Pitts style biplane scratch build

I really like the styling of the Pitts biplane, so I thought I'd try to make something similar. I also like the 750mm wingspan size which is right around 30". It makes for a nice size to transport but still gives a decent scale to keep orientation in the air.

I posted this a while back in the forums but thought I'd add it to the articles now that I've proven it can fly.

     This is the link to the foum thread:
     http://forum.flitetest.com/showthread.php?16115-Pitts-style-biplane-scratch-build

(plans are linked to in the forum thread on the first post)

(link to maiden flight video is at the bottom of this article)

The name:

I named this plane 750 - Fitts. I'm hoping it doesn't give me fits when flying. (think happy thoughts)

Design choices I'm not so sure about:

One thing I'm not sure about is that I only put the ailerons on the lower wing. I didn't do corresponding ailerons on the upper. I did make the ailerons oversize to hopefully gain some authority. If it doesn't fly well, I could always cut in upper ailerons and link them together.

One other change, to the original scale design, is a larger rudder. I also made two changes (one was a mistake) during the build process. First, I mounted the landing gear farther back than the scale location. It seemed like a good idea to have it mounted right at the front of the lower wing for good support. The landing gear location might make it tend to nose-over during landings. The bigger mistake was when I mounted the upper wing. I centered it on the upright struts which shifts it more forward than an actual Pitts. Will the accentuated "stagger" make it fly worse? It seems to fly pretty well but I need to fly it more to really learn it's characteristics.

I don't try to build as "swappable." I've decided that for my purposes, I would rather dedicate the electronics to each plane I build. That and it makes it a tiny bit lighter because I don't have the extra foam board for the power pod.

I made this out of standard Dollar Tree foam board and wrap all of the parts with clear shipping tape for durability.  I also peel the paper off of the inside of the fuselage just to drop some weight.

Notes on the design:

- 3/16" wood dowels in the wings for spars
- barbecue skewers shoved through the foam board upright wing struts
- bottom of fuselage left open to reduce weight
- CG is a bit tricky and I'll have to see how it flies
- had to mount the battery right behind the firewall to get where I think CG should be
- I didn't separate the aileron servos for flaperons (might do that later)
- I laminated a second layer of foam board on each wing to create a KF airfoil
- the fuselage is a bit wider than scale - I wanted it to be pudgy, go figure
- I may put a smaller prop on it, once I maiden it, just to get longer flight time
- no plan for a canopy - easy access to everything
- I used fishing line for the wire reinforcing between the wings
- firewall is a plastic tray from a 2.5" SSD - I get a lot of those from work
- the wire landing gear are for an Art Tech plane that I soldered some reinforcing wires onto 

Here's the specs:

- 30" wingspan (approximately)
- 671 grams flying weight with revised landing gear (measured)
- EMax CF2215 1200kv brushless
- HobbyWing 30A ESC
- 1300mah 3s LiPo
- LemonRX DSMX receiver with stabilizer
- 10x4.5 GWS style slow fly prop
- EMax 9g analog servos
- 21.2A draw at WOT (measured)
- 823 grams thrust (measured)

Here's the CAD view of the profile and the Pitts photo that I used to trace the basic shape.

Friendly advice:

I had a suggestion from one of the forum members:

Orginally Posted by jamboree1

Build photos:

And here's the maiden video: