Medallion .09 Throttled clean up

Thats a loong time ... But as was said the reg,HI comp . heads work good here .. for .049s dont know bout the .09s though , haven't ran it enough i am sure.. It is interesting to hear this though..

Yes, it will be interesting to see how these different heads perform on the Medallion .09. I just noticed the odd thing about the .074 QB is the stepped prop hub designed for mounting larger prop hubs than the ones for the .049's. It looks like it ought to mount 7" and larger props. Yet the QB's recommended prop is 6x3, which is down in the .049 class. Masters 6x3 doesn't have much meat to clamp in the partially hollow prop hub area after reaming to fit. APC has a 6x3 that appears to have the larger hub with larger mount hole.

sceptreflight.com May 1989 Cox 074 Queen Bee

I need to rebuild Q-Tee from a crash. The Norvel .061 Big Mig with Norvel mount tank wasn't heavy enough so it was slightly tail heavy. (Old days we put the 4 AA pen cell Ni-Cad pack up front, which balanced it with a Black Widow for power.) I think the QB would be a good choice, as it also compensates for 4,300 feet elevation power loss, and adds some zip to this sport plane.

The Queen Bee certainly is an odd engine, it seems most happy on a 6x3 prop, but doesn't make much power for a .074 engine. A 6x4 sounds good, and it throttles nice, but the engine seems to over heat a little. The 6" graupner props fit the propdriver directly without any modifications to the prop, it is almost like they have been matched on purpose.

Here are some numbers for the Queen Bee on 10% nitro and 20% all castor;

Graupner 6x3; 17000rpm
Graupner 6x4; 15800rpm (it reaches about 16500rpm initially and then drops)

As a comparison the Cox TD 05 RC will do about 17200rpm with the same 6x3 prop and fuel...

Surfer_kris wrote:The Queen Bee certainly is an odd engine, it seems most happy on a 6x3 prop, but doesn't make much power for a .074 engine. A 6x4 sounds good, and it throttles nice, but the engine seems to over heat a little. The 6" graupner props fit the propdriver directly without any modifications to the prop, it is almost like they have been matched on purpose.

Thanks for the tip, Kris. Unfortunately the Graupner props for engines are hard to obtain here in US. Tower Hobbies no longer carries them. APC does make a sport prop in 6x3, which may be a good alternative for me.

Here are some numbers for the Queen Bee on 10% nitro and 20% all castor;
Graupner 6x3; 17000rpm
Graupner 6x4; 15800rpm (it reaches about 16500rpm initially and then drops)
As a comparison the Cox TD 05 RC will do about 17200rpm with the same 6x3 prop and fuel...

Thanks for the numbers, Kris, they illustrate that the power of the .074 is similar to the Cox .049 / .051 Tee Dee's, as the writers (articles available in Sceptreflight) did indicate with the 6x3, it throttled nicely. I just found it odd that the prop hub was designed for larger props but engine was suited for half-A ones with overall smaller hubs.

The drawback to the engine is its extra long length and heavier weight, which is a drawback in half-A models. I've always wondered why Cox didn't simply upsize the Sure Start with venturi back and a lighter exhaust restrictor muffler, extruded bar machined crankcase. The cylinder appears to be a modified Cox .09 with undersized bore and SPI eliminated. A .09 exhaust restrictor muffler would fit with very little modification. It would have been cheaper to produce and be lighter in weight, not to mention the same net results in power.

Interesting variants could be developed like a .074 Killer Bee, .074 Texaco, .09 Sure Start and etc. I gather than some of the decisions made toward the latter part of the Cox company (like introduction of the R/C Bee [with its cast crankcase instead of tried and true extruded] and Queen Bee as implemented) indicated its days were coming shortly to a close.

A dozen J&Z Zinger 6x3 wood came in a couple days ago,



followed by 14 NOS Tornado 7x2 wood props today.



These must date back a while ago. The craftsmanship is excellent, there is raised die embossed words on the front by the hub, "15" above right and "Series" below left, a "2" on back, hub front has very small embossed letters .... after looking over several, hard to make out as about 1/32" high letters, appears to say "Grish Product" on top with "Made In U S A" on the bottom right on the hub.

When was the last time anyone saw 7" wood props at an MSRP of $0.20 each? (As an 11 YO I vaguely remember Top Flite half-A nylons for around $0.25 in the mid 1960's at the hobby shop at Keesler AFB, Biloxi, MS.)

I want to test these 7x2's out on the Cox .074 Queen Bee. Their larger hub is a natural fit for the larger hub. I've been thinking the possibility of fitting the Berkeley Impulse with the QB as it has a longer needle valve, which extends past the cheek cowl without modification. It's power would be akin IMO to the Fox .09 Rocket side port. As it is an odd plane, the odd looks would be cool.

An interesting thing I noted is that the QB nose spinner is slightly larger in diameter than the Cox .09 one that I bought from Ex Model Engines. (Cox International one appears to be the same.) These I can't swap without modifying, because the QB has a narrower prop screw than the .09's.



As the QB spinner is still available from both, one could simply drill out the hole for the larger .09 screw and mount to Medallion or Tee Dee. I think the slightly larger size looks cooler.

Nice looking props George , i had ordered some woodie 8x6 and when i got them they were LH i didn't look close enough at the pics and he new nothing about them . I just sent them back and am looking at some Zinger and TF 8x6 at around 150-175- apiece , they are New ! Is that Berkeley Impulse a pylon racer from the 50s? /// That's a heck of a deal for .20 apiece if i read that right

getback wrote:Nice looking props George , i had ordered some woodie 8x6 and when i got them they were LH i didn't look close enough at the pics and he new nothing about them . I just sent them back and am looking at some Zinger and TF 8x6 at around 150-175- apiece , they are New ! Is that Berkeley Impulse a pylon racer from the 50s? /// That's a heck of a deal for .20 apiece if i read that right

Thanks, Eric .Prop cost for the 7x2's came out to $2.13 apiece. In 1950, $0.20 was equal to $2.03 in todays US dollars, which is about right. Goes to show with inflation, how much our money has degraded in value. Back then they didn't have numerical control machinery to make props. I imagine they had various jigs to manually mill the props through a multi step process, probably on an assembly line. I was impressed how well these are formed, milling is definitely superior to modern props, especially around the hub.

(Sticks were trimmed to length, another drilled the prop hole, another the back side of the blades, another the front side, another sand and stamp embossing, another stack multiples on a jig, another to spray lacquer / dope, another to carry racks to drying area, another to remove from racks, another to grade and QA, stack portion goes to boxing with other to rework or reject, another to package, another to box, etc. I am imagining how this could be done, never read about it. They made these by the tens of thousands annually.)



Yes, it was billed as a trainer or single channel pylon in 1959, at 46" wingspan and plans show a Fox .09 Rocket on it (power of a hot .049 of the era). Having flown single channel, I can see how this can be done. By properly trimming and shimming the trailing edge of the wing to decrease decalage, during windy weather of 15 MPH I could still fly rudder only. Only thing is it limited its climb. slightly more aggressive turns would hold altitude, a little more would decrease it. I was flying may be 70 feet off the ground, but still flying. It made the glide a bit quicker, but flying over tall grass would minimize any landing damage.