Experiment with the spring in the Babe Bee pickup tube

**RknRusty** Sat Oct 22, 2011 7:57 pm

I cross posted this over at RCG since so many people thought I was nuts to think the spring has any purpose besides preventing kinks. I argued the idea that it assists in feeding fuel. So I did an experiment and videoed it.
It'll play in HD and/or fullscreen if you wish. Here it is:

My channel: https://www.youtube.com/user/rastus10?feature=mhee

Kim Sat Oct 22, 2011 8:23 pm

Hey Rusty!

It'll take all night for the video to load on my dial-up service. What's the gist of the fuel line spring vrs fuel flow?

andrew Sat Oct 22, 2011 8:38 pm

He convinced me -- the spring really seemed to help pull the fuel up the line. It may be able to overcome a bubble in the line and ease initial starting.

Kim Sat Oct 22, 2011 8:45 pm

OK ...capillary action kinda stuff?

**RknRusty** Sat Oct 22, 2011 9:10 pm

Kim wrote:OK ...capillary action kinda stuff?

Yes, exactly, it is capillary action. I actually said as much in the video. Even if a bubble forms, the spring is still carrying fuel through the air cavity. I put springs in my Stuntman 23 tube and it starts much easier. It also no longer wavers in speed when the fuel gets low and I invert the plane, as in a loop or inversion. It used to slow a bit right after any of those maneuvers. Now it doesn't. I haven't actually field tested it yet, but I think it's promising.
It was a hit over at RCG too. I'm not a nut anymore. Laughing

Kim Sat Oct 22, 2011 9:29 pm

Well, I wouldn't have called you nuts. I've seen too many unusual deals like this turn out to be true! Good call...complete with follow-up experiment!

Now, I got to do inventory and make sure all my tanked engines have these ! You're making work for me, Rusty !

**RknRusty** Sat Oct 22, 2011 9:34 pm

Are you going to be able to watch it, Kim? Maybe it will be better if you go to youtube. Click the youtube button under my avatar.

EDIT: Or just try it. Put a spring in a fuel line and dip it in a cap full of fuel.

hlsat Sun Oct 23, 2011 4:50 am

Do something do not know.
I thought that the spring was to keep the fuel line to form.

nitroairplane Sun Oct 23, 2011 4:51 am

RknRusty wrote:Are you going to be able to watch it, Kim? Maybe it will be better if you go to youtube. Click the youtube button under my avatar.

EDIT: Or just try it. Put a spring in a fuel line and dip it in a cap full of fuel.

Lovely I too thought it was there to hold shape.
But I learned something from you Rusty, thanks.

**RknRusty** Sun Oct 23, 2011 8:54 am

hlsat wrote:Do something do not know.
I thought that the spring was to keep the fuel line to form.

That's what they say, but I bet whoever originally designed it knew it would draw fuel. Any engineer knows capillary action, I just can't believe nobody at Cox ever knew. The knowledge just got lost along the way.
Do we have any other engineers here? I'm electrical, but when we studied conductivity in metals we learned about it.

Mark Boesen Sun Oct 23, 2011 9:25 am

[quote="Kim"]Well, I wouldn't have called you nuts. I've seen too many unusual deals like this turn out to be true! Good call...complete with follow-up experiment!

Ditto! Congrats, nice work. The speed in which the fuel is drawn up is about as quick as if it was venturi pressure only, so I'd think its gotta help. Remember, the first year or two, Baby Bees and RR-1 had a black rubber tube with no spring, so if you find a early engine and its got a black tuel tube it probably came that way.

SuperDave Sun Oct 23, 2011 10:10 am

Additionally, the "pick-up tube spring" serves as a quasi-filter by catching any "crud" before it enters the needle seat.

gcb Sun Oct 23, 2011 10:34 am

Now the question is whether the fine folks at Cox knew this would happen. Perhaps the spring was for kinks and the capillary action was by accident...or not even noticed. OTOH, I don't remember having trouble with the black (neoprene?) tubing kinking.

George

SuperDave Sun Oct 23, 2011 11:12 am

As the revered visionary a LeRoy Cox was, let's give him credit for knowing. Smile

IME, neoprene doesn't stand up to nitro as well as the clear tubing so commonly used today.

SuperDave Sun Oct 23, 2011 2:23 pm

As further confirmation the capillary action in drawing fluids, when the tech pricks my finger to draw blood for testing she picks it up with a pipette having a figure over one end.

Quick and efficient.

nitroairplane Sun Oct 23, 2011 2:33 pm

Maybe you have re-stumbled upon an alternative to bladder or pressure tanks. Huh...

SuperDave Sun Oct 23, 2011 3:10 pm

nitroairplane wrote:Maybe you have re-stumbled upon an alternative to bladder or pressure tanks.

nitro: For bladder and pressure control problems I recommend a Foley catheter. If you don't know what this is in time you will. MUHHHHHAAAAAA.......................

:lol (OOOPPPS, wrong forum)

nitroairplane Mon Oct 24, 2011 8:49 am

It's alright Dave I'm not at the stage I need one of those at:)

gcb Mon Oct 24, 2011 9:29 am

SuperDave wrote:...IME, neoprene doesn't stand up to nitro as well as the clear tubing so commonly used today.

True, but back when the Babe Bee came on the scene, the fuel tubings I remember are the black neoprene, the green/ribbed plastic stuff, and the various sizes of Perfect brand plastic tubing. Those were all that were available at my LHS. Most became hard after a short time and had to be replaced often.

Oh, and a few guys who worked at a hospital could get scrap surgical tubing.

George

Edit: Type oh...

SuperDave Mon Oct 24, 2011 9:44 am

nitroairplane wrote:It's alright Dave I'm not at the stage I need one of those at:)

Nitro:

I read you age at 48 and surely your older friends have encountered bladder and pressure control problems.......................... They happen to all men if they live long enough. (Don't ask how I know this)

Oh well I'm just feeling humorous this morning. This too shall pass. lol!

hlsat Mon Oct 24, 2011 10:52 am

gcb wrote:
SuperDave wrote:...IME, neoprene doesn't stand up to nitro as well as the clear tubing so commonly used today.

True, but back when the Babe Bee came on the scene, the fuel tubings I remember are the black neoprene, the green/ribbed plastic stuff, and the various sizes of Perfect brand plastic tubing. Those were all that were available at my LHS. Most became hard after a short time and had to be replaced often.

Oh, and a few guys who worked at a hospital could get scrap surgical tubing.

George

Edit: Type oh...

George yes. I have many such tubes.

microflitedude Mon Oct 24, 2011 1:10 pm

All my tanked engines have springs, never knew they assisted in fuel draw - thanks for making the video.

Would feeding a spring into larger fuel system be helpful? Huh...

**RknRusty** Mon Oct 24, 2011 3:31 pm

microflitedude wrote:Would feeding a spring into larger fuel system be helpful?

It hits a pretty quick limit because it happens on a molecular level. ever read a rain gauge? Notice the water is higher around the edge than the center? That's capillary action and it only happens near the interface between the water molecules and those of the container. I don't know the equations, but it probably doesn't do much when it gets significantly wider.

nitroairplane Wed Oct 26, 2011 6:57 am

RknRusty wrote:
microflitedude wrote:Would feeding a spring into larger fuel system be helpful?
It hits a pretty quick limit because it happens on a molecular level. ever read a rain gauge? Notice the water is higher around the edge than the center? That's capillary action and it only happens near the interface between the water molecules and those of the container. I don't know the equations, but it probably doesn't do much when it gets significantly wider.

I'm sure it would make a bit of a difference especially if you got a thicker spring.

**Cribbs74** Tue Nov 01, 2011 10:49 pm

Not tooting my horn here, but since most of my pickup hoses are dry and hard and always retain their shape. I assumed the spring was there to allow a wicking action to take place. I guess being somewhat ignorant about cox engine operation payed off.

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Experiment with the spring in the Babe Bee pickup tube

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