FunKey AS350 based on TREX 600CF

[getsuyoubi]

I managed to install the mechanics today, using some aluminum structural angle. The rear of the mechanics sits 15mm above the stock floor, the front 9.5mm. The aluminum angles do not extend all the way to the back of the mechanics because of the 3mm step in the floor caused by the additional plywood for the rear strut brackets. I'll glue a 12mm plywood piece in place that the rear of the mechanics rests on, so the mechanics pretty much rest on or at least very close to the strut mounts.
The main shaft ended up somewhat further back than the doghouse opening, but this seems to be closer to scale. I still have to enlarge that opening; right now the swash is just sitting on the doghouse, and the main shaft is not fully inserted.

[getsuyoubi]

I just tested whether a hose clamp is sufficient to hold the tail unit in place, and I failed. The clamp has just no effect whatsoever, not matter how much I tighten it. Granted, since I didn't remove the clamp lug, I wasn't able to move that clamp to the very end of the tail unit where the clamping action would be the largest, but at this point I don't want to risk it and cut off that lug. I may get a cheap plastic tail unit if I can still find one (I think they're only ten bucks now) and see what I can do with that. They do have the lugs on top and bottom, but they can probably be removed, and the two halves can be held together with a hose clamp.

Of course, now that I purposely look for it, I can't find those plastic units anywhere anymore...

[Keyrigger]

Suggestion: remove the lug and slot the other side to match. It should tighten with the clamp and throw in the screw as I suggested to keep it fixed in one spot. Take care.

Don

PS: Just do it, lol.

[Keyrigger]

One last point, make sure you can get a cable tie (40lb. capacity) around the boom either in front or behind the clamp to hold it to the lug as per the instructions. Don't use the hose clamp to hold the boom to the upper lug of the model as it will put a lot of stress on the fibreglass. You're getting there.

Don

[getsuyoubi]

Originally Posted by Keyrigger

Suggestion: remove the lug and slot the other side to match. It should tighten with the clamp and throw in the screw as I suggested to keep it fixed in one spot. Take care.

Don

PS: Just do it, lol.

I don't know, man - I don't want to burn any bridges! For a second or two I thought I can just slot the other side and try the hose clamp again in that same less-than-perfect position, but if that fails the original lug won't work anymore either, I think. I have to admit that I don't have any comparison, but my tail unit feels really massive. That could be the reason why it seemingly takes tremendous force to get it to clamp.

It turns out that not only the plastic tail units are hard to find, but metal units as well, so I may well be forced to convert to torque tube if I mess up my unit.

On a positive note, it seems that the main shaft that comes with the Align 3-blade head has the same 175mm distance between the upper Jesus bolt (it has two) and the main gear bolt as the 201mm long 600ESP shaft, which may mean that I don't have to get a second hole drilled in my ESP shaft to use that head at the right height. Instead I can just use the shaft that comes with that head. The lip that sits above the upper main bearing sits about 10mm higher than the lock collar on my shaft, though. If that's true then I may be able to slip my lock collar underneath that lip.
These measurements are based on pictures of that shaft that I found online, together with its overall length being quoted as 183mm.

[getsuyoubi]

Originally Posted by Keyrigger

One last point, make sure you can get a cable tie (40lb. capacity) around the boom either in front or behind the clamp to hold it to the lug as per the instructions. Don't use the hose clamp to hold the boom to the upper lug of the model as it will put a lot of stress on the fibreglass. You're getting there.

Don

I understand; I would never do that. Thanks!

[getsuyoubi]

I just ordered a plastic tail unit that I'll try to modify by cutting off the lugs on top and using a hose clamp instead. That should be straightforward since it consists of two halves that snap together, so I don't need tremendous force for clamping it tightly around the boom.

Once I get that one to work I will probably cut off the lug of my metal unit and try it once more, because then I'll have a backup solution.

[getsuyoubi]

While I'm waiting for my Align 3-blade head to arrive I'm having a good look at the elevator servo. I had to mount it in-between the frames since it wouldn't fit into the doghouse. Using the Align elevator servo mount (part number H60183) the servo arm ends up far off center, because that servo mount moves the servo inwards by 2cm. With the orientation of the servo the ball cannot be mounted underneath the servo arm because the linkage may bind against the servo. Altogether this results in the linkage rod being far from vertical, and the angle is so large that I'm getting concerned about it popping off. This angle will get even larger when I replace my current 58mm long linkages with shorter ones in order to get the swash inside the doghouse.
I will try to post pictures later.

I see two possible solutions:

1. Cut down that elevator servo mount by 1cm. This would require using machine screws and nuts to go from the servo lugs through the mount and the frame, instead of the stock self-tapping screws that would be way too long once I cut down the mount;

2. Put a bend in the elevator linkage rod to reduce that angle at the servo arm. This would be easy to do, but I'm worried that it may compromise the structural integrity of that rod.

Any thoughts?

[Keyrigger]

That mount is one that is normally used for the elevator servo on a couple of models. You might take a look for the boom servo mounting kit for the 600E or see if you can locate the servo mount for the 550. It will allow you to mount it to one side allowing a longer arm (though not really needed) and have your option of where to mount it. I know I could easily mount the 550 servo mount in the 600 frame. Its part number is 55023. Hope this answers your questions.

Don

[getsuyoubi]

I don't see how that would help in my case, because it seems like this would mount the servo upright (servo arm on top). I probably should have said that I got rid of the bellcranks a while ago since they seemed to have quite some slop.
My elevator servo is laying on its side, with the 20mm servo arm mounted horizontal along the servo, such that it points to the other end of the servo. So the ball end of that arm is still "above" the servo case, instead of extending over the edge of the servo and thus clearing it. That would actually be nice, because it would allow me to mount the ball underneath, which would get me closer to vertical.
I think I have to post some pictures to show this...:-)

[getsuyoubi]

OK, here are the pictures:

[Keyrigger]

Ok, wow, did I ever miss the boat on this, lol. The penny has dropped. So you are on the right path but you need to remove even more of the servo mount in order to minimize the angle of the rod. Have a look at the clearance you have available by putting the servo in place, then measuring the amount of the servo tray that you need to have in order to clear the fuselage. The anti-rotation guide will keep the motion linear but you might need to alter the endpoints of the servo. You can find out how much by using a swash plate levelling jig and seeing if you have the amount of travel of the elevator reduced as you get near the top and bottom of travel. Hope this helps.

Don

[getsuyoubi]

I just took a couple of measurements. To get the servo ball dead center, I need to move the servo outwards by about 14-15mm. If I remove the former in that area I have about the same amount of clearance between the servo case and the actual fuselage. This means instead of the 20mm this elevator servo mount gives me, I only need about 5 or 6mm.

My idea is to cut down that servo mount to 6mm or whatever is needed to still stay a millimeter or two away from the fuselage, drill out the holes for the self-tapping screws to 2 or 2.5mm, and use M2 or M2.5 screws and nuts to go through the entire assembly - servo lug, modified servo mount, and frame.

Does this make sense to you, or do you have a better suggestion?

[Keyrigger]

Sounds about right to me. I had to do the same with the 550 mechanics when I built my Jet Ranger. Standard mounting had it hit the body flange so I moved the servo in about 9mm and that allowed me to avoid a bugger of a job inserting the chassis. I think Nelson removed the flange to get the same result. If I am not mistaken, had I not done that, I would not have been able to install the shadow boxes that made up the engine compartment on the right side of the body. Now that I caught on (eye surgery on Monday, so that's my excuse, lol), I should be a bit better with suggestions from here on. I do miss my AS350 at times like these.

Don

[getsuyoubi]

Do you remember what you used to move the servo by 9mm? I seems kind of silly to me to cut down that 20mm servo mount to a mere 6mm, though I have to admit that I don't see anything else that I could obviously use.
Are you referring to your Jet Ranger that got destroyed when a plane crashed into it? I have to search for your build log, hopefully you mentioned how you moved the servo.

[Keyrigger]

Century supplied the spacers that were just plain plywood with holes to match the servo screw distance. They were 3mm ply and can be easily made. Another replacement would be the servo hold down tabs that normally come with Align mechanics as well as a multitude of others. Keep it simple but if the servo frame does the job, it's just a easy to use it along with the right length hardware. You're into that no matter what way you space it.

Don

PS: Yes, that's the one. I am playing around with the bones from that tonight doing some initial groundwork on the 700 size body.

[getsuyoubi]

I also thought about plywood, but you're right - why not cut down and use the servo mount I already have.

Besides this servo issue I'm currently waiting for parts, the plastic tail unit and the 3-blade head. Once I get that head I can determine what length linkage rods I need, and order them.
I already have the motor, an Align 730MX 850kV, to be run on 6s batteries. I cut the frames to make space for it, but I still have to modify the motor mount to accommodate the M4 30mm mounting pattern. Unfortunately the KDE adjustable mount has been discontinued.

[Keyrigger]

I thought that it was still available but when I looked at the part for more information on the KDE website, it showed disco'd. Sad.

Don

[getsuyoubi]

Strangely enough you can still put it in your cart, go to checkout and pay for it, only to receive an email later telling you that it's no longer available. Guess how I know...

[Keyrigger]

Slotting the motor mount shouldn't be too much of a pain.

Don