[NSRCA-discussion] More electric newbie questions

[colin chariandy]

I'm still trying to get my head around windmilling, low idle and higher idle 
being almost the same for downline speed.

I would have thought (from traditional magnetics theory) that there should be 
some torque (synchronization) derived from the rotating field and the rotating 
magnets to resist speeding up. Unless the rotating feild is too weak at low RPM 
and once out of sync the speed increases with little resistance. Thus the 
question....is it better to have a higher idle (stronger field)?

I am assuming that at low RPM both the PWM and the field voltage are lower than 
at higher RPM.

The problem is that theory and actual test data often don't go hand in 
hand....and not many clock the speed of their planes.




________________________________
From: Dave Lockhart <DaveL322 at comcast.net>
To: General pattern discussion <nsrca-discussion at lists.nsrca.org>
Sent: Mon, June 20, 2011 3:25:11 PM
Subject: Re: [NSRCA-discussion] More electric newbie questions


Ooopsss…..I meant to respond to your 1), 2), and 4) scenarios……
 
I haven’t flown the 3) med brake setting on the Jeti…..but yes, it is possible 
to have too much brake, and then you will have a faster downline speed than just 
a windmilling prop.

Dave
 
From:nsrca-discussion-bounces at lists.nsrca.org 
[mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of colin chariandy
Sent: Monday, June 20, 2011 3:20 PM
To: General pattern discussion
Subject: Re: [NSRCA-discussion] More electric newbie questions
 
Dave....so you are saying:
 
No brake (regardless of idle or windmilling) - approx the same speed on 
downlines.
Too much brake - faster than idle/no brake?
 
Colin
 

________________________________

From:Dave Lockhart <DaveL322 at comcast.net>
To: General pattern discussion <nsrca-discussion at lists.nsrca.org>
Sent: Mon, June 20, 2011 1:00:02 PM
Subject: Re: [NSRCA-discussion] More electric newbie questions
Using Castle stuff….
 
1) and 2)     definitely not…..the idle RPM is not governed, and will wind up 
substantially in downlines, RPM will be the same at the end of the downline 
whether starting at low idle or high idle.  I’m not aware of any different 
behavior on other brands of ESCs.
3)  definitely not……wind up in downlines is virtually indistinguishable from 
using low idle.
 
Depending on just how many braking parameters you can adjust (which does vary 
between Castle, Jeti, Schulze, YGE), it is possible to have too much brake…..at 
a point, the downlines will become faster again when the prop disc is spinning 
too slowly.  I’ve been told that the ideal idle RPM (for maximum braking) can be 
calculated, but I don’t know anyone that has done this (and I certainly don’t 
have the knowledge to run the numbers).
 
Regards,
 
Dave
 
From:nsrca-discussion-bounces at lists.nsrca.org 
[mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of colin chariandy
Sent: Monday, June 20, 2011 11:44 AM
To: NSRCA Mailing List
Subject: [NSRCA-discussion] More electric newbie questions
 
I can't find any definative reading on this so I have to ask the group.
 
Which configuration provides the most braking on downlines and approach for 
landing  (Jeti 90 + evo 30-10) :
 
1) Lowest possible idle
2) Windmilling prop
3) Jeti Med brake
4) Slighlty higher idle
 
My testing has not been conclusive....just not enough data.
 
Thanks
Colin.
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