150-200cc Extra 300SP

[jamesrxx951]

Field pics

 

[Jetpainter]

Nice!

 

[Islandflyer]

James, your baffling should be fine, with the opening in front of the carb.
I chase engine problem on my one of 100cc planes for a while: the cylinder temperature was fine, but it turned out that the carb was getting hot.
After I opened some slots at the bottom of the cowl, it ran fine.

 

[Tseres]

This is the cowl Herve is talking about.

 

[jamesrxx951]

Thanks Tom. I thought the root cause of that specific issue was on a 35% plane with a smaller cowl using a DA120 and stock mufflers. Large source of heat. The 123" seems to have great airflow over the carb.

 

[jamesrxx951]

So far I have 12 flights on the 123" extra. I think I have my CG where I want it and knife edge mix set. Still trying to get snaps dialed in. I have the hardest time with that on any plane. Getting closer. In the past I got the best looking snaps with a Mej 31x12 2 blade prop but I am limited by club rules to use a 3 blade. Point rolls seem really good and spins look good also. After flying my Sukhoi I forgot how fast extras fly. Little learning curve again. As an IMAC plane I think this will fly every bit as good as the ARF IMAC king the H9 Sukhoi. If you want a great IMAC machine that is an extra I think this is a great option. It tracks great in wind. Flew in 16 mph winds yesterday and was was very easy to fly in it. I have no regrets at all buying this plane. Love it

 

[Tseres]

I knew you would like it.

 

[jamesrxx951]

For those following or even have other planes looking at baffling ideas. I think I have my combo. Straight duct to the front of the cylinders don't work that well. The right side
did ok but the left was hitting 360f. So I added a semi curved plate behind the cylinders. Much better. Both cylinders are withing a few degrees peak now. The peak was 323f. I would like to get it lower to just under or slightly over 300 but it is working. I also use triangle stock in the pipe tunnel openings to pull out air also. BTW both temp sensors are mounted in the back of the heads where air flow is likely the least.

 

[Terryscustom]

Low pressure lips to an AMAZING job of "pulling" air out of a fuse. I bet if you put a hand by a cowl inlet and blow compressed air at that lip you will feel air getting sucked into the cowl. I put two on my old PAU edge because my DA120 was getting warm in July, air was rushing in there when I tested it this way

 

[jamesrxx951]

If I didn't need to make a hole in the cowl I would have just tried the lips only. Just to see what it does. I have had great success in the past with very little cut outs. In fact a new cowl is on its way because my prop came off last night in the air. May try something small for the screw holes and test.