The Morphocoupe gets flaps!

The Morphocoupe gets flaps!

The Morphocoupe started life as the 1927 Velie Monocoupe. After several rebuilds it has morphed into a high wing bush plane. And what does every Bush Plane need? That’s right – flaps!

It was a fairly simple addition – a couple of new flap panels cut into the wing. I added an extra tongue depressor to help strengthen the root of the wing.

Standard foam board hinges, but I reduced the bevel to the bare minimum - just enough to get a smear of hot glue onto the hinge surface. The hinges don't go beyond flush - just down.

9 gram servos, control horns, linkages and adjusters.

When I first built the wing I accidentally built-in some under camber. This meant the plane could fly quite slowly, but needed a lot of down elevator (or nose weight) to combat the lift at higher speeds. Slow was good, and worked well with the look of the plane, but it was a nuisance having to dial-in extra down elevator for faster flying – say for windier weather.

Adding flaps has allowed me to remove that under camber. In their new 'rest' position both the flaps and the ailerons are aligned 'flush' with the underside of the wing. This gives the wing a section very similar to the Baby Blender.

Long story short;

Flaps up – the plane needs to fly a little bit faster than it did before, but with much less of a tendency to pop the nose up when power is applied. In other words it performs more predictably over a wider speed envelope.

Flaps down – the plane actually flies slower than it did before. I made a guestimate for the down elevator mix needed to combat the extra lift created by the flaps, which has turned out about right. If I do push it too hard (faster than I really should with the flaps deployed), predictably it starts to climb and needs more down elevator correction to maintain level flight.

Regarding flight characteristics, this plane only flies bank-and-yank when it’s flying faster. This can be a bit disconcerting, especially if I’ve been flying a bank-and-yank plane just before putting this one in the air. In fact, when I bank this plane it often seems to want to keep going in a straight line. However, it is very responsive to the rudder, and flat or shallow banked turns are no problem.

I don’t know if this means the plane flies more ‘scale’ or true-to-life, but it does force me to keep working the rudder and ailerons – which must be a good thing.

Here's the plane in flight;