Hi John,

Fun it should be!! I am attaching the PDF file for Pat King's version of a Beginner's Ringmaster. He shows a Sure Start version as well as a tank mount version. That should give you an idea of how to handle the nose modification. 

John
The baby plans are here and they show a balance point, http://www.hippocketaeronautics.com/hpa_plans/index.php
If you are not a member you have to join, but it is free.

JV

Here is a screen shot of Pat King's Baby RM nose area.

With a Baby Bee with an integral tank, it'd probably balance fine.  With a Cox product engine, you don't have the weight of the integral tank, or the additional length.  To make it balance and fly close to the design, you need to stretch the nose about an inch.  One of mine started with the stock nylon mount and a product engine, it was tail heavy and hard to fly.  The nose has since been stretched and reinforced and it flies better now.  

Well she is ready for first flight.  Right now it is windy so it may be a day or two before first flight.  CG came out about right.


       

Very nice John!!  What did you use for the container for the balloon??

Very nice John!!  What did you use for the container for the balloon??

A cut down syringe.

Hi John,

I really like the Baby! 

If I may suggest something to "play" with once you have it flying good is to replace the prop with a reverse rotation prop.  They are readily available and it will be a good experiment as to what differences the different props make to flying characteristics.  I would like to hear your comments.

BIG Bear
RNMM/AMM

Cool!  I have a reverse pitch prop in hand.  Will give it a try.

John, a lot of variables like wind that day, nitro, how that sure start is running, etc. but the 40' should be a good starting point. I keep a set of 32, 35, 42 and 48 foot lines to try. Those are all Spiderwire, i have a set of .012 42' and 45' for contests using more powerful engines.

Do you have a fine needle valve you are using with this balloon?  Or just standard?  I've been thinking of using a bladder on the one I'm repairing for the flyathon, but don't have the fine needle.

You do understand that a balloon and a bladder tank are two different setups.  Bladder has pressure, balloon does not.  It is a stock product engine with he standard Cox needle.  The balloon tank seem to work fine with the Cox needle.

No, didn't know that. I thought the balloons were the old bladders.  So, what's the benefit to a balloon over a bladder or tank?

Hey Duke:

Balloon tanks use a party balloon with a small enough fuel load that the walls are not stretched.  The balloon never adds pressure to the fuel, it just holds the fuel in a way that gives you no bubbles.  They pretty much act like tanks, except for the "no bubbles" part.  They work great.  Ask, and I shall post a picture.

Tanks are tanks.  On 1/2-A planes, bubbles can be a real pain in the neck.

Bladders (which I've never used) are run stretched, and pressurize the fuel.  They're great if you've got a big wide-open venturi that can't draw by itself and that you're trying to feed, but they come with their own problems.

By the way a very popular canister for the balloon is a 35 MM film can.   Getting hard to find.  No one uses film anymore.

I took some clear plastic and rolled it to get an about-right-sized tube.  I'd like to say "it works great", but I haven't flown it yet.

On another plane I made a radial motor mount (for a Wen-Mac) that's big and hollow and has a hole big enough to stuff a balloon tank into.

http://stunthanger.com/smf/index.php?topic=12603.0

I kinda knew what balloon tanks were, but thought they worked like the bladders.  But I was wondering what the benefit is. does it work better than a tank?

Yes, because tanks give you fuel and bubbles, and a balloon just gives you fuel.  Bubbles are a problem with bigger engines, but not nearly as much as with 1/2-A.

Well she is ready for first flight.  Right now it is windy so it may be a day or two before first flight.  CG came out about right.

John -- nice job, and sorry if I helped pull your thread off into the weeds.

Let us know how it flew -- I've never flown any 1/2-A control line with 3-D wings: I need to get something stuck together.

Very nice John!!  What did you use for the container for the balloon??

The cut down syringe was too small.  I have changed it out for a 35 MM film canister.  I now have a true 1/2 oz tank.

The cut down syringe was too small.  I have changed it out for a 35 MM film canister.  I now have a true 1/2 oz tank.

I have the first flight behind me.  It flew ok but was light on he lines.  I am working on this.  Engine offset, shorter lines etc. I also will try the pusher prop.  By the way I have now installed a glue stick tube to hold the tank.  It is smaller than he 35mm canister and bigger then then the syringe tub.