COX .05 R/C

Balsabug Thu Sep 17, 2015 10:11 pm

Hello to the Cox Engine nation!!! This is my first post. I have a question about late model Cox Engine crankshafts and pistons. First, I am a Free Flight enthusiast moving back into 1/2A power duration and have kinda started where I left off back in the early 90's when Shurikens began eating up TD's and Stels engines on the flight line. I was building hopped up TD's. I know Pecco's, Profi's, Fora's and Cyclons are the hot engines of our day now but I still love a hot Tee Dee on a 6oz ship.

Okay my question is this: Did Cox build lightened versions of the standard race-timed Tee Dee crankshafts (drilled out journal and ground in flywheel arcs) for the COX .05 R/C engines and did they use standard .05 pistons that weigh 3.2 to 3.3 grams each

-OR-

Did they build a special lightened, yet heavy duty looking competition crankshaft with drilled out journal, shaved smiley and two ground in flywheel arcs on both sides of the journal. Were they also outfitted with lightened piston via boring, weight unknown but more than likely 2-3 tenth's lighter?

I have in my possession a "New" COX .05 with a modified standard race-timed crankshaft and stand weight piston which to my knowledge is incorrect. But I don't know everything. A humble plead for clarity. Thanks in advance.

NEW222 Thu Sep 17, 2015 10:30 pm

Sory, as I cannot answer your question, but I would like to be the first to welcome you to the C.E.F. I am sure that someone will be able to help you out.

balogh Thu Sep 17, 2015 11:58 pm

Balsabug wrote:Hello to the Cox Engine nation!!! This is my first post. I have a question about late model Cox Engine crankshafts and pistons. First, I am a Free Flight enthusiast moving back into 1/2A power duration and have kinda started where I left off back in the early 90's when Shurikens began eating up TD's and Stels engines on the flight line. I was building hopped up TD's. I know Pecco's, Profi's, Fora's and Cyclons are the hot engines of our day now but I still love a hot Tee Dee on a 6oz ship.

Okay my question is this: Did Cox build lightened versions of the standard race-timed Tee Dee crankshafts (drilled out journal and ground in flywheel arcs) for the COX .05 R/C engines and did they use standard .05 pistons that weigh 3.2 to 3.3 grams each

-OR-

Did they build a special lightened, yet heavy duty looking competition crankshaft with drilled out journal, shaved smiley and two ground in flywheel arcs on both sides of the journal. Were they also outfitted with lightened piston via boring, weight unknown but more than likely 2-3 tenth's lighter?

I have in my possession a "New" COX .05 with a modified standard race-timed crankshaft and stand weight piston which to my knowledge is incorrect. But I don't know everything. A humble plead for clarity. Thanks in advance.

Hi Balsabug, welcome to the forum.

I guess this will answer your question:

I have 3 genuine TD050-s and they all feature this crank design. Given that only 2000 pcs of this gem were made altogether I do not think COX built them with a varying choice of parts, but all were made to the same design. The piston is not lightened either.

Balsabug Fri Sep 18, 2015 8:48 am

Okay I see. Thanks for the confirmation. So I guess the other crankshaft and piston I am talking about came installed on the Helicopter engine only? (It looks similar to a Venom or Killer Bee crankshaft).

balogh Fri Sep 18, 2015 9:05 am

I am not sure about your crankshaft, but the lightened piston which is shorter than the normal cannot work in a TD050 which has inherently been designed with non-SPI porting because of the muffler.

Balsabug Fri Sep 18, 2015 9:43 am

It's the crankshaft I am really interested in. I would not be running the engine in it's current configuration anyway. Thanks for your comments!

1/2A Nut Fri Sep 18, 2015 2:35 pm

I used the performance crank with a Killer Bee Piston here are my result I call the engine a Killer TD.

The Killer TD .049 - Cox RC carb
Breaking in the engine in the air
Galbreath / Nelson plug
#1 cylinder 2 bypass ports 1 boost flute per port
2nd flight APC 4.5 x 4
22,044 rpm in the hand static - 25% nitro
best pass at 24,160 rpm 3rd fastest set up -needle is set bit rich. 67 F. winds 6 to 9 mph

Killer TD .049 3rd flight
APC 4.75 x 4
20,873 rpm in the hand 25% nitro
22,287 rpm cross wind and 23.94k down wind
9 to 12 mph winds - temp 78 F Humidity 80%

Stock TD .049 - Cox RC carb - Cox High Comp plug
APC 4.75 x 4 (no data with the 4.5 x 4)
19,380 rpm in the hand 25% nitro
21.4k rpm cross wind 23.3k down wind.
Winds about 4 to 6 mph per hourly weather check. 74 F

TD .050 RC #5 cylinder- high compression head 1 shim - 1st flight test
performance crank non SPI - 140 deg exhaust timing 25% nitro 78 F
Tarno carb - APC 4.5 x 4
In the hand 21,237
unloaded 23,771 best pass / 90 mph theoretical
In a down wind high dive 24,9K 94.3mph

Balsabug Fri Sep 18, 2015 2:41 pm

Great info, thanks-

1/2A Nut Fri Sep 18, 2015 3:46 pm

Here you go first flight test with the speed crank and the lighter weight performance piston.
Note they used these cranks on the Litemachines Helicopter back in the day prior to going with the Norvel.

Published on Apr 5, 2015
I am breaking in the engine in the air with a APC 4.5 x 4
This is the second engine run 22,044 rpm in the hand and best
pass at 24,160 rpm needle is set bit rich. After a few more runs I expect a fully broken in engine getting about 25k needle peaked.
Engine includes a V shape flywheel with the rod pin drilled out originally made for the TD .050 RC to up rpm for a none SPI engine using a muffler - Note I am using a Galbreath glow head with Nelson turbo plug. The Killer Bee is a original May 1995 engine bought new never used. I robbed the tapper piston and cylinder for the TD frame comes with SPI function which can be heard on start up with a notable tone clearing burst of power. Note the Killer Bee has a lighter piston weighs .5g less than a stock .049 piston. Installed a phenolic thrust washer for electric starter use. This will be a two part vid for reference once the engine has been broken in a follow up video showing the final results using crank case pressure.Run time in rich mode 1oz fuel tank 25% nitro 5mins 44 sec. 11.4 oz plane 5 ch with flaps / rudder / ailerons / throttle / elevator.

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