i found that there was a piece of metal riveted into the duct to stop water blowing straight through(at least this is what i think its for) i found that in the closed position it was against the firewall and in the open position it was against this strip of metal so it didnt flow air either way. what i did was change where it was hinged from( changed from top to the bottom of the duct). works much better. not sure if the bend in your case is to fit around some body work or as you say direct air against it to stop it fluttering. mine does not seem to flutter yet cheers ric ________________________________ From: [email protected] <[email protected]> on behalf of Ian Mc Phee <[email protected]> Sent: Wednesday, October 6, 2021 6:02 AM To: DOG LIST <[email protected]> Subject: Re: [DOG mailing list] Cabin Air NACA duct
Sorry I am away from dimona so no photos but I fitted either side of cockpit two NACA inlets with a ball vent which opens and closes. I copied what the HK36 has. I found the one on top of cowl was limited for air for ventilation and that flap is not reliable. I guess it can supply air to canopy but from memory the hk36 has no air going onto canopy. This on top h36 is a poorly shapped NACA in my opinion. I believe 1. the shape of NACA is critical with little nick near wide part. 2. A sharp edge on the NACA upper serface 3. A wing section on the right angle end of NACA on inside and this sucks air in to cabin. 4 is the angle of ramp but its is less critical I believe. 5 the alignment we ith airflow is moderately important (I put thick black string where they were going and had it photographed on landing so I had the air flow line) A friend did his thesis year on NACA air intakes and explained it one wet no flying day. Ian Mcphee +61 428847642 On Wed, 6 Oct 2021, 11:15 Tom Preisser <[email protected]<mailto:[email protected]>> wrote: I am not clear what you mean, Ian. Tell me more please. On Tue, Oct 5, 2021, 19:51 Ian Mc Phee <[email protected]<mailto:[email protected]>> wrote: I gave up on it and fitted 2 side NACA ducts as per HK36. I think that flap is opposite to what you think. Ian McPhee +61 428847642 On Wed, 6 Oct. 2021, 05:46 Tom Preisser, <[email protected]<mailto:[email protected]>> wrote: Gentlemen, For many years now I have wondered why someone ( Factory ? Thais ? ) bent the bottom of the flap that shuts off air through the fresh air louvres and canopy demister vents. I have assumed that it fluttered in the open position, and the bend was to prevent this from happening. However, with this bend it will no longer completely seal the incoming air ( or rain ) entirely, nor will it allow an unobstructed flow of fresh air through the duct when open ( due to interference with the screen ). Were I to straighten the bend to obtain a flat flap, I would not be able to open the flap fully. What do yours look like? Cheers, Tom. --------------------------------------------------------------------- You are subscribed to the Dimona Owners Group mailing list. This list is archived in public. http://waikeriegliding.com/dog/ To unsubscribe, send email to: [email protected]<mailto:[email protected]>
