Building the MachNone
A Sky Pup Construction Project
I flew mine several times in fairly strong thermal conditions. It would make a good glider, has a very low sink rate, but the dihedral makes it yaw around a lot in response to changes in the air currents. You can get used it it.
Once I flew with a group of friends who wanted to get home, so we all took off at 2:00 PM with cotton ball thermals all around. It was not much fun.
Sometimes I thought it was going to roll on past 70 degrees but it never does due to the dihedral. It's weird though to be rolling into a turn while holding opposite rudder to no effect.
There isn't much problem in pitch because it is so stable in that mode. Not much danger of pitching up into a steep stall or going over the falls. The oscillations in roll and yaw are the only problems and more disturbing than dangerous.
There isn't any structural problems as long as you do not exceed the structural and manuver speed of about 52mph. When I flew home with my friends, I kept it slow knowing that the maximum possible gust could not overload the wing. It will stall first. Headwinds were 18mph and I landed in a crosswind. The landing was almost entirely on one wheel and the pup turned 90 degrees to the runway before coming to a stop.
The Pup would be a good for a soaring plane but there are negatives with the landing. If you are going to fly in good lifting conditions there is a potential problem with thermal gusting at the landing. Quick reactions to do a go-around and ample power to climb away from trouble are needed.
By the time I retired my Pup (in 1998) I was flying it almost any time of the day, and whenever my friends flew their challengers and kolbs. Only a serious crosswind landing at the destination would cause me to cancel the flight. It can fly and land in more wind than it can taxi.
Other factors limit it's usefulness in strong conditions.
The wing and airframe are fairly stiff compared to hang gliders, sailcloth wings or sailplanes. You will feel the bumps more. Secondly, major repairs needed due to landing in turbulence can be time consuming compared to sailcloth wings.
You can have a lot of fun in lift with the SkyPup.
Always go out later in the day when conditions are weakening. By the time you decide to land, the gusting will have subsided. You would be amazed how late in the day you can find lift. Pick areas of stone, gravel or concrete which hold their heat longer. Railroad tracks. Variometer not needed, but even a wrist altimeter is helpful.
Flying in Thermals & Windy Conditions