Altitude - Barometer - Accuracy

Technical questions, advice, sharing information etc (aircraft, engines, instruments, weather and such)
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Morph
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Postby Morph » Sun Nov 06, 2005 8:36 am

DarkHelmet wrote: I am more than willing to lend you my manuals ;) Let me know how I can get em to you!
DH
Hey DieselFan this is a great offer from DH, but it is still important to get your own set to keep as reference.
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Postby DarkHelmet » Sun Nov 06, 2005 10:10 am

It was more an offer to tie him over until his next lesson than anything else ;) I am on the West Rand and think he is on the East - would probably be quicker just to bel his instructor and getting them from him.

GO Diesel GO - I am looking forward to your next update!
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Postby krusty » Sun Nov 06, 2005 12:42 pm

Morpheus wrote:The original altitude of the airfield was probably measured by land surveyors or something.
Correct.
Morpheus wrote:Today you can use a GPS to get a fairly accurate, within a few feet, measurement.
That depends on your definition of "fairly". GPS elevation is nowhere near as accurate as GPS position. Typically, without the use of WAAS and with a "normal" level of signal coverage, GPS elevation will be accurate to 30 - 50 feet.

Sorry, I'm 7500ing the thread.

PS. Well done on lesson 1 DF - hope you're enjoying it!!!!
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Postby DieselFan » Mon Nov 07, 2005 10:35 am

Morpheus wrote:Have you paid for your groundschool yet? if so ask the instructor to give you the manual. Otherwise I bought a book from

http://www.amazon.co.uk

Microlight Pilot's Handbook by Brian Cosgrove at 14 pounds ex shipping.

Some of the flying schools here in CT use it and it is good.
How is this book different to the one I'll end up buying for my groundschool? Could I use this one instead? Cause at that price I can do it now!
DarkHelmet wrote:It was more an offer to tie him over until his next lesson than anything else ;) I am on the West Rand and think he is on the East - would probably be quicker just to bel his instructor and getting them from him.

GO Diesel GO - I am looking forward to your next update!
Thanks for the offer, but when something interests me I will easily travel 500km so beware 8). Besides west rand is not far from Sandton.

To be honest though, as I want to stick to a fixed amount of money allocated to ML, I wasn't planning on buying the books yet, instructors advice. But after my 1st lesson :roll:. I've been reading the flightsim help :lol: and busy with RV's post...My gf keeps muttering "I've created a monster!" as she intro'd me to ML's :D
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Morph
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Postby Morph » Mon Nov 07, 2005 10:50 am

DieselFan wrote: How is this book different to the one I'll end up buying for my groundschool? Could I use this one instead? Cause at that price I can do it now!
This book is used here by at least one of the training schools as the manual. I know when I first did my course up in JHB there was no manual, or best some photostats. THis book is a nicely bound book, good for the collection. It covers everything except the specific airframes details for your type of plane and the Aviation Law, but you can get the SA Aviation Law book at any training school or from the pilot's supply stores at all the major airfields. Its a small red book, can't remember the price. Another one worth getting if you are going to the pilot's supply stores is the one used for your radio course, Yellow cover, it's the same one the PPL's use. I'll check on the exact names of these tonight and put them on.
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Postby Morph » Mon Nov 07, 2005 8:50 pm

The radio is..The Pilot's Radio Handbook - Seventh (or later) edition - Dietlind Lempp

The Red Book is - South African Airlaw for Private Pilots
Last edited by Morph on Wed Nov 30, 2005 4:08 pm, edited 1 time in total.
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VSI or Alt?

Postby DieselFan » Wed Nov 30, 2005 11:04 am

Sorry to bring this up agian, but I'm messed :? . I did stalls this morning and have had 4 different instructors. All say my level flight is fine, but today my Alt STAYS for atleast 5-10 secs perfectly on 6200' but the STUPID VSI goes -120' then -50' then -120 again and the alt doesn't budge? The trike is level and speed contant but with a slight crosswind.

I've been told that the VSI is near instant and the alt actually lags a few seconds behind? Previously I was told that digital VSI lags and analogue is better?!

So my question is am I keeping this thing steady or not and which gauge do I use VSI or Alt?! :?

I have sometimes noticed that the trike feels asif it's rising or dropping but alt stays the same within feet...

On closing one BIG shocker :shock: is how ones depth perception is messed whilst flying! Driving a car is easy you can see how far you are away, this morning I touched down when I thought I was 2m off the ground :oops: and again :oops: . So much for extreme low flying :(. Flight sim is easier :roll:
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Re: VSI or Alt?

Postby kb » Wed Nov 30, 2005 11:18 am

DieselFan wrote: So my question is am I keeping this thing steady or not and which gauge do I use VSI or Alt?!
Ok, so I don't have a VSI on the trike, but I know from the chopper, I only use the vsi as a quick reference. glance at it, and see if you are climbing / decending. then, use the ALT to balance out. In my PPL (H) trainging, my instructor had this funny habit of putting his foot / jacket etc over the instrument panel, to teach me now to judge (1000' AGL, climbing/decending etc). It was amazing, i have now stated to fly (the trike as well), without looking much at the instruments. They call it the "Seat of the Pants" feeling. when you are 10ft above the ground, you don't need no instruments to tell you if you are going up / down. Then again, at 1000 AGL, if you are decending at 1ft per min, is it going to make a huge change for you to correct it??? Same with the ASI, if the wind is not strong on my face, I get worried. Trying to fly more and more without instruments, what happens one day when you flying, and a bee or something blocks your pitot tube. Now your ASI reads buggerall, and you must land at some stage. Can you judge approach speeds without fixing on the instruments all the time. Maybe I'm getting sidetracked here (hectic X wind), but I feel that it's important to be able to "feel" what you and the plane is doing. If you want to fly instruments, have a look at the job applications section on flysaa.com. Just personal info, use it, don't use it.
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Postby DarkHelmet » Wed Nov 30, 2005 11:28 am

Ditto KB - I do seat of the pants flying - use instruments just as a reference and for radio altitude calls.
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Postby DieselFan » Wed Nov 30, 2005 12:04 pm

Well my instructor today gave me the impression he wanted me to "feel" the trike as when doing turns I wasn't allowed to look at the wing to see the angle, put I had to do 20 and 30 degree turns purely by looking ahead (I'll bring a protractor next time 8) ). I would also like to fly without instruments.

Here's something else I noticed, whilst parked the VSI was fluctuating between 10 and 20ft climb :roll:

kb you mention about being close to the ground...shees before I knew it I was on the bloody ground, I was pissed off for not seeing the ground so I ended up accelerating and creating a bouncing effect, grass air grass air. :evil: Obviously higher up this is unnoticeable.

Must say though Stalls are a RUSH :D. Perhaps a dumb question but after seeing how easy it is to recover from a stall in a trike, are there any risks of doing it more often? It feels wow.
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Postby kb » Wed Nov 30, 2005 12:15 pm

DieselFan wrote: Here's something else I noticed, whilst parked the VSI was fluctuating between 10 and 20ft climb :roll:
Aha, this might be the problem, which is confusing you. If the VSI is showing a clim when you are on the ground, then there are 3 possibilities.
1) Your eyes and brain need testing
2) We are in for one helluva big earthquake.
3) The VSI is unbalanced.
I thinkit is number 3. Park the trike, and turn the little screw (CAREFULLY!!) so that the VSI is on 0. This will then be more accurate. Otherwise, everytime you look at the VSI, you going to have to subtract 20 ft from the reading. Easy to do, but when you are juggling ATC's, radio, looking out for that other clown who is heading towards you, looking for a place to put down in the case of a engine out, wondering where you can land for breakfast, and also debating which bullsh!t excuse to use to the boss for why you late, you might just forget to do the maths, and subtract the 20.
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Postby Wart » Wed Nov 30, 2005 1:03 pm

"Seat of the pants" flying is a lot of what my instructor teaches.

1. Feel the wing flying before you apply bar pressure to take off
2. Feel the speed of the trike on landing rather than relying on the VSI

On turning, I was taught to watch the horison in front of you to judge your angle of turn; in the words of my instructor "Capture that visual image and use it to control whether you are going up, down and how steep your turns are"
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Morph
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Postby Morph » Wed Nov 30, 2005 4:27 pm

The VSI is way more sensitive than the ALT. It will tell you that your plane is climbing or dropping in feet per minute. Each line on the VSI indicates 100 fpm wheras on your ALT each number on the big hand indicates 100 feet and this is divided up into 5 small segments of 20 feet each. So at 100fpm climb your ALT will take 12 seconds to move one of the small increments.

Image


If you try to chase the VSI you'll end up bobbing up and down all the time. I only refer to the VSI on climb out, to see what I am getting, once flying level I use the VSI to trim the plane properly (3-axis), and then for setting up a glide approach or decent.
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