racing at6?

cmulder wrote:Made up a "kinda killer" bee from a kb backplate, td piston/liner and for good measure added a trust washer behind the prop drive plate.
Crank/case is stock sure start version
These have the same dimentions as a product engine so put it in a at6  "'texan" and also found a apc 4.75 by 4 prop and  put it on.

Is this a good idea?
Will it fly ?
Will the heat from the engine damage the plastic?
Will it be to powerfull and fall apart during flying?

What do you guys think?

I built a killer bee clone like yours and it is very powerful. I would remove the cam starter which robs some power that you reached with the TD piston and cylinder,  and add a conventional frictionless starter spring. You may up the engine further with a turbo head like Kamtechnik.

You may also make your own exhaust deflector cut from a beer can or similar,  to protect the plastic from the hot flue gases.

A really nice looking Texan and a great fix on that vertical stab.

Bob

I have a exhaust deflector made by cox that goes between the backplate and crankcase; would that work or make a ring that forces the exhoust to be pushed up?

The stock COX deflector that goes between the crankcase and backplate will disperse hot gases and castor and will protect the plastic parts from melting...do not even dream about a perfect castor splash control unless you have a completely closed muffler, and even with the outlet directed away from the plane will not help prevent castor to smear your fuselage..a closed manifold connected to a Profi tuned pipe is the ultimate solution.

But this is how we like our COX engines slinging castor, isn't it?

I have looked on the Cox International site and cannot see an exhaust deflector. Are they a part that was once available as a standard Cox part but now no longer available. are they a part that will fit on a Surestart grey backplate and crank case? I have seen various Cox mufflers but never a deflector plate.

Yabby wrote:I have looked on the Cox International site and cannot see an exhaust deflector. Are they a part that was once available as a standard Cox part but now no longer available. are they a part that will fit on a Surestart grey backplate and crank case?  I have seen various Cox mufflers but never a deflector plate.

It should fit. They were designed to fit the back of the standard extruded crankcases, thin sheet steel in design not requiring lengthened backplate bolts, so I can't see why they would not work.

The stamped blued spring steel exhaust deflectors were available some years back on Bernie's site. But, like in all popular items, sold out quickly, ditto with Matt's site. However once in a great while, they may locate a viable source (someone has a stash, willing to sell them wholesale and demand appears to be sufficient), they will sell.

Question is, when will the likelihood of this again occur? Perhaps a question for Kamtechnik to possibly explore making a suitable substitute?

Yabby wrote:I have looked on the Cox International site and cannot see an exhaust deflector. Are they a part that was once available as a standard Cox part but now no longer available. are they a part that will fit on a Surestart grey backplate and crank case?  I have seen various Cox mufflers but never a deflector plate.

hi priced https://www.rcnz.com/categories/fuel-engine-parts/cox-engine-parts/cox-049-exhaust-deflector-shield/

Yabby wrote:I have looked on the Cox International site and cannot see an exhaust deflector. Are they a part that was once available as a standard Cox part but now no longer available. are they a part that will fit on a Surestart grey backplate and crank case?  I have seen various Cox mufflers but never a deflector plate.

Hi Gary, Here's a couple photos of a Cox exhaust-deflector for the reed-valve .049/.051 engines. Cox International used to offer these.. but I don't know if they're still available. Making one from thin metal wouldn't be that difficult though.





Keep in mind; this only deflects the hot gases from "one side" of the cylinder.. and was intended to keep the user from burning their fingers while adjusting the needle-valve.. assuming that the needle was directly behind the cylinder.. and a cylinder's exhaust-port was facing the needle.

I can see how one could manufacture one from the aluminum of a soft drink can, by careful crafting using standard hand tools. Plus, they could extend the shielding to further protect plastic or painted surfaces from the heat of exhaust and hot Castor oil spatter.

I have even noticed on some photos of Bob @rsv1cox's Cox, earlier Wen Macs, and 1963 A.C. Gilbert RTF's, that unmuffled, they being historic survivors of many successful flights, suffered from plastic deformation behind and around the engine.

roddie wrote:

Hi Gary, Here's a couple photos of a Cox exhaust-deflector for the reed-valve .049/.051 engines. Cox International used to offer these.. but I don't know if they're still available. Making one from thin metal wouldn't be that difficult though.

thanks Roddie! Now I understand what the deflectors are all about. I knew I was missing something somewhere and not understanding

getback wrote:

Yabby wrote:I have looked on the Cox International site and cannot see an exhaust deflector. Are they a part that was once available as a standard Cox part but now no longer available. are they a part that will fit on a Surestart grey backplate and crank case?  I have seen various Cox mufflers but never a deflector plate.

 hi priced https://www.rcnz.com/categories/fuel-engine-parts/cox-engine-parts/cox-049-exhaust-deflector-shield/

You're talking NZ dollars, so USD will be significant less.

Oldenginerod wrote:

getback wrote:

Yabby wrote:I have looked on the Cox International site and cannot see an exhaust deflector. Are they a part that was once available as a standard Cox part but now no longer available. are they a part that will fit on a Surestart grey backplate and crank case?  I have seen various Cox mufflers but never a deflector plate.

 hi priced https://www.rcnz.com/categories/fuel-engine-parts/cox-engine-parts/cox-049-exhaust-deflector-shield/

You're talking NZ dollars, so USD will be significant less.

$10.00 NZD = $6.31 USD = $1331.16 ARS (Argentine Peso) = €5.76 EUR = $8.51 CAD = ₺121.64 TRY (Turkish Lira).

One thing i was wondering about adding this deflector is that it adds to the clearance between the crankpin and the backplate.
Is there no aditional risk that the conrod moves back and part off the crankpin?
This might lead to increased loads and wear.

batjac wrote:A few years ago I took two of the yellow "Manits" Wings planes and set them up for my son and I to run on the paved circle out at our club for some informal racing, as I wasn't up for doing true 1/2A racing.  Just think if we could get three guys together in the circle with three of these T-6 Racers....



The Speed Demon Mark

With these models its so easy to change the engine so you could have a "stock class" race and then change the engine/prop and have a "unlimited" race class with the same models
Also because there are red and black at6 versions people could make color combinations that stand out from eachother.