REFLECTOR: Elevator Trim Spring

[Scott Derrick]

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  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.   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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