Originally Posted by mdauth

I was able to go out yesterday evening with the new arm on the servo, it did improve but still need up trim at high speed not as much though, see pic of the elevator at full throttle. I'm still getting movement on my elevator in neutral position, because the servo arm and the horn are not parallel I'm getting some twisting motion on the arm and servo so I can force the elevator up or down, I'm thinking that at high speed that movement is giving down thrust. Look at the second picture of my setup I bent my rod so the ball link can be parallel to the arm and horn, I guess that wasn't good, should I shim the servo so the arm and horn get more parallel?? I'm pretty sure the problems comes from there.

I did notice on your rudder hinge that you did not iron a strip of covering to seal the gap. Did you also omit that on your elevators? I honestly don't know if that could have anything to do with your symptoms, but maybe. The way I understand that sealing the gap works is that it prevents the higher pressure air on the deflected side of the control surface to bleed through the hinge gap to the other side. I had always assumed not sealing the hinge would just reduce the effectiveness of the control surface, but it might affect the control surface's ability to trim the plane too. Just a thought.

Originally Posted by Neil_SC

A guy on the 71" Slick thread had his stock Hitec arm come off after the screw backed out.

Did he have lock-tite on the screw? All I'm using with my Savox servos is the stock screw (metal on metal) with blue lock-tite.

Originally Posted by Lomchevac

Also make sure there are not any mixes set for throttle to elevator. Just a thought

On the 8fg you can see all servo movements and I checked when I move the throttle no other servo moves. Here I changed the rod, now need to test. I still have a bit of movement when I force by hand but I compared it to my Slick and it's the same.

Originally Posted by Neil_SC

I would definitely not bend the control rod that way. There are ball links on each end so they can easily accommodate the geometry without bending the rod. Now that the rod is bent, it can be bent now by the forces on the elevator and servo in flight. And if you are seeing some twisting of the servo arm, I would switch to a metal arm. In fact, at this size plane and cost, it's worth the extra security of a metal servo arm that has a secondary mechanism to grip the servo spline, like the Hangar 9 and SWB arms. A guy on the 71" Slick thread had his stock Hitec arm come off after the screw backed out. With the Hangar 9 and SWB arms, they have a bolt that when tightened will squeeze the arm around the servo spline. So even if you lost the main screw, it is still gripping the spline and won't come off. Plus the metal arms allow no twisting.

I had the Aluminum Arm buy Seacraft, I took it off just to test, It's back on if you look at my last pic. but I did order new ones with the set screw on the side for security after reading that post on the 71" Slick.

Originally Posted by Neil_SC

I did notice on your rudder hinge that you did not iron a strip of covering to seal the gap. Did you also omit that on your elevators? I honestly don't know if that could have anything to do with your symptoms, but maybe. The way I understand that sealing the gap works is that it prevents the higher pressure air on the deflected side of the control surface to bleed through the hinge gap to the other side. I had always assumed not sealing the hinge would just reduce the effectiveness of the control surface, but it might affect the control surface's ability to trim the plane too. Just a thought.

Thanks for noticing that, I completely forgot to iron a strip on the ruder and elevator, will do it before I try it again.

Hey guys,

I just had to repaint my cowl on my Edge (Silver Scheme), does anyone know of any paint that matches the black stripes. It isn't just black it has a metal flake in it. I used Rustoleum Safety Red on the cowl and it is almost an exact match.

As has been said, straighten the rod, and change the servo arm to an aluminum one, then space the ball link out about the thickness of an M2 nut (use a longer screw if needed)... Also, looks like a Savox servo...which one?

And...while sealing the hinge gap is a good idea if done correctly, if done incorrectly, it can cause more problems than it is worth....

SteveT.

Originally Posted by SteveT.

As has been said, straighten the rod, and change the servo arm to an aluminum one, then space the ball link out about the thickness of an M2 nut (use a longer screw if needed)... Also, looks like a Savox servo...which one?

And...while sealing the hinge gap is a good idea if done correctly, if done incorrectly, it can cause more problems than it is worth....

SteveT.

What do mean by doing it incorrectly, meaning making sure it's iron properly?? If not it can come off and jam it's self somewhere you don't want it to be!!! Savox 1258tg

Originally Posted by mdauth

Thanks for noticing that, I completely forgot to iron a strip on the ruder and elevator, will do it before I try it again.

Gap is sealed, I should take a couple pics of the plane and you guy's can let me know what else could be wrong!!! By the way I checked the manual quickly and they did not mention sealing rudder and elevator gaps?? I guess it's known to do it.

Originally Posted by mdauth

What do mean by doing it incorrectly, meaning making sure it's iron properly?? If not it can come off and jam it's self somewhere you don't want it to be!!! Savox 1258tg

Sealing the gap on a plane this size is really not mandatory, but if done properly, doesn't hurt...

Sealing the hinge gap is not just a matter of ironing a strip in, if you get it too tight, you won't get full deflection, if too loose, it can bunch up, again causing a loss of full deflection. I use a strip of Ultracote, cut to the needed length, and if the plane has Robart type hinges (which the 74" has), I cut away the area where it will go over the hinges. Deflect the surface as far as it will go, then iron the strip on, making sure the openings in the covering go over the hinges, and also making sure there are no wrinkles, and it is all ironed down. You really only need to do one side, though I have been known to do both....

SteveT.

I've been out of town on vacation for several days now and out of touch...sorry I missed out on the chance to help diagnose a gas 74 with setup trouble....

I think you're getting VERY close to having this handled....I believe that the ability to "...force the elevator up or down..." due to the "non-straight" rod is most of the problem....

1) don't adjust the thrust angle away from "stock"

2) servos should always be able to FIRMLY hold the surfaces at any position you want..against "more-than-reasonable" force....if not, find the trouble and fix it.

Precise servo-surface connection and control are CRITICAL.

3) hinge-gap sealing won't affect the trim issue you describe....but properly sealed gaps will reduce the risk of "flutter", will make your servo geartrain last longer...and will add a bit of "precise-feel"...just a bit...most of us won't notice this feel...only the reduced flutter risk and longer gear life...and on a plane this small...there are not big gains on either of those....


4) Thanks to SteveT...a SERIOUS E-power guy for assisting on the diagnosis of this gas 74...with good advice all around.....

5) I agree with Skippy...both of us have had 2 different gas power plants (and I've also had a can) on our 74's.....and both use pull-pull....no weird battery placement...and our CG's are just fine...you really cannot mess up the CG on a 74 using standard gas engines and battery placement....so I'm glad you already ruled that out.

Report back after you get more flights on it without the elevator slop...

Originally Posted by Bivens

I've been out of town on vacation for several days now and out of touch...sorry I missed out on the chance to help diagnose a gas 74 with setup trouble....

I think you're getting VERY close to having this handled....I believe that the ability to "...force the elevator up or down..." due to the "non-straight" rod is most of the problem....

1) don't adjust the thrust angle away from "stock"

2) servos should always be able to FIRMLY hold the surfaces at any position you want..against "more-than-reasonable" force....if not, find the trouble and fix it.

Precise servo-surface connection and control are CRITICAL.

3) hinge-gap sealing won't affect the trim issue you describe....but properly sealed gaps will reduce the risk of "flutter", will make your servo geartrain last longer...and will add a bit of "precise-feel"...just a bit...most of us won't notice this feel...only the reduced flutter risk and longer gear life...and on a plane this small...there are not big gains on either of those....


4) Thanks to SteveT...a SERIOUS E-power guy for assisting on the diagnosis of this gas 74...with good advice all around.....

5) I agree with Skippy...both of us have had 2 different gas power plants (and I've also had a can) on our 74's.....and both use pull-pull....no weird battery placement...and our CG's are just fine...you really cannot mess up the CG on a 74 using standard gas engines and battery placement....so I'm glad you already ruled that out.

Report back after you get more flights on it without the elevator slop...

Thanks for the info, yes everyone has been a great help, I'm pretty sure that the problem should be resolved, I should be able to got out this evening if the weather holds up.

Mike

Originally Posted by Bivens

I've been out of town on vacation for several days now and out of touch...sorry I missed out on the chance to help diagnose a gas 74 with setup trouble....

I think you're getting VERY close to having this handled....I believe that the ability to "...force the elevator up or down..." due to the "non-straight" rod is most of the problem....

1) don't adjust the thrust angle away from "stock"

2) servos should always be able to FIRMLY hold the surfaces at any position you want..against "more-than-reasonable" force....if not, find the trouble and fix it.

Precise servo-surface connection and control are CRITICAL.

3) hinge-gap sealing won't affect the trim issue you describe....but properly sealed gaps will reduce the risk of "flutter", will make your servo geartrain last longer...and will add a bit of "precise-feel"...just a bit...most of us won't notice this feel...only the reduced flutter risk and longer gear life...and on a plane this small...there are not big gains on either of those....


4) Thanks to SteveT...a SERIOUS E-power guy for assisting on the diagnosis of this gas 74...with good advice all around.....

5) I agree with Skippy...both of us have had 2 different gas power plants (and I've also had a can) on our 74's.....and both use pull-pull....no weird battery placement...and our CG's are just fine...you really cannot mess up the CG on a 74 using standard gas engines and battery placement....so I'm glad you already ruled that out.

Report back after you get more flights on it without the elevator slop...

Thanks Bivens.... I just wish I could have actually figured out the problem.....it bothers me when there is a problem and I can't figure it out.....

SteveT.

Originally Posted by SteveT.

Thanks Bivens.... I just wish I could have actually figured out the problem.....it bothers me when there is a problem and I can't figure it out.....

SteveT.

Hey Steve, don't be so hard on yourself, It's kind of hard when you don't have all the elements in front of you. I decided to change the servo also, I felt that it wasn't holding well when forcing the elevator I was able to move up and down with enough tension, seems better now. Nice thing about this is with all this testing I'm breaking in my motor, will be ready to change the prop soon and push this thing.

Hi Guys,

Just a quick question as im starting to get confused. I have been having an issue with the Hacker a50-12L in my 74 edge. if i quickly advance the throttle i get a strange noise and the motor cuts out? is this a timing issue in the ESC or am i doing something else wrong? this stuff is all different for me as i am a heli guy that just got bit by the 3d plane bug.

Thanks
Matt