Too many COX engines hoarded for too few planes..

Counting only my COX engines, my cylinder index has well exceeded 70 already, and I am wondering how I could allow as many of my COX engines fly as possible in my not too high number of workable R/C planes..

So I decided to design the engine firewall of my recently built R/C planes so as to accommodate the most possible back plate and engine mount hole patterns on the same firewall.

The situation with TEE DEE 010 and 020 engines is relatively simple, because they each have only 2 mounting holes, so swapping them between the Roaring 20 (pictured here with an 010 in the nose) and the LilStick (designed for an 010 but powered by an 020) is not a big deal, and takes only placing 4 wood nuts on the proper pattern. The firewalls of my 2 planes below are fashioned to take any of the 010 or 020 engines:



The issue is more complex in the 049..050...051 engine range, that comes with postage stamp, or horseshoe, or TD mount hole patterns of which typically only 2 types (any combination of the 3) can be accommodated on the firewall.
The narrow firewall in my Lil Roughneck can easily accommodate the originally designed TeeDe020, but I have always flown this birdy with my home-assembled TeeDeeReeDie (a Killer Bee clone):



The Toucan was originally built for TD049/50/51 engines, but my curiosity to try the postage stamp O49 drove me to build an adaptor piece and swap the TD051 with the small reedy :



I am also experimenting with the use of TD049/51 as well as horseshoe backplate reedies on my fast TeeDeeVooDoo..



...the nose had to be drilled at multiple locations to make this engine combination possible. This is how the TeeDee mount was fitted in the nose....the empty hole serves as lead-out for the throttle pushbar with TeeDee-s, or, one of the stock mounting holes for the horseshoe backplate



...and the  mounting hole patterns for both the TeeDee049 and the horseshoe backplate 049 reedy:



The Black Lynx I won in January 2018 also mounts on the TeeDeeVooDoo thanks to the multiple holes I drilled in the firewall:



...and a TeeDee R/C setup (later I removed the entire muffler as it was counter-productive with a TeeDee049 having  an SPI cylinder):





The alternate use of TeeDe049  and TeeDee 09 was made possible on my Cosmic Wind, where, with 2 additional holes drilled into the 09 mount, and with the widening of bottom mounting holes on both mounts, the firewall mounting hole pattern was made common for the 049 and 09 engines, so with only 4 mounting holes in the firewall, I can put both in the nose ...both pull the Cosmic Wind with decent authority

...the mounts with common mounting hole pattern:



..the 049 powerplant in the nose:






...and the brute force 09:



..and a close-up on the 09 with exhaust deflector added, as seen today:



The original 09 mounting hole on the upper right of the engine mount now serves as lead-out hole for the throttle push-rod for both engine sizes. The 09 mount is fixed on the firewall with the new 2 holes drilled overlapping with the same upper holes on the TD049 mount, and with the 2 bottom holes widened overlapping on both mount sizes.  .


As I grow older and develop various allergies to CA glue, and my eyesight is not improving either, I assume I will not build too many planes in my remaining active years, but at least will try to allow most of my COX gems to fly as described above.

I love all my COX engines and R/C planes and feel guilty when some of them are left sitting idle for extended periods...