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Cox Engine of The Month
3D printed beam mount .049 backplate
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3D printed beam mount .049 backplate
Any interest in a 3D printed beam mount .049 backplate?
It should have the same crank shaft center and the drive washer placement as a TD .049. The cylinder will be offset though. Can use a 128 or 80 TPI NVA assembly from a horseshoe/postage stamp backplate.
Can start with a reedy then transition over to a TD without any modifications.
It should have the same crank shaft center and the drive washer placement as a TD .049. The cylinder will be offset though. Can use a 128 or 80 TPI NVA assembly from a horseshoe/postage stamp backplate.
Can start with a reedy then transition over to a TD without any modifications.
Jason_WI- Top Poster
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Posts : 3123
Join date : 2011-10-09
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Re: 3D printed beam mount .049 backplate
I can see it having an interest for profile CL, not so sure about R/C. I'd buy one. Not sure that I'd buy more than one, as I have plenty of TDs/Medallions. Of course, I haven't seen the finished product either. With a TD piston and cylinder, I wonder how it would compare against a TD or a Medallion.
The Specualtive Mark
The Specualtive Mark
batjac- Diamond Member
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Location : Broken Arrow, OK, USA
Re: 3D printed beam mount .049 backplate
Definitely interested.
Bob
dckrsn- Diamond Member
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Age : 71
Location : Long Island, New York
Re: 3D printed beam mount .049 backplate
Yes, it is easier to mount reed engines on profile fuselages.
Levent Suberk- Diamond Member
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Join date : 2017-12-24
Location : Türkiye
Re: 3D printed beam mount .049 backplate
Mmmmm. Interesting concept. I'd be in for at least one, if not a few.
Thanks for developing this!
Thanks for developing this!
944_Jim- Diamond Member
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Posts : 2018
Join date : 2017-02-08
Age : 59
Location : NE MS
Re: 3D printed beam mount .049 backplate
OH sure! I'd be in for a couple. I've a couple more NV laying around!
Really looking forward for the Turbo Head's....Greg...Hint, hint, nudge, nudge...
Really looking forward for the Turbo Head's....Greg...Hint, hint, nudge, nudge...
Marleysky- Top Poster
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Re: 3D printed beam mount .049 backplate
Jason, I'd be in for at least 2.
Once again, the 128tpi will be the way to go.
Glad I started hoarding postage stamp plates
years ago.
Tnx,
Bob
Once again, the 128tpi will be the way to go.
Glad I started hoarding postage stamp plates
years ago.
Tnx,
Bob
dckrsn- Diamond Member
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Age : 71
Location : Long Island, New York
Jason_WI- Top Poster
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Posts : 3123
Join date : 2011-10-09
Age : 49
Location : Neenah, WI
Re: 3D printed beam mount .049 backplate
Jason this is a great fix for profile planes in general eliminating
the flat plate firewall. I would consider moving the beam back
so you have maximum possible strength. Would be a bummer
to end the day from a prop strike which happens all the time
with CL planes. See pic for reference, think a ground smack
could sacrifice a prop blade rather than one of the beams or both.
the flat plate firewall. I would consider moving the beam back
so you have maximum possible strength. Would be a bummer
to end the day from a prop strike which happens all the time
with CL planes. See pic for reference, think a ground smack
could sacrifice a prop blade rather than one of the beams or both.
1/2A Nut- Top Poster
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Location : Brad in Texas
Re: 3D printed beam mount .049 backplate
I was trying to keep the same drive plate position and crankshaft centerline as a TD .049. I can see where the unsupported ears can get broken easily.
I can certainly move the ears back and add support for the NVA like this.
If durability is more important than compatibility I can certainly have that option too.
I can certainly move the ears back and add support for the NVA like this.
If durability is more important than compatibility I can certainly have that option too.
Jason_WI- Top Poster
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Posts : 3123
Join date : 2011-10-09
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Re: 3D printed beam mount .049 backplate
I like the updated drawing you can access the NV nipple for ease of refueling
without flooding the engine. But but but the shortest distance from venturi
to reed valve will yield the most influx / power. The long stem requirement
for integrated fuel tanks robs power. Think Sportsman series how the design
improved influx.
Yes knowing how brutal CL flying is on props for the 1/2A size planes
the break rate in levels leading to engine damage:
1st - prop
2nd level - bent 5-40 prop screw
3rd level or degree - beams
4th worse case - crank or pin or ball socket
Note you have a chance to make a RC version for the Cox RC carb or for any aftermarket RC carb
that uses the TD carb body threads. Such as the Tarno RC carb.
without flooding the engine. But but but the shortest distance from venturi
to reed valve will yield the most influx / power. The long stem requirement
for integrated fuel tanks robs power. Think Sportsman series how the design
improved influx.
Yes knowing how brutal CL flying is on props for the 1/2A size planes
the break rate in levels leading to engine damage:
1st - prop
2nd level - bent 5-40 prop screw
3rd level or degree - beams
4th worse case - crank or pin or ball socket
Note you have a chance to make a RC version for the Cox RC carb or for any aftermarket RC carb
that uses the TD carb body threads. Such as the Tarno RC carb.
1/2A Nut- Top Poster
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Jason_WI- Top Poster
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Posts : 3123
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1/2A Nut- Top Poster
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Location : Brad in Texas
Jason_WI- Top Poster
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Re: 3D printed beam mount .049 backplate
17, 684 - peak 17,845 good runner nice and steady.
They are always a bit fussy when gold and normally
have a bit of gravity flooding in the case till the engine
is running. I use a Hornet 1/2A starter run it up without
the glow plug hot to lean out the mix in the case tends
to start up the cold ones in short order after that.
They are always a bit fussy when gold and normally
have a bit of gravity flooding in the case till the engine
is running. I use a Hornet 1/2A starter run it up without
the glow plug hot to lean out the mix in the case tends
to start up the cold ones in short order after that.
1/2A Nut- Top Poster
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Location : Brad in Texas
Re: 3D printed beam mount .049 backplate
Interesting idea there. Is it the same bolt pattern as the TD? Some guys would probably like it if there was a built in drum valve throttle/choke like the Cox one, except not sticking out so far. Maybe a horizontal hole across the back where you removed material. Even an air bleed hole provision. Just thinking out loud. Just roughing out a rotor hole that could be reamed out later for a stock brass size like 1/4". The first design looks great with the forward beams but there would not be much room for a throttle behind. I think that would be a seller, not thousands?
aspeed- Platinum Member
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Join date : 2013-01-18
Location : Leamington Ont. Can.
Re: 3D printed beam mount .049 backplate
Basically a choke tube type throttle. I thought those didn’t work to well with SPI cylinders. Tarno carbs recommended the use of a muffler for best results.
I can certainly update the back of this current design to integrate a choke tube. Probably work best with non SPI cylinders like the #3 I think.
Here are pictures showing the support material and the cleanup of the current part.
I can certainly update the back of this current design to integrate a choke tube. Probably work best with non SPI cylinders like the #3 I think.
Here are pictures showing the support material and the cleanup of the current part.
Jason_WI- Top Poster
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Re: 3D printed beam mount .049 backplate
Wow. That thing looks very strong! Another great job there! I really like the pictures of the backplate as it is being printed, or is that what it is? Regardless, the pictures are great. Thanks for sharing.
NEW222- Top Poster
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Location : oakbank, mb
Re: 3D printed beam mount .049 backplate
Here is a version for a Tarno carb. Would need to drill part way in to 7/32" then tap with 1/4-32 bottom tap. Has to be flush as the carb is threaded on. Would not fit on a standard TD firewall mount as the carb would stick out the back too far.
I'm not going to move any further on a choke tube version. Too many critical fitting parts that would be ripe for air leaks using 3D printed parts. Bernie sells this choke tube throttle that could be removed form the sure start tube and fitted to the back of the tarno mount. Would need to drill the hole for the spraybar then too.
https://coxengines.ca/throttle-conversion-for-cox-049-engine.html
I'm not going to move any further on a choke tube version. Too many critical fitting parts that would be ripe for air leaks using 3D printed parts. Bernie sells this choke tube throttle that could be removed form the sure start tube and fitted to the back of the tarno mount. Would need to drill the hole for the spraybar then too.
https://coxengines.ca/throttle-conversion-for-cox-049-engine.html
Jason_WI- Top Poster
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Join date : 2011-10-09
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Re: 3D printed beam mount .049 backplate
I was thinking just the shaft that the horn bolts to and the c clip, not the whole housing that goes with it. It would take drilling a few holes for sure.
aspeed- Platinum Member
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Join date : 2013-01-18
Location : Leamington Ont. Can.
Re: 3D printed beam mount .049 backplate
I have removed and tested the Cox air choke on a project it does get the job done.
The benefit of the size of it makes it suitable for a compact presentation.
The Cox and Tornado RC Carbs extend the fuel metering further away from
the reed which begs the question which will produce more RPM out of the
three types.
Interesting tidbit of engine tinkering nirvana to test a threaded version and
smooth bore version could be done. I have used Loctite 638 with a TD .020
and a smooth bored aluminum carb body for a G-Mark .03 carb worked like
a champ to hold and seal with no degradation over time using high nitro.
Seen used here a past engine of the month winner 10/2014
The benefit of the size of it makes it suitable for a compact presentation.
The Cox and Tornado RC Carbs extend the fuel metering further away from
the reed which begs the question which will produce more RPM out of the
three types.
Interesting tidbit of engine tinkering nirvana to test a threaded version and
smooth bore version could be done. I have used Loctite 638 with a TD .020
and a smooth bored aluminum carb body for a G-Mark .03 carb worked like
a champ to hold and seal with no degradation over time using high nitro.
Seen used here a past engine of the month winner 10/2014
1/2A Nut- Top Poster
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Location : Brad in Texas
Re: 3D printed beam mount .049 backplate
That looks good Jason to incorporate a carb without a lot of hassle would be great , Are you going to put one together and run it ?
getback- Top Poster
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Re: 3D printed beam mount .049 backplate
I need to find my 1/4-32 tap or order a new one.
Used to be able to buy the AP .061 carburetors pretty cheap and run a 1/4-32 die on the mounting base to put threads on for use on a TD. The source for those has dried up. Not sure what the stock status of the TD RC 05 carburetor is at Cox International. If it's even worth the effort to change the design to mount the carburetor at a 45 degree angle kinda like a queen bee. Hopefully not turn it into a paper weight like the queen bee that is being anemic on power. This would shorten the design up a bit by doing this and would still allow the use of a TD venturi and spraybar for CL use. There are lots of horseshoe and stamp backplates out there to rob the NVA assembly from for little cost VS a Tarno carb, TD RC 05 carb, or TD venturi assembly.
My main focus for the beam mount was for the profile CL plane use. If R/C was needed then use a throttle ring on the cylinder.
I have 4 of the standard NVA beam mounts available for testing. If you are willing to run one and report back the results with any issues good or bad I will send you one. First come first serve via a private message. You will need to install your own NVA assembly (80 or 128 TPI), reed, circlip, and gasket.
Used to be able to buy the AP .061 carburetors pretty cheap and run a 1/4-32 die on the mounting base to put threads on for use on a TD. The source for those has dried up. Not sure what the stock status of the TD RC 05 carburetor is at Cox International. If it's even worth the effort to change the design to mount the carburetor at a 45 degree angle kinda like a queen bee. Hopefully not turn it into a paper weight like the queen bee that is being anemic on power. This would shorten the design up a bit by doing this and would still allow the use of a TD venturi and spraybar for CL use. There are lots of horseshoe and stamp backplates out there to rob the NVA assembly from for little cost VS a Tarno carb, TD RC 05 carb, or TD venturi assembly.
My main focus for the beam mount was for the profile CL plane use. If R/C was needed then use a throttle ring on the cylinder.
I have 4 of the standard NVA beam mounts available for testing. If you are willing to run one and report back the results with any issues good or bad I will send you one. First come first serve via a private message. You will need to install your own NVA assembly (80 or 128 TPI), reed, circlip, and gasket.
Jason_WI- Top Poster
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Posts : 3123
Join date : 2011-10-09
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Re: 3D printed beam mount .049 backplate
I will test one and report via a vid and performance results.
PM sent, look forward to it thank you Jason.
PM sent, look forward to it thank you Jason.
1/2A Nut- Top Poster
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Location : Brad in Texas
Re: 3D printed beam mount .049 backplate
I have the Queen Beast that now makes more power then a TD .049 - .051
Truly between the .049's and the .09
Cox Queen Beast .074 / Kamtechnik Turbo Plug Adapter Test
With Muffler and pressure tap APC 6x3
Static Peak 19,783 rpm / .214 hp - 158w / 56.2 mph pitch speed
Impressive 23.3 oz thrust!
OS P4 turbo plug / 25% nitro / 20% oil
Truly between the .049's and the .09
Cox Queen Beast .074 / Kamtechnik Turbo Plug Adapter Test
With Muffler and pressure tap APC 6x3
Static Peak 19,783 rpm / .214 hp - 158w / 56.2 mph pitch speed
Impressive 23.3 oz thrust!
OS P4 turbo plug / 25% nitro / 20% oil
1/2A Nut- Top Poster
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Age : 61
Location : Brad in Texas
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