Prop Extra 260 Tail Problem

regme40

Member
Hi

I have just started to put together a HK Extra 260. I know but its the first and it won't be too expensive to trash.

Anyway when I dry fitted the horizontal stabiliser it was a bit out. So I just want to float past how I was going to fix it.

What the stabiliser sits on seems a bit thin so rather than sanding it down I'm thinking of sanding the top and pack under the stabiliser.

My next question is I'm assuming that the horizontal stabiliser needs to be horizontal both from when looking from the side and back? It doesn't have a incline when view from the side?

Cheers
 

Tony

Staff member
The first part of that I think would be better explained in a video so we can see what you are talking about. As for the second part, all of my planes (3 Fliton and 1 GreatPlanes) are even and horizontal to the chord of the wing. The main wing and the horizontal stab should be at the same angle. Let us know on the first part.
 

regme40

Member
Hi Tony

Don't have vid, but photos. I have also put measurements on the photos.

So you can see that at the rear of the plane its 50mm on both sides and 56 to 57mm as you move to the front.IMG_2207w.jpgIMG_2209w.jpgIMG_2211w.jpgIMG_2212w.jpg

- - - Updated - - -

Hi Tony

Don't have vid, but photos. I have also put measurements on the photos.

So you can see that at the rear of the plane its 50mm on both sides and 56 to 57mm as you move to the front.IMG_2207w.jpgIMG_2209w.jpgIMG_2211w.jpgIMG_2212w.jpg

IMG_2207w.jpg

IMG_2209w.jpg

IMG_2211w.jpg

IMG_2212w.jpg
 

RandyDSok

Well-Known Member
You don't measure the angle of incidence of the horizontal stab to the fuse... it is compared to the wing and even then there will likely be a few degrees of difference between those.

Tony already mentioned the important aspect you need to concern yourself with... you line up the stab with the wing and it should be parallel with each other... If one side or the other needs a slight shim to make it parallel you can use cardboard to shim it with and the cardboard will soak up the CA glue you use to mount the stab with.

Leave the angle of incidence's you find on the wings and the stab where the designer had made them.
 

Tony

Staff member
Okay, I get what you are saying. Don't worry about that. That is just the bottom of the fuse going down as you go forward. Just make sure when you put the stab in before you epoxy it, measure from the corner of the stab to the corner of the wing on both sides and make sure the wing and stab are parallel to each other. Once that is done, mark the stab, use a soldering iron to cut the covering and epoxy it in place. Should be a great build and I can't wait to see it complete. Let us know if there are any other issues.

And we would really like to see some pics of the rest of the plane including detailed pics of the motor mount and inside the fuse.
 

RandyDSok

Well-Known Member
Based on the color scheme... it appears to be this one HobbyKing R/C Hobby Store : Extra-260 EP 49inch ARF

It is designed as a sport flyer and not a 3D machine though some do a tad bit of 3D with it... Considering the flat tail surfaces ( like any plane that has them ), it isn't recommended to fly it very fast as it can lead to flutter on the surfaces unless you take additional steps such as sealing the hinge lines... Metal gears are recommended for at least the tail surfaces, I still prefer them all around personally. A number of folks have gotten away with using a nylon geared servo such as the HXT-900 that HK sells, but many of them have also had them break under the stress also... so it's better to safe than sorry.
 

regme40

Member
I'll take those points into account.

Rdsok, yes it a HK Extra 260. I got the Corona Digital Servo which is metal gearing for all the control surfaces.

I was thinking about puting tape on the hinge lines HK have this "High strength fiber tape 15mm x 50mtr" what are your thoughts on this?

I thought the Exta 260 could do 3D, maybe the HK version is different to the others out there.

Cheers
 

RandyDSok

Well-Known Member
When sealing a hinge line it isn't used to make it stronger, it is only used to seal it so air doesn't get through and cause turbulance which can result in flutter as I mentioned. You also want to avoid something that would make the hinge line bind more... most of the times I've read about someone doing it, they use covering ( like monokote or ultracote etc ) to seal it with. To help avoid causing additional binding... hinge up the control surface as you would normally ( if using CA, don't use too much as this will also cause binding )... Then cut some strips of covering the length you need and fold it in half so you can get as much of it as possible into the hinge line... then stick it down with a covering iron. I bought a roll of clear just for this purpose so it doesn't cover up the design of the original scheme.

The original full size ( as well as scaled versions ) Extra's, Edge's and other similar planes were not designed for 3D... they are designed for acrobatic flight. Model designers then took these designs and made alterations such as enlarging the control surfaces to aid in 3D stunts and maneuvers. I know that HK didn't market the one you have as a 3D model and if you compare it to one that is properly designed for it... you'll notice that the control surfaces are significantly larger.
 

Tony

Staff member
I would not tape the hinges, I would use CA hinges on it. That is what I have on all of my planes and I will never look back with something 50" and smaller. Now larger than that, I will use plastic pocket hinges.
 

regme40

Member
I have changed the hinges to the plactic ones rather than the paper ones supplied and will be trying to make the gap between the wing and aileron as small as possible, I just thought placing a layer of tape along the hinge line would stop the flutter.

Just with the tail alignment, would you do the measuring with the plane on a flat surface or lift it off the ground on its C of G so th wings are level. Would that mean I would have to finish the plane (install motor, servos, etc) to get the right C of G or can I do it with just the body and wings only?

I hope that made sense. Once I get better I'll look into a 3D version

Cheers
 

Tony

Staff member
You don't need to set it on the CoG. Just bolt the wings on and measure them out to the elevator. That is the way I did it on all of mine. And as for flutter, I have never had an issue with my planes but I don't fly full speed very much either. If you get flutter, just back off to 1/2 throttle and it will go away.
 

RandyDSok

Well-Known Member
On the hinge line... making them as small as you can may also be an issue... yes you do want it as small as possible but at the same time you don't want to limit the travel that the surface can move. So prefit the control surface then move it in both directions for more a bit than the instructions say for max travel if it is mentioned. If they aren't listed... On the rudder, get it to go the limit the elevator cutouts allow and probably don't go much more than 45 degrees on the others at the most. While those are typical "3D" amounts and you aren't likely to use that amount of travel... they won't limit you either and will help ensure you don't have binding.
 

Tony

Staff member
This is just me, but I make sure my controls can move 55 degrees. That way I know there will be no binding. But as stated, you will very rarely move the surface that much unless you are doing a hard snap or trying to hover or something of the sorts. I know I have had to do some stick banging on mine once in a while. Once Randy was standing there when the wind tried to push me into the ground lol. Full up on the elevator just to save it lmao. Sucked and it is on video.
 

regme40

Member
Well got the stabiliser last night, thanks for the all the advise.

Hope to get all the control surfaces on this weekend and maybe in the air depending on the weather.
 

regme40

Member
Hi

Another question relating to the tail, I have read that on landings the tail wheel can exert pressure if attached to the rudder. I know the main part is attached to the body of the plane and a length of wire is attached to the rudder.

Does it really make a difference to have a steerable tail wheel. I would have thought that with that size rudder and power from the motor it would just spin around?

Cheers
 

RandyDSok

Well-Known Member
The effect of the pressure of the tail wheel on the rudder is taken into account in the design itself. I've never seen a rudder damaged by the tail wheel though I've see several tail wheels that were not attached well and came off. In fact, it is pretty common since the glue doesn't have a lot to hold on too.

It is so much easier to taxi with a stearable tail wheel than not... you have little to no fine control without a stearable gear.

- - - Updated - - -

PS... If I hear a person trying to place blame on damage to any part, the rudder in this case... I question it and assume they are really the one at fault and they are just trying to shift the blame elsewhere. In the scenerio you are asking about, the blame would be with either poor assembly with the rudder not being glued/attached properly OR the landing was done poorly and they landed hard or ran into something etc.
 

Tony

Staff member
I have had both of what rdsok has stated. On a landing my hinges broke because they were of crap quality and my rudder came flying off. I have also had a tail wheel come off on me but as stated there is not a lot for the epoxy to grab onto. But the plane I'm talking about was not designed for a tail wheel and I mounted it directly to teh rudder. However my Edge has a factory wheel with the small wire like yours, and the main pressure will go to the fuse and not the rudder. I will not fly a plane that doesn't have a tail wheel.
 
Top Bottom