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Re: Rudder cables




On Fri, 8 May 1998 12:07:50 -0400 "William Wade"
<billwade@Concentric.net> writes:
>
> There are deficiencies which the factory built in, such as the canard
>bulkhead problem, and which they have chosen to do nothing about.
>It would help greatly if the factory was more open. I found out third 
>hand about how the aluminum channel NG can flex the canard bulkhead.
When 
>told about it the factory claimed it had been fixed in the new keel 
>arrangement. I certainly was never notified of the weakness.
>However, many of the techniques and experience you've gathered with 
>aluminum craft may not apply or may need to be modified. Unless you have
been
>building composite aircraft for 24 years you are not that different from
the
>rest of us in some areas.

>I witnessed the ongoing development of the retract landing gear, from
nose gear fillets >to main gear bolts to locking overcenter. An Elite
builder finds his door clearance >changes when the engine is hung. That
smacks of trial and error, not engineering. >What other problems are
lurking as planes start to age and wear? As we have 
>discussed before, Velocity does not provide sufficient instructions to
build a 
>flying aircraft. Consequently there is no proven Velocity aircraft as
such.
>Individual aircraft have logged considerable time, but they are balanced
by
>those which have crashed. I have no qualms about it as a lawn ornament.

>  Although it is not my place to instruct you, you might want to read
>AC65-12A page 239 on current return. To me that says since you no 
>longer have a conductive frame you need to figure round trip distance
when 
>sizing wire. I know you think differently, but the consequences of
oversizing 
>are less dramatic than of undersizing.  I am very conscious that I am
>self-taught. That may mean I haven't run across something yet, but it 
>also means I try hard to learn all I can.

> I am also mindful of your claim that #8 wire was sufficient for a 100A
alternator. Your >claim was based on the observation that the plane had
been flying without any >problems. I submit that there probably was not
sufficent continuous load on the >system to exceed 50A capacity. When I
asked how you arrived at that there was no
>response. It couldn't have been based on wire charts. How many builders
now
>think that's OK?

>Bill

Bill, Does your AC 65-12A page 239 take into account what to do when your
return wire in the equation may be a wire of greater size than the wire
size being calculated for? Your alternator output wire is "returned" with
a #2 or #4 gauge battery ground to the engine case. So, when sizing for
an alternator output wire, do you calculate a 30'  "round trip distance"
or 15'? (15' is the right answer!)  I don't figure the entire path since
my going to a larger gauge wire in the circuit negates the need to
calculate the entire path distance. I do need to size the larger wire
according to all of the combined loads that it may serve through its
length, though.

With regards to your specific #8 gauge wire comments. Figuring a complete
IFR avionics stack, HSI, full night capabilities, and assorted bells and
whistles, a full Velocity will draw less than 50 amps continuously. The
chart says I can draw 50 amps continuously over a 15 foot run of #8 gauge
wire, allowing for only a .5 voltage drop. Remember, by 'return' path is
my starter ground cable back to the battery.  If I were willing to accept
a 1 volt drop, I can chart out up to 80 amps continuously. I don't
recommend #8 for that situation though. I never recommend a total
combined electrical load going over 80% of the rated output of the
alternator. In any case, #8 will carry 100 amps long enough to allow even
the slowest current limiter (or fuse or circuit breaker) to protect the
wire.

If your system is a real current hog, go to a larger wire. I will stand
by my original remark though, for the average Velocity, #8 ga. wire
(while a bit undersized for over 70 amp draws continuously with 1 volt
drop allowance) is fine. My first comment would be, though, if you NEED a
100 amp alternator, go to a 24 volt system. Your current requirements are
virtually cut by 45% or more. A 60 amp capacity 24 volt system is
comparable to a 120 amp 12 volt system.

Bill, based on years of  your comments and your most recent public
comments concerning distrust and lack of faith in the aircraft, the
factory, and some of its personel, AND I quote, "I have no qualms about
it as a  lawn ornament", maybe it is time somebody suggest to you that
you consider your own words about a Velocity "as a lawn ornament". We
will all occasionally make a mistake. Maybe buying and starting to build
a Velocity was the right thing for you to do in 1991 when you got your
kit, but it seems you've gotten nothing but grief, aggrevation, maybe
even ulcers for your efforts since. I am just thinking of your good
health and long life, so give it some thought, OK? I couldn't bear the
thought of anything happening to you in, what you have so vividly
described as an aircraft with "deficiencies which the factory built in",
has not been "proven", and is not properly supported by  or engineered by
the factory. 

But hey, that is just my opinion. 

Safe and Speedy Construction!

Martin


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