[NSRCA-discussion] Long - RE: Weight

[Chad Northeast]

Dave is spot on IMO.

Also I think one important fact may have not received enough attention.  That is that the current legal voltage limit on batteries in FAI is 42V.  Increasing the weight and therefore required power of an electric model requires that you play within that rule.  To generate the necessary static 300 W/lb that most current competitive F3A models demand today but at a new weight of say even 6 kg (13.2 lbs), using an optimistic value of 35V under load you are beyond 100A setups.  

There would need to be a complete rethink of how we are flying electric since most setups sitting in airplanes would not tolerate that power level for long.  To allow electric to be competitive and work reasonably well at a higher weight will require an increase to the voltage.

No doubt additional weight would require glow motors to change as well, but they have the simple road of simply increasing displacement to deal with that.

Another point to the discussion is that I have personally only witnessed one person failing the weigh in with an electric model.  This tells me that many who have been serious about competing have made whatever effort is required to abide by the rules and that it is readily done.  If 80% were failing the test then it would beg the question that something is broken, but I think currently the rules work well enough to keep everyone competitive and not provide any large advantage or disadvantage based on power plant.  

The person who failed the weight did not weigh his own model prior to the contest, and relied on published weight values and a calculator to determine that his model would be underweight.  The published weight of his batteries were horribly understated though.

Chad

----- Original Message -----
From: Dave <DaveL322 at comcast.net>
Date: Thursday, June 4, 2009 10:17 am
Subject: [NSRCA-discussion] Long - RE:  Weight
To: 'General pattern discussion' <nsrca-discussion at lists.nsrca.org>

> Honestly, I understand (and agree) with the intention to allow 
> the "cheap
> electric", but it is no different than trying to tweak the rules 
> for the
> "cheap gas engine" and won't (my opinion, with substantial 
> history to back
> it) work- 
> - why should the rules be tweaked to essentially allow someone 
> the latest
> greatest (electric) without paying for it (either with time, or 
> $$$, or
> experience)?  The latest greatest always cost more - that 
> is the nature of
> competition.
> - I truly believe the time spent researching, designing, crafting,
> submitting, and implementing such a proposal will largely be 
> wasted because
> the process is relatively slow and can not possibly keep up with 
> the rate of
> change in electrics as technology advances.
> - Anyone who wants to try electric - go right ahead - and fly a 
> current day
> design at a slight weight disadvantage at local comps (most guys 
> don't go to
> the NATs anyway) - no one is going to ask or care about a couple 
> ounces over
> 11 lbs.  And if they do decide to go to the NATs, they can 
> suck it up and
> buy 1 expensive pack for official flights and the scale.
> 
> With the understanding of the intent to allow cheap electrics, the
> unintended consequences of any rule change needs to be carefully 
> evaluatedprior to submitting a proposal.  In this case, the 
> unintended consequence
> will be the opportunity for the TOP LEVEL electric designs to grow
> substantially in size and weight, which will drive the cost up 
> for all
> competitors (glow and electric) to compete with the new performance
> standard.  The average plane is influenced by whatever the 
> TOP LEVEL stuff
> is - that is why both electric and glow TOP LEVEL stuff has 
> always been
> right on the limit of whatever the rules are at the time, and 
> that is the
> way it will always be - again, it is the nature of competition.
> 
> The top level electrics right now weigh well under 11 
> lbs......10 lbs is
> quite possible with electric monoplanes, which is why some are 
> able to sneak
> biplanes in under 11 lbs - of course this is by shaving every 
> ounce off the
> airframe (reducing it's lifespan and making it relatively 
> fragile) and
> pushing the lipos harder (also reducing it's lifespan).  So 
> when you look at
> 8.7 lbs considering the weight of the electrics that are marginally
> overweight (with the Zippy packs and AXI), the unintended 
> consequence is the
> guys that have 7.5 lb airframes now have 1.2 lbs of additional 
> weight to add
> to make the plane bigger - and you know it will be used, and 
> probably along
> the lines of - 
> - 6-8 oz for structure
> - 3-4 oz for more motor (more power)
> - 4-5 oz for more lipo (which would still be rated the same 5300 
> mah, but be
> heavier to allow more voltage under load, thus delivering more 
> watts through
> the course of the flight - and it will be called a "High Power 
> Prolite", or
> "High Power AEON", whatever.)
> - 1-2 oz more for bigger servos and more RX battery
> 
> And 2 years after the 8.7 lb rule is introduced, there will be a 
> cheap copy
> of the "High Power Prolite" will be available and it will weigh 
> 5 oz more,
> and the desire will be to raise the 8.7 lbs to 9.2 lbs.
> 
> Allow 5.5 kg (12 lb) or 6 kg (14.3 kg) airframes, and yes, you 
> will have
> DA50 powered stuff that is competitive with current day designs, 
> but it will
> not be competitive with the YS built for 6 kg airframes for the 
> same reason
> gas is not competitive with glow now.
> 
> Allow 5.5 kg weight limit, and you instantly solve the problem 
> of all the
> guys that are a couple oz over the current 5 kg weight 
> limit.  And the new
> designs will grow, and in 1-2 years, the new designs will be 
> showing up a
> couple oz over the 5.5 kg limit.
> 
> It may be true that for the TOP LEVELs of competition that any 
> airframe is
> obsolete in 3 years......BUT.......changing the rules to allow 
> 15 lbs
> airframes will obsolete (immediately) not only the airframes, 
> but the
> powerplants and servos.....and up the horsepower requirements 
> substantiallywhich will increase the noise (only measured at the 
> NATs) and require
> substantially more cost to reduce the noise (to achieve 94/96 db 
> at the
> NATs).
> 
> All of the above is escalation no different than what we've seen 
> in the past
> -
> - "we" started with .61 cubic inch (10 CC) limit and 5 
> kg......the only
> practical limit was the displacement.
> - "we" allowed 120 4C (big mistake, short sighted, or should 
> have been
> continually adjusted as competition 4Cs developed).  
> Airframes grew and cost
> went up....some airplanes actually exceeded 2M (which was not 
> yet a limit).
> - "we" allowed unlimited engines to, in part, cover up the 
> mistake of the
> 120 4C, and, in part, to allow cheap gas engines (another big 
> mistake, again
> short sighted).  The 2M rule went into place because that 
> was essentially
> the "largest" plane in existence at the time.  The 
> airframes got bigger
> again (fuse volume), and cost went up again, and the practical 
> limit to
> airframe size became the 5 kg weight limit.
> 
> Of course we also have the noise limit - that is really a 
> separate issue -
> but - it is worth noting that larger airplanes require more 
> power, and more
> power is more noise (or more expense to keep the noise from 
> increasing).
> "Wouldn't it be nice if"........is a dangerous lead in to rule 
> changes with
> unintended consequences.  The gas engine, the heavier lipo, 
> the heavier
> motor, the heavier airframe, etc.....will all forever be less 
> competitivebecause the limits will always be pushed by the 
> airframe/powerplant that has
> the best power to weight ratio, and that will always cost more, 
> and always
> be more sensitive to weight conscious building techniques.  
> No change in the
> rules will ever allow parity for equipment that does not have 
> the best power
> to weight ratio.
> 
> Someone else made the point that they perceived the less the 
> rules change,
> the more available airframes and equipment are (2nd hand) - I 
> couldn't agree
> more.  Stop changing the rules to allow (intended or not) 
> higher performance
> airframes, and the "old" ones won't be obsolete so quickly.
> 
> Personally, after a lot of research and planning, I switched to 
> electric in
> 2006....and the expense was big.....especially because I had 
> perfectly good
> glow stuff, and maintained glow and electric for about 1 
> year.  To date,
> I've built 3 electric airframes (1 Abbra, 2 Prestige), and 
> between them I
> have run 12 different motors of different brands, weights, 
> in/out runners,
> and just about every mounting configuration you can think 
> of.  The majority
> of the motors have been < $300, and I've always used the 
> Castle 85HV (which
> I think has always been and still is the least expensive ESC 
> available for
> the job).  My planes have weighed anywhere between 9 lbs 13 
> oz and 10 lbs 14
> depending on the configuration.  If I had the time, $$$, 
> resources, etc, I'd
> design and build my own stuff right up to the limit, whatever 
> that limit
> might be.  As I do have limits (as most of us do), I'll get 
> as close to what
> I think optimum performance is, and it may or may not be pushing 
> the limits
> (for whatever reasons). 
> 
> In the past 3 years, I've spent a huge amount of time on email, phone,
> forums, in my shop, in others shops, etc....working with people 
> on how to
> assemble electric pattern stuff....and most are not using the 
> most expensive
> airframes or equipment, and all are under 11 lbs.  Bottom 
> line is that you
> can not take the largest, cheapest, and heaviest of each respective
> component and have a sub 11 lb electric OR glow plane.  Nor 
> do you need to
> have the most expensive and lightest example of each component 
> to be
> competitive.  You do need to research, plan, and make 
> educated decisions.
> No offense to anyone with an 10 lb 18 oz plane....they do 
> exist....and most
> are being happily flown, and most can make weight for the NATs 
> if the time
> is spent in advanced.
> 
> Regards,
> 
> Dave
> 
> 
> 
> 
> 
> 
> -----Original Message-----
> From: nsrca-discussion-bounces at lists.nsrca.org
> [mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of
> verne at twmi.rr.com
> Sent: Wednesday, June 03, 2009 1:53 PM
> To: General pattern discussion
> Subject: Re: [NSRCA-discussion] Weight
> 
> Derek,
> We've discussed raising the weight before and it's always been 
> voted down. I
> believe for good reason. Dave Lockhart has steadfastly argued 
> that raising
> the weight limit will inevitably increase the size of our 
> planes, obsoleting
> anything that preceded it. I agree with him. 
> 
> What I'm trying to do is make it more feasible for someone 
> wanting to try
> electric to be able to do so without having to buy the most expensive
> equipment available. For example, at a contest last weekend, a 
> friend and
> fellow pattern pilot had a set of Zippy packs that weighed 
> roughly 5.5
> ounces more than my FlightPower packs. Pretty much the same 
> difference when
> compared to Andrew's TP packs. The Zippy's as we all know, were 
> less than
> half the cost. I know for sure that my friend would have made 
> weight with my
> FP's or Andrew's TP's, but he couldn't afford that after all the other
> "electric" purchases. 
> 
> What I'm going to propose once I have it all worked out, is that 
> electricairplanes weigh LESS than glow planes and be weighed 
> without their "fuel",
> just like glow. The Rx battery will have to be in the plane, 
> just like glow.
> Yes, I realize that there are UBEC's out there but I don't know 
> of anyone
> who trusts them with the kind of current we're running. In any 
> event, my
> preliminary research indicates that roughly 8.7 pounds should be 
> just about
> right, but I want to make sure before I submit the proposal.
> 
> Verne
> 
>   
> ---- Derek Koopowitz <derekkoopowitz at gmail.com> wrote: 
> > Verne,
> > 
> > When I was at the CIAM meeting in March one of the proposals 
> which was
> > passed by the helicopter guys (F3C) was to modify the weight 
> limit for
> their
> > helicopters effective 1/1/2010.  Here is the new wording:
> > 
> > a) WEIGHT: The weight of the model aircraft (*with *fuel *or 
> *batteries)> must not exceed *6.5 *kg.
> > 
> > Unanimously approved by the Plenary Meeting. Effective 01/01/10.
> > 
> > I'm going to feel out the rest of the F3A sub-committee 
> members to see if
> > there is interest in raising the F3A weight limit to 
> 5.5kg.  What does
> > everyone think about this?
> > 
> > -Derek
> > On Wed, Jun 3, 2009 at 7:51 AM, <verne at twmi.rr.com> wrote:
> > 
> > > Bill,
> > > I've been working up an AMA rules proposal to address that 
> very issue.
> > > Unfortunately, it won't be up for vote by the contest board 
> anytimesoon. In
> > > the meantime, there's one area you didn't mention in the 
> glow to
> electric
> > > comparison and that's that an electric plane doesn't need as much
> internal
> > > reinforcement because there's virtually no vibrational 
> effects to
> contend
> > > with that you do with glow. That equates to lighter 
> airframes being
> > > acceptable as well as small, light, lipo packs to power the 
> Rx and
> servos.
> > > An 8 minute e-flight typically uses about 50 mah. The same 
> flight in
> glow is
> > > typically 200+ mah. All that aside, most electric pilots 
> will tell you
> that
> > > making weight in electric is generally a pretty expensive 
> propositionwith a
> > > limited number of 2 meter planes available that are usually
> vacuum-bagged
> > > composite affairs. In addition, your best chances for making 
> weight will
> > > also necessitate the lightest and generally most expensive 
> motors and
> > > batteries. There are exceptio
> > >  ns, and I'm sure we're about to hear about most of 
> them, but I'll be
> able
> > > to point to just as many examples of guys that fly 
> overweight at local
> > > contests where they know they won't be weighed and the only thing
> they're
> > > really guilty of is not spending the extra money that the lightest
> batteries
> > > and motors cost. In every other way, the planes they're 
> flying are the
> same
> > > as the ones they're competing against. The proposal I'm 
> working on is
> not
> > > self-serving because my planes make weight, but getting 
> there is both
> too
> > > expensive and unreasonable, in my opinion. My proposal won't 
> be to allow
> > > electric planes to weigh more, it'll require that they weigh 
> less, but
> > > without the "fuel". The proposal will take into account that 
> electricmotors
> > > are inherently lighter than their glow counterparts as well 
> as the
> reduced
> > > structural requirements. It will limit the mah of 
> permissible packs to
> > > control that end of the equation and there's already a 
> voltage limit on
> the
> > > books which is fine as it
> > >  stands. I'm currently doing survey work at the 
> contests I go to to see
> > > where everybody is at weight-wise and will post my proposal 
> on this list
> > > soon. After that, it's up to all concerned to voice their 
> opinions to
> their
> > > respective Contest Board reps.
> > >
> > > Verne Koester
> > > AMA District 7
> > > Contest Board
> > >  ---- Bill's Email <wemodels at cox.net> wrote:
> > > >  I am certain this has been beaten to death while I 
> was off doing
> other
> > > > things, but can anyone explain this:
> > > >
> > > >
> > > > Rule 4.3: Weight and Size. No model may weigh more than 
> five (5)
> > > > kilograms (11 pounds) gross, but excluding fuel, ready for 
> takeoff.> > > Electric models are weighed with batteries.
> > > >
> > > > Why can't an electric "deduct" the equivalent of 16 ounces 
> of fuel??
> Is
> > > > a plane without fuel rally "ready for takeoff"??
> > > >
> > > > I know it is likely a direct copy of the FAI rule, but it 
> makes no
> > > > logical sense. IC powered planes are weighed without fuel 
> and can
> weigh
> > > > right at 11 pounds. Add fuel and it could add another 10 
> to 12 ounces
> of
> > > > weight. That's OK. But if an electric with batteries weight
> > > > 11.0000000000000001 pounds it is overweight by the rules.
> > > >
> > > > Put another way, what does a YS and full fuel weigh 
> compared to a
> > > > motor+ESC+batteries?
> > > >
> > > > Hacker C50 14XL = 18.2 ounces
> > > > Hacker Spin 99 ESC = 3.7 ounces
> > > > 10S packs = +/- 43 to 46 ounces
> > > >
> > > > Weight w/o batteries = 21.9
> > > > AUW w/batteries = 66.9 ounces
> > > >
> > > > YS 1.70 = 33.6 ounces (955 grams)
> > > > AUW with tank and fuel = 45 ounces +/-
> > > >
> > > >  So I can see an argument that the electrics have a 
> weight advantage
> > > > when it comes to just the motor and ESC. But with "fuel" 
> electric is
> at
> > > > a 20 ounce disadvantage.
> > > >
> > > > So if I build a plane for electric I need to build it 20 
> plus ounces
> > > > lighter than if I was going to put a nitro motor in it. 
> How does that
> > > > make sense. I know I am missing something important here, 
> so educate
> me.
> > > >
> > > >
> > > >
> > > > _______________________________________________
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