[NSRCA-discussion] Max volts
Earl Haury
ejhaury at comcast.net
Thu Mar 4 04:02:18 AKST 2010
IC powered models improve in thrust to weight ratio as fuel is burned off, the converse is true of E powered models - power declines as battery charge (fuel) is used.
Dave's ESC requirements are exactly what is desirable. "Giving up" some early flight "punch" to ensure constant performance throughout. A lot different than having an ESC do some magic to extract more performance at the latter stages of flight. In other words, the prop rpm would be proportional to the (pilot controlled) stick position throughout a flight. Simply a more direct relation between control input and result, not unlike an IC system. The system now used is kinda "back-door" in that TX inputs are turned into a power output from the ESC that varies with input voltage resulting in different motor outputs for the same stick position.
For the sake of argument, I suppose that if one wants' to read things unintended into the rules ad nauseum, then jettisoning fuel via the exhaust is reason for not scoring a flight from the point where exhaust is seen leaving the model. From the rules: "If any part of the model aircraft is jettisoned during the flight, scoring will cease at that point and the competitor must be instructed by the flight line director to immediately land his model aircraft."
Earl
----- Original Message -----
From: Dave
To: 'General pattern discussion'
Sent: Wednesday, March 03, 2010 11:48 PM
Subject: Re: [NSRCA-discussion] Max volts
The OS EFI looked at throttle position (taken from the throttle servo signal pulse width), RPM, and temperature. I disconnected the temp sensor and found it made ZERO difference in running characteristics under normal conditions. Others reported the engine would not even start without the temp sensor connected. My understanding is that EFI computer unit basically compared throttle position to RPM and adjusted the mixture to reduce rich/lean spots as the engine came on/off the pipe.
The "biggest lie" about electrics is that they always produce the same amount of power. Phooey. Ambient temperature has a big influence.
So far as the ESC feature I would like to have...it is not a governor like the governor mode from the heli software or the governor mode Dean has worked with for CL Stunt. And I certainly don't want my electric setup to emulate an IC (if I did, I'd just fly IC). What the feature is, is a way to "clip" peak power at the beginning of the discharge cycle to maintain a constant peak power (if/when requested by advancing the throttle stick to 100%) and constant part throttle power. In the instance of a fresh battery being capable of 6500 RPM, it might be limited to 6100 RPM...and ½ throttle would be 4500 RPM (for instance). As the battery is discharged, it might only be capable of 6200 RPM, but full throttle would remain 6100 RPM, and ½ throttle would remain 4500 RPM. Think of it more as the way modern TX output strength is controlled....whether the TX battery is freshly charged at 11 volts (Nixx) or near depleted at 9.3 volts.the signal output strength is the same.
So far as a 45 upline or vertical upline..certainly electric or IC both need throttle adjustments to maintain constant airspeed. A "governor" that maintains constant prop RPM could be applied to either setup (and potentially maintain constant airspeed without an input from the pilot). In practice, less throttle adjustment is needed with an electric, because as the load on the electric increases (airspeed decreases when climbing), the electric motor attempts to maintain the RPM from the start of the climb (KV*volts) by drawing more amps to maintain the RPM. IC doesn't do this..more load on engine results in a loss of RPM (absent any specific tuning effects of the exhaust system, mixture, etc).
I think the intent of the rules are clear enough, and need to be updated to reflect the current technology.
Regards,
Dave
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From: nsrca-discussion-bounces at lists.nsrca.org [mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of rcmaster199 at aol.com
Sent: Wednesday, March 03, 2010 11:48 PM
To: nsrca-discussion at lists.nsrca.org
Subject: Re: [NSRCA-discussion] Max volts
Ed,
I'm not so sure. Most IC's don't have a pressure regulator...the YS is about the only one. This a passive device that has fixed settings. Dave's example of the EFI may be a dfferent story though...I never spent any time dealing with the OS EFI so I don't know how it worked.
The problem with such analogies is that gas and glow fuels have a fixed amount of pop per unit mass. Put in X amount and you will pretty much get Y out for any given set-up, even poor ones. Y would vary of course depending on how good the set-up was, meaning different operators will probably get different Y's. However Y would be pretty much fixed for each operator
Batteries on the other hand, have a continuously variable amount of pop per unit mass. Electronically taking the variable input volts and, through some apparently straight forward software, drive a constant Y at the motor, is where I am having some issue with.
As for ESC's not doing much to alter the piloting of the model, again I am not so sure. Dean used a good example: at near the end of the flight, let's assume there is a diagonal or vertical. The battery has lost some pop and the motor won't be able to keep up under constant throttle conditions. The pilot would need to make a throttle adjustment to maintain momentum. If the ESC had this new programming, the pilot would fly through this without hardly noticing or changing his flying, just like we do with ICs. I certainly am NOT opposed to reducing pilot work load...it's the how not the what.
And in this particular instance, equality between the types of propulsion IS what the programmable ESC proponents want.....
The rule as written is sticky. I think that some type of clarification or addendum to the rule, as Earl suggested, would eliminate the sticky wicket if you will.
BTW- I am not implying that Dean is against the programmable ESC, far from it. He has thought through what would be needed to accomplish the task. In fact, he did something similar to Bob Hunt's WC stunt entry a few years ago.
Matt
-----Original Message-----
From: Ed Alt <ed_alt at hotmail.com>
To: NSRCA List <nsrca-discussion at lists.nsrca.org>
Sent: Wed, Mar 3, 2010 7:56 pm
Subject: Re: [NSRCA-discussion] Max volts
I actually was only halfway joking I said "Ban the YS Pressure Regulator", or something like that. Not that I really think it should be banned, but for everyone who thinks it would be cheating to have an ESC that can auto-compensate for dwindling battery voltage, then you ought to seriously think about why it is OK to have a automatic pressure regulator in a recip. There isn't much difference, other than one is wet and the other is dry. And the other key point about having an ESC with this feature is that it doesn't do anything to alter the piloting of the model based on the external conditions that the model is encountering. All it is doing is de-rating the output of the the battery to make it consistent throughout its useful operation range.
Ed
------------------------------------------------------------------------------
To: nsrca-discussion at lists.nsrca.org
Date: Wed, 3 Mar 2010 13:58:30 -0500
From: rcmaster199 at aol.com
Subject: Re: [NSRCA-discussion] Max volts
Dave,
I would argue that the ESC has the sensor built. It isn't a sensor in the sense of a mag pick up such as CDI devices have. It is rather an exact frequency determination to which the motor is driven. It is simpler and hidden. Should we go back on mechanical advance....God no./
I think the CDI electronic advance is similar to today's digital servo. The former advances spark pulsing based on rpm and the latter advances motor output torque based on input load. Whether each violates, not sure. Needs more thought and comparison to the rules. My first take would be to say NO because the magnitude of adjustment is fixed
Matt
----- Original Message -----
From: Dave
To: 'General pattern discussion'
Sent: Wednesday, March 03, 2010 9:47 AM
Subject: Re: [NSRCA-discussion] Max volts
Matt,
One more thought/consideration/question -
Is electronic ignition with variable timing advance illegal? Essentially the RPM is sensed (through a sensor), and as RPM increases, the timing is advanced. The ESCs of today do the same function.they advance timing as RPM increases, but do so without sensor. Should we go back to sensors and mechanical advance devices?
Regards,
Dave
On Mar 2, 2010, at 8:15 AM, rcmaster199 at aol.com wrote:
I had a brief conversation with Dean Pappas on this subject recently. Dean explained that some folks have been advocates of programming the ESC to do some footwork at various stages of battery use. He explained to me just how easy this is to do physically. It seems a few have mentioned something similar in this thread.
I am not that concerned about raising the voltage of the battery as I see this as a somewhat clear violation of the FAI code. I am more concerned about what and how the ESC is "programmed" . I would like for some one with the electronic/software pedigree to explain to me how programming adjustable rates of voltage potential and making these adjustments automatically, does not constitute a programming violation within the rules as they exist today.
When the rules were written, we were clearly dealing with RADIO pre-programmed sequences and the like, no gyros, etc. However I would argue that rate auto adjustments that are definitely possible with the ESC's of today, also qualify as a violation of said rules. Someone should sit down and think this through...I could be convinced otherwise but it needs to be a good argument
MattK
-----Original Message-----
From: Anthony Romano <anthonyr105 at hotmail.com>
To: nsrca-discussion at lists.nsrca.org
Sent: Tue, Mar 2, 2010 8:29 am
Subject: Re: [NSRCA-discussion] Max volts
Keep this line of thinking in mind next time we talk about weight limits! Or any other rules proposal.
Anthony
> From: burtona at atmc.net
> To: nsrca-discussion at lists.nsrca.org
> Date: Mon, 1 Mar 2010 22:45:57 -0500
> Subject: Re: [NSRCA-discussion] Max volts
>
> OK, So I have a question. Is knowingly and purposefully violating the intent
> and letter of the rules to gain a performance advantage called cheating?
> ....... Just asking!
> Dave Burton
>
> -----Original Message-----
> From: nsrca-discussion-bounces at lists.nsrca.org
> [mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of James Oddino
> Sent: Monday, March 01, 2010 7:16 PM
> To: General pattern discussion
> Subject: Re: [NSRCA-discussion] Max volts
>
> I have the functional concept that solves the rules problem. Picture a 10S
> pack positive lead wired to the common of a switch with two poles, a piece
> of wire connected from one pole to a pole on a second two pole switch with
> its common connected to the ESC. Between the other two poles we place our
> 11th cell. When the 10S pack is above 37.5 volts the 11th cell is bypassed
> and when it is below, like it will be during vertical maneuvers late in
> flight, the 11th cell is put in series to boost the voltage to up to 41.7
> volts. At no time is the voltage over the spec.
>
> Having said that, I believe the 10S system provides adequate power with the
> right motor at all times of flight even if the voltage drops to 35 volts.
>
> Jim
>
>
> On Mar 1, 2010, at 8:59 AM, Bob Kane wrote:
>
> > Going higher and regulating down would be against the rules, the max volts
> is still limited to 42.56.
> >
> > Bob Kane
> > getterflash at yahoo.com
> >
> >
> > --- On Mon, 3/1/10, krishlan fitzsimmons <homeremodeling2003 at yahoo.com>
> wrote:
> >
> >> From: krishlan fitzsimmons <homeremodeling2003 at yahoo.com>
> >> Subject: Re: [NSRCA-discussion] Max volts
> >> To: chad at f3acanada.org, "General pattern discussion"
> <nsrca-discussion at lists.nsrca.org>
> >> Date: Monday, March 1, 2010, 9:54 AM
> >>
> >> Couldn't we go to a higher voltage and
> >> regulate it back down? A contstant 42.56v would be nice!
> >>
> >> Chris
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >> From: Chad
> >> Northeast <chad at f3acanada.org>
> >> To:
> >> nsrca-discussion at lists.nsrca.org
> >> Sent: Sun,
> >> February 28, 2010 8:48:48 PM
> >> Subject: Re:
> >> [NSRCA-discussion] Max volts
> >>
> >> You would be at about 50% capacity at 3.85 ish volts/cell
> >> (resting open circuit), so unless you up the capacity you
> >> will have a pretty restricted flight time.
> >>
> >> Chad
> >>
> >> On 10-02-28 9:25 PM, Ron Van Putte wrote:
> >>> That stirs a wild thought in my brain. Fully
> >> charged packs don't stay at 4.2 volts per cell very
> >> long. On the other hand, once the initial charge
> >> voltage is burned off by a constant load, the voltage loss
> >> curve "flattens out". What if you put fully
> >> charged 6S and a 5S packs in series and "burn them
> >> down" to 3.869 volts per cell (a total of 42.56
> >> volts for an 11-cell pack) so they were legal for
> >> use. Would the voltage of this depleted 11S pack be
> >> higher than a fully charged 10S pack at the end of a typical
> >> flight? If the end-of-flight voltage might be
> >> significantly higher for the 11S pack vice a 10S pack, it
> >> would be worth investigating, even considering the extra
> >> weight of the additional cell. Come on you electronic
> >> gurus, show me where I'm wrong.
> >>>
> >>> Ron Van Putte
> >>>
> >>> On Feb 28, 2010, at 10:00 PM, James Oddino wrote:
> >>>
> >>>> What comes after ...? Does it specify a load
> >> or any other conditions? Is it measured during the
> >> noise test and have a minimum value?
> >>>>
> >>>> Just stirring the pot, Jim O
> >>>>
> >>>>
> >>>> On Feb 28, 2010, at 5:21 PM, John Fuqua wrote:
> >>>>
> >>>>> No its not (assuming we are talking RC
> >> Aerobatics). Try page RCA-2 para 4.1
> >>>>> which
> >> states "Electrically-powered model aircraft are
> >> limited to a maximum
> >>>>> of 42.56 volts.."
> >>>>>
> >>>>> -----Original Message-----
> >>>>> From: nsrca-discussion-bounces at lists.nsrca.org
> >>>>> [mailto:nsrca-discussion-bounces at lists.nsrca.org]
> >> On Behalf Of Ron Van Putte
> >>>>> Sent: Sunday, February 28, 2010 7:07 PM
> >>>>> To: General pattern discussion
> >>>>> Subject: Re: [NSRCA-discussion] Max volts
> >>>>>
> >>>>> It's in the general rules, not in the R/C
> >> section.
> >>>>>
> >>>>>
> >>>>> On Feb 28, 2010, at 6:50 PM, Jim Quinn wrote:
> >>>>>
> >>>>>> Where can I find the rule
> >> for max volts?
> >>>>>>
> >>>>>>
> >> _______________________________________________
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> >>>>>> NSRCA-discussion at lists.nsrca.org
> >>>>>>
> >> http://lists.nsrca.org/mailman/listinfo/nsrca-discussion
> >>>>>
> >>>>>
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