Throttle control for Cox .010 "Viking" engine.

Nice work Mauricio.....and an interestingly different approach. somewhere in my archives I have an Aeromodeller Annual article on exhaust restrictors for Cox engines...probably dating to the mid 60s or thereabouts, on home made restrictors to reduce power for trimming. IIRC there were construction dimensions for all sizes of Cox....including the orifice hole size....which might relevant to your efforts...

ChrisM
'ffkiwi'

Fantastic accessory, Mauricio..looking forward to your test stand video..how do you add the ring to the cylinder if the skirt on the cylinder base is not removed?

Thanks guys, any information you can provide is welcome, thanks in advance!
András, the exhaust chamber hugs the base of the crankcase, that is to say the lip that the crankcase has, which is practically equal to the diameter of the cylinder skirt, at the top, the first cooling fin is in charge of making the final pressure on the exhaust chamber, a custom-made washer can be placed if necessary, but if the measurements are taken perfectly, it will work correctly.
Detail: on the back of the chamber, you will see a threaded plug, this is to place a pressurizer, but apparently, it is not necessary.
You can see the video here, I am very surprised, it really works haha, it works! I can't believe it!!! I LOVE THIS FORUM.
If you are really interested in making it, I have no problem passing the measurements of my .010 VIKING Controller!

WOW It throttles really good better than most the exhaust throttles i have seen very quick! Job well done !

This is amazing, Mauricio! And thanks for the clarification about how the throttle chamber mounts on the cylinder...

Clever design

Beautiful engineering and craftsmanship Mauricio!!!…. Producing and working with parts this small is very challenging…. It works perfectly…. Not very often achieved with the .010 attempt to throttle…. Do you have an certain airplane in mind for it?

balogh wrote:This is amazing, Mauricio! And thanks for the clarification about how the throttle chamber mounts on the cylinder...

Thanks to you Andras. There really are no losses, but for that, machining must be done with a digital caliper, that way the precision is much more secure, at least in my case.

getback wrote:WOW It throttles really good better than most the exhaust throttles i have seen very quick! Job well done !

Dear friend Eric, thank you for your message. It really works. I must say that I was anxious while making the parts, since I have no references of real measurements necessary for the proper functioning of the engine.
I based myself on the principle of the throttle ring, taking into account the exit surface of each exhaust port and so I planned this design. Of course, maybe it can go better if other measurements are tested or maybe not, but I am already very well with this throttle, it perfectly meets my expectations.

Levent Suberk wrote:Clever design

Thanks Levent!!...many years ago I saw something on the internet about a Pee Wee .020, I don't remember if it was an engine on ebay and had an accessory, something similar to this, but I never found it online again to compare and take some safety reference. So with that fuzzy image in my mind, plus the experience of the exhaust chamber I made for some of my engines, seeing that it can be made perfectly sealed (without leaks) and that by covering the outlets the engine even stops, then I put together the idea and this is what came out.
Thanks again.

rdw777 wrote:Beautiful engineering and craftsmanship Mauricio!!!…. Producing and working with parts this small is very challenging…. It works perfectly…. Not very often achieved with the .010 attempt to throttle…. Do you have an certain airplane in mind for it?

Dear Roberto... while I was making my throttle I took a picture that reminded me of you, I'm serious. You do a lot of handcrafted work and this picture I'm sharing here, making the valve cams out of bronze sheet metal, in the early hours of one of these days, reminded me of you.
I don't have any particular model in mind right now. This is because there are many Cox cylinders with the skirt at the base, which means that a throttle ring cannot be placed, unless it is by a split sleeve and an upper ring, or by turning the cylinder itself, etc. This solves that point for these cylinders with a skirt and can be made for all types of displacements, that's great, from .010 to whatever you can think of, just by enlarging the scale, of course.
A hug dear friend!

just came here from you tube video, Very nice mod indeed, i think i will 3d design and print one to test fit first and then make it on the lathe but for a 049, it is a good way to redirect all this oil messing the models.

ffkiwi wrote:Nice work Mauricio.....and an interestingly different approach.  somewhere in my archives I have an Aeromodeller Annual article on exhaust restrictors for Cox engines...probably dating to the mid 60s or thereabouts, on home made restrictors to reduce power for trimming. IIRC there were construction dimensions for all sizes of Cox....including the orifice hole size....which might relevant to your efforts...

ChrisM
'ffkiwi'

I would pay millions to see that article Do you think you can dig it out?

Thomas

Gordinir8 wrote:

ffkiwi wrote:Nice work Mauricio.....and an interestingly different approach.  somewhere in my archives I have an Aeromodeller Annual article on exhaust restrictors for Cox engines...probably dating to the mid 60s or thereabouts, on home made restrictors to reduce power for trimming. IIRC there were construction dimensions for all sizes of Cox....including the orifice hole size....which might relevant to your efforts...

ChrisM
'ffkiwi'

I would pay millions to see that article Do you think you can dig it out?

Thomas

I'll have a fossick around for it this weekend

ChrisM

I like this design this way the valves can be placed in front of the exhaust ports on the cylinder the fact of using two valves instead of one must help not to lose performance I know from experience that an exhaust control is very efficient And I believe that this one must be very good and that is what the video demonstrates with my car I only use one valve but seeing this system inspires me. But for me it is the quest for performance and the development of a noise reduction system that led me in a direction but Mauricio different approach inspires me. The cox cylinder has two windows on the cylinder and all this is really very logical to have two valves or even without using two valves an exhaust manifold with two outlets is preferable and I believe greatly reduces the effect of loss of performance due to exhaust gases recirculated by the spi This is a great invention my friend, thanks for sharing the results.