newbieT

I'm building my pt-40 and quite happy that the covering is done so I move onto the next steps. I get the landing gear attached and mount the nose gear. Notch all the landing gear wire where instructed and put on the control horn for the nose gear. I begin mounting the engine and get all the screws tight and then take a second to look over everything when I realize the nose control horn hits the remote needle on my engine (mounted vertically). I didn't want to have to notch out the side of the fuse for the needle and decided to mount it that way. Now the plane is covered and now I really don't want to notch it! So I though tof alternatives. The easiest one I came up with was to mount the needle vertically from the bottom of the back plate on the engine (see pics below). Is there anything wrong with this setup? I'm easily able to get at the needle from below the plane, so I see no access troubles. Is there perhaps some problem with having the fuel line drop down and have to return up to the carb?

-Dave

DavidAgar

My Feedback: (108)

From the looks of your pictures, your back plate has been removed and turned. The needle valve should be on the oppisite plane or 180 degrees from where it is now. I would remove the screws that are holding the needle valve bracket in place and install it so that you are adjusting the needle valve from the top of the engine. Hope this helps and good luck, Dave

newbieT

Well, that kind of defeats the purpose. I had it installed that way, but as I said, the nose gear control horn hits the needle valve so I wouldn't be able to turn right! I didn't rotate the back plate, just moved the needle bracket to the bottom screws so it would be out of the way. Behind the engine there isn't much room. Having the control horn there with the needle is really tight. I thought about moving the control horn to the bottom of the fuse (like my old avistar 10 years ago) but that would require drilling more holes and rerouting all that stuff. So, I though to move the needle to the bottom would be easiest. The only thing I wonder about this setup is if there's any problem with the fuel getting to the carb from below the engine?

Here's a picture of what I'm talking about. I put everything back for a mock up. You can also see the trouble I had getting the monokote around that area [sm=spinnyeyes.gif] Ah well, I guess it's not only a trainer for flying, but building and covering too,

So, now that you can see the problem...and the fact that I didn't really want to cut out the side for the needle, there's the dilema. If there's no problem with mounting the needle below the carb, then I have an answer!

Fubar-One

My Feedback: (1)

I have never seen that before. It looks like you have your steering rod routed incorrectly. Generally the steering arm will be UNDER the engine mount. Going top to bottom on the nose gear: Collar, mount, space, mount, second collar, steering arm, coil, wheel. Or some variation of that. ALL planes I have, either kit or ARF have the steering arm below the engine mount.
You need to re-route that sucker! Then the remote needle wont be in the way.
Be sure to fill in the old exit hole.

newbieT

I had considered this, but the I followed the pt-40 instructions to a T. The control horn is supposed to be mounted at the top of the gear (I know, I was surprised as well). I'm still considering remounting below the fuse as you said, but was still curious if this configuration was an option.

So...I cross-post to glow engines since I feel I should clarify my question. I'm more curious if mounting the needle like this would cause problems for the engine. Not really wondering how else I could mount the control horn []

I do appreciate the feedback!

-Dave

DavidAgar

My Feedback: (108)

You may have fuel flow problems. Typically speaking your fuel feeds are all in a line, even with the fuel entry point on the carb. I am still not sure why you are have the needle valve on the bottom of the plane. I would think that adjusting the needle valve would be difficult at best. Your fuel feed from the needle valve into the carb is uphill and this could give you bad engine runs. Good Luck, Dave

newbieT

Dave, having the needle on the bottom of the plane would get it out of the way of the control horn for the nose gear (see the last pic I posted). It was one of the configurations I considered without having to cut into the fuse side...the other options are: 1. moving the control horn below the fuse; 2. inverted needle (as pictured); 3. cutting the fuse side (not considered an option, I don't really want to do it); 4. mounting needle on the side of fuse (don't know if there will still be enough room for me not to burn my fingers while being out of the way of the control horn).

In the glow engines sub-forum someone said it wouldn't cause problems running the engine, but you've confirmed my suspicion that it may be a problem...can any one else confirm it'll be problem or not?

Flypaper 2

How about moving in one hole in the arm and cut off the end the would hit the needle valve. Move in one hole in the servo to get the same throw. I also think that's to much throw. Doesn't take much on a trike gear.

newbieT

This is just a guess (I'm at work so I can't try it). I think even moving in one hole would either hit the needle, or it would be just so tight that I might be dealing with a stuck arm at some point. Especially with all the fuel lines running around that area. The kit's design doesn't accomidate for a remote needle. And as I said, I followed the instructions to a T, up to this point. The default instructions say to notch the fuse by the needle (front, upper corner as if there was no remote needle). I still could do this, but I think the fuel lines around there are going to make me nervous!

Fubar-One

My Feedback: (1)

Bummer!
OK, I see you are using an OS LA engine. That remote needle valve can be completely removed from the engine. You could mount that in the inside of the cheek farther forward out of the way of the steering arm. I had to do this with a .46 LA so I could use a Sullivan anti-vibration mount on a camera plane I was messing with.
Also, what was said about minimal steering throw is true. You dont want very much movement or the plane will be a nightmare to steer during takeoffs and landings. Been there done that.
I would see about minimizing the throw on the arm before removing the needle valve assembly.
Being able to U-Turn in the pits isnt a good thing anyway!

DavidAgar

My Feedback: (108)

In looking at your photo, I see what you are saying. I do agree with the fact that the nose wheel needs only a real small ammount of movement so that is one goal. I can also see the motor can slide out a little more on the mount, which might give you another smidge of room. I beleive the real problem is the fact the PT 40 was designed years ago and remote needle valves were not yet invented. My son and some of his buddies are building the PT 40 as we speak. I just looked through the book and the engines shown have needle valves on the carb. I am still thinking that having the needle valve in the position you now have it is going to cause fuel flow problems as the feed from the needle valve is up hill to the carb. Let me know how it works out, Thanks Dave

Fubar-One

My Feedback: (1)

I wonder if the FP carbs will fit on the LA engines. They are supposed to be pretty close to the same engines, aint they? I know you can buy some of the FP carbs still from Tower Hobbies.
[link=http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXCA58&P=ML]OS Carburetor #3A[/link]

phread59

Here is what I would do. Put the needle valve back to horizontal. If the arm clears that part is done. If not move in 1 hole snip the end off. Move the arm back closer to the firewall and refile your flat for the locking screw. Everyone is right, with a nose gear a little goes along way.

Now to access the needle valve. Use a dremmel cut off disc. Cut a slot in the end of the needle for a screw driver. cut an "X" in the covering where the needle valve is on the cheek. Peel it back and drill a hole. Let the covering flop back into place over the hole. Do not glue it down. Just seal the wood. Thin CA would work. The flaps hide the hole. And Allow acccess to the needle valve. Good luck.

Mark Shuman

newbieT

Mark,

Excellent idea, and well described. The only problem I see with that is having a screw driver flopping around a moving propeller trying to adjust the needle doesn't sit with me. But like I said, that's a great idea. I don't think the needle would quite clear the fuse side, so it would be necessary to have either a really large notch or what you suggested.

Dave,

I think you're right about the fuel flow problems. I was wondering, primarily, if having that configuration would cause a problem. I got two 'no' answers in the glow engines forum, but I'm not convinced it wouldn't...

Dan,

Yes, it's a 40LA (kicking myself for not getting an FX or 46LA...something I could reuse). I was also thinking I might be able to get an older carb with the needle still built in, but having the remote needle makes those adjustments so much safer. Back when I had my last plane they didn't have remote needles, they were just coming out as a mod. attachment to the engine. I bought a second needle valve before they came out, left the one on the carb wide open and mounted a second one further back on the plane, esentially building my own remote needle. I had my knuckles whacked a few too many times, and I always dreaded putting my fingers there...

Anyway, I think Dan's suggestion (was also a suggestion in the glow engines forum) to remove the bracket (or still use it) and mount just the needle housing on the cheek of the nose on the left side, just a bit further forward, is the way to go. Dave, you also mentioned moving the engine forward. In the PT40 the engine is mounted 1/4" forward backplate from the nose, I don't think it should be moved much further. Not to mention I already drilled the holes []

Thanks for all the suggestions guys. I'll post how I fare with this.

-Dave

Fubar-One

My Feedback: (1)

Let us know how it works out![8D]

newbieT

Alright, I got to working on it last night. Wife and I are moving so between packing and work, there's not much play I had a good look and decided where to mount the needle for best access for tuning and out of the way for the control horn. I'll get pics tonight, but let me tell you, the fuse cheek mounting idea was good...to a point. There just isn't enough room behind the engine! Anyway, I got the needle mounted and went on to mount the engine. The needle is slightly in the way for the rear-left mount screw (not a huge deal), but once I got that done I couldn't get the muffler screw in the engine housing! UGh...good thing you only really have to do this once. It'll work, it'll just take work Like I said, I'll post pics tonight...I also thought of mounting the needle on the bracket to raise it up a bit, it'd also give some more room to work with...we'll see...

brsseb

Hehe, just PM-ed you for help about this Dave for my PT-40. But looks like you are in the same situation .

I was installing my OS 46AX today, and the same problem occured. The AX seems abit bigger, and of course I had to mount it (holes are drilled) further back than you did [:@]. Compared to mine, your steering horn got a ballpark to move on . Thinking of putting the engine 1/3" or so further forward, but then Im breaking with the manuals restriction of 115mm between firewall and spinner backplate...And the AX seems damn heavy too. Think it will affect the balance too much? Was getting scared, since the steering shares servo with the rudder, that it would eventually limit my rudder movement as well, but I`ll do some experiments with this once i get the servos and horns in.

Note that I havent covered the model yet (its "happy sanding time" ....booooorrrrrinnngggg[:'(]), so I might be able do put the steering horn beneath the engine mount (looks like the rod will have to pass though a nasty bend, with the tube suddenly taking a hard turn though the tankfloor and lower firewall...can get scary. Perhaps its possible with a flexible pushrods?). Hate to part with the (so-far) excellent GP manual though.

Looking forward for those pictures, Dave .

newbieT

Oh man, been soooooooooo busy...but yea, I ran into the same problem and read your PM first thinking I'd reply with a link to this thread. I totally forgot that I hadn't posted any pictures! The wife and I just finished unpacking yesterday and still have more stuff to put away in the computer room. I'm just waiting to buy the radio to put in the servos and get going! But after all the expenses we're waiting a bit. Anyway, I mounted my needle on the side 'cheek' of the nose facing upward. That worked out just great. The nose and rudder have plenty of room, and the gas lines won't be caught up in anything. Now that I have a bit more time I'm going to be interested in making a work bench for building since the winter is fast approaching :-( But I hope to have this all done and in the air by the time I start college again (after 5 years) this fall! We'll see....good luck, brsseb.

-Dave

Amistad

Like you guys, I ran into the dreaded needle valve/nose steering arm problem while building my PT-40 with OS .46FX. During the steps of trial fitting control and drilling motor mount holes, I just moved the control rod and steering to below the engine. I routed the control rod under the fuel compartment. Expecting problems using the furnished control tube and rods, I've ordered the flexible golden rod controls.