Vx and Vy - almost completely useless?

JasonC 23-Mar-14 20:53 #51
The challenge with my aircraft is that it will tell you it is ready to fly before you have enough rudder authority to counter torque.

Then it isn’t telling you it is ready to fly

Denopa, suggest you read what I said about inviting people to the airfield. And this big heavy aircraft is?

If it is described this way in our approved training manual it is appropriate. I didn’t write the manual and I didn’t approve it, but either I instruct according to this manual or I better look for another job.

Ah well, your problem, not mine. If you don’t feel strongly about what you are doing then don’t try to change it. I think I’ll stop poking you all with sticks and finish my wine before bedtime.

JasonC 23-Mar-14 20:53 #51
The challenge with my aircraft is that it will tell you it is ready to fly before you have enough rudder authority to counter torque.
Then it isn’t telling you it is ready to fly

But that is circular. It wants to fly at about 65 knots. If you let it the flight will be brief. I thought the whole idea of it telling you it is ready is seat of the pants stuff. No problem with that but just saying it isn’t a universal technique. I need to impose what is essentially a Vr on it at 85 knots.

Ah well, your problem, not mine.

It’s not a problem at all for me. There is always more than one way of doing things. I chose myself what I do. I could also instruct at a flying club instead of an ATPL school. And I would never say that the way flying instructors teach is “wrong”,

I don’t agree with the article. In part.

btw. he first argues that he has right to speak up because of his apparent bush flying experience but then continues with an article that is all about a Bonanza… that aircraft has useless bush performance!

Vx and Vy are very useful in day-to-day flying GA commercial. For example when flying through layers of cloud. Vx helps you to reach the top of that cumulus up ahead before you hit it. Vy helps you to reach the cloud tops quicker when they prohibit you from intercepting track.

As for Vr. I agree. Weight has to big an impact. Light or no payload means a GA aircraft is off the ground in 0-time. Heavy or max payload means you’re off the ground 10-15 knots later. Vr is never published for different weights as far as I am aware. Not in our aircraft. In our operations we assume take-off attitude as soon as possible and keep the aeroplane there until it lifts off. That is our method. The nose wheel is slightly above the ground.

In our operations we actually use a Vtoss (take-off safety speed) in the initial climb. This Vtoss is directly weight related, (different speeds for different weights), and is meant to give the best initial climb performance whilst giving enough control in the event of an engine failure. It is a number close to Vx.

Hmm. Unfortunately, you don’t mention what “your operation” is about. But unless you regularly have to deal with obstacles, flying any slower than Vy does not make any sense. Not performance-wise, not safety-wise and not cooling-wise.

I see plenty of mention about the aircraft telling you when it wants to fly.

But doesn’t that, to a reasonable extent, depend on where you’ve set the trim? Set it well back, and it will be trying to lift off much earlier than it will if you have it set neutral or somewhat forward.

Yes, that has certainly been my experience: on all microlights I flew during training, the elevator trim was marked with a “take-off” position. Which had to be double checked before take-off. On my own craft things are again easier: flaps full, trim full back, stick full back, aileron into the wind (if cross) then full power, steer along the centreline, and wait for the nosewheel to lift off.