Mr Cox

I been thinking about the QB engine for a while, it looks so pretty yet seems so lame. One error is the straight cylinder but the regular plug is also a great power robber, and I wanted to see what would happen if it had a proper glow plug/head.

So with a new cylinder/piston set and an TD09 head for turbo plugs i gave it a go. On 20% castor and 10% Nitro it spinns a graupner 6x3 at around 17500 rpm (even sometimes peak at 17900). Hey, that's better than a stock TT 07 GP....

I had to document this, as I can hardly believe it myself; http://www.rcuvideos.com/video/Cox-Queen-Bee

I have no idea how long this will last, the piston/liner fit is poor, but if anyone else has a QB laying around it might be worth a try...

JCT049

Mr.
I have had a QB 074 for years and it runs great. I admit that it is not powerhouse but it will throttle well. The QB 074 runs fine on 10 percent nitro fuel. Maybe I am lucky that the one I have has good fits. A TD09 head should increase the RPMs some. I have seen where guys stated that their QB 074 is not a great engine from Cox Mfg. Mine is dependable and use it often.

JCT049

DICKEYBIRD

Cool stuff Mr. C!

More important to me than 6x3 rpm's is how fast it will turn a 7x3 and how well it idles and accelerates. I have an almost new Q.B. that I want (someday) to try one of my Medallion .09 heads and a 7x3 on for a light, old-timer style airplane with ailerons. I luv those slow, cross-controlled, steep approaches with the sticks in the corners.

Mr Cox

It gets really hot already on the 6x3 so I don't think it will like a 7x3 very much, it is not that kind of engine. Maybe on lower compression, Texaco style, but then the stock head might be a better choice.

For old-timers and large props there are always the diesels, that is one thing they do very well. I have a PAW 09 RC in a thunder tiger scooter and it is a much better match than the TT 07GP that it is meant for...

combatpigg

My Feedback: (3)

The reason why it gets hot with almost NO LOAD is LOW compression. There is not enough compression to fire an adequate charge of fuel, so the needle has to be set lean [on the verge of dying] just to support weak combustion. There is no magic amount of castor or no magic break in routine that can reverse this unfortunate situation.
I bought a QB based on a glowing review done by Chris Chianelli right after the engine came out. I could not get it to run. By this time I was already an experienced runner of .049 stuff. I sent the QB back to Cox twice, they sent it back twice saying that the engine was perfectly good.
From that day on, I never bought any engines directly from Cox, they lost my retail business.
The only thing that I can think of trying to restore compression is to expand the piston with a custom made tool in a press. The leadloy might be soft enough to grow a tiny bit without cracking.

DeviousDave

Too bad you are so far away, I have a junk Queen Bee that you could use for parts. It was low time, I just lost interest in it as it got dustier.

BobHH

My Feedback: (18)

CP, if you want to increase the compression use yours like I did mine! Makes a good fishing weight. After a while you get a bit of buildup in the cylinder and the compression increases. Unfortunately it scares the fish away!!![sm=spinnyeyes.gif]

Bob Harris

crossman

I have an old QB that I haven't tried to fire in quite some time. I don't recall the compression being that soft. It came on a small bipe that I picked up at a garage sale. The bipe isn't quite small enough for that engine. I have a Magnum 15 for the bipe now, I've been wondering if the Queen Bee might work on a DNU.

Any thoughts?

DeviousDave

It would fly a DNU, but not with authority. It isn't very powerful for its weight.. The only airplane I ever "committed aviation" with using a Queen Bee was an Aerocraft Snapper. Airplanes don't get a whole lot lighter than that, and it had a lot of wing area. When the speed was up, it would loop and roll, but any kind of headwind just about stopped it in it's tracks. Shame as the Queen Bee is a really nice running engine-it just lacks Testicular Fortitude.

It might be ok on a trainer or Rudder/elevator type plane. With radio gear being so much lighter than they were when the QB came out, you might be able to make the All Up Weight a wash in a plane like a Bee-Tween or the like.

combatpigg

My Feedback: (3)

Good one Bob! Let the barnacles build up in there.

How about sending the QB out to Frank Bowman so he can fit it with a tiny ring?

DeviousDave

Heating the piston up cherry red with a propane torch may swell it a little. I knew a guy that does that with is TD's to make them last longer, and he has to re-lap the piston when he's done.

jetpack

My Feedback: (1)

Bought mine second-hand, looked like just a few runs on it.

Stripped it down, cleaned it..checked the piston fit...fell right through.

Spent the rest of the evening with it using the Mother's Billet Polish. I figured it should look like a Queen if it was going to be a Queen.

I think it will feel more comfortable in one of my boats than trying to tractor a plane in the air.

It is laid out well for boat use with the rear facing carb, plus it's throttled which is nice. Most of the .049 boats never get to see a throttle.

One thing I wished Cox would have done is make it interchange with the .09. I do like the case layout, and it being a reed.

I'm hoping a good dose of castor and a few hot runs might seal it up also like Bob mentioned. Swelling the piston sounds like the backup plan.

Mr Cox

That only works on some engines though, guess it depends on how the piston has been made and what it is made out of.
It kind of worked a little on my CS 061, but once on a Veco 19 I think the piston actually schrunk...

Also on cox pistons it is hard to know how it will affect the conrod balljoint, does it go softer or harder?

jetpack

My Feedback: (1)

A hollow punch that fits nice around the inside of the piston might work okay if you peen around it like your setting the ball joint.

Its hard to think of a way to expand the walls near the top of the piston other than mushrooming out the top crown, plus there's always the center dimple on top of the piston also to have to work around. Too bad electroplating has to be ground to have a good finish.

Anyone experiment with home chrome plating kits that Micro-Mark sells? I think they sell another kind, copper plating. If the plating is soft would it really matter because it would only wear until it found its fit again?

combatpigg

My Feedback: (3)

If you could come up with something that works, it would be like catching lightning in a bottle.

A local C/L legend claims the cherry red method works. I tried it and got nowhere. Unless the process is controlled by someone who knows his stuff.......?
I think the piston could be heated and re-forged in a special die.

WINANS

I bought one when they first came out - enchanted by the novel layout. I built a canard to use it on, considering that it's a reedie and doesn't care which direction it turns. Swapped the muffler direction, and ran it on an APC 5.7x3 if I remember correctly. It ran wonderfully and provided TD .049 power at the well known weight disadvantage. But, it throttled very well.

Tried it on a couple of other airframes and larger props, where I found that it simply won't produce practical power with a large prop load (such as a 7x3).

Scott

flyinrog

My Feedback: (1)

I know I've said it before many times but the QB .07 is designed on purpose to have the power of an .049,, it was just made bigger so the carb and muffler would be effective, and they are...Rog

Mr Cox

Yes, I have heard that too. If an engine runs and throttles well but has comparativly low power, one could surely still find some use for it.
The first time I ran it though with stock head (not stock glow plug) it ran a lot weaker than a healthy 049. I didn't tack it then but it did not sound well at all. I think that was due to a very poor compression, if a head from a TD09 can improve on that it is an easy fix and that's what I'm suggesting that other people could try.

I have now also tried it with a graupner 6x4 prop. It throttles a little better perhaps but the top end sounded a little overloaded to me. When going from idle and up it would briefly show something around 16400 rpm (which is quite good in my world), this then dropps to something unstable around 15700-15800 rpm. When throttling down to cool off, the behaviour is repeated.

crossman

What is a good plug to use on this engine? Assuming that it has the original head.

Yuu

I think I like Combat Pigg's idea.... heat the piston, and put it in the conrod 'reset' cup, and tap it with a small pipe, id of pipe is big enough to NOT hit the ball socket. Guess method, might take several tries, but might expand the top of the piston a "little". What do you think, CP?

Mr Cox

Well that has been tried and didn't end well; http://www.rcuniverse.com/forum/m_71...tm.htm#7131630

If you grow the piston you then only have to make a taper in the cylinder and you'll be done...

Sounds much better then to fit a complete TD09 cylinder and piston, that only requires a "little work" on the conrod and that has been done by others I believe.

combatpigg

My Feedback: (3)

Yuu, I think it's possible. The outside diameter could be controlled with an exact fitting die.

The tooling to expand the roof of the piston without distorting the walls.....hmmm.

First, I don't think working the piston while it is red hot is good for the ball socket, rod, etc.

I think this can be done at a lower temp that makes the leadloy willing to stretch a little. If you can squeeze the roof of the piston with enough pressure evenly, that material has to go somewhere. A striking blow has to be precisely controlled, you would need to jig up a holding fixture for the striking tool. We just want a minute amount of metal to shift perfectly towards the outside and carry the piston skirt perfectly too, that's all.

A guy with tool and die making experience could probably get this done in his sleep. The leadloy steel is what makes this idea sound feasible to me. Just think, if you could develope a process where all it took was a quick hit and then a follow up lapping session to restore an engine in an hour or less. You'd still have to charge about $50 to make it worthwhile. It would still be better than buying replacement P/L sets that were rejects from the production line. If the fit can be made perfect enough, the engine will run OK even though the liner isn't tapered.

DeviousDave

It might also work to have the piston hard coated with something like Titanium Nitride. This is done in a particle vapor discharge (PVD) process, so there is no sloppy "buildup" like with chrome. I would call up a place like Balzers and ask them what the minimum coating thickness they can apply is. The punches that we have done for work typically grow .0002 (that is in Diameter, so .0001 per side) at a thickness meant to improve life of a tool that pops holes in coiled sheet steel.

The added benefit is that the piston will be Uber-slippery in a way that Chrome can't touch!

jetpack

My Feedback: (1)

Something like a split collar that can be dropped in with an inside working taper that can be punched to expand it.

Think of how tapered split collars work on car valves.

Hand working forces (punch and hammer) limits the working band height which is good. You're really not trying to expand the entire length of the piston...just the squish band of the top wall I would say 1/16".

Problem is the rod is always in the way with these things, so a hollow punch with a centerpunch taper has to be made.

TiN coating sounds wonderful, but a single piece cost I would think a new piston liner combo TeeDee Style would be in order.

DeviousDave

The problem is that he can't go out and find another cylinder for a Queen Bee. They didn't sell well enough to have lots of parts laying in hobby shops across America.

Personally, I'd leave it and run it until you couldn't stand it anymore. Something I wonder about is that I can't recall ever running a Cox that had an "ABC pinch at TDC", in fact, I just checked a brand new .010 and .020 cylinder to see if there was any pinch and neither had any. It could be the plug is the cuplrit, and you might be able to help yourself by increasing the squish band by turning a little off. Should be easy to do with the glowplug thread in there to hold it.