9 Cylinder Radial Build using Cox Sure Start 049's - Page 2 - RC Groups
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Jan 05, 2011, 02:31 PM
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jsesere's Avatar
Kool build.
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Jan 05, 2011, 04:37 PM
T.L.A.R. eng
Try here http://sdp-si.com/ for the gears. They have a large selection of metric and standard gears of several different pitches.

If you could find a way to incorporate a difuser fan of the rear of the crank shaft into the intake cavity, you could help the air/fuel situation alot. Just my opinion of course, definately want to see the engine finished.
Jan 06, 2011, 04:18 AM
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iamplanecrazy2's Avatar
Originally Posted by jsesere
Kool build.
Thanks Joe!

Thanks for the link T.L.A.R.! I'll see if they have what I need.
I mention something along the lines of your fan idea in one of the photo
captions in post #8. I was thinking more along the lines of an impellor
for some forced induction. The manifold pressure would have to be
such that it would not "float" the reeds. I have a prop from a K&B Allyn
Sea Fury out board that fits the Bee tank pretty well. It wouldn't take
much to lengthen the prop shaft so it would protrude into the tank.

Still no progress to report. Got to get some shop time in!
I hate it when life gets in the way of playing with my toys! <-- needs tears LOL
Mar 22, 2011, 10:03 AM
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How's this project coming along? It sounded really cool. Just wondering?
Sep 23, 2011, 04:51 AM
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iamplanecrazy2's Avatar

Finally back to work on this project!

I can't believe it has been 9 months since I worked on this. Time sure flies!

Made good progress the past couple of days. Just about finished all of the
reed housings, ground the bottom lugs off all of the cases, and sized screws to attach cases to back plate. Here are more photos:

Cutting the Sure Start back plates down on the band saw left an uneven ridge on the reed housings which had to be smoothed off for a
good fit to the back plate. Used a late model case as a fixture for turning them with the drill press against a piece of aluminum covered with 280 grit sand paper.

Snugged up screws in the case:

Cut the heads off:

Ground them down on the bench vise so they would not protrude past the reed housing:

Here it is chucked up in the drill press:

The ridge really came off nicely. I would turn the housing a bit on the press
then take it out and check it. Took several passes but working slowly paid
off with a nice smooth even surface.

I ground the lugs off of the cases freehand against the disk on my bench
sander. It worked very well and holding them sure let me know when they
needed cooling down.
The reed housings needed to be ground to match the cases. They were
shaped freehand same as the cases.
Here are the cases and reed housings mounted to the back plate.
It is starting to look like a 9 cylinder radial now!

Its time to finish up the changes to the choke tubes! Thats next.

All that is left to do to the reed housings is final sizing of the inlet tube.
The grove in the one on the left is where the hole was for the Sure Start
spray bar. I'll take it down until the grove is gone. The one or the right is
almost there. An O-ring will seal the joint with the modified choke tube.
Should have more to post in a few days.
Last edited by iamplanecrazy2; Sep 24, 2011 at 04:33 AM.
Sep 23, 2011, 08:43 AM
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Reginald's Avatar

Cox radials

Very nice work indeed. Maeby this one can inspire you to go on. This is the very very rare Japanese Hobby Air Products of 1968.
Sep 23, 2011, 10:11 AM
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jsesere's Avatar
Let me know if you need to borrow my Illudium Q-36 Space Modulator for the finishing touches lol.
Sep 23, 2011, 03:11 PM
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Great ! so far :-) Just from looking I'm wondering IF only 2! screws will be man enough to hold the cases/plastic backplates tight enough against air leaks?? Wouldn't think so IMO.
Perhaps an ali disc on the front to clamp all those motors down tightly?

My mind just boggles at the thought of getting that many COX's firing at.. one go.. on the same day.. Imagine what a replacement set of plugs would cost.
Sep 23, 2011, 04:47 PM
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iamplanecrazy2's Avatar
Thanks Reginald. The Hobby Air engine photos are great.

Thanks for the offer Joe, I just might need it to get this thing done! lol

You are right Bare, the 2 screws won't do. I will be adding 9 more that
will secure the front bearing mounting plate and pull the cases down tight.
Will do that part as soon as I get the choke tube mods finished.
Sep 23, 2011, 06:27 PM
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earlwb's Avatar
it is looking good so far. Please keep up the work. I like it.
What you really hate is when you get it all bolted up and you have a bunch of extra screws left over, and now you have to wonder if you missed one someplace.
Sep 25, 2011, 10:05 AM
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iamplanecrazy2's Avatar
Thanks Earl. Work on the choke tube mods is progressing nicely.
I hope to have them finished sometime today. Will be posting more photos.

This may be a bit premature but I have been trying to come up with a name for the engine.
Total displacement is .441 c.i. so I thought 44 Magnum sounded good.
Or how about Mega Bee?
Anyone have a suggestion? (Besides paperweight! lol)
Sep 25, 2011, 10:49 AM
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earlwb's Avatar
.44 Magnum Nine?

Mega Bee is pretty good though.
Sep 25, 2011, 08:19 PM
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iamplanecrazy2's Avatar
I think I'm leaning more towards Mega Bee. It just seems to fit well.

I came up with a way to turn the choke tubes that is providing great results.
To chuck them I ground a slight taper on a section of a spare allen wrench
and slid the tube onto it. (The inside of the choke tube is tapered.)
This gives the tube much needed support when chucking it up and when turning
it. For a cutting tool I ground a cutting edge on the end of a spare drill bit
and clamped it in the the drill press vice. It really works well.
Once I get this done to all nine tubes I'll be cutting them to length. Planning
on using the drill press for that also. Will use a makeshift drum sander to
get them down to the finished length. This will give a concave end that will
match the inside of the 8cc tank.
Here are some photos.

This is how far I got with the tubes using the hand drill. It was too slow and
a bit dangerous so decided to go with the drill press to finish them up.

This is the tapered piece of allen wrench.

Here it is inserted into the tube. This keeps the drill chuck from just crushing
the tube as the tube itself is inserted into the chuck. It also adds stability to
the tube as it is being cut.

Here is the drill press set up and ready to turn a tube. The drill bit made for
a good cutter!

This is the side of the tool that the tube is turning into. I move the cutter into
the tube with the screw adjustment on the drill press vice. I was amazed at
how well it worked out. I almost feel like a machinist! lol

A close up from my point of view when cutting.

The end result is quite smooth and size is spot on. I would check diameter
with a dial caliper several times until cut down to final size of .328"

8 more to go! Will post more soon!
Last edited by iamplanecrazy2; Sep 25, 2011 at 08:25 PM.
Sep 25, 2011, 09:24 PM
Registered User
Wow that's just unbelievable, way to go man !!
Sep 26, 2011, 01:51 AM
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iamplanecrazy2's Avatar
Thank you Fawaz!

All of the tubes are on! They still need the final sizing of the tube length
but I wanted to see them mounted first. The inner 9 holes still need to be
drilled in the mounting plate. These will get screws long enough to pass
through and secure the front bearing plate. This will also pull down the
cases tight making up for the missing screw lugs.

I'm pretty sure the venturi shown has too large of a bore. I have another
I plan to use but it will need to be cut down to fit the opening in the 8cc tank.

Time to get to work on the front bearing plate.

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