REFLECTOR: Elevator Trim Spring

[Chuck Jensen]

Scott,
You wrote that "I think it would be hard enough trying to fly it with an
inoperative trim  system as it is, any stiffer and I'd be out of muscle
pretty fast."  If I understand the issue here (and that is not a given),
the installation of a stiffer trim spring would assist you, not create
additional resistance that you would have to overcome, in other words,
the stiffer spring would be a force-multiplier for you.

Then, instead of using your muscles to compensate for the trim spring,
you can use them for important things like tuning your Sirius radio.

Chuck Jensen


-----Original Message-----
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of Scott Derrick
Sent: Wednesday, February 01, 2006 10:08 AM
To: Velocity Aircraft Owners and Builders list
Subject: Re: REFLECTOR: Elevator Trim Spring

I can see how he might need more travel.

As my trim is set up, I have just enough down trim to cruise at 65% 
power with just me in the front. If its bumpy I don't have enough, I 
have to constantly give it a shove forward  or use George. If have two 
in the front I don't have enough up trim for a hands off 90 knot 
approach, just me its fine.    If I fix it so I can fly a 90 knot 
approach hands off with two, I'd loose my  hands off cruise trim
setting.

So as Scott B. said, I could possibly stiffen up the spring, I don't 
like this option because    Or I could use a trim actuator with more 
travel. I had not considered that  and will have to think about it.

However I do like the design of the Strong Pitch Trim system and would 
welcome the added space behind the panel if I removed the fiberglass 
spring trim system.  Strong now has a PWM controller for his trim system

for fine pitch adjustments at fast speeds. A problem I partially solved 
on the original system with a electric brake.

Scott



Ron Brown wrote:
> John,
>
> I don't think you will need more travel if you use the unmodified 
> factory ? shaped spring installed per the manual
>
> You'll just need to adjust its location to get the amount of up and 
> down trim needed for your plane.
>
> Ronnie
>
>
>
> ----- Original Message ----- From: "John Dibble"
<aminetech at bluefrog.com>
> To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
> Sent: Tuesday, January 31, 2006 6:56 PM
> Subject: Re: REFLECTOR: Elevator Trim Spring
>
>
>> Where can I get an actuator with more travel?
>>
>> John
>>
>> Scott Baker wrote:
>>
>>> While its interesting to think about the benefits of variable
geometric
>>> wings, canards, and winglets - lets remember the practical elements
of
>>> system design as it applies to weight, complexity of design and 
>>> maintenance,
>>> and of course cost.  The Beech Starship had a base list price of 
>>> $3.9M when
>>> it was introduced in 1989.  There are lots of cool things that would

>>> be fun
>>> to try - given relief from $$ constraints.  The subject of 
>>> pitch-trim has
>>> been discussed on the Reflector off and on in the past.  The basic 
>>> linear
>>> actuator/fiberglass spring system works well to my liking.  I happen
to
>>> think it is one of the finer flying attributes of the Velocity.  If
an
>>> aircraft does not have enough pitch trim (in cruise or in slow 
>>> flight) the
>>> answer in most instances is to re-mount (adjust the location) of the

>>> linear
>>> actuator so that it gives the needed travel.  Sometimes the
fiberglass
>>> spring needs stiffening - this can be done by adding a few plies of 
>>> glass -
>>> or replacing the spring with a new one from the factory.  A few 
>>> builders
>>> have installed linear actuators with an additional inch of travel 
>>> (in order
>>> to get enough up _and_ down trim).
>>> Scott Baker
>>>
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>
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