Cox 290-9 Windback Engine

Cribbs74 wrote:Is the starter a drive plate? If so then my guess is it presses onto the crank.

OTOH if that is a stud that goes through then you may have to lock the crank and unscrew it off

Just a guess!

Ok, the starter turns with the prop stud and crank, and
what looks like a drive plate behind the starter
stays fixed with the case.
Hard to describe Ron.
I'm leaning towards pressing the stud and crank, but
not tonight. More investigating first.
Bob

If you press that off be prepaired for the flat coil spring to shoot out like a snake in a can. The only thing holding it together is the fact its pressed on the crank.

Hi Bob,
Nice score, congrats!
As you probably know that's a fairly rare engine, its actually known as a 350-9 Babe Bee with "Cam Roller Starter Assembly" and made for only about a year ('71-'72) for the Rivets model. Apparently Cox got a cease and desist order from the lawyers of Testors and the company scrapped all remaining inventory of starters. Although they're rare, not many know much about them and since demand is low so is the value...but if your looking they're one of there harder to find!

Bob , never had one off but if your going to press it I would tape it up good with some masking tape to keep from coming apart like Jason said / the old snake in the peanut can man good memories there . Eric

I actually have a couple of these engines. I would not recommend taking it apart, and don't think it is necessary. A heat gun and solvent/lubricant should clean out the crankshaft. The spring attaches to the cam through a hole. I received one of these engines that was broken and actually had to reattach the spring. I haven't had any problems with it. This particular engine is one of my favorite cox variants. Nice score. Andy

anm2 wrote:I actually have a couple of these engines.  I would not recommend taking it apart, and don't think it is necessary.  A heat gun and solvent/lubricant should clean out the crankshaft.  The spring attaches to the cam through a hole.  I received one of these engines that was broken and actually had to reattach the spring.  I haven't had any problems with it.  This particular engine is one of my favorite cox variants.  Nice score.  Andy

Well, while you were posting Andy, I was breaking the engine down.
It went very well(no damage). With the prop plate exposed, it's
easy to see how it operates. Just a couple of dogs that slide back
and forth to free or lock the plate and crank.
By the looks of things, this engine was hardly, if ever, started.
Jason, I think the assembly you were thinking of was the Testors
one that has the length of spring steel coiled up inside.
Bob

The last picture shows the hole in the cam I was referencing. The Reed Valve in the picture looks almost unused. Very nice. It looks like the only thing you are missing is the Rivets Airplane:)

anm2 wrote:The last picture shows the hole in the cam I was referencing.  The Reed Valve in the picture looks almost unused. Very nice.  It looks like the only thing you are missing is the Rivets Airplane:)  

Thanks Andy. I think I'll call her "cease and desist", because
she also sports a "W" glow head.
Oh, and Ron Cribbs, you were right with your first instinct about disassembly.Thanks
Bob

Glad you were able to break it down Bob!

That roto-starter is one of the cleaner looking designs I have seen.

I've been staring at the photos.. and I can't figure out how it works. Must be very similar to the Testors design.. aside from the winding-spring. I have a Testors "Pipe Bomb" .049 with a similar looking starter.. but I never closely examined it. It works, but I've never had the front-end taken apart. It is steel correct? That makes for a heavy airplane engine. There's probably as much; if not more weight.. than the engine's top-end I'm thinking..

This engine/starter combination seems like it would be a good fit for a tether-car. Re-name it the "pull-back" starter. Pull your racer back a few inches while pressing down.. and lift to release the spring-force and start the engine.

roddie wrote:I've been staring at the photos.. and I can't figure out how it works. Must be very similar to the Testors design.. aside from the winding-spring. I have a Testors "Pipe Bomb" .049 with a similar looking starter.. but I never closely examined it. It works, but I've never had the front-end taken apart. It is steel correct? That makes for a heavy airplane engine. There's probably as much; if not more weight.. than the engine's top-end I'm thinking..

This engine/starter combination seems like it would be a good fit for a tether-car. Re-name it the "pull-back" starter. Pull your racer back a few inches while pressing down.. and lift to release the spring-force and start the engine.

Roddie, It is very similar to the cam starter. The end of the spring fits into a hole in the back of Prop Driver. When you engage the propellor by turning it clockwise it compresses the spring. When you release the propellor the spring swings the propellor counterclockwise. When the propellor is turning counter clockwise the back of the prop driver does not engage the spring and it turns freely. I am sure there is some friction which would slow the RPMs. Perhaps that is why I see these engines with High Compression heads. I think they came from the factory that way. Cox developed a concept car engine using the same type of mechanism (according to the Cox Model Engine Handbook) that never went into production because of Patent infringement. Andy

Weighed it at work today...............yikes.
Bob

Probably worked well with the model it was used on.

The first version of the Rivets had several problems and after they discontinued the "starter" version, they just used the traditional spring starter until several changes were made to improve flying, including this brass nose weight. The last version was only made for about a year and was replaced with the purple Super Sport, probably due in part to the extra cost of manufacturing this brass slug!

Mark Boesen wrote:The first version of the Rivets had several problems and after they discontinued the "starter" version, they just used the traditional spring starter until several changes were made to improve flying, including this brass nose weight. The last version was only made for about a year and was replaced with the purple Super Sport, probably due in part to the extra cost of manufacturing this brass slug!

This makes me wonder about the Testors/Cox "Cosmic Wind" story. Testors probably used their spring-starter in that model. My Cox Cosmic Wind has a weight (lead) in the nose.. (wanna' bet it weighs 10gr.?)



Cox wouldn't have designed the model this way I'm sure.. but it was the only way to balance it.. since moving the engine forward wasn't enough to compensate.  My version came with the product engine fitted with the later hex drive-plate for Cox's 2-piece plastic-cam style spring-starter. This style is great for a deeply cowled-in engine.. and is what I used on my Bearcat Speed model.




I had to make a drive-washer extension because the prop was too close to the cowl.

That's a nice looking profile plane, Roddie.

GallopingGhostler wrote:That's a nice looking profile plane, Roddie.

Thanks George. I can't speak for all contestants of CEF's 1st Reed Speed contest.. but I personally enjoyed having to design an airplane to meet the contest's criteria. No kits for these! I kind of lucked-out with the lines. They're eyeballed.. for the most part. I found Bearcat 3-views and studied them.. but didn't want to scale them exactly. You have to create an illusion with a profile.. and actually most of the thought was put into the fuse's shape.

It started out like this..




Although I later went with a Killer-Bee style back-plate, the Babe shows the cam-starter spring that I new I'd need to use with my planned cowling. I wanted to keep the distance between the spinner and cowling to a minimum.. and also have some separation between the cut-outs in the cowl for the crankshaft vs. the cylinder head.

Roddie,the 'ili'Bear is the sharpest plane I"ve seen,I"ve admired it for awhile,do you have any air time on it. Rat

rat9000 wrote:Roddie,the 'ili'Bear is the sharpest plane I"ve seen,I"ve admired it for awhile,do you have any air time on it. Rat

No.. it hasn't flown yet. I did "try" once. It was right on the deadline of the 1st speed contest.. and I was having multiple problems. The engine didn't want to run consistently.. and was a Bear to start. Add to that; nose-over after nose-over.. and I was beginning to think it was sign "not to fly it" before going through the engine again. I was also using a pin-release (stooge) that placed the tail-wheel 1/2" above the rough asphalt that I was flying from. It wouldn't move 2 feet without nosing-over. I'm confident that it will fly with a good engine run. Wingspan is 17.0" and it's area is 70.125" square inches. The root-chord is almost 6 inches with an average chord of 4.125". Weight dry is 7.20 ounces. Fuel tank capacity is 6.15cc's. The engine has a Tee Dee .049 cyl./piston, std. glow-head, stock case/crank, Killer Bee backplate and a Cox 5 x 4 black prop. The next attempt at a flight will be over grass.. and I will lay-out some lg. sheets of corrugated cardboard for a runway. I also have some APC 4.75 x 4 props that should really increase performance.. as long as I can get them bushed/balanced properly. I was too nervous to run them previously.

Thanks for the compliment!

Found this on the Bay today. It's a 350-9.
Has the windback starter and #1 p/c.
Missing the spring, but I should be able to
use a SureStart one with a little modification.
According to Tim Daniels, there were only 10,00
of them made, so I just had to have it.
Bob

Gooden !! I like the look nice Bob they are few between to find ,,, Strato Bug would do me right now ,, BUT $$$$ STANDS BETWEEN US  Eric  

dckrsn wrote:Found this on the Bay today. It's a 350-9.
Has the windback starter and #1 p/c.
Missing the spring, but I should be able to
use a SureStart one with a little modification.
According to Tim Daniels, there were only 10,00
of them made, so I just had to have it.
Bob

Surestart spring will work but its about 2 turns short on the spring. IIRC it needs to have 10 turns and the SS spring is 8. The end tip of the spring then needs to stick out further and can pop out easy if wound back too far. It works but not ideal. I have done this to mine that I bought without a spring.

Thanks Jason, good information.
I have the 190 at the top of this
thread. I'll have to pull it out and
have a look.

Hey Eric, thanks. Your Strato is out
there somewhere.

Bob