[NSRCA-discussion] Fwd: Electric Weight Proposal LogicandRationale
Ron Van Putte
vanputte at cox.net
Thu Jun 21 15:33:52 AKDT 2007
It's not true that the "playing field" is even if both are weighed
with full fuel. As soon as the non-electric airplane started using
fuel, it would be lighter than the electric airplane and would be so
for the entire flight.
I actually like the last argument (weigh both without fuel or tank),
but it might be difficult to apply, since a lot of fuel tanks are
hard to get to.
Ron Van Putte
On Jun 21, 2007, at 6:10 PM, Fred Huber wrote:
> Again... weigh both full fuel and the "playing field" is even.
>
> Weighing empty was decided on for convenience of the CD and the
> helpers at the weigh-in.
> If you weigh with tank empty... and the weight limit is maximum
> allowed, then having fuel in can only hurt you.
> If you weigh in the planes full of fuel, then people can come up
> with ways to make the tank hold less durring weigh-in. (Strap that
> velcro around it TIGHT and reduce the tank volume for example)
> While the easier to get away with tricks would only give a marginal
> change. (maybe 1/2 to 1 oz for the velcro trick) that little bit
> could mean the difference between making weight or being disqualified.
>
> E-power planes are being weighed with each pack that is allowed to
> be used at the contest. (at the NATS) and that can lead to some
> LONG weigh-ins... Just as an inspection to ensure the glow models
> really do have a full tank when weighed. Thats just the way it is.
>
> It could be argued that the e-power plane's battery is just fuel...
> and thus shouldn't be included AT ALL in its weigh-in... Pull the
> glow plane's fuel tank.. and weigh both without fuel or tank...
> ----- Original Message -----
> From: DaveL322 at comcast.net
> To: NSRCA Mailing List
> Sent: Thursday, June 21, 2007 3:30 PM
> Subject: Re: [NSRCA-discussion] Fwd: Electric Weight Proposal
> LogicandRationale
>
> Fred,
>
> And they have quit improving glow engines?
> ********Certainly glow continues to improve, but as a well
> established medium, it is not improving at the same rate as electric.
>
> Didn't they just come out with a 2.0 ci glow engine thats light
> enough to stick on a Pattern plane?
> ********Yes.
>
> Saying we can't do something because technology wil advance means
> you must want to go back to the days when the Sig King Kobra was a
> top of the line plane. Anything with higher performance than thhat
> had using 1975 technology is not allowed.
> ********That was not my statement. My statement was that a rules
> change for an intended purpose needs be additionally evaluated for
> unintended consequences (pattern has a long history of unintended
> consequences from short sighted rules).
>
> Glow planes DO bennefit from carrying more weight... you can bolt
> on that 2.0 ci engine and carry a 30 oz fuel tank to feed it....
> and because you weigh empty you gain the bennefits of added power
> making the added fuel weight inconsequential. Glow can compensate
> for the higher fuel consumption that comes with higher power and
> not blink.
> ********Fair enough. However, the intended context/framework was
> the comparison of additional weight in the form of fuel to a glow
> plane with no other changes, and the addition of weight (in the
> form of battery) to an electric plane with no other changes. The
> intended context aside, there are also several other complicating
> factors such as wingloading, noise, structural considerations, etc.
>
> The basic conclusions I made remain unchanged.
>
> Regards,
>
> Dave
>
> ----- Original Message -----
> From: Davel322 at comcast.net
> To: NSRCA Mailing List
> Sent: Thursday, June 21, 2007 12:09 PM
> Subject: Re: [NSRCA-discussion] Fwd: Electric Weight Proposal Logic
> andRationale
>
> Not a good proposal.
>
> The fatal flaw is this - Glow planes receive no benefit from
> carrying additional weight. Adding weight to glow reduces the
> power to weight ratio, carrying un-needed fuel detracts from
> performance. Adding more battery weight to an electric could
> substantially increase the power output AND power to weight ratio.
>
> Additionally, the proposal fails to acknowledge the inherent
> benefits of electrics over glow (reduced structure is possible with
> reduced vibration, reduced finish is possible with lack of
> oil...and many more).
>
> An additional flaw (conceptually) is that this idea is very
> shortsighted. Electrics are still in their infancy. The motors,
> batteries, and ESCs will all get lighter and more efficient (and
> cheaper) with future develepment. Airframes tailored for electric
> will continue to improve further reducing weight. Within the
> existing rules structure, a very solid arguement could be made that
> electrics can already achieve equal performance to glow, and a very
> solid arguement could also be made that a cutting edge electric has
> better performance than a cutting edge glow. Electrics do not need
> any additional advantages at this time and will be dominant in the
> near future within the existing rules structure.
>
> An average flying weight for glow of 11.5 lbs assumes the average
> dry weight is 11 lbs. 11 lbs is not the average dry weight.
>
> The assumption that 20 fluid oz is the average tank size needed for
> completion of a pattern flight assumes a Masters or FAI preliminary
> flight. Not all flights are for Masters and FAI. Substantially
> less fuel is needed for Adv, Int, and Sportsman. Further, the
> assumption would also seem to be based on a glow engine with a very
> high fuel consumption ratio. Plenty of 2C setups complete Masters
> and FAI on 12 oz.....well managed 4Cs do almost as well. Perhaps
> 14 fluid oz would be a better average (~11 oz actual weight).
>
> The past few years, I've been fortunate to be flying some very high
> quality composite models (glow Vivats and electric Prestiges). The
> Vivats were 9 lbs 14 oz + 12 oz of fuel (more than enough for the
> Webra 160MC to get through 1.5 PO7s) for an average flight weight
> of 10 lbs 4 oz. My electric Prestige with TP5300s was 10 lbs even
> on the 2006 NATs scale.....current configuration puts it at 10 lbs
> 3 oz. At ~$1900 USD per copy, the Vivat and Prestige are not
> cheap, but hardly the most expensive option. On the lower end of
> the price scale, there are plenty of options from UltraRC, Fliton,
> etc, that can be well under weight electric or glow. The Black
> Magic series is among the biggest planes currently and recently
> available and can be built at 10 lbs electric and well under 10 lbs
> glow.
>
> Applicable to this proposal (and others past, current, future) is
> that the proposal should be evaluated from the perspective of a
> competitor looking for a competitive advantage - ie, not how the
> proposal will effect current equipment/desigsn, but what higher
> levels of performance could potentially be achieved by a competitor
> looking to exploit the new rules. Historically, any increase in
> size, weight, or displacement has resulted in larger and more
> expensive airframes.
>
> Regards,
>
> Dave Lockhart
> DaveL322 at comcast.net
>
>
> -------------- Original message --------------
> From: Ron Van Putte <vanputte at cox.net>
> I got the following from John Fuqua. He is going to submit a
> proposal to increase the weight limit for electric-powered
> airplanes to 11.5 lbs. I suggested to him that he "float" his
> rationale by the NSRCA Discussion List, to get some feedback. Here
> is his response.
>
> Ron Van Putte
>
> Begin forwarded message:
>
>> Date: June 21, 2007 10:40:36 AM CDT
>> To: "Ron Van Putte" <vanputte at cox.net>
>> Subject: Electric Weight Proposal Logic and Rationale
>>
>> Now that I am flying electrics I have come to realize the penalty
>> that electric planes have when being built that gas planes to not
>> have. That building penalty is significant under the current
>> rules. Electrics must be built lighter, to include paranoid
>> attention to everything used - wood, paint, fittings, etc., - all
>> to make weight. Much more of a concern than gas planes. Also I
>> remember many instances at the NATs when we were weighing
>> airplanes, when the contestant was doing all he could do to meet
>> weight with a gas plane to include cleaning the fuel residue
>> inside and out. A lot of gas planes were weighing in at 10lb 11oz,
>> 10lb 11.9 oz, even one that was only a few grams under 5 kilos.
>> Then they get to add a minimum of 16 to 20 ozs of weight by
>> fueling up (and there is no limit to fuel capacity). Takeoff
>> weights are 12 lbs or more. This situation seems bizarre and
>> illogical when you put some thought into it. Electrics have a
>> finite weight and gas! ! plane s are open ended at Takeoff. Even
>> though the 2005 NSRCA survey did not support an electric weight
>> increase it occurred to me that the survey did not offer any logic
>> or rationale as to why some increase would be justified or not. I
>> have attempted below to come up with a reasonable compromise on
>> electric weight allowance. I believe the rationale supports an
>> increase but it would be nice to have NSRCA membership look at it
>> to find the fatal flaw in the rationale before it gets submitted.
>> The two paras below are taken from the proposed change. Lets put
>> it out and see what the discussion list comes up with.
>>
>> John
>>
>> Change paragraph 4.3 Weight and Size page RCA-2 to read: No model
>> may weigh more than 5 kilograms (11 pounds) gross, but excluding
>> fuel, ready for takeoff. Electric models are weighed with
>> batteries and are allowed an additional 8 ounces for a total of
>> 11.5 pounds ready for takeoff. No model may have a wingspan or
>> total length longer than two (2) meters (78.74 inches).
>>
>>
>> Logic behind proposed change, including alleged shortcomings of
>> the present rules. State intent for future reference.
>>
>> Today’s 2 meter RC Aerobatics fuel powered aircraft typically use
>> fuel tanks with a 20 fluid ounce capacity. A 20 fluid ounce Crank
>> Tank containing 25% Cool Power Pro Pattern fuel was tested. The
>> fuel weighed 17.3 ounces. Allowing for variation in tank sizes and
>> fuel type a conservative weight of 16 ounces of fuel on average
>> seems appropriate. This means that an allowable takeoff weight for
>> fuel powered aircraft is at least 12 pounds. Assuming that all
>> fuel is consumed during the flight, the average weight for the
>> aircraft is 11.5 pounds. By restricting electric powered aircraft
>> to the takeoff weight of unfueled aircraft an unfair weight
>> penalty is being arbitrarily imposed against the electric model.
>> By allowing electric aircraft an AVERAGE flying weight of the fuel
>> powered aircraft, flying weight equity is restored.
>
>
>
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