X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from mail-lpp01m010-f52.google.com ([209.85.215.52] verified) by logan.com (CommuniGate Pro SMTP 5.4.4) with ESMTPS id 5481556 for flyrotary@lancaironline.net; Sat, 14 Apr 2012 14:57:09 -0400 Received-SPF: pass receiver=logan.com; client-ip=209.85.215.52; envelope-from=fluffysheap@gmail.com Received: by lahi5 with SMTP id i5so2710987lah.25 for ; Sat, 14 Apr 2012 11:56:32 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; bh=fy5mlkmm533dyKTruu1XC98yoBVUKWs9DfunmKrLQek=; b=ceh3b8bus7TRg6JKog26W8D2IMtXX/EDoOqU1oEGjJysrFk0KNzxDbcWmbx8ul+JN9 vJTeDmJ3Ak2KqhIhpV9IVqQ3zdXAAhaUIKJ0lW5IBLMrKSLFPj6QO1WyYpGw/J6Ogxw6 dxxYy7kt8rupIdUjeeLE2SB+IETUKOIcCDk6j1Rt0PKHYddudSoSaIVvBWcpDeunm3F6 vLdgByVW/emFoBp+OmG5JfJ5L1AzzCgD70pe+YMxfRWo0nRWPx5wDYv/RlTxqs6uV6or qb2BrvJ2+X+PgGz76v8drxQOFm6Z+NiaTCQ1fhSAvwta1owAy8UkeaDBcraG3Oa0h0/v 8K6g== MIME-Version: 1.0 Received: by 10.112.17.201 with SMTP id q9mr2695232lbd.10.1334429792456; Sat, 14 Apr 2012 11:56:32 -0700 (PDT) Received: by 10.112.151.103 with HTTP; Sat, 14 Apr 2012 11:56:32 -0700 (PDT) In-Reply-To: References: Date: Sat, 14 Apr 2012 12:56:32 -0600 Message-ID: Subject: Re: [FlyRotary] Re: Laser Ignition, was: [FlyRotary] Re: The 16X is A L I V E... From: William Wilson To: Rotary motors in aircraft Content-Type: multipart/alternative; boundary=bcaec55406d8c1cf1504bda82565 --bcaec55406d8c1cf1504bda82565 Content-Type: text/plain; charset=ISO-8859-1 I believe some of the heat problems could be overcome by designing the laser to work at the engine's operating temperature, rather than at room temperature. Then you can use a Peltier cooler to just keep the laser stable at the temperature it naturally wants to be at rather than fighting the engine heat. The problem would be getting the engine, or at least the laser, properly warmed up. I wonder how long it would take for a Peltier cooler to heat a laser from 20 below up to 200 degrees? Of course, if everything's going over fiber, you don't necessarily need as much cooling, but then you have other problems. I think the squeegee action of the apex seals will help a lot with window fouling. They usually keep the rotor housing fairly clean in the areas where they make solid contact. Sort of like the cylinder walls in a piston engine, the rings keep them fairly clean even if the head looks like you could plant flowers in it. Whether it's enough, I can't say. On Sat, Apr 14, 2012 at 9:39 AM, wrote: > ** > Ran this by a girlfriend who gets to play with weapon grade energy stuff, > she blew a hole through her kitchen wall with a single pulse from a > homebrew laser in college, glad she's on our side. > My greatest concern is that in the lab under ideal conditions a laser > sounds great, under the hood in the real world is another matter, at 10k ft > a serious matter. > She plays with this stuff every day, here is her reply: > > /begin > Subj: Re: laser ignition > > Hey there, > No, that doesn't make a lot of sense. Not only is the window issue a > serious problem that I don't know how you would overcome. There is also an > issue of heat. A solid state laser has a really crappy mode so in order to > get the fluence needed to ignite the fuel, the laser would have to be in > the near-field. Diffraction losses past this point will not let the beam > focus tight enough to have enough energy to heat anything sufficiently for > ignition. With the laser being this close to the engine, heat becomes a > serious problem. As the lasers temperature changes, more than a couple of > degrees C, the wavelength shifts. A change of 2 degrees C can cause a > solid state (diode) laser to shift wavelength enough where it is no longer > at the proper resonance and the power drops significantly. Even with > active cooling on the laser, which would be required, the heat of the > engine would probably be greater than what a TC cooling device can handle. > A higher power DPSS style laser could be used and launched into fiber > which could solve the heat problem but now you have the grime and > combustion by-products in the engine that would definitely foul a fiber or > an optical window which would induce diffraction and cause a fluence drop. > So, I personally don't see how they could make this work. Or even why for > that matter. High voltage is cheap and has worked well for over 100 years. > /end > > It's her last paragraph that concerned me the most. I spent 20 years > working with HID systems focused into fiber optics. Her last sentence says > it all. > I am not against innovation but I am very cautious. > Chrissi & Randi > www.CozyGirrrl.com > CG Products, Custom Aircraft Hardware > Chairwomen, Sun-N-Fun Engine Workshop > > In a message dated 4/13/2012 11:38:05 A.M. Central Daylight Time, > echristley@att.net writes: > > CozyGirrrl@aol.com wrote: > > And all this will work only if the combustion chamber is always squeaky > > clean, no deposits or film on the windows, once that happens it all goes > > to heck quickly. > > > > If you've got a film building up on the rotor housing's chrome face, > aren't you behind the curve already? I could see > it being a problem in a piston cylinder's head. I've had to chip off gunk > with a screwdriver it had built up so thick. > But they aren't constantly being wiped by an apex seal like in a rotary. > > -- > Homepage: http://www.flyrotary.com/ > Archive and UnSub: > http://mail.lancaironline.net:81/lists/flyrotary/List.html > > --bcaec55406d8c1cf1504bda82565 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable I believe some of the heat problems could be overcome by designing the lase= r to work at the engine's operating temperature, rather than at room te= mperature.=A0 Then you can use a Peltier cooler to just keep the laser stab= le at the temperature it naturally wants to be at rather than fighting the = engine heat.=A0 The problem would be getting the engine, or at least the la= ser, properly warmed up.=A0 I wonder how long it would take for a Peltier c= ooler to heat a laser from 20 below up to 200 degrees?

Of course, if everything's going over fiber, you don't necessar= ily need as much cooling, but then you have other problems.

I think = the squeegee action of the apex seals will help a lot with window fouling.= =A0 They usually keep the rotor housing fairly clean in the areas where the= y make solid contact.=A0 Sort of like the cylinder walls in a piston engine= , the rings keep them fairly clean even if the head looks like you could pl= ant flowers in it.=A0 Whether it's enough, I can't say.

On Sat, Apr 14, 2012 at 9:39 AM, <CozyGirrrl@aol.com&g= t; wrote:
Ran this by a girlfriend who gets to play with weapon grade energy stu= ff,=20 she blew a hole through her kitchen wall with a single pulse from a homebre= w=20 laser in college, glad she's on our side.
My greatest concern is that in the lab under ideal conditions a laser= =20 sounds great, under the hood in the real world is another matter, at 10k ft= a=20 serious matter.
She plays with this stuff every day, here is her reply:
=A0
/begin
Subj: Re: laser ignition
=A0
Hey there,=20
No, that doesn't=20 make a lot of sense. =A0Not only is the window issue a serious problem that= I=20 don't know how you would overcome. =A0There is also an issue of heat. = =A0A=20 solid state laser has a really crappy mode so in order to get the fluence n= eeded=20 to ignite the fuel, the laser would have to be in the near-field.=20 =A0Diffraction losses past this point will not let the beam focus tight=20 enough to have enough energy to heat anything sufficiently for ignition.=20 =A0With the laser being this close to the engine, heat becomes a serious=20 problem. =A0As the lasers temperature changes, more than a couple of degree= s=20 C, =A0the wavelength shifts. =A0A change of 2 degrees C can cause a solid= =20 state (diode) laser to shift wavelength enough where it is no longer at the= =20 proper resonance and the power drops significantly. =A0Even with active=20 cooling on the laser, which would be required, the heat of the engine would= =20 probably be greater than what a TC cooling device can handle.
A higher power=20 DPSS style laser could be used and launched into fiber which could solve th= e=20 heat problem but now you have the grime and combustion by-products in the e= ngine=20 that would definitely foul a fiber or an optical window which would induce= =20 diffraction and cause a fluence drop. =A0So, I personally don't see how= they=20 could make this work. =A0Or even why for that matter. =A0High voltage is=20 cheap and has worked well for over 100 years.
/end
=A0
It's her last paragraph that concerned me the most. I spent 20 yea= rs=20 working with HID systems focused into fiber optics. Her last sentence says = it=20 all.
I am not against innovation but I am very cautious.
Chrissi &=20 Randi
www.CozyG= irrrl.com
CG=20 Products, Custom Aircraft Hardware
Chairwomen, Sun-N-Fun Engine Workshop=
=A0
In a message dated 4/13/2012 11:38:05 A.M. Central Daylight Time,=20 echristley@att.net<= /a> writes:
CozyGirrrl@aol.com wrote:
> And all this will work only if the=20 combustion chamber is always squeaky
> clean, no deposits or film o= n the=20 windows, once that happens it all goes
> to heck quickly.
>= =A0=20

If you've got a film building up on the rotor housing's c= hrome face,=20 aren't you behind the curve already?=A0 I could see
it being a pro= blem=20 in a piston cylinder's head.=A0 I've had to chip off gunk with a= =20 screwdriver it had built up so thick.
But they aren't constantly b= eing=20 wiped by an apex seal like in a rotary.

--
Homepage:=A0=20 http://www.flyrot= ary.com/
Archive and UnSub:=A0=A0=20 http://mail.lancaironline.net:81/lists/flyrotary/List.html<= /a>

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