fireman7875

My Feedback: (7)

Believe it or not I am dealing with my first TD .049 right now. I put a APC 6x3 prop on and filled up with 35% nitro and fired it up. Ran good but wasn't turning but 13,500 rpm. That seems kinda low to me, what about anyone else? Also, will that be enough to haul around a 24 oz airplane with some amount of authority?

SST

My Feedback: (2)

While I own a few APCs, I'm not a big fan, as I think they're overrated. My own opinion is that the very best 1/2a props are the (more rigid, but kinda fragile) Cox grays, followed by the (much more durable, but slightly less efficient) Cox black nylon. I think a 6X3 is a tad much for a .049, and is better suited to an .061. I have a Norvel .049 flying my Ranger 42. It does quite well (16,500) with a Cox black 5X3 & 25% nitro. I haven't weighed it, but with full-size radio & servos, it must weigh at least 24 oz's. BTW, I had one 25 years ago that would ROG on a paved runway and fly with a Cox reedie! Your 35% fuel should be fine if it uses at least 50% castor in the lube, as Cox motors like a little more nitro, but small motors in general don't do well on 100% synthetic lube.

Tim Wiltse-RCU

Brian,

Hum that's wacky stuff. Something sound amuck there! What fuel are you running. I am not a fan of anything other than 100% straight castor in a Cox( the ball socket will love you). Being a TD you may be able to use something different I just have not run tons of TD's. What head are you using? A Norvel head will fit and works well on a Cox .049/.051. Does it run solid when it is running? A Cox TeeDee .049 should be able to turn a black 6x3 at 18,000 without breaking a beat! Try a 5x3 and see I guess. They turn these little suckers up to 23,000 plus in racing. A Cox TD can turn bigger wood than a Norvel can and still be happy. Just make sure that the engine is clean, no cylinder varnish, the venturi jets are clear etc. Once she's happy she'll sing to you!

Later,
Tim

Lynn S

Try a 5x3 cox prop and see how it runs. I've got one that I buried the engine up to the fins in the ground and the blades just sprang back to their proper place. Your engine may be overheating with that much nitro. Try a standard glow head or lower nitro fuel.

Tim Wiltse-RCU

35% nitro is kids play for a slick TD .049 if it was 60 % them maybe.

Later,
Tim

gcb

fireman,
You didn't say whether the TeeDee is new or used. If it is used, it may not have the TeeDee glow plug. As mentioned previously, a Norvel plug will fit. Also a Nelson plug will work well.
Check that the ball-socket is tight. It may need resetting. You may have to reset often with 35% nitro and smallish (high RPM) props.
I run 6x3 and 15% nitro in mine, but I'm not racing them.

George

DICKEYBIRD

13500 is low, even with a 6x3, somethin's wrong somewhere.

In most cases, a stock Tee Dee (hi comp. head) with only 1 head gasket won't like a 6x3 on 35% at low to medium density altitudes. OK way up high like Denver or whatever. Put on a few extra head gaskets or put on a reedie low comp. glow head. 60%? Ya better put on a widdy biddy prop to get the revs up to the point where pre-ignition isn't occurring or she's gonna cook....real quick!

That's the way they run for me, in day to day sport flying....your mileage may vary.

fireman7875

My Feedback: (7)

Guys, I think I am about to feel real stupid! Here's what I think may be happening. I set up a test stand for the engine and used a 2 oz tank. Naturally the tank has those medium size fuel lines which don't fit too well on the fuel nipple on the engine. So to "fix" the situation I stuck a piece of 1/2a fuel tubing in the end of the medium line as sort of an adapter. So I think the medium tubing is squeezing the 1/2a tubing just enough to limit fuel flow. Obviously, the fuel line isn't totally occluded but it may be starving the engine. How does that sound?

Also, the engine is used, it does have a TD high comp head on it and my fuel is Sig Champion 35% with 20% oil (1/2 castor, 1/2 Klotz). I have a Cox QRC also with a 6x3 prop and I can tell just by the sound it is turning higher than the TD is.

I'm gonna change that fuel line and see if that fixes the problem. I'll let you all know what happens.

Dukester

My Feedback: (31)

Don't feel bad, we all do things like that. I finsished up my LS150 last week and was using an baby bee on a product backplate. So I get the engine mounted all nice and neat and go out side to start her up. I flip my dang fingers off and just can barely get it to run. After 1/2 hour of messing around (checking glow head, fuel lines, etc) I finally realize I forgot to put a spacer behind the backplate and the venturi was touching the firewall. A*****gly enough you need air to make combustion!! Go figure.....

Duke

fireman7875

My Feedback: (7)

Well I wish I had a nickel for every time I've tried to start an engine with the needle valve closed!

Last night I changed the fuel line to some tighter fitting medium size. It actually stays on the fuel nipple to the engine. So today I was anxious for the sun to break through the clouds (so my tach would read) and test the engine. It finally cleared up and outside I went. .........drum roll...............18,300 rpm on the tell tale little meter! So I have overcome my stupidity to discover the solution to a problem. Considering the TD now turns a 6x3 as fast as my Norvel .061 turns a 5.7x3, I don't think that engine will have any trouble pulling the Jr. Skylark I am about to build.

Thanks for everyone's help!

Tim Wiltse-RCU

Holy about to be flamed by Norvel lovers Batman!!!!


To think that a lowly little Cox can turn bigger wood than a Norvel.. Cox Rocks!!!!!!!

Is the Jr. Skylark a Early RC Models kit? I love the pictures Bob has of your planes. I dream of being able to finish as well as you do.

Later,

Tim

fireman7875

My Feedback: (7)

Whoa! Let me head that one off right now. I am a Norvel lover. However, I also love Cox's. Yeah yeah yeah I know, oil and vinegar, apples and oranges, Duke and Carolina and all that but hey; can't we all just get along?

Seriously though, the TD does turn that 6x3 as fast as my Norvel .061 turns a 5.7x3 (both APC's). But in the Norvel's defense, it is a throttled engine and the venturi is choked down a little bit to make it idle basically like Dickeybird does with his throttled cox's. I wonder what a CL version Norvel would turn that prop at.....?

And finally, yes Tim, that is an Early RC Models Jr. Skylark. Tim, I have seen your planes too...not exactly shoddy work. Thanks for the kind words though.

Andrew

46,850

the "other" andrew

Andrew

Cox Rocks!!!!!!!!! then Knocks@#$%# then ............ Silence as piston and rod part company.

Sorry Tim -- I couldn't resist.

the "other" andrew

Tim Wiltse-RCU

Andrew don't make me come over there

Later,
Tim