REFLECTOR: Rain and top fuselage naca

Tue Oct 11 10:25:22 CDT 2011

Thanks John
That was a wealth of information
and greatly appreciated.
I'll be sure to check on those holes
Would hate to find an aircraft full of water :-)

Thanks again for all your help and knowledge.

Kevin Baker

.

On Oct 11, 2011, at 9:55, "John Abraham" <john at velocityaircraft.com> wrote:

> Kevin,
> 
> There should be a drain going out the bottom of the aircraft that connects
> to the fresh air NACA on the top of the fuselage so that water can get out
> while sitting on the ground or in flight.  The two large NACA's will allow
> water to enter down the engine compartment.  You should have a 1/4" drain
> hole at the low point of the bottom cowling up against the flange and
> firewall.  To prevent water from entering the cabin you need to do several
> things.  First, in the engine compartment you need to make sure that your
> wire ducts on the bottom of the fuselage and sealed with an expansion foam
> so that the water cannot enter the duct.  Otherwise you will end up with a
> floor of water in the aircraft.  The water will also enter the cowling exit
> while sitting on the ramp even with the cover on it.  Secondly, you need to
> seal the canard cover with either 3M tape or silicone to prevent water from
> entering the front.  Thirdly, the elevator torque tubes can let some water
> in as it runs down the side of the fuselage.  You can use orange silicone
> baffling material to make a seal.  This also will help in colder weather to
> seal the cabin.
> 
> If you have a fresh air vent in the front of the fuselage on the co-pilot
> side of the nose, this can also let water in while flying.
> 
> Since this can be an issue for the aircraft, it is suggested to drill a 1/4"
> hole on the floor of the aircraft just in front of the rear seats.  This is
> about the low point of the aircraft and will allow any water to drain if it
> gets inside of your aircraft.  Don't forget to also drill a 1/8" hole in
> your strake pockets that the door closes off as well as your winglet
> bottoms.
> 
> Best,
> 
> John
> 
> -----Original Message-----
> From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
> Behalf Of Scott Derrick
> Sent: Tuesday, October 11, 2011 10:07 AM
> To: Velocity Aircraft Owners and Builders list
> Subject: Re: REFLECTOR: Rain and top fuselage naca
> 
> Kevin,
> 
> I only have two large NACA's that connect to the engine plenum.  I don't
> know about a small third scoop.  I've seen pictures of it but don't know
> what its for.
> 
> Scott
> 
> -------- Original Message --------
> Subject: Re: REFLECTOR: Rain and top fuselage naca
> From: Kevin Baker <flykb at verizon.net>
> To: Velocity Aircraft Owners and Builders list <reflector at tvbf.org>
> Date: 10/10/2011 06:49 PM
> 
>> Thanks Scott
>> What about the small naca scoop that goes into the cabin?
>> Did water drain into the cabin or fill up the back of the channel.
>> ??
>> 
>> Thanks
>> Kevin
>> 
>> .
>> 
>> On Oct 10, 2011, at 19:33, Scott Derrick<scott at tnstaafl.net>  wrote:
>> 
>>> Sitting or flying the rain enters the plenum and drains down through the
> engine.
>>> 
>>> In flight I imagine some of the water exits out the rear openings.
>>> 
>>> I do have multiple drain holes in the lower cowling at the low points and
> a drain hole in the ram scoop/filter housing which is below the
> fuselage/rear cowling.
>>> 
>>> Interesting story about not having a drain hole in a low mounted intake
> scoop.  I was washing my plane last summer.  It was about 6pm and the
> airport was deserted. Finished washing and wiped it down with a shammey, got
> in and was going to taxi it back to the hanger. I was pretty aggressive in
> spraying it down with water and rinsing as it was really filthy.
>>> 
>>> I gave it a 3+(probably 5 I was distracted) second burst on the fuel pump
> for priming and hit the starter. It coughed but didn't start?   I gave it
> another shot and hit the starter, it made an odd muffled kind of sound and
> didn't start?  Hmmm... Not like it at all.  I bent out the door and down to
> look back and under saw a fluid dripping from the drain holes in the cowl
> which seemed OK, I had just sprayed it with water.
>>> 
>>> I gave it another short burst of fuel and hit the starter, still nothing.
>>> 
>>> Got out and walked back to the rear and bent down to see if that was
> water slowley dripping from a drain hole, I rested my hand on the intake ram
> scoop below the fuselage. IT WAS REALLY HOT!
>>> 
>>> I thought, SHIT THATS HOT! I touched it again to convince my unbelieving
> self that it really was hot, IT WAS!
>>> 
>>> I ran back to the front and opened the throttle, idle cutoff on mixture
> and held the starter on for about 30 seconds.  It actually coughed a few
> times at about the 15 second mark and seemed like it wanted to start.
>>> 
>>> I ran back to the rear and the intake was a bit cooler.  In a minute it
> was definitely cooling off. I removed the rear part of the scoop and it was
> partially black in side as was the servo intake tube. The filter in the
> front part of the scoop was partially melted. NOthing damaged but the filter
> thank god.
>>> 
>>> Without a drain hole the rear part of the scoop filled up with I don't
> know how much water, then when I gave it a shot of fuel(probably too much)
> some ran down and probably floated on top of the water.  That fuel ignited
> somehow, maybe a back fire!
>>> 
>>> I now have a 3/16 drain hole in the lower part of the scoop. I had not
> put one in because I was trying to seal it really tight for ram pressure in
> flight and sucking dust during taxi.  Now I sacrifice a minute amount of
> pressure during flight and probably don't get but a few specks of dust
> through that little hole during taxi...
>>> 
>>> live and learn..
>>> 
>>> Scott
>>> -------- Original Message --------
>>> Subject: REFLECTOR: Rain and top fuselage naca
>>> From: Kevin Baker<flykb at verizon.net>
>>> To: Velocity Aircraft Owners and Builders list<reflector at tvbf.org>
>>> Date: 10/10/2011 04:55 PM
>>> 
>>>> Hi all
>>>> As it's raining here in Dallas, finally.
>>>> I was wondering about the naca scoops on top of the fuselage and
> rain/water getting into them.
>>>> More importantly the small center air scoop.
>>>> Are folks putting in water drains for rain or wash water to drain from?
> Or ?
>>>> 
>>>> Thanks
>>>> Kevin Baker
>>>> 
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