Schnuerle ported 049s

Marleysky wrote:Hey Gliderman, Welcome to the CEF!

Agreed, welcomed Gliderman to the forum!

Marleysky wrote:Scepter Flight shows a couple of tests on the TD. 049. I guess here is where I learn something: Td is front rotary intake, vs the Bee’s reed valve. Not sure what Schnuerle porting means.

For Schneurle porting see: revolvy.com: Schnuerle Porting

It was a way for improvement on the other porting systems, did away with the piston baffle on cross scavenged ported engines. The Tee Dee dual porting system with SPI, without piston baffle and various tweaks was IMO also efficient, why Cox was competitive for a long time since the early 1960's. Sometimes I wonder if with the inside of the cylinder chromed and a lighter aluminum piston would have improved performance further.

3rd port where the old Tee Dee exhaust port was would improve swirling of the fuel-air mixture I imagine. Cox was on its way to Schneurle ported engines with is Conquest series, but foreign competition and lack of sufficient importation tariffs to level the playing field led to the demise of nearly all US model engine production facilities. I imagine that the smaller engines would have followed suit in the Conquest series, too.
That would have been an exciting development but alas never happened. Anyway, my 2 cents.

I doubt you will come up with any performance stats on the KK engine as they were a custom thing. If you can find when Dale Kirn was producing them you may be able to look at old model mags for a run down.

I can’t imagine that they were a really big improvement over the standard porting as the ports would have been smaller than stock unless intake and crank work was done along with adding the third port.  Then there is the exhaust dilemma as where there was two there is now only one. It’s a fine line between too much in and not enough out. Although I have read numerous times that 2 exhaust ports on the Cox engine was overkill, so maybe it could still flow well with 3 intake and one exhaust port. Norvel engines run that configuration I believe and perform very well.

The TD Special .15 MKII has the 3 port and one exhaust configuration and it runs about 500-1K rpm over the regular .15 Special. If my memory serves that is. I have both and remember taching them using the same prop and fuel.

I too would be interested in hearing about how they performed.

Good Luck!

Ron

You have a good point, Ron. What I see is the limitation of the Cox cylinder. The bypass ports are rather shallow to retain sufficient strength to the cylinder. To deepen them would require a thicker liner. The milling process was developed for high speed production at lowest cost. I think it was the law of diminishing returns. There's not much more that could be done with the existing design for further improvement except start over with a totally new one.

Then too, there were failures along the way. We'd hoped for a much improved .074 when the Queen Bee arrived. Alas it was a reedy that was heavy, required special motor mounting and with the same power as the smaller Tee Dee .049.