Learning to fly, or thinking of learning? Post your questions, comments and experiences here

Moderator: AndyR

By iantruckers
#1855808
Hi! I've had 3 1/2 Hours of flying lessons now (Love it!!!!) but I'm getting stuck into the theory, I've got stuck AGAIN, I'm going in for my LAPL due to my age & will never use it for a career & come across a section in my book explaining MACH speeds, speed of sound @ 15* @ MSL = 761mls/hr 661kts/hr, do I need to be able to calculate part MACH speeds @ the speeds that I'll be flying at for the LAPL, 100kts (MACH 0.15 I think & MSL 15*)? Also, how do you use the Jeppesen CR3 to calculate MACH speeds? There's a section of it showing MACH speeds but they just don't make sense, obviously something to do with CAS & Temperature, Cheers, Ian
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By FlightDek
FLYER Club Member  FLYER Club Member
#1855813
Don't worry about it - you only need to know that sort of stuff if you do a CPL or ATPL
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By Morten
FLYER Club Member  FLYER Club Member
#1855816
Funny how some undergraduate stuff never leaves my head.
the speed of sound a in m/s is the square root of the product of gamma, R and T.
Gamma is the ratio of specific heats for air and does not change until you get into hypersonic ranges - it's 1.404 at ISO or thereabouts
R is the gas constant which for air is 287 (I cannot for the life of me remember the units of that)
T is the temperature in Kelvin

T will change with the weather but also with altitude.
R is constant for a given gas but as you go up through the atmosphere, the composition of air changes so R change as well. But at our puddlejumper levels below the troposphere, R is constant.

So T is the only practical variable.
At sea level ISO conditions of 15°C = 288K, a works out to be 340 m/s. Convert to mph, kts or whatever you want from that.
My guess is that on your C3 slide rule, you set a datum on the temperature and read off the M number against a TAS. You may need to find the TAS from the IAS using another part of the rule before that.

Need to know for LAPL? I doubt it, I don't remember it being part of the syllabus for the PPL.
But knowing it makes for great conversation around the dinner table ;)
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By T6Harvard
FLYER Club Member  FLYER Club Member
#1855821
@iantruckers are you going to post about each lesson, as some of us are doing?
Glad you are loving it!!
Where are you training?

I'm at the 'frustrated by my lack of ability' stage but hope that will pass, or at least move on to the next bit of the training :lol:
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By JAFO
#1855835
T6Harvard wrote:I'm at the 'frustrated by my lack of ability' stage...


Many of us are still at that stage 30 odd years later, so it isn't a problem.

Good luck with the rest of your lessons.

@Morten - sounds fascinating, I am only sorry that I can't join you for dinner to discuss it further.
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By iantruckers
#1855914
Hi! I`ll certainly keep you updated as to my progress (or relapse) , I`m training at Barton in Manchester with an absolutely brilliant trainer, Ted, He really does explain everything like the consequenses of too little or too much input to a control. I've just learned level & turning flight. I had a voucher given to me for Christmas & used that last Sunday at Blackpool, the instructor was Raja where he asked me what I'd like to do as the voucher was for an hour trial flight so I asked him if we could just go and fly level & turning flight seeing that Ted had taught me that. We had a brilliant time, we flew up as far as Kendal & Lake Windermere. I just can't wait to get up again. Ian
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By iantruckers
#1855915
Someone on this website told me some VERY wise words & I`ve taken this to heart, he said "even if you don't achieve your license by 30hours, you`re actually flying so don't look at training as a chore, You`re flying". Ian
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By iantruckers
#1855936
Hi T6Harvard, Ted's always saying "It will come with time", he`s absolutely right, when he told me that when turning, I had to add Rudder & Elevators, I couldn't get my head around it but now I find it easy, it's just Newtons 3rd law of Physics, because you`re turning, the earth is now pulling you down at a different angle through the down wing, not the floor of the aircraft, due to turning, there is less lift and you`re being pulled into the turn, hence rudder & stick with ailerons, Easy. Ian
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By ROG
#1858251
According to flight radar 24 our cherokee 180 hit 490 knots last week.
We"re hoping to hit mach 1 next week.