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Older OS .15 throttle arm

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Old 02-22-2014, 09:33 PM
  #1
hogflyer
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Default Older OS .15 throttle arm

I recently acquired a large amount of models and engines from an elderly gentleman who can no longer participate in the hobby. He basically gave me everything he had since he was at the point where he was going to have to pitch it (one of those deals where you hate to take all of his entire hobby away from him, but also knowing it's going in the trash if it's not taken). Along with some almost new Cox engines - Golden Bee .049, TD .049, Queen Bee .074, TD .09 was a NIB OS FS-20 and FT 1.20 Gemini along with several planes and old radios.

One of the planes is a Goldberg Eaglet 50 with an old OS Max III .15. I'm not sure what the plane was covered with, but it appears to be a plastic covering that was painted. It had old Ace Commander servos installed, and either a Hobby Shack Aero Sport radio or World Models Blue Max radio (both look brand new and unused - not a mark, scratch or dirt anywhere on them). I did find one issue with

The OS .15 seems to have very little run time on it, and the plane appears like it may not have been flown. But I have found one issue with the engine - the throttle arm was broken. Is this going to some weird part that is next to impossible to find, will something off newer OS .10/.15 work (I'd hate to buy a new carb just to get the throttle arm), or would somebody happen have one in a parts drawer?

Also, will this engine have enough power to fly the plane, or should I consider changing it out for a Veco .19 or OS .20?

Hogflyer

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Old 02-22-2014, 09:39 PM
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I think I had a problem like this along the way and used an old larger "STD" size servo arm for the broken arm.
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Old 02-23-2014, 04:05 AM
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Hi Hogflyer,

Ditto what skaliwag said about the servo arm replacement.

My OS MaxIII .15 still runs. Although rather 'anemic' now, because I 'pushed' it too hard/overheated it, in a pusher design...
(My only attempt at hand carving wood props, I was sanding the first, then realized... I forgot to make it a pusher prop ! Doah !)

I recall it was a great runner. No powerhouse, but easy to start. Tornado white nylon 8-4. (A MA 8-3 would work)

Ditch the exhaust deflector. Drill/file out the muffler exit. The 'phoney phillips' muffler strap screw will strip out. Drill/tap for a 4-40 allen cap screw.

The OS.20 / Veco.19 might be a better bet. Do not forget the Castor oil...

The CG Eagle (.40 size) was our 'staple' trainer. When the 'Wings' were won with them, we would 'soup them up'.
The wings were 'clipped' to the next rib in...control surface area doubled...and when the nosegear wore out, they were converted to taildraggers...

The smaller 'Eaglets' were mostly handlaunched, due to the small wheels on our less than perfect runways...

How much does your Eaglet weigh?
It looks beautifully built...

Good Luck, It was built to Fly !

Take care,
Have fun,
Dave'crosscheck'Fallowfield
Maac 6437
Unabashed Combat Team
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Old 02-23-2014, 05:31 AM
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Quote:
Originally Posted by skaliwag View Post
I think I had a problem like this along the way and used an old larger "STD" size servo arm for the broken arm.
I have done that also. It works very well.

Ken
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Old 02-23-2014, 06:05 AM
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Yep, servo arm, or 1/32" steel shim that is cut out, drilled to fit and bent. I used some black steel strapping material and have a small punch for the holes. A drill will work too.
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Old 02-28-2014, 06:47 AM
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Here's a comparison of the steel and plastic throttle arms on the MAX-III .15:

George
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Old 02-28-2014, 11:54 AM
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My FP .15 has a Futaba throttle arm, one other engine too I forget. Works perfectly. And every servo comes with a spare.
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Old 03-02-2014, 06:22 PM
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Default Throttle arm fixed!

I solved the throttle issue the easy way. I remembered I have complete but old, burnt-up, junk OS .10 FSR prime for the parts donation. After a bit of a search I did find it and pulled the throttle arm off. I used the original retaining screw and spacer from the OS .15 and the throttle arm from the .10 and it looks like it'll work just fine. The .10 throttle arm is spaced out a bit further, but I think that will be a benefit since it won't be as close to the case.

Dave - the plane, with the engine/muffler, but no radio or fuel tank weighs:
Fuselage/engine: 26 ounces (1lb 10 ounces)
Wing: 9.4 ounces
Total: 35.6 ounces (2.2 lbs)

With today's lighter weight radio's it's possible it'll come in just over 3lbs so a.15 may fly it. I put one of the .20's I have up to the nose to check the bolt spacing and it's going to be a real pain to try to switch engines. There's not a lot difference between the two, but just enough to elongate the hold down holes. I do have a NIB Magnum .15XLS for my Sig Lil' Extra that may be a better bet. I suspect that .15 XLS will have as much power as a 30+ year old OS .20 and it may end up being a bolt-in swap or require less modification to fit (not to mention having to deal with what ever paint was used on it).

Hogflyer

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Old 03-02-2014, 07:35 PM
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The 15 will fly the Eaglet 50 great! It will fly on the Cox .09 also. I am building another Eaglet 50 now .. Both use the K&B 20 and rarely use more than 1/2 throttle.
The G120 would be steet in my Cub.

Fly and ENJOY the Eaglet 50. Its a fun plane.
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Old 03-03-2014, 05:51 PM
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I flew my Eaglet 50 on an Enya 15 III for years. It flew perfectly with that combo. It was moderately fast but slowed down really well as well.
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Old 03-04-2014, 02:10 AM
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Quote:
Originally Posted by hogflyer View Post
I do have a NIB Magnum .15XLS for my Sig Lil' Extra that may be a better bet. I suspect that .15 XLS will have as much power as a 30+ year old OS .20 and it may end up being a bolt-in swap or require less modification to fit
Oooh, don't diss the old-school stuff...
The older engines will swing larger props without any complaint, while the newer more "powerful" engines will need a smaller prop.

As an example, a 30 year old, baffle piston, Veco .19BB will swing a 9x4 prop at around 12500rpm all day, while the .15XLS will not take anything larger than an 8x4 and deliver around 15000rpm. The XLS would in fact be even happier on a 7x4 prop. So depending on the plane, the old-school stuff still serves a purpose.

Looking at the pictures, I'd say keep it old-school...

Last edited by Mr Cox; 03-04-2014 at 02:13 AM.
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Old 03-04-2014, 07:11 AM
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Quote:
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..............the old-school stuff still serves a purpose.
Thank goodness ----- otherwise, I would be tossed on the trash heap.
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