Monday, August 04, 2014

We Just Don't Always Use It

A fueller once told me that he loved watching me take off because the shallow climb angle is different from the way the other aircraft at that airport behave. He thinks it looks cool. Interesting.

Almost all the traffic there besides me are training aircraft, light singles flown by students. Having worked as a flight instructor, I know that such aircraft are also usually close to max weight with an instructor on board. Students tend to rotate late and lift the nose wheel higher, thinking they are pulling the airplane off the runway with their own strength. The manufacturers recommend climbing at the best rate of climb speed, which makes sense because if the one and only engine fails, the more altitude the better. They're only going to climb to three or four thousand feet above ground level anyway, so that's reasonable for them. they are climbing at 500' to 700' per minute, maybe less if it's hot.

Most of my takeoffs are within two percent of max take off weight. At rotation speed I lift the nosewheel just enough to have it clear of the runway, with no attempt to haul the entire airplane off the ground. I know that will come. At that point I am waiting for the speed to come up to blue line, the single engine best rate of climb speed. That happens just before I run out of runway, and then I raise the gear. When both engines are functioning, there is no reason to climb at as low a speed as single-engine best rate. There are no obstacles or noise abatement areas off the end of the runway, so I don't use the two-engine best angle of climb speed. I could climb at the two-engine best rate of climb speed, but the manufacturer recommends a speed fifteen to twenty knots faster than that. I know that I can reduce power slightly, and then climb at the manufacture's recommended climb speed for thirty minutes without overtemping anything. So that's what I do. I stay low over the runway, get my speed, ensure the airplane is flying properly and then climb away at a sustainable rate. I'm climbing at around 750' per minute, but because I'm doing so at around twice the forward speed of the little guys, this translates to a lower climb gradient. I guess it looks cool because it's the way heavies take off.

Obviously if there is terrain, or IFR climb gradients in excess of my default climb rate, then I'm leaving take off power set and climbing at the angle required to meet safety and regulatory requirements. And if I'm on a test flight or empty for some other reason, then my take off profile might be a little different. It's never like the one at the beginning of this video, though.

The second take off in the video, with the immediate left bank, is pretty common for me, when I'm at an airport served by large jets. ATC wants me out the way, fast, so they clear me to make a left (or right, but the most recent one was left) turn as soon as safely able. As soon as have stable control of the airplane, I bank and turn myself out of the path of the Boeing or Airbus that ATC will clear to take off as soon as they are content that I am clear. The other day I saw a Boeing 737 doing a fairly steep low level turn. It was a bright sunny day and I guess they didn't want to go way the heck west to intercept the ILS.

Airplanes are way cool.


RTD8450 said...

You said it Aviatrix - airplanes ARE cool! It's also too bad that (to presumably prevent less capable craft from trying the same) Farnborough ATC asked Boeing to not do that demo on the second day... spoil sports.
BTW, and I also presume it has been noted in other earlier posts of yours, what type of a/c do you "normally" fly?

AndrewB said...

I live a couple of miles from Farnborough and visited the show on the Sunday this year. There were lots of surprising acrobatics, but unfortunately did not see the Dreamliner do this.

The Airbus 380 and 400 were very impressive, but for me the real star of the show had to be the Vulcan. The roar was unique. Shame this is likely to be the last year that it flies.

Aluwings said...

The credits make it clear that this was an actual aerial sequence. But the way the video was processed made it look a lot (at times) like a video taken within a flight sim program like x-plane.

I was thinking that an x-plane sim would be a great (low cost) way to script out the initial plan...