Trimming help

Ok so I've got my invader to glide lovely from a hand launch, long floaty glide, no hint of stalling but try it on my bungee (5 metres of elastic,6 metres of line) and kites like mad and pops off the line in a deep stall.obviously if it was radio controlled then I could overcome this with some down elevator..... any ideas? After 20 odd years away from the hobby my trimming skills are rusted solid:whistle

+1 for moving the hook forward.
If necessary move it forward so it only climbs slowly then start moving it back but the result gets progressively more sensitive. Even turbulence on the day can mean the hook position need to be adjusted. I seem to remember multiple hooks were used in the past.
Obviously with an elevator you have some control but it takes experience particularly when standing on the ground to get the best climb and not over stress the wings!
Come to that my first experience as a passenger in a full size winch launch was hair raising compared to the 'gentle' progress of an aerotow!

Thanks, I'll give it a go, the hook is currently 50% between the CoG and the nose despite the plan calling for it to be below the CoG although that is for towline use.
Time for a little surgery.....

Thinking about it some more I wonder if the elastic is too strong for the plane.
It sounds as if the elastic is initially over speeding the plane making it climb vertically and the elastic then rather too quickly runs out of "pull" leaving the glider to recover the best it can.
I am sure it is a case of a lot of try it and see but as with all 'ground fixed' take off methods the wind strength plays a major part.

Thanks, I did think that, had a few flights with my west wings Swallow today, I normally just hand launch it on a gentle slope but today I thought id try on the bungee, the hook on this model is as per the plan, inline with the wing leading edge, almost flew off the field!!!
Soooo what I've done is add a hook on the invader in approximately the same place, I'll let the epoxy dry and see if I can sneak out Wednesday and give it a go, that's providing these lovely mild calm conditions continue.
I know this goes against the advice you gents have given but to be honest moving the hook back is a darn sight easier plus I thought (probably wrongly) that with the pull nearer the CoG it may accelerate slower as the force would be directed down to a certain degree .....please feel free to shoot me down in flames if I'm talking nonsense.

Paul
What you have to do is remember that the CofG is a 'point' somewhere inside the fuselage. The centre of lift (CofL) is another imaginary point that in a stable plane is just a bit behind of the CofG.
Now imagine the 'line' of the tow line extended past the hook, would it pass above or below the CofG and CofL points?
At the point of launch with the hook fixed to the underside of the fuselage the tow line will tend to raise the nose. The nose of the plane will continue to rise until the line of the tow moves in front of the CofL. Of course as the plane climbs the line of the tow changes moving further ahead of the CofL so it progressively pulls the nose down.
If the hook is too far back the line of the tow once the plane is climbing means it will to increase the angle of climb to over 90 degrees at which point the line slips off hook or the wings simply fold!
Particularly with bungee in the line much safer to start with the hook well forward and move it gradually back.

I get your point, told you I was rusty! Think I'll add another hook well forward before the epoxy sets!!!!

Up early this morning to be greeted by a almost flat calm...time for a few quick test flights.
after our discussion the other day I did add a hook further forward as well as one further back.
first launch on the foremost hook was terrible, went up the line at a horrible angle, second flight on the rear most hook....success!!! went up dead flat and pinged off the line right above the stake followed by a lovely floaty glide, really really must fit a d/t, even in the cold damp air this morning ( 7am)it hung in the air. photo below shows the 3 hook portions.

Sorry Paul, you duplicated your last post so I deleted one of them, for some reason the picture has gone from this one now.
Can you post the picture again please?

Pol.

oops! sorry about that, posted using my phone....let's try again...