TD .049 SWEPT WING PUSHER BOOMERANG

TD ABUSER Sun Jan 10, 2021 11:26 pm

It's got about 100 sq inches and I think will end up weighing 8.5 ozs.
HS 56 servos for the elevons.
The prop is a recontoured 4 x 4.5 drone prop.
It should break the speed of light with the aluminum piston that just came in from Cox International..!!!!!!

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badbill Mon Jan 11, 2021 8:38 am

Nice work! Please don't get your face anywhere near that prop while the engine is running. Very unsafe.

gkamysz Mon Jan 11, 2021 8:41 am

I like it! How is the CG looking?

TD ABUSER Mon Jan 11, 2021 9:49 am

gkamysz wrote:I like it! How is the CG looking?

Thanks Greg and thanks again for those fantastic backplate mounts..!
What a difference they make to simplify and remove weight from our TD powered creations.
I think the correct CG is achievable without having to sin. The CG at the wing root is supposed to be where the elevon hinge line meets.

davidll1984 Mon Jan 11, 2021 11:52 am

Y read u want To use aluminium piston in that engine ? Y have one runing in m'y custom nickel plated cylinder wit rc ring in m'y litle tether cars tink in plane cylinder cool faster than the piston result. Lost rpm over heat bether modify piston inside skirt conecting rod lower part crank pin

TD .049 SWEPT WING PUSHER BOOMERANG 16103810

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TD ABUSER Mon Jan 11, 2021 2:26 pm

Are you saying I need a nickel plated cylinder...?

davidll1984 Mon Jan 11, 2021 7:44 pm

Its bether use them wit bras cylinder plated wit nickel crome Not easy To reproduction one try wit silencer help holding heat on cylinder bring rpm down help engine life if posible To build constant rpm engine Not the fastes wit them just m'y expérience its Not the best solution y try laping piston start wit litle lose fit start hard To explain y am french canadien sory

TD ABUSER Mon Jan 11, 2021 9:56 pm

davidll1984 wrote:Its bether use them wit bras cylinder plated wit nickel crome Not easy To reproduction one try wit silencer help holding heat on cylinder bring rpm down help engine life if posible To build constant rpm engine Not the fastes wit them just m'y expérience its Not the best solution y try laping piston start wit litle lose fit start hard To explain y am french canadien sory

Thanks David..I had a Canadian machinist [Andrew J Coholic] explain to me once why an aluminum piston would not work in the Cox Cylinder that is made out of Leadloy.

getback Tue Jan 12, 2021 8:34 am

That's a pretty wild looking design with the large fin and sweep back wings , i am sure it will bee fast ! A few of us bought the Alum. piston and rod (not assembled) from Matt at EX model engines sometime back Brad in Texas was the first I remember here to assemble on and try and it did not last long at all ! I wonder if you were to cut down the skirt and install in a non SPI engine to make SPI it would not over heat as quickly ? Huh...

getback Tue Jan 12, 2021 8:40 am

Here is the link as you can see he did alot of break in and i may have been wrong about how long it lasted ?! Surprised

1/2A Nut Tue Jan 12, 2021 10:40 am

getback wrote: Brad in Texas was the first I remember here to assemble one and try and it did not last long at all !

I tested the aluminum rod/piston below.
Still have it runs ok if left a bit rich. Can run with a 6x3
to keep the rpm down during break in.

Feb 25, 2019
Cox Aluminum Rod / Piston Bench Test Break In .049
3 short runs prior to this one. Will require patience with some rich
runs till fully broken in. The aluminum expands and it gets tight
if left to run at full throttle then shuts down as demonstrated.
Older worn cylinder would be best polished up to hone the piston.
Grish 5x4 used 25% nitro / 20% castor

Small Cox Logo

TD ABUSER Wed Jan 13, 2021 9:21 pm

1/2A Nut wrote:
getback wrote: Brad in Texas was the first I remember here to assemble one and try and it did not last long at all !

I tested the aluminum rod/piston below.
Still have it runs ok if left a bit rich. Can run with a 6x3
to keep the rpm down during break in.

Feb 25, 2019
Cox Aluminum Rod / Piston Bench Test Break In .049
3 short runs prior to this one. Will require patience with some rich
runs till fully broken in. The aluminum expands and it gets tight
if left to run at full throttle then shuts down as demonstrated.
Older worn cylinder would be best polished up to hone the piston.
Grish 5x4 used 25% nitro / 20% castor

Thanks for the warning.!
Hear it is painted with Klass Kote over dope that was used as a sealer. Tommorow I'll knock off the shine to give it that Deep Space dullness it's supposed to have.

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TD .049 SWEPT WING PUSHER BOOMERANG Img_0314

davidll1984 Wed Jan 13, 2021 9:43 pm

Y like the look of that model Thumbs Up

NEW222 Wed Jan 13, 2021 9:53 pm

Wow. That little think looks great and very quick just sitting there alone. Can't imagine how fast it will actually be while running.

TD ABUSER Thu Jan 14, 2021 12:08 am

NEW222 wrote:Wow. That little think looks great and very quick just sitting there alone. Can't imagine how fast it will actually be while running.

Government Agents in dark suits and sun glasses just showed up and confiscated the plane. So we will never know how fast it might have been..... Cool

1/2A Nut Thu Jan 14, 2021 4:41 am

Look forward to you abusing that TD Chuck!

Small Cox Logo

The aluminum piston is more of a side line fun project to get running.
Could lap the piston in to speed up the process until the top end can
be held. The engine I tested is very low weight. The aluminum rod and
piston helped to drop off the grams. Could use the engine on a .020
plane that needs extra power.

TD .049 SWEPT WING PUSHER BOOMERANG 20210110

Thrust bearings are possible with a pusher config. / might get 4mph ish on the top end.

TD .049 SWEPT WING PUSHER BOOMERANG Imag1611

TD ABUSER Fri Jan 15, 2021 7:03 pm

I've wondered if you can get away with removing the cooling fins. I figured Leroy Cox experimented with that.
I'm not sure but I think the early VA was the lightest .049..?

1/2A Nut Fri Jan 15, 2021 8:36 pm

I have the VA VKI and II one set up with a muffler hits 41g with a glass combat prop.

This has moderate fin action happening. Some CL efforts have taken
the same approach with higher nitro at speed they run plenty cool.

TD .049 SWEPT WING PUSHER BOOMERANG 20210111

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