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StraightEdge

The Next Level... Launch Technique?

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Richard Swindells

10 years old.. But still relevant launch slomos of UK pilots 

 

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Neil Harrison

Olaf Starmanns demonstrates the LAG beautifully here.

Notice that the hips are almost 90 degrees to the target line (belt buckle facing target) and the rest of the body is unwinding.

See where the model is right behind him, lots of potential energy stored here for a fast and powerful release.

 

F7CB8C92-DB9D-409E-B866-C7B62209232D.png

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StraightEdge

Neil, that's really clear.

What's the norm with the momentary switch?  Do people hit it briefly on release, or hold it in throughout the body rotation?  I've been pressing it momentarily for pitch-up, which is another thing to think about and get the timing right.

And how long is zoom-mode normally timed for?  Mine is fixed at 2secs from release of button (no ability to alter the sequencer variables on my TX).  What difference would 2.5 or 3secs make in practice?

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Paul Gleeson

I have mine set at 3 secs. I can judge my launch height farewell by when I have to push over at the top and when the zoom mode ends.  

I made a table of time vs. launch height (ignoring the drag of the model , and the point at which you release the launch preset) The difference between a 44m launch and I 50m launch is just 0.2 secs.

Oh this is just a theory.  Converting kinetic energy at the ground to potential energy at the top.

Gravity constant x height = velocity squared / 2

Interesting.....

launchHeight.png

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mikef

I think most people hold the preset for the pitch-up in throughout the launch sequence.  The preset is released 'a moment' after launch.  The duration of 'a moment' depends on your instinct.  It's like a gymnastic manoeuvre -you try it it and if it's not right you change it - it can't be defined really.

My approach is to ‘do the same thing every time’ timing-wise and alter the amount of pitch-up trim change to get the pitch up I want.  That way I can  keep a common launch pattern if I change models.  I just launch them all in the same way and trim each one  to suit my launch timing.

I use one flight phase for pitch-up and another for the straight up climb.  Given that my Tx makes the change between flight phases over a finite time, I think I release my momentary pitch up widget on launch.

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SilentPilot

What is this 'zoom' mode that you speak of?

I get the up elevator on the push button. Then release when climbing but what is this 'zoom'?

Do you have it in a certain mode for a few seconds after release then it automatically swaps to cruise?

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Paul Gleeson

I have the launch preset with the button held down. This is "launch" mode. It overrides all other flight modes, therefore will retract flaps etc.

I hold the button down before I begin the launch spin. Therefore only one thing to judge, when to release the launch button, at the angle I want to climb.

When I release this button, another flight mode "zoom" is immediately engaged, which sets some reflex on the wing for minimum drag and elevator trim to keep the climb straight.

After 3 secs the "zoom" mode is cancelled automatically and then one of the normal flight modes (speed, cruise, thermal) is engaged depending on a switch setting.

If I was in landing mode with flaps down, the 3 secs gives me enough time to get the flaps up to ensure I am in a normal flight mode,

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mikef

As Paul has said, the zoom mode is for a straight, 'ballistic', climb with the model in a minimum drag configuration, neither pitching up or down.  (Incidentally, Free Flight glider flyers call this part of the launch the 'up ballistic' phase.  They do it with a pre-programmed set of instructions to move the surfaces.)

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thechalster

Speak to crasher..,,, he has got the down ballistic phase well sorted. 😀😀😀 

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cirrusRC

I exit zoom automatically  when I push over, based on amount of elevator input detected.  I'd rather be in control vs a fixed time period.

Pierre has awesome technique - coiling like a spring.  That said everyone has different biomechanics, some are more naturally gifted than others.

What works for one person might not be exactly right for another.

There is a nice video of Jeremy Andre launching to 79 meters.  Huge backswing with insane arm speed and power.

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Paul Gleeson

Can you share the video link?

Hmm.. switch based on elevator input might be a nice idea. Have to think how I can manager that on a DX9, and keeping all the feature on my current method.

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PaulR
1 hour ago, Paul Gleeson said:

Can you share the video link?

This might be the one being referred to, from his Facebook page: 

https://touch.facebook.com/story.php?story_fbid=10216036370414916&id=1618580627&anchor_composer=false

Most of the Taranis DLG programs have the zoom mode deactivated by elevator input. It never occurred to me that those with "lesser" transmitters would have to use a timer 🙂

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Neil Harrison

Taranis, the best £160 you will ever spend!

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Simon B

Does any one have the "escape" velocity or outer wing tip speed of a good launch? 

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Whitmore

The coiled spring analogy was really brought home to me from watching Jun Cats - he seems to put so little effort in :)

 

 

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Paul Gleeson
9 hours ago, Simon B said:

Does any one have the "escape" velocity or outer wing tip speed of a good launch? 

Have a look at the table a few posts back. 

 

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Simon B

That was what got me thinking, about speed and diameter, and how keeping it low might increase ones bollas length for a given axial speed to ones advantage, I thought about the numbers and realised I had more grasp of the physics than the math.... non linear acceleration...

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mikef
15 hours ago, Simon B said:

Does any one have the "escape" velocity or outer wing tip speed of a good launch? 

Paul's table gives us the time it would take for the initial vertical speed of a drag-less model to slow down to zero under gravity (a vertical stall)

My estimate for a top class launch speed is around 40m/s  - more or less the highest speed in Paul's table.  My speed is based on video analysis.

Any rotation of the model at release would change this figure  for the outer wing tip which a first guess could be about  half as much again.

In reality, I think the 40 m/s launch would give more like 60m launch height due to losses.

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Paul Gleeson

CofG of the model will be at approx. 175cm (100cm arm + 75cm half span)

Therefore the outside tip will be 250cm (arm + span)

So it will be going 1.42 times as fast (250/175) 

40m/s at the CofG means 57m/s at the tip (over 200km/h)

(if my maths is right?)

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Neil Harrison

This will be a great subject to discus and share ideas at the first event of the season....’come try it’ at buckminster lodge

We are hoping for a good turnout..

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