Ram air to alternator

Guys,
I replaced my over size cowl rubbing weak output tractor alternator with a Plane Power set up from Vans - NICE! I have a 1" scat tube hanging down from the cowl inlet. What is the best way to "direct this ram air to the rear of the Plane Power alternator" as the directions suggest. The old alternator had a shield and a 1" tube to hook to, the Plane Power alt. does not....THANKS

I am also very interested in answers here. The one thing I can add is that it would be all too easy to blow water at the alternator unless precautions to prevent this are included in the installation. Perhaps a simple trap can be formed in the scat tube run to keep the water from getting through, and perhaps a small hole so the water can drain out?

Randy C

I used a piece of 1/4" copper tubing. Tie-wrap it to the SCAT ducting and bend the tubing to the configuration you want. It's short enough that you only need to secure the SCAT at the inlet flange on the baffle.

Is it really required??

I'm finishing up my baffle ramps and have nopt made provisions to run a blast tube to the alternator (Plane Power) . . . it this imperative??

zip tie to alternator bracket

I zip tied the bottom end of the scat tube to the bracket of my ND alternator.

Its my understanding that the rear bearing area needs to be cooled and not the field windings and brushes.

Is it needed?

...I understood that the ram air was needed because the refurbished car alternators originally supplied by Van's ran backwards and their cooling fan didn't work. The Plane Power's have an effective fan and don't need ram air. At least that was the rumor????
Jim Sharkey

They will probably work fine indefinitely without it, but cooled they could work indefinitely+. I know some of the certified installations don't have blast tubes (for the Plane Power).

Like other builders, I simply ran a short length of 1" scat to the rear of the alternator and secured it with zip ties. It is an open question or judgment call....take your pick....whether the 60 Amp Plane Power alternator installed here and required to put out a max of maybe 30-40 amps with everything in the airplane switched on, yet routinely be asked to put out a fraction of that load really needs an additional blast of cooling air. We may well hear differing opinions on this and a whole host of other subjects but in the end it is always up to the builder (and his dime) to make such calls.

I used the little black corrugated plastic tube that comes with the FWF kit from Van's. To secure this wobbly little guy, I tie-wrapped a piece of 12 awg solid copper electrical wire (insulated) to the blast tube every inch. I bent a 'U' in each end of the wire so it won't slide out and then I could bend the blast tube any way I wanted. The wire made the blast tube stiff and it stays where you bend it. I did the same on two blast tubes at the aft baffle for cooling the mag and also the mechanical fuel pump. I just checked my picture file and I don't have a picture that shows it, but it's simple. Leave the wire a little short on the end that goes through the baffle and use a little RTV around the blast tub/baffle interface to hold it there.

Scott
RV-8 Fastback