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Ace Grasshopper flies again!

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Old 05-22-2014, 07:29 PM
  #1
dabigboy
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Default Ace Grasshopper flies again!

Got another project off the bench a few weeks ago...it's been too windy or rainy to fly here in OK (or I've been busy), but last night I finally got out to the local park and put the Grasshopper up for the first time in nearly 20 years. This is the first RC model I "built", when I was 12. With a big RX battery, standard servos, and a little (unreliable) Cox .049 for power, it never really flew right. The best I could ever do was about 20 seconds of low-altitude, high-speed circuits before the engine sputtered and I made a semi-crash landing.

After countless hours of crashing/landing/skidding/cartwheeling through soybean fields and a gravel driveway, and years of abuse/neglect via multiple moves and often poor storage conditions, the Grasshopper had been reduced to a fuel-soaked fuselage with no gear, no motor, no vertical stabilizer or rudder, no elevator, and a completely gutted radio compartment. I actually had serious doubts about putting a flyable rig together, but it worked out.

The "revived" Grasshopper has micro servos, less covering (I skipped covering the bottom of the outer wing panels), and an Emax CF2812 1534kv outrunner for power, on a 3s lipo. It still weighs a ton...I had thoughts of cutting lightening holes in the plywood "box" fuselage, but it's so fuel-soaked that I decided to leave it as-is over structural concerns.......

I think I over-powered it! I used full power for takeoff, and nearly pulled the wings off! The plane zipped crazily along for a few seconds, then decided to do some snap rolls...?? This concluded with a split-S...the little foam wing bent SO FAR that I was almost sure I was about to lose the plane, in fact I thought I had broken the wing in half. But a power reduction and a light touch on the controls immediately put the plane into something that resembled controlled flight. I ended up using less than half power for most of the flight, except for a few *ridiculous* climbs and high-speed bursts.

The lipo lasted FOREVER....it finally got dark and I landed with plenty of juice left. I could probably go with a much lighter 2s lipo and save some weight. Though I must say, it was pretty cool to do a low pass at "normal" speeds, then hit the throttle and see the plane obviously and instantly shoot forward....not that the Grasshopper handles high speed very well, but it's whetted my appetite for a much faster model in this size.

I think it's tail heavy....I moved the battery forward a bit after the first couple minutes of flight. It helped. I think a little more forward CG would further improve things.

Overall, very unstable in the air. Interestingly, it spins incredibly well (especially to the left...hmmm). This is DEFINITELY not a beginner's plane....but it's interesting, nonetheless. I really did this more for the nostalgia than to make a good flier, as I am aware of the Grasshopper's less-than-stellar reputation. It was cool to see it fly after all these years....I had never seen it fly as much as it did last night!

Pics of course...note that the old "Grasshopper" decal was actually salvaged! It peeled right off the old covering and was still plenty sticky, just a little yellowed with age.



I might just hang this in the shop and stick the motor in something that goes fast, we'll see. At the very least, I FINALLY "conquered" this little guy and got it to stay in the air, despite its objections.
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Old 06-16-2014, 04:53 PM
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dabigboy
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Not sure if anyone is interested in this old ugly design, but I thought I would post an update on the flight characteristics: it's an odd one! Good news, moving the battery forward a bit did tame the handling down nicely. I've had a chance to wring it out a bit more and have found some interesting behaviors:

- If you snap-roll, then neutralize rudder and give full-down elevator, the plane continues to rotate about the yaw axis quite rapidly for a second or so, while barely moving through the air. I'm assuming the nearly non-existent side area allows the inertia of the plane to keep it spinning once rudder is released, and slows the plane's return to a normal flight path. Gave me bit of a scare the first time I did it, really looks like you've lost control and the plane is just falling out of the sky.

- It seems to be very tolerant to high-speed flight, despite the fact that going fast makes it wiggle and bob and bounce all over the place (especially in wind), and the tailfeathers twist and flutter a bit on that tiny, flexible tail boom (carbon fiber). It shakes around a lot in turbulence too, but manages to remain pretty controllable.

- IT FLIES INVERTED. I've never seen a polyhedral, rudder/elevator design that does anything like sustained inverted flight. I'm even able to make decent turns, and there is a bit of down-elevator available for climbing, and for recovering from shallow dives.

- Those foam wings VISIBLY flex, A LOT! Good thing I added extra packing tape reinforcement. :P

All in all, a very odd plane to fly. I think I will keep it airworthy just for the novelty of it!
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Old 06-18-2014, 05:20 PM
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blvdbuzzard
 
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I built one for my nephews to learn to fly. After I got them setup to start the engine off they went, fly, crash, repair, repeat. They spent the summer flying this thing. The went through 4 engines and 2 gallons of fuel.

I may have the plans laying around. Would be nice with modern 9g servos, 1000mah lipos, brushless motor.

Buzz.
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