3D printed beam mount .049 backplate

 
Definitely interested.
Bob

Yes, it is easier to mount reed engines on profile fuselages.

Mmmmm. Interesting concept. I'd be in for at least one, if not a few.

Thanks for developing this!

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...

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

Here is one printed. Need to size the holes and polish the reed seal surface.

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.

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 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.

How's this? Added gussets and moved the NVA back.

Yes Jason looks good!

You can improve strength as shown / no reason to keep curved surfaces on the outside.

It runs!

With the .2” intake it was hard to get started but once it ran it barked pretty good swinging the Cox grey 5x3 prop and 25% Cox super power fuel.




A few pictures of the latest design.

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.

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.

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.

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 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

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 ?

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.

I will test one and report via a vid and performance results.
PM sent, look forward to it thank you Jason.

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