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# Flight Planning

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I have had ground school years back but still remember most of the stuff pretty well. I would like to be able to fill out a VFR flight plan form correctly without guessing. Figuring out (time = speed x distance) problems are easy but I am having trouble with the climb. I guess my ground school was not adapted for higher performance aircraft. Here in Indiana climbing from local airports to 4000 feet or so the performance will not change too much. Using a higher powered twin going from 4000msl to 14000msl climb rate can change quite a bit. How do I properly estimate using math. I have current winds aloft and winds at the surface. I can determine my initial climb rate from the POH charts but I know my performance will change over time. I do not know how to figure this out for each flight level in the winds aloft forcast because these charts are asking for density altitude. I am not sure how to figure out pressure altitude unless I am already at a altitude.Climbing at a constant speed, consistent power setting, something else has to change. Rate of climb and distance to top of climb.Climbing at a constant speed, consistent distance, and climb rate I will reach my top of climb at the same time but I will have to lower power output at lower altitudes and increase power output as I get to higher altitudes.I was told in ground school that you want to get up to higher altitudes as quick as you can comfortably to increase aircraft performance and safe fuel. Do you guys know of a good formula to estimate time off to top of climb.Tell me about decent too.I am probably just making this too complicated. I was just wondering if there was a way to figure it out instead of guessing or from previous knowledge. The aircraft I am using is a PA-30 from EaglesoftThanksWill

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Ok ahm, I'm not quite familiar with the PA-30 but I have flown a few PA-28s and -34s. Referring to the -34, I know there are charts for climb rate, for both engines and one engine out. Can't remember from the top of my mind if they go up to altitude though. I believe they did, but I will re-check in the POH, can do that earliest next week unfortunately.Anyways, if I understand correct you also want to know how to get pressure and/or density altitude.To get pressure altitude, you need to know current QNH. Basically pressure altitude is your altitude above 1013.25 hPa standard pressure (QNE). So first thing you need to know is how much QNH differs from QNE. Then you know every hPa equals around 30 feet of altitude (I was told 27' when you're really close to the ground, but since the value increases with altitude, 30' might be a good one to start with). So:Pressure Altitude = (1013 - QNH) * 30' + Indicated AltitudeExample, let's say QNH is quite low around 985 and your altimeter shows 16500 feet.1013 - 985 equals 28 hPa, which is about 840' (28 hPa * 30 ft/hPa). These add up to the 16500 on your altimeter, which is set to QNH 985. Sums up to ~17340 feet pressure altitude. Makes performance worse quite a bit. Is the PA-30 turbocharged? The PA-34 I used to fly was turbocharged and would usually climb at a pretty constant 1200-1400 fpm up to 10k', which is anyways the highest I went by that time. Didn't have the need to go higher (unfortunately!). :( Should double that next time and see how she does up there haha!Density altitude furthermore changes with deviations from standard temperature. Under ISA conditions temperature decreases 2

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I will read your post later. I have to go to a play with the girlfriend. I forgot that TAS will change because of temperature and pressure. The chart I have is titled multi-engine rate of climb vs density altitude and weight. It will give me the rate of climb for a certain point in time but will not give me a curve. You just can not follow the line up and say yup that is how it will be at this other altitude. Temperatures and pressures change along with wind. Will

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I would like to be able to fill out a VFR flight plan form correctly without guessing. I am probably just making this too complicated.
Oh maybe a touch. :-P But that can be a good thing... it shows you are thinking things thru and that is mostly what flying is about (or what is necessary imo). Measure it with a micrometer, mark it with a piece of chalk and cut it with an axe... sooner or later you realize what you need to be safe. And the time spent reasoning this out I feel is worthwhile.At Purdue we were taught a good guestimate is good enough for the Flight Plan (boy I hope I remember that correctly!). Remember, the time is for Flight Service to start making calls once you are 30 minutes overdue. ETE for a Warrior was ETE at Cruise point to point + 1 min/1000ft of Climb + 10 minutes for the approach + known delays etc...Looking at a PA-44 POH (Seminole) using the Performance Chart (Section 5) for Time/Fuel/Distance to Climb, climbing to a Density Altitude of 1 min/1000ft seems to be fairly close to 10.000' then say use 2 min/1000ft after that to 14.000'. There is a Performance Chart for Time/Fuel/Distance to Descend based on 2400rpm/165KIAS/500fpm gear up descent. From 14.000' @ 500fpm takes about, you guessed it, a half hour to descend. Distance is ~84nm / Fuel ~6gal.
I am not sure how to figure out pressure altitude unless I am already at a altitude.
Remember the "one inch per thousand feet." I believe this is valid to roughly 18.000'.So your Pressure Altitude = (Standard Pressure - Your Altimeter Setting) x 1000 + Field ElevationFor Example:P.A. @ Terry Airport / Indy Executive = (29.92 - 30.42) x 1000 + 922' (TYQ/Indy Executive Field Elev.) = 422' and you use this -500' difference as a "correction factor" to apply to the Pressure Altitude on the Performance Chart you are referencing.Also, if you have never owned a Pilot's Operating Handbook for any type of aircraft, and you do most of your flying in the Comanche, it might be worth spending the ~\$15-\$20 for a Comanche POH. Something to consider.

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