Replacing and upgrading my Miles M20.

First built March April 2010. Wing span about 19.5 inches weight ready to fly
is 4.8 ounces. It is equiped with a 10 gram motor, a 6amp esc, 2 5 gram
servos on elevator and ailerons. The construction was simple a taco shell
formed fuselage and an undercambered wing of two layers.

I've been happy with how it flies. But now it is a little beat up and I think I
can build it perhaps a little better.

So I am leaving the size alone. But changing other things. First off I've
changed the wing. Last time I used under camber and polyhedral. This time I
started thinking I would make a Jedelsky style airfoil. Looking at the 3 views
and reading I finally noticed that the original had a thick airfoil. So I
decided to make something mostly symmetrical but thick maybe close to scale. I
also noticed that if I copied the taper shown in the three views I would end up
with something sort of like polyhedral.

Interesting plane. Faster than a Hurricane, slower than a Spitfire and longer range and more ammo than either.
I'll be watching with interest. Good luck with it all.

What foam are you using?

Depron, it is about 1/16th thick. The sheets I have are about 9 and 3/4 by 36.
They flex easily in the long direction. That has worked out well for the wings.
I did score some lines on the back side of the leading edge to help influence
the foam to bend evenly at the leading edge. I also put some blue masking tape
on the outside of that bend to keep the foam from cracking. I made the bend by
rubbing the foam over the edge of my counter and rolling it over a rod.


I have been fascinated by the history of the Miles Aircraft company. There is
this fighter, the Libellula, the M.52, Mr. Miles produced some of the more
interesting designs of the period.

Since I am making a radical change to the wing I did a little glide testing.
For that I made a taco shaped fuse and tail feathers of the correct size.

I had to make an adjustable wing saddle, taped on as you can see in the photo.
One thing learned was that I did not want to leave the trailing edge drooping
down like you see in the photos above. That acted too much like full down
flaps, and was no real surprise.

I was surprised at the wing incidence. What I thought was level turned out to
be quite positive. I ended up lowering the leading edge close to a quarter
inch. (Note I am sticking with inches and ounces here because I am not being
real precise.) Once I lowered the leading edge I could move the center of
gravity back nearly an inch. The glides lengthened and there was much less a
tendency for the plane to pitch up on a fast launch.

1mm depron - I'd be afraid to touch it.

Originally Posted by Whiskers

Interesting plane. Faster than a Hurricane, slower than a Spitfire and longer range and more ammo than either.
I'll be watching with interest. Good luck with it all.

Hey Whiskers, you're spot on. It could carry more ammo and fuel because the airframe was very light as it was built out of wood. The M20 was going to be a fast build emergency fighter to prevent the RAF running out of fighters early in the war. It's a shame it never got to production as I think it looks great.
Andy

Yes Andy, it is a nice looker.
I think it was also the first fighter to have a bubble canopy.
It probably would have acquitted itself a well as did the Hurricane, which did pretty darn well all things considered.

There's an echo in here! in here here

The Miles company had alot of proto-types , I had a list somewhere, but the M20 was on my list of future efforts and you did a great job building one. I think it looks to cool in that yellow and camo scheme, great job!, any plans in the future?

Jack, the depron is closer to 2mm than 1mm. Yes it marks up easily, and I
will do a few things to stop tears, there will be some tape on the leading edge
of the wing to stop the tears that start near the wing roots and like wise some
tape inside the fuse running a bit before and after the wing saddle for the
same reason. But the adage applies - build to fly not to crash.

OF, I don't know much about producing plans. From the drawings I do make there
is always a lot of ad-hoc fudge and fiddle.

On that first one I chose to use green and gray on the top side, mostly because
I did not have any brown paint I liked at the time. Last time I was in
Micheal's I spotted some small bottles of green and brown craft paint that
should work well on this one.

Thats ok, my plans ,I use my trusty pencil, ruler, compass, assorted odd things and then a few plan B fixes in the moment of the builds. You know the satisfaction, when it flys and you built it with your own two hands and with minimal swearing. Did you just go from a 3-view or did you use the TLAR method?

I've been working from 3 view's. I have one that is mostly from the first
plane, and another that is based on the second. The first plane had thicker
landing gear spats and a less pointy spinner.

As you can see from this series of photos I am using a series of 3 cylindrical
pieces for the main part of the fuselage. I am not using formers on the
inside, I force the curves by rolling the part over the edge of my desk, and
then use a series of outside formers to help it hold shape while the glue is
drying. I also use the outside former to help trim the end of the tubes as
needed.

I have mounted the motor in the front section and then attached it. I attached
the front section with a bit of down because the three views look like that was
how they built in the down thrust in the real one.

I'll be opening up the wing saddle and using that hole to put the servos, radio
and battery box in. I am also forming the buck for the canopy, I'll vacuum
form it and the radiator housing. I don't know how I am going to form the
landing gear spats yet.

How is the plane coming along?