I realise that the post I'm quoting has been deleted since I started writing this reply (which is why I've left the attribution blank), but I think there are a couple of learning points that are worth keeping. So being a bit on the gobby side, I'm still posting the reply.
The event in question was a botched go-around, due IMO largely to a failure to brief properly on the part of the instructor, leading to an over-aggressive pitch up without the airspeed to sustain it. I wasn't there, so I can't say whether the instructor not taking over was a good or a bad judgement.
If you ended up just barely making it over the trees a couple of knots above the stall, what happened was this:
- You pitched up to a very high angle of attack that also generated a lot of drag (remember, the higher the AoA, the more drag, as well as the more lift).
- That drag stopped the aeroplane accelerating enough to achieve your normal climb speed.
- The engine/propeller had to overcome all that drag, as well as drive the aeroplane upwards. So less of the power from the engine was available for climbing.
- Therefore, even though the nose attitude would have been steeply up, the path through the air was in fact less steep than if you'd achieved Vx (speed for max angle).
- Hence the uncomfortable proximity to the tree tops.
A go-around, especially one that starts from very low speed and where a max performance climb is required, is not a trivial manoeuvre if the amount of space ahead is restricted. It's similar to a takeoff, starting from about lift-off speed but with two important differences:
- It's probably initiated with more flap (and hence more drag) than you'd want.
- It requires a greater pitch change than a takeoff - about twice as much
Therefore the pitch-up to achieve the transition from descending to climbing flight does need a deft touch - prompt enough to get the job done but still gradual enough not to generate too much AoA too soon with all the resulting drag, while smoothly applying power and probably raising the flaps a bit. Although doing all this currently feels like being a one-armed wallpaper-hanger in a gale, it will come with practice.
Hopefully this was all covered in detail in the debrief, and all is now clear. In retrospect, a good, if alarming lesson, but not one to repeat.
What I'll comment on is this:
I'm not sure if this is good practice, but I always aim for a couple of kts over both Vy and rotation speed now as a buffer.
It's not good practice.
Adding a couple of knots to Vy as a buffer against stalling is pointless, as Vy is already 20 kt or more above the stall. This is just slow(ish) flight, which you'll gain confidence with with practice.
If you really want to climb at max rate, fly at Vy. If you want to climb with a better view over the nose, to get a better ground speed, or to keep the cylinders cool, choose an airspeed higher than Vy, and fly that. If you want to climb at max angle, to clear an obstacle, climb at Vx.
Whatever you do, it should be intentional, and for a good reason.
Adding a buffer to your "rotation speed" is also wrong for a different reason. If the aircraft is moving fast enough to fly, get it off the ground. It will accelerate better in the air than on the ground, as you don't have the drag from the wheels, which on grass can be substantial.
Once off the ground, you have choices. You can hold the aircraft level, and accelerate in ground effect (look it up). Or you can pitch gradually to your desired airspeed, which might be Vx to get over some trees, or Vy or more as above. But
definitely not less than Vx, as your climb angle will always be worse than it could be.
Adding a buffer to your takeoff speed is also effectively
holding the nose down, in order to
not take off. In some aircraft (such as the Grumman AA5 series, among others), this is a Really Bad Idea, and it's really not a habit to get into. Crashing on take off with the engine performing perfectly is generally reckoned to be Very Bad Form.
If you have ambitions to fly well, the only habit to aim for is to fly the aeroplane correctly.
Applying bad technique to compensate for lack of current finesse is going to hinder you, not help you - the finesse will come anyway with practice, and then you'll need to unlearn those compensatory techniques. Or worse, fail to unlearn them
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