Dave trimmer

My TF p47 is supposed to move 3/8" up and then down 3/8" my aileron has 1/8" of slop. Where the Bellcrank has a slight to big of a hole where the linkage to the aileron comes to the bell crank. I have the kind of linkage where you bend the control rod and a plastic piece holds it on the horn. what can I do to make it a snug fit?

Thanks, Dave Trimmer

opjose

To eliminate the slop I usually just replace the control horn itself.

bruce88123

Use a linkage with a clevis. Use a fresh servo arm that hasn't been drilled or wallowed out. Even consider 4-40 hardware for a plane of this size and calibre, less flexing. Time to move up in the world and away from cheap plastic keepers on SOME things.

Dave trimmer

Well I guess I just had a brain fart, I just put tape around the rod for a nice fit.

thanks.

Dr1Driver

Well I guess I just had a brain fart, I just put tape around the rod for a nice fit.

I sincerely hope you're joking.

You've found out that a little slop in the linkage turns into a lot of slop at the surface. replace the bellcrank. If you're using 2-56 linkage, drill the holes in the bellcrank with a #50 or #51 drill bit. The wire will be tight in the hole, but that's what you want. You CAN swap out for 4-40 linkage, but it's not really necessary on this plane. If you don't drill the proper size hole for 4-40 (#44), you'll have the same problem.

Dr.1

j.duncker

My Feedback: (2)

Keep your eye on the slop. Even 1/8th slop can give you flutter. Flutter will usually destroy a model in seconds.

bruce88123

I was giving him credit for being able to drill the right size holes. On the other hand, a lot of modelers have a terrible selection of drill bits to choose from and may as well use a hammer and nail to make the hole.(Not a recommendation) Arm holes for Z-bends and L-bends are notoriously oversized because of the difficulty getting the curved portion through the hole.

opjose

As Dr1Driver was alluding to, putting tape around the rod doesn't work.

The constant movement will wear through the tape causing flutter at the most inopportune time.

Dr1Driver

I just gotta ask...you don't know how to fix this problem correctly and you're building a .60 size warbird to fly??? Maybe you're in over your head a little?

Dr.1

Dave trimmer

I did not build this. I Have great flying skills but unfortunatly I lost my job (aparently I didn't call early enough this year) and my dad has no work for me. I would do it right but am almost at the point where I cant buy a bus ticket to purchase a new Bellcrank. and I think I'm done borowing money. I was hoping for a suggestion about using something in my work shop.

Please take no offence to this but do not like it when people I have never met question my abilities. Every day each of us will experience something we have no Idea what were doing. I dislike it when people question my flying abilities. I understand now that It is dumb of me to have thought of using tape, but I have worked hard at making this model mine and must do it RIGHT but I want to see It go, I have 4 planes, 1 for 8 months waiting to fly.

I like to fly more than building and I want to do it right but I want a quick fix that will work!

No hard feelings, Dave trimmer

bruce88123

http://manuals.hobbico.com/top/topa0135-manual-v2_1.pdf

This should be the manual for your plane. Maybe it will help give you some ideas. It's built different than I expected if built per this manual.

Dave trimmer

heres a pic, the problem is the rod connescted to the aileron. And there is a plasitc piece that goes over the Z bend

bruce88123

OK, it's a bellcrank. Is all or most of the slop coming from where the pushrod attaches to the bellcrank?

Dave trimmer

All of it, not much just about 1/8" measured on the aileron movement.

bruce88123

If you have the room (and the money) I'd put an adjustable clevis on the bellcrank end of the pushrod and a solder clevis on the aileron end. A new bellcrank may also be needed.

If you replace one bellcrank it must match the other side
Tower numbers: LXD938, LXDMK4, LXK109 For some reason no dimensions are given.

You'll have to make the decision.

overbored77

My Feedback: (11)

Dave, I have forund that using supplied hardware or the cheaper stuff always causes slop on my planes. I use captured
ball ends on the servo horns for all my pushrods. http://www2.towerhobbies.com/cgi-bin...?&I=LXD907&P=0
I have no slop and if you change the nut that comes with these to a locknut maintenance is minimal.

daveopam

My Feedback: (9)

Dave just use the next hole in on the bellcrank. Just be sure and do the same on the other side. This will give you a little less throw. If that is a problem just go in one hole on the other side of the bellcrank where the clevis is also.

David

j.duncker

My Feedback: (2)

NOT A GOOD IDEA

This will make the slop worse. Go out on the bellcrank and out on the aileron horn if at all possible.

Dave single servo aileron setups using bellcranks are notorious for slop. I will repeat my warning about flutter but if the slop is 1/8th at the T.E. and the ailerons feel solid after the slop is taken up AND YOU INTEND TO FLY AT SCALE SPEEDS AVOIDING FULL POWER DIVES then I would give it a go at a deserted air strip well away from people. But if you hear a buzz in the air slow down and land as quickly as possible.

To see what happens if ailerons flutter watch this.


http://www.voy-tech.net/friendsrides...afalecrash.wmv

CGRetired

My Feedback: (1)

Jeez, Chris.. you actually put Futaba in your signature?


Every time you make an angle change like that, using belcranks (now I know that this is the way it was designed by the manufacturer and cannot be helped), you will induce some sort of error. In this case, you will have four connections to deal with: one at the servo, two at the belcrank, and one at the control horn. The best way to illeviate this slop is to follow what was mentioned above by making sure all connections are snug.

Another error.. or slop.. is with the way the belcrank is mounted. If that screw setup at the center of the 90 degree belcrank is not tight, it will wobble, inducing more slop. This will be a tad more difficult to correct unless the hardware is new, fresh, and fits exactly right.

One method to correct this, to eliminate this slop, would be to remove this belcrank setup, run a servo extension and build a servo mount in the wing to directly control the aileron. The servo can be mounted on the side and a little ingenuity can certainly go a long way to make up the servo tray and make it invisible and work better than a belcrank setup could ever work.

DS.

bruce88123

Hey guys, don't forget the part where he said he has virtually NO money to work with here.[]

daveopam

My Feedback: (9)

I agree moving the rods in does reduce the mechanical advantage of the setup. But, better that then use the oversize holes he is using right now. If the slop is at the pivot point then my bad. This will make things worse. I was only suggesting a band aid to get him flying until he had the funds to fix it right.

David

scratchonly

Try a piece of heat shrink tubing over the bellcrank arm, with a small hole punched in the tubing; keep an eye on things between flights.