Message-ID: <19981020220411.16597.qmail@www06.netaddress.usa.net>
Date: Tue, 20 Oct 1998 22:04:11
From: Dan Schaefer <dfschaefer@usa.net>
To: lancair.list@olsusa.com
Subject: cowl vents, tank vents, capacitance gauges
Mime-Version: 1.0

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To Scott K. - could you be a little more specific regarding the "off
center funnel" duct, please? Sounds interesting but I can't picture
the things. Once I retire from Bomber are Us (soon, very soon!) I'm
planning to install a 320 style cowl on N235SP and will probably want
to re-do my oil cooler ducting. I want to look at anything that 
someone has found to work well and it sounds like those automotive
ducts do that.
(I'm going to do the cowl upgrade because I'm sure I'm giving up too
much to cooling drag since my CHT's are running quite low at all
times - probably due to the wrap-around cylinder air dams I built
for this installation.)

Those drop-down cowl vents are a nice idea and I've seen a number of 
Lancairs here in Southern Calif. that have them. If people don't have 
them installed, you will see oil access doors standing open, on just 
arrived Lancairs, at the local $100 hamburger joint. My only 
reservation about the ones that just drop down when you stop is that
they're always open on the ground. Probably no big deal, but if I'm
going to park outside somewhere for a while, I like to close off the
engine compartment as best I can - I've had a complete nest with a 
clutch of eggs deposited on an engine once, in just one week. When I
build my new cowl, I'll put in the vents, but I think I'll also steal
another of Tony Bingeles' ideas and actuate them with a VW carb heat
thermal bellows. These are small lightweight linear actuators that
the air-cooled VW bugs (and 356 Porsches) used to actuate a flapper-
valve to turn on/off hot air directed over the carburetor(s) as the
engine cools off/warms up. Will open the vents when hot and close 
them when things cool off without attention from the pilot.

Matt Hapgood - ask Ray Modert about how accurate those capacitance 
gauges are. Seems I remember him grumbling about them some time back. 
Ray has a business in Ventura, CA (bus. ph. 805-983-1145). If you do
give him a call, be advised that he runs a one-man shop so don't 
tie him up too long. Ray has a very pretty Lancair that started life
as a 235 but grew up to a fire-breathing LyCon 220 HP rocket. Only guy
I ever knew who had a $1000 set of gold leaf stripes on his plane.

Be careful of the two wing tanks tee'd together. Take a clue from FAA
certified machines: (let's face it, a lot of the stuff they insist
upon is the result of many hard earned lessons) For the reasons put 
forth by many who sent posts in the last week or so, you can find fuel
selectors in high wingers that have the positions R, L & Both - in
contrast, invariably on low wing aircraft it will be R, L & Off. 
Why reinvent the wheel? A valve in place of the Tee will keep your
pumps from sucking air sometime when you can least afford it and it 
really is nice to be able to balance the useage from the wing tanks.

Hey John, you're not going to damage your header by overfilling, the
vent line will not let that happen. If you don't do something about
it you will pump fuel overboard and if you pump it all out, you might
damage the header because you ran out of fuel, but not from over-
pressure. If you don't have a vent, you can't feed the engine for
long anyway, so by definition, you've got to have a vent. (Unless 
you've got a bug that got itself stuck in there - and you need to 
take care of even that eventuality, too).

Marv, venting to the active tank has been done and you're correct, a 
second valve that can be slaved to the main selector valve is 
required. I don't like the idea because, as you no doubt can tell 
from my railings here, I believe that unnecessary complexity is a bad
thing. In this case, it adds an extraneous gizmo that does more to 
add weight than utility. (I'm a firm believer in something attributed 
to Burt Rutan when asked if some item was too heavy to use in an 
airplane someone was building. Burt was said to have answered, "Throw
it up in the air and if it comes down, it's too heavy"! These things
gain weight just sitting in the hangar so there's no need to go about
it actively, and I can tell you for sure (as I very often fly a good
friend in the right-seat who weighs in at around 210 lbs) lighter is 
MUCH better!!!

Interesting, I guess no one has done anything about reflexing the
ailerons (actively or on paper) or I'm sure I would have read a post
about it by now. It still intrigues me and I'm going to work on a 
method to do it, at least the mechanics of it. I would like to hear
from any one of you who are aerodynamics types and who might have 
given the subject some thought. It just seems logical that the 
pitching moment of the Lancair wing doesn't stop at the outboard ends
of the flaps - and if reflexing the flap section of the wing allows
the airplane to go faster than when not reflexed, reflexing the 
remaining 30% or so should allow the airplane to be even faster.

Cheers,

Dan Schaefer
N235SP


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