The "MINIFLASH"

From Mountain Models

This page was last edited / updated on December 20th, 2002; Thanks for visiting!!






It's winter flying season as these photos are taken, so my MINIFLASH is on skis, on longer-than-stock landing gear legs. I did most of the 'artwort' on the bare wood structure of the fuselage, then covered it with clear Doculam material. The wing is covered with Ultracote light transparent film. The Flourescent Yellow Ultracote was added to the top surface of the wing to add extra aircraft 'attitude definition'- this one is set up with a fast roll rate & radical control throws, taking advantage of the Exponentials on my computer transmitter to keep it handling smoothly at modest control stick deflections.



The power system is a GWS EPS300C in the "D" gear ratio (6.6 to 1) with advanced timing, turning a GWS EP1280 prop in our thinner air up here above 9000 feet. It flys on an 8 cell 600AE or 1000mAH NiMH battery pack- and it flies very impressively- fully 3D performance! At about 18 ounces on skis, it literally jumps off the snow in less than ten feet, and can climb vertically. I had to install longer landing gear legs that those that were provided in the kit, in order to have prop clearance from the ground / snow; while I was at it, I extended the gear legs forward and out wider, for even better ground handling stability.



In the photo above you can see the radio receiver's black antenna wire routed back and forth over the top of the rear fuselage, so that there is no excess length extending; the end is routed up the leading edge of the vertical stabilizer. (A HITEC 555 receiver is being used at this time.)







Getting the battery far enough forward to balance properly so that it will fly smoothly was a bit of a challenge; I initially set it up to balance 3/4" behind the spar, as recomnmended in the kit instruction booklet. This was as far forward as I could shift the batteries in the available space, without resorting to butchering some of the interior structure. This unfortunately led to some really strange handling characteristics... the balance needed to be moved forward substantially more. (Without the longer landing gear legs, it would have been even worse!)

Wierd things were happening with the pitch axis stability (or lack therof...)

In desperation, I removed the Horizontal Stabilizer and Elevator and made a new place to mount them 11/16" higher, up out of the possible wing shadow. I also removed the 'counterbalance' sections from the outer ends of the elevator and glued them to the Horizontal Stabilizer. I installed a .040 diameter music wire tailskid while I had everything tore apart, too, since the 1/32" material provided with the kit was too light & wimpy to carry the weight of this plane.

But these measures still did not help much with the wierd handling characteristics... !!@&?!??**@!!

Another experienced flyer sugested moving the balance even farther forward- that it looked & handled like it really needed it. So it was time to get ruthless, and start clearing enough bulkhead material to allow placing the battery even farther forward. (I considered trying to extend the hatch / canopy farther forward too, to give better battery handling access, but decided not to do that much right away.

I ended up enlarging the opening in the bulkhead at the leading edge of the wing, and trimming some other wood from the rear motor mount cross member, so that I could install a new 1/16" battery mounting 'deck plate'. My 8 cell 600AE battery pack is in a 2x2x2 'cube' configuration, and now slides in on the new dect all the way forward against the rear end of the motor. I use a velcro-attached balsa battery 'retainer' block at the rear end of the battery pack to keep it from shifting in flight.

This brought the balance forward enough, to a point about 3/8" behind the lower wing spar. This eliminated a lot of the wierd handling, where I could really start to 'tease the weasel' - and I'm finally grinning & crowding the performance envelope farther each time I fly this bird.



What's next in 'optimizing' the handling of this design? I'm still unhappy with the landing gear's tendancy to rotate repeatedly- there are two single pieces of wire plugged into two holes, and they're somehow expected to be simply held in their proper orientation by glue. It may sound OK in theory, but in practice it's just not working- maybe because I'm flying here in the mountains, landing in grass, gravel, or landing on snow with the skis. Not all landing surfaces are as smooth as the groomed surfaces that city flyers may be able to enjoy, so I'm working on a design for some one-piece landing gear that will deal with the rude realities of 'Mountain Flying".

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