ORIGINAL: f3a05
Two questions:
Does anyone have drawings,or a source for the design, of NACA ducts?
I'm told that the ramp(s) are important.
Also, on the BM, I presume they're for lower crankcase cooling? The entries look a little far back don't they?
The ducts were designed to provide extra cooling for the batteries on the electric versions. They work VERY well.
I liked them so much I put them on my glow planes. Not necessarily to cool the crank case. They are optional, but come with the kit.
The source of the design? 1985 Chevrolet Z-28 Camaro hood. LOL it ain't rocket science on these.
Somebody mentioned to me that they might be messing with my airflow for cooling once, so I blocked them off; made no difference really. But on the electric, we ran up the motor and checked the airflow over the batteries with and without the Naca ducts. Just a guess by feel, but it they increase airflow by 30% or so. You can really feel a difference.
Rudder question: No the rudder is about the same, you just add a piece of 1/4" as the tail post of the fin, which increases the chord of the whole thing by 1/4".
-Mike