Van Vleet Cowling Mod in Q-Talk 119


David Richardson
 

Hi Guys,

I'm curious about the modification Richard made to his Turbo Q2 and
just why he is seeing such an improvement. It looks simple enough to
do and with my Tri-Q2, opening up that area would make removing the
lower cowling much easier. I wouldn't mind getting rid of the cowl
flap either.

Is the idea sound enough to be worth hacking up my cowling?

Thanks,

Dave Richardson
Tri-Q2 825DR


Sam Kittle
 

Dave,

Since many of the original kits were upgraded to Q-200's, I think it would
not be hard to find an available cowling on this list.

Sam

-----Original Message-----
From: Q-LIST@... [mailto:Q-LIST@...] On Behalf Of
darichardson75
Sent: Saturday, November 04, 2006 6:54 PM
To: Q-LIST@...
Subject: [Q-LIST] Van Vleet Cowling Mod in Q-Talk 119

Hi Guys,

I'm curious about the modification Richard made to his Turbo Q2 and just why
he is seeing such an improvement. It looks simple enough to do and with my
Tri-Q2, opening up that area would make removing the lower cowling much
easier. I wouldn't mind getting rid of the cowl flap either.

Is the idea sound enough to be worth hacking up my cowling?

Thanks,

Dave Richardson
Tri-Q2 825DR




Quickie Builders Association WEB site
http://www.quickiebuilders.org


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Rene Robertson <q2robertson@...>
 

Hi Dave,
I believe Richard is onto something. I did away with my cowl flap and built an extactor type exit as can be seen in my article in issue 117. I didn't see any speed increase but did notice a substantial cylinder head temp drop. Cruise CHT is now 225 and sustained climb out never goes over 300.
If I was modifying my cowl over again I would incoporate Richards cowl bottom opening. I believe his numbers are correct.
If the heads run cooler great. If you get a performance increase to boot, even better.
Rene
Q2 C-FBWV

----- Original Message ----
From: darichardson75 <darichardson75@...>
To: Q-LIST@...
Sent: Saturday, November 4, 2006 6:54:02 PM
Subject: [Q-LIST] Van Vleet Cowling Mod in Q-Talk 119

Hi Guys,

I'm curious about the modification Richard made to his Turbo Q2 and
just why he is seeing such an improvement. It looks simple enough to
do and with my Tri-Q2, opening up that area would make removing the
lower cowling much easier. I wouldn't mind getting rid of the cowl
flap either.

Is the idea sound enough to be worth hacking up my cowling?

Thanks,

Dave Richardson
Tri-Q2 825DR


Dave Richardson <dave@...>
 

Let me ask this in another way.



The little ridge/lip seems like it would create ripples or otherwise
disturb the air below the cowling.



Does that effectively lower the pressure under there or something to aid
in the cooling process?



What effect would the half football shape and the tapering lip have on
the air?



Thanks,



Dave Richardson





_____

From: darichardson75 [mailto:darichardson75@...]
Sent: Saturday, November 04, 2006 9:54 PM
To: Q-LIST@...
Subject: [Q-LIST] Van Vleet Cowling Mod in Q-Talk 119



Hi Guys,

I'm curious about the modification Richard made to his Turbo Q2 and
just why he is seeing such an improvement. It looks simple enough to
do and with my Tri-Q2, opening up that area would make removing the
lower cowling much easier. I wouldn't mind getting rid of the cowl
flap either.

Is the idea sound enough to be worth hacking up my cowling?

Thanks,

Dave Richardson
Tri-Q2 825DR


MartinErni@...
 

Dave,
This technique definitely works. I have used it in the past with good
results. There are 2 problems that you should be aware of though. The lip
creates a large low pressure area and you don't want a fuel vent anywhere near it
(measured in feet, not inches - experience). It creates a lot of drag.
Earnest


Larry Severson
 

The little ridge/lip seems like it would create ripples or otherwise
disturb the air below the cowling.
yes, diverts it downward.



Does that effectively lower the pressure under there or something to aid
in the cooling process?
Creates a low pressure area sucking the cowl air out.


What effect would the half football shape and the tapering lip have on
the air?
see above

Larry Severson
Fountain Valley, CA 92708
(714) 968-9852
larry2@...


MartinErni@...
 

Yes Dave, size matters. :-) I started with about an 1.25 inches and kept
trimming to get the right temps. I don't remember exactly but I think I ended
up with about .75 on the O200. I have a completely different inlet and
outlet now and don't us a lip.
Earnest


MartinErni@...
 

Dave,
I had problems with the vent in the same position you describe and had
to move it outside the edge of the fuselage. It is really scary when your
engine will only run in a nose high position. At high speeds the engine wants to
quit.
Earnest


Dave Richardson <dave@...>
 

Thanks, Earnest.



Welcome back!



Do you think reducing the height of the lip would reduce the effect?
Richard's lip was .75" in the front and tapers down to .50" in the back.
How does that compare with the size you used? Could this be sized to the
larger Cessna engines he referenced and needs scaling down for our
smaller engines and cleaner airframe?



My fuel vent is between the fuel tank and the aft surface of the canard
and it drops about 3-4" below the bottom of the fuselage on the
passenger side. Is that too close?



Thanks,



Dave



_____

From: MartinErni@... [mailto:MartinErni@...]
Sent: Monday, November 13, 2006 3:50 PM
To: Q-LIST@...
Subject: Re: [Q-LIST] Van Vleet Cowling Mod in Q-Talk 119



Dave,
This technique definitely works. I have used it in the past with good
results. There are 2 problems that you should be aware of though. The
lip
creates a large low pressure area and you don't want a fuel vent
anywhere near it
(measured in feet, not inches - experience). It creates a lot of drag.
Earnest


Pat Panzera <panzera@...>
 

Speaking of Van Vleet, I ran across him this weekend and made him promise to
join us at Jean and Livermore next year.

Pat