Linkage / Hardware Questions
 

I'm looking for quality hardware for my new plane. I've been looking long and hard at the MK stuff.

I'm building a Creek Hobbies (1/4 scale) Sukhoi. I've already got the high torque servos on the way.
I don't ever want to run the risk of losing a plane due to crappy hardware (as most kits are shipped with).

I would be making 5 relatively short runs, from servos to surfaces.
I was thinking of the these:
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P/R Set 24" x 5/32" Carbon Rods/Titanium 4-40
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It appears that these kits come with 2 PRs and 4 fittings. Obviously I'll pick up more fittings as I don't need two long PRs but many short ones.

I'm looking at getting the MK control horns. I also would like to know what sizes you would recommend for ailerons, elevators, and rudder. The two sizes I am considering are 1" and 3/4".

http://centralhobbies.com/miscellaneous/cntrlhrn2.html


I'll finish it all out with what seems to be the expensive parts; the clevises and adjusters w/bearings. I had my doubts but it sounds like they will probably outlast the plane. They can always be used over.....

http://centralhobbies.com/miscellaneous/cntrlhrn.html

Anyway, the BIG question is this. I read on the centralhobbies website the install instructions for the control horns.

http://centralhobbies.com/bestbuilt/...hornsinst.html

The author suggested quite a lengthy process for cutting up the control surface to mount a dowel for these control horns. I do not have a drill press or many of the other luxuries that the author does.

My plane's control surfaces aren't that thick (save the ailerons).
Is is totally necessary to have a Dowel in the control surface for a 1.20 size model? Can these clevises just mount through the surface itself, with perhaps some thin CA to harden the mount point? (Epoxy for foam) Maybe a lightply insert on top and bottom of the hole?

The kit came with the regular Nylon control horns (two mini screws to hold in place). I want survivability but I want to have something fairly user friendly as well. At this point it seems that the MK control horns may be more work than just taking the chance with another form of standard control horn.


EDIT!
I just realized that I probably won't need any CF rods. The distances from the servo to the surfaces are pretty short... Therefore I doubt that I'll even need to use any CF if I can find a stiff enough 4-40 threaded shaft.

Anyone know who has the strongest, lightest threaded shafts. I would prefer the whole thing be threaded as it would be easier with the connectors I plan to use (above). I still need to know about the mounting of the control horns.


Thanks for your time.

Control Rods
 

Get a Rod-Chuck and make the pushrods from 1/8" welding rod.
"All Thread" is a very poor choice as it has a tendency to be more flexible and break under load.

EXCAP232

Linkage / Hardware Questions
 

That sounds like a very good idea.

http://www.rodchuck.com/

I'll check it out. It makes sense and sounds safer than what I was thinking.

Control horn question anyone? Push Rods seem to be taken care of.

Thanks!

Linkage / Hardware Questions
 

You should look into the Hangar 9 Titanium pro-links for pushrods. I'm using them on my new plane and they are great. They allow for length adjustments that you can't get with anything else (unless you make your own, and put left-hand threads on one end).

As for the control horns, I have used dowels before, but recently started just using a ply plate recessed into both sides of the surface. Easier to do and shouldn't sacrifice strength (I haven't finished the plane yet so I can't say for sure, but I really don't think it will fail).

Ben

Linkage / Hardware Questions
 

That's looking like what I am goingg to do as long as noone advises against it.

I was thinking that the light ply would probably be a safe enough solution.

Thanks for the input on the rods as well. I appreciate it.

Linkage / Hardware Questions
 

Lite ply might not be quite enough. For a 1/4 scale I'd probably use 1/8 aircraft ply on each side. I used 1/4 aircraft ply on the plane in the photo (it's a 1/3 scale extra). Are your control surfaces sheeted foam?

Ben

Horns
 

I used the Alum. horns with CF rods and ball joints on both ends. Zero slop. In fact, the small amount of slop that was in the gear-train, really showed itself.

This is small 3D plane, so 2-56 CF rods and ball joints were used. You may want to look into 4-40's.

I am finishing up another plane, using the Hanger 9 titainium rods. The CF are about half the weight of the H9's.

MK also makes some off set control horns that work very well.

Linkage / Hardware Questions
 

bdphil, I was thinking 1/8" ply when I posted that.

I didn't mean to confuse with the term lite ply. I guess that has a certain measurement or is a certain type of wood that is different to the ply you mentioned?

Yes, the ailerons are sheeted foam. The other surfaces are regular wood and seem like they are built rather strong. I'm thinking of recessing the ply as noted above.

I'm guessing that the sheeted foam is not near as strong as the other surfaces and that there is something I should do (more than the ply) to ensure a strong connection?


YNOT, that pic looks pretty sweet. I've heard that ball joints aren't really the way to go on the larger birds (for control surfaces). I'm sure that is a hot topic of debate as I have seen it a few times searching the boards for answers. I would have to say that it's a matter of opinion. Personally I think it all matters on the situation and the hardware used. Those titanium rods seem like they are very good. I like the idea of adjusting them without removing the clevis. I may use them on this bird eventually but for now I like the freedom in the method posted about the welding rods. I can make them the perfect length and not really have to guess on what H9 rods to order. I like them but to tell the truth, haven't measured the actual distances to the surfaces. I'd hate to order a bunch @ 6 or 7 bucks a pop to have them be slightly long or short. Granted I could use the existing rods and make them the right size then order based on the length of the rods that I will not be using but I haven't gotten the servos or control horns yet..

I liked the look of the offset MKs as well. I just figured I'd keep this one as simple as possible this time around.

I appreciate the input! This board is the best when you have a question and the knowledge base is superb!

Thanks

Nelson hardware
 

Hi bdphil,

What Extra is that? I fly a RadioCraft 35% :D

Do yourself a favor and add a 4-40 jamb nut to the titanium link and jamb against the standard thread clevis to keep the link from rotating (I know, they feel nice and tight...). Also call Nelson Hobbies and have him send you some more of those 4-40 lock-nuts and add them to the "Rocket City" side of your linkage. Use a longer bolt, through the square nut and then the lock-nut.

I know, I'm paranoid, but it doesn't hurt a thing :rolleyes:

Later,

Willem

Linkage / Hardware Questions
 

Swivel ball links not good for big bird control surfacesWHAAAAT!!!
Just about every 35-40% plane I have seen or built has the Rocket City set up posted by bdphil.It just doesn't get any better than that,servo arms tend to vary between Nelson or aluminum.I can promise there will be no slop,and super smooth precision in the linkage,any slop will be in the gear train.I also use this sety up on 25% planes,a little overkill,maybe,but dependable absolutly.
Mike

Linkage / Hardware Questions
 

willembad,

The extra in the pic is a 32% 3W extra.

I thought of the jam nut idea, I use them on any setup with clevises (plastic or metal). As for the square nuts on the rocket city horns, shouldn't that have been thought of by the manufacturer by now? I mean that's an obvious flaw in the design. So if anyone with friends in high places is reading this: instead of molding a square hole in the horn, mold a hex hole and provide a nyloc nut. I'll be looking for this modification on later models.

Ben

Linkage / Hardware Questions
 

lv2, I would agree with what you said. Look at the two pictures posted in this thread. I was addressing YNOT's linkage as the "swivel/Ball" linkage.

To me it APPEARS that his linkage is the kind mostly seen on a throttle (metal ball with a plastic socket around it). I cannot be 100% as I can't see the back side.

http://rcuniverse.com/attachment.php?s=&postid=528198

All I said was that I had seen it debated a few different times on this board. I was careful not to make the statement that any linkage was or wasn't good for a certain application.