REFLECTOR: Speeds (Glenn Babcock)

Brooke Wolf bwolf1 at tds.net
Wed Jun 6 21:43:34 CDT 2012 

I found the following to be very useful in calibrating KIAS (knots indicated airspeed).  Just compute what you think your KTAS is using an E6B computer and compare to what the KTAS actually is using this:  http://spot.colorado.edu/~beale/TrueAirspeed/TrueAirspeedCalc.html.  Then, calibrate your airspeed indicator as necessary. 

Brooke

 
On Jun 6, 2012, at 9:00 PM, reflector-request at tvbf.org wrote:

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>   1. Re:  Speeds (Glenn Babcock)
>   2. Re:  What are you working on? (Milton Mersky)
> 
> From: Glenn Babcock <glennbabcock at roadrunner.com>
> Subject: Re: REFLECTOR: Speeds
> Date: June 6, 2012 8:38:09 PM EDT
> To: Velocity Aircraft Owners and Builders list <reflector at tvbf.org>
> Reply-To: Velocity Aircraft Owners and Builders list <reflector at tvbf.org>
> 
> 
> Steve,
> 
> I admit I've never tried that method, but I have done other testing to verify my static system dynamically. At first the port was on the fuselage forward of the door and was very inaccurate and fluctuating. I moved it under the door to a point where the flow is parallel, and since then I have had no unusual results in altitude or airspeed. 
> 
> I plan my long trips on known winds aloft, and arrive within a few minutes of the planned time. My EFIS reports winds aloft based on the GPS, airspeed and heading and it corresponds with the reported winds from XM weather real time. 
> 
> I'll try Scott's test and report back. 
> 
> Regards,
> Glenn
> 
> On Jun 6, 2012, at 7:16 PM, steve korney <s_korney at hotmail.com> wrote:
> 
>> 
>> Glenn...
>> 
>> Scott is spot on.... Even ATC reads your encoder for altitude... And the encoder gets it's information from the static port... It has to be accurate at cruise speed... Check it the way Scott mentioned... You may be surprised that it is not accurate dynamically...
>> 
>> Steve 
>> 
>> > From: glennbabcock at roadrunner.com
>> > Date: Wed, 6 Jun 2012 19:04:25 -0500
>> > To: reflector at tvbf.org
>> > Subject: Re: REFLECTOR: Speeds
>> > 
>> > Scott,
>> > 
>> > I'd be glad to take you up and listen to your apology. I have an IFR bird with a current pitot-static inspection and 3 GPSs including an IFR certified unit. I regularly fly 500+ mile trips using those airspeeds. My numbers are accurate. 
>> > 
>> > Regards,
>> > Glenn
>> > 
>> > On Jun 6, 2012, at 6:48 PM, Scott Derrick <scott at tnstaafl.net> wrote:
>> > 
>> > > Richard,
>> > > 
>> > > I think your doing very well at 170 KTAS..
>> > > 
>> > > I haven't seen a Std RG any faster when comparing TAS.
>> > > 
>> > > I don't have much confidence when I hear somebody reporting faster speeds than that with an STD RG. The longwing STD's are 5-10 knots slower than the orig STD.
>> > > 
>> > > There are two main reasons for incorrect airspeed reporting in homebuilts.
>> > > 
>> > > 1.) the pitot Static system has not been calibrated. Usually this is a result of a bad static reading. The only way I know of to check this is a very low(50 ft) pass over the runway at cruise speed. before the pass set your altimeter(on the ground) and verify the altitude on your altimeter, add 50 ft for comparison. During the low pass write down the altitude. If it is off by more than then 50 ft, you probably should adjust your static port. If it reads higher than it should you have too much static pressure, if lower you have too little. I adjusted mine with a small piece of aluminum tape in front of my port, this reduced the pressure and now I read the correct altitude. Because the IAS instrument is a comparator, comparing the pitot pressure against the static pressure, if your static port is off your airspeed indicator will be too.
>> > > 
>> > > 2.) The other reason is the confusion between GPS ground speed and TAS. Yes if you are in a no wind situation, very very rare, they are basically equal. but more often than not they are not and you will need to subtract a tailwind component or add a headwind component.
>> > > 
>> > > Scott
>> > > 
>> > > -------- Original Message --------
>> > > Subject: Re: REFLECTOR: Speeds
>> > > From: Richard J. Gentil <richard at naples-air-center.com>
>> > > To: Velocity Aircraft Owners and Builders list <reflector at tvbf.org>
>> > > Date: 06/06/2012 04:02 PM
>> > > 
>> > >> Hi Scott,
>> > >> 
>> > >> I am talking true airspeed. I am taking the alt, barometer, and OAT and using the KIAS I calculated my KTAS. I flew a triangular course and compared the GPS Ground speed to what the E6B was showing.
>> > >> 
>> > >> I pushed the mixture, prop, and throttle full foward and let the speed stabilize on the two EFIS screens and wrote down my numbers. I tested several altitudes from on the deck up to 6,500 feet.
>> > >> 
>> > >> Richard
>> > >> 
>> > >> Sent from my iPhone 4 Classic
>> > >> 
>> > >> On Jun 6, 2012, at 5:12 PM, Scott Derrick<scott at tnstaafl.net> wrote:
>> > >> 
>> > >>> Talking speeds kind be very frustrating.
>> > >>> 
>> > >>> The only speed I like to talk about is KTAS, Thats Knots True Air Speed
>> > >>> 
>> > >>> not statute miles nautical miles, not indicated airspeed true airspeed, and certainly not ground speed(GPS).
>> > >>> 
>> > >>> My IAS indicator has a TAS window, you select what your pressure altitude in reference to the OAT(upper window) and YOUR TAS will be indicated in the lower left window.
>> > >>> 
>> > >>> 
>> > >>> <jfaeejhi.jpeg>
>> > >>> 
>> > >>> You can also fly a triangular course, using the GPS ground speed , and compute a fairly accurate TAS from that.
>> > >>> 
>> > >>> And of course some of the higher end glass cockpits can compute it for you.
>> > >>> 
>> > >>> And if flying very near to sea level on a std day temperature wise and assuming your IAS indicator is close to cal, it will show TAS.
>> > >>> 
>> > >>> So Richard when you say 170 kts, what kind of speed are you talking about and how are you measuring it?'
>> > >>> 
>> > >>> Scott
>> > >>> --
>> > >>> Talk sense to a fool and he calls you foolish.
>> > >>> Euripides
>> > >>> _______________________________________________
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>> > > 
>> > > -- 
>> > > While I see many hoof marks going in, I see none coming out. It is easier to get into the enemy's toils than out again.
>> > > Aesop
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> 
> 
> 
> From: "Milton Mersky" <miltonm at airmail.net>
> Subject: Re: REFLECTOR: What are you working on?
> Date: June 6, 2012 2:09:23 PM EDT
> To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
> Reply-To: Velocity Aircraft Owners and Builders list <reflector at tvbf.org>
> 
> 
> Kurt:
>  
> If you did'nt have bad luck you would not have any luck at all.
>  
> Milton
> ----- Original Message -----
> From: nmflyer1 at aol.com
> To: reflector at tvbf.org
> Sent: Wednesday, June 06, 2012 9:23 AM
> Subject: Re: REFLECTOR: What are you working on?
> 
> Well,
>  
> I had hoped to have the Fuselage painted by now. But Nooo.  The new paint gun I bought would not spray right. So I had to go back to my old siphon gun. That caused so much airborne mist that 1 exhaust fan would not clear the booth. I turned on the second, and found that I did not have enough filtered inlet surface to meet the exhaust demand. That caused the booth walls to be pulled inward. Since it is Cottonwood Tree season right now, that sucked airborne cotton into the booth.
>  
> See how my luck is working at this point?  :0
>  
> Primer done and finish sanded. Waiting for the new replacement gun to show up so that I can spray some color on Thursday (barring any other disasters).
>  
> Send me some good vibes.. I could use them about now.
>  
> Pic attached.
>  
> Kurt
>  
> 
> 
> 
>  
> -----Original Message-----
> From: Reiff Lorenz <Reiff at lorenz.com>
> To: reflector <reflector at tvbf.org>
> Sent: Wed, Jun 6, 2012 8:02 am
> Subject: REFLECTOR: What are you working on?
> 
>  
> The Reflector has been quiet this week. Hopefully that means that everyone is busy flying or building.
>  
> I'd love to hear what the Velocity community is working on. If your bird is in the air tell us where you're flying.
>  
> I've been spending my time on the wings; aileron torque tubes, wiring for nav/pos/strobe lights, and final fitting of the rudders. I'm trying to complete all the wing tasks that can be done without them attached to the fuselage.
>  
> Reiff Lorenz, Dayton, OH
> Velocity XL-RG, 33% complete
>  
>  
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> 
> 
> _______________________________________________
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> 
> 
> _______________________________________________
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