|Aug 08, 2009, 09:40 PM|
bad day at the field is better than a good day at work ;)
Last week I suffered two casualties: my hacker fai carbon motor melted, and due to some new programming, my bandit failed to power up upon launch.
Bandit is a 2kw hog, so when the spinner hit the runway, my heart sank. Thankfully the motor mount caved in, and the spinner only took a minor beating.
Plane 1: Bandit
New firewall made of c10 using the dbox method: cut out an overly large circle, put a hole in the center, run a rubber dremel drum through the hole, fire up the dremel, and grind away at the g10 against a file (make sure no one else is at home, it is LOUD). I think it came out pretty good, I used a motor mount that came with the motor (hyperion zs3025... WAY under-rated at 105 amps, I am pulling over 180, but may end up changing the three leads from the motor, as they are a tad to thin to handle this amperage), then I ground the cooling holes to match the inlets of the motor. Finally, I ca'd two steel washers around each mounting hole on the motor: this allows some of the air that comes from the turbo spinner to circulate around the motor (i.e. small gap between front of motor and motor mount).
Now, the spinner was snazy white rfm. It cracked when the bandit ate it. I primed it, and then sanded, and primed,.... painted red, then sanded, painted red,.... then, I applied krylon crystal glaze triple thick clear coat.... IT ATE ALL MY PAINT! Sanded the rfm pinner to the bare carbon, and then sprayed that with the clear coat... looks... awesome, no pictures this round, but I promise some to come.
Note: the glue used for the firewall is finishing resin mixed with carbon: the carbon is simply minced tow
Edit: Around the screws is neosporine works as well as vasoline to prevent epoxy from sticking!
|Aug 08, 2009, 09:46 PM|
Plane 2: Fredy
The Fredy housed the melted carbon hacker. The motor was a 7 turn (roughly a b40 7m). I opted not to mail the motor in (at least just not yet), as it would be $15 only to learn how toasted the motor is. One phone call to David + ZB over at esprit, and 3 days later (on the opposite coast), I had a neu 1012 2d in my hands. This little monster should hold up to more stress than the hacker... unde 10% heavier (trivial) and a tad longer. I installed a kontronik 5.2 (GREAT boxes, way smaller than the neu's if you need to reduce a b40 or 11xx series motor), and within 1 second of testing, it was pulling all of amps on a 12.8x13
Loose pinion. I had soldered it on, but apparently I need to switch to a higher silver content for these things. A little locktite green, and the 12.8x13 pulled under 70 amps on the rfm 12.8x13.... GREAT NEWS because the 14.5x14 may be just the ticket... think balco for Barry
|Aug 08, 2009, 10:00 PM|
Plane 3: Enigma
Went to the field yesterday, as I gutted my enigma wing and replaced all the servos (ds09a on ailerons and ds095 on flaps). MUCH less slop (still a tad given the horns on the surfaces are so low... I bought the plane used). The crazy part is, the original builder had used the flaps on a y-harness, the the flap horn install is non-symmetric.... not a huge problem, but a tad frustrating (the nsew servos are entirely flush, but I'll have to buy 2 sets of covers gicen I need two "lefts" for the flaps )
Ok, so a nice landing, but a thud final (from say 6 inches off the ground) caused the elevator servo to stop working. The Hyperion servo had bottomed out (lost it's bottom). I have NOT been epoxying these in, but rather have been screwing them into wood casings I built. Seems epoxy may be the right way to do it to prevent this from happening. FWIW, I applied presure and the case snapped back together, and witheld all the the abuse I could throw at it from the ground... seems fine
Final flight was a nightmare. new prop (16x18) is a thrust MONSTER, makes the launch hairy (I'm working on a launch program in the radio that gives delayed power-up for launch, and full power off-launch... sounds easy, but x9303...). Well, motor mount came loose, and the cc180 I had in there started to do the twist. I got lucky and the I think the hyperion rdu between the esc and the lipo prevented the lipo leads from making contact and shorting. But... I had to wire a new controller on there, and then redo the motor mount... not a great sat. but here goes:
First up is the esc -> motor connection, pretty self explanatory from the pics
|Aug 08, 2009, 10:01 PM|
Next up is the motor mount itself. I used a drum sander on the dremel to clean all traced of the previous install, and then a steel brush-disc attachment for the spots that were close to the enigma lip. I then used a tiny cutter to rough up the inside of the nose where the mount will go.
The original motor mount was pretty slick... a few carbon disks adhered togeher. I like it, except it has a smooth edge... nothing a dremel reinforced wheel cant mar (see picks). I then wrapped the motor in saran-wrap, the cat thought it was kinky and started doing this (see pic). A few cat-snacks later, and it was back to business. Pulled out a napa valley red (please... after cooking, thi sis the best use for this wine (these folks must have bought a case, they bring the same bottle every time they come for dinner (I make some pretty mean tenderloins )).
Lynched the plane with electrical cord (even twine had the plane slipping around). Likewise on the red. A few rubber bands, and then the great wait... once it cures, I may put some more slime in a straw and distribute it from the inside of the fuse via the hole in the motor mount... will be a challenge.
Ok, leaving town for 3 days, just enough time for a full cure, need to run back in and repair the lipo pack that ate it in the enigma, that way when I get back to ca, I can finish the mount, and then go practice flying in circles
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