Change Forum... Civil Aviation Travel, Polls & Prefs Tech/Ops Aviation Hobby Aviation Photography Photography Feedback Trip Reports Military Av & Space Non-Aviation Site Related LIVE Chat My Starred Topics | Profile | New Topic | Forum Index | Help | Search
 Calculation Of Rate Of Climb
 Jetflyer From Netherlands, joined Aug 2009, 0 posts, RR: 0Posted Wed Mar 22 2006 00:30:19 UTC (9 years 1 week 1 day 20 hours ago) and read 10744 times:

 Hi, I have a project underway to calculate the rates of climb of airliners based on various factual information about the airfoil. This includes calculating the lift quantity and induced drag in pounds. Thew following data will go into a spreadsheet, you see, and these are the requirements: The input example below is of a generic aircraft. INPUT AIRFOIL Wing Area: 980sq/ft Mean Chord: 11.06ft Wing Span: 88.6ft Aspect Ratio: 8.01 Camber - %C: 4.05 Thickness - %crd: 9.25 OUTPUT REQUIRED Total lift at a given airspeed (lbs) at sea level Induced drag at a given airspeed (lbs) at sea level AIRCRAFT INPUT Gross takeoff weight: 107,456lbs Gross Thrust: 25,120lbs Parasite Drag OUTPUT desired: Some form of calculation that gives me the rate of climb based on the excess thrust/lift taking into account drag levels and aircraft weight. Is this asking too much maybe? I know there are many "experts" in this area on the board, so I'd be happy to know a way of calculating these parameters to give me some intelligible data on Microsoft Excel. That aircraft above is an example, with most of the data required to calculate this stuff, can anyone show me the formulas to create the lift/drag quantity and work out the rate of climb?
 Zeke From Hong Kong, joined Dec 2006, 9568 posts, RR: 76 Reply 1, posted Wed Mar 22 2006 02:42:24 UTC (9 years 1 week 1 day 18 hours ago) and read 10724 times:

 We are addicted to our thoughts. We cannot change anything if we cannot change our thinking – Santosh Kalwar
 Jetflyer From Netherlands, joined Aug 2009, 0 posts, RR: 0 Reply 2, posted Wed Mar 22 2006 11:48:50 UTC (9 years 1 week 1 day 9 hours ago) and read 10687 times:

 Thanks, I've been using that site as reference, but if only calculates the climb angle, for my aircraft I calculated that with 10,000lbs of excess thrust and a weight of 107456lbs the climb angle equals 5.33 degrees approximately. However, that doesn't tell me much, because it could be anything from 1fpm to 5,000fpm. I was told once that in order to climb the amount of excess thrust and lift in pounds put together had to exceed the aircraft's weight. Therefore I need to use those properties of the wing above to work out the rate it would climb at a 5.33 degree climb angle, based on a given airspeed and and a certain quota of lift based on aspect ratio, wing loading etc... There must be a way!
 David L From United Kingdom, joined May 1999, 9597 posts, RR: 42 Reply 3, posted Wed Mar 22 2006 12:43:17 UTC (9 years 1 week 1 day 8 hours ago) and read 10677 times:

 Quoting Jetflyer (Reply 2):Therefore I need to use those properties of the wing above to work out the rate it would climb at a 5.33 degree climb angle, based on a given airspeed

I'm not sure I follow. Are you saying the climb angle or the angle of attack (or something else) is 5.33o? If it's the angle at which the aircraft climbs and you have a given speed, wouldn't simple trigonometry give you the rate of climb?

Of course, as usual, I may be missing something.

 Vikkyvik From United States of America, joined Jul 2003, 10761 posts, RR: 26 Reply 4, posted Wed Mar 22 2006 13:17:16 UTC (9 years 1 week 1 day 8 hours ago) and read 10672 times:

 I think what you're missing is the property of the airfoil. Yes, chord, thickness, etc. are the physical properties, but to know the lift, you need to know the plot of lift coefficient vs. angle of attack. Once the lift coefficient is determined, you can calculate the total lift, and therefore, the induced drag. I don't believe you can calculate the lift just with the figures you gave, because you don't know what the incidence angle of the wing is in the first place. Unfortunately, many modern commercial airplanes tend not to use one airfoil over the whole wingspan. The airfoil will change as you go from fuselage to wingtip. God, it's been about 3 years since I went over this stuff, but if you need the formula for the lift or induced drag (both for a given lift coefficient), then I can supply those. ~Vik
 Do all philosophers have an "s" in them?
 David L From United Kingdom, joined May 1999, 9597 posts, RR: 42 Reply 5, posted Wed Mar 22 2006 13:29:45 UTC (9 years 1 week 1 day 7 hours ago) and read 10669 times:

 Yes, it's the "5.33o climb angle" that's confusing me. What exactly is "climb angle"?
 Jetflyer From Netherlands, joined Aug 2009, 0 posts, RR: 0 Reply 6, posted Wed Mar 22 2006 14:38:45 UTC (9 years 1 week 1 day 6 hours ago) and read 10661 times:

 Quoting David L (Reply 3): I'm not sure I follow. Are you saying the climb angle or the angle of attack (or something else) is 5.33o? If it's the angle at which the aircraft climbs and you have a given speed, wouldn't simple trigonometry give you the rate of climb?

No, you add the angle of attack to the angle of climb (5.33*) to get the attitude, but the point is that the angle of attack depends on the airspeed, which in turn affects the drag quantity which allowed me to calculate excess thrust in the first place.

The angle of climb is trigonometry it is implie that if the aircraft had excess thrust to match its weight it would climb straight up, but because its excess thrust is only a fraction of its weight, it climbs at a certain angle depending on that amount.

However, it doesn't tell me the lift produced by the airfoil.

The calculation of the climb angle was sin-1(10000/107456) = 5.339748767 degrees.

How do I go about determining the lift co-efficient? I used the NASA foil simulator to create the wing to those specifications, and it shows a lift calculation in pounds and a co-efficient. But I'm wondering how it calculates them.

[Edited 2006-03-22 14:42:16]

 David L From United Kingdom, joined May 1999, 9597 posts, RR: 42 Reply 7, posted Wed Mar 22 2006 14:52:00 UTC (9 years 1 week 1 day 6 hours ago) and read 10652 times:

OK. I'm crawling back into my box now!

 A3204eva From United Kingdom, joined Feb 2004, 1060 posts, RR: 5 Reply 8, posted Wed Mar 22 2006 22:14:26 UTC (9 years 1 week 23 hours ago) and read 10603 times:

 Well for the standard 3º climb/descent path it's groundspeed x5
 "They have lady pilots......... they're not that good, but they have 'em"
 Pihero From France, joined Jan 2005, 4799 posts, RR: 77 Reply 9, posted Wed Mar 22 2006 22:54:04 UTC (9 years 1 week 22 hours ago) and read 10594 times:

 Jetflyer, I don't think anybody on this site could help you if he/she wasn't a manufacturer's performance engineer. Vikkyvik started with a glimpse of some of the parameters you would need. Basically, a polar of the complete aircraft would be desirable and in all my years I haven't been able to procure one. The wing polar in itself is not enough. On the other hand, most posters here could provide you with the basic aerodynamic equations and the only way you could fill up that spreadsheet of yours would be to plot a lot of climb performance situations from an AOM, but it will only give you fleet average, not the accurate data you need. The same remark is also valid for engine performance : For instance, what is the thrust value of engine X at OAT = 35°c ? I have no idea, I only know that I could expect N1=98%....and so on. Sorry couldn't help you more
 Contrail designer
 Jetlagged From United Kingdom, joined Jan 2005, 2594 posts, RR: 25 Reply 10, posted Thu Mar 23 2006 09:23:11 UTC (9 years 1 week 11 hours ago) and read 10554 times:

 If you aren't accelerating, and you have a climb angle gamma, then Lift = Weight / cosine (gamma) Not exact, but close enough for your purposes I would have thought.
 The glass isn't half empty, or half full, it's twice as big as it needs to be.
 Doktor From Germany, joined Mar 2006, 29 posts, RR: 0 Reply 11, posted Thu Mar 23 2006 14:16:41 UTC (9 years 1 week 7 hours ago) and read 10528 times:

 Hi Jetflyer! If you are really interessted I could send you an pdf file from my lecture notes of flight mechanics. You can definitly find your answers, but they are not that easy to understand... Dok
 Jetflyer From Netherlands, joined Aug 2009, 0 posts, RR: 0 Reply 12, posted Thu Mar 23 2006 15:50:20 UTC (9 years 1 week 5 hours ago) and read 10517 times:

 Hi there, that would be interesting, I'll send you my E-mail address, or actually, it should be on my profile.
 Doktor From Germany, joined Mar 2006, 29 posts, RR: 0 Reply 13, posted Thu Mar 23 2006 20:15:14 UTC (9 years 1 week 1 hour ago) and read 10486 times:

 Jetflyer, I tried to send you a mail, but I couldn attach anything. You got to send an instant message or mail me your address!
 Liedetectors From United States of America, joined Jul 2005, 360 posts, RR: 0 Reply 14, posted Fri Mar 24 2006 00:21:56 UTC (9 years 6 days 20 hours ago) and read 10468 times:

 Hey Jetflyer, Any college level flight mechanics text book should be able to help. I would look at mine and help you out, but they are all at work.
 If it was said by us, then it must be true.
 Top Of Page Change Forum... Civil Aviation Travel, Polls & Prefs Tech/Ops Aviation Hobby Aviation Photography Photography Feedback Trip Reports Military Av & Space Non-Aviation Site Related LIVE Chat Forum Index

Reply To This Topic Calculation Of Rate Of Climb
• Tech/Ops related posts only!
• Not Tech/Ops related? Use the other forums
• No adverts of any kind. This includes web pages.
• No hostile language or criticizing of others.
• Do not post copyright protected material.
• Use relevant and describing topics.
• DETAILED RULES

 Similar topics: More similar topics...
Calculation Of Flight Times Between Destinations? posted Wed Mar 10 2010 16:48:23 by naritaflyer
Initial Climb Angle Of The Airbus A380 posted Tue Nov 3 2009 04:54:34 by Reggaebird
Rate Of Climb For 737, A310, AN-72 posted Sun Aug 17 2008 04:07:46 by SkyGazer
Calculation And Application Of Reverse Thrust posted Wed Oct 25 2006 03:05:10 by HighFlyer9790
Rate Of Climb: A333 Vs A343 posted Sun Jan 8 2006 19:58:41 by HT
Rate Of Climb Versus Angle Of Climb posted Wed Feb 23 2005 16:13:58 by Kiwiineurope
Rate Of Climb posted Sun Jun 6 2004 09:38:15 by KBUF737
Angle Of Attack In A Steady Climb posted Sun Dec 8 2002 04:57:19 by Zeke
Climb Of The B777/B744 posted Sun May 5 2002 08:57:47 by Mr.BA
Positive Rate Of Climb Or Run Out Of Runway posted Sun Aug 26 2001 17:11:52 by Western727