susquach

My Feedback: (1)

Would really apprciate any suggestions on how to increase the energy in a 2m up-start. Here's the problem: I'm currently using a light duty up-start (Dynaflight) to launch a 60" HLG and am VERY happy with the way it handles the little plane. However, it is very marginal when launching my (unfortunatly porky) Gnome 2m. I'd really like dimesions of the rig and the smooth release of energy provided by the original rig...and want to preserve that as much as possible......just add a little more umph to get that 2m over the top and released at an acceptable height. Am considering adding a 8' length of 1/4" bungee that can be clipped into the Up-start for 2-meter launches. Any suggestion will be appreciated.

BTW, while at a sporting goods store I noticed a product intended to launch fishing tackle...sort of a slingshot made from 1/16" x 7/16" x 15' rubberband material. Seems like that material might add some energy while retaining the stretchy character of the surgical tubing. Has anyone tried this stuff?

da Rock

Mixing rubber can give you fits. If the lighter stuff can't stand up to the additional pull after it reaches max extension, you ruin it.

Also, bungee stretch isn't much compared to highstart rubber. So you do get initial pull, and lots of it, but it's lots harder to control during the launch. You wind up with lots of power right off your throw, right when it upsets the launch the most.

I'd make up a pure bungee and go from there first. They're different animals than up-starts, and hybrids aren't easy to do.

susquach

My Feedback: (1)

I understand what you are saying. The selection of rubber material/ size of model is really important for best operation. Think the answer to the problem is to match as closely as possible the character of the original latex tubing.

aeajr

My Feedback: (2)

You need more pull! Get a more powerful hi-start for your 2M plane

As I recall, we tested a new Dynaflite standard and it gave about 6-8 pounds of pull. The Dynaflite HD will go to about 10 or 12. I seem to recall we tested a NESail Standard to 14 or 15 pounds, but am not sure. This was several years ago, so I am not certain of the numbers

As a test, take the rubber and double it. Reduce the sting by 50% and see how the launch goes at 300% pull ( now half the length remember). Do you get a better take-off? Do you pull up more of the string?

YOu want a pull for 4-6X the weight of your plane. If your Gnome is 40 ounces/2.5 pounds, then you want at least 10 pounds of pull and it will likely take 12 with no problem. I launch my Spirit at 12-14 pounds.

Also, try taking some weight out of the nose of the plane. It may fly better and it may launch better.

Where is your tow hook located? It should be about 1/4" in front of the CG.

Are you adding any up elevator on your launches? If balance and hook location are right, you should not need any.