Discussion in 'The light stuff area' started by ryanjames170, Oct 3, 2018.
What's the good bad and ugly of it?
I've heard they have a reasonably good safety record. The plans seem quite thorough, and are supposed to have been drawn by some engineers from Cessna. Sky Pups are supposed to come out at 190 lbs empty, but I seem to recall from discussion groups that they usually come out heavier. Controls are only rudder, elevator, and throttle. They're intended for relatively low power. As I recall, the instructions say no more than 20 hp, though I think sometimes people use a bit more. I recall you're not supposed to have more than 60 lbs or so for the engine, prop, redrive etc. It does have some AN hardware and some welded bits, but in general the materials are fairly basic. For instance, you're supposed to cover it in dress lining! Mostly it's wood and Styrofoam insulation that you can get at lumber places. The wheels are from BMX bikes! If I recall correctly, the gross is supposed to be 400 lbs. The fuselage isn't all that wide, either, so if you're big and/or heavy, you may have a problem. The wings are in 3 pieces, with the center section permanently attached.
You can find lots more at machnone.com
I don't recall any weldments on the plans and can't imagine where they could be other than on the control stick, but otherwise that describes the Sky Pup pretty well. It's been a long time since I had my plans out but IIRC the build manual has you size the fuselage to yourself in a pretty clever way. Really the whole thing is full of clever and cute solutions to cut weight and complexity, it's clear that whoever designed it wasn't copying anyone else's work. For example, it has sewn fabric hinges on the control surfaces and the belly has a hole that zips open so you can step right through when getting in and out since they felt reinforcing the floor to take that strain was unnecessary weight. The landing gear is a single leaf wood spring.
The only negative I can think of is there are not more of them.
Designed by an engineer. Easily made the Part 103 wt limit. Flew well on very little power, easy and inexpensive to build, even by today's standards. Steve Wood knew what he was doing.
The Sky Pup was designed by a Cessna Aircraft engineer, and is known to be a pretty good design. Definitely not a "back-yard hillbilly" design. Much more refined and engineered.
It is a two-axis control aircraft, and it has been discussed here on HBA that the wing structure may not be suitable for a simple conversion to 3 axis.
An interesting and well thought-out design. But some of the compromises or design decisions made on that aircraft will not suit some builders.
If you have good google skills, there are picture on the interweb of a Skypup modified by it's builder to a low wing configuration. That plane may have ailerons, I don't recall.
The Sky Pup is an elegant and efficient design from a time when most other ultralights lived up the "flying lawn chair" nickname. The two-axis system has its pros and cons but it is well-proven and easy to build. If you need ailerons then build something else. Note that the Sky Pup does use a conventional stick and pedals (actually a rudder bar) but the stick only moves fore and aft since there are no ailerons.
Dan Grunloh is a well-know ultralight/microlight pilot who has written for EAA's Experimenter and Sport Aviation. He built a Sky Pup in the mid-1980s and was the Sky Pup newsletter editor for many years. He wrote this to sum up his thoughts on the Sky Pup.
You will find more articles by Dan and others on http://machnone.com and several experienced Sky Pup builders and pilots participating in https://groups.yahoo.com/neo/groups/Skypup-club/info.
The biggest shortcoming of the 'Pup is that it's just too light for most pilots at 195 lb/400 lb. Most homebuilts come out heavier than the prototype, so once you've added fuel, there's not much left for anyone but a light and trim pilot. A "Sky Pup XL" at 250 lb empty/500 lb gross (or even 300 lb empty/600 lb gross outside Part 103) using a modern paramotor engine and perhaps with tricycle gear would be an absolute hoot.
Oops. A quick review of the plans seems to indicate you're right about the lack of welding. But it looks like I can't edit my post.
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