Got my License

[Tracer]

I'm not sure what the effect of a low QNH is, here in Gauteng. Maybe one of the guys can explain it to us?

[Lesser_spotted_owl]

Can thoroughly sympathise Tracer,

Took a week off last year to get some training in, couple of hours a day type thing, what happened? first time in 25 years that it snowed in Joeys!

When we did fly it was a bit crisp

[Wargames]

..... sorry QNH at 1012-1013, no good for flying..

Excuse a stupid question but why not????

I'm feeling a bit stupid as well.

thinking out loud - "Maybe it is the new instructor excuse for 'I had a bit too much to drink last night'"

What do you think??

[Tracer]

I have no doubt that there is a legitimate reason for this and I can only speculate, but I think that becuase of the low pressure the performace of the engine is even more degraded, than usual, up here. This coupled with the fact that the 2 of almost weigh 200 kg's, doesn't help.

I will however get the answer and let you guys know.

[Wargames]

Hi Tracer,

Don't want to hack your thread with technical stuff.

"Normal" atmospheric pressure is defined to be 1013.25 hPa.

I only said previous comment with tongue in cheek.

I'm sure there was a reason, just not the presure. Maybe a cold front, or a "head ache".

[Tracer]

don't sweat it, no offense taken.
I do however really want to know.

[Wargames]

Hi tracer,

Just remember that your instructor might have personal reasons not to fly. If he does not want to, see it as a day that flying is not posible. They are human to. Just enjoy the times that you fly.

a tip from my experience: You learn how to fly on the ground. Its almost like gholf. It is difficult to fix a bad swing on the course, you need to do that at driving range. Same with flying. Once you find your skills on the landing, its like riding a bike.

Enjoy it.

[Tracer]

Will keep that in mind.
Also, I have seen him very tired a couple of times and I can appreciate that he needs rest.
I'd rather fly when he is ready and I can learn something, otherwise I read books, ask questions and learn on the ground

[John Young]

I'm not sure what the effect of a low QNH is, here in Gauteng. Maybe one of the guys can explain it to us?

Hi Tracer,

You will still be taught about Density Altitude - "DA" which can be a killer , and

Hot, High & Humid.

In direct response to your question, use the calculator below. Take the altitude of your airfield and apply the variables. The "higher" your airfield equates to, the less lift, climb etc.

http://www.pilotfriend.com/calcs/calcul ... ensity.htm

By implication, I am not saying the conditions on "that day" were "not flyable" - just answering your question.

Regards
John ex-CIB

[Tracer]

Thanks John Young, that helped. Knew there was a good reason.

[Tracer]

Big smile on my face again today. Went cross country this morning, to Hartbeespoort dam. It was awesome, we saw a couple of balloons in the air and then a Tiger Moth. We circled one of the balloons, with the Tiger Moth below us . On the way back we saw another Microlight and a chopper.

It was great.

The wife went for a flip and she is also gonna start her pilot training...so as soon as she can think of a nickname, I will get her registered on the site.

[John Young]

...so as soon as she can think of a nickname, I will get her registered on the site.

Tracer's Handbrake could work

Regards
John ex-CIB

[DieselFan]

A QNH of 1013 in Jhb generally causes concern amongst microlighters. The NORM is around 1022 and winter 1027.

This results easily with a DA of over 8000 feet! The engines performance would be very poor and your 65hp 582 would have around 40-45hp. hmmm 503...

Depending on your weight and instructors weight I'd say it was a good call for him to CANCEL your training as not only your engine suffers but wing and prop too. It's a circle.

Bit more technical -

Your prop has less bite and needs to turn more to give same thrust but your engine has less power which means slower accelaration and less peak, in addition you will have to physically move faster to get airborn as your wing produces less lift at the same speed compared...as you can see it all compounds to general poor flying performance and when one looks at some aircraft's existing specs, downright dangerous.

- Much Longer runway
- Less lift (150fpm)
- Less power (30%)
- Faster take off and landing speed required

There must have been some undesirable weather system around.

When you look at the calculated numbers it gets scary quick. I know a few 3 axis pilots who wouldn't get out of bed, even to fly one up.

Lastly this isn't the first time I've heard instructors warning against low QNH, many instructors say you're looking for trouble flying with a QNH below 10 15 - in Jhb.

Ofcourse you can also phone SA MET, according to them, some days there's NO QNH predicted

Tracer, heed John Young's warning, it's bitten many many pilots ESPECIALLY here in Gauteng.

[Tracer]

Thanks DieselFan.

Believe me, if Flo says it's not safe to fly, I have no doubt in my mind that it's not safe. No reason to go out and push the envelope, endagering lives and aeries.

Can't wait for my next flight

I like Tracer's Handbrake

[mile high]

when is tracers handbrake starting training, did she enjoy her flip with flo. was she in the front seat?