> Den tirsdag den 6. august 2013 19.59.48 UTC+2 skrev Eric Jacobsen:
> > On Tue, 06 Aug 2013 12:28:13 -0500, "DougB" <60916@dsprelated> wrote:
> >
> >
> >
> > >>On 7/30/13 3:10 PM, Tim Wescott wrote:
> >
> > >>>
> >
> > >>> It's for making an electric-powered airplane sound like it has a heavy-
> >
> > >>> metal radial engine.
> >
> > >
> >
> > >Let me know if you ever figure that out. I'm sure the model airplane
> >
> > >industry would love to know as well.
> >
> > >
> >
> > >Personally I think it's a crime to put and electric motor on a scale
> >
> > >airplane. You not only want it to look real - it's got to sound real as
> >
> > >well. I don't understand how someone can spend time building a scale
> >
> > >aircraft and put an electric motor on it - you go to take off and all you
> >
> > >hear is some high-pitched whine, which makes it sound like some Walmart
> >
> > >toy.
> >
> >
> >
> > Most of the model engines don't sound particularly real, either,
> >
> > especially the 2-strokes. Hard to make anything with less than 12
> >
> > cylinders sound like a Merlin.
> >
>
> well I'd think 27 liters has a bit to do with it too ;)
> it "only" does something like 3000rpm when pushed
>
A Merlin start is very different from a radial start. A radial is almost like
a short march of single cylinder engines. A Merlin transitions
from stopped to running starting with individual puffs of exhaust smoke
and at some point you just don't hear the starter noise anymore,
like bringing a swiss watch up to speed. The few times I have seen
this happen up close was nothing short of awe inspiring
w..
Reply by Walter Banks●October 21, 20132013-10-21
Tim Wescott wrote:
> On Tue, 06 Aug 2013 12:28:13 -0500, DougB wrote:
>
> >>On 7/30/13 3:10 PM, Tim Wescott wrote:
> >>>
> >>> It's for making an electric-powered airplane sound like it has a
> >>> heavy-
> >>> metal radial engine.
> >
> > Let me know if you ever figure that out. I'm sure the model airplane
> > industry would love to know as well.
> >
> > Personally I think it's a crime to put and electric motor on a scale
> > airplane. You not only want it to look real - it's got to sound real as
> > well. I don't understand how someone can spend time building a scale
> > aircraft and put an electric motor on it - you go to take off and all
> > you hear is some high-pitched whine, which makes it sound like some
> > Walmart toy.
>
> To make it sound realistic in flight would pretty much require a
> loudspeaker on the plane. I seem to recall seeing something like that in
> Flying Models.
>
> I just want something that'll raise eyebrows in the pits when I start my
> motor.
In my dim deep student past I spent a summer in the arctic flying an
WW II era PBY Catalina. There is nothing so heart stopping as an
idling radial from the inside, clanking of free falling valve push rods,
pops and bangs of unburned fuel from the lower cylinders being
detonated in the exhaust system. (lower plugs often foul from oil leakage
past the piston) But when it counts on a takeoff run it argues with
you barking and misfiring as the the throttle is advanced, resigning
as the last of the un burned fuel in the exhaust system explodes and
it sees it your way. All of the rattles gets substituted for an co-ordinated
roar and off you go.
One pilot/mechanic friend described an idling radial engine as
tool box full of random bolts and wrenches on a shake table.
w..
On Tue, 06 Aug 2013 13:04:16 -0500, Tim Wescott
<tim@seemywebsite.really> wrote:
>On Tue, 06 Aug 2013 12:28:13 -0500, DougB wrote:
>
>>>On 7/30/13 3:10 PM, Tim Wescott wrote:
>>>>
>>>> It's for making an electric-powered airplane sound like it has a
>>>> heavy-
>>>> metal radial engine.
>>
>> Let me know if you ever figure that out. I'm sure the model airplane
>> industry would love to know as well.
>>
>> Personally I think it's a crime to put and electric motor on a scale
>> airplane. You not only want it to look real - it's got to sound real as
>> well. I don't understand how someone can spend time building a scale
>> aircraft and put an electric motor on it - you go to take off and all
>> you hear is some high-pitched whine, which makes it sound like some
>> Walmart toy.
>
>To make it sound realistic in flight would pretty much require a
>loudspeaker on the plane. I seem to recall seeing something like that in
>Flying Models.
>
>I just want something that'll raise eyebrows in the pits when I start my
>motor.
Den tirsdag den 6. august 2013 19.59.48 UTC+2 skrev Eric Jacobsen:
> On Tue, 06 Aug 2013 12:28:13 -0500, "DougB" <60916@dsprelated> wrote:
>
>
>
> >>On 7/30/13 3:10 PM, Tim Wescott wrote:
>
> >>>
>
> >>> It's for making an electric-powered airplane sound like it has a heavy-
>
> >>> metal radial engine.
>
> >
>
> >Let me know if you ever figure that out. I'm sure the model airplane
>
> >industry would love to know as well.
>
> >
>
> >Personally I think it's a crime to put and electric motor on a scale
>
> >airplane. You not only want it to look real - it's got to sound real as
>
> >well. I don't understand how someone can spend time building a scale
>
> >aircraft and put an electric motor on it - you go to take off and all you
>
> >hear is some high-pitched whine, which makes it sound like some Walmart
>
> >toy.
>
>
>
> Most of the model engines don't sound particularly real, either,
>
> especially the 2-strokes. Hard to make anything with less than 12
>
> cylinders sound like a Merlin.
>
well I'd think 27 liters has a bit to do with it too ;)
it "only" does something like 3000rpm when pushed
-Lasse
Reply by Eric Jacobsen●August 6, 20132013-08-06
On Tue, 06 Aug 2013 13:04:16 -0500, Tim Wescott
<tim@seemywebsite.really> wrote:
>On Tue, 06 Aug 2013 12:28:13 -0500, DougB wrote:
>
>>>On 7/30/13 3:10 PM, Tim Wescott wrote:
>>>>
>>>> It's for making an electric-powered airplane sound like it has a
>>>> heavy-
>>>> metal radial engine.
>>
>> Let me know if you ever figure that out. I'm sure the model airplane
>> industry would love to know as well.
>>
>> Personally I think it's a crime to put and electric motor on a scale
>> airplane. You not only want it to look real - it's got to sound real as
>> well. I don't understand how someone can spend time building a scale
>> aircraft and put an electric motor on it - you go to take off and all
>> you hear is some high-pitched whine, which makes it sound like some
>> Walmart toy.
>
>To make it sound realistic in flight would pretty much require a
>loudspeaker on the plane. I seem to recall seeing something like that in
>Flying Models.
>
>I just want something that'll raise eyebrows in the pits when I start my
>motor.
It's pretty easy to rig it up to spontaneously combust. That always
gets attention. ;)
>>On 7/30/13 3:10 PM, Tim Wescott wrote:
>>>
>>> It's for making an electric-powered airplane sound like it has a
>>> heavy-
>>> metal radial engine.
>
> Let me know if you ever figure that out. I'm sure the model airplane
> industry would love to know as well.
>
> Personally I think it's a crime to put and electric motor on a scale
> airplane. You not only want it to look real - it's got to sound real as
> well. I don't understand how someone can spend time building a scale
> aircraft and put an electric motor on it - you go to take off and all
> you hear is some high-pitched whine, which makes it sound like some
> Walmart toy.
To make it sound realistic in flight would pretty much require a
loudspeaker on the plane. I seem to recall seeing something like that in
Flying Models.
I just want something that'll raise eyebrows in the pits when I start my
motor.
--
Tim Wescott
Wescott Design Services
http://www.wescottdesign.com
Reply by Eric Jacobsen●August 6, 20132013-08-06
On Tue, 06 Aug 2013 12:28:13 -0500, "DougB" <60916@dsprelated> wrote:
>>On 7/30/13 3:10 PM, Tim Wescott wrote:
>>>
>>> It's for making an electric-powered airplane sound like it has a heavy-
>>> metal radial engine.
>
>Let me know if you ever figure that out. I'm sure the model airplane
>industry would love to know as well.
>
>Personally I think it's a crime to put and electric motor on a scale
>airplane. You not only want it to look real - it's got to sound real as
>well. I don't understand how someone can spend time building a scale
>aircraft and put an electric motor on it - you go to take off and all you
>hear is some high-pitched whine, which makes it sound like some Walmart
>toy.
Most of the model engines don't sound particularly real, either,
especially the 2-strokes. Hard to make anything with less than 12
cylinders sound like a Merlin.
Eric Jacobsen
Anchor Hill Communications
http://www.anchorhill.com
Reply by DougB●August 6, 20132013-08-06
>On 7/30/13 3:10 PM, Tim Wescott wrote:
>>
>> It's for making an electric-powered airplane sound like it has a heavy-
>> metal radial engine.
Let me know if you ever figure that out. I'm sure the model airplane
industry would love to know as well.
Personally I think it's a crime to put and electric motor on a scale
airplane. You not only want it to look real - it's got to sound real as
well. I don't understand how someone can spend time building a scale
aircraft and put an electric motor on it - you go to take off and all you
hear is some high-pitched whine, which makes it sound like some Walmart
toy.
-Doug
_____________________________
Posted through www.DSPRelated.com
Reply by Eric Jacobsen●August 2, 20132013-08-02
On Fri, 02 Aug 2013 15:36:35 -0500, Tim Wescott
<tim@seemywebsite.really> wrote:
>On Fri, 02 Aug 2013 15:52:32 -0400, Walter Banks wrote:
>
>> radams2000@gmail.com wrote:
>>
>>> Even if you ignore clatters and random components, each individual
>>
>>> cylinder does not produce the same magnitude or spectrum as any
>>
>>> other cylinder, so there are components at all multiples of the
>>
>>> single-cylinder firing rate as well as all multiples the fundamental
>>> rpm
>>
>>> rate. This has been well-studied recently because electric cars need
>>
>>> to make fake external engine noises so that innocent pedestrians
>>
>>> are not run over. So you want your Prius to sound like a Porshe.
>>
>>> Also the video game industry has gotten pretty sophisticated about
>>
>>> making engine noises. I have seen a few papers on this and they all
>>
>>> start with "periodic waveforms are not nearly good enough". There
>>
>>> was an AES some years back with an entire track devoted to audio
>>
>>> for games. You can probably dig up the preprints.
>>
>> In real life aircraft engine sounds change a lot as a function of
>> manifold pressure and RPM. In an aircraft with a radial engine the
>> clanging of unsupported push rods makes the engine sound like the
>> exhaust roar with a rattle of a metal pail of loose bolts in a
>> relatively unloaded engine..
>>
>> There are two audio filter systems in an aircraft engine intake and
>> exhaust, both are dimensionally constant but the engine speed and
>> manifold pressure changes resonate frequencies and harmonic content. In
>> the air temperature of engine components are relatively constant.
>> You might model the input and exhaust filters and simply apply a step
>> function for each cylinder excite them tied to RPM.
>
>I'm kinda hoping I can do that.
>
>But, to make my own job harder, the intake dimensions _do_ change on a
>gasoline engine as the throttle is opened -- because the throttle is
>opening, and presenting a larger orifice through which sound can travel.
The throttle opening doesn't change the dimensions of the intake
piping or manifold, though, and so doesn't drastically affect the
resonance of the system. It can block and attenuate waves from
getting out, and change the intake pressure on an n/a system, but it
doesn't have a drastic change on the resonance.
Tuners often change the length of the input piping to match the
resonance with the desired peak torque rpm. It can affect the sound
significantly, but so can other mundane things like the location and
orientation of the air box.
Throttle position doesn't affect intake dimensions, just air flow
rate.