
                    Yes, I had mine go in and it definitely was a elevator problem.
                    That is a really interesting idea, never thought of that. I tried to get it with the head straight down, but even with it straight down, at full rotation, it is not far from the walls of the cavity. And if it isn't exactly straight down, who knows. Will definitely take a look at this. The manual says "PM2 x 4" for the screw size, which probably means it is M2...?

                    I find a bunch of "assortments" on Amazon. Here is one that just has M2, but it is not much cheaper than buying an assortment:
                    https://www.amazon.com/Uxcell-a16022.../dp/B01FF3JKMA

                    Edit: After further thought, wouldn't this mechanism tend to stick the ele at full deflection one way or the other? That is not consistent with what we are seeing, with ele basically centered and not responding.

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                    • Originally posted by duke View Post
                      Could this be the cause of the crashes?
                      Take a look at the fixing screw that holes the elevator on the shaft. The head of the set screw will imbed into the foam of the elevator and possibility stick. Maybe a grub screw would be a better choice to secure the elevator.
                      Yes, I had mine go in and it definitely was a elevator problem.
                      They use the same system on other models with FFS, such as the Sukhoi 35, F-14 and F-22. I am not aware that any problems have been reported on those models, which have been around for a lot longer.

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                      • I think if the elevator gets stuck due to the head of that screw embedding itself in the foam of the stabilizer, that elevator would be at one of its extreme deflections (either UP or DOWN). Being that way, if one is stuck, then we would see a corkscrew. If both are stuck, then we would see either a climbing or a diving arc.

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                        • Originally posted by Evan D View Post
                          If you installed it off to the side and then gave it up or down it would bind, not hard to picture...
                          The instructions show it installed straight down ("up" in the picture with the plane inverted), not off to the side.

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                          • Just in case this is the problem I'm going to use grub set screws in my rebuild. I think this may explain the erratic crashes.

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                            • Hi Duke...Can you confirm that your flaps were up when your crash happened?

                              Flap vs faster speed has been shown to be a contributor.

                              -GG

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                              • Yes the flaps were up. I had just took off( put ldg/flaps up) made a right turn and was going to make a slow pass over the runway, then the plane started a slow to fast dive. Just before hitting the ground it seemed to pull up a bit. The elevators have deep indention where the set screws were hitting. Boot elevators were function after the crash.

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                                • I had the MRC upgraded servos with 4-40 ball links.

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                                  • Originally posted by Skittercat View Post
                                    I had the MRC upgraded servos with 4-40 ball links.
                                    Hi Skittercat - Thinking back on it, do you feel you might have been in a nose down stall (ref: my prior post) which would have made recovery impossible just by holding up elevator? Remember, aircraft can stall at any attitude and airspeed. All that is required is to exceed the wing’s critical angle of attack.

                                    -GG

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                                    • Originally posted by duke View Post
                                      Yes the flaps were up. I had just took off( put ldg/flaps up) made a right turn and was going to make a slow pass over the runway, then the plane started a slow to fast dive. Just before hitting the ground it seemed to pull up a bit. The elevators have deep indention where the set screws were hitting. Boot elevators were function after the crash.
                                      Just curious, were you on downwind or making a 180 degree right turn back to the runway?

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                                      • 180 rt turn back to the runway.

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                                        • Originally posted by duke View Post
                                          Yes the flaps were up. I had just took off( put ldg/flaps up) made a right turn and was going to make a slow pass over the runway, then the plane started a slow to fast dive. Just before hitting the ground it seemed to pull up a bit. The elevators have deep indention where the set screws were hitting. Boot elevators were function after the crash.
                                          I was remembering back to when I was putting this together. Before I had the control rods on, the elevators just "fell" until they hit something - in retrospect, it was probably exactly this that they were hitting. I just looked at mine and do see visible indentations. But I am pretty sure they are leftover building scars - the travel before installing the rods was a lot more than after I installed the rods.

                                          I think this is something to watch for when you are building (you do want the screw-head centered), but doesn't seem like a problem as long as you do that. After a crash you might see deep indentations for the same reason - if the rod pops off at impact, the surface could hit this screw with momentum.

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