News:



  • June 18, 2025, 05:19:38 AM

Login with username, password and session length

« previous next »
Pages: [1]   Go Down

Author Topic: Odd Tank or Mod on Cox .020?  (Read 2002 times)

Offline Dave Hull

  • 25 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 2108
Odd Tank or Mod on Cox .020?
« on: August 30, 2018, 02:59:17 AM »
I was cleaning an newly acquired Cox .020 Pee Wee tonight and noticed an odd thing: the tank has a small hole on the face that bolts to the crankcase close to midway between two bolt holes. It is at a larger radius than the crankcase, so would be open (not blocked by case or case gasket) when assembled. I have not seen this on any other Pee Wees, or on any other Cox engines, period. As assembled, it was oriented at the top, so no doubt the engine would run just fine and only lose the tiniest bit of capacity. It is somewhere around .030" diameter. Located between the cylinder and the tank, it would be hard to notice it. With the starter spring nearly filling that gap, it would be almost impossible unless you take it apart. Nothing else looks any different. For example, the backplate has the standard top two filler/vent nipples. It does not appear to be anodized red like the rest of the tank, which makes it probable it is a "customer added feature."

Is this an odd factory configuration? If so, what was this extra tank vent for?

If it is a homebrew mod, what was it for? Some kind of free-flight cleverness?

Anyone have any ideas?

Dave

Logged

Offline Bill Hummel

  • 25 supporter
  • Trade Count: (0)
  • Captain
  • *
  • Posts: 410
Re: Odd Tank or Mod on Cox .020?
« Reply #1 on: August 30, 2018, 02:08:39 PM »
Hi Dave, trying to remember a small Cox helicopter, with a PeeWee 020, that had a hole that you describe. The engine rested on the mount facing “up”.  There was actually very little “dribble” from the hole. Flew for only a few minutes, barely enough power to rise. Hope this fuzzy recollection helps!
Logged
ama 72090

Offline Dave Hull

  • 25 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 2108
Re: Odd Tank or Mod on Cox .020?
« Reply #2 on: August 30, 2018, 03:08:34 PM »
Bill,

Wow, I never would have guessed at such a thing--but it totally makes sense. Maybe they were making these as factory mods from their normal engines? That would explain the apparent lack of anodizing in the hole. Don't want a separate production run of tanks for just the chopper?

Looks like Cox sold the Sky-Copter (FF) starting in 1975 with a Pee Wee .020. That might make even more sense because the tank is old enough to have the embossed Thimble-Drone markings on it. Not sure with the .020, but on the .049 that stopped doing that as time went by--presumably to cut costs.

Anyone else confirm or have an alternate explanation?

Dave



Logged

Offline Steve Helmick

  • 24 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 10265
Re: Odd Tank or Mod on Cox .020?
« Reply #3 on: August 30, 2018, 10:39:17 PM »
That's probably a better reason than my guess, but I'll put it out there anyway. What if the cylinder was rotated 90 to one side? Would that possibly suggest another reason for drilling the hole?  My brother had his setup like that in a Berkley Aeronca C-3 FF Scale...it flew very realistically...VERY anemic climb from ROG.  D>K Steve
Logged
"The United States has become a place where professional athletes and entertainers are mistaken for people of importance." - Robert Heinlein

In 1944 18-20 year old's stormed beaches, and parachuted behind enemy lines to almost certain death.  In 2015 18-20 year old's need safe zones so people don't hurt their feelings.

Offline Dave Hull

  • 25 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 2108
Re: Odd Tank or Mod on Cox .020?
« Reply #4 on: August 31, 2018, 12:21:44 AM »
Steve,
I don't understand the concept, can you explain further? I assume you would leave the backplate with the needle at the top, along with the standard fill/vent nipples? Or would you rotate that as well? Seems odd to do that on a FF. Since it would siphon then. Having a vent hole at the top of the tank would likely only make that worse.

If it is some kind of a FF trick I'd like to know, because that is where this one is likely to end up....

Dave

Mostly unrelated anecdote:

In NCLRA Quickie Rat, you can modify your crossflow ported engine by removing any metal that you want--but you can't make custom new parts and you can't add parts/metal. It is a venturi restricted event. The venturi size has been reduced periodically to keep the top speeds under control. A guy told me he picked up some K&B .40s--the standard engine for this event--off of ebay. He said that there was a complicated set of holes drilled thru the lugs and up into the case that you could not see when the engine was mounted. (A hidden hole kind of like this Cox tank.) Obviously, someone was trying or perhaps succeeded in circumventing the venturi restriction. Never did find out where that engine came from....
Logged

Offline Dan Berry

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 1102
Re: Odd Tank or Mod on Cox .020?
« Reply #5 on: August 31, 2018, 08:39:40 AM »
If it was in a helicopter with the prop on top it would be sensible.
You would need to cap the regular fill/vent holes prior to flight.
There have been a few copter designs for  FF event that no longer exists.
Logged

Offline dennis lipsett

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 1718
Re: Odd Tank or Mod on Cox .020?
« Reply #6 on: August 31, 2018, 09:09:12 AM »
We used to modify cox engines to get more flight time and it was a simple thing to drill a hole in the tank and run a very small fuel tube up to the intake nipple. obviously the other end hooked up to the fuel outlet tube on the tank. I had one set up to run about 5 minutes. a perfect tank wasn't real good for anything till you cleaned it and re plumbed it with a larger diameter copper tubing for everything. All tanked  pee wee engines got the treatment sooner or later.
Originally we used baloney cuts on the intake and overflow tubes. As soon as we learned about  bending the tubing into the slipstream they got a lot better runs. From 65 years ago
Logged

Offline Steve Helmick

  • 24 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 10265
Re: Odd Tank or Mod on Cox .020?
« Reply #7 on: August 31, 2018, 11:27:32 AM »

"Steve,
I don't understand the concept, can you explain further? I assume you would leave the backplate with the needle at the top, along with the standard fill/vent nipples? Or would you rotate that as well? Seems odd to do that on a FF. Since it would siphon then. Having a vent hole at the top of the tank would likely only make that worse."


Think about the Aeronca C-2 and C-3....they had opposed twins for power (and not much of that). NV at the top, but cylinder at 90 deg. to one side. I'm not sure which direction it was rotated, but it doesn't matter. Just looked more scale with the cylinder to the side.

Ol' Dad said he once flew a 1:1 scale Aeronca C-2 on a windy day and tookoff and landed backwards. It may have been an exaggeration, but not too far off truth. He also flew a Globe Swift, about which he said it was the only plane he ever flew that took off at 125, cruised at 125, stalled at 125 and landed at 125. 

For a helichopper install, I'd have a fuel filler and overflow hose on each spigot and have the open ends up by the crankcase, and see no reason to drill that .030" hole in the "top" of the tank. I'd guess that Cox decided to just have the operator connect the two spigots together with a single hose, put the hole in for a vent, and make it simpler for customers and/or assembly crew?  D>K Steve


Logged
"The United States has become a place where professional athletes and entertainers are mistaken for people of importance." - Robert Heinlein

In 1944 18-20 year old's stormed beaches, and parachuted behind enemy lines to almost certain death.  In 2015 18-20 year old's need safe zones so people don't hurt their feelings.

Offline Norm Furutani

  • Trade Count: (0)
  • Commander
  • ****
  • Posts: 210
Re: Odd Tank or Mod on Cox .020?
« Reply #8 on: August 31, 2018, 12:21:17 PM »
Dan Berry's post rang a bell. The 020 is from a Cox Hughes 500 helicopter or one similar. On this page you can see the PeeWee with the odd tank hole and if you look carefully at the instruction sheet, you can see the U shaped fuel tube that blocks the regular fill and vent. See:http://tmono.blog.shinobi.jp/%E3%83%98%E3%83%AA%E3%82%B3%E3%83%97%E3%82%BF%E3%83%BC%EF%BC%88%E3%83%91%E3%83%BC%E3%83%84%E3%81%9D%E3%81%AE%E4%BB%96%EF%BC%89/cox.020%E3%82%A8%E3%83%B3%E3%82%B8%E3%83%B3%E4%BB%98%20g-mark%20%E3%83%92%E3%83%A5%E3%83%BC%E3%82%BA50

Norm
Logged

Offline Dave Hull

  • 25 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 2108
Re: Odd Tank or Mod on Cox .020?
« Reply #9 on: August 31, 2018, 12:30:08 PM »
Norm,

There it is! What I have is a helicopter engine. Who knew?

So now if I put this on a free-flight plane, I can expect it to go straight up, right?

Thanks, guys for solving this mystery!

Dave
Logged

Offline dennis lipsett

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 1718
Re: Odd Tank or Mod on Cox .020?
« Reply #10 on: August 31, 2018, 09:19:10 PM »
Steve,

You can leave the fill/overflow nipples open. They don't fulfill any function in the conversion. Remember that there is no fuel in the Cox tank. Needle valve placement is not critical either. Your aware of the relationship of the needle valve and the fuel nipple.
Keep the fuel line from the perfect or Atlas tank as short as possible and keep it level with the fuel nipple inside the tank. we did this when we were 8 so it is not rocket science.

dennis
Logged

Advertise Here
Pages: [1]   Go Up
« previous next »
Tags: