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HelicopterBergen R/C Helicopters › Industrial Twin pitch range
11-29-2005 08:50 PM  12 years agoPost 1
RV-4Mike

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San Diego, Ca.

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We recently acquired a Twin setup for autonomous flight. I didnt get a twin manual with the heli. We had a minor oops with it last week that resulted in a hard landing. I'm putting it back together now and notice it has an extremely limited pitch range - looks to be only 8 degrees. The heli was setup with max pitch at +10 and min pitch at +2. Makes for a pretty interesting auto with an all up weight of 35 pounds.

Anyway, does this sound normal for the twin? The limit is due to hard mechanical stops so doesnt look like any way to increase without either grinding on the headblock or using a longer main shaft. Not looking for miracles, would just like to get min pitch to 0 or -1.

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11-29-2005 09:18 PM  12 years agoPost 2
Chris Bergen

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cassopolis, MI USA

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Which main shaft do you have in it? We currently offer 2 sizes and sounds like you have the short one. The long one will either have a third hole or a divot towards on end.

The pitch range is somewhat limited on the Twin (really no need for +10 -10 ), but you can normally get -4 to +10.

Chris D. Bergen

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11-30-2005 06:45 PM  12 years agoPost 3
RV-4Mike

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San Diego, Ca.

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Greg,

My Twin was setup the same way as my EB - per the EB manual the Bell pushrod from the swash goes to the long arm of the mixer and the Hiller pushrod from the seesaw goes to the short arm of the mixer. Are you saying this should be reversed on the Twin?

Chris,

I assumed that this was probably the case - that the main shaft is the same as the EB shaft? In that case because the Twin has a taller main gear the upper bearing block gets moved up? The range of motion of the swash is limited by the upper bearing block on the bottom end and the bottom of the head block at the upper end. A longer shaft would solve it so I'm assuming I have the short shaft. Would the extra hole/divot be at the bottom or top of the shaft (if it were there)?

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11-30-2005 06:48 PM  12 years agoPost 4
RV-4Mike

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San Diego, Ca.

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Also meant to mention, the company that integrates the UAV gear onto the heli suggests a minimum of +11 degrees on the top end. At the moment my pitch range is +3 to +11. That's all I can get.

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12-02-2005 02:22 PM  12 years agoPost 5
Chris Bergen

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cassopolis, MI USA

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The EB shaft is a standard one unless you have the Driven tail upgrade, which requires the longer main shaft and uses the hole or divot to secure the crown gear to the mainshaft.

The hole or divot should be towards the bottom of the mainshaft, roughly just above the main gear.

I'm not sure why the suggestion of at least 11 degrees. Even fully loaded the heli will hover at about 7-8 degrees and climbout with 10 or 11, why do you need more?

Either way, I'm fairly certain you have a standard shaft.

Chris D. Bergen

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12-02-2005 04:32 PM  12 years agoPost 6
RV-4Mike

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San Diego, Ca.

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Chris,

Thanks for the feedback. I'm certain that we have the short shaft as well. I need to order some parts soon so will order the long shaft and give that a try.

As for the 11 degrees, that's what the UAV manufacturer recommended. I'm assuming he recommended that due to the heli's weight. But I've found out that it doesnt appear to be necessary and we definitely need to get lower on the bottom end. So I've readjusted my pitch range to +9.5 to +1.5. Would still like to have more range but this is the best I can get currently and the heli is flying OK with this setup.

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HelicopterBergen R/C Helicopters › Industrial Twin pitch range
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