Web-Slinger LIVES!!!!

[Jerry Schneider]

Thanks Hat.

 

Yesterday, Buly and Doris Alieve stopped by my hangar on their way to a cookout 100 miles north of me. (1 hour and 6 minutes from Ft. La-de-da to Tampa... Gotta love these planes!)

After taking the plane up for a short exibition flight for them, (They said they didn't really belive it could fly. ), I cut the down-draft plenums out to re-make them in an effort to improve cooling. I should be back in the air in a week! I live 28 miles from the airport, so I don't get to fly or work on it as often as I like.

 

5 hours on the Hobbs and counting.......

[Kent Ashton]

Jerry, Rather than rebuild those ducts (if you still want downdraft cooling), How about p-51 type of scoop on the top of the turtleback or cowl? It would a simple straight-forward way to get air into your plenum. No doubt, a top-side scoop would show a lot less cooling drag due to less skin friction drag than inside the ducts, fewer direction changes in the flow. The opening could be small. It would be fairly easy to remove and rebuild if necessary.

 

I'm sure you've seen the top-side NACA used on the Velocity's but I think there is more luck and magic in getting a NACA to work right on the back side of the fuselage curvature.

 

Curious what kind of cooling you were seeing with what you had.

[Jerry Schneider]

Jerry, Rather than rebuild those ducts (if you still want downdraft cooling), How about p-51 type of scoop on the top of the turtleback or cowl? It would a simple straight-forward way to get air into your plenum. No doubt, a top-side scoop would show a lot less cooling drag due to less skin friction drag than inside the ducts, fewer direction changes in the flow. The opening could be small. It would be fairly easy to remove and rebuild if necessary.

The ripple effect would be pretty bad. I'd have to rework the engine intake, the oil cooler, and who knows what else. The ripple effect is BAD JUJU! I also feel the present plan gives a much cleaner appearance. I would hate to waste the drag created by the Plans NACA,(That's easy, close it off. Did I mention ripple?). Plus, another Cozy driver with DDC (and great cooling #'s) gave me some advice on what was wrong with my work. Hopefully, this attempt will be better.

 

Curious what kind of cooling you were seeing with what you had.

Avg. EGT 425 degrees in cruise. Not out of spec, but I think I can do better with some cleaner work.

[Lynn Erickson]

The ripple effect would be pretty bad. I'd have to rework the engine intake, the oil cooler, and who knows what else. The ripple effect is BAD JUJU! I also feel the present plan gives a much cleaner appearance. I would hate to waste the drag created by the Plans NACA,(That's easy, close it off. Did I mention ripple?). Plus, another Cozy driver with DDC (and great cooling #'s) gave me some advice on what was wrong with my work. Hopefully, this attempt will be better.

 

Avg. EGT 425 degrees in cruise. Not out of spec, but I think I can do better with some cleaner work.

We know you meant CHT. keep at Jerry I know you will get it sorted out.

[Jerry Schneider]

We know you meant CHT. keep at Jerry I know you will get it sorted out.

DOH!!!! ......

[Drew Swenson]

425 is too hot for normal operation---regardless of what the book says. Need to be below 400---375 is better. If I run ROP, I will be in the 375 range---if I run LOP, I will be at 325 to 350----and at the same speed.

 

What is your total area on the intakes?

[Jerry Schneider]

425 is too hot for normal operation---regardless of what the book says. Need to be below 400---375 is better.

Hence my desire to re-work.

What is your total area on the intakes?

Between 65-70% of the NACA. The rest goes to the oil cooler and engine intake.

[longez360]

I designed my system to operate at temps per the Lycoming service bulletin. That's how you should operate your engine. Forget old wives tales about CHTs and oil temps... Per the old Lycoming Service bulletin and Skyranch you are actually OK. Lycmong now states you should be below 400F.

 

I consulted the Sky Ranch Engineering book and checked the Lycoming website for details... Seems the Lycoming service bulletin quotes maximum service life temps CHT<400F and Oil 165-220F in cruise, and observe redline in climb. The Sky Ranch Engineering book and previous Lycoming service bulletins show CHT requirements 350F-435F, the average of which is 392.5F. If I average their oil value, I get 192.5F. . . That's almost exactly what I get on VH-WEZ at OAT=82F in high power cruise. I can control my oil temp using a variable outlet which allows me to reach 212F if I like (nice to have).

 

Forget inlet size. Be honest with yourself about your baffles, if they aren't sealed tight, and I mean TIGHT, you are wasting your time. If you have antennas in the inlet, remove them. If you have a NACA submerged duct on the belly and your nose puck is not faired, fair it. The feet that come with electric retract units have an effect on NACA ducts also. Aside from that, work on inlet diffusion, and exit size (remove your spinner and flight test). Remove anything that hinders airflow through your cylinders - hoses etc.