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Posted by kevinrc | Aug 28, 2015 @ 02:55 PM | 1,625 Views

Posted by kevinrc | Aug 27, 2015 @ 07:12 PM | 1,739 Views
There has been some question whether the stock UBEC in the Freewing T-45 is adequate.

My friend and I decided to find out. We restrained his airplane and first he then I ran the throttle to 100%, then cycled the landing gear, flaps and slats, and airbrakes, while moving the flight controls.

From 6 to 38 secs. was my friend, between 39 and 51secs we passed the radio, and between 52 and 77 secs. was me.

I believe this was a fair stress test even without any air loads on the flight controls, as I can't imagine cycling all those components at the same time while simultaneously moving the ailerons, elevator and rudder. Notice that the voltage remained at least 4.97V even at its lowest spike; neither I nor my friend saw any indications of brownout.

I see no reason to suspect the UBEC is not up to its task.

Posted by kevinrc | Aug 25, 2015 @ 12:04 PM | 1,990 Views
Earlier I related that one of Big Beautiful Doll II's flap servos was defective from the factory, and MotionRC sent me a replacement.

Only after I installed the replacement and was connecting the flap pushrod did I notice the left and right flap servo horns were different. "No problem", I thought. "I'll just use the horn from the original servo."

Not! The new servo's output shaft pinion is different from the old one:

The new flap servo is on left; the original servo is on the right. Although the servos have the same FMS part number they are obviously not interchangeable.

MotionRC is sending me another new servo to match the first one.

FMS promotional material leads one to believe that one of the improvements for v8 was metal-geared servos. The exact wording is "New 17g hybrid metal gear servos". MotionRC researched this claim and reported that only the 17g servos were upgraded to metal-geared.

While I continue to be impressed with MotionRC's customer service, BBD II will be my second and last FMS airplane. Deceptive advertising and undocumented changes to planes and spare parts appear to be FMS practices, and I won't support them anymore.

I now advise people looking for a P-51 in this size range to try the Freewing model.
Posted by kevinrc | Aug 23, 2015 @ 12:51 PM | 1,467 Views
I fly from a grass field, and unless the grass is freshly-cut I may sometimes nose a plane over. This has resulted in broken vertical stabilizers and interruptions in flying.

To prevent this, I epoxied a 1/8" carbon fiber tube into the vertical stabilizer of each plane.

I don't remember where I bought my long 1/8" drill bit (perhaps Home Depot). I positioned it on the vertical stabilizer and marked it for depth with a piece of tape:

With the plane assembled and upright, I stood behind it and aimed the drill at a point along the centerline of the stabilizer and even with the elevator's plastic joiner.

With the hole drilled I removed the stabilizer and mixed a batch of Finish Cure epoxy, applied a small amount to the end of the carbon fiber tube, and inserted the end. Then I worked the tube in a little bit at a time, adding epoxy along the next inch and working the tube in until its top was just below the surface of the stabilizer's top edge. A little epoxy smeared along the top edge of the stabilizer and rudder adds a bit of scuff resistance.
Posted by kevinrc | Aug 23, 2015 @ 11:36 AM | 1,447 Views
We owners and pilots of FMS models are well aware how soft and easy to damage is this foam. I had (and may again) considered fiberglas-ing the entire model to make it more damage-resistant. Well, maybe just the wing and tail leading edges.

OK, maybe not fiberglas but plastic laminate sheet. RCGroups member Jacksmobile sells plastic laminate, and I ordered some 30-mil sheet from him to do wingtips and leading edges.

It's applied using a monokote sealing iron. I set mine too high in the beginning, and some of the foam alligator-skinned. I'm setting the iron at ~1.5 now.

Covering the wingtips is not fun, as their top surfaces are compound curves. I used separate pieces for the top and bottom, inward to and including the red stripe. I cut around the navigation light lenses and trimmed to exclude the aileron.

I covered the wing leading edges to the first panel line.

Paper templates were cut, fit multiple times and trimmed precisely before I transferred their outlines to the laminating film. I had the best results laying the film shiny-side-up, and using a Sharpie to mark corners. I then laid a metal ruler between the corners for the cuts. Isopropyl or denatured alcohol takes the Sharpie marks off before using the sealing iron.

This view of the wing shows the templates I used laid out in their approximate relationships to the wing; the "top" of each template lays along the first top panel line and the "bottom" lays along the first underside panel line. (I skipped the panel with the machine guns.)

Posted by kevinrc | Aug 18, 2015 @ 07:37 AM | 1,314 Views
I recently destroyed my two-year-old Big Beautiful Doll v7, and bought a Big Beautiful Doll v8 to replace it.

Although new-production v8 P-51s come with an FMS New Multi-Port Connector, mine came with the older Main Wing Multi-Connector Part 2.

MotionRC stepped right up and sent me the new multi-port connector board; when it arrived I and two friends stood around the model trying to figure out where to put it. The only place large enough was just forward of the hole in the fuselage where the wing connectors come through, and the receiver leads were too short to reach the place I wanted to put the receiver. If I cut some foam and put the board where I wanted to put the receiver, the part 1 wing connectors wouldn't reach it.

In addition, the board has plugs for the rudder and elevator servos, but I couldn't see plugging them into the board and plugging the board into the receiver, when I could just plug the rudder and elevator directly into the receiver.

In the end I decided to use the supplied parts and count my blessings. (I'll send the unused new multi-port board back to MotionRC.)

Below is the overview of my fuselage interior arrangement. The receiver satellite is out of view on the left side of the photo, as far back as I could reach on the left sidewall. I plugged a Y-harness into the receiver Bind/Data port, with one leg going to the TM1000 telemetry module. The other leg, shown hanging over the side, is a bind extension.

Inspired by Sandancer's Big Beautiful...Continue Reading