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Cox Engine of The Month
Fun with Generic, Non-Threatening Title
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Fun with Generic, Non-Threatening Title
First off, my original title for this thread was going to be, “Fun with Pipe You-Know-Whats, or Experiments with Eye-E-Dees”. Eye-E-Dees standing for “Improvised Engine Docks”. But I figured that if I put all those key words in one title, some NSA web monitoring bot would flag it and I’d be on a terrorist watch list for the rest of my life.
This thread is for my scheme for developing a simple Testors pipe bomb engine mount for an airplane as I talked about in Bob's thread. I normally wait until I’ve completed my build or project before do a build thread so that I can either show a successful project, or just discard the evidence of failure and pretend it never happened. But I figured I’d post as I go on this one.
Thoughts on this project:
1. The consensus on these pipe bomb engines is that they either run great, or they’re a P.O.S.
2. They obviously lack any proper mounting tabs making them re-usable after the donor model is toast.
3. The attached fuel tank is oddly shaped and gets in the way of mounting the engine.
For the hit-or miss nature of these engines. I’m thinking it may be partly due to the way the fuel tank is attached to the body. It is a press fit, and the only thing that makes a seal is a shallow groove molded into the case, and a small ridge around the reed housing in the tank. This seems like a recipe for air leaks around the case back. Or not. I may just be full of it.
The mounting tab issue. If only Testors had just put the slotted tab on both sides of the engine instead of just the right side. It would make for an easy mount. The left side has no feature at all that can be used to hold the engine. The engine will have to be encapsulated somehow.
The tank issue. What the hell? I don’t know who designed such a strange shape. But just, damn…
The tank issue is the first thing I’ll tackle, as it is the biggest problem with making a compact mount. Looking at it, I wondered just exactly how the fuel is picked up in the tank. Since one of the tanks I have is cracked, I figured I’d just take a razor saw and hack off the back plate on the tank. It’d permanently ruin the tank, but what the hell. This is a “trash” engine anyway. So, cutting off the back and looking in shows…. Ah-HAH! A fuel nipple. I can work with this.
A little more work the razor saw, a sanding block, and an X-Acto knife gave me this.
So, slipped into the engine case it looks like this. I didn’t want to snap it back into case groove just yet, so it’s just loosely fit to get some measurements.
More to come,
The Non-Threatening Mark
This thread is for my scheme for developing a simple Testors pipe bomb engine mount for an airplane as I talked about in Bob's thread. I normally wait until I’ve completed my build or project before do a build thread so that I can either show a successful project, or just discard the evidence of failure and pretend it never happened. But I figured I’d post as I go on this one.
Thoughts on this project:
1. The consensus on these pipe bomb engines is that they either run great, or they’re a P.O.S.
2. They obviously lack any proper mounting tabs making them re-usable after the donor model is toast.
3. The attached fuel tank is oddly shaped and gets in the way of mounting the engine.
For the hit-or miss nature of these engines. I’m thinking it may be partly due to the way the fuel tank is attached to the body. It is a press fit, and the only thing that makes a seal is a shallow groove molded into the case, and a small ridge around the reed housing in the tank. This seems like a recipe for air leaks around the case back. Or not. I may just be full of it.
The mounting tab issue. If only Testors had just put the slotted tab on both sides of the engine instead of just the right side. It would make for an easy mount. The left side has no feature at all that can be used to hold the engine. The engine will have to be encapsulated somehow.
The tank issue. What the hell? I don’t know who designed such a strange shape. But just, damn…
The tank issue is the first thing I’ll tackle, as it is the biggest problem with making a compact mount. Looking at it, I wondered just exactly how the fuel is picked up in the tank. Since one of the tanks I have is cracked, I figured I’d just take a razor saw and hack off the back plate on the tank. It’d permanently ruin the tank, but what the hell. This is a “trash” engine anyway. So, cutting off the back and looking in shows…. Ah-HAH! A fuel nipple. I can work with this.
A little more work the razor saw, a sanding block, and an X-Acto knife gave me this.
So, slipped into the engine case it looks like this. I didn’t want to snap it back into case groove just yet, so it’s just loosely fit to get some measurements.
More to come,
The Non-Threatening Mark
batjac- Diamond Member
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Re: Fun with Generic, Non-Threatening Title
Looking like a loaded thread already!
Phil
Phil
pkrankow- Top Poster
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Re: Fun with Generic, Non-Threatening Title
What the heck is that crankcase made of anyway, it's not even metal, is it? What about the internal crank tube, it must be bushed, right?
Good luck, maybe you can re-engineer it into something useful. Maybe even get enough power to hurt itself. The first Testors Pipe Bomb to ever actually explode during flight. That would be fun.
Rusty
Good luck, maybe you can re-engineer it into something useful. Maybe even get enough power to hurt itself. The first Testors Pipe Bomb to ever actually explode during flight. That would be fun.
Rusty
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while you're doing it!
My Hot Rock & Blues Playlist
RknRusty- Rest In Peace
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Re: Fun with Generic, Non-Threatening Title
RknRusty wrote:The first Testors Pipe Bomb to ever actually explode during flight. That would be fun.
Rusty
Already done. My old Fly 'em P-40 would never run until I fitted a 6" prop in place of the dinky little 3 blader. The rod didn't like the extra load and exploded on launch. Well, not actually exploded, but it did go bang.
Mark. That's a really neat experiment. There were many of these engines which had a backplate to utilize a separate tank already.
Here's the metal case version.
This one has a different tank again with a long tube running along the mounting lug to a front rotary valve. These had a multi-position fuel clicker rather than a threaded needle valve. They were a dismal failure. I don't have the fuel control for this one.
Here's one out of a Testors Galax hovercraft. The rear mount is the same screw pattern as a Babe Bee. They have a snap-in venturi which this example is missing. I've since got a complete one which isn't pictured. I have removed a venturi from a Cox postage stamp backplate which I plan to epoxy in place. This will be easy to use on any plane designed for a radial mount .049.
Finally, this series 8000 was apparently the best example, with the inbuilt radial tank mount, although the mount pattern is different from the Galax or Cox/Cub pattern.
Hope the info helps.
Rod.
Oldenginerod- Top Poster
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Re: Fun with Generic, Non-Threatening Title
I am looking forward to the mounting system you come up with.
Phil
Phil
chevyiron420- Gold Member
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Re: Fun with Generic, Non-Threatening Title
chevyiron420 wrote:I am looking forward to the mounting system you come up with.
Phil
Me too. I have one like the one in rod's first pic, minus the needle valve assembly and the fuel nipple. But postage stamp parts seem to be a direct fit.
KariFS- Diamond Member
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Re: Fun with Generic, Non-Threatening Title
too good !! Mark I hope this works out for some reason // and Rod why do you have all those Bombs anyhow ? I do have a couple only cause I cant get rid of themMaybe even get enough power to hurt itself. The first Testors Pipe Bomb to ever actually explode wrote:
getback- Top Poster
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Re: Fun with Generic, Non-Threatening Title
getback wrote: too good !! Mark I hope this works out for some reason // and Rod why do you have all those Bombs anyhow ? I do have a couple only cause I cant get rid of them
Sell them on FleaBay, list them as a "COX type" engine....they do go cheap:
http://www.ebay.com/itm/Gas-Engine-For-Model-Airplane-With-Propeller-COX-Type-Working-/171732884181?nma=true&si=o4%252FSG0k8OEbTSIByWFhwjN2n29w%253D&orig_cvip=true&rt=nc&_trksid=p2047675.l2557
OMG. check the location of the seller.....how funny is that!!
Marleysky- Top Poster
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Re: Fun with Generic, Non-Threatening Title
$16.50 is WAY more than I'd spend on one of these, even if I do get this mounting thing down. I like getting them free like I did at the swap meet.
The Frugal Mark
The Frugal Mark
Last edited by batjac on Fri Apr 03, 2015 1:41 pm; edited 1 time in total
batjac- Diamond Member
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Re: Fun with Generic, Non-Threatening Title
Some years ago I needed glow heads for my wen macs and I called the testors parts dept. I got a very nice lady on the phone, and asked her about engines. Even though she didnt know what I was talking about she asked me to send her a picture of what I wanted, and I did. I didnt expect to hear back from her, but one day she called. She had found two big boxes full of two types of engines. They came up with a price of five bucks each, and I choose the hovercraft on pictured above. When I got a few extra bucks I would call her and order a few. I mostly used them for parts to keep my wen mac's running but did fly a couple. They ran ok but the carb/motor mount would come loose and soon the engine would be vibrating around. I still have a few of them but have used up most of the glow plugs.
Phil
Phil
chevyiron420- Gold Member
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Re: Fun with Generic, Non-Threatening Title
batjac wrote:$16.50 is WAY more than I'd spend on one of these, even if I do get this mounting thing down. I like getting them free like I did at the swap meet.
The Frugal Mark
Well that's because it was a "COX Type" engine. The Wen Mac Testors sell for less. But. I hardily agree, FREE is the best price for those versions.
Here's one I lost by 50 cents to a sniper....http://www.ebay.com/itm/221728412301?ssPageName=STRK:MEDWX:IT&_trksid=p3984.m1435.l2649
The "shot down by a sniper" Marleysly
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Re: Fun with Generic, Non-Threatening Title
Mark, 3/4" PVC looks promising. I had suspected this a few times.. but never took any measurements. Your (now round) back-plate should measure .790" and the nom. ID of the 3/4" PVC pipe (LOL..) is .800". Cutting a relief-slot for that single mount on the case; along with removing the cylinder and needle-valve, should allow the case to fit snugly (it will be tight) into the pipe. You may need to cut a relief slot (bottom?) to force the PVC pipe open enough for inserting the case. A 3/4" hole-sawn hole in the pipe would allow for remounting the cylinder.. which would lock the engine into the pipe. A firewall could be made with a 3/4" hardwood dowel, wrapped with enough masking tape to fit inside the pipe.. approx. 1/2" to receive sm. wood-screws. The question is.. how heavy would this be? Take some measurements and drill holes in the pipe for your needle and fuel-line. Be sure not to block the air-intake.
Re: Fun with Generic, Non-Threatening Title
Eric.getback wrote:Rod why do you have all those Bombs anyhow ?
I was given a Testors P-40 for Christmas when I was a kid. I treasured that plane because I know my parents couldn't really afford it- we were pretty poor. It gave me grief but I have a real soft spot for them. Truth is, the main reason I have so many is that I can't resist a bargain and it's the easiest way to accumulate spare glow heads for the earlier Testors/Wen Mac engines which I intend to use.
Rod.
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Re: Fun with Generic, Non-Threatening Title
Was there ever a piston/rod resetting tool available for the Testors .049? I never checked the fit of my Cox tool to see if it could be used.
Rod, you mentioned having an engine "grenade" using a 6"D prop. Do you remember what pitch the prop was.. and what type of fuel you were running? I wonder if it was just a bad rod.. or whether the ball-socket joint was loose causing the failure?
Rod, you mentioned having an engine "grenade" using a 6"D prop. Do you remember what pitch the prop was.. and what type of fuel you were running? I wonder if it was just a bad rod.. or whether the ball-socket joint was loose causing the failure?
Re: Fun with Generic, Non-Threatening Title
roddie wrote:Rod, you mentioned having an engine "grenade" using a 6"D prop. Do you remember what pitch the prop was.. and what type of fuel you were running? I wonder if it was just a bad rod.. or whether the ball-socket joint was loose causing the failure?
Failure of the rod happened at the crank pin end. I think the ball socket is a circlip type. It was a lot of years ago and I had no idea of prop pitch when I was a boy. I do remember it was yellow, so I suspect it was a Tornado. Fuel would have been Cox fuel, I think from a red & white can. Didn't know much about nitro then either, but after initially using up the supplied Testors fuel, I could never get the Testors to run again on my other standard fuel. It wasn't until my dad enquired at a large depatement stor (Myer in Melbourne) that we were told the .049 engines needed high nitro. Sold him a can of Cox fuel and problem solved. One reason I went for the larger prop was to make it easier to flick as the spring starter have broken by this stage.
Rod.
Oldenginerod- Top Poster
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Re: Fun with Generic, Non-Threatening Title
I understand Rod even though my dad flew CL as a kid they were all home made simple fly /dogfight/crash'em wood models . This would have been in the 40s , so the only plastic model I ever got was the PT-19 trainer after that it was build your own and the one kit was Stuntman 23 that I duplicated so I would have 2 with I still have I guess that's why now I may not have much $$$ but I do have STUFFOldenginerod wrote:Eric.getback wrote:Rod why do you have all those Bombs anyhow ?
I was given a Testors P-40 for Christmas when I was a kid. I treasured that plane because I know my parents couldn't really afford it- we were pretty poor. It gave me grief but I have a real soft spot for them. Truth is, the main reason I have so many is that I can't resist a bargain and it's the easiest way to accumulate spare glow heads for the earlier Testors/Wen Mac engines which I intend to use.
Rod.
getback- Top Poster
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Stuntman 23
Thinking back, I find it amusing that this aircraft had a wing made up of four die cut sections, probably so the kit box could be kept smaller!
I wish that mine had survived just so I could see how my building skills have improved.
Is this kit still available somewhere?
I wish that mine had survived just so I could see how my building skills have improved.
Is this kit still available somewhere?
706jim- Gold Member
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Re: Fun with Generic, Non-Threatening Title
That 8000 interestingly enough, when laid as a sidewinder utilizes the Cox .049 Babe Bee tank mount hole pattern. With the needle facing the flier, this puts the tank suction line to the right side of the engine toward the circle outer for successful CL flight. If one wanted to use it for free flight or radio control, they'd mount the engine inverted, which would put the tank suction line to the bottom.Oldenginerod wrote:Finally, this series 8000 was apparently the best example, with the inbuilt radial tank mount, although the mount pattern is different from the Galax or Cox/Cub pattern.
Hope the info helps. Rod.
The "pipe bomb" engine used a clamping system within the RTF cowling to retain the engine. Being able to clamp the engine in similar manner without extensive engine modification would be a key to success, IMHO. However, there are more than one ingenious way to contain these engines successfully, as the OP indicates.
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Re: Fun with Generic, Non-Threatening Title
George, you may be right. I got the impression that the mounting pattern was just a bit out to the Babe Bee pattern. Maybe I was thinking of the earlier tank mount for the Testors McCoy.GallopingGhostler wrote:
That 8000 interestingly enough, when laid as a sidewinder utilizes the Cox .049 Babe Bee tank mount hole pattern.
Oldenginerod- Top Poster
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Re: Fun with Generic, Non-Threatening Title
The .049 Red Head engine mount is a touch wider, Rod, you're right about that. The 8000 Series with tank and mount lugs was a decent engine and I wished I had bought a couple when they were still available and cheap in their hay day.
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Re: Fun with Generic, Non-Threatening Title
Well, before going any further on making the mount, it behooves me to actually see if the engine will run with the tank cut off. I whipped up a temporary mount from some scrap wood, and clamped it to my test stand with a yellow Cox safety tip 5x3. And before you ask, no, the cable ties are not holding the engine to keep it from flying off. The engine is bedded in the wooden mount. The cable ties are to keep the engine from rotating clockwise due to the lack of a tab on the left side, although the torque should be enough to keep the amount of rotational movement down. This’ll be addressed in the real mount.
I was initially concerned because after I snapped the reed assembly back in the case, I realized that I had forgotten to clean up the reed valve and circlip before putting it back in the case. But it started up pretty okay when I figured out how many turns to open the needle valve initially. At 5 turns open it started. It was obviously not broken it, so I took it easy at first. I ran ¾ of an ounce slobbery rich. Then I ran another ¾ ounce at the 2-4 break with occasional trips up to max RPM, then back down. Then on the third ¾ ounce tank, I peaked it out at 3 ¾ turns open. It’s a little touchy yet. Still needs more break-in. But for most of the last tank it was holding steady at about 16,250 RPM. That’s good Bee performance, there. Hopefully the other engine I’m fixing up will do better as it’s from a car and doesn’t have the spring dragging on the shaft.
As usual, I neglected to charge the battery in my camera, so I only got a few seconds of video before the battery died. Again, this is me holding the camera in one hand while tweaking with the other. This was on the second tank as I was bringing it up to the 2-4 break. I’ll get better video when I get the engine mounted to a plane.
The Neglectful Mark
I was initially concerned because after I snapped the reed assembly back in the case, I realized that I had forgotten to clean up the reed valve and circlip before putting it back in the case. But it started up pretty okay when I figured out how many turns to open the needle valve initially. At 5 turns open it started. It was obviously not broken it, so I took it easy at first. I ran ¾ of an ounce slobbery rich. Then I ran another ¾ ounce at the 2-4 break with occasional trips up to max RPM, then back down. Then on the third ¾ ounce tank, I peaked it out at 3 ¾ turns open. It’s a little touchy yet. Still needs more break-in. But for most of the last tank it was holding steady at about 16,250 RPM. That’s good Bee performance, there. Hopefully the other engine I’m fixing up will do better as it’s from a car and doesn’t have the spring dragging on the shaft.
As usual, I neglected to charge the battery in my camera, so I only got a few seconds of video before the battery died. Again, this is me holding the camera in one hand while tweaking with the other. This was on the second tank as I was bringing it up to the 2-4 break. I’ll get better video when I get the engine mounted to a plane.
The Neglectful Mark
batjac- Diamond Member
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Re: Fun with Generic, Non-Threatening Title
While slightly off topic, while I was checking mark's clip on youtube I came across this one. https://www.youtube.com/watch?v=UY7qX75zlSM
While it's nothing particularly special in itself, I was surprised to see that the Testors McCoy had what looks like a K&B Stallion head fitted. People have been speculating a long time about alternative heads for the Testors engines, but this sort of proves that there is indeed an alternative to the hard-to-find Testors heads or a head adaptor. Last I looked the Stallion heads were available from MECOA.
Rod.
While it's nothing particularly special in itself, I was surprised to see that the Testors McCoy had what looks like a K&B Stallion head fitted. People have been speculating a long time about alternative heads for the Testors engines, but this sort of proves that there is indeed an alternative to the hard-to-find Testors heads or a head adaptor. Last I looked the Stallion heads were available from MECOA.
Rod.
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Re: Fun with Generic, Non-Threatening Title
Rod, I saw that some time ago, and found a thread on another forum that stated that the heads from a stallion, holland hornet, testors, wen mac were interchangeable. I posted elsewhere to see if some people with extra parts could confirm this, but didnt get anywhere. I took a chance and ordered a galbreath head for a hornet in hopes it would fit on my wen macs. It didnt. The threads are about .005 oversize. I made a thread chaser and with much work I got it to fit, but it doesnt work well. I have not run into a stallion head to try yet. I bet someone here has one they could try.
Phil
Phil
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Re: Fun with Generic, Non-Threatening Title
most of you will ask.. "why".. .. but this will definitely clamp the engine tightly when snapped-in. It still needs work.. (holes drilled for needle/fuel-line) I haven't modified my back-plate like Mark's yet. Lightening-holes could also be drilled. As I mentioned; this would mount on a hardwood dowel (peg) affixed to the firewall.
As far as "practicality?"... This might be best for a small speed model. "Pipe-Bomb Speed" with the only limitation being line-length.
The hole for the cylinder is "Roddie-overkill".. and more work than necessary. A wide-open slot for sliding the engine in "with cylinder attached".. would be the way to go. The curved bottom of the case fits nicely inside the radius of the pipe.
EDIT: I cut the bottom full-length with a razor-saw. The cut closes-up tight with no gap afterward. I filed a slot to insert a flat-blade screwdriver.
Twisting the screwdriver opens the gap, allowing for engine insertion.. and retention when released.
As far as "practicality?"... This might be best for a small speed model. "Pipe-Bomb Speed" with the only limitation being line-length.
The hole for the cylinder is "Roddie-overkill".. and more work than necessary. A wide-open slot for sliding the engine in "with cylinder attached".. would be the way to go. The curved bottom of the case fits nicely inside the radius of the pipe.
EDIT: I cut the bottom full-length with a razor-saw. The cut closes-up tight with no gap afterward. I filed a slot to insert a flat-blade screwdriver.
Twisting the screwdriver opens the gap, allowing for engine insertion.. and retention when released.
Last edited by roddie on Mon Apr 06, 2015 3:20 pm; edited 2 times in total
Re: Fun with Generic, Non-Threatening Title
A lot of ingenuity and quality handiwork, roddie, I'm looking forward to your finished product and flight report.
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