Todd Ferrante's Big Red Aerial Photography Plane

by Todd Ferrante  <back to homepage>
last edited 12/13/2006

Background: My previous aerial photography planes have been canard planes.  Canards have two pluses for AP: 1) They tend to be pushers, so the prop is not in the field of view of a forward looking camera. You want the camera to be forward looking to minimize motion blur. 2) The CG of a canard plane is back near the leading edge of the main wing. This normally means that the camera is pretty well protected in a nose-in crash.

There is one big minus. A canard plane needs to be landed with a bit of speed to prevent nose-ins. For stability, in a conventional plane the main wing stalls before the tail. This ensures that the nose drops, airspeed goes up, lift returns and recovery occurs. In a canard plane, the canard stalls before the main wing for the same reason. In a conventional plane, with the main wing in stall, you still maintain pitch control with the elevator in the tail. In a canard plane, if the canard stalls, you loose pitch control.

When flying AP missions, your landing sites are usually not optimal. There usually isn't room for long takeoffs and landings. For this reason, and also to protect the camera, you want to land as slowly as possible. In the canard planes I built, I would end up stalling the canard when slowing to land. If this happened a couple feet from the ground, there was usually no problem. But, I had enough nose-ins from head height to make me want to either redesign the canard, or to switch to a more conventional layout.

Design goals:
I've decided that my next AP plane will be a conventional winged, twin boomed pusher. The pusher gets the prop behind the camera, and the long nose provides a measure of protection for the camera.  There has been much talk on RC Groups about how GWS Slow Stick wings are great for slow speed, heavy payload planes.  They are also quite inexpensive.  I decided to use two slow stick wings as a basis for my new AP plane.  I stuck with my tried and true technique of using carbon fiber arrow shafts for the main structural components.

Big Red, mark 1 (11/5/06):
I had purchased two replacement Slow Stick wing/tail sets back in the spring.  These were a great deal at $10 per set.  They pretty much sat around as I was busy with other projects for most of the summer.  I finally got a free weekend with nothing else happening, so I sat down and banged out this plane in one weekend.  On Saturday I built the wing.  On Sunday I completed the plane and got in a test flight right at sunset.

The wing spar is two carbon fiber arrow shafts spliced tip to tip.  These arrow shafts have internal threads at the front for attaching arrowheads.  I connected them using a short piece of threaded rod of the appropriate size.  The central section of the wing is a single Slow Stick wing with the dihedral removed and the tips cut off.  I spliced the two halves using strips of thin Depron hot glued to the interior and crossed strips of fiberglass tape on the outside.  The carbon spar runs along the top surface of the wing in the center section.  The outer sections of the wing have dihedral such that the spar starts at the top of the wing and ends at the bottom of the wing.  I cut some foam ribs to secure the spar in the wing tip sections and to support the lower skin.

Picture moved to plane details page.  12/31/06
Interior of wing before bottom skin was added.

Before adding the bottom skin I cut ailerons in the wing tip section, following the original lines on the Slow Stick wing.  I suspected these would not be large enough, so when I skinned the bottom, I left room to increase their length.  After installing aileron servos, I skinned the bottom of the wing with .10" thick depron.  This construction was done with hot glue and fiberglass tape.  The final wingspan is 81 inches.

Picture moved to plane details page.  12/31/06
Tail detail.

I used the parts from the two Slow Stick tails to make a new tail with a larger elevator, and twin rudders.  The rudder and elevator servos are mounted on the tail, so the entire tail can be removed for transport.  The nose was done quickly to enable a test flight before dark, and was changed later, so I won't show the details.

Big Red, mark 1.

Test flights at the Yorktown battlefield showed that there was plenty of motor thrust to fly the plane.  There was an abundance of pitch control, even after the tips of the elevator broke off when landing.  As I had suspected, the ailerons were undersized, and there was almost no roll control.  I was able to use the rudder to make a single circle, but keeping the wings level was nearly impossible.  The flights were pretty ugly and showed I needed to enlarge the ailerons and come up with a better fuselage attachment scheme.

Big Red, mark 2 (11/12/06):
I let the plane sit for a week and then did repairs and modifications the next weekend.  Crashes on the test flights had caused some delamination of the lower skin where the hot glue had cooled too much at the original skinning.  I fixed the delamination with foam safe CA.  I extended to ailerons to the inner and outer wing joint, more than doubling their length.  Since there was plenty of pitch control on the first test flights, I trimmed the easily breakable ends of the elevator away.  I also added a nose attachment method using two more arrow shafts attached to the wing with rubber bands, like the tail. Unfortunately, it rained all weekend and test flights were impossible. 


Big Red, mark 2.

I never made it home from work before dark that entire week, so could not do more test flying until the following Saturday.  Janelle agreed to come with me and take pictures, so she got to witness the thrill of a completely successful test flying session.
After first successful test flight.

From the first toss, the plane behaved wonderfully.  The lengthened ailerons gave plenty of roll authority for well controlled flight.  I'm not going to be rolling this plane, but that was never the intent.  Even with the reduced elevator area, there is tons of pitch authority.  The plane will do incredibly tight loops.  Turns tend to be made with a combination of ailerons and rudder.  I'm glad that flying my 3D foamy has given me the feel for rudder turns.  Coordinated turns are a must with this plane.  The balance of the plane doesn't seem to be a problem at all.  I changed battery packs, and added a video camera, and as long as the CG is about 1/4 to 1/3 chord, trimming for level flight is easy.

The long wingspan of the plane makes it very stable in roll, even docile.  I glides very nicely, and can go quite a ways a couple feet from the ground, coasting along in ground effect.  Of all the planes I've built, this one lands the nicest.  Next step is to modify the nose for the digital camera...
Mark 2 in flight.

Big Red, mark 3 (12/10/06):
Well, the Big Red AP plane is officially a success.  Despite a few mishaps, I find this plane to be a most excellent platform for aerial photography. 

The first mishap occurred on the weekend before Thanksgiving.  I was up at the Yorktown battlefield experimenting with different camera and battery placements.  Both the camera and battery were held on by rubber bands.  Though I wasn't flying at all aggressively, somehow the camera slipped the rubber bands that held it to the plane. It fell about 50 feet or so onto grass, and I was surprised it still worked. Unfortunately, it only worked for the rest of that day. When I tried to take some more pics with it a week later, I found that it was acting erratically, and it finally quit. But, if your camera is going to give up the ghost, what better day than Black Friday?  This camera was a Kodak Easy Share C315 (5.0 MP) that I picked up last year on Black Friday for $99 with the expressed intent that I could beat it around doing AP and not be upset if it got trashed.  I scanned through the adds and did some shopping that afternoon and ended up with an HP Photosmart M627 (7.0 MP) for $125 from Office Depot. It has an optical zoom and a metal case so, unfortunately, it is heavier than the Kodak (7.8 oz vs 6.9 oz). On the other hand, it has the lovely feature of a burst mode, where it will continue taking pictures as long as the shutter button is held down. I'm thrilled! No more manipulating a switch on the transmitter to take pictures!  I made a new, more secure camera mount that has been working great ever since.

Picture moved to plane details page.  12/31/06
New camera mount.  Rubber bands go around the "ears" and wrap around the nose.

The second mishap happened when I was flying at Denbigh High School, taking pictures.  It was pretty high up when the plane suddenly went into a dive.  I pulled back on the stick to bring the plane out of the dive, but nothing was happening.  I finally yanked back all the way and the plane slowly pulled out of the dive, barely clearing the tree tops.  I immediately landed and found that the right vertical rudder had snapped off at it's base.  The rudder was attached by it's tie rod, but was pressing down on the elevator, keeping it from pivoting upwards.  This was nearly disastrous, but easily repaired.
Nearly fatal dive at Denbigh H.S.  The first picture was taken at 3:59:12pm.  Then at :16, :18, :20, :24.  Better think fast!

Aside from these exciting moments, however, I've gotten in many more uneventful flights of successful picture taking.  On the weekdays I'm at work from dark to dark, so I'm trying to fly as much as possible on the weekends.  If I try I can get in three batteries in the morning and three in the afternoon.  At about 8-9 minutes per pack, that ends up being about 45 minutes to an hour in the air.  That gives me hundreds and hundreds of pictures to sort through while the batteries are recharging.  The burst mode is a wonderful thing.  I hope I never have to do AP again without it.  I get tons more pictures, and the pictures are of higher quality than with the previous camera on previous planes.  I'm making my way around this side of town, flying from any school with a baseball or football field.  I've got quite a collection of aerial photos of the Denbigh area of Newport News.  I'm enjoying the challenge of mentally picking a "target" and then working the breeze direction and lighting conditions in an attempt to get quality photos of my selected target.  It's a challenging and fun exercise, not unlike fishing, in a way.
Big Red, mark 3.

My most recent flights have been experimenting with the video mode of the digital camera to capture low altitude video.  I've also been playing with the "landing" switch on my transmitter.  This switch lowers both ailerons, as "flaperons", to slow the plane down and give more lift.  Simultaneously the elevator is raised, to counteract the nose down pitch than happens when the flaps go down.  I've tweaked the settings so I can cut the motor and flip the landing switch, and the plane will just float down to the ground nearly hands-off.

Update 12/31/06:
I've been flying this plane quite successfully for over a month now.  I've even gained enough confidence in it to hand launch it and land it in the street in front of my house.  Still scary, but doable if it's dead calm.  The design has stabilized enough that I've set up a second webpage showing some of the key construction details.  I've used the plane to take some really nice pictures, and have printed 8x10 glossy pics for my next door neighbor and for a restaurant we frequent regularly.  The flight from my street produced the best pictures of my house so far, one of which is below.  The shadows are a bit extreme because it was taken at  8:43am.  The light is much better at midday, but there is more car and people traffic on the street.  It may be less if I were to try it on a workday, but more people are around on weekends and holidays, when I've been able to fly.
Taken on the morning of 12/24/06.