DA 120 on Cans and prop selection

[chishp]

Hi Jim I have just put together a Hangar 9 33% Pawnee with a DA 120 with TD 80 K canisters on straight pipe headers running a 3-blade 27x12TH Mejzlik prop interested in your comments re the above? if we get a fall off in performance we should go to a 3 blade 26x10TH. ?? or do you think the latter canisters will not have the same problem?? Interested in your opinion. What oil ratio do you run?
regards
Paul Chisholm
NZ

[JimD]

Hi Paul,

We have had multiple tow planes using DA-120 on MTW canisters and found that the peak performance was with a 2-blade Falcon 27x11 carbon prop. That is not the quietest setup, a 3-blade would be better there.

The 3-blade 27x12TH Mejzlik should give you about the quietest operation, but for towing larger heavier sailplanes the 26x10TH will give better performance because it will allow the engine rpm's to stay up in the power band.

As for canisters, they have a life-span. Over time (approximately 100 hours) carbon build-up inside will decrease flow through and cause a loss of power. There is no real good way to clean them out, so they become scrap metal at that point. Quiet comes with a price!

DA recommends RedLine 2-stroke Racing Oil at 40:1, so we follow that recommendation. I did not do this on my first DA engine back in 2010 at soon had a problem. Fortunately, DA restored the engine to new condition and every since we have done what they recommend!

Hope this info helps,
JimD

[chishp]

Hi Jim,

Many thanks for your opinion and advise currently running on 40-1 redline racing oil and will continue to do so.Your points re props are noted
regards
Paul

[chishp]

[JimD]

That is a fine looking Pawnee you have there!