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Message-ID: <44B4620F.5040402@bellsouth.net>
Date: Tue, 11 Jul 2006 21:44:31 -0500
From: Charlie England <ceengland@bellsouth.net>
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To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: -  EWP Power
References: <list-1232211@logan.com>
In-Reply-To: <list-1232211@logan.com>
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Bulent Aliev wrote:

>
>> In a message dated 7/10/2006 11:43:35 AM Central Standard Time,  
>> jesse@jessfarr.com writes:
>> Have any of you ewp folks looked at CSR Performance products stuff?  
>> They
>> tell me they have a high volume pump that fits into some good looking
>> anodized aluminum housings for big block car stuff that will pump  up 
>> to 70
>> gpm and is expected to last for 5500 hours or so; and, they have a  
>> remote
>> that is something like davies-craig that is also expected to last  
>> about 5500
>> hours and pumps around 35 to 37 gpm. They run in the $250 to $300  
>> range,
>> supposedly use about 5 or 6 amps; and, I would like to learn from  
>> someone
>> else's experimentation, if possible. <g>
>> jofarr, soddy tn
>>
>
> Looks like somebody is dreaming in Technicolor. I sell DC pumps on my  
> web site. The smallest 3 GPM pump is using 5-7A and the pump is 3  
> pounds. Pump that will pump 15 GPM at 12V DC is about 30 pounds and  
> huge motor. There is no free lunch. Pumping 35-37 GPM on 5-7 amps? My  
> transponder needs 7 amps.
> Buly 

Hi Buly,
No 'drink the koolaid' level of opinion from me on EWP's, but a reality 
check is in order on the transponder statement. Put an *analog* DC amp 
meter on the supply line of your transponder. I'd just about bet that it 
won't read over 2 amps even with it replying once or twice a second. The 
stated fuse requirement in the manual rarely bares any significant 
relation to actual need of a solid state device like a transponder.

The ~200 watt output from the xp is for microseconds, followed by many 
milliseconds of minimal current draw. I'll bet that your comm with 5 
watt transmitter uses more power.

On to the pump:
Ignoring pump & motor efficiency, consider the formula for 1 horsepower 
(~746 watts, or 62 amps @12 volts): 33,000 lbs lifted 1 foot in 1 
minute. 40 gallons of water is ~320 lbs. At 1 foot of 'head', that's 
0.0097 horsepower. Someone please check my math & be sure I haven't 
displaced a decimal point; it's late & I'm sleepy. Anyone know the 
approximate 'head' pressure in feet across the pump in a car engine? 
Surely we can do a sanity check on approximate hp required to pump the 
water if we know the 'head' pressure in feet.

Charlie