REFLECTOR: Elevator Trim Spring

[Scott Derrick]

Steve,

I have the strainer installed.  I've flown with and with out.

The strainer seems to reduce the frequency of trim change needed as you 
change airspeed.

On my plane it certainly doesn't "take care" of trim in cruise. 

Its installed per the plans, but that doesn't mean its set right.

My take on the matter is the faster the plane, or in other words, the 
greater the range of speed between top end cruise and stall, the greater 
the range of trim required. 

With my last engine I stalled around 65 KIAS, and cruised at 175 
KIAS(sea level).   So, maybe the folks that are having a hard time 
getting enough up and down trim are the faster planes?  Or lighter pilots?

Scott

steve korney wrote:
>
> Guys.....
>
> The sparrow strainer takes care of the trim in cruise and top 
> speed...  If it's set right...
>
>
> Best... Steve
>
>
>
> ----Original Message Follows----
> From: Scott Derrick <scott at tnstaafl.net>
> Reply-To: Velocity Aircraft Owners and Builders list <reflector at tvbf.org>
> To: Velocity Aircraft Owners and Builders list <reflector at tvbf.org>
> Subject: Re: REFLECTOR: Elevator Trim Spring
> Date: Wed, 01 Feb 2006 08:08:24 -0700
>
> 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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