Different needle settings

Michpatriot Sat Jan 28, 2023 6:18 pm

Hey all! Tonight I switched out the plastic backplate for an aluminium version. When I tried starting it with the new aluminum backplate it was a head scratcher for a while until I figured out the new backplate needed three turns+ richer to get it to fire up...5-1\2 turns from seat to its happy tune..do the aluminum backplates use a different shaped needle? It runs good but just a little odd the differences between the two.

Joel

Michpatriot Sat Jan 28, 2023 8:11 pm

Side note..the overflow on the bottom of the aluminum tank was gonna get buggered and bent hanging out of the bottom when using it on a Man-Win trainer.. And the aluminum backplate had a vent..so I got rid of the problem using Tig weld..

HalfaDave Sat Jan 28, 2023 8:42 pm

Hi Joel,

Every Cox needle valve, has it's own personality, there is no, #s of turns out, as far as I know...
Respect,
Dave

P.S. How can you fill that tank?

balogh Sun Jan 29, 2023 12:34 am

COX needle valves came with several Threads per Inch = TPI design. Your metal backplate must have a fine thread needle valve version incuding 80 and 128 TPI, hence the more turns it needs for the peak engine speed..

https://www.coxengineforum.com/t15413-thread-of-needle-valve?highlight=Needle+valve+threadp

You can rotate the backplate and tank by 90 degrees thanks to the 4 mounting screws, so the tank vent and needle valve can be placed in any horizontal or vertical position when the cylinder hangs inverted.

Michpatriot Sun Jan 29, 2023 8:31 am

HalfaDave..the new aluminum backplate has a vent hole next to the needle valve allowing me to plug weld the original tank vent..I was concerned with belly landings bending it and or cracking the tube at the tank causing a leak, not to mention getting plugged with dirt.

HalfaDave Sun Jan 29, 2023 11:03 am

Hi joel,

I get it now, you have a Babybee metal back plate, all is good. Smile

If you think the needle is loose/leaks, put 1/2in (15mm) of fuel tubing over the spring/needle. It will seal, work.

The original Man Win was built by a fellow Canadian. The night before an event.
To teach young kids to fly a few laps. It worked.
The engine out thrust, and line rake was meant to slow it down, and keep the lines tight.
It worked, and the internet took over.
It flies nice level laps, as it was designed.

Take care,
Have fun,
Dave

Michpatriot Sun Jan 29, 2023 12:54 pm

Good to know its a good trainer! I'm going to try it out with my four girls.

HalfaDave Sun Jan 29, 2023 2:38 pm

Hi joel,

If they want to start racing each other... look out ! Smile

Enough fuel for 4 or 5 laps is perfect to start.

Does not take long until they can get a full tank through it.

The best instructor here, made a big deal about safety(obviously)...

Did the 'very important' test flight, 4 laps and crashed it right in front of them. (every time, he was very good ! )

Picked it up, dusted it off... the fear of crashing was gone.

That was when the line ups grew....

Take care,
Have fun,
Dave

Michpatriot Sun Jan 29, 2023 2:54 pm

Lol gonna be a Circus McGurkus for sure! I can't wait.. it'll be great when I get the second one finished and both in the air. This one here is a mix of parts..the tank is from the ill fated venom2 that tossed a rod on the third or fourth tank during break in.. The crankcase and crank were an e bay purchase as well an another eBay piston and cylinder..a little lapping and fitting add a touch of weld and a aluminum backplate..

she's buzzing along happily waiting for a nice day! I've got parts and pieces coming for a second trainer engine that will hopefully be running in the next week or so.

Michpatriot Sun Jan 29, 2023 3:17 pm

I'd also like to find a youvenko style 1\2a wing similar to the .25 size one I have..can't afford to order 10 of them like the combat guys do although.

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