Doc.316

Hey guys and gals;
I just built a la stick with a cox .010 on it. Went out to fly it today. Used 25% 1/2 A fuel with extra castor added. The performance was pretty dismal. Got it home and put it on a tach (17,000!) Wow I was amazed it flew. So I mixed up some fuel. 35% nitro 25% castor. Now it turns 27,500. I have a couple of questions.

1. What does an .010 normally turn. I know they say 30,000...but should I really be seeing this on a stock engine with the grey prop? Is the grey prop the only one avaliable?
2. It was running a lot more consistant with the more nitro..is there any other tricks to get a more consistant run with the stock tank? (I did the fuel tubing on the needle trick and this helped.)

Thanks for your time.
Steve

skaliwag

My Feedback: (1)

The TD .010 loves 33 to 35% Nitro... It will take more but will fry plugs for not that much of a gain.
Is yours a red or black plastic parts model or red? Is the case Gold?
I had one that tached at 32.3K!!! but doesn't do it any more.. 29k is its spot now.
I never worked on the black or grey prop deal... The gray ones break, the black ones don't.

MJD

My Feedback: (1)

27,500 is in the ballpark though not stellar. I'm not sure any of mine ever got to 30k on the stock prop. If you only saw 17k when you got home, it is no wonder the thing flew like a dog. And, whatever caused it to run so poorly would also explain any erratic running as well. Is this engine new or does it have run time?

As skaliwag said, 35% is a good .010 brew and more is a waste. It broadens the needle settings and the engine will run more smoothly as you've noticed. Have you flown it like this yet?

And you might want to grab a few props from one of those online Cox parts peddlers. Don't forget nobody has come up with an alternate plug that works that I know of. Pay extra careful attention to your glow driver, needle settings, etc..

MJD

ffkiwi

IIRC the instructions should quote 27,000rpm on the stock prop. On 30% nitro-which is the standard fuel around which the TD range were designed-you should be getting 27,000 on the std black prop. If you're not-you either have a substandard engine-or more likely a leak somewhere. The head could be loose, ditto backplate/crankcase joint, the plastic carb housing, venturi, or retaining collet. The plastic used did distort and embrittle with time.
Also take care to check that your prop is correctly balanced-an unbalanced prop will cost you a lot of rpm in this tiny size of engine. [easier said than done however-most prop balancing rigs are far too big for the 010 prop]. Speaking of which you ARE using the correct prop I hope-the Cox 3"x1.25" that should have come with the engine. If you were mistakenly using the larger 4x2.5 020 prop then 17,000 is about what I'd expect. Peter Chinn in his original engine test of around 1961-63 (depending on which magazine you read it in) got the engine up to 32,000rpm (and its estimated BHP peak) by carefully cropping the prop diameter in 1/16" increments-but assuming a 10% unload factor in the air, ground rpm of 27,500 would get you over 30,000rpm in the air anyway, so its probably not worth the effort unless you have a lot of spare props. But if you want to do the experiment go ahead-and let us know the result-it may not be as clear cut as expected-revs will go up-but thrust (which is what flies the plane after all-not rpm) may well go down.
As per the other replies, I would not go above 35% nitro-40% nitro puts you in the danger zone (with any Cox-regardless of size) where you can chew through glow elements very easily. Another point would also be to consider the possibility of overcompression-which can also make the engine hard to needle and set. After a test run and rpm check-see what effect adding another head gasket has-if the revs stay the same or go up-the motor was probably overcompressed (for the amount of nitro being used) Finally-is the liner varnished? If it is-that would account for low revs-as the varnish creates increasing friction as the engine heats up-the instructions tell you how to deal with this problem if it occurs.

'ffkiwi'

Tee Bee

Mine usually rev between 27k and 28k static depending on the needle tuning with 25% nitro and the black Cox props. I broke a gray prop on the first landing, so have used the black ones since. Make sure the tiny little holes in the needle assembly are clear as they tend to gum up over time. As already mentioned, make sure you don't have any air leaks. With 25% Sig fuel and extra castor, I've been getting long glow head life and consistent, reliable runs. As a matter of fact, my LaStick runs an old red-tanked .010 with the original head on it. I flew it at SMALL this year. These tiny engines are a blast! Good luck.

MJD

My Feedback: (1)

It's been ages since I tached one, but it occurs to me now that 27,500 is actually pretty typical. I don't remember blowing through plugs that often either, and I think in general the runs are so short it takes along time to accumulate enough time to trash the element. When you only run at full tilt boogie, you can get every last minute out of a plug.

On the subject of maximizing rare plug life, I'd advise against ever adding Armor-all to your .010 fuel.. ;-)

Mine always behaved pretty well on 25%, but your mileage may vary.

Black props are easy to get now, and not expensive. Good time to stock up. I bought 30 so I'm good for a while . But I also fly some .010 FF and have the occasional oops under power.

Any chance of some video? .010 vids are always cool - "find the mosquito".

MJD

DeviousDave

Mine typically run 27,400-27,500. They really respond well to playing with props.... I'm currently playing with an .020 prop that has been cut down. It's turning 29,000 and is noticeably faster than stock.

Doc.316

Hey thanks.
I got the Stick out with the new fuel and it was a different beast. I guess 10,000 off of peak does matter a bit... I actually got a loop out of it. I did bust the prop on the last flight. I had my neckstrap wrapped around the stick..launched her and tried to put in some aileron....well I guess I will have to make sure that the neckstrap is off.

I am not sure how much oil/nitro they put in the 1/2 fuel that I was using (It begins with Mag) and they won't say but I am guessing it doesn't have enough nitro or oil (wow it threw out a bunch more oil than the commercial fuel even with the extra castor I added). I guess the old cox fuel only was 15% wasn't it?

It seems that with the newly mixed fuel my .010 is running pretty typically and there is another .010 tearing up the skys...

Thanks for the info.
Steve

MJD

My Feedback: (1)

IIRC the Cox Super Power Fuel was 15% and Racing Fuel 30% nitro, and 22 or 23% castor. Someone may chime in with more precision but I'm sure that's real close.

MJD

Doc.316

Wow I had forgot about the racing fuel. It did have a better smell to it. (more nitro)

I guess I should add...this stick was just a test plane. When I was building I figured while I was geared up I would build 5 of em just in case I needed a spare or two. I traded one for the .010 (unused). He is a pylon racer and wanted one that looked like a q500 so two of them ended up V-tail. My v-tail has a TD .020 so I am hopeing it will outrun his...

I am thinking we are going to have to lose the gear though. It looks cool but makes it a bugger to hand launch and I am suspecting the performance is suffering a bit.

Now I have to break out the .049's and build a couple of pylon racers...

Steve

Tee Bee

Video

Here ya go, MJD. Not sure if you've seen it but I've posted it before. This was taken last summer during a nice calm afternoon.

http://www.youtube.com/watch?v=cf_ZF...e=channel_page

Steve Westphal

I was told that 35% heli fuel will work. Does that stand true with the .010 and .020? Does it need a splash of castor also? Thanks

skaliwag

My Feedback: (1)

My benchmark for oil in .010 fuel is 23%, the more of it castor the better.. I settled for 33% Nitro as the happy medium for plug life. How much oil do Heli's like in their go juice?

Steve Westphal

I see heli fuels as high as 60% nitro. All I have not found one yet with castor only. The ones I have found are 1/2 castor and 1/2 synthetic. Do I have to start mixing my opwn? I would rather buy it ready to go.

skaliwag

My Feedback: (1)

SIG Champion 35% Nitro with added Castor .. My fuel de jour for the TD .010 & .020's.
The Oil is Castor / Syno mix so add extra Castor.

Edit for Typo and clarity.

combatpigg

My Feedback: (3)

Straight castor doesn't blend if you go above 50% nitro..it floats around in clumps.
Even with Klotz synthetic as the base oil I've experienced problems introducing castor to high nitro [greater than 50%] fuel.
Unless someone has an anticoagulant ingredient to allow straight castor with 50% nitro, I don't you'll ever see it sold that way.

Max_Power

You sure you aren't thinking of boat fuel Steve? Boats often run that high of nitro but helis usually run either 15% or 30%.... usually easier to needle with 30 and a broader needle as you can't really tune a heli like a plane, you have to go out and do a full-power climb and then see how it falls back to idle as you auto rotate down and listen to it. You basically keep leaning it until it starts to "hang" at high rpm and make that "wha-wha-wha" sound when you chop the throttle or fall on its face in the climb. The problem in using heli fuel in 1/2a is most brands of fuel are 20-23% synthetic only (helis are ringed engines and these guys don't like the brown spots on the shiny muffler or the goo everywhere from inverted hovering). So it makes it hard to add castor without ending up at a insane oil level.

Steve Westphal

Max.....I found sources for nitro, methanol, and castor so I guess I will mix my own 35% nitro myself. I can buy both nitro and castor in quarts and methanol in any amount I want so I won't have 10 years of mixture going sour. Thanks.

ps......does anyone think that 35% nitro is too much for .049, .020,.010's?