9 Cylinder Radial Build using Cox Sure Start 049's

[iamplanecrazy2]

I started building a 9 cylinder radial based on John V Thompson's "Trantula 9 Cylinder Radial". Here is a link to an article about it:
http://modelenginenews.org/cardfile/tarantula.html
His is truly a work of art. Doubt mine will be anything close to it but I'm having fun with it and that is all that matters to me. Don't know if it will run or not but it will at least be something nice to put in the display case. I can always tell everyone it turns an 18X4 prop 10,000 RPM :roll:
Cost wise I'm not out much. I got the Sure Starts when they were on sale on the Cox Hobbies web site for $6.99 each.

I wanted to post progress of the build here but I can't post photos on this forum because I lack a photo host. I started a thread on RC Groups and
am providing a link to it here. Hope that is ok and I look forward to any
comments or suggestions.

http://www.rcgroups.com/forums/showthread.php?t=1362796

[altidsulten]

Do you have the drawings for it?

Regards
Thomas Pedersen

[Frank Klenk]

planecrazy

Photos would be great. You can get a photo host free. Photo bucket offers their service for no charge. here is a link
http://photobucket.com/

Frank

[iamplanecrazy2]

I don't have any drawings Thomas. I've been figuring it out as I go along.
I probably should make some detailed drawings of what I'm doing. Will for sure if it actually runs.

Thanks for the Photo Bucket tip Frank. I'll look into that. My computer is a
Mac and often times such things are not compatible with it. If you see photos here you will know it worked out.

Tom

[iamplanecrazy2]

I did some research and decided to give flikr a try as it seems to be the most Mac friendly photo sharing site. I'll try and post a photo here as a test. If it works I'll be following up with text and more photos.

[iamplanecrazy2]

It worked! Thanks for the tip Frank!
I'll be posting more tomorrow.
Tom

[altidsulten]

Hi,
I am looking forward to see more!
Have you found the gears yet??

Regards
Thomas

[iamplanecrazy2]

I found the gears Thomas but it looks like I'm going to have to wait
6-8 weeks to get them! I'm still looking and am thinking now that I
should have bought gears before ever getting started.

I hope to get time to post more photos and text here soon.
Tom

[iamplanecrazy2]

Here are some more photos.


Drilling a Cox 8cc Bee type tank for use as a fuel manifold.


Manifold with venturi and one of the Sure Start 049 choke tubes that will be
used to tie manifold to the reed housing.


Cutting down the Sure Start back plates. Made a fixture to hold them and
modified a socket to rotate the back plate with. A stop on the fence controls
the cut depth.




The drill jig I made for drilling the plate the Sure Starts will mount on.
The plate is the back plate from a 3 1/2" aluminum spinner. I am planning
on using the spinner as a shroud to cover the gearing and cases as well as
for the actual spinner on the front of the prop shaft. If nothing else this
engine will be a nice display piece. Will it run?????


The manifold with all the modified choke tubes attached. Tubes still need to
be shortened.

I am currently working on finishing up work on the choke tubes, trimming
the reed housings, and modifying the crank cases. Hope to have more to
show in a few days. I'm also working on getting my 6" Atlas lathe up and
running as I will need it to make the prop shaft and prop shaft bearing
housings.

[Saltmine]

Wow! It's amazing to see what you've accomplished with limited tooling.
I'd like to see more photos , too. I have this crazy idea of making a three-cylinder, four-stroke radial from three HP-.21's.

[iamplanecrazy2]

Thanks for the post Saltmine, it got me motivated to get back to work on this project. I can't believe it has been 9 months since I worked on it.

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 sander 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! Outside diameter is 5 1/8".
Weight so far is 14.1 ounces.



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


All that is left to do the 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.

[iamplanecrazy2]

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!

[iamplanecrazy2]

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.