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Post  Gordinir8 on Thu Aug 06, 2020 3:42 pm

So guys i am new to this forum although i know this page for quiet a long, just want to say hi to everybody here and ask a few things. I want to know if the throttle sleeve that limits the revs of the engine is actually bad for the engine or is it ok to use it. Same applies for muffler that i am thinking to put alternative in order to limit somehow the oil spread, i have one of those new build mufflers that are available today. Also my black widow is missing the little intake filter screen, is this a problem besides that something can be sucked in or it might affect performance like excessive fuel consumption. I think that my engine operate for less than two minutes but i haven't fully test it yet. I am about to fly my new build Qtee and that will be my first time that i will fly a cox powered rc plane besides CL i used to fly when i was younger. First flights will be without throttle control but i would like to try one later.
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Post  happydad on Thu Aug 06, 2020 8:51 pm

Gordinir8 wrote:So guys i am new to this forum although i know this page for quiet a long, just want to say hi to everybody here and ask a few things. I want to know if the throttle sleeve that limits the revs of the engine is actually bad for the engine or is it ok to use it. Same applies for muffler that i am thinking to put alternative in order to limit somehow the oil spread, i have one of those new build mufflers that are available today. Also my black widow is missing the little intake filter screen, is this a problem besides that something can be sucked in or it might affect performance like excessive fuel consumption. I think that my engine operate for less than two minutes but i haven't fully test it yet. I am about to fly my new build Qtee and that will be my first time that i will fly a cox powered rc plane besides CL i used to fly when i was younger. First flights will be without throttle control but i would like to try one later.

Gordinir8: First welcome to the CoxEngineForum. I Love This Forum!  

1. The throttle sleeve when closed will affect the engine exhaust, so logically it should affect the engine performance, but how much? some people think it affects performance a lot and some think a little. I think it depends more on your entire engine setup than anything. with the throttle wide open, some throttles have a round hole, still limiting the exhaust, while some have a large slot equal to the exhaust port, so the effect is small. If there is also a muffler, there is a throttle-muffler speed control, then the effect will be more due to the limiting of the exhaust gases, to quiet the noise.
  With the throttle partially open the effect will be limited by the size of the throttle slot or hole and the amount of throttle. Some users say that there are issues with maintaining low speeds consistently. I used a muffler on a babe bee years ago because of noise restrictions and had no issues with RC loops and axial roles. the planes demise was when I tried to do some kind of figure 8 where you have to come out of a roll inverted and i planted the plane in the dirt. the engine was o.k., but the plane took a while to repair.
2. Mufflers - the amount of goo coming out of the muffler depends on the muffler. In the old days there was a car muffler cast as one piece, with a long neck, directing smoke and goo away from the car, not adjustable. It is very hard to get, but available thru our favorite vendors sometimes, (ref. Matt at  exmodelengines.com and Bernie at coxengines.ca). Another was a 3 piece similar to the long neck version, but shorter and spring type adjuster on the size of the exhaust port. The current  model is similar to the older model, but does not have the nose, to direct the gasses away and has a small hole instead of a large exhaust area.
3. the filter on the intake of the fuel tank, Black Widow can be purchased from the previously mentioned vendors. the one purchased may be slightly larger, but it can be trimmed. the forum is like google. search in the search box what you need to know, like "how do i put screen over fuel intake on Black widow" and you most likely you will get a post or posts that will describe or show a video how to do it.
4. 2 minutes run time - try searching that subject. or look at the location of the pickup tube. It could be placed too high in the tank and not empty the tank, or look at the tubing in the fuel pick up area for clogs or debris. Two Cents

I hope I answered your questions.

ask questions and someone will answer them, eventually.

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Post  Admin on Thu Aug 06, 2020 10:04 pm

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Post  GallopingGhostler on Thu Aug 06, 2020 11:48 pm

Gordinir8 wrote:So guys i am new to this forum although i know this page for quiet a long, just want to say hi to everybody here

Welcome to the forum! Thumbs Up

Gordinir8 wrote:and ask a few things. I want to know if the throttle sleeve that limits the revs of the engine is actually bad for the engine or is it ok to use it.

Exhaust throttles work fine on the Cox engines, very reliable, simple. Response is non-linear. 1/2 throttle is about 1/3rd opened. I've used these on a Golden Bee and my R/C Bee used an exhaust throttle muffler. You lose a little top end with the muffler, but not much. The R/C Bee and most of the later Cox .049's don't have SPI (sub-piston induction, that gap between bottom of piston, the skirt and exhaust port bottom edge. This gap allows a puff of fresh air into the crankcase air fuel mixture to boost power.)

You lose some horsepower when you muffle engines that have SPI, because instead of fresh outside air entering, you have inert (oxygen-less) exhaust re-entering the crankcase, diluting the fuel-air mixture. However, engines with SPI work fine with a mufflerless exhaust throttle ring.

Gordinir8 wrote:Same applies for muffler that i am thinking to put alternative in order to limit somehow the oil spread, i have one of those new build mufflers that are available today.

Personally, the small amount of unburnt oil mist that gets deposited on the plane has never been a problem with me. A shot of Fantastic cleaner (or equivalent) on the aircraft surfaces with a paper towel wipe down is sufficient for me. These engines don't put out the quantity of exhaust spooge that a larger engine puts out. Also, best muffler that is lightweight tends to put out the exhaust around the circumference of the cylinder. So, you really don't gain much adding a muffler unless you want to diminish noise output.

Gordinir8 wrote:Also my black widow is missing the little intake filter screen, is this a problem besides that something can be sucked in or it might affect performance like excessive fuel consumption.

It's not a problem most of the time, unless you are flying into dirt. Even then, if engine is stopped immediately upon hitting a dusty dirt spot for "landing", being the intake in the back, more or less I found not a problem. I just squirt fresh fuel behind to flush out any dirt. Basically, use your judgment. Sometimes I've removed an engine in the field, disassembled and flushed dirt away from the back with a shot of fuel. Reassemble.

Gordinir8 wrote:I think that my engine operate for less than two minutes but i haven't fully test it yet. I am about to fly my new build Qtee and that will be my first time that i will fly a cox powered rc plane besides CL i used to fly when i was younger. First flights will be without throttle control but i would like to try one later.

With the .049 reed valve engines, in general you won't see much difference in speed between power and glide. Throttle is nice (I've used it on my Q-Tee), but not essential. Even the late Lee Renaud, designer stated that in his instructions for the Q-Tee. I flew mine on 2 channels using a Golden Bee. Also flew it on single channel rudder with auxiliary throttle using an aftermarket Ace R/C throttle sleeve. OTOH, I have flown mine with a .061 Norvel Big Mig. That engine has a bit more power for real fun, so there will be a difference in power versus glide.

Good luck on your Q-Tee test flights and maiden. I know you will have a blast with it even on 2 channels.
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Post  Gordinir8 on Sat Aug 08, 2020 12:55 am

Ok guys thank you I will order a sleeve to give it a try and see how it goes.
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Post  happydad on Sat Aug 08, 2020 1:40 am

Gordinir8 wrote:Ok guys thank you I will order a sleeve to give it a try and see how it goes.

Gordinir8:  I had a little trouble with the website. It seemed frozen for a couple of minutes.

Before you order, someone on the forum may have an extra throttle sleeve.And the sleeve is usually matched to the cylinder for a “tight” fit to keep exhaust gases from leaking out the sides of the sleeve. The are sold in sets too, but PM me. I have several extra, it depends on which cylinder you have or want too. If it is a TD, then I do not have a spare, all throttle sleeves are in use.
I have #2, #3 with dual slit and #3 with wide exhaust slot.

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Post  Gordinir8 on Sat Aug 08, 2020 4:22 am

Thanks for letting me know.
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