[NSRCA-discussion] Electric props

Fri Jun 23 11:01:28 AKDT 2006

Stuart

The "W" props are also quite a bit heavier than the regular E versions.

Earl

----- Original Message ----- 
From: "Stuart Chale" <schale at optonline.net>
To: "'NSRCA Mailing List'" <nsrca-discussion at lists.nsrca.org>
Sent: Friday, June 23, 2006 11:30 AM
Subject: Re: [NSRCA-discussion] Electric props

> Thanks Earl that was helpful.
> Not sure of the weight of the 21 inch props but the 20 x 15 is over 20 gms
> less than the 22 x 12 and puts me under 5 kilos :)
> Stuart
>
> -----Original Message-----
> From: nsrca-discussion-bounces at lists.nsrca.org
> [mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of Earl Haury
> Sent: Friday, June 23, 2006 11:16 AM
> To: NSRCA Mailing List
> Subject: Re: [NSRCA-discussion] Electric props
>
> Stuart
>
> For a given voltage the motors we use will run (nominally) the same rpm
> within a reasonable range of props (load) with the current flow increasing 
> /
>
> decreasing with load. However - the catch 22 - as more or less current is
> drawn from the batteries the voltage will vary accordingly (batteries 
> aren't
>
> a constant voltage source). So while a charged pack is nominally 42v no
> load - voltage  will be considerably less with load, and motor rpm will 
> vary
>
> accordingly. So max "throttle" rpm will be higher with smaller props than
> with larger, as the lighter load results in higher volts.
>
> With the 14  Hacker any of the props you list will work - data I've
> collected indicate that the 20x15, 21x14, 21x13W, & 22x12 run about the 
> same
>
> (volts / amps / rpm) with different flight performance for each - you'll
> need to see which works best for you. (I suggest trying the 21x14 first.)
>
> I've observed that folks switching from glow to E and using the lower 
> pitch
> (10 - 12) props tend to use a lot of their battery capacity for a flight 
> in
> an effort to attain the speed they're used to with glow (flying E at max
> throttle a lot). For this reason it's probably better to start with the
> higher pitch props and work back (or simply use the stick) for slower 
> speeds
>
> as one gets used to E performance.
>
> Earl
>
>
> ----- Original Message ----- 
> From: "Stuart Chale" <schale at optonline.net>
> To: "'NSRCA Mailing List'" <nsrca-discussion at lists.nsrca.org>
> Sent: Friday, June 23, 2006 6:44 AM
> Subject: Re: [NSRCA-discussion] Electric props
>
>
>>I am still a little vague on some of the electric stuff which is why I am
>> starting with a known combination.
>> The motor is the standard Hacker C50 14 XL with 6.7/1 gear box.  Hacker
>> acro
>> 90 speed controller. I am going to run Falcon F3A packs.
>> The plane is an E- Pinnacle and all up weight with the Falcon packs is 5
>> kilos.  Actually about 5010 gms right now but that is a different tale :)
>> The Falcon packs are about 5 oz heavier than the TP packs.
>> I am starting with the APC 22 x 12 as that is what most seem to use.
>>
>> Putting on a bigger prop causing it to draw more current makes sense.  As
>> I
>> understand it the motor wants to spin a set rpm based on the input
>> voltage.
>>
>> What about a smaller prop?  Does it still turn the same RPM at less
>> current
>> and thrust?
>> How do I determine which smaller diam/higher pitch prop is too much for
>> the
>> system?  I am sure that some of you have already tried this?
>>
>> Do the calculators really help?
>> Dave, which one?
>> Pocono?  No haven't even flown the plane yet :)  You will not see me at a
>> contest until I have a good bit of practice.  I have to get my son flying
>> yet.  Maybe Sayre?
>>
>> Stuart
>>
>>
>> -----Original Message-----
>> From: nsrca-discussion-bounces at lists.nsrca.org
>> [mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of Larry
>> Sent: Friday, June 23, 2006 2:36 AM
>> To: NSRCA Mailing List
>> Subject: Re: [NSRCA-discussion] Electric props
>>
>> Hi Stuart,
>>
>> We need more info. Unfortunately, electrics have more variables than IC
>> setups.
>>
>> What plane is this going into? Specifically what is the all up weight of
>> the
>>
>> plane going to be and how much power do you think you need?
>>
>> What size battery pack are you going to run - ?S?P and what capacity?
>>
>> Also, what gear ratio?
>>
>>
>> To start answering your question - every item in an electric power system
>> has an effect on power output and amp draw.
>>
>> Larger diameter/higher pitch props will draw more current and produce 
>> more
>> power than smaller ones. Assuming all other variables stay the same.
>>
>> However, you cant just arbitrarily increase/decrease the prop size. The
>> total power system has to work together. The batteries need to be able to
>> sustain the load and the motor needs to be able to handle the power
>> output.
>>
>>
>> Larry
>>
>>
>> ----- Original Message ----- 
>> From: "Stuart Chale" <schale at optonline.net>
>> To: "'NSRCA Mailing List'" <nsrca-discussion at lists.nsrca.org>
>> Sent: Thursday, June 22, 2006 9:30 PM
>> Subject: [NSRCA-discussion] Electric props
>>
>>
>>> Rather than redo tests that others have done I thought I would question
>>> the
>>> group regarding the different sized electric props available.  It seems
>>> like
>>> there should be a much better consistency and less variability between
>>> different electric motors compared to different IC setups.
>>> I am going to run the Hacker C50 14 XL (not comp model) with the 90 amp
>>> Acro
>>> speed controller.  Seems as if most people are running the 22x12 APC E
>>> prop.
>>>
>>>
>>> Below is a list of potential props I found on the APC web site.
>>> If you have tried any of them and found a reproducible difference from
>>> the
>>> 22x12 I, and I am sure others would like your thoughts.  If any of the
>>> props
>>> are too much for the setup please let me know.  (No reason to waste 
>>> money
>>> on
>>> an unusable prop)
>>> Hat happens when you run less of a prop say the 20 x 11?  Does the RPM
>>> stay
>>> the same?  Will the current usually go up or down?
>>> These seem to be the possible choices from APC
>>>
>>> 20 x 11
>>> 20 x 13
>>> 21 x 14
>>> 20 x 15
>>> 22 x 10 ( I would suspect a slower flight speed)?
>>> 20 x 12 wide
>>> 21 x 12 wide
>>> 21 x 13 wide
>>> 20.5 x 12 wide
>>>
>>>
>>> Thanks
>>> Stuart Chale
>>>
>>> E-Pinnacle should be ready to fly this weekend.
>>>
>>>
>>> _______________________________________________
>>> NSRCA-discussion mailing list
>>> NSRCA-discussion at lists.nsrca.org
>>> http://lists.nsrca.org/mailman/listinfo/nsrca-discussion
>>>
>>
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