L2-B w/C-85 prop

[Pete Eslick]

Hi everyone again. What is the best wood prop size for an L2-B with a C-85? The Sensenich charts don't address the exact combination, and I'm certain the subject has been addressed before. I am most interested in climb performance, cruise is secondary. Also, I'm in Florida, so the elevation is essentially sea level, and summers are hot.

[Ragwing nut]

Re: L2-B w/C-85 prop

72-42 or 44

[d.grimm]

Re: L2-B w/C-85 prop

I don't have a L2, but I do have a 85 hp Vagabond that
I also wanted climb performance. A Sensenich W72GK44
Is what you want. Make sure it's a GK so the engine can spin
Up for max power. I get 2400 rpm on takeoff and can slightly
over rev at max power cruise. If you have the O-200 crank you probably
want the 42, but you have a lot more than 85 hp.
Dave

[n6346m]

Re: L2-B w/C-85 prop

I have a 72GK48 on my L2-B with the C-90 Certified Aeronautical Products STC conversion. I really like the performance it gives. I'm afraid that any less pitch and the Static RPM will exceed the static RPM limitations of the STC. I climb out at 60MPH and I have to pull back the power so as not to exceed RPM redline. I just ordered a new one from WAG-Aero and the lead time is 8 weeks. Be sure to get a 72GK propeller, not the more common 72CK as they are not legal for the C-85 or the C90.
Bob

[N95334]

Re: L2-B w/C-85 prop

What is the difference between a (GK) and (CK) You are talking about wood props correct?

[Ragwing nut]

Re: L2-B w/C-85 prop

GK and CK was the old nomenclature to identify hp ratings between 65 and 85 hp propellers. The difference is the old CK was 4 laminations and GK was 5. I do not know if they are still that way, or they are now all made the same. The C90 has a lower rpm redline at 2450 where the 85 is 2575

[jim cooper]

Re: L2-B w/C-85 prop

You MIGHT want to ask around, the difference between wood and metal. There is one. The MCcauley metal prop on a 65 or 85 will make a difference. Its more efficient. IF Taylorcraft had not been under such financial pressure during their life, I feel certain something like the Super Cub would have evolved and it would have been terrific and it would most likely had a metal prop. If climb is important I hope you check with others before deciding. East Coast propeller sells both brands. Randy is the manager and knows his props. Good luck, JC

[n6346m]

Re: L2-B w/C-85 prop

What is the difference between a (GK) and (CK) You are talking about wood props correct?

Horsepower. According to the Sensenich Propeller TCDS, the CK is not certified for 85 or 90 Horsepower. It doesn't say why but I suspect that the GK is built a little stronger to allow for the extra horsepower and RPMs. It could be the type of wood or numbers of laminations or type of glue or even the testing procedure. You would have to ask Sensenich about what makes them different.
The prop I use is a W72GK48. "W" is for wood, "72" is the diameter "GK" is the model and "48" is the pitch.

[n6346m]

Re: L2-B w/C-85 prop

Please correct me if I'm wrong. I just looked up TC E252 (TCDS for the C-90) and the max continuous RPM for 90HP is 2475 and for 95HP it is 2625 for take-off limited to five minutes maximum.
One of the reasons that I chose the C90 over the O-200 for my engine conversion is that there is no wood prop currently available for theO-200. There are advantages and disadvantages to each type. I fly with a metal prop in the summer and a wood prop in the winter.

[jim cooper]

Re: L2-B w/C-85 prop

Please correct me if I'm wrong. I just looked up TC E252 (TCDS for the C-90) and the max continuous RPM for 90HP is 2475 and for 95HP it is 2625 for take-off limited to five minutes maximum.
One of the reasons that I chose the C90 over the O-200 for my engine conversion is that there is no wood prop currently available for theO-200. There are advantages and disadvantages to each type. I fly with a metal prop in the summer and a wood prop in the winter.

I Fly with a metal prop in summer, wood in winter.....Why?

[d.grimm]

Re: L2-B w/C-85 prop

The difference between a CK and a GK is
the GK prop has a narrower chord so the
engine can turn up to a higher rpm. Side by side
the difference is very obvious.
Dave

[n6346m]

Re: L2-B w/C-85 prop

I Fly with a metal prop in summer, wood in winter.....Why?

The main reason I use a metal prop in the summer is that I believe that the metal props are slightly more efficient than the wood props. The L2-B is not a fully cowled engine with most of the engine sticking out in the breeze like pre-war T-Craft and J3 cubs. Without the ability to limit the airflow over most of the engine by partial blocking of the air intakes, it is impossible to get the engine/oil temperatures anywhere near normal. I have flown all winter when the oil temp gauge never came off the bottom peg of 100 degrees. Yes, I have tested it and it works just fine in the summer. Other than the usual insulated oil tank and intake tube covers there's not much you can do except change the prop. Aluminum propellers bolted to the crankshaft are great heat/cold conductors and make a great heat-sink especially spinning around in 10 below weather. Wood is not a good temperature conductor and helps keep the heat in the engine. In addition, I understand that you can lose up to 20% of your heat through the metal prop if you use an engine cover without using a prop cover. With a wood prop, I don't use a prop cover for short layovers or pre-heat. In addition, winter flying on skis has it own hazards. Having no brakes, hidden hazards under the snow, overflow ice at Lake Hood can turn your prop into tooth-picks but it can also save you an engine tear-down. By the same token, If I lived in a hot climate, I may want to use a metal prop all the time for the additional cooling.