RE: Learning to use a hi-start
Some thoughts:
Get yourself a scale, typically a fish scale and see how much pull you are getting. Your Aspire probably weighs 2 to 2.5 pounds. So you want a pull on the hi-start of 6-12 pounds. What pull are you getting? A minimum of 3X the weight of the glider is needed and I usually launch at 4-5X the weight of the glider.
Are you launching into the wind? That is very important! Think of launching a kite with the wings being the kite. More verticle the wings the more resistance to the pull and the higher the climb.
150 feet of line on 50 feet of rubber seems a bit short. On 50 feet of rubber I would normally have about 200' of string, or 4 to one. And, when there is a good breeze, you might try adding another 50. But that assumes at least a 3X pull. But first get good with what you have before trying to add more line.
Tell us about the launch angle. You say you are launching it at around 45 degrees. That is OK, but you will get a higher launch if the plane is able to rottate into a steeper angle. say more like 60 or 75 degrees? When I launch one of my competition planes, the plane goes almost verticle, but don't strive for that till you become very good at launching. The steeper the climb angle the higher the launch.
You regulate the angle by the position of the hook in relation to the CG of the plane. The closer to the CG, the more it will rotate. Typically the hook should be around 1/4" to 3/8" in front of the CG. The further forward the more stable the launch, but you get less height. Closer to the CG, the plane will rotate more and climb higher but will be harder to control. On my competition planes the hook is almost at the CG and the plane goes almost verticle.
Think of the spike at the end of the hi-start as the center of a circle and you are standing on the perimiter of the circle. You are trying to get the plane to Travel along the edge of the circle as it launches. That will give you the maximum height. If the high-start is strong enough, and if you have some breeze to help, your plane should pick up all the string and the rubber at the top of the launch and the rubber will still have tension. You will need to dip the nose a little then pull up in order to get the hi-start to release. Doing this will also give a little "zoom" where the plane shoots up beyond the height of the hi-start.
That would be ideal Don't expect that right away. Work toward that ideal.
Does this make sense?