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Author Topic: ASI  (Read 18180 times)

Offline FlyboyGil

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ASI
« on: March 18, 2008, 10:52:00 PM »
I got this question from a Myspace friend who is learning to fly. I think it's a good question, and decided to post it here to giver her an answer.

HOW CAN YOU IDENTIFY IF THE SPEED INDICATOR BECOMES INOPERATIVE? (I assume it means when operating improperly) OBVIOUSLY THIS IS DURING FLIGHT !

I KNOW THE POTENTIAL ERRORS (WATER,LAG,DENSITY,POSITION,ICING)

I WILL PROBABLY BE ASKING FOR MORE HELP AS I GO ALONG, I HOPE IT'S OKAY

THANKS......KIM
« Last Edit: March 18, 2008, 10:57:14 PM by FlyboyGil »
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Offline G-man

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Re: ASI
« Reply #1 on: March 19, 2008, 12:27:12 AM »
Quote from: FlyboyGil on March 18, 2008, 10:52:00 PM
I got this question from a Myspace friend who is learning to fly. I think it's a good question, and decided to post it here to giver her an answer.

HOW CAN YOU IDENTIFY IF THE SPEED INDICATOR BECOMES INOPERATIVE? (I assume it means when operating improperly) OBVIOUSLY THIS IS DURING FLIGHT !

I KNOW THE POTENTIAL ERRORS (WATER,LAG,DENSITY,POSITION,ICING)

I WILL PROBABLY BE ASKING FOR MORE HELP AS I GO ALONG, I HOPE IT'S OKAY

THANKS......KIM

I am here to help..

If you bring the aircraft back to a hover----and the ASI is still indicating 100kts, one can assume that it is inoperative.   ::whistle:: ::whistle::
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Offline PiperGirl

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Re: ASI
« Reply #2 on: March 19, 2008, 01:41:39 AM »
Quote from: G-man on March 19, 2008, 12:27:12 AM
I am here to help..

If you bring the aircraft back to a hover----and the ASI is still indicating 100kts, one can assume that it is inoperative.   ::whistle:: ::whistle::

 ;D  ;D ::rofl::
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Offline Frank N. O.

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Re: ASI
« Reply #3 on: March 19, 2008, 01:57:42 AM »
Quote from: G-man on March 19, 2008, 12:27:12 AM
I am here to help..

If you bring the aircraft back to a hover----and the ASI is still indicating 100kts, one can assume that it is inoperative.   ::whistle:: ::whistle::
Me thinks that if you do that with a proper flying machine then the ASI soon won't be the only thing that'll be inop! :D

Gil: Another lady pilot?  8) |:)\

Frank
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Offline Mike

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Re: ASI
« Reply #4 on: March 19, 2008, 05:50:17 AM »
we should give him a REAL answer at some point I think . . .
That was the initial intent of this thread.

Only, I don't have a clue if I could explain that.....
any stuck-wing guys left in here??
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Offline Franz

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Re: ASI
« Reply #5 on: March 19, 2008, 10:40:17 AM »
In gliders you try to avoid using the ASI, because of the lag. What you do is you look at the horizon and try to figure out how fast you're going. If you don't see it at all, you're either pretty fast (houses getting bigger) or way too slow (houses? I can only see sky). And then there's a "normal" position which indicates you're soaring along at a reasonable speed.
In planes you'd also have to take engine power into consideration, but if the ASI fails, maybe the engine will, too :o  ??? ::sweat::

And just in case all my ability to explain things got lost on my first day of Easter holyday, here's a little drawing to illustrate what I just wrote:
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Offline G-man

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Re: ASI
« Reply #6 on: March 19, 2008, 03:51:22 PM »
Quote from: Mike on March 19, 2008, 05:50:17 AM
we should give him a REAL answer at some point I think . . .
That was the initial intent of this thread.

Boring Boring Boring..However you are right..

There are several ways that it could be determined..

1. As above..bring it to a hover.
2. Maintain a constant power setting and then raise the nose for 5 seconds, and lower the nose for 5 seconds. Observe the ASI, if it is working correctly, it should indicate a decrease followed by an increase in airspeed.
3. Maintain a constant attitude and vary the power..observe the ASI..It should vary with the power.
4. Observe the wind..assuming negligible wind..one could fly low over a freeway and time your self between mileage signs. A simple use of mathematics would determine the accuracy of your ASI.
5. Fly formation with another aircraft and compare ASI readings.
6. Ask your instructor--assuming he/she is sitting next to you.
7. Observe indications on your altimeter and VSI. They all use the same static feed. If they are reading INCORRECTLY, then you can assume that your ASI would also be reading incorrect.
8. Land at an avionics ship and pay copious amounts of hard earned cash to have them run a check.
9. Who needs one anyway..you have a stick shaker warning on the low end and that "wings ripping off" sound on the high end..just fly at a speed between the 2 and you will be fine.  ::whistle:: ::whistle::

I rarely use mine so this is about the best I can do.
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Offline Mike

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Re: ASI
« Reply #7 on: March 19, 2008, 04:06:21 PM »
Quote from: Frank N. O. on March 19, 2008, 01:57:42 AM

Gil: Another lady pilot?  8) |:)\

Frank

yeah, Gil !
Why don't you bring her in here?
She could ask all kinds of questions (which she may or may not get straight answers for in return  ;) ;D ) and I am sure the other girls in here would like to have another girl join.

I sure hope we don't scare off the young aviator people in here..... haven't seen many join lately....  ::thinking::
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Offline leiafee

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Re: ASI
« Reply #8 on: March 19, 2008, 06:24:31 PM »
Pitch and Power!

I know what airspeed the tommyhawk'll do at various combination of power and nose attitude.  If the ASI read significantly different thn I'd wonder about it.

I also have a reasonable "feel" for how the aerplane handles in fast and slow flight -- if it was significantly out, that should be a clue too.

Both of those things came with more practice than I had an a new student pilot though.
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Offline FlyboyGil

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Re: ASI
« Reply #9 on: March 19, 2008, 11:07:17 PM »
Quote from: Mike on March 19, 2008, 04:06:21 PM
Quote from: Frank N. O. on March 19, 2008, 01:57:42 AM

Gil: Another lady pilot?  8) |:)\

Frank

yeah, Gil !
Why don't you bring her in here?
She could ask all kinds of questions (which she may or may not get straight answers for in return  ;) ;D ) and I am sure the other girls in here would like to have another girl join.

I sure hope we don't scare off the young aviator people in here..... haven't seen many join lately....  ::thinking::

I see she has joined now. She's the newest Member BREISABUTT!!! WELCOME KIMMY!!!!
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Offline Rooster Cruiser

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Re: ASI
« Reply #10 on: March 19, 2008, 11:38:55 PM »
ASI failures depend on the type of problem encountered.  An ASI in fixed wing aircraft measures the relative pressure difference between the Pitot (Ram Air) and Static source, which is measured from alongside the fuselage.  If the Static source becomes blocked, the ASI will act like an altimeter.  If the Pitot becomes blocked, the ASI will read zero or may show no change in airspeed with changes in attitude or power.

I actually had several ASI failures in my Platypus when I started working here in the desert.  The airplane was parked outside under an awning (still is) but it did not have a Pitot cover.  Over the months, a bunch of dust gathered into the Pitot.  This did not affect my ASI while in flight unless I flew into a cloud at altitude.  The moisture in the air would freeze onto the dust, which was insulating the inside of the Pitot tube, rendering Pitot Heat useless.  If I was in cloud for more than a minute, I would watch in horror as BOTH my ASI's would wind down and read zero at FL280!  I would then have to fly by attitude and power settings only until it became time to descend.  Then as I would descend into warmer air, the frost inside the Pitot would melt and my ASI's would once again function normally.  My avionics shop finally figured it out much to my relief, but not after I had replaced the Pitot Head and had it happen AGAIN!

RC
« Last Edit: March 20, 2008, 03:24:39 AM by Rooster Cruiser »
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Offline Mike

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Re: ASI
« Reply #11 on: March 20, 2008, 12:37:37 AM »
hmmmm.... ::thinking::

seems like there is a valuable lesson hidden inside RC's story....
about pitot tube covers and how and when to use them. . .
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Offline Rooster Cruiser

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Re: ASI
« Reply #12 on: March 20, 2008, 03:20:50 AM »
No kidding Mike.  For want of a $200.00 Pitot cover, I spent about $10,000.00 in repairs! ::eek:: ::unbelieveable::  Not to mention the added "Pucker Factor" that went into flying around with a defective ASI... or two!   ::banghead::
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Offline TheSoccerMom

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Re: ASI
« Reply #13 on: March 20, 2008, 04:58:31 AM »
 :)

Our covers are free...  a side benefit of having an excellent sewer among the pilots...  he made a set of perfectly-sized pitot covers for each airplane out of heavy saddle leather....  they don't get brittle in the cold, or too loose in the heat.  And one set will last you for years and years.....

The only bad part is that other people have tried to swipe them!!   ::complaining:

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Offline happylanding

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Re: ASI
« Reply #14 on: March 20, 2008, 06:41:25 PM »
Quote from: FlyboyGil on March 19, 2008, 11:07:17 PM
I see she has joined now. She's the newest Member BREISABUTT!!! WELCOME KIMMY!!!!

More chicks in the forum! Yeppeeee!
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