REFLECTOR: Elevator Trim Spring

[John Dibble]

Chuck,
I think the issue is that if you're trimmed for cruise and the trim system fails, it
will require a lot of aft stick force to land.  However, for an IDENTICAL failure
scenario with a stiffer spring, it seems to me that the required stick force will be
identical, because you will not be using the full capacity of the spring at cruise,
only the identical force that you used with the weaker spring.  Of course with the
stronger spring you can trim at more extreme conditions and then the landing aft force
will be greater.  But flying with inadequate trim seems just plane silly (pun
intended).  Seems like in the event of trim failure, the autopilot could be used to
assist with the stick force.

John

Chuck Jensen wrote:

> 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
> >
> >