Propeller For Babe Bee And Surestart

If you are just learning fly over grass and use the soft plastic Cox 5x3, 5x4, 6x3, or 6x4 "rubber ducky" propellers. They NEVER give as much power as the rigid, glass filled Master Airscrew, APC or Cox competition propellers due to excessive flex. However after a bad landing, or even a crash that buries the motor, the prop may still be good to go!

I find that the propellers flatten in use, so a 4 pitch will give similar performance in the air to a glass filled 3 pitch. Due to the weighted tips on the 5 inch safety tip propellers the 6 inch turn not that much slower, so the 6 seems to give better total performance. I usually run the 6x4 as a consequence in the "rubber ducky" prop. I recommend buying a half a dozen of each and trying them all.

If you are no longer crashing repeatedly, then flying over a harder surface and using rigid glass filled props, the 5x3 will likely perform better, but this is still not a guarantee as performance needs vary.

Phil

I agree with Phil.. (was writing as he was) I would get the "black" props close-to those sizes you stated. They're more flexible and safer for beginners. The "grey" props are competition props.. and are more brittle, but they are truer to their stated pitch because they don't flex as much. They will however shatter with even a light ground-strike. Any of their 5" or 6" dia. Cox props will perform decently no matter what the blade pitch is.. but Cox's PT19 Flight-Trainer came with a 6" x 2" L/H prop. I would recommend getting a couple of those. Do you have any L/H starter-springs? The L/H prop works with the Bee's "either-direction" running capability.. and a L/H prop will roll the airplane out.. rather than into the circle. This affords less engine offset, less tip-weight and more positive line tension. Everything you'd want for a beginner-pilot to learn on.

I'm sorry, a quick look at Cox Intl. revealed no 6 x 2 L/H props.. I would have thought they'd stock them; where the PT19 was the most popular airplane that Cox sold. There is the L/H 5 x3.5 if you like the idea of running the engine reverse rotation.

Thank you for the help and replies. I will probably just order a couple of props and try them out then. It is looking like a couple of 5 x 3's and 6 x 3's. Also running a left hand prop may not make a huge difference for me as I do have a little bit of offset built in.
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NEW222 wrote:Thank you for the help and replies.  I will probably just order a couple of props and try them out then.  It is looking like a couple of 5 x 3's and 6 x 3's.  Also running a left hand prop may not make a huge difference for me as I do have a little bit of offset built in.
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I guess you do!! I knew I'd seen that airplane somewhere. How long are the lines planned?

Your MA props will work well on all those. 4 pitch may be a bit much, the 6x3 can be trimmed to make an excellent prop. They are my second choice after the APC.

Nothing wrong with the Cox props either.

NEW222, a lot will depend on the desired lap speed for CL, weight and aerodynamics of the plane. I've always liked the softer nylon props as they took abuse over grass a lot easier than the stiffer reinforced plastic or wood props.

At sea level, there doesn't seem to be much difference between a 5x4 and 6x3 prop. At 6,500 feet elevation, I found that there was a marked difference, the 6x3 prop performed better on the Black Widow for my Airtronics Q-Tee. The 5x4 barely lumbered along. Air there was around 11.5 psia (0.78 atm) versus sea level at 14.7 psia (1 atm).

Not all props are equal, even though they may state same pitch and same diameter.

I'd try several different props, find the one that works best for your aircraft given your fuel, engine setup and atmospheric conditions, then stick with it.

roddie wrote:I guess you do!! I knew I'd seen that airplane somewhere. How long are the lines planned?

I was thinking of trying 42 foot and if that is too much, trimming back to 35's. I will be flying this only by myself, or letting friends fly it. Kind of as a trainer, fun thing. It will also mostly be flown at the cottage on the weekends.

As for the rest of the props, I had been playing around in my dungeon and had found a couple of props from about 15 years ago when I last flew control line. Found was an older Thimble Drome 5-3, a couple of the 5.5-4.5 (1 mounted, 1 not), and a Master Airscrew 6-3 new, and one on my Black Widow that I had actually forgotten about. The Black Widow is actually mounted to a Skyray profile, painted black and sitting right in my window, so I do not know how I missed it?

On another note, I will most definitely be ordering a couple of new ones in yellow, just because I can, I will, they look neat, and most importantly, for safety. Yes, I cannot trust myself at all times.

And I almost forgot to thank you all again for all of your help and advice.

Better take a set of both lines. 42' may be to long for a reedy if if there is any wind. With that sort of plane, make sure your launcher knows to point it slightly up and out and keep the lines tight. And don't toss it, just tell him/her to let go when you give the signal.
Rusty

Given the age of the COX props, you might want to boil them 10 or 15 minutes.  After boiling, bend the blades 20 to 30 degrees in both directions, then check for stress fractures running chordwise on the blades. If any fractures appear, toss the props.

roddie wrote:I'm sorry, a quick look at Cox Intl. revealed no 6 x 2 L/H props..  I would have thought they'd stock them; where the PT19 was the most popular airplane that Cox sold. There is the L/H 5 x3.5 if you like the idea of running the engine reverse rotation.

We have a crate of them but they "crackle" when bent as they have dried up to some extent. We have no problem throwing in some freebies with an order with the provision that it is understood that they must be boiled in hot water before initial usage.

Cox International wrote:... it is understood that they must be boiled in hot water before initial usage.

Just as an aside, is it OK if I boil mine in cold water?

dinsdale wrote:

Cox International wrote:... it is understood that they must be boiled in hot water before initial usage.

Just as an aside, is it OK if I boil mine in cold water?

Um
https://www.youtube.com/watch?v=DZ2tPVSoiH0

Just a thought.. If your Babe Bee is stock, you might want to try 30' lines initially.



I haven't tried running this.. but you can vent the Babe's tank for stunt/inverted flight using a "loop" of small size fuel tubing running around the "bottom" of the tank, connecting the two nipples. A simple V-notch can be cut in the middle of the length of tubing, to allow venting and prevent the fuel from syphoning-out while inverted. Alternately; two equal-length lines with a small "Tee" fitting or coupler-tube with a notch filed on-center would also work.. as long as the "line" can breathe.

dinsdale wrote:

Cox International wrote:... it is understood that they must be boiled in hot water before initial usage.

Just as an aside, is it OK if I boil mine in cold water?

Ha ... ha ... ha ...  must have been a good outing with the 'roo.

Just don't throw them on the barbie with the snags.

However, you could add them to the tub when you do the Aussie BB Game  

Cox International wrote:

dinsdale wrote:

Cox International wrote:... it is understood that they must be boiled in hot water before initial usage.

Just as an aside, is it OK if I boil mine in cold water?

Ha ... ha ... ha ...  must have been a good outing with the 'roo.

Just don't throw them on the barbie with the snags.

However, you could add them to the tub when you do the Aussie BB Game  

also cures toenail fungus.. but can be an extreme PIA