[NSRCA-discussion] Going Electric - Battery Questions

Fri Dec 7 17:09:40 AKST 2012

OK, so if my calculations are correct, a 10% difference in nitro amounts 
to a 0.14% difference in weight.  In a 20-oz tank of fuel, I can't think 
that will make a noticeable difference in overall aircraft weight or 
balance.  So, doing all thehigher math -- actually, since the fuel is 
going to fly, we must get into computational fluid dynamics!  ;-{) -- I 
calculate that 20 oz of 25% fuel weighs 0.96 oz more than a 20oz tank of 
14% nitro.  If my calcs are correct, that is hardly anything to write 
home about!!!

Phil Spelt, KCRC President
AMA 1294 Scientific Leader Member
SPA 177 Board Member
(865)435-1476v, (865)604-0541c

On 12/7/2012 8:17 PM, Dave Burton wrote:
>
> Actually it does! nitro is approx 9.4 lbs per gal,  methanol is approx 
> 6.7 lbs per gal.
>
> *From:* nsrca-discussion-bounces at lists.nsrca.org 
> [mailto:nsrca-discussion-bounces at lists.nsrca.org] *On Behalf Of *PhilS.
> *Sent:* Friday, December 07, 2012 7:45 PM
> *To:* General pattern discussion
> *Subject:* Re: [NSRCA-discussion] Going Electric - Battery Questions
>
> Sorry, Verne, more Nitro doesn't cost us more weight.  ;-{)
>
> Phil Spelt, KCRC President
> AMA 1294 Scientific Leader Member
> SPA 177 Board Member
> (865)435-1476v, (865)604-0541c
>
>
> On 12/7/2012 7:15 PM, Verne Koester wrote:
>
> Larry, 20C is 10% nitro, 40C is 40% nitro. Like nitro, more C is more 
> weight as well in most cases.
>
> I fly Masters with 20C batteries and have my throttle governed back to 
> make it easier to manage the excess power. I started last season with 
> 25C batteries and had to govern it back even more. Using 40C batteries 
> would be like sticking a YS 170 on a 110-size plane while probably 
> putting you over the weight limit.
>
> Verne
>
> *From:* nsrca-discussion-bounces at lists.nsrca.org 
> <mailto:nsrca-discussion-bounces at lists.nsrca.org> 
> [mailto:nsrca-discussion-bounces at lists.nsrca.org] *On Behalf Of *Larry 
> Diamond
> *Sent:* Friday, December 07, 2012 6:18 PM
> *To:* General pattern discussion
> *Subject:* Re: [NSRCA-discussion] Going Electric - Battery Questions
>
> Interesting point... I don't understand how changing from 20C to 40C 
> pack makes a difference using the same Motor and ESC combo. If it's 
> battery heat, my electronics background would tell me the pack is 
> probably being dicharged too deep. Not good for the life of a battery.
>
> I suspect the result of not changing the Motor/ESC and only changing 
> the battery will reult in a shorter battery life; and, over loading 
> the power plant which will probably result in damaging the ESC and/or 
> the Motor.
>
> I could be wrong, cause I really have no experience with electric 
> power set ups in planes. I just don't understand the logic going from 
> 20C to 40C and the result being "too hot for intermediate".
>
> It wouldn't surprise me to see Masters or FAI having a higher power 
> set up, like 3,500 to 4,000+ watts. Then depending on the max current 
> draw,  40C may make sense.
>
> My set up will be about 2,700 to 3,000 watts based on specs... It may 
> not be sufficient for Masters or FAI.
>
> Perhaps this will turn out to be a good constructive discussion for a 
> number of people like me, but I'm curious as to other opinions who 
> have practicle knowledge.
>
> Larry Diamond
>
> *From:* Patrick Harris <harris7148 at gmail.com 
> <mailto:harris7148 at gmail.com>>
> *To:* General pattern discussion <nsrca-discussion at lists.nsrca.org 
> <mailto:nsrca-discussion at lists.nsrca.org>>
> *Sent:* Friday, December 7, 2012 2:02 PM
> *Subject:* Re: [NSRCA-discussion] Going Electric - Battery Questions
>
> Larry,
>
> You have received all good advice. One thing to keep in mind, is you 
> are not going to be able to fly two full sequences with pretty much 
> any setup. With the Himax in a Monolog flying Intermediate, 20C's are 
> going to be perfect. With 20C's and good throttle management you are 
> going to be able to fly the full Intermediate and maybe four or five 
> more maneuvers. If you go up to 40C, you will find the Himax way to 
> hot for Intermediate, and you won't add that much flying time.
>
> Another thing about the Himax is it really needs an aggressive 
> throttle curve on the bottom. If you just fly it out of the box it 
> will have zip for low end and nuts for high end all at about mid 
> throttle. On the low end, you will just keep pushing and pushing and 
> nothing seems to happen until you hit mid throttle and it will go 
> nuts. The best throttle curve on my Himax looks like a snake. It ramps 
> up really fast on the low end, tappers off at mid throttle and then 
> heads back up on the high end, but you need to work it out for your 
> set up. Trust me, spending a good amount of time getting this right is 
> going to pay big dividends. If you don't, your uplines are going  to 
> be way too hot.
>
> Hey Larry,
>
> As everyone is telling you, the BIG difference between what you're 
> proposing and what you're accustomed to with Glg to below is that 
> you'll fly 90% of your sequence at half throttle.  Not figuratively 
> half throttle... but literally half, or below.  Even a vertical upline 
> does not need full motor on these setups.   Flying intermediate even 
> less so.   Also, at full throttle you'll likely only pull about 
> 75amps, so even 15C batteries would get the job done, but I would 
> stick with 20 and higher.
>
>
> Mark Atwood
> Paragon Consulting, Inc.  |  President
> 5885 Landerbrook Drive Suite 130, Cleveland Ohio, 44124
> Phone: 440.684.3101 x102  |  Fax: 440.684.3102
> mark.atwood at paragon-inc.com 
> <mailto:mark.atwood at paragon-inc.com><mailto:mark.atwood at paragon-inc.com <mailto:mark.atwood at paragon-inc.com>> 
>  | http://www.paragon-inc.com/<http://www.paragon-inc.com/>
>
>
>
>
> On Dec 7, 2012, at 1:37 PM, Larry Diamond wrote:
>
> OK, play nice... Never dealt with electrics before... I could be way 
> off base, but here is a stab at it...
>
> Is my math flawed?
>
> Motor - Himax 6330-210 F3A Motor (210KV)
> ESC - Phoenix Ice 80HV - New V2 Version
> Battery 10s - 37VDC
>
> Plane - 2M Monolog
>
> Max power range is about ~2,700 to ~3,000 watts with this set up...
>
> Calculated Battery Discharge Rate = 80Amps (ESC rating) divided by 
> 3,500mAh (battery capacity) = 22.9C
>
> Based on this math I suspect that a 30C dicharge rate is good on 
> paper... additional discharge performane = $$$ and I don't want to 
> spend money on battery performance I don't need...
>
> Class - Intermediate
>
> What is the recommended battery capacity and discharge rate...?
>
> I understand the many variables associated with the answer like, prop 
> size, temps, wind, throttle control, yada, yada, yada...
>
> I would like to fly the Intermediate sequence a couple time without 
> having to refuel electrons...
>
> Larry Diamond
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