Building Lasers

[Rcmaster199 at aol.com]

Ken, pattern models need that kind of accuracy, and more, there's no doubt  
about that. Bob has probably found that the lazer's accuracy of 0.1 degrees is  
adequate for flying. If wings were off compared to one another by 1/32" (0.1  
deg), I believe that you would be able to see a difference in roll. But if  
overall incidence (bothe panels compared to stab) was off by 1/32", you would  
probably trim and keep on flying.
 
The Robart incidence meter is okay as a broad reference device, but  high 
accuracy is not obtainable by this meter. It isn't made precisely  enough for our 
purposes; the variation in the plastic components is the  killer. The concept 
is not a bad one however; the blocks would need to be  machined precisely 
from block aluminum.
 
Also, consider that any scribe mark you could place anywhere on a model as  
the refernce mark to measure from, is at least about 10 thou thick. So the best 
 you could do in reality is to measure accuracy to within 10 thou or so, 
based on  your scribe marks' thickness, no matter the meter you use. 
 
For this reason, I prefer a simple height gauge with a carbide scribe  
pointer. The scriber edge is approximately 1/2 thou thick so I can dissect the  10 
thou thick reference marks I placed on my wings, stabs or fuselage. Then I am  
completely at the mercy of my  building surface. I use plate glass for  set-up 
and check it often for trueness when I am building. Believe it or not  even 
plate glass with take a set, so I rotate the surface periodically
 
regards
 
MattK
 
 
 
Honestly Bob,

 
I don't believe even the most precise fliers  could tell if their wing was 
off that little bit, or that most incedence  meters can read it that close.
Unless you are doing your building off a surface  plate, your chances of 
getting your fuse's thrust line "perfectly" level, so  as to make your incedence's 
"that" close, are very slim indeed.  They  will only be as close as the 
accuracy of your incedence meter.
I would like to have the manufacturer and part  number of the incedence meter 
that is that good, I just don't think my Robart  is that close.
 
Ken 

----- Original Message ----- 
From:  _Bob  Pastorello_ (mailto:rcaerobob at cox.net)  
To: _discussion at nsrca.org_ (mailto:discussion at nsrca.org)  
Sent: Sunday, October 24, 2004 8:35  AM
Subject: Re: Building Lasers


.1 degree is also just a shade over 1/32"  difference EACH at the leading and 
trailing edges.  Understand  that we need those kind of accuracies for best, 
but I believe most folks do  NOT resolve incidence to 1/32"....but I 
understand the need to state  precisely.

Bob Pastorello
_rcaerobob at cox.net_ (mailto:rcaerobob at cox.net) 
_www.rcaerobats.net_ (http://www.rcaerobats.net/) 
 
 

----- Original Message ----- 
From:  _Karl G. Mueller_ (mailto:kgamueller at rogers.com)  
To: _discussion at nsrca.org_ (mailto:discussion at nsrca.org)  
Sent: Saturday, October 23, 2004  10:06 PM
Subject: Re: Building Lasers


Bob,
 
A tolerance of .1degrees is not very close to set  the incidence.
Over a wing root of 20" it works out to be .035 inch.  This is the max.
positive incidence I use on the wing when setting  up a pattern plane 
with the stab being set to zero.  A  .1 degree tolerance could give me 
a setting between 0 and .070  positive when setting up a wing with 
a 20" root.
 
Karl G. Mueller
_kgamueller at rogers.com_ (mailto:kgamueller at rogers.com) 



----- Original Message ----- 
From:  _Bob  Pastorello_ (mailto:rcaerobob at cox.net)  
To: _discussion at nsrca.org_ (mailto:discussion at nsrca.org)  
Sent: Saturday, October 23, 2004  9:23 PM
Subject: Re: Building Lasers


The purpose of the ones I have is not to  check incidence, but to verify 
alignment "square", and  "parallel"...currently, a lot of folks use different 
methods, some  height gauges, some fixtures.  When building a plane, I have always 
 struggled with getting the stab square to the fin, and then the wing  
parallel to the stab...and these differences sure do make a difference  in how a 
bird trims out.
 
Incidence is checked with our electronic  digital levels, at .1 degree 
accuracy :-)

Bob Pastorello
_rcaerobob at cox.net_ (mailto:rcaerobob at cox.net) 
_www.rcaerobats.net_ (http://www.rcaerobats.net/) 






 
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