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 Post subject: RC Today Show 138: Bert and Suzi Kammerer
PostPosted: Fri Sep 12, 2014 4:56 pm 
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In this episode: Bobby, Chris, and Alex are joined by Bert and Suzi Kammerer for this show. It's been a long time since we've talked with Bert, so we've got some catching up to do. Tune in!

http://wp.me/p2wnPS-uF

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 Post subject: Re: RC Today Show 138: Bert and Suzi Kammerer
PostPosted: Fri Sep 12, 2014 5:52 pm 
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Hey the link to ◾Larry’s Wheelchair PayPal doesn't work. Help those of us that wish to help.


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 Post subject: Re: RC Today Show 138: Bert and Suzi Kammerer
PostPosted: Fri Sep 12, 2014 7:31 pm 
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It's smsila@sbcglobal.net. Not sure why the link didn't work, so I just changed it to plain text in the show notes.

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 Post subject: Re: RC Today Show 138: Bert and Suzi Kammerer
PostPosted: Mon Sep 15, 2014 8:46 am 
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Great show guys! That was an awesome talk about working in the industry. Great conversation!

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 Post subject: Re: RC Today Show 138: Bert and Suzi Kammerer
PostPosted: Mon Sep 15, 2014 8:53 am 
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I have a term for Alex to add to his McDougal list: McThud. That would cover the case Bert talked about where the heli didn't bounce.

I'm still confused as to how you get the head to overspeed. Is it just a matter of loading it with pitch and then suddenly going to zero pitch?

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 Post subject: Re: RC Today Show 138: Bert and Suzi Kammerer
PostPosted: Mon Sep 15, 2014 8:59 am 
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TheBum wrote:
McThud
:rolling

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 Post subject: Re: RC Today Show 138: Bert and Suzi Kammerer
PostPosted: Mon Sep 15, 2014 9:21 am 
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TheBum wrote:
I'm still confused as to how you get the head to overspeed. Is it just a matter of loading it with pitch and then suddenly going to zero pitch?
Actually think of it more like doing an auto with the power still on. You use gravity and negative pitch to overspeed the rotor system.

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 Post subject: Re: RC Today Show 138: Bert and Suzi Kammerer
PostPosted: Mon Sep 15, 2014 9:28 am 
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That was a great Show

Bert and Suzi come across as real nice down to earth people.

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 Post subject: Re: RC Today Show 138: Bert and Suzi Kammerer
PostPosted: Mon Sep 15, 2014 9:37 am 
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JustPlaneChris wrote:
TheBum wrote:
I'm still confused as to how you get the head to overspeed. Is it just a matter of loading it with pitch and then suddenly going to zero pitch?
Actually think of it more like doing an auto with the power still on. You use gravity and negative pitch to overspeed the rotor system.

Ah, so pulling out of the maneuver to get the overspeed is the same as a flare. That would explain the high-speed flight at the beginning.

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 Post subject: Re: RC Today Show 138: Bert and Suzi Kammerer
PostPosted: Mon Sep 15, 2014 10:19 am 
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You got it Alan. Let me see if I can put in into math terms:

Lets say you are descending at full negative pitch (leaving other factors out for the example).

2000 rpm headspeed and -12° of negative pitch
@45" diameter of a Goblin 500
45" x π = 141.37" circumference of the disk
tangent 12° x 141.37" ≈ 30" per rotation of the blade

30"/ rot × 2000 rot/min × 1 mile/63,600" × 60 min/hr ≈ 57 mph

Descending speed of around 57 mph would of course cause a 57 mile per hour wind blowing over the disk. Now while descending decrease the pitch of your blades to around 3°. Viewing the math you can now easily see how the rotation of the head must increase to account for the decreased pitch.

57 miles/hr × 1 hr/60 min × 63.360"/1 mile × 1 rot/7.5" ≈ 8025 rot/min

Theoretically your headspeed would be around 8000 rpm @ 3° in order to travel at 57 mph.

To simplify just imagine: ° of pitch X headspeed = descent speed.
If descent speed remains equal and you decrease pitch, your headspeed should increase.

This is for everyone but Chris' Mini Protos that the one way bearing doesn't work on. :tongue

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