Schluter Bell Huey Cobra: just bought one

[redbird300]

Thank you again.

And some more news. I started working on the engine (a VECO 61), and unscrewed the cylinder head, in order to clean it:





A lot later, and that is really a whole lot later ... almost cleaned, the cooling fins took a lot of time and fiddling, just needs some more polishing to remove all the remaining scratches, IMO:

[redbird300]

Originally Posted by Ah Clem

redbird300,

Makes me want to ship mine to you for restoration!

Great job sir!

Do it, do it ! (and I hope you have a good lawyer ... I might forget to ship it back, over and over again...)

[Ah Clem]

ROTFLMAO!

[redbird300]

And I opened the gearbox, to clean and inspect it. The gear ratio is marked on the box, clever. It says "Schluter 1:3:10,5" (second picture).

[Ah Clem]

You will be able to see the oil level in that one. An advantage over the metal one.

I think I used to use an allen wrench for the metal one in the Hirobo UH-1 as a dip stick.

What kind of oil are you going to use?

[sarpilot]

Wow look at that gear train!

Sent from my DROID3 using Tapatalk 2

[redbird300]

Originally Posted by Ah Clem

You will be able to see the oil level in that one. An advantage over the metal one.

I think I used to use an allen wrench for the metal one in the Hirobo UH-1 as a dip stick.

What kind of oil are you going to use?

Yes, but the metal ones like you have were better, they didn't leak, as I heard.
Don't know about the type of oil yet, I'll clean it for now, we'll see later. I'll leave it empty for the moment, I guess. BTW, any advice on which oil would be best ?

[Ah Clem]

I have one bottle of Hirobo Transmission oil left. There is no indication of what it actually is. I assume that it is something that was commonly available at the time. It seems somewhat heavy and has a motor oil/petroleum smell to it. I do not know if it would attack a plastic transmission case.

I thought I would get smart when I built the Hirobo UH-1 in 1980. I sealed the transmission with Permatex gasket sealant, as those transmissions had a reputation for leaking (they were metal and the instructions directed you to lap the mating faces of the transmission, as I recall). You were supposed to epoxy and bolt the transmission halves together.

The Permatex sealed fine in the beginning, but the more I flew it, the more the bearings started moving around in their journals due to the Permatex being soft.

I tore the whole machine down for movie work in 1990. That time, I glued the transmission case together with JB Weld (gluing the bearings in with it as well). I did not fly it that much, but it never leaked again.

I will probably follow the same path with the Schluter as I did with the Hirobo (epoxying the case together with JB Weld. It will make it painful to get it apart to change the bearings, but it will now, hopefully, never leak.

The biggest issue I have is the head. I can fly it with the Helibaby style head which, if memory serves, will be very slow on cyclic and have lots of lag in terms of vertical performance.

The other thing I can do, is mount a modern head on it and go FBL with collective. This would be safer for the machine, but not correct for the machine.

I will have to start tearing it down to see what I have and if the stock head is in good condition, before I consider modifying anything. The expert head, would be a step up, I think.

[Inverse]

[QUOTE=Ah Clem;4211560
The other thing I can do, is mount a modern head on it and go FBL with collective. This would be safer for the machine, but not correct for the machine.[/QUOTE]

I see nothing wrong with retro fitting as long as you keep the original parts and it's reversible.

[Ah Clem]

"I see nothing wrong with retro fitting as long as you keep the original parts and it's reversible."


Thank you-that makes very good sense!

[redbird300]

Thank you for all the tips about the oil and the gear box, Ah Clem. I was thinking JB Weld myself, and I'm glad you confirmed, as I didn't know if it was the right thing to do.

Back to business: all parts of the gearbox are cleaned and some even slightly polished:



Still need to clean the bearings though, and replace one or two of them, as they feel a little notchy. So I'll bolt it back together without glue or oil for now, until I found the right bearings, taking care not to loose any parts. I'll continue working on the motor in the mean time.

[sarpilot]

Looking at your great pics of transmission it aint made like that anymore..... 1980 ish it was a master machinist turned out by hand most likely no cnc and computers back then baybee you old guys know the deal...

[redbird300]

Originally Posted by sarpilot

Looking at your great pics of transmission it aint made like that anymore..... 1980 ish it was a master machinist turned out by hand most likely no cnc and computers back then baybee you old guys know the deal...

Funny, I was thinking about the same thing. This transmission is almost 40 years old (1974), and many new products don't come even close to the quality and finish of these gears. I guess it's the cost factor that plays a huge role nowadays.

[redbird300]

I unscrewed the inner part of the clutch from the motor tonight. There was not much cleaning to do, just a little bit of polishing to remove a few blue-reddish marks on the metal at the exact spots where it grips first in the outer ring, caused by friction heat without a doubt.

[redbird300]

Just found out that the oil to be used in the transmission gearbox should be "SAE90 transmission oil for hypoid gears". It's also mentioned in the manual, and several specialised websites confirmed this. This is specific oil for these kind of old gearboxes, easy to find if you google it.

[Ah Clem]

Thank you very, very much for that information, sir!

[redbird300]

Originally Posted by Ah Clem

Thank you very, very much for that information, sir!

You're very welcome.

BTW, you can download the complete original manual here, but I guess you already have one.
http://www.vrhc.co.uk/RC%20Helicopte...d%20manual.pdf

Anyhow, the oil info is on the first line of page 15, as the page numbers are printed in the manual.
In a PDF reader, that would be page 16 (front page is counted as page 1).

[redbird300]

BTW, the very first lines of that same manual are kinda funny, when you read them now (meaning in 2012):

[redbird300]

I disassembled the rest of the motor today. I don't know much about these motors, but luckily some friends and fellow club members do have a lot of experience. Using their advice, I manged to take the (dirty and very sticky) motor apart without a scratch.

No real problems, only the radial fan was a bit hard to remove, as it has been pressed all these years onto a brass cone on the shaft. I did not remove the nut completely, but let it sitting at the end of the shaft, and a short but firm knock with a hammer on that nut (not damaging the shaft that way) while supporting the cooling fan carefully, did the trick. The fan popped right of. A good vice and a rubber hammer did the rest, as no part came loose without using some careful force, it's like it's all glued together.

Just to keep things clear and avoiding to mix up any parts, I put each group of parts in a plastic bag. Will be handy when assembling the whole thing again. Time to start cleaning it all now, patiently and bag by bag. CU (much) later.

[bossee]

Hi,

Nice helicopter You have there. Do You plan to get it into the air?

One way of cleaning an engine from old oil and dirt burnt on the surface is to take the engine apart and boil parts in glycole (do it outdors, hazardous fumes) for some hours. I made a silencer as new again that way (see image) below).

If You need mechanical replacement parts for this old Schlüter Cobra helicopter there is a guy in Germany that sell replica of Schlüter DS22 that use same mechanics as the Cobra. For example the plastic gearhousing and it's mounting ears break easy on the original housing but this guy make new ones.
http://www.modellbau-graef.de/
Load the pages into Google translatator if You do not understand German.

Another good page for Schlüter/Hegi Cobra parts and info is this:
http://www.helioldie.de/cobra.htm

I have an old Schlüter Cobra myself, my Cobra heli was competing in first helicopter competition/meeting in my country October 28 1973, it placed 2nd. The helicopter is still in great condition but it will need new plastic gearhousing, new blades and probably change to a more modern engine (the original Veco 61 has seen better days). Image below of my Cobra (and me) some winters ago and an image from that first helicopter competition/meeting (red arrow pointing at my Cobra heli, I was not at that competition, the original builder was there andf flew it).

/Bo