Screws For Bee Backplate Mount

Thanks for the confirmation. Just what I wanted and needed. I guess I will pop out the blind nuts now.

Could it have been equipped with an RC Bee or a Dragonfly? I think their mounting pattern is the same as on other Bees but the holes are bigger.

Oh. Something I had not thought of either. Could be a good guess as well.

The info. I found on this kit/model shows FRV engines. Was yours built for a reed-valve engine? Either way.. what would work.. is a 3-48 machine screw. The package that I just sent your way actually has some black oxide cap-screws that are 1" long. I sent them because the Cox .020 engines use a 3-48 prop screw.  

Dubro used to stock 3-48 blind-nuts..



I'm actually wondering if there may have been a nylon "beam-style" engine mount that mounted radially to the model's firewall.. possibly with the 4-40 screws??



In that case, it might have had a .049 Medallion or Tee Dee for power.

Nonetheless; 3-48 machine screws are a perfect fit for OEM Cox .049 "Bee" series backplate lugs.. and also the mounting-holes on the Medallion/Tee Dee .049/.051 engines.

FYI; the nylon beam-style mount shown I sourced from EXModel engines.

I can take a peek at the LHS for 3-48 hardware, but if memory serves me correct, I had looked for some there before and they had nothing available. But never hurts to ask. Thanks.

RTL Fasteners will have anything you need, fastener wise.  Here's a link for 3-48 screws. Their assortments are great too.

https://www.rtlfasteners.com/RC/1633.html

I was thinking maybe a Tee Dee tank mount or Dragonfly may have been installed, but I just checked my stuff and while the bolt patterns are close, both are different from a Bee backplate as well as different from each other. Don't know if that's any help, but there it is.

Nope. That was great help. It at least eliminates one possibility. Thanks for checking.

And on another note..... So I looked at the engine that will be going on the plane and saw very light thread marks inside of the ears on the backplate, having me now believe that the engine was also mounted at one time with 4-40 screws. So I took a 4-40 screw and was able to 'thread' it into the mounting holes with only my fingers and no pressure until I could no longer screw it in with my fingers. Funny thing though, when I used a micro screwdriver to finish it off, it was freely spinning in the hole, but does not freely push out, but threads out with no pressure applied? Wierd. But since the screw went in like that, I am going to mount it with a 4-40 as I have them available and see how it feels.

And after looking at the plane again closely, I would not get the other hardware in the plane without doing some surgery! The holes are higher up on the firewall, behind the upper cowl about 3 inches and under the dash. I could not see nor feel anything close. The only other option is may have available is to drill new holes lower than what is there and either thread the plywood or use just small wood screws. Any opinions on doing this?

The mounting hole pattern of the TeeDee049 nylon "beam-style" mount is different than the pattern the Bee or other tanked 049-s have. The former has the mounts in the corners of a square i.e. width and height of the screw pattern are the same. Bees, however, have the holes on an oblong but not square pattern and the distance between the holes is also different than on the Tee Dee 049 mount. So it is easy to identify if the original COX engine was a tanked reedy or a TeeDee, simply based on the mounting pattern.