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herk1's blog
Posted by herk1 | Apr 13, 2015 @ 03:11 PM | 1,661 Views
I got a Bix3 for FPV, and especially wanted to do takeoffs and landings in FPV. But the ground-handling with the stock tail-dragger Bix3 landing gear was atrocious. The plane would jerk 90 degrees to one side as soon as the tail gear lifted off the ground on takeoff roll. I finally fixed that by bending the main gear wire (which appeared straight to begin with, but whatever works...). That fixed takeoffs, but then landings were messed up -- the plane would ground-loop right after touchdown. The stock tailwheel mount is really a loose, rickety affair, and the long pushrod which splits into two rods (for the rudder and the tailwheel) is flimsy and a pain to deal with.

So I modified my Bix3 to give it tricycle landing gear. Now the ground handling manners are solid and smooth for taxi, takeoff and landing. I used this trike-gear set:

The main gear is mounted onto a piece of lite ply of similar dimensions as a paint stirring-stick, which I threaded through the fuse foam at an appropriate distance aft of CG.

The nosewheel part fit like a glove onto the Bix3's nose, with very little trimming -- all I did was expand the cooling inlet forward to the edge, then slide the nose-gear servo shroud into the slot (secured with hot glue). Photo attached (I temporarily removed all my FPV gear to test the gear mod). I haven't decided if I'll put the nose cone back on or just leave it open for cooling.
Posted by herk1 | Feb 06, 2014 @ 02:53 PM | 3,089 Views
There are lots of mini-warbirds available these days...but unfortunately they either come with fixed landing gear, or no landing gear at all. So I modded my FMS 800mm mini Bf-109 with the smallest set of electric retracts that I could find. The retracts I used are these:

They do not come with struts. They fit a 3mm strut wire -- which is fatter than really needed for this small of a plane. And unfortunately, they do not come with securing screws to hold the strut you need to improvise something for that. My improvisation was to file a small notch into the strut, then secure it with a #2 by 3/8" screw that I had in my supply from a previous RTLFasteners order. You have to be careful not to tighten the screw too much, or it will strip/ream the plastic.

The stock landing-gear mounts are held on with a rubbery contact cement, so they pulled off with a steady pressure without tearing any foam. I covered up the remaining evidence of the original gear-mount depressions with some 3mm Depron (photo).

I mounted the retracts in a thick part of the wing (where the original gear mount was located), then bent the struts forward so as to site the wheel-wells more forward, to minimize nose-overs/tipping. (Yes, I know that the retracts on the real Bf-109 swing the other way.)

The attached photos pretty much tell the rest of the story.
Posted by herk1 | Aug 13, 2013 @ 06:08 PM | 5,031 Views
This plane is a new model in the "funfighter" series of little (around 24" wingspan) EPO warbirds. I bought the ARF/airframe kit, which is all that I have seen available so far. Unlike some of the other Skyangel airframe kits I have bought previously, this one did not come with the motor.

The plane arrived with the two other Skyangel planes that I ordered at the same time, in a big, beat-up looking package. Turns out, two of the Skyangel boxes inside were nearly flattened. The P-39 damage was a bent and cracked fuse as well as a bent wing (polyhedral added as a bonus, I guess you could say). After some work with a hairdryer, the shape is restored, with only appearance-damage (wrinkles) remaining. These aren't the first Skyangel planes I have received in flattened boxes. They really should rethink their packaging.

This kit actually came with two sets of prop/spinner parts -- two-blade and three-blade. On the package with the 3-blade parts, it says: "If use 3-blades propellers we suggested data as below: ESC:30A-40A, Motor kv: 1500-1700, Battery: 1000-1500mah 3S 30c." Both versions have some nice yellow accent paint added, as per the full-scale scheme that is modeled (see link below).

The interior elevator control rod routing, and the nice long equipment hatch along the top follow suit with other funfighters. How much room is inside the P-39 for bigger batteries and equipment placement? See photo for a comparison with the Corsair and...Continue Reading
Posted by herk1 | Jan 05, 2012 @ 06:39 PM | 4,353 Views
This tiny 12-inch-long foam chuck glider (link) seemed perfect for conversion to RC using micro components.

My first idea was to use the "brick" ESC/RX/servo unit from one of the Horizon micro planes. So I cut off the top from the Shuttle with a hot-wire, dug out some room, then transfered the "brick" and motor/gearbox from a Hobbyzone Champ to the Shuttle...adding Depron elevons onto the rear of the shuttle for control (see first photo below). Unfortunately, when I test-flew this configuration, the Shuttle could only manage a controlled descending glide to the ground. Apparently the Shuttle needs more speed to fly than the rather low-pitch-speed power setup of the Champ provides.

But I'm not one to give up after a single try. For my second try, I ordered one of those tiny new micro-size Spektrum-compatible receivers from HobbyKing (it weighs only 2-grams), and some tiny 1.7-gram servos to go with it. Then I stripped another micro plane in my hangar of it's high-RPM 5-gram brushless outrunner motor and 7-amp ESC. For a battery, I chose the smallest 2S LiPo that I have -- a 200 mAh one.

This new configuration surprised me with the dramatic difference in flight properties. Now the Shuttle climbs strongly at full power (almost too strongly in seems as though a thrust angle adjustment may be in order). The Shuttle even cruises along happily at only half power. The only real problem on the remaiden was the touchy roll rate, because I still had on the big "paddles" for elevons that I had sized for the slower original configuration, and excessive throws to boot.
Posted by herk1 | Oct 27, 2009 @ 05:28 PM | 6,139 Views
A popular kit, but it's an old design originally intended for brushed power. Put a couple of brushless motors in it and it needs some strengthening modifications.

I started with the slope glider kit, which comes with no fans. For power, I'm using two GWS "green" brushless inrunners, and two brushless ESCs (Thunderbird 18). I had to buy the GWS shrouds that have a receptacle for 20mm inrunner motors, and the GWS 55mm rotors with D-cut. I already had the D-cut hubs for 2mm motor shafts from my GWS F-15 kit (the same hubs go with the 55mm and 64mm fans). For a battery, I'm using a single 3S LiPo of about 2200 size. When I was finished building, I was happy to find that the plane balanced with no added balance weight, with the battery located exactly where I wanted it: under the aft part of the canopy, just behind the nosewheel wire. Final AUW after painting is 26.6 ounces.

Here are the modifications that I made to the kit:

1. Made large topside battery hatch, and plugged up the stock battery hole on the fuse underside with a scrap foam piece. To create the hatch, I cut the fuse along the panel lines around the canopy, then dremeled out the insides of the fuse down to the floor to make room for a 3S 2200 LiPo. To hold the top hatch on, I installed two popsicle-stick retaining tabs on the front of it, and two rare-earth magnets in back. I also installed a lite-ply floor for the battery, with velcro on the floor to prevent sliding, and two velcro...Continue Reading
Posted by herk1 | Feb 02, 2009 @ 03:46 PM | 7,876 Views
I like pusher-propjet models. This will be my fourth. The GWS J-10 is big, sleek-looking, and has canards that actually function -- instead of just being a glued-on/fixed decoration (like so many models of planes with canards). How cool is that?! And it has a stick mount option for pusher-prop power. So it was just a matter of time till I got around to building one.

Here's my setup:

GWS J-10 NPS kit (white/unpainted)
Scorpion 2215-1860 motor (outrunner, 1860 Kv)
APC 7x5 Sport prop
Pentium 40 ESC
Epyaya LiPo battery, 3S/2200 mAh
GWS and Hitec servos
Spektrum AR6000 receiver

The motor is one I've been anxious to try out. It's one of two Scorpion motors that is specifically suited to pusher-propjets. See this announcement.

I'm also trying out a Pentium ESC from Don's that has a built-in switching BEC, instead of my usual Thunderbird ESC with Dimension Engineering BEC. It's more simple (less wiring rat's-nest, less soldering), and cheaper. Hope it does the job as well.

I'm getting close to finishing the build. I'll post more photos when I get a chance. For now, here's a photo of the kit and some of the components.

[edit: more photos and maiden report added, in "Comments"]