Cox .074 Queen Bee

Hello Fit90
I did a search for a cox.09 turbo glow head and had no luck. I guess I will have to look for a TD.09 head. I want to make this engine perform better than factory. I bought a used .074 that turned out to be brand new. I took it apart to evaluate the engine. I think I can do some improving,already polished the crank. Thanks for the help.
Juan

Guys, let's give a warm welcome to Juan. Juan comes over here from StuntHanger!

Juan, show the group your latest Midwest P-40 clone build! You get bigger file shares here.

Hello Jim
         Here are a few pictures of my Midwest Mini Warbird P-40. All I had was the plan side view on a plan book I have but did some search and in a control line book by Dick Sarpolus I found a photo of the parts that I enlarged to build this little plane.
                                                                                                                        Juan
                                                                                                 an image.

WELCOME TO THE CEF!
Glad you found us here

Hello Marley
Glad to be here.
Juan

Welcome Juan!

I like what you did with the "snorkel" on the Sure Start

Are you going to use a balloon tank?

Welcome Juan, I want you to enjoy the good PEOPLE of this place.
Greetings to you

KariFS wrote:Welcome Juan!

I like what you did with the "snorkel" on the Sure Start

Are you going to use a balloon tank?

                 Hello KariFS
                                     I cut the snorkle at 45 degrees to get a little supercharging. As the air hits it is forced into the venturi. I`m going to use an oblong wedge uniflow tin tank I made.  Here is a pic. Hello From the island of Puerto Rico,Glad to be here.
                                                                                                                  Juan

MauricioB wrote:Welcome Juan, I want you to enjoy the good PEOPLE of this place.
Greetings to you

    Hello Mauricio
                         Glad to be here a lot of friendly people in this forum.Thanks.
                                                                                                  Juan

I like the wedge in the tank idea. I think the turbo plug head was made at home. That is what most guys do if they have a lathe at home. It is easy to convert a burned out head from an .09 or whatever you have. A 1/4 - 32" head does not have enough neat left, so the stock .074 head will not work easily. There are not a lot of mods on a reedy that make much difference for power beyond a bigger carb and a proper head. I wrote down a bunch of numbers with a Cox .074 with no muffler on 10% fuel . 16,000 with the TD .09 head. 15,400 with the stock 1/4" - 32 head. With the muffler I got 13,800 and 14,600, so the muffler sucks a lot of power. All tests used a 6 - 3.5" prop. I checked a few .074 motors that I have on the same day. A T Tiger was around 14,000 to 14,900 with a similar 6.3 - 4 prop, and the turbo plug head that I made up went up to 16,200. (Others went even better) So that was a worthwhile step up. A Big Mig .074 was 18,900 with no muffler and a 6 - 3.5 and a Gilbert .07 was 11,000. (That is even pre reedy days).

Hello aspeed
Thanks for the info I saved in my engine mods folder for reference. I wanted a tank that wouldn`t be too far from the engine and that was the shape that fit the bill. I have done engine work previously and will try to make a turbo head for the engine. I had a though time removing the Queen bee`s head,I tried applying heat and it didn`t work. I put the cilinder with the glow head in a plastic bag and placed in the freezer last night this morning the glow head came off real easy. Thanks again.
Juan

If you make a turbo head, I found that a 100 degree, or probably a 90 degree countersink makes a good combustion chamber on the .049s. I made them about .060" from the squish band to the surface of the turbo plug. An .074 maybe could be .075 deep or so? I used a ball cutter for the .07 T Tiger just to match the original shape. I think the thread size for the Turbo plugs are 8mm x .75mm pitch. A Nelson plug is good, but the size is very odd and expensive. The taper for the turbo plug is 60 degrees and minor diameter would be 7.25mm. I used a 1/4" countersink and backed it away the proper amount to give the diameter.

welcome, and I like your p40 alot

Welcome,

The P-40 is one of my favorites. Love the custom tank.

"I'm 70 years old but have been a kid all my life."

X2 on that.

Bob

Hello Bob
I hope to be posting pictures of the finished plane soon.
Juan

That tank is pure beauty!