Re: CEF .020 Horseshoe Backplate

1/2A Nut Sat Sep 21, 2019 1:03 am

Cool beans Bernie do you have a pic of the die cast design?

Small Cox Logo

Tee Bee Sat Sep 21, 2019 7:03 pm

I snagged one. Thanks! Order 00W50682UF885354F

Troy

Marleysky Sat Sep 21, 2019 7:43 pm

Just got mine in the mail today! NoW, off in search of a 128tpi needle valve assembly.

Cox International Mon Sep 23, 2019 12:57 pm

Basically looks like the .049 version, just .020 size and the reed retainer seems to be of the "flanged" type, like Golden Bee / Black Widow but one can surely modify the setup to take the "circlip"; as those are readily available.

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**944_Jim** Mon Sep 23, 2019 5:40 pm

Got my two. Man, that was fast!

And they are so cute, too! I bet they look sweet next to a 1/4 ounce tank!

Jason_WI Mon Sep 23, 2019 6:13 pm

Looking forward to seeing on feedback on these backplates. Good or bad. Don’t hold back.

**944_Jim** Mon Sep 23, 2019 6:22 pm

Jason, the venturi opening is almost in the same plane as the back face of the backplate. Is the intent to use some sort of stand off to allow air into the engine? Space the engine out with washers on each corner?

Or will they get enough air just flush-mounting the engine to the firewall?

Jason_WI Mon Sep 23, 2019 7:20 pm

944_Jim wrote:Jason, the venturi opening is almost in the same plane as the back face of the backplate. Is the intent to use some sort of stand off to allow air into the engine? Space the engine out with washers on each corner?

Or will they get enough air just flush-mounting the engine to the firewall?

There is .031" clearance to the bottom in the intake. In all my tests it was flush mounted to a pine board. Very similar clearance to a .020 helicopter back plate.

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**944_Jim** Mon Sep 23, 2019 7:46 pm

Thanks much! I'm excited to try these guys. Now to find a suitable twin!

1/2A Nut Tue Sep 24, 2019 11:53 pm

Thank you Bernie Thumbs Up

very interesting to peak into the past design aspects from the Cox team.

Thank you CEF Jacob and Jason!! Thumbs Up

lovely package with all the goodies to get the engine set up top notch well done!
My order came in I bought two backplates will bench this one as shown, plan on using turbo plug, bullet spinner
and throttle sleeve in the long run. For now want to get a base line read with the 4x2.5 speed prop.
Did have a 128 TPI needle valve assembly on tap so expect a good solid needle.

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Jason_WI Wed Sep 25, 2019 12:07 am

Brad,

That looks good. Can’t wait to see a run video.

Jason_WI Wed Sep 25, 2019 12:15 am

Today I revisited the 80 TPI needle valves. I built up 2 engines with reject backplates.

This first engine used a burred cylinder and piston set. I deburred the cylinder and removed some rust. Found a crankcase, crank, and drive washer. Added a starter spring and new glow plug. Assembled the backplate with a short 80 TPI needle valve from a product engine.

Using a black 4.5x2 prop and 25% Cox super power fuel it started right up with 4 turns open on the NVA. Took about 1/2 turn to find the sweet spot. Ran pretty well. Had to adjust the syringe up when the fuel was getting lower.

It’s about an 8 minute run.

The second engine used an existing .020 short block. I assembled the backplate with a long 80 TPI NVA from a SureStart engine.

I think the longer needle valve vibrating caused the varying RPM. It’s not bad though.

Same prop and fuel as the first run.

Here are a few pictures of the assembled engines.

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1/2A Nut Wed Sep 25, 2019 1:17 am

Turbo Killer Wizzer .020 Thumbs Up

- Carbon blend horse shoe backplate
- Large bore intake
- 128 TPI Needle valve
- Tee Dee Cylinder / Piston set
- Mylar performance reed valve
- Valentine bullet spinner
- Kamtechnik Turbo Plug adapter
- OS P4 gold turbo plug

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Full functioning 7.5cc clunk tank.
11mm long 1mm ID inner tank tube for full clunk flex and 1.5mm ID brass and silicon tube there after.
2.4" or 61mm total line length from clunk tip to NV nipple.

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**Admin** Wed Sep 25, 2019 1:33 am

Only 5 backplates left! Eyebrows

So perhaps a short 80 TPI needle could be used with decent stability?

Brad those look like some hot little engines! I too can't wait to hear how they perform. Beer Cheers

Tee Bee Wed Sep 25, 2019 4:06 am

I signed on for another one before they are gone. Thanks!

Order #9AX29782N6547535G

Troy

getback Wed Sep 25, 2019 7:52 am

Got mine the other day , they look amazing with all the stuff to get her going just watching you guys to see what nva is working best . I got some of both and thinking the aluminum one will work best , You engine looks great Brad bee listening for it Very Happy

1/2A Nut Wed Sep 25, 2019 6:34 pm

Tested the Killer Pee Wizzer .020

Modified Pee Wee into a little screamer.
3.8 x 3 / Peak 19,864 rpm / 57 mph pitch speed / .26w / 3.6 oz thrust
Kamtechnik turbo plug adapter / large intake venturi
Carbon blend horse shoe style backplate.
Valentine bullet spinner / 25% nitro
128 TPI needle valve / 3 shims

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Jason_WI Wed Sep 25, 2019 7:18 pm

Any trouble getting it to run? Your video is the first to show one running other than me. Looks like a screamer.

1/2A Nut Wed Sep 25, 2019 11:04 pm

No not a hitch with the way it's set up. I don't use spring starters
with .020 engines nor flip starting prefer the Hornet 1/2A E starter.
Once I found the needle it held rpm well.

getback Thu Sep 26, 2019 6:34 am

Sounds good Brad , i don't know what a standard PeeWee Rpms are but that is pretty impressive to me Small Cox Logo

1/2A Nut Thu Sep 26, 2019 9:45 am

Thank you Eric!
Yea it had 3 head shims brief peak hit 20k never seen a Pee Wee hit 20k static!
I have put a throttle sleeve on it and went down to 1 head shim going to test that next.
Hope to hold over 20k static even with a throttle sleeve.
This one is a treat to have on tap, I am calling it a Killer Pee Wee!

20k Cool

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batjac Thu Sep 26, 2019 10:54 pm

1/2A Nut wrote:Thank you Eric!
Yea it had 3 head shims brief peak hit 20k never seen a Pee Wee hit 20k static!

The .020 engine from a Cox Skycopter I cleaned up a few weeks ago was hitting about 20.5K static with 25% fuel. I didn't mess with head shims or anything to see if I could get more. Just the stock engine with a three bladed prop. I just love .020 engines. 'Course, I love just about any Cox engine.

What is your over-all impression of the turbo plug adapter? Should I order one? I've been putting off making an order to Kamtechnik for some reason. I guess I should make the order this weekend.

The "Not A Fighter" Mark

edit: I just looked at the Kamtechnik site and did not see a head for the .020 engines. Is yours a custom job?

The Confused Mark

Jason_WI Thu Sep 26, 2019 11:00 pm

Only 4 CEF .020 backplates left.

All the latest orders have been shipped out.

batjac Thu Sep 26, 2019 11:20 pm

Jason_WI wrote:Only 4 CEF .020 backplates left.

All the latest orders have been shipped out.

*SIGH*

Oh, all right. I just ordered mine...

The Easily Susceptible Mark

1/2A Nut Fri Sep 27, 2019 1:53 am

Mark yes the small dia. 3.125 x 2.5 3 blade prop can get over 20k with a good engine but not with the Cox 2 blade.
All my best efforts have not been able to bust 20k with the black 4.5D x 2P even using a TD .020

I am using a modified prototype turbo plug adapter, not sure what's going on with Kamtechnik
these days as far as testing .020 adapters. No further communication on Greg's end about it for
over a month now. I have this one set up with a throttle sleeve will run it up Fri. or Sat. using
1 head shim hope to hold 20k ish with a 3.8x3 prop. I need the 3 pitch for speed projects.
TD .020 spins this prop at 22.8k rpm with a Cox plug.

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