Mode Zero

Has anyone fitted a throttle to a Mills 1.3? We tried an old OS Max 10 throttle one of a club members made an adaptor for but in the fully shut position it still ran at about 1/2 speed. Has any one come up with a successful affair?
Im having so much fun flying a Simplex with Mike K's Arduino emulator I'd like to add throttle. Also having fun with the Tyro and Modelair Hummingbird using a revived RCS Guidence TX with one of Phil's emulators.Im reliving 1966 - 1970!

Cheers

John

Hi John

Good to hear you're enjoying flying S/C and reliving your youth!

I tried fitting a throttle to my MK1 Mills 1.3 many years ago (around 1990?) and I had the same experience as you, it was OK flat out but around half speed with the throttle fully closed. The club engine expert explained it was because the Mills MK1 has sub-piston induction, where the bottom of the piston goes up beyond the exhaust port and enough air gets in below the piston to keep it running. The only way to throttle it would be to have some form of throttle-linked exhaust restrictor like many early R/C glow engines employed or choose an engine without sub-piston induction. As it happens most Mills MK2 (and the latter Indian, Irvine and Boddo Mills etc) don't have sub-piston induction and work OK with a throttle, so I bought a second hand MK2 and used the modified OS 09 Pet carb. It works as well as my R/C ME Snipe, which means adequate but not brilliant... And as a bonus the MK2 is noticeably more powerful than my MK1.

Cheers Mike

Have you tried a PAW throttle? I've got a couple of throttled PAW 1.5cc motors and they throttle superbly. It maybe that a glow throttles isn't suitable for diesels. Certainly the PAWs have a very small choke area compared to a similarly sized glow.

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Pete

I think Alex 'Red' Phin sells throttles too.
https://www.redfinengines.com/product/r ... r-049-030/

Stew wrote: ↑26 Mar 2022, 16:33 I think Alex 'Red' Phin sells throttles too.
https://www.redfinengines.com/product/r ... r-049-030/

Get 'em while you can....
Gary

Is Alex stopping production? Oh man, are they made in Ukraine?

I agree with Mike_K, it's all to do with sub-piston induction.
I have a Mk2 with sub-piston induction (SPI) and it doesn't respond to the throttle very well at all.
I also have a Boddo version which doesn't have SPI, so should respond much better to the throttle, but unfortunately the inlet port is a different tapping size so my R/C throttle won't fit
So, I'm in the same situation in not having a Mills 1.3 with decent throttle control.
You can check to see if your engine has SPI by carefully looking through the exhaust ports as you slowly turn the engine over top dead centre. In the engine has SPI you will see daylight under the piston as it goes over top dead centre.
Barry

SPI is the reason why most early Cox/Tee Dee will only throttle properly with an exhaust throttle.

Stew wrote: ↑26 Mar 2022, 17:31 Is Alex stopping production? Oh man, are they made in Ukraine?

By all reports, the factory has been levelled.

Thanks for all the replies to my problem.
Just had a look at the Mills and sure enough it has sub piston induction. That explains why we had the same problem using the max 10 carb on a MkIII works modified Ollie Tiger. The effects of SPI on a throttle are something I had not considered.

Thanks again for all your help

John