Takeoff technique

[raytoews]

I watched the new video of the Subsonex test flight. Really neat view from the pilots perspective. I noticed during the takeoff roll he seemed to pull the stick full back and as the nose came off he lowered the nose to takeoff attitude.
I know from watching videos that is the way carriers planes do it but they are being assisted rather strenuously.
I would think this would introduce drag from full up elevator deflection the same reason I don't lower flaps until just at rotation.
Is this a technique others use, is it unique to jets or to just this pilot.

Always something new,,,eh?

ray

[WLIU]

My off-the-cuff guess is that since the video is of a test flight, the pilot was checking and recording the speed at which the aircraft gained elevator control authority. Probably not "normal" technique.

Best of luck,

Wes

[Jetguy]

I watched the new video of the Subsonex test flight. Really neat view from the pilots perspective. I noticed during the takeoff roll he seemed to pull the stick full back and as the nose came off he lowered the nose to takeoff attitude.
I know from watching videos that is the way carriers planes do it but they are being assisted rather strenuously.
I would think this would introduce drag from full up elevator deflection the same reason I don't lower flaps until just at rotation.
Is this a technique others use, is it unique to jets or to just this pilot.

Always something new,,,eh?

ray

A lot of experimental airplanes do not have good shock absorption in the nose wheel or nose wheel strut.
In order to reduce maintenance and shimmy a modified soft field takeoff and landing is used on a regular bases. Pretty normal for most Vans tricycle gear airplanes. In light airplanes this doesn't effect the performance very much.

[Blue Chips]

That was (is perhaps) a common technique for military pilots, one I know of uses it in every aircraft, even a Challenger II. Have heard it called short field or maximum performance take off.

[Bob Dingley]

Ray, I watched that video and saw the same thing that you saw. Furthermore, it took me back a few decades to when I had an Aeronca 7AC. As I watched the video, I saw a classic Champ take off. The mighty A-65 just wouldn't accelerate the old girl in a tail low attitude. On the other hand, some planes that are fat with horsepower (BirdDog) can just blast off with the tailwheel on the ground.


I watched other Champ pilots use the same technique as mine. Accelerate tail up. Rotate and climb to five feet. Accelerate some more in ground effect. Climb out after you get 60/65 MPH. That little Hoover vacuum cleaner that the SubSonex wears on its back is not the most mighty engine around, but it does the job. There was a rule of thumb around for years that thrust equals horsepower around 375. At slow speed, not so much. AOA is important. Just my humble guess.


Bob

[jwzumwalt]

I watched the new video of the Subsonex test flight. Really neat view from the pilots perspective. I noticed during the takeoff roll he seemed to pull the stick full back and as the nose came off he lowered the nose to takeoff attitude.
I know from watching videos that is the way carriers planes do it but they are being assisted rather strenuously.
I would think this would introduce drag from full up elevator deflection the same reason I don't lower flaps until just at rotation.
Is this a technique others use, is it unique to jets or to just this pilot.

Always something new,,,eh?

ray

As any commercial or twin pilot will tell you, the "normal" takeoff requires familiarity with the aircraft.

You (the pilot) are expected to reach VR and know what back pressure is needed for the aircraft to rotate to a natural climb attitude. Of course all bets are off for other than "normal" takeoffs. The point of this is that a "professional" pilot with a familiar aircraft would not normally make very much adjustment after VR. One explanation for the video you cited was an early test flight might have warranted the pilot to hold the aircraft on the ground a little bit longer for a safety margin then "pop" the aircraft into ground effect until VY is reached. Gusting winds or a crosswind would have also warranted the pilot to do as you noted.

A normal takeoff (for me personally) in a single engine aircraft is to rotate at VR (just before or 1-2mph over VS) and lift off at VS +10%, accelerate to VX and then when prudent lower the nose to VY. The reason for this is to put the aircraft in VX as soon as possible which is also coincidentally the best L/D speed, so the aircraft is immediately in the emergency configuration during the upwind leg of the pattern. If something goes wrong no adjustment is needed to the airspeed.

There is no comparison to turbines and reciprocating engines because jets have an enormous amount of reserve /excess power - for example commercial airliners do not use a "normal" VR because they take into account a phenomenon known as inertial acceleration (due to excess power) and their VR is substantially lower than the VS stall speed.

[Byron J. Covey]

High thrust line.

[FlyingRon]

That's pretty much the standard short field procedure in many (conventional gear) aircraft.

[cub builder]

Keep in mind, the sub sonex has no prop blast over the tail, so pulling the stick full aft has little to no effect until it picks up some airspeed. Having a full deflection allows the pilot to feel the controls come to life as it picks up speed, then keep the nose light as it continues to accelerate.

-Cub Builder

[Frank Giger]

I usually keep a little back pressure in the Champ until I get some airspeed.

In the Nieuport I'm building it's also pretty common, as one has elevator authority long before one has it for the rudder, which can make for ground level aerobatics.

[Mike M]

control the aircraft. if the controls aren't effective, wait until they are. position the controls so that you will be able to tell when they become effective, then position them as needed to get the desired performance from the aircraft. any questions?

[Frank Giger]

Just one...why are you trying to mess up my Internet?

It's supposed to be a place where we all talk about stuff endlessly, particularly when there is a simple answer to the question.

[Bob Dingley]

Most of what I know about aviation was picked up before age 12. And that was by pedaling out to NAS Brunswick, ME. and watching planes. The SubSonex video kind of takes me back to watching the Banshees and Panthers take off. Their little turbojets gave it all they had and their take offs can be summed up simply: Drive the first mile of the trip, fly in ground effect for the second, then climb out at "high"speed. Every now and then, a Reserve F7F Tigercat would depart and show everone what "stump pulling" thrust is.


I'm not down on the SubSonex. Its a pretty nice ballance of fuel economy, safety and fun.


Bob