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HelicopterAerial Photography and Video › Flying Bowling Ball
12-01-2007 06:46 PM  10 years agoPost 1
trackhead

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utah

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Retired the "Flying Pumpkin" for a "Flying Bowling Ball". Needed more room for some gadgetry inside, including roll stablization, downlink, receiver.

Shown here without pan gearing. Waiting for Mr. Postman to deliver that. G10 frame, Lexan bowling ball.

Not sure of the weight, but the little crappo T-rex handles it just fine. My camera will be happily blocked from the sun and flying snow at launch. As will be the receiver and downlink.

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12-01-2007 07:25 PM  10 years agoPost 2
46Taylorcraft

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AZ

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looks good but I gotta think that thing is getting to be pretty heavy these days.... no?

what size blades you running?

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12-01-2007 07:27 PM  10 years agoPost 3
Envision

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MI

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Where did you find the "lexan bowling ball"?

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12-01-2007 07:27 PM  10 years agoPost 4
trackhead

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utah

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DJ,

It's still far lighter than the Askman mount. I'll weigh the mount and see.....but it's very light with the thin G10.

Still running 600's. Plenty of power.

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12-01-2007 07:58 PM  10 years agoPost 5
rerazor

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Mich.

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Whats your total AUW and what size blades are you running?

I can't believe the Hunter Orange Pumpkin has reached its end.

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12-01-2007 08:18 PM  10 years agoPost 6
46Taylorcraft

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AZ

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me thinks you need a taller landing gear

I use Vario Benize gear on all my ships. Tall, strong, and wide... but slightly heavier than stock

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12-01-2007 09:29 PM  10 years agoPost 7
trackhead

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utah

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DJ,

Yeah, I am getting some taller gear.

Weighed the mount with all servos, battery, downlink, receiver, etc.
Weighs 32 oz. on the post office scale. Camera is about 17oz.

Even with all the extra junk, it's still significanlty lighter than the Askman or AF mounts, granted it's not 360.

It's also removable, so I can fit the heli in the carrying case while skiing.

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12-01-2007 11:34 PM  10 years agoPost 8
46Taylorcraft

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AZ

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that's not too heavy at all. can't wait to see more video!

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12-01-2007 11:50 PM  10 years agoPost 9
monterey_tip

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Monterey, Ca - USA

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Looks great. I'd second the taller landing gear. It can't be fun dragging your balls in the snow.

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12-02-2007 01:07 AM  10 years agoPost 10
Dakine

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OC, Commifornia

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I'd say, if you could land that thing safely, do not go with taller landing gears. You will get vibration through the taller gears. With a soft landing, you would not damage the sphere. Just a suggestion.

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12-02-2007 01:17 AM  10 years agoPost 11
kookboy

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Vancouver, BC

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Nice track.

Will you keep it jet black or paint it pumpkin orange ?

Jesse

... But honey it was only $$$

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12-02-2007 01:40 AM  10 years agoPost 12
trackhead

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utah

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Black, the orange didn't help with visibility against the sky.

The lens of the camera will be within the ball, so it should help with lens flare and snow flying around hitting the lens. That was my intention.

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12-02-2007 03:29 AM  10 years agoPost 13
jascamera

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san francisco, ca

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Trackhead,

Can try using four 1" spacer between skid and heli frame, you can find them in Home depot, come in either nylon, or aluminum. I seen other use this method for a gasser to raise the heli.

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12-02-2007 07:05 AM  10 years agoPost 14
Brady Longmore

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Idaho Falls, ID

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DAKINE:

Please explain why taller landing gear can provide vibrations. I'm having some problems that popped up after going with taller gear.

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12-02-2007 07:14 AM  10 years agoPost 15
jascamera

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san francisco, ca

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Hey, TrackHead,

I see you still using the Align BEC, is that the stock 3amp one, or upgrade 6 amp one. How long have you had it? I just setted up my 600 and first that I want to replace is the BEC, I have heard some problems with it.

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12-02-2007 07:55 AM  10 years agoPost 16
trackhead

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utah

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Brady,

I think it's because of the physics of it being further away from the heli. That sort of thing.

Jas,

All stock, except ESC.

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12-02-2007 05:11 PM  10 years agoPost 17
eric_b

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Denver, CO, USA

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Black, the orange didn't help with visibility against the sky.
Really?? I would think orange would be much better.
Please explain why taller landing gear can provide vibrations. I'm having some problems that popped up after going with taller gear.
All structures have natural frequencies, meaning that at some frequency of vibrational input, the structure will vibrate. When you change the configuration of the landing gear, it changes the resonant frequency(ies) of the helicopter. Adding structure (mass) farther from the CG will allow the heli to be more affected by lower frequencies (like the kind present with out models: ie: engine and rotor vibs)and induce harmonic vibration. Ground resonance can occur with all helicopters (models or full-size) (edit: that have undampened lead/lag hinging) and comes into play when the heli is close to taking off, or just after landing. During this time the heli is partially supported by the rotor system and partially supported by the ground. Also, the rotor rpm is usually changing, and this causes lead/lag movement of the rotor blades. Harmonic resonance (vibration) develops from the lead/lag imbalance, depending on a combination of the blade speed, blade lead/lag swing, engine/drive train/main rotor/tail rotor vibration, base frequencies of the structure, and dampening characteristics of the surface (dirt vs. pavement). If left in this condition, the resonance can increase to the point that the heli will tip over, boom strike or otherwise break apart. Here is a really good video of ground resonance testing with a Chinook:
http://www.youtube.com/watch?v=RihcJR0zvfM
A different view of same:
http://www.youtube.com/watch?v=0GEj69NANc8

By changing the landing gear to allow more ground clearance, you potentially decrease the rigidity of the landing gear, and allow a longer moment arm(s) for the resonance vibration to act upon (the physics of having the CG of the machine farther from the supporting surface). In other words, it is more affected by lower frequency harmonics. Be VERY careful when testing a new tall landing gear setup. If you experience ground resonance, you need to act quickly to move the heli out of that situation by either sharply reducing power or taking off into a hover. Once airborne, these vibrations disappear (provided the long landing gear structure is rigid enough or vibration isolated to reject dynamic flight vibs). Sometimes, bumping the throttle, changing blade rpm, or moving from a hard suface landing pad to grass/dirt, or changing the blade grip holding force (usually tighter) is sufficient to interrupt the ground resonance from attenuating. But be careful, helis can blow apart before they even leave the ground if ground resonance is severe.

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12-02-2007 07:45 PM  10 years agoPost 18
monterey_tip

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Monterey, Ca - USA

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Wow, Eric_b ...great info...super technical...my brain hurts.

This is more my speed:
Brady,

I think it's because of the physics of it being further away from the heli. That sort of thing.
I'm surprised too about the black showing up the same as bright orange.

Tip

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12-02-2007 08:02 PM  10 years agoPost 19
Dakine

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OC, Commifornia

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Eric,

You took the words out of my mouth! That's how I was going to reply.

Anyway, my short, cut to the chase suggestion again: You will increase vibration in your system with taller landing gear. That's the extent of my engineering theory .

If you can land softly with your current gear, keep them the way they are. And, do not go for the cool proportional (heli) look with taller gears, you would induce vibration in your system. It's about getting the smooth shot, not the cool looks.

However, in a forced auto, you'd be $hit out of luck with shorter gears (damaging your ball). And, we all know that damaging our 'balls' hurt! It's a give and take.

Good luck.

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12-02-2007 09:32 PM  10 years agoPost 20
Brady Longmore

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Idaho Falls, ID

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Eric:

Thanks for clearing that up and being so articulate about it. I gather though, that once airborne the vibes created by taller landing gear should subside...once you get clear of the ground effect?

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HelicopterAerial Photography and Video › Flying Bowling Ball
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