REFLECTOR: Static error

[Laurence Coen]

Let's not forget that your altimeter and transponder depend on an accurate 
static pressure.  I think that a speed dependant static error would be a 
safety issue.

Larry Coen
N136LC

----- Original Message ----- 
From: "Pat Shea" <xl340hp at yahoo.com>
To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
Sent: Wednesday, April 12, 2006 1:17 AM
Subject: Re: REFLECTOR: Cirrus v. Velocity


> Scott,
>
> I couldn't agree more that there's potentially large
> Indicated Air Speed (IAS) discrepancies in many V's
> given the multitude of Velocity pitot/static locations
> I've seen (and i'm sure you've seen more). On the
> other hand, you'd be hard pressed to find a flying V
> without at least a hand held GPS. To determine your
> ballpark cruising True Air Speed (TAS) using GPS, all
> you have to do is fly at 7,500', set your power at 75%
> (combined RPM and MP total of 48 is close enough), and
> turn some shallow bank circles (say half standard
> rate) while maintaining altitude, and then average
> your highest and lowest GPS ground speeds. Yes this
> method can certainly be refined, but it's simple and
> is way more accurate than using potentially erroneous
> IAS to determine TAS.
>
> Pat
>
> --- Scott Baker <sbakr at comcast.net> wrote:
>
>> I have noticed that many Velocity aircraft vary in
>> their indicated air speed
>> due to either an un-calibrated air speed indicator
>> and the position of the
>> static port.  Calibrating the air speed indicator at
>> the local avionics shop
>> is a good thing to do - but that still leaves the
>> possibility of air speed
>> errors caused by the static port.  I trust the
>> Cirrus air speed because of
>> its being certified.  It's great to get a fast
>> moving certified aircraft to
>> do some side-by-side flights with the Velocity, just
>> to make sure both air
>> speed "meters" are indicating the same during
>> formation flight.
>> 200 knots indicated in the Denver area is
>> outstanding.  The true air speed
>> must be "right on up there".  I have flown the
>> company demonstrator (310hp)
>> at Front Range and at Colorado Springs - giving demo
>> rides with 4-people on
>> board and about 40-gallons of fuel - and the
>> aircraft performed quite well.
>> I've talked to several Cirrus 22 owners who have
>> taken a demo ride in the XL
>> with the Continental IO-550.  All of them seemed
>> impressed - and most
>> admitted the Velocity had a small but noticable
>> performance advantage.  Most
>> were looking for a way to reduce the cost of
>> aircraft ownership.  Several of
>> the Cirrus owners were upset with the cost of
>> aircraft insurance.
>> Sunny Eymann recently sold his Velocity XL in favor
>> of a Cirrus 22 because
>> he liked the feel of the Cirrus in a cross-wind
>> landing - something that is
>> an everyday event in Key West.  Still, he likes the
>> Velocity - he just felt
>> the Cirrus was the right aircraft for him.
>> Random thoughts.
>> Scott B.
>
>>
>
>
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