KR> Re: Tri gear tail first on runway.

[mbz...@comcast.net]

I don't have a dog in this fight, but that is the way I also understand the 
stall. Angle of attack is the angle of the chord relative to the wind, not a 
horizontal line. So if the plane is descending in still air, the angle of 
attack will be greater than the attitude of the wing chord. 

. 
List-Post: krnet@list.krnet.org
Date: Wed, 6 Apr 2011 20:23:23 -0500 
From: "Mark"  
Subject: RE: KR> Re: Tri gear tail first on runway. 
To: "'KRnet'" ,  
Message-ID: 

 

Content-Type: text/plain; charset="iso-8859-1" 

The angle of attack is dependent on the 'relative wind' and has nothing to 
do with the wing chord reference to speed, attitude of the aircraft/airframe 
or anything else other than the relationship of the aerodynamic chord of the 
wing relative to the "relative wind". There are a number of publications, 
including FAA stuff, that explain the concepts (I bet Mark L can chime in 
here too) :) 

Mark W. 
N952MW 

KR> RE: Wheel Pants Landing Lights

[mbz...@comcast.net]

If you suspect the maintenance might be an issue, than maybe a simple circuit 
with a LED on the instrument panel might be interesting. Circuit can be 
designed to light up when a bulb is out and can be active even if the lights 
are not powered on (ie: day time) That might save some cycles on the 
switch/relays and bulbs, extending their life. total weight should be no more 
than the weight of a led, a resistor and a transistor. 


""I fully expect the lights in the pants to be a maintenance "issue", but 
it is a checklist item that I am willing to deal with."" 

KR> Wheel Pants Landing Lights

[mbz...@comcast.net]

Is it customary to leave wheel pants on in the winter months on a KR? I really 
don't know, so I'm asking. Seems that at my airport wheel pants are removed on 
all aircraft in the winter. And I would imagine that the lights would go 
through abuse they were not designed for. Seems that every time I drop a flash 
light, the bulb is gone. But than again, I have absolutely no experience with 
such things, just thinking out loud. 

""Hi Dave, 

The person, I'm getting my KR2 project from went the same route, though I 
would really like to hear everyones opinion on this"" 

KR> Exhaust headres

[mbz...@comcast.net]

Among all the distractions, I hope no one minds that i get a bit of topic and 
start talking about aircraft conversions 
I was wondering why so far I did not see any headers on corvair engines. 
On cars, headers accounted for up to 5% increase in horse power. What is the 
reason 
why the same can not be true for aircraft conversions? I guess at cruise the 
exhaust gases are efficiently 
evacuated and maybe headers will not give much of an increase in hp. But still 
I think it would be a benefit 
for the weight at take-off and climb. And also would increase the smoothness of 
the engine. 
Looking at the exhaust examples, I wonder if the exhaust really is tuned for 
the engine, or can the back-pressure 
be smoothed out. 

KR> Re: tubular wing tanks

[mbz...@comcast.net]

in my experience PVC is not a good male mold. Hard to separate. Cardboard 
shipping tubes on the other hand are perfect. Once Composite sets, a few minute 
soak in a bath tub, and the tube separates and peals off. 

"Forgive me if this is an ignorant idea, but has anyone considered laying up 
fiberglass tube tanks using PVC pipe as a male mold? 

Edward Spyker" 

KR> fuel burn vs Hp

[mbz...@comcast.net]

You guys might be over thinking this. 

In theory that calculation is possible if. 

You have perfect carburation (but you don't) 
you have perfect timing (but you don't) 
Your manifolds are 100% efficient (but they aren't) 
your fuel burn is based on top output at stp (but it isn't, its an average) 

and so on. If we think about it, we can add at least 50 more things that will 
affect your fuel/hp ratio. 

but if your setup was perfect than 2gph for 100hp is closer. 

KR> Latest intake manifold experiment

[mbz...@comcast.net]

In my younger days we used to put aluminum window screening sandwiched between 
2 carburetor spacers to help atomize fuel. Theory was that the screen creates 
micro vortexes and helps with a more even air/fuel mixture distribution to all 
cylinders. We didn't have a dino machine to test this out, but my guess would 
be that we gained at least 5hp. 
This might be worth looking into for the uneven burn problems. 

KR> RE: KR nose wheel shimmy

[mbz...@comcast.net]

Like you, I have my experience with cars. I would like to know how negative the 
caster angle was on the plane. 
Yes, unlike in cars where the caster angle is positive, and the more positive 
it is, the better stability, and wheel return. 
But its harder to turn the wheel. 
In the nose wheel of a plane, the caster angle is negative, very much like in a 
shoping cart. But similar principles apply. 
Stability should improve with a more negative angle, and wheel return to center 
should be better 
but it should be harder to turn. 
In a shopping cart, when the wheel doesn't have a full load, it will also 
shimmy. Im also curious 
if the weight of the plane in motion is evenly distributed to all wheels, or is 
the weight on the nose wheel light. 
and if the air pressure in the tire was adjusted to compensate for a lighter 
load. 
IMHO most common causes for a shimmy like that would be an over inflated tire, 
a tire out of round, or an unbalanced tire. 
Also there is a posibility that the wheel was modded in a way that the caster 
angle was decreased, (moved closer to 0) 
If everything checks out, Im betting on an over-inflated tire same can be 
observed in a car when the tires are over-inflated 
going over a bump, the tire will bounce, and steering wheel will oscilate. 
I do agree that the wheel pants could amplify the oscilation. In the past open 
wheel race cars suffered from catastrophic 
crashes due to aerodynamics on the open wheel. 
I really dont know anything about airplane landing gear, but am comparing the 
sympthoms to automotive tech. I do admit, 
no where on a car or a bike is the wheel caster negative so its hard to compare 
the two. 



"Maybe I should have emphasized caster angle a little more... caster angle 
(the angle from the vertical pivot point to the contact patch of the tire on 
the pavement, similar to the trail on a motorcycle) can improve the 
stability and natural tendency of the tire to track true. I agree with all 
of the points that Mark L has made, but the video I saw showed the shimmy 
continuing all the way down the runway... if the caster angle and balance 
had been properly done, the shimmy would tend to cancel out as the plane 
went down the runway. Granted, I know more about motorcycles and cars than I 
do about planes, but once the bird is on the ground, I would think similar 
rules would apply. Yes damping is important, but if the geometry of the 
set-up is off, it won't help the shimmy unless the gear is "locked in" (too 
stiff) which kind of defeats the purpose of a castering nose wheel doesn't 
it?"

KR> Battery crossover (isolator)

[mbz...@comcast.net]

I think you might have misunderstood me. I was talking about a crossover, or 
more commonly known as an isolator. 

There wouldn't be any mods to the dashboard. All an isolator does is isolates 
the batteries, so they are not "bank" 

charged. Just do a search on a battery isolator, and you will get many hits. It 
connects to the alternator (+) and from there 

goes to the batteries. Here is a link to the first of many hits. But I'm sure 
you can find much cheaper sources 
http://www.newmarpower.com/Battery_Isolator_Integrators/Battery_Isolator_Integrators.html
 

Also might look at the intergrator just below the isolator, its a different 
option, that does something similar. 

This was in response to your concern of one battery going dead, and dragging 
the other with it. 


"I'm not ready for 
a major panel redesign yet, probably never.  With all the additions and 
changes over the years it could well do with a panel makeover"

KR> Back-up Battery

[mbz...@comcast.net]

I'm not sure if this would work in a plane as a back-up. But in RVs and boats 
in order to use 2 different batteries 
for instance a car battery and a deep cycle battery, A simple cross-over 
circuit is used that can be purchased 
at any RV or marine store. The cross-over is pretty much just a high current 
rectifier bridge that allows current to 
travel only in one direction. 

"In designing my back-up system I took care to completely isolate both 
systems . . . except for the occasions when I might want to connect them 
. . . which would be to charge them concurrently, either in the hanger or 
in flight." 

KR> Wide Band 02 Controller with Gauge

[mbz...@comcast.net]

Not to confuse anyone, but This gauge seems to be pretty sweet too. 

http://www.holley.com/534-201.asp 

KR> experimenter Polyisocyanurate Foam

[mbz...@comcast.net]

You might want to double check the Tuff-R 



I think it has an aluminum laminate on both sides 



I'm not sure, but if thats true, the laminate IMHO makes the foam useless 



for construction. Also I'm not sure if the properties of the foam are with or 
with out 



the aluminum laminate. So if you peel the laminate away, the properties 



might go down the hill.