My daughter likes birds. We have a field guide "bird book" in our library and she's always looking at it. Recently she asked if we could build a bird to fly. This was great, I wanted to strike while the iron was hot. While we wanted to build the type she is interested in from scratch, we also wanted to get one flying right away to keep interest up and see if we could get some of the local birds to fly with us (I've had a RC bird before, it was a "real" bird magnet).

While we started on her "scratch build" bird, we also bought an "EPP Eagle" to get another bird in the air right away. Basically it's a light weight foamie kit made from 1/4" flat EPP sheet. And, it also has a more sophisticated, reflexed and shaped hollow wing structure using carbon fiber rods as spars. So it's very simple yet sophisticated at the same time. You can buy one pre-painted or go for the "bare" EPP foam and make a custom paint job. The bare version worked for us, much cheaper and a blank canvas for our project.

The kit built up in one evening. We used hot glue and CA with kicker. I've never used hot glue before, let alone on a model. I was seriously doubtful but I'm convinced now - it works great for EPP. The model was painted the next day over a few hours. The motor is a Grayson Hobbies 2212-13 (like a speed 400 outrunner, 1000kv), APC 7x5 e-prop, 3s 2200 pack, will run at about 100 watts max but mostly at partial throttle to no motor power. Two 9g servos for the "V-Tail" control. It weighs under 17 ounces without battery pack, and I have packs for flight that range from 5 to 7 ounces. So this thing is going to be a floater at under 24 ounces worst case scenario - it spans nearly 60 inches and it has a wide chord - tons of wing area.

We used three colors of "PlasticCoat" spray can paint (brown, orange and light gray) and made several masks we cut out of paper. We misted a base coat down and shaded the feathers in using the masks. Typical stuff, working from light to darker colors. We painted the forward part of the fuselage by hand and used the "eye" decals that came with the kit. We chose to model a Red Tail Hawk to join the local population which is pretty plentiful.

I'll add some flight pictures when it flies. My daughter is really looking forward to the "real" hawks that may come out to join us. Several years back, I made a scratch built Red Tail Hawk and was able to attract many Hawks. There is a good population in the area so I'm sure we'll see some action with this one.

Here is a video of the place we normally fly the EPP Eagle "Red Tail Hawk" at. The fields and streams/dry creeks are home to a lot of critters where Hawks, Buzzards, Harriers and Falcons among other birds of prey feed and live.

For FLIGHT REPORTS see comments link to get into the extra posts located below the bird pictures at the bottom of this post.

A Stroll Through the Morning Air (3 min 21 sec)

Update: Wattmeter tests show the APC Slowfly 9x6 is way too much prop. I tested 20 amps and 220 watts. Since the ESC is a 20 amp ESC and the motor is really just a 170 watt motor, this is not going to work. So chalk one saved ESC and motor up to the wattmeter. I'll use a 8X4 possibly, but I have a 7X5 on hand and the maiden will probably be flown on that prop. This is not a "performance" model, so a slight "under prop" condition will be fine for the fist few flights.

Edit again:

The APC 7x5 prop flies the model great at a scant 100 watts on a 3s 1800 or 2200 30c pack at my 5000 foot altitude - at sea level I'm sure it would be appx. 150 watts). Totally over done on flight pack, but that's all I have.

The GWS 9x5 prop is more powerful at 160 watts. (sea level estimate at around 200 watts) This bird does not need 160 watts, in fact the 100 watts flew it great but I wanted a little extra in case I needed to escape from a Harrier attack. There are a few Harriers that live near by that have proven to be the only hostile birds but in any event, good to have the extra performance to escape if needed

Edit: Escape made with extra power!

The only time I fly the Bird with all the power she has, is when the Harriers come out to "play". Yesterday morning while flying from my front yard at about 300 feet, I apparently attracted the local Harrier team. The one that came to intercept me got to it's usual bullying with head on attacks. I decided to use the throttle and control throws to get out of range of that Harrier.

Interestingly enough I didn't realize a second Harrier was above me, until he / she broke off an attack from above just before contact - this was while I was engaged and fleeing from the other bird, who was at my altitude. They were using an interesting technique, obviously pioneered by birds and used for thousands of years or more... However, a derivation of this technique is a tried and proven aerial combat system used by humans. It was obviously "borrowed" from the birds by humans, now that I've seen it myself from birds.

Anyhow, us humans would call this "tag team" approach of aerial combat a "Thatch-Weave" tactic. A farm boy must have recalled seeing birds use this and he invented the name while flying F-6F Hellcats in WWII Pacific theaters - and soon enough the US Navy was pulling down Zeros like they were fish in a barrel using the technique during air combat in the Pacific. The Thatch Weave is a defensive maneuver designed to bring the hunter into a defensive position and in the cross hairs of the wingman of the hunted. In my case I was seeing something slightly different but close enough where a single aggressor engages the enemy close in while a second aggressor comes in from above, undetected, for the fatal strike. Pretty neat - glad I got away though.

Back to the bird mechanics: Just 70 percent of the listed "instructions" max throws is plenty for reasonable controlability. With 120 watts and full throws those Harriers were "out of there" in about 15 seconds. The two attempts to bully were done with gusto but ineffective enough to bore them into moving on to an easier target. See ya Harriers! Go back to scouting for food and I'll try to stay out of your way

Flight Report:
First flights went great! Even with the small prop and only 96 watts at full power, this EPP Red Tail Hawk flies beautifully. Floats great! Caught multiple thermals at only 945 in the morning. The only wild life we were able to get up and take notice were a few unidentified black birds and sparrows that did not appreciate the proximity to their nests. We had a few "pair" of birds on two separate occasions, come up and intercept us. Not wanting to overstay our welcome or harass the locals we moved on and gave them some good feedback that defending their nests results in the "boogeyman" moving along to easier targets. It was pretty cool to observe them escort us out of the area (one behind us and one above and to the right - we assume the nest was to our right and behind us...) They bugged out quickly once we were not a threat. Next up, we'll fly by our house where a lot more Hawks live as well as Prairie Dogs. The Prairie Dogs hated - and I mean hated - my last Red Tail Hawk I scratch built years ago. They would chirp up a storm like an air raid alert. Soon there were prairie dogs at attention in all quadrants chirping away in alarm mode.

There were a few joggers and walkers that were really interested in the flying Raptor - But I'm sure a lot more "little" eyes in the grass and trees were watching too but we didn't see "them".

Later Flight Reports:

Mid June-
So far I have not lured any "big hawks" to come out and fly with us. I probably came on too strong with one of the locals, she was sitting in a tree and after I circled over her a few times she was spooked and flew off.

We have about 15 flights on her in the first two days (if you include three 8 minute flights in one pack with thermals in between three landings to facilitate show and tell and "neck rest" - as being three separate flights). I think on most summer days this EPP Eagle could be flown for an hour (or more) on a single 2200 pack with good thermal hunting skills. Though the 1800 pack allows very low sink rates in still air, the 2200 gives the bird more penetration on light wind days and the ability to get around the field and swap thermals without as much power assist (the better penetration of the slightly higher wing loading is just noticeable).

Today was an OK lift day, we caught several thermals and averaged one minute of motor run time for every four minutes or more of thermal time. On at least three thermals today I intentionally exited the thermal as I was getting too high and my daughter was getting bored of the whole "high up and long flight" thing. Fair enough for a 7 year old. More low and slow loiter time and ground hog searching is actually more fun and keeps the kids interested. Time to get the buddy chord set-up, I think we have a willing new pilot now.

I have two timers set on the transmitter. One is a continuous timer for flight time. The second is a motor run timer. I have my alarm set on the motor run timer for 15 minutes. Continuous timer is set to alarm at 40 minutes to be conservative. One threat with a model like this is to run the battery completely down to nothing if you are using thermals to fly. Since it is only BEC, I'd hate to have a mostly drained motor battery and then catch a big thermal and 10 minutes later lose radio link due to a dead battery that would have cut off the motor (but we aren't running it in the thermal so we don't know) but is further drained to zero for the radio too.

Late June-
We've had many flights with Buzzards (flight of 6 including us in thermals), Harriers (two of them at once) and a few flirts with a Red tail Hawk family. The Harriers are the most aggressive, and don't like us being over their hunting grounds and will attack if they get a tactical advantage. The Red Tail Hawks are still a little shy but sho no signs of aggression. The Buzzards on the other hand almost seek us out and like the company! Maybe they think we will invite them to the feed party if we catch something. Small black birds, sparrows, mountain King Fishers, etc typically fly for cover unless we get too close to nests where they'll come up to escort us out of the area.

I thought I'd post a fascinating video about Bob Hoey's bird models here - some of the testing and data he collected is above the norm in model aviation. Bob has created a legacy for model aviation in terms of research in bird flight and model airplanes.

Bob Hoey's R/C Bird Models - A Short Summary (10 min 42 sec)

Another modeler's video of Bob's Turkey Vulture build:

Bob Hoey's Turkey Vulture (2 min 18 sec)

We are in the process of increasing our local robot "bird count" here in Reno to include some of Bob Hoey's designs. The EPP Red Tail Hawk is still going strong, but another couple birds would be interesting to see how the local bird population reacts to the new comers compared to our current Hawk. We were thinking about making a Turkey Vulture, or possibly a Pelican or a Seagull. More on that later.

Another interesting link to some bird designs:
http://www.twitt.org/subindex.htm#projects
http://www.twitt.org/1partdrib.html

And a few good threads here on RCG:
https://www.rcgroups.com/forums/show....php?t=1484283
https://www.rcgroups.com/forums/showthread.php?t=725527
https://www.rcgroups.com/forums/showthread.php?t=950519

Bob Hoey's Turkey Vulture plans can be purchased here (link below). The plans call for traditional balsa and plastic covering. EPP foam could be substituted with some re working of the plans, used for reference for those looking to save time. Though, the balsa design is a work of art and needs to be considered.
http://www.airagestore.com/plans/rc-...y-vulture.html

Very good PDF article about the Bob Hoey Turkey Vulture from another modeler:
http://www.rcsoaring.com/rcsd/RCSD-2006-05.pdf

For those still interested in RC birds after all this, here is a perspective not often seen. Riding on the back of a LIVE eagle is a camera that you get to look through.

Flying eagle point of view (1 min 26 sec)

I've bought a Dreamflight Alua - another bird like plank slope platform. I'll be painting her up in what I believe will be an American Kestrel scheme (blue, white, orange) and she'll be a slope glider to fly here on the beach bluffs.

Here is a cool video of an Australian Alula pilot mixing it up with some Magpies while trying to elude their attacks!

Magpie Glider - Slope Soaring Alula Attack (4 min 14 sec)

The other still photos are of my favorite local slope site, about 10 minutes from home. Much bigger air mountain slopes are within 45 minute to 1 hour drives. But the beach bluffs are quite family friendly and I can ride my bike to them with an RC backpack.

Another video with a Dreamflight Weasel. I love these bird interaction videos. My EPP Eagle (thread starting subject) has also logged countless escapes from Red Tailed Hawks, Harriers, etc.. as well as hours soaring with Buzzards, all too happy to share the skies.

Dream Flight Weasel Trek Slope Soaring and Peregrine Falcon Slope Combat (3 min 45 sec)

This video shows how birds of prey will often carry out a sneak attack from above. In soaring my EPP Eagle there were a number of attacks like this, from various birds of prey I was able to thwart. This is because from my perspective I could see the climb, overhead stalk and strike dive well ahead of time. The technique was to wait until a second before the bird was to strike and then initiate an aggressive, rapid pull up directly toward the aggressor - where they would overshoot the target bird and fly past and below. I'd then rapidly change direction. Thus, a follow-on turning and maneuvering pursuit was often too demanding for the aggressor to carry out, since it was well below and beyond the target now. This was similar to how jet fighters tactically avoided SAM missiles that had been tracking them and were destined to take them out in Vietnam. A last ditch effort to avoid being taken out.

How the Fastest Animal on Earth Attacks Its Prey (3 min 44 sec)

Dream flight Alula completed in April.

I chose to use a Falcon scheme. The Peregrine Falcon is a similar size to this model. She looks great on the slope - and weights only 6.5 ounces!

My other slope flyer is a Ryan F-8-F Bearcat, converted from speed 400 hand launch ops to slope ops. I’m really not sure how she will do but, to balance her out with no motor, she still needed a fair bit of ballast and weights 15 ounces all up. That a only a 2 ounce savings without motor and pack. She’s glass over balsa. I am probably dooming her By turning her into a slope flyer.... but it seems right. The spinner is “A La” Reno Racer “Rare Bear” style and also a way to reduce drag and a place to
keep weight to balance her out. She’s got a 31” span.

What Chickens dream,....

Graupner Funky Chicken RC Glider (2 min 14 sec)

Mr. Woodfield is from the UK, and has posted many videos of his unique gliders on youtube. Some are the most beautiful old-school balsa/monokote masterpieces ever. He also has a HUGE quiver of gliders that would make any R/C pilot drop their jaws.

Enjoy

Red Tail Hawk (Radio Control Model) (3 min 6 sec)