All posts by Darcy

Smaller Squirrels

January 5, 2007Experimental, SightingGeorge ClarkDarcy

More from George Clark out in BC.

Now we’re going for the other extreme.

He is now experimenting with small Squirrels.

Darcy:
Here’s my latest, the Little Squirrel, and it’s a beauty. Wingspan – 10 in. Chord – 3.5 in. Total weight – 8.5 grams. The prop is 5 in., shaved down to save weight. Excellent wing loading of .24 g/ sq. in. Anything below .5 g/sq. in. will fly, but the lighter the better. I cut the wing from a single sheet of 3/32 contest balsa in order to save the added weight of glued joints, and gave it an airfoil shape. Test flights with a single short loop of 1/8 rubber prove that this little plane will disappear in a hurry unless care is taken to give it a large enough field to fly in.
Cheers
George

Pin It

Huge Squirrel from Surrey, BC

January 2, 2007Experimental, SightingGeorge ClarkDarcy

Here’s another stretched Squirrel picture from George in BC, Canada.

It’s interesting to see the different ways people experiment with the design parameters.

Darcy:

The first has a 4 in. chord and an 18 in. span. The prop is undersized –

6 in., and will be replaced with a 7.5 in. prop. Total weight 14 grams, for an excellent wing loading of .19 grams/sq. in. With two loops of 1/8 rubber it goes like a scalded cat, nearly vertically,

the too-small prop churning furiously. The second plane, the Giant

Squirrel, has a 36 in. span with a 4 in. chord. Total weight – 36 grams, for a very good .25 grams/sq. in. wing loading. It flies fairly well with a 9.5 in. prop, but I am going to substitute an 11 in. prop for better performance. This one is definitely for calm air flying as the wing is prone to flexing in windy conditions.

Cheers

George Clarke

Pin It

Hyper Squirrel — The largest Squirrel

December 10, 2006Experimental, SightingGeorge ClarkDarcy

I received these Squirrel pictures from George Clarke who lives in Surrey, BC.

I thought you might be interested in this version of your design. Wingspan – 36 in. Chord – 3 in. Length – 34 in. Weight – 36 grams. Not too bad with respect to wing loading – approximately .3 g/ sq. in. With 2 loops of 1/8 rubber powering a 15 in. carved balsa prop, it just pokes along with the prop turning fairly slowly. It will probably require a third and possibly a fourth loop of rubber to really make it go. I put a slight vee dihedral in the wing. Cheers, George

Pin It

Squirrels makes front cover of a magazine!

November 30, 2006Media, Outreach, TestimonialBrazilDarcy

Squirrel made front cover of Mecatronica magazine in Brazil.

A picture of the Squirrel apeared on the cover of the magazine.

In this page, they are adding the leading and trailing edge and then the center rib. The problem is that it will rarely fit properly this way. It’s better to put the three ribs down, then the trailing edge. When the trailing edge is put down we can easily make sure it connects to all three wing ribs.

Also, they’re using a square block to align the Winglets. This really isn’t necessary as a vertical angle is very easy to eyeball. Also when applying the tissue, there is a specific hand technique that reduces the breakages during building. Check out the “Make it” section for the official instructions.

It uses the old style motorstick which is thinner has a nose block. I discontinued that because with soft balsa there were a lot of breakages. They are also attaching the toothpick to the fin spar before attaching it to the model. The difficulty with that is that the builder will not glue it to both the motor stick AND the front of the fin spar.

Also, the wing seat is glued on top of the motor stick which is also a mistake. The original Squirrel used an 1/8th piece of wood which could be used to “thicken” the wing seat. The newer Squirrel uses a 16th thick piece that is glued to the SIDE of the motorstick. This gives a wider platform for the wing mount. The wing mount shown in the magazine will flip sideways when there is high torque from the elastic.

Overall the instructions are great because of the excellent pictures!

Here are a few pictures from some of the early workshops of the Squirrel here in Ottawa.

Pin It

Model Airplane Report

November 16, 2006Education, GalleryChuck YoungDarcy

This was sent in by Chuck Young.

Professor Emeritus (Geophysical Engineering)
Department of Geological and Mining Engineering and Sciences Michigan
Technological University Houghton, MI 49931 USA

Ken Fisher (about 83 years old!) working with students