Practicing the impossible turn

[rwaltman]

At ~350 feet ...

http://www.youtube.com/watch?v=abUv_9YfHDY

Roberto.

Edit: PS: Thought it was obvious, but apparently it is not.
That's not me, not my Kitfox, not my video, yes my dream. :(

[SkySteve]

Nicely done Roberto. You make it look so easy and carefree.

[rwaltman]

Nicely done Roberto.

That's not me. [Wish it was...] I am still not flying, (waiting on a flaperon push-pull tube from Kitfox Aircraft and a few other annoyances.)

But I do taxi very well! See page 5 in http://proflyersinc.com/eaa501/propwash1210.pdf

Roberto.

[Dave S]

Roberto,

Less a matter of "the impossible turn" and more a matter of knowing the performance limits of the aircraft and pilot combination.

The advice to "land straight ahead" is solid for pilot/plane combinations where the pilot has never practiced turn arounds (practice at altitude) because if it is for real and a person tries the turn around, most really don't know what their plane will do; or, how to do it and they end up in the NTSB files.

Prior to my first flight in my kitfox, I was fortunate enough to spend a few hours in a similar Kitfox with an owner who had me practice (AT ALTITUDE!) turn arounds from a climbout configuration. Didn't take too long to get a 180 below 250 feet (Remember a turnaround to the runway isn't a 180....more like a 270). The owner could routinely get his Series 5 through a 180 in less than 200 feet..that was with full fuel and two on board.

The key to it is immediately putting the aircraft into a glide attitude, push the stick right away, and immediately roll into a medium turn (approx 45 degrees)....if the climbout speed was correct....the speed in the turnaround will remain a safe buffer above the stall speed. Climbing at 65 mph with the stall at 46 clean on my particular series 7 makes a safe turn with an immediate push and roll keeping the airspeed at 65 the whole way...with minimal altitude loss.

Now...to see what happens when a person mucks the maneuver up:eek:.....GO TO ALTITUDE...LOTS OF IT, go to a climb configuration, pull the throttle and do nothing for 3-5 seconds....or pull back on the stick a little...or try it with a shallow turn.... or a steep turn if you have had spin training........

Practice the maneuver to proficiency with 90, 180, 270, 360 etc turns... do it with and without flaps...you will know the difference between what is possible and what is not possible...the folks who become unfortunate statistics and have never practiced may be engaging in wishful thinking (better to just land straight ahead then) where real knowledge is needed in order to decide if it will work or not in a particular case.

The 4 most dangerous words in aviation...."I think I can"...

Great video:)...just forgive me for not practicing on the deck....I prefer lots of air under me in case I unintentionally mess it up.

There are a lot of airplanes that cannot do this as well as a Kitfox....

Great video,

Sincerely,

Dave S
KF7 Trigear
9142ULS Warp Drive

[SkySteve]

Roberto,
You are a taxiing maniac!!!!:D

[rwaltman]

... more a matter of knowing the performance limits of the aircraft and pilot combination.
Dave - Thanks for the thoughtful response. (Even though you are preaching to the choir.)
I don't know if you saw my reply + edit before - That video is not from me.
My plane's performance is completely unknown to me. When I get to fly it, (hopefully some time this century,) I will do a lot experiments *at altitude* to determine is flight characteristics. When I get to practice "The impossible turn" it will be in my own private imaginary field at 5000' AGL.

The 4 most dangerous words in aviation...."I think I can"... In particular when followed by "I thought I could, I thought I could, I though I could..."

Great video:)... Yea! - Now getting back to Advisory Circular 90-89A, "Amateur-built aircraft and ultralight flight testing handbook", and Vaughan Askue's "Fly testing homebuilt aircraft"

Roberto.

[TahoeTim]

For those with a Dynon glass panel (or other brand with audible warnings):

Before takeoff I set my altitude bug at 600 above the field altitude so it tells me when I hit my safe altitude for a turn back. I can do one at 400ft but I figure I need to add a little to account for the "surprise" factor.

Guys, try an engine out at 20 ft off the deck! on my low wing light sport, it loses speed quick so it's stick forward followed quickly by stick back and flare.

[Chewie]

Is best glide in a later-model kitfox the same as minimum sink? If not, aren't both equally important airspeeds to know? Kinda like Vy and Vx...

Mark

[cubtractor]

Always a good maneuver to practice(at altitude to start with of course) in any small airplane.

I can see my bald head talking to you rwaltman in one of the pictures of the fly-in. :D

[peanut]

I saw this video before the post. There is no question that there are balls involved, and a full understanding of this aircraft and physics. It's very fun to watch. 2:34 shows me how tough the gear is.. that looked like that could have ended a lot of fun right there.... Sideways gear hit? Very cool video, wish I had the balls for low, slow, steep bank turns.

[rogerh12]

Am I the only one that circles the airport after take off?
I don't worry about needing to turn back to the airport on low altitude engine failure because I am already turning back. After takeoff, unless it is specifically prohibited, after I reach the end of the runway, I turn and fly the pattern until I have gained some good altitude before I start flying to my destination. If anything goes wrong at less than 1000 agl, I am still next to the airport in the pattern. Ya, it makes the trip a little longer, but like they say, altitude is insurance and I always take out a little extra insurance before I head anywhere.
Roger

[peanut]

Am I the only one that circles the airport after take off?
I don't worry about needing to turn back to the airport on low altitude engine failure because I am already turning back. After takeoff, unless it is specifically prohibited, after I reach the end of the runway, I turn and fly the pattern until I have gained some good altitude before I start flying to my destination. If anything goes wrong at less than 1000 agl, I am still next to the airport in the pattern. Ya, it makes the trip a little longer, but like they say, altitude is insurance and I always take out a little extra insurance before I head anywhere.
Roger

I used to do that after a 100 hour inspection, oil change, gauges change, etc in the rental AC I fly. Now I just do my thing. I fly by all of the rules, and watch carefully and am ready for that open field at all times...

[TahoeTim]

roger,
what will you do if the engine dies between the time your wheels leave the runway and the end of the runway before you start your first turn? What do you do if you are in the crosswind leg? You are still 270 degrees from the runway!

IMHO there is a zone when it's too late to land straight ahead. Why not know that you can turn back? It's easy to practice at altitude using a road below you as the runway. 3000 agl provides plenty of altitude to practice.

something to think about...most crashes are in or near the pattern.

[szicree]

Don't forget that an idling engine and a dead engine produce significantly different amounts of thrust.

[rogerh12]

Steve;

If your engine does die, it’s best that the propeller breaks off too, from a drag prospective. That’s what happened in my Zenith 601, and I can say for a fact that the glide ratio was positively affected !!!!

Roger.

[rwaltman]

I can see my bald head talking to you ... :D

We can ask for a lower camera angle next time. ;)

Roberto.

[jtpitkin06]

I’m glad to see some discussion here on turning back to the airport. No problem with that as long as you know the aircraft performance and your own ability.

Just the other day a few of us airport bums were watching some of the local pilots take off and land with the usual, “Look at that idiot” comments. It brought up a lively discussion on which technique is better. For retractable airplanes, do you take off, suck the gear up and hold it low while going for speed; or, do you go for altitude leaving the gear down until there is no more runway to land on straight ahead? Is there any reason to do things differently with a fixed gear airplane?

We tended to agree that in the event of an engine failure in any airplane we would prefer speed over altitude. The consensus is avoiding stall is paramount and landing off airport is better than stalling in. Landing in a parking lot at 60 and sliding into a parked truck at 20 is deemed to be better than splatting short of the runway at 60.

A lot of the discussion bantered back and forth on when an engine is most likely to quit. The vote was unanimous for engine failures most likely at high climb angles. We cited reasons of:
Uncovering fuel tank ports with low fuel.
Unknown fuel pump failures that allowed the engine to run on the ground with gravity feed but not at high pitch.
Lower airspeed for less engine cooling resulting in a rapid engine temperature changes.
High power setting with low airflow cooling, leading to detonation

The reasons in favor of going for speed without an obstacle ahead were:
Greater pitch control with airspeed margins.
More time to react after the surprise event.
Most runways do not demand an obstacle climb.
Most runways are long enough for a GA airplane to land straight ahead or reach sufficient altitude to turn back.

Our informal panel of bums concluded it is almost always better to get to best rate of climb as quickly as possible. With best rate you have better glide speed available. When observing some pilots doing the angle climb vs the rate climb we noted time in steep climb angle was generally 12 seconds or less. At 1000 feet per minute, the airplane would reach about 200 feet agl where the pilots tended to lower the nose for more speed. Those pilots using a normal climb would also reach 200 feet AGL in the first 12 seconds without all the gyrations. So the altitude reached is about the same.


That brought up the next question: If best rate is good, is more speed even better? This generally applied to retractable aircraft where the pilot takes off, sucks the gear up, holds the airplane on the deck until reaching cruise climb speed and then zooms upward. At first we though that’s not such good idea. But we later considered the runway length. If you have lots of runway and no obstacle, why not go for speed with energy in the bank? Does the excess speed with the gear up make it impossible to land straight ahead on the runway? We agreed the excess speed might prevent a landing straight ahead on the runway, but so would too much altitude while still over the runway. The final opinion is that it’s about a wash… you either have enough runway or you don’t.

It was back in the 70’s when I lost a dear friend due to an engine failure on take off. As was his practice he would take off at a best angle for about two hundred feet and then accelerate to his best rate. His theory was that he was always practicing short field take offs and landings, so the habit kept him sharp.

On the fatal day he did his usual steep climb and the engine quit with the aircraft at high pitch and high angle of attack. Witnesses say he immediately shoved the nose down to get a glide established with the elevator clearly visible in the full down position. The nose continued to drop to about 30 degrees low. Just before impact the elevator was seen near full up. The aircraft failed to respond.

It is believed that the aircraft was near maximum angle of attack when the engine quit. With loss of power the aircraft entered a high drag situation either in a stall or very close to it. As the aircraft nose dropped, so did the flight path with the angle of attack remaining the same or possibly increasing. There was simply not enough altitude to recover.

I mentioned this during our discussion. We took this as a lesson learned and agreed that angle climbs in excess of the “50 foot” obstacle are probably unnecessary. Clear the power lines at best angle and go for best rate. If there are no obstacles, go for best rate right away.

It was a fun hangar flying session with all kinds of theory as opinions bounced off the walls. What did come out is that the “suck up the gear and go for speed” pilots may not be such idiots after all.


Have fun,

John Pitkin
Greenville, Texas

[MotReklaw]

Haven't tried it, but read where one pilot suggested that after lift off, moving parallel to the runway and climbing out at normal speed. Then, in case of engine failure, it is easier to turn 90, then 90 and be aligned with the runway rather than turning 90, then 90, then 90.

Is that so?

[Timberwolf]

MotReklaw, that's what I would sometimes do. However that was at my own strip at the farm where there were no other aircraft in the area. Otherwise I'd be leary at a civilian non towered that a cub without a radio may have entered the pattern and I'm headed right towards him. Chances may be slim to none that would happen, but may be something to take into consideration.

I typically take the approach of short field takeoffs and get the altitude below below me. Then climb out at Vx.