TERBObob

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ok . got a goodie here .
I have been contemplating on taking a 049 COX and converting it to throttle control , but for exahust side ,rather than intake side .
Now ,my plan is this ( please throw in your comments and let me know - naye , or yay )
I am gonna put a 'sleeve" over the exhaust holes and make it a slider that will move up or down ( via a control rod hooked to a servo ) which SHOULD act like one from the older style nitros that had exahust restrictors , or throttles , on them .
Now , my question is , has anybody done this before ? and if so , can you give me any pointers and suggestions ?
my little guy ( 9 years old ) wants me to use a new 049 I have just laying around and put it on a airboat for him . But , I also want it thottled rather than running full bore , or not running .
So ... any pointers or suggestions ?
What I have planned , is it feasable ?

Selph-Inflicted

Never done it. The engineering is possible, not sure how or if it will work or not. Try it and see. Never hurts to experiment.

A few questions....
Wouldn't closing the exhaust will running full bore maybe want to flood the engineor cause a back up of fuel in the muffler? Would the response be there when you cranked back into the throttle? ...just some questions that I can come up with.

Just coming from a different direction....What if you made a trim tab connect to the throttle, when you deacceleerate the trim tab would angle down creating drag. The more the angle it moves the more drag it creates. It wouldn't be fesiable for land but possibly may work on water.


That's a good idea and theory. Keep us posted on what your discoveries are.

TERBObob

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Ok Chris ....
lets see ... wihout assuming , ahve you owned any of the old style , say , like KB 's where the throttle was a straight run venturi and even though it had a item that looked like a carb , was not , but rather just a venturi with a linkage that looked like it controlled a barrel carb , but in reality , it control the blockage / opening of the exhaust ?
theoretically , the exahust controls more of the intake of the engine , then the carbs intake does .
hard to describe , but hopefully , someone else who runs an older stykle engine can pop in . ( believe it or not , IMO - those older exhaust controlled engines , seemed like they hit a LOT higher RPMs than the new ones do AND also seemd a LOT more responsive ... ( but then , it could also just be my old memory .... )
Also , LOVE the idea of the trims slowing the hull down ... GREAT idea . Think I might try that one anyway on a different hull .

Selph-Inflicted

Terbo,

Never onwned one of the said that you mentioned. ....maybe I'm not thet old! LOL

Looking forward to learning something from this thread. I'll stay tuned.

playtime56

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Hi Terbo,
Assume this just something you want to do to exercise your skills, since exhaust throttled .049's are available. Right? I figure you already know that, BUT, you know what they say about "ass u me"!!!! lol Best to ya!!!'
Gordy

Tim Wiltse-RCU

TERBO,

Cox, ACE and maybe others make/made a throttle sleeve that fit over the cylinder and rotated via servo. They take alittle off the top end and slowed the engine down some. Not really a "true " throttle. Some sleeves worked better than others as it was a case of whether or not you got a good fit with your cylinder. There have been some good working throttle systems made over the years. Most all are one off set-ups that guys made theirself. To really throttle a Cox engine you need a combo of exhaust restriction and fuel metering i.e. carb. The ONLY Cox .049's that had a carb was the RC 05's and they are pretty rare theses days. There was the Cox Medallion that had a neat throttle that used a exhaust slider on it. I have only seen a few of these around as the are again rare pieces.

mgimel

TERBObob,

I'am in the process of resurrecting an airboat I built back in the late 70's. It has a Cox Golden Bee 049 with throttle sleeve, 2 channel radio. The boat is 18" X 8", nothing fancy, but was fun to play with.

TERBObob

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Any chance of getting a couple of close up pics of how its throttled ?
Thanks

Tim Wiltse-RCU

Terbo,

Here is a pic of a Cox/Ace throttle sleeve.

Later,
TIm

TERBObob

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Thanks .
Thats kind on the terms that I was thinking and am making ... but mine won't have the thingy that looks like a snap ring , which is what I assume is for the servo linkage ??

mgimel

I will try and take a shot of the motor with my webcam tonight and post, don't have a regular camera. Basically had a nyrod coming out of the transom and arching up to the top of motor pylon. Air rudder did touch the cable, but didn't seem to cause any binding or problems.

mgimel

Here's the photos, hope they help. The sleeve with the "RED" arm, I believe came from an old Cox car or van motor. Sorry about the poor quality.

Proace

Just my two cents here: Would an AP or Norvel >049 be an option? More torque per RPM and throttled.
Otherwise as I do recall the throttle sleeve was mainly used on Cox Tee Dee's with the dual ported and the Killer Bee straight sleeve cylinder.

brother

Hey Bob, I had an .049 that had exactly what you are describing... the only difference is that the sleeve rotated on the piston barrel. I no longer have the engine so I can't send any pic's. All I can tell you is that it worked. Oh and the opening on the sleeve was the same size as the exhaust port.

eas___1990

do they still sell these .049 with the throttle sleeves?

Ron Olson

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I have one of those exhaust throttles stashed away in a box of old Cox and OK Cub motors. I don't remember ever using it as some of the stuff was given to me by people that knew that I was into these kind of things. I'm going to do some work later on in the basement, I'll see if I can find it.


BTW, you guys are giving me the urge to build an airboat to mess around with. One LHS has a NIB O.S. .15 for $35.00, I have an extra radio system and a pile of foam board dying to be used. I bought a $150.00 foam cutter that is collecting dust.

TERBObob

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See that RON ,
Now you can put that cutter to good use
only problem I for-see [&o]


you build LOTS of them dude .... your GETTING hooked ....

eas___1990

uh oh ron is getting the fever

Ron Olson

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It would be nice to run on all of this firm water all over my yard.........

TERBObob

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It is , but when it gets like it is here , then its not as much fun . ICE ... when the temps go so low that the snow then becomes nothing more than white ice . Crispy , crunchy and a "fun' thing to run on .... talk about hard to control ....

( where is spring ? [&o][&o][&o][&o] , or even just fresh snow ? )

eas___1990

i am in favor of fresh snow(we gettin it right now) i think i am gonna have to down size on engine size on my boat though...gonna have to drop to prolly the gms .32,the thing looks strong 2000-20000 and 1.2 bhp at 18000 http://www2.towerhobbies.com/cgi-bin...?&I=LXDXL3&P=0

TERBObob

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Very choice selection . GMS engines are good . Although I , myself , prefer the dykes ringed ones over the ABC ones . But , all in all , VERY good engines for the money . Smooth idel , fast acceleration , and consist power . ( not like some Thunder Tigers I have owned ... [&o] )
Hey , you say your getting snow right now ? Toss some up here ... at least just a dusting would do ...

Ron Olson

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Bob, you've got a PM. You should have made (or maybe not) a trip up here this week, temps in the 50's then dropped like a rock to the teen's. The fog was terrible during the heat wave as evidenced by the 100 car pile-up on I-69 east of Lansing. 3 were killed in the mess. Roads went from wet to a skating rink. We've got snow again.............

TERBObob

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Yeah , I know ... its been the same here , just we got it a couple of days before you . The fog , the zero visiblity , the REALLY bad driving conditions ... ( hey , wait a minute now .... you didn't want ME in that 100 car pile up , now did you ? only kidding ... )
yeah , weather has been REAL screwy here lately . Now , we're SUB zero and thats NOT with the wind chill either . ( - 12 today , and tonight COLDER still )

eas___1990

man you guys got it pretty bad (watch out bob rons got it out for you...jus kidding) ya its comin down semi good,if i could blow some up there i would but the big bad wolf would even have trouble with that task