REFLECTOR: Elevator Trim Spring

Scott Derrick scott at tnstaafl.net
Thu Feb 2 08:42:52 CST 2006 

So's mine...

steve korney wrote:
>
> Don't forget Scott that the sparrow trim also has to fight the trim 
> spring...  So, I use a light trim spring and have a very soft elevator 
> control force up to my top speed of about 170 knots...  My elevator is 
> pointing up (down elevator) about 5/8 of an inch at 170 knots...
>
>
> 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 11:27:14 -0700
>
> 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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