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Archive for May, 2012
Posted by sir_clive | May 20, 2012 @ 04:16 PM | 7,413 Views
Things are moving...

I ditched the previous wing (it took me some tears to rip that spar out of the EPS) and made a new one, this time painfully taking care that the wire of my hot-wire cutter is as straight as possible.

I'm very happy with the result - good that I got rid of the old wing!

In the mean time, the laminating epoxy is ordered (Hobby King sells stuff from BSI, it should be very good), 48g GFK too, now I can only wait. There is enough to do anyway, I won't be bored.

I also ordered the servos from Giant Cod (now Giant Shark): Tower Pro MG90, cheap ones getting pretty good reviews, they should be here until the end of the week.

I was contemplating for a long time whether to put that polyhedral or whether to go with a flat wing. Finally, for practical reasons (position of ailerons / flaperons), I opted for a flat wing. Unfortunately, my main spar was already cut to 90cm flat wing segment of a (planned) polyhedral wing and glued in, so now I have to think of a way to connect it to the outer panels. This hobby seems to be a never ending series of bad decisions...

One thing bothers me a bit: the S6063 profile thins out into virtually NOTHING. The TE is so thin, the hot wire cutter melded way into the EPS, destroying some last 2-3cm. Even if it didn't, the last approx. 2cm would be thinner than the two 1mm balsa skin sheets. I decided to cut off the trailing (and badly cut) EPS part, glue a 3mm depron sheet instead and sand it down as thin as...Continue Reading
Posted by sir_clive | May 13, 2012 @ 05:47 PM | 7,843 Views
Looking for a slope soarer, I was pointed to this wonderful and easy to build plane designed by Springer:

This plane was designed to be a gentle soarer with motor to help her gain height, and as a such she performs beautifully!

However, the requirements on a sloper are a bit different. What I learned from talking to Springer, davereap and Don Stackhouse from DJAerotech (check, there is a GREAT information section in "Ask J & D", these guys build beautiful planes), there are a few important design considerations to follow when building for a slope. THANK YOU VERY MUCH guys, I learned (and am still learning) a lot from you!

The most important points are:

1. Stress / Load:

- Hang gliding in stronger winds impose rather high loads on the structure. Build the plane accordingly.
- Landing without a motor also sometimes turns out to be a pretty hard one. Make sure the fuse will survive it.

2. Visibility. On the slope, you can get pretty far in search for thermals. Interestingly, it's mainly the chord length and not that much the wing span which aids the visibility of a plane!

3. Wing thickness. Don't go over 7-8% of the chord length, that will induce high drag. I experienced it myself, sloping in some 30-40km/h winds with my Floater Jet - where other planes (real, dedicated slopers) were penetrating the wind as if it were nothing, my poor FJ hovered in place...Continue Reading