Fishin Geezer

I've just begun building my kit and already have questions and I know I'll have more. If the moderators allow, maybe we can keep this thread open for a while to accumulate questions (and hopefully answers) on this build. I invite anyone with questions on this build (and even the US 40) to post them here so we can all learn together.

1. Hinge instructions are confusing. Inst. book (pg. 8) says "one piece molded polypropylene hinges are supplied. Also, heavy duty hinges should be used on the rudder if you are building a taildragger (which I plan to do).
The plans seem to call for all nylon hinges with large hinges (not heavy duty) on the rudder.
The kit is actually supplied with a 2" X 9" piece of unidentified hinge material and intructions to cut it into 24 pieces and apparently treat it as CA hinge material.

So, what do I really have and what should I do about hinges???

2. I bought the other tail gear that MinnFlyer talked about but have decided to use the gear provided in the kit.
So, does the "nylon tail gear bearing" get glued into the rudder or does it get turned forward and get glued into the fuselage?? (I don't understand its function).

That's all for now. More questions later, I'm sure. Thanks for any help.
Frank

MinnFlyer

My Feedback: (4)

Frank, use the CA hinges. They work fine. HOWEVER...

If you use the stock tail wheel bracket (Which I do not recommend) You may want to use better hinges on the rudder.

But I strongly advise you to use a different tail wheel bracket.

I really liked the stock bracket at first because it was so clean looking, but it has two fatal flaws:

1) It puts all of the weight (Including bounces) on the rudder and rudder hinges. A bad landing can easily mean a big repair job.

2) If the nylon bracket breaks or comes loose (Which it will), you can't get at it without removing the rudder.

BTW, the nylon bracket goes in the Fuse side.

Fishin Geezer

Thanks very much, Mike. I get your point about how the provided tailgear transfers all the load directly to the rudder hinges. I hadn't seen that. And I'll use the provided CA hinge material.
I'll take another look at the 2868 and 2878 assemblies. My problem is that as a total beginner (one kit behind me) I've never seen these items in service and haven't a clue how to install them. As replacement items they don't come with any instructions. The appeal of the kit-provided assembly was that I could see how to install it (except for the tail gear bearing).
Any ideas where I might find guidance on using the 2868 or 2878??

Frank

airbusdrvr

One thought about the CA hinges. If they are the kind that are plastic with fabric outer layer, consider using present day CA hinges like http://www3.towerhobbies.com/cgi-bin...&I=LXK110&P=ML . A friend at my club used the CA hinges that came in an older kit that had the plastic layer with the outer fabric layer and the the cloth layer separated from the plastic inner layer causing the aileron to separate in flight. I found these older type hinges in an older kit I was building and substituted the ones above. They are not layered type hinges and should be used.

Fishin Geezer

Thanks, airbusdrvr. This kit is relatively new, released by GP just a few months ago. So the CA hinge material should certainly be of the modern variety.

My concern is now focused on the 20 year old kit I finished recently (SIG Kadet MK II). It's CA hinges were definately the older material you described. OH well, nothing to do now except wait and see. Incidentally, it flew for the first time yesterday. Too windy for me, so the club instructor flew it. Just about perfect!! Took off, trimmed very nicely, did rolls and loops, straight and level, and landed in one piece. I just hope the hinges last long enough for me to get a few flights of my own!!

MinnFlyer

My Feedback: (4)

The only thing you'll need to do to use the other tailwheel is:

When it comes time to close up the fuse bottom with 3/32" balsa, use a piece of ply for the aft section, and add a small block of balsa (Optional) for the nylon pivot.

Fishin Geezer

Thanks, Mike. Very nice drawing. Wish I knew how to do that!!

So, when using the "other" assembly, is it not connected to the rudder and therefore not a "steering" tailwheel? Is it rigidly aligned with the fuse centerline and therefore just follows? Pretty complicated, I guess!

Frank

airbusdrvr

Fishin Geezer, go to this link in the kit building forum, http://www.rcuniverse.com/forum/m_6775526/tm.htm , and look at the tail wheel picture in post #20. I just finished a plane similar to yours and used a Sullivan tailwheel. You can find it here, http://www3.towerhobbies.com/cgi-bin...&I=LXFV47&P=SM . It is a very simple installation and puts no loads on the rudder. After the build whether using a nose gear or tail wheel one always has to make minor adjustments to have the plane taxi straight. The Sullivan tail wheel only requires slightly bending a spring either left or right to correct the taxi line. Or better still with the picture, I'll attach it in this post. See below.

MinnFlyer

My Feedback: (4)

Sorry, i sould have finished the picture. The tail wheel assembly has a tiller that attaches to the rudder

airbusdrvr

MinnFlyer, what brand is that tailwheel? I'm curious how it steers as the pivot point is forward of the rudder hinge line. It would seem the steering arm attached to the rudder bottom would be trying to move the pivot point left and right instead of rotating the tail wheel assembly. But as is usually the case, there is probably something I'm missing when looking at the diagram. Thanks

MinnFlyer

My Feedback: (4)

The tail wheel is made by Great Planes:

http://www3.towerhobbies.com/cgi-bin...?&I=LXLLB9&P=7

And I'm not sure what you are seeing (Or not seeing, but it steers just fine. Here's a top view

airbusdrvr

I pulled up the Yak 54 assembly instructions from the Tower site and see that the pivot point is just forward of the aft end of the fuse(just forward of the rudder hinge line). Same set up as the Sullivan but the pivot point is just a bit more forward. Shouldn't make a lot of difference. Initially it seemed from your picture above that the pivot point was more forward than it actually would be. Same design, different manufacturer. Either should work well.

MinnFlyer

My Feedback: (4)

This same setup is used in the GP Skybolt ARF and I just love it.

Unfortunately, the exact one used on the Skybolt is not available. The one that IS available is slightly bigger, but usable

Fishin Geezer

Thanks Mike. It's so good of you to take the time to explain all the details to me. I think I understand now and I hope others are also benefitting from your patience.

airbusdriver: Thanks to you also. I'll get one of those Sullivan assemblies, just for comparison. Part of the explanation of the Great Planes case may be that the connection at the rudder bottom is a "sliding" connection. If the radius changes while steering (I'm not sure), it just causes a small change at that connection. Also, at this point, I'm assuming the pin embedded in the rudder bottom is not glued in and is allowed to rotate if required.
Again, thanks for all the help.

Frank

MinnFlyer

My Feedback: (4)

No, the pin does not rotate, but the hole is slightly larger than the wire, and the tiller wire is flexible. The difference in angle is also so slight that it really doesn't matter.

Fishin Geezer

I got it, Mike. Thanks again!!

Frank

mikenlapaz

This is some useful ideas on the use of this tailgear as well.
http://www.rcuniverse.com/forum/m_32...timate/tm.htm#

I'm in the process of installing one on a mid star 40. I think I may have errored in installing the block and drilling for the mount bushing. I put the hole is 2" forward of rudder hinge.
This same gear is on the GP Ultimate 160and the GP 25% Yak54 1.6ARF None of the instructions specify the distance forward of hinge line as they have predrilled.

Moving the tiller wire slide guide on the rudder aft will help increase the arc of wheel turn.

Any guidelines on how much of an arc the tailwheel needs on a 40 size? How far forward can this gear be mounted?

(No, I can not easily install a new interior support block as I put a balsa block over that fuse tail area to accomodate a Robart hinge pin into the fuselage)

I plan on using this same tailgear on my US40 in the future.