REFLECTOR: Reflector Digest, Vol 109, Issue 3

Luciano, Luis I CIV PEOSUB, PMS404P luis.i.luciano at navy.mil
Fri Apr 4 09:49:10 CDT 2014


Gerhardt - Sounds like a "cool" project :)  You always find new ways to expand the knowledge and innovation of this hobby.  I look forward to seeing your test results.

Luis
Velocity XL-5 "Dulcinea"
Build Status: Building additional funding :(

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Today's Topics:

   1. Re:  Water injection (Geoff Gerhardt)
   2. Re:  Water injection (Geoff Gerhardt)


----------------------------------------------------------------------

Message: 1
Date: Fri, 4 Apr 2014 09:52:30 -0400
From: Geoff Gerhardt <geoff.gerhardt at gmail.com>
To: "Richard J. Gentil" <richard at naples-air-center.com>
Cc: Velocity Aircraft Owners and Builders list <reflector at tvbf.org>
Subject: Re: REFLECTOR: Water injection
Message-ID:
	<CAHd2h4Lb3XuNy9HVL7L6kUPiBof7ncO3BPp687FFpBgtzsuQRw at mail.gmail.com>
Content-Type: text/plain; charset="iso-8859-1"

Richard,

I run LOP for every phase of flight except take off and climb.  I have a Dynon Skyview panel that gives me all the engine data, plus I've installed an air-fuel monitoring system that tells me the exact air/fuel ratio I'm running at.  Rather than using EGT to find LOP, I just pull back the mixture and watch the AFR - very slick.

Running LOP in cruise significantly lowers CHT's, but in climb, it doesn't lower temps.  I'll easily go over 400F if I use LOP on climb.  I think the climb attitude/speed does not produce enough cooling air flow in my configuration.  That cooling that comes from evaporating excess fuel seems to be very effective.  I think I will be able to get that same cooling with water injection, but with much less water flow.  Back of the envelope calculations - on full-rich climb, I'm burning ~12-13gal/hr where as in LOP I'd be burning ~8-9gal/hr.  So, I'm using ~4gal/hr for cooling.  Water should provide better cooling than fuel, so I'm guessing that I'll be able to get away with half that flow, say 2gal/hr water to provide equivalent cylinder cooling.  So, a 15min climb would require less than a gallon of water, so a 5gal tank would last for several flights (could probably get away with a 2gal tank).

Geoff


On Thu, Apr 3, 2014 at 11:59 PM, Richard J. Gentil < richard at naples-air-center.com> wrote:

> Hi Geoff,
>
> You can achieve better cooling by climbing using lean of peak mixture 
> setting if you have an engine analyzer especially with a turbo charged 
> engine. If you are still a little too warm you can pull back the prop 
> a little. The less explosions per minute, the cooler the engine will run.
>
> Richard
>
> Sent from my iPhone 5 Classic
>
> > On Apr 3, 2014, at 10:41 PM, Geoff Gerhardt 
> > <geoff.gerhardt at gmail.com>
> wrote:
> >
> > Guys,
> >
> > I've been considering using water injection to keep cylinder temps 
> > down
> on climb.  Seems like a better idea than running full rich all the way up.
>  It looks pretty straightforward, but I'm wondering if there's a 
> reason why others don't use it more.  For those who are not familiar 
> with water injection, essentially, you spray water (or a 
> water/methanol mix) into the intake (typically before the fuel servo).  
> The large heat of vaporization of water pulls a lot of heat out.  
> Plus, you get a bit of a performance boost both by lowering the inlet 
> charge temperature as well as the steam expansion during the power 
> stroke.  Another nice benefit is that your pistons get a nice steam cleaning with every stroke.
> >
> >
> > I figure a 5gal tank would do more than enough for a few trips if 
> > only
> used on climb.  I have had some high temps when cruising at high 
> altitudes as well, which it might help with.
> >
> > I'd welcome any
> > _______________________________________________
> > To change your email address, visit
> http://www.tvbf.org/mailman/listinfo/reflector
> >
> > Visit the gallery!  www.tvbf.org/gallery user:pw = 
> > tvbf:jamaicangoose Check new archives: www.tvbf.org/pipermail Check 
> > old archives: http://www.tvbf.org/archives/velocity/maillist.html
>
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Message: 2
Date: Fri, 4 Apr 2014 10:03:05 -0400
From: Geoff Gerhardt <geoff.gerhardt at gmail.com>
To: Velocity Aircraft Owners and Builders list <reflector at tvbf.org>
Subject: Re: REFLECTOR: Water injection
Message-ID:
	<CAHd2h4L7DwBFiQ6AgHeK=Dd8tOf1am9Ev6R17yBupOPxvJVv-A at mail.gmail.com>
Content-Type: text/plain; charset="iso-8859-1"

Guys,

Attached is a NACA report on water injection.  It was used in WWII by the air force to provide short bursts of increased power for use in dog fights, short take offs and the like.  Old, but it contains lots of good, fundamental info where they talk about optimal water/fuel ratios for increased power, best fuel economy (through use of advanced timing).

I am going to order a water injection kit meant for automotive use.  Drag racers use water injection quite a lot.  It has a controller that has a MAP input and it will vary the injection flow based on MAP.  I'll do some experimenting and let you know how it works.

Again, I'm new to this - anyone with experience or knowledge in water injection, please weigh in.

Thanks.

Geoff



On Fri, Apr 4, 2014 at 9:52 AM, Geoff Gerhardt <geoff.gerhardt at gmail.com>wrote:

> Richard,
>
> I run LOP for every phase of flight except take off and climb.  I have 
> a Dynon Skyview panel that gives me all the engine data, plus I've 
> installed an air-fuel monitoring system that tells me the exact 
> air/fuel ratio I'm running at.  Rather than using EGT to find LOP, I 
> just pull back the mixture and watch the AFR - very slick.
>
> Running LOP in cruise significantly lowers CHT's, but in climb, it 
> doesn't lower temps.  I'll easily go over 400F if I use LOP on climb.  
> I think the climb attitude/speed does not produce enough cooling air 
> flow in my configuration.  That cooling that comes from evaporating 
> excess fuel seems to be very effective.  I think I will be able to get 
> that same cooling with water injection, but with much less water flow.  
> Back of the envelope calculations - on full-rich climb, I'm burning 
> ~12-13gal/hr where as in LOP I'd be burning ~8-9gal/hr.  So, I'm using 
> ~4gal/hr for cooling.  Water should provide better cooling than fuel, 
> so I'm guessing that I'll be able to get away with half that flow, say 
> 2gal/hr water to provide equivalent cylinder cooling.  So, a 15min 
> climb would require less than a gallon of water, so a 5gal tank would 
> last for several flights (could probably get away with a 2gal tank).
>
> Geoff
>
>
> On Thu, Apr 3, 2014 at 11:59 PM, Richard J. Gentil < 
> richard at naples-air-center.com> wrote:
>
>> Hi Geoff,
>>
>> You can achieve better cooling by climbing using lean of peak mixture 
>> setting if you have an engine analyzer especially with a turbo 
>> charged engine. If you are still a little too warm you can pull back 
>> the prop a little. The less explosions per minute, the cooler the engine will run.
>>
>> Richard
>>
>> Sent from my iPhone 5 Classic
>>
>> > On Apr 3, 2014, at 10:41 PM, Geoff Gerhardt 
>> > <geoff.gerhardt at gmail.com>
>> wrote:
>> >
>> > Guys,
>> >
>> > I've been considering using water injection to keep cylinder temps 
>> > down
>> on climb.  Seems like a better idea than running full rich all the way up.
>>  It looks pretty straightforward, but I'm wondering if there's a 
>> reason why others don't use it more.  For those who are not familiar 
>> with water injection, essentially, you spray water (or a 
>> water/methanol mix) into the intake (typically before the fuel 
>> servo).  The large heat of vaporization of water pulls a lot of heat 
>> out.  Plus, you get a bit of a performance boost both by lowering the 
>> inlet charge temperature as well as the steam expansion during the 
>> power stroke.  Another nice benefit is that your pistons get a nice steam cleaning with every stroke.
>> >
>> >
>> > I figure a 5gal tank would do more than enough for a few trips if 
>> > only
>> used on climb.  I have had some high temps when cruising at high 
>> altitudes as well, which it might help with.
>> >
>> > I'd welcome any
>> > _______________________________________________
>> > To change your email address, visit
>> http://www.tvbf.org/mailman/listinfo/reflector
>> >
>> > Visit the gallery!  www.tvbf.org/gallery user:pw = 
>> > tvbf:jamaicangoose Check new archives: www.tvbf.org/pipermail Check 
>> > old archives: http://www.tvbf.org/archives/velocity/maillist.html
>>
>
>
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