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Old Dec 29, 2004, 01:38 AM
2 Mistakes Downwind
ToyBoy's Avatar
Portland, OR
Joined Nov 2004
414 Posts
Enough procrastinating...

I've been slacking off a bit. I still have a few more posts to do on this thread.

As I mentioned above, my first maiden attempt was aborted when my ESC failed. Fortunately, I had a spare ESC, a Jeti JES 110, which is rated to 11 amps continuous (the Pixie 20P that came with the Magpie is rated to 20 amps). I wasn't sure whether the lower power Jeti would be okay to use, so I asked around and was given the thumbs up over in the Parkflyers forum. My next opportunity to attempt a maiden was five days later Christmas Eve. I'll get to that soon.

In the mean time I decided to make some improvements: I hid some of the wiring inside the fuse, remounted the landing gear, and added a steerable tail wheel. I'll blather about these things a bit, but try to keep it short (I'm not good at that).

First I hooked up the Jeti and tested it. The downside of this ESC is that it's much larger than the Pixie. However, I know that the Maggie is capable of lifting plenty of weight, so I decided not to wait for my replacement Pixie and to just mount the Jeti permanently.

You can see the progression of the rewiring in the pictures below. First I decided to get rid of the bulky Deans Ultra connectors and solder the ESC output directly to the motor leads. Once I had decided where to mount the ESC, I cut grooves in the fuse for the wires to hide in.

You'll notice in the final pic that the foam is bare under the Jeti. This wasn't exactly intentional. I had cut some of the wing tape off when I removed the landing gear, and I didn't want to apply new tape until I had finished the rewiring and the new gear. So I went ahead and without really thinking, glued the Jeti in place, making it impossible (well, difficult) to replace the tape under it. Never mind.

The third and fourth shots show how I routed the ESC's RX lead to the RX. I couldn't cut a groove from the switch location (oh yeah, by the way, the Jeti has a power switch, unlike the Pixie) to the RX because the strapping tape is in the way, so I bored under the tape and pushed the lead through the hole.

I dug a hole for the switch and glued it in place. The last shot shows the job finished and ready to be covered with wing tape. You can also see the notch I cut in the fuse for the landing gear.
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Old Dec 29, 2004, 01:52 AM
2 Mistakes Downwind
ToyBoy's Avatar
Portland, OR
Joined Nov 2004
414 Posts
Remounting the main landing gear

My first job of mounting the landing gear was pretty ugly, and it also made it very difficult to measure the CG because of the bulk protruding from the underside of the fuse at the exact point where I was trying to balance the plane. This alone was reason enough for me to re-do the job. The first time, I simply attached the gear with double-sided tape (the kind used for mounting hooks around the home and stuff like that), and then attempted to cover it all over with wing tape. It didn't look good. This time, I cut a notch out of the bottom of the fuse, cut the sides off the LG mount, and added balsa to the underside of the mount to hide the lumpy bits. The end result is that it is nicely flush with the fuse when mounted. This makes it easier for me to balance the plane when checking the CG, and also looks much better. See before-and-after pics below. Cutting the side pieces off the LG mount somewhat reduces it's structural strength, but it doesn't seem to be an issue. The double-sided tape I used (again) to stick the gear mount to the fuse is REALLY sticky.

The last shot shows how much better it looks with the newly mounted gear and the hidden wires.

One thing I haven't done yet is hidden the servo leads in the fuse -- they are just covered with wing tape. That's on the to-do list.
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Old Dec 29, 2004, 02:36 AM
2 Mistakes Downwind
ToyBoy's Avatar
Portland, OR
Joined Nov 2004
414 Posts
Adding a tailwheel

Before my first attempt to maiden the plane, I hurriedly improvised a tail skid, because I knew I would be doing ROG launches from and landings on a baseball diamond and I didn't want to damage the bottom of the tail. It was hurried because it was late the night before my scheduled maiden (which was to be first thing in the morning) and I wanted to get some sleep. I was pretty happy with my quick & dirty solution: I cut the top of the hook off a wire coat-hanger (the crappy kind from a drycleaner), and taped it to the side of the tail with Scotch Extreme and some other reinforced packaging tape. See pic below.

I never got to take off with this skid, but I did taxi around a parking lot with it. It was almost impossible to control the plane -- it always wanted to turn one way or the other. I guess the metal skid didn't provide much friction to prevent lateral movement, especially on asphalt. Plus it wasn't centered on the fuse. I think it would have worked okay on dirt or grass.

However, since I had five more days until my second maiden attempt, I decided to replace my coat-hanger skid with a real tailwheel. When I went shopping for the gear, I found a nice looking steerable wheel bracket that uses the rudder for control, and although I knew it would be heavy, I coudn't resist it.

The second shot shows the gear I bought. The tailwheel bracket in the middle was a fixed bracket which I bought as an alternative if I decided not to use the steerable. It would be considerably lighter and would surely do the job perfectly, but I decided to go for the gimmick of the steerable anyway.

Wheel: Sullivan 1" tailwheel, solid rubber wheel/aluminum hub
Bracket: Sullivan steering/castoring tailwheel bracket for 2 to 6 lbs
Alternative fixed bracket: Du-Bro tailwheel bracket for .40 size planes

This is definitely not a weight-conscious tailwheel solution.

To mount the bracket to the tail, I glued a piece of 1/32" plywood (with the blind nuts placed in the holes first), and added tape on the ends for extra strength. I think I should have used a thicker piece of wood, but I think this will be okay. The important thing, because it is 3-ply, was to cut the piece with the grain direction running fore-aft, so that two of the three plies were providing strength along the bracket. (I hope that made sense). Before mounting the bracket I covered the wood with wing tape. I fixed the wheel in position on the axle by soldering washers to the axle on either side of it.
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Old Dec 29, 2004, 02:39 AM
2 Mistakes Downwind
ToyBoy's Avatar
Portland, OR
Joined Nov 2004
414 Posts
My better-half is telling me it's bedtime.
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Old Dec 29, 2004, 07:16 AM
Rat
Come get me if you can
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Rats nest Grafton ND
Joined Aug 2004
2,249 Posts
I have not received my battery pack and connectors from MM yet. Wish they would show up soon so I can go flying. How about it Doug, and did you get my other order?????
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Old Dec 29, 2004, 12:28 PM
Mountain Models Wannabe
CoClimber's Avatar
Ithaca, NY USA
Joined Mar 2001
4,371 Posts
Rat,

I'm pretty sure everything is shipped. Drop Karen an email if you want to check. They won't let me leave the R&D department to see what is going on in the rest of the company.

Doug
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Old Jan 02, 2005, 06:57 PM
Registered User
Newark Ohio
Joined Sep 2001
573 Posts
Cog

OK, so I get this COG right, it is 1/4 to 1/2 inches behond the back of the spar right? And the spar is the piece of plastic strapping that we glued on both sides of the wings.

Also, is this the COG for both wings, as I bought both wings. Thanks!!!!
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Old Jan 03, 2005, 12:03 AM
2 Mistakes Downwind
ToyBoy's Avatar
Portland, OR
Joined Nov 2004
414 Posts
Hivoltage,

I believe it is the correct CG for both wings, as the manual doesn't specify otherwise.

Thanks for reminding me that I need to get off my butt and finish this thread!
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Old Jan 03, 2005, 12:35 AM
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Gardena, California, United States
Joined Feb 2004
736 Posts
I check both wings by placing my fingers right behind to strapping tape on both wings, and have had no problem with it there. Good luck.
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Old Jan 03, 2005, 03:36 PM
2 Mistakes Downwind
ToyBoy's Avatar
Portland, OR
Joined Nov 2004
414 Posts
The Maiden (finally!)

Christmas Eve was the day I finally had the pleasure of seeing my work come to fruition. It was a sunny morning with calm winds of less than 5mph. With two 7-cell 900mAh NiMh packs, I went to the huge (40 acre) athletic park where I've enjoyed learning to fly over the past couple of months. I found a nicely hard-packed baseball diamond from which to take off.

I roughly followed the guidelines in the manual for setting up the throws for a gentle first flight. I set my rates to 50% for rudder and 60% for elevator. I also set up dual rates for 75% on both rudder and elevator to try some more responsive flying later. And to be even more cautious, I gave myself 50% exponential on rudder and 35% on elevator. Note that this was the first time I had ever used a computer radio, so I wasn't sure how my numbers would work out.

I had attempted to set the CG, as the manual indicates, about a quarter to half an inch behind the wing spar. Unfortunately my bird was quite tail-heavy (not surprising considering the tail gear), so I found it necesary to place some weight on the nose. It took 6 quarters (I didn't have any lead weights) to bring to CG forward enough. I also had a penny on one wingtip for lateral balance.

Flight one: she took off in about 20 feet. I gave her too much elevator (being used to the T-Hawk which needs full elevator to ROG), so she rocketed up pretty fast and then the nose dropped to a more sensible angle as I reduced elevator, and she climbed easily. However, I quickly noticed that the CG wasn't right. The bird was porpoising and I had trouble getting control of pitch. I brought her in for a CG adjustment. My first landing fell just short of the runway (the baseball diamond), but she stayed on her feet.

I put another 3 quarters on the nose. I was now sending $2.26 into the air along with my priceless new Maggie.

Second flight: perfect. No more porpoising. A little trimming and she flew gracefully and oh-so-easily. As advertised, the Magpie is slow and a pleasure to fly. After my T-Hawk, this was such a relaxing and enjoyable plane to fly. The T-Hawk isn't hard to fly, but the Magpie is much more docile with the throws as I had them set.

I had a very enjoyable 40 or so minutes of flying, including several ROGs and landings, and even I even tried a couple of touch-and-goes, my first ever! They were more bounce-and-goes really, but successful! I also did some loops, and even attempted a couple of barrel rolls, which were semi-successful, albeit with much loss of altitude (I have since done some much better ones using the higher throws I set on my dual rates).

I'm not happy about the extra wieght I had to add, and it will only get worse with the Kan650 batteries since they are considerably lighter than the 900's. So I will either remove the heavy tailwheel and replace it with a lighter one, move the battery forward a lot, or both. I suspect just swapping out the tailwheel won't be enough, so I think I'll have to move the battery forward. That's a bit of a bummer as I don't think I'll be able to hide the battery completely anymore, but I'd rather lighten the bird and have better performace and longer flights.

All in all, a successful maiden day. I didn't even come close to crashing. The Maggie was fun and relaxing to fly. I now look forward to building the sport wing - it will be my first aileron experience and I can't wait to try it!
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Old Jan 03, 2005, 03:40 PM
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Joined Mar 2004
5,237 Posts
Great thread! Thanks so much!! And good on ya for the flight! BTW, what is your AUW on the bird? And as an aside, while the rear wheel looks heavy, that looks like the way to go - and I suspect had you put the servos in the right spot (further forward) your COG/weight issue might not have been as bad. Enough of this playing with glue/contact cement etc.; guess I better order a couple now, eh?

Tom
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Old Jan 03, 2005, 04:03 PM
2 Mistakes Downwind
ToyBoy's Avatar
Portland, OR
Joined Nov 2004
414 Posts
Thanks Tom!

Yes, the position of the servos no doubt added to my CG problem. Actually I'm considering remounting them right up near the rear of the wing for that reason. Anything I can do to get the CG right without adding weight is good, and ideally I'd like to keep the battery pack in the hole I made for it.

I don't know the AUW yet as I don't have any scales, but I have some on the way, so stay tuned and I'll let you know how heavy she is. My scales should arrive this week. I'll also weigh the tailwheel brackets. Then I'll decide whether to ditch the steerable or not.

I certainly recommend this plane. I'm even thinking of getting a second one so that I can have one to fly for fun and keep this one as a dedicated AP ship.

Murray
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Old Jan 03, 2005, 05:40 PM
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Newark Ohio
Joined Sep 2001
573 Posts
I got mine as an AP ship more or less. But sometimes I like to fly something that does not need constant attention to keep in the air.

I dont think a little extra weight will hurt this plane too much, it's not as if we want vertical performance ya know. I will need to add weight also, but I moved the landing gear toward the front and I will see how that did here in a little bit.
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Old Jan 04, 2005, 02:32 AM
2 Mistakes Downwind
ToyBoy's Avatar
Portland, OR
Joined Nov 2004
414 Posts
It sure can lift some weight. Mine flies quite comfortably carrying a MM camera mount, a Nikon 3700, two extra servos, the heavy tail gear, and a battery pack that's probably about 40% heavier than the recommended pack and also one cell less, meaning lower thrust!

Hmmm... with a brushless motor, lipos and no landing gear, this plane probably would go almost vertical.
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Old Jan 17, 2005, 10:19 PM
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Arlington,Texas
Joined Jan 2005
2,239 Posts
I just finished reading your entire write up on the building of the Magpie. I too am contemplating the Magpie as my first build. I think by following the procedures you did will help me with my build. Congrats on the maiden flight and keep us posted on any new tips you might come up with.
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