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Dynon Pitot / Angle of Attack

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maarten versteeg

Joined: 15 May 2007
Posts: 37
Location: San Antonio

Posted: Thu Jan 31, 2008 10:41 am Post subject: Dynon Pitot / Angle of Attack

Hello group,



I am considering using a Dynon for my 601 instrument

panel. Even though I have never flown with an AOA

indicator it seems a useful addition to my panel.

My question is now: can I only use the Dynon AoA

indicator when I buy their pitot or can I use any

angle of attack sensor?



Maarten Versteeg

601xl plansbuilding wings

_________________
Maarten Versteeg
601XL scratch building wings

amyvega2005(at)earthlink.
Guest

Posted: Thu Jan 31, 2008 11:36 am Post subject: Dynon Pitot / Angle of Attack

Its a great toy, however since the 601xl does not have a breaking stall, which is what you want to avert hence the AOA, its just an added bell and whistle.  CASe and point:

the AOA is to make the plane does not stall on tight turns on final or shallow turns on final at slow speeds.

the 601 can be in slow flight at below the green arch and not break into spin, it just drops at 1000 fpm, until you push the stick or apply a little power.  

The AOA shows when the plane has no more lift based on the green arch numbers you program in.  If the 601 flys straight and level at below the green arch the AOA becomes useless.

It could be usefull in a turn, preventing a side slip stall.  But you need to have brass balls to turn the 601 from base to final tightly (45deg or <), at less than 55 mph.

Juan



--

dredmoody(at)cox.net
Guest

Posted: Thu Jan 31, 2008 12:13 pm Post subject: Dynon Pitot / Angle of Attack

Since we all have opinions...... my opinion is that it is just as important  to avoid the stall/mush phenomenon in which the plane  loses altitude precipitously on approach and departure as it is to avoid a stall/spin event in the same environment. 



The decision to have an AOA display and learn to use it is based on how you want to detect the threashold of the stall. If you feel that you can detect the situation and act to avert it with out an AOA system, that's as good a choice as choosing to install one. But saying that the plane has docile stall characteristics is not (for me) a good reason to dismiss the usefulness of an AOA system. 



Dred



Dred

 

---- Juan Vega <amyvega2005(at)earthlink.net> wrote: 

[quote] 

 

 Its a great toy, however since the 601xl does not have a breaking stall, which is what you want to avert hence the AOA, its just an added bell and whistle.  CASe and point:

 the AOA is to make the plane does not stall on tight turns on final or shallow turns on final at slow speeds.

 the 601 can be in slow flight at below the green arch and not break into spin, it just drops at 1000 fpm, until you push the stick or apply a little power.  

 The AOA shows when the plane has no more lift based on the green arch numbers you program in.  If the 601 flys straight and level at below the green arch the AOA becomes useless.

 It could be usefull in a turn, preventing a side slip stall.  But you need to have brass balls to turn the 601 from base to final tightly (45deg or <), at less than 55 mph.

 

 

 Juan

 

 --

victorbravo(at)sbcglobal.
Guest

Posted: Thu Jan 31, 2008 12:47 pm Post subject: Dynon Pitot / Angle of Attack

Yeah but what about below the WHITE arc on the airspeed? Or what about 

the point at the bottom of the green arc where the airplane starts to 

mush and develops a very dangerous high sink rate? An AOA indicator 

should allow you to fly a landing approach at the optimum 

speed/angle/energy regardless of what happens when the angle gets too 

high. A runaway rate of descent with no ability to arrest that descent 

will crash an airplane too.



Also, if you have an airplane set up so it will not stall with the stick 

all the way back then you are giving away the last several miles an hour 

of slow flight ability. In a crash landing, there is a CUBED function of 

energy versus velocity. Every two or three miles an hour you can slow 

the airplane down before you hit something makes a significant reduction 

in the amount of destructive energy that is absorbed by the airplane and 

the occupants.



A little extra flight instruction, a little more skill-building on the 

pilot's part, will allow your airplane to fly with better performance 

(within reason) and be able to land safely in a shorter distance whether 

for fun or survival.



I pissed off several canard enthusiasts one day (who were bowing, 

praying and chanting in the general direction of Mojave, Caifornia) when 

I said ...  "when you design an airplane to be idiot-proof, you pretty 

much define the market for it"

 	  Quote: 	
		   Its a great toy, however since the 601xl does not have a breaking stall, which is what you want to avert hence the AOA, its just an added bell and whistle.  

 If the 601 flys straight and level at below the green arch the AOA becomes useless.

DaveG601XL

Joined: 27 Oct 2006
Posts: 351
Location: Cincinnati, Oh

Posted: Thu Jan 31, 2008 1:11 pm Post subject: Re: Dynon Pitot / Angle of Attack

Maarten,



To go back to your original question, the best answer you will likely get is "probably, yes, but it depends."  All of the AOA sensors I have personally seen are differential pressure systems.  The input air, either via a two-pronged pitot-like probe or two holes, one above and one below the wing leading edge provide two air pressures to a differential pressure readout device.  Initially, the readout device, be it a steam gauge or electronic indication, is just a dumb indication of differential pressure.  By YOUR calibration, on YOUR airplane, the differential pressure that the particular set of probes sends to the particular readout device at or near stall become your critical AOA values.  



So it all depends on if the probe supplies the range of pressures that match the range of your indicator.  The best bet would be to use hardware that is known to be compatible.  



Good luck,

_________________
David Gallagher
Cincinnati, OH area

n801bh(at)netzero.com
Guest

Posted: Thu Jan 31, 2008 2:43 pm Post subject: Dynon Pitot / Angle of Attack

Bill. I just want to say that was VERY well written and expressed. My take on this is,,,, Fly the plane from the seat of the pants. If one needs some gauge to tell you him/her how close the plane is to a stall several things might happen.1- The bottom might drop out during a wind sheer siuation,.2- keeping your head in the cockpit looking at a gauge might let you run into another plane or terrain. God forbid if the pitot tube/sensor and/or the gauge goes bad at the worst time and you are trusting it.... YMMV 

do not archive

Ben Haas

N801BH

www.haaspowerair.com



-- Bill Berle <victorbravo(at)sbcglobal.net> wrote:

--> Zenith-List message posted by: Bill Berle <victorbravo(at)sbcglobal.net>

Yeah but what about below the WHITE arc on the airspeed? Or what about 

the point at the bottom of the green arc where the airplane starts to 

mush and develops a very dangerous high sink rate? An AOA indicator 

should allow you to fly a landing approach at the optimum 

speed/angle/energy regardless of what happens when the angle gets too 

high. A runaway rate of descent with no ability to arrest that descent 

will crash an airplane too.



Also, if you have an airplane set up so it will not stall with the stick 

all the way back then you are giving away the last several miles an hour 

of slow flight ability. In a crash landing, there is a CUBED function of 

energy versus velocity. Every two or three miles an hour you can slow 

the airplane down before you hit something makes a significant reduction 

in the amount of destructive energy that is absorbed by the airplane and 

the occupants.



A little extra flight instruction, a little more skill-building on the 

pilot's part, will allow your airplane to fly with better performance 

(within reason) and be able to land safely in a shorter distance whether 

for fun or survival.



I pissed off several canard enthusiasts one day (who were bowing, 

praying and chanting in the general direction of Mojave, Caifornia) when 

I said ...  "when you design an airplane to be idiot-proof, you pretty 

much define the market for it"

 	  Quote: 	
		   Its a great toy, however since the 601xl does not have a breaking stall, which is what you want to avert hence the AOA, its just an added bell and whistle.  

 If the 601 flys straight and level at below the green arch the AOA=========================          - The Zenith-L=========================================================================            &n                     -Matt Dralle, List======================================

 
	




_____________________________________________________________

Protect your eyes.  Click here for free information on eye care.

   [quote][b]

amyvega2005(at)earthlink.
Guest

Posted: Thu Jan 31, 2008 3:54 pm Post subject: Dynon Pitot / Angle of Attack

The comment about ideiot proofing I agree totally about, thats what I think of the AOA, just anotherthing to marvel at in the cocckpit , when you should be flying the plane.



Juan



--

engineerguy3737(at)yahoo.
Guest

Posted: Thu Jan 31, 2008 4:19 pm Post subject: Dynon Pitot / Angle of Attack

I dont know of any other sensor that will work with

our pitot. But, that doesn't mean there aren't any. If

I remember correctly, someone out there does make an

external indicator that works off of the serial stream

we put out.



Dan Lykowski

Dynon Avionics



--- Maarten Versteeg <maarten.versteeg(at)swri.org>

wrote:



 	  Quote: 	
		   

 <maarten.versteeg(at)swri.org>

 

 Hello group,

 

 I am considering using a Dynon for my 601 instrument

 panel. Even though I have never flown with an AOA

 indicator it seems a useful addition to my panel.

 My question is now: can I only use the Dynon AoA

 indicator when I buy their pitot or can I use any

 angle of attack sensor?

 

 Maarten Versteeg

 601xl plansbuilding wings

 



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tshankland(at)sbcglobal.n
Guest

Posted: Thu Jan 31, 2008 7:15 pm Post subject: Dynon Pitot / Angle of Attack

Maarten,

Don't listen to all this negativity, if you want to use the AOA 

indicator do it. Look in the archives of "AOA for your Dynon". I 

submitted some pictures of a sensor I made using copper tubing and 

aluminum. Since you all ready bought the Dynon why not use all the 

functions it has. I have mine working and I do consult it especially on 

turns in the landing pattern. I've flown for 40 years without one and 

certainly can now but I believe he who dies with the most toys wins.

Tim Shankland



Maarten Versteeg wrote:



 	  Quote: 	
		   

 <maarten.versteeg(at)swri.org>



 Hello group,



 I am considering using a Dynon for my 601 instrument

 panel. Even though I have never flown with an AOA

 indicator it seems a useful addition to my panel.

 My question is now: can I only use the Dynon AoA

 indicator when I buy their pitot or can I use any

 angle of attack sensor?



 Maarten Versteeg

 601xl plansbuilding wings

Ron Lendon

Joined: 10 Jan 2006
Posts: 685
Location: Clinton Twp., MI

Posted: Thu Jan 31, 2008 7:49 pm Post subject: Re: Dynon Pitot / Angle of Attack

Maarten,



Tim Shankland I beleive made a post (#49240) about bending up some copper tubing and it is in the archives.  Great idea Tim.  



Anyway, I have the Dynon AOA Pitot tube and it is quite pricey.  Being that the device is an electronic instrument I gotta believe there are variables that can be adjusted to compensate for whatever pressure differentials you are reading.  Tim's post reveals that truth.



If I had seen the copper tubing design first I would have most likely used that method.

_________________
Ron Lendon
WW Corvair with Roy's Garage 5th bearing
CH 601 XLB
N601LT - Flying
http://www.mykitlog.com/rlendon
Corvair Engine Prints:
https://sites.google.com/site/corvairenginedata/

Terry Phillips

Joined: 11 Jan 2006
Posts: 346
Location: Corvallis, MT

Posted: Fri Feb 01, 2008 9:53 am Post subject: Dynon Pitot / Angle of Attack

Maarten



I've not flown with any AOA indicator, but I am very interested in using 

one. I have considered hooking the Dynon pitot plumbing the both the ram 

air orifice and the angled orifice to the Dywer Minihelic pressure gage 

that is frequently used for homebuilt AOA indicators. It seems to me that 

you could calibrate a generic AOA indicator (i.e., Dynon, homebuilt, 

whatever) for any pressure source that produces a differential pressure 

proportional to the angle of attack. I've also thought of making a pitot 

similar to ones used the the F-117 fighter. I'm attaching a photo of one of 

those pitots. As you can see, this pitot has 5 orifices, a direct ram air 

orifice facing forward, and 4 that are on faces ~45° up, down, right, & 

left. For AOA input, the right & left orifices would be eliminated, and the 

top and bottom orfices would be plumbed to the AOA gage.  There may be a 

static port on the F-117 pitot as well--I forgot to look.



Whether a different pitot would work with the Dynon would depend on what 

sort of curve fit is used in the Dynon software to calculate the AOA from 

the  differential pressure signal. Probably, only Dynon could give you a 

definitive answer to this question.



Terry

At 12:36 PM 1/31/2008 -0600, you wrote:

 	  Quote: 	
		  Hello group,



I am considering using a Dynon for my 601 instrument

panel. Even though I have never flown with an AOA

indicator it seems a useful addition to my panel.

My question is now: can I only use the Dynon AoA

indicator when I buy their pitot or can I use any

angle of attack sensor?



Maarten Versteeg

601xl plansbuilding wings


	




Terry Phillips

ttp44~at~rkymtn.net

Corvallis MT

601XL/Jab 3300 s .. l .. o .. o.. w build kit - Tail, flaps, & ailerons are 

done; working on the wings

http://www.mykitlog.com/N47TP/

DSCN2687B.jpg

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_________________
Terry Phillips
Corvallis, MT
ttp44<at>rkymtn.net
Zenith 601XL/Jab 3300 slow build kit - Tail feathers done; working on the wings.

japhillipsga(at)aol.com
Guest

Posted: Fri Feb 01, 2008 9:53 am Post subject: Dynon Pitot / Angle of Attack

Ed, I agree with both you and Juan. As we fly the XL near, at or over gross a lot of the time the power off stall can be felt and noticed when the plane is heavy. That should be at the weight you adjust the sensor probe for a little margin of safety. At or near gross when the dial indicator gets in the yellow ban you had better have the wheels near the ground, as you may well remember? because she it coming down. Another reason to install the AOA LRI is because you don't have to worry much about density altitude. When the plane is going fast enough to fly the dial moves into the green ban, pull back and your flying. Course if your on some short strip you might want to compute the DA. I never used one in the years and planes I'd flown until I installed one in my XL. I'll never fly/build another without an AOA LRI. My 2 cents, best regards, Bill 

 

 

 --

psm(at)att.net
Guest

Posted: Fri Feb 01, 2008 10:25 am Post subject: Dynon Pitot / Angle of Attack

I think it sometimes helps to look at things backwards.  In this case 

that means considering how closely you can safely fly without 

stalling rather than simply avoiding a stall.



An AOA or LRI allows you to pick a margin above your current stall 

speed and fly your approach with only that margin.  That means 

landing in the minimum space and at the minimum speed while still 

maintaining safety margins.  It also means each pilot can pick his 

own safety margin.  This kind of precision flying is just not 

possible when only the airspeed indicator is used to control approach speeds.



If your only use of an AOA or LRI is as a stall warning device, you 

might do better to just install a stall warning device.



Paul

XL fuselage

At 09:49 AM 2/1/2008, you wrote:

 	  Quote: 	
		  Ed, I agree with both you and Juan. As we fly the XL near, at or 

over gross a lot of the time the power off stall can be felt and 

noticed when the plane is heavy.

Dave Nixon

Joined: 20 Sep 2007
Posts: 25

Posted: Fri Feb 01, 2008 1:04 pm Post subject: Re: Dynon Pitot / Angle of Attack

The beauty of the Dynon AOA is that after initialized and you set up the parameters for your airplane, it has the capability to  produce an AUDIO alert similar to a Cessna or Piper to alert you to an upcoming stall condition.  You can even wire in an external speaker if your intercom doesn't provide that capability.  Also, I have mounted a .5AMP LED indicator lamp on my panel in my immediate scan zone as backup.    Those that think you have to ' Bury Your Head Inside ' to view indications with a Dynon are not thinking outside the box or airplane.  It is a great safety device.  I have customized my pitot system to mimic Jim's copper tube system and installed a static port receptacle just behind the co-pilot's seat (just aft of the bend) Hanging the wings this week so I should be able to give a report soon. 

Dave Nixon 

CH 601XL Jabiru3300

95% DONE with 50% To Go

maarten versteeg

Joined: 15 May 2007
Posts: 37
Location: San Antonio

Posted: Fri Feb 01, 2008 5:44 pm Post subject: Dynon Pitot / Angle of Attack

Thanks for all the replies, a lot to think about. I have made

some flight in an zenith 601 before and one of the arguments

for the selection was the great view, it almost feels like

sitting outside. I agree, one of the great excitements of

flying is looking outside and that is what I plan to do often,

having been an hang-glider pilot, flying without any

instruments, just feeling the the air is great. Adding a tool

in the cockpit should not stop me from spending most of the

time looking outside and feeling the plane.

Sometimes I would like to use my plane for other missions though,

for flying x-country an GPS device makes flying even simpler,

and I could defend the position that it allows you to spend more

time looking outside the cockpit. Concerning the pitot, at some

point I could see myself trying to get an instrument rating using

my zenith, clearly not to fly any hard IFR but to get more

experienced flying the plane, most of the required instruments

for that can later be added in the cockpit, but the pitot is

one of the few items that lives far outside on the wing and may

be harder to change later. As said so many options to think

(dream) about.



Maarten Versteeg

601xl plansbuilding wings

_________________
Maarten Versteeg
601XL scratch building wings

Mark Burton

Joined: 10 Jan 2006
Posts: 74

Posted: Sat Feb 02, 2008 9:40 am Post subject: Re: Dynon Pitot / Angle of Attack

Hello Zenith folks,



If you want to maintain a safe margin above the stall but not have your head buried in the cockpit, you could fit a "SmartASS" device that my company, Smart Avionics manufactures.



This unit measures airspeed and vertical acceleration and talks to the pilot through the headset. No dials or lights to look at so you can keep your eyes out of the window all the way down the approach.



One mode of operation for this unit is as a "stall margin preserver" that tells the pilot (through their headset) if they are diverging from a chosen approach speed. If they pull G, that gets noticed instantly so it's a bit like having an AOA instrument compared to just using an ASI alone.



The reason I invented it was because I wanted to keep my eyes out of the cockpit while still flying a very accurate approach.



Details can be found at www.smartavionics.com



Cheers,



Mark



PS - I agree that being able to fly your aircraft by feel alone and not looking at the instruments is a great skill to have, but if you are as dozy a pilot as I am, you need all the help you can get!

dredmoody(at)cox.net
Guest

Posted: Sat Feb 02, 2008 10:59 am Post subject: Dynon Pitot / Angle of Attack

Is the prop balancer available for shipping to the  USA. If not, when is the new model expected. What cost in American dollars  including shipping?

  

 Dred

 [quote]   ---

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