simurq
3rd Apr 2013, 11:30
Well, the more I delve into the topic, the more are chances to ask noob questions, as you can see if you follow up my posting statistics lately. :) So, please bear with me!
First things first... I'm writing a program which needs to calculate altitude of an aircraft at each checkpoint until it reaches the cruising altitude. Let's assume that a pilot chooses to climb at best rate-of-climb speed (Vy). And here is a sample scenario:
Airfield's pressure altitude (QNH) -> 1,500 ft
Distance to the 1st checkpoint (S) -> 10 nm
Airspeed taken from POH (Vy) -> 78 KIAS
Climb rate -> 1010 fpmNow, to find the altitude at next checkpoint I would simply do the following and wouldn't bother posting here:
Time to reach the checkpoint -> 10 nm / 78 KIAS = ~7.69 min
Altitude -> 1,500 ft + (1010 fpm x 7.69 min) = ~9,270 ftBut... for accuracy sake (http://williams.best.vwh.net/avform.htm#Mach), I need to know the ground speed (GS) of an aircraft which, in turn, depends on TAS derived from IAS using... altitude (!) as one of the variables. :confused: Looks like a chicken-and-egg problem to me, doesn't it!
Again, I could keep the calculations simple using the famous "2% increase per 1K of altitude" rule-of-thumb for the speed. But I need your help to explore all available methods to get rid of altitude-speed dependency before I move on.
So, I will highly appreciate any help!!! Thanks!
First things first... I'm writing a program which needs to calculate altitude of an aircraft at each checkpoint until it reaches the cruising altitude. Let's assume that a pilot chooses to climb at best rate-of-climb speed (Vy). And here is a sample scenario:
Airfield's pressure altitude (QNH) -> 1,500 ft
Distance to the 1st checkpoint (S) -> 10 nm
Airspeed taken from POH (Vy) -> 78 KIAS
Climb rate -> 1010 fpmNow, to find the altitude at next checkpoint I would simply do the following and wouldn't bother posting here:
Time to reach the checkpoint -> 10 nm / 78 KIAS = ~7.69 min
Altitude -> 1,500 ft + (1010 fpm x 7.69 min) = ~9,270 ftBut... for accuracy sake (http://williams.best.vwh.net/avform.htm#Mach), I need to know the ground speed (GS) of an aircraft which, in turn, depends on TAS derived from IAS using... altitude (!) as one of the variables. :confused: Looks like a chicken-and-egg problem to me, doesn't it!
Again, I could keep the calculations simple using the famous "2% increase per 1K of altitude" rule-of-thumb for the speed. But I need your help to explore all available methods to get rid of altitude-speed dependency before I move on.
So, I will highly appreciate any help!!! Thanks!