High performance Integral tanks for Cox engines

Paulgibeault Wed Nov 05, 2014 11:45 pm

Hi Guys.
Those of you following my Vintage speed exploits are aware of my tank modification to uniflow venting.
Here is a photo of a photo where I first saw it some 20 yrs. ago. What your seeing is Master Modeller & top notch racer John McCollum's tank arrangement. John was kind enough to teach me many things about racing & even went so far as to build his entire AMA Class I Mouse race engine from scratch, as a research project. I don't know if John ever held the Open record but I do know he was near impossible to beat in a head to head race. Some of my wins over John were often because his pit man was not as fast in the pits starting & restarting as I was. So John's superior speed was occasionally lost in slower pit stops & pitting accidents in some cases...

1. Here's John's 8cc Silver Bee tank modified with a uniflow vent & very cool spring loaded overflow valve on top
High performance Integral tanks for Cox engines P1070218

High performance Integral tanks for Cox engines P1070218

Photos 2 and 3 show that very nifty home made spring loaded overflow valve in both open & closed positions. Note: John used a filter cloth over his 1/8" I.D. uniflow pipe as an air filter. John used a 1/8" vent pipe for quick filling. *That man thought of darn near everything!
2. High performance Integral tanks for Cox engines P1070221

High performance Integral tanks for Cox engines P1070221

3.

High performance Integral tanks for Cox engines P1070220

4. One other rather sneaky mod that John did was to seal up his backplate so that only a hole around the venturi was exposed. Then John drilled a 1/4" hole in the center of his aluminum motor mount plate. That 1/4" hole was then drilled straight through the top outboard nacelle block on the model. I never knew why until ~ 2 yrs ago! The normal engine sucks air through the bottom of the tank backplate. This area is close to the dirty ground & is prone to sucking in dirt & debris. John's model allows his engine to breathe clean air from up on top!!

Cheers, Paul

Theo Kleynhans Thu Nov 06, 2014 1:23 am

Thanks Paul

This is valuable information. Thanks for sharing this with us.

It seems that John was a real expert at this. The overflow system is quite cool.

Theo

Kim Thu Nov 06, 2014 5:54 am

Dude! What Theo Said!!!

Can't lose track of this stuff, so now, I got a "Paul Gibeault Engine File" in my Model Airplane Folder! You definitely got some cool friends also!!!

Thanks for all this great stuff !!!!!!!!!!!!!!

roddie Thu Nov 06, 2014 11:44 am

This might be a dumb question.. but from what you and others have experienced with the conversion of the small tank to uniflow, it would seem to be a worthwhile mod to make for flying c/l stunt.. wouldn't it? Not that the Babe Bee tank will give you a whole lot of time.. but it would be lengthened, due to eliminating the syphon effect. It would also allow extended inverted flight.. without loosing fuel out the vents.

I just re-read (skimmed) the Speed Secrets thread.. for how you blocked the vent on the backplate. I see that one is capped-off.. Is the other one filled with JB? Since the opposite vent has a tube extension for filling/capping-off, I would guess that you haven't had issues with it falling off. Your needle valve seal probably helps here. Would connecting the vents with a piece of fuel tubing work? I realize that this would be added drag on a speed model.. but it could actually add capacity to the tank. It would also be a visual fill indicator. If you fuel through one of the backplate vents while blocking the uniflow with a finger.. the tank will be full when fuel squirts out the open bridge-line. Connect it and fly.. no tiny plug to lose either.

These speed secrets threads have been extremely interesting Paul. Thanks for sharing!

Paulgibeault Thu Nov 06, 2014 12:42 pm

Hi Roger,
I would think you are absolutely right. A uniflow tank mod would make any Cox Integral engine run steadier in all phases of stunt , plus give a longer tank run.
MY way of making the tank uniflow is only one way. I suspect there may be other methods that work also. It definately gives a longer tank run in any event due to no more fuel siphoning.
If you look closely at some of the photos, you will see that I J-B Welded one of the backplate vents closed. My neophrene tube vent did fall off once & I got an off tune engine run. I've since found using a new (stiff) piece of neophrene before every contest seems to be sufficient for the time being...(lazy mans fix). I have seen a piece of tubing used to bridge the vent holes. It can work too. What I'd REALLY like to see is a miniature vent valve to do away with any tubing on top...
Cheers, Paul

roddie wrote:This might be a dumb question.. but from what you and others have experienced with the conversion of the small tank to uniflow, it would seem to be a worthwhile mod to make for flying c/l stunt.. wouldn't it? Not that the Babe Bee tank will give you a whole lot of time.. but it would be lengthened, due to eliminating the syphon effect. It would also allow extended inverted flight.. without loosing fuel out the vents.

I just re-read (skimmed) the Speed Secrets thread.. for how you blocked the vent on the backplate. I see that one is capped-off.. Is the other one filled with JB? Since the opposite vent has a tube extension for filling/capping-off, I would guess that you haven't had issues with it falling off. Your needle valve seal probably helps here. Would connecting the vents with a piece of fuel tubing work? I realize that this would be added drag on a speed model.. but it could actually add capacity to the tank. It would also be a visual fill indicator. If you fuel through one of the backplate vents while blocking the uniflow with a finger.. the tank will be full when fuel squirts out the open bridge-line. Connect it and fly.. no tiny plug to lose either.

These speed secrets threads have been extremely interesting Paul. Thanks for sharing!

roddie Thu Nov 06, 2014 11:08 pm

Paulgibeault wrote:

If you look closely at some of the photos, you will see that I J-B Welded one of the backplate vents closed. My neophrene tube vent did fall off once & I got an off tune engine run. I've since found using a new (stiff) piece of neophrene before every contest seems to be sufficient for the time being...(lazy mans fix). I have seen a piece of tubing used to bridge the vent holes. It can work too. What I'd REALLY like to see is a miniature vent valve to do away with any tubing on top...
Cheers, Paul

I thought a little about a valve.. and came up with this. It's super simple.. and should work.

inner-tube rubber used for a seal.. and pierced in the center with an awl.

High performance Integral tanks for Cox engines Dsc02116

High performance Integral tanks for Cox engines Dsc02116

#2-56 x 3/8"L machine-screw, nut and compression-spring.

High performance Integral tanks for Cox engines Dsc02117

#44 drill-hole (.086") in the top of the tank.. with screw/seal installed from the inside-out using tweezers or needle-nose pliers. Install compression-spring and nut on the outside, for adjustment.

High performance Integral tanks for Cox engines Dsc02118

High performance Integral tanks for Cox engines Dsc02118

shown open..

High performance Integral tanks for Cox engines Dsc02119

and closed..

High performance Integral tanks for Cox engines Dsc02120

Sponsored content

High performance Integral tanks for Cox engines

High performance Integral tanks for Cox engines

Re: High performance Integral tanks for Cox engines

Re: High performance Integral tanks for Cox engines

Re: High performance Integral tanks for Cox engines

Re: High performance Integral tanks for Cox engines

Re: High performance Integral tanks for Cox engines

Re: High performance Integral tanks for Cox engines