TD .049/Medallion .049 differences

Yes sure, there would be some minor differences to those curves depending on the fuel etc. But the graph shows most of the important trends very clearly. The early Babe Bee with a single transfer (and small venturi bore) are down on power compared to later bee's with dual transfers and larger bore (killer bee). All reed engines have an upper limit though in the rpm where the reed is the limiting factor. To get higher power you need a higher operational rpm and that's what you get with the TD (large intake and a large bore in the crank).

The medallion has a better fuel draw and makes for a better sports engine than the TD which is all about maximum HP and needs pressurized fuel delivery etc.

"i caught that two puffie40, someone should do this cox engine power graph with all the same settings, ie the same fuel content and the same size prop" - mitch

Mitch: Remember that differenent engines are designed for different purposes. What is good for one may not be good for others. Not all engines are "created" equal.

SuperDave wrote:"i caught that two puffie40, someone should do this cox engine power graph with all the same settings, ie the same fuel content and the same size prop" - mitch

Mitch: Remember that differenent engines are designed for different purposes. What is good for one may not be good for others. Not all engines are "created" equal.

Yup you won't win a texaco event with a mouse racer :-)

nitroairplane wrote:

SuperDave wrote:"i caught that two puffie40, someone should do this cox engine power graph with all the same settings, ie the same fuel content and the same size prop" - mitch

Mitch: Remember that differenent engines are designed for different purposes. What is good for one may not be good for others. Not all engines are "created" equal.

Yup you won't win a texaco event with a mouse racer :-)

good point, although it would be funny to see someone try

Well I mean with the right prop yo could definitely climb quicker

I think the nitro content is one variable that is not normalized and makes the chart unreliable. That is unless you had read the original MAN or Aero Modeler text. IIRC they did try to have a standard prop dia and pitch but I cannot attest to that.

I have operated several motorcycle and large full chassis dynos and fully understand the variables and relationships to HP, a calculated value, and Torque a direct measured value.

I personally think the chart is of little value for true comparison other to note that there are differences and the TD does have a more robust power band.

I dare say you could take the same engines and tune each to the correct nitro and prop combination to bring all .049s in the series to very close maximums and the anomalous TD reading would not be a distinctly different

One of the current magazine writers uses a computer controlled engine test stand that measures thrust, cyl head temp, rpm, and barometric pressures. I trust his/those comparisons much more than the simple tests from the 60s

Back to the topic... I believe the TD series included a 128TPI NVA while the Medallion series used the standard coarser thread NVA

No the medallions used a fine thread needle it is killer bee compatible.

Yes, there is more info to read in each individual test (including rpm readings for different props). I really like the performance curves though and the direct comparison between the different cox engines. The TD was by far the strongest .049 engine at the time (here with an even higher power than the tests shown above);

Ta da!

"I'd like start a discussion as to why. You first. This could be very informative for all." - SD

Have I accomplished my mission????

SuperDave wrote:

Have I accomplished my mission????

I don't know, is there any new information here?

Kris:

If this forum were only about "new information" it would not be as active as it is. For anyone new to the Cox hobby 'recyled" information is helpful.

Smile and be happy!

Educate the newbies!

And that includes me.

Surfer_kris wrote:

SuperDave wrote:

Have I accomplished my mission????

I don't know, is there any new information here?

I guess it depends on the reader.
I'm sure there are some newbies who gleaned plenty
of info that was new to them.
I like Dave's idea of getting more Cox knowledge out
there for everyone to absorb, even if it seems pedestrian
to some of us.
Mission acomplished.
Bob

microflitedude wrote:Educate the newbies!

And that includes me.

+1, i want to find out more

try this link for more information:

http://en.wikipedia.org/wiki/Cox_model_engine

it is warrens site