Performance RPM of RR-1 .049

I would say more fragile. I have seen broken crankshafts and broken drum valves in the RR-1 engines.

I would assume the weak point of the engine may be the small pin that connects the crank pin with the rotating valve. I have a RR-1 but I have never used it other than on a bench and especially not for so long as one of my TD051-s that has near 300 hours runtime on it and still starts and runs fine.

Yes it does look a bit complicated. The TeeDees likely miss stable.
Iceberg

Jason_WI wrote:I would say more fragile. I have seen broken crankshafts and broken drum valves in the RR-1 engines.

I am surprised that the drum valve would be a problem. How do they break?

I have an RR1 that is a little rough on the exterior but appears to be almost new inside.  One thing though, the drive hole in the drum valve seems to be a very sloppy fit to the drive pin.  Neither show any signs of wear, the hole is perfectly round as is the pin.  Is it missing a bushing or is it designed to have that much play?

I haven't run it yet for that reason.

The play is there to make it easier for everything to line up. It gives the system some radial play.
I measure about 0.092" hole in the valve and about 0.075" diameter drive pin.

I didn't measure it but around .020 play sounds about right. Guess I'll fire it up and see what happens. Thanks!

Interesting regarding the facts I knew little of, given the fragility of the RR-1 and its rarity, can see now that it is best a collector engine, reserved to be gently run on occasion, unless one can manufacture their own parts. That I gather is for all the half-A and A sized rear rotary valve Cox engines.

Given the durability and simplicity of the Tee Dee, Medallion and reed valves, I can see why they won out.

Rusty had one from Mudhen that hauled the mail on one of his wings, I can't find that thread anywhere.

Right now that engine is in my shop.

I also ran an RR1 on a Goldberg Wizard like 5 yrs ago. I never did tach it, but it moved along pretty good. There is a video of that flight in this forum somewhere.

The drum broke on mine, but I was lucky to receive a replacement.

Cribbs74 wrote:Right now that engine is in my shop.

I also ran an RR1 on a Goldberg Wizard like 5 yrs ago. I never did tach it, but it moved along pretty good. There is a video of that flight in this forum somewhere.

The drum broke on mine, but I was lucky to receive a replacement.

How did it break,
I mean did it gaul, crack, disintegrate...?

It broke at the web of the intake port. Just fell apart. The drum is a pretty thin piece, it wouldn’t take much to break it. I don’t feel that it’s a fragile engine though and would use it again without hesitation.

Interesting... Glad you found a replacement.

Here is the video. Can’t believe how small my kids were. My son still had his baby voice. This is when I first learned to fly CL, I’ve come a long way since then.

Looks like the motor runs well. But seems the teedee was cheaper to produce and maybe a bit tougher. Thanks for the pictures of the RR-1. Is there a manual from cox that actually shows the motor properly? The one I found was barely a starter guide. Not shop manual at all.
Thanks
Iceberg

Iceberg wrote:Looks like the motor runs well. But seems the teedee was cheaper to produce and maybe a bit tougher. Thanks for the pictures of the RR-1. Is there a manual from cox that actually shows the motor properly? The one I found was barely a starter guide. Not shop manual at all.

May be here, about half way down? Cox Engine Instructions

Hi yes i had seen that sheet about the RR-1 before. However doesn't have any specs about rpm or much else but normal standard starting suggestions. But thanks for the link. Love a shop manual sheet?
Iceberg

Sorry, unfortunately, I haven't been able to find much info on the RR-1, like a parts manual or a magazine article review. What I share below you probably already know. Thus far, I gather it must have been lackluster sales and its less profitable production costs that done it in when the Tee Dees and Medallions gained traction.

There is a little discussion of the RR-1 here in RC Groups:

RC Groups Reedy vs Tee Dee, page2, Post# 22810562 starting

The info is probably out there somewhere, but I have yet to see a shop manual on any of the Cox products (but then I'm a sport user and not a competitive flier). Best I've seen is a parts diagram and what is expressed in magazine articles. It appears that the RR-1 never received much attention, and vanished with the other Cox engines marching on. The key sources such as Mark Boesen's compendium he maintains and others only mention the engine in brief. If info was available, it would have been archived somewhere.

In spite of its 9 year production life, it remains among the rarest of Bees.

Wikipedia.org Cox model engine

Wikipedia, 1956 RR1 (Cat#390 - manufactured 1956-1965) wrote:The rare Cox RR1

The RR1 uses a rear rotary valve intake rather than a reed valve in an attempt to achieve more power. The engine came after the Babe Bee and looks very similar with its anodized, machined extruded aluminum crank case and fuel tank. The power improvement was negligible so Cox reverted to the cheaper easier to build Babe Bee. The engine was made for quite a few years and sold for $6.95. A left and right hand rotary valve was made, as were left hand 6x2 glass filled nylon props for the RR-1. Some versions have a blue tank, others have a clear anodized tank. There were two versions of the tank back as well, to fit the corresponding tank. It has become a collectors item due to its uniqueness and pretty colors and is worth around $300 in 2008.

Interesting that it would have used the odd 6x2 prop as the Bees seem to do best with a 6x3, which tells me that smaller diameter props and higher RPM's would be its forte.

mh-aerotools.de - The Cox Bees has info in brief about half way down.

Congrats on gaining ownership on a rare one and good luck on finding the info you are looking for.

I remember that video Ron (before you cut that tree down) lol I have a RR-1 and had it apart at one time but i don't remember it having slop at the con. rod pin .

Here's my RR1 on my 'Tube channel. Notice it has a Bee Crankcase, but other than the grooves and anodizing, it's the same. Mudhen gave it to me, and I passed it along a few years later to Ron Cribbs:

https://youtu.be/wXL2t4eKn-I



Note: for some reason the embedded video doesn't always work, but the direct link to YouTube does.

Cool and good to hear from you Rusty , Funny to see you flying back then (like me all over the place ) and what you have graduated to ! You and Ron like flying close to trees reminds me of RC when i was fling and got a few stuck in the trees LOL . Take care , Eric

Cribbs74 wrote:Here is the video. Can’t believe how small my kids were. My son still had his baby voice. This is when I first learned to fly CL, I’ve come a long way since then.

That is really good flying done by your son, Ron. RR-1 really makes that Li'l Wizard really move out. Regarding the baby voice, yup, they grow up quickly.

RknRusty wrote:Here's my RR1 on my 'Tube channel. Notice it has a Bee Crankcase, but other than the grooves and anodizing, it's the same. Mudhen gave it to me, and I passed it along a few years later to Ron Cribbs: [....]

Wow, RR-1 makes that Li'l Satan sing, Rusty. Would RR-1 power approach that of the Venom or perhaps exceed it a touch?