X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from paris.boulder.noaa.gov ([140.172.10.145] verified) by logan.com (CommuniGate Pro SMTP 5.1c.2) with ESMTP id 1226603 for flyrotary@lancaironline.net; Thu, 06 Jul 2006 19:04:29 -0400 Received-SPF: none receiver=logan.com; client-ip=140.172.10.145; envelope-from=William.P.Dube@noaa.gov Received: from [140.172.241.126] (mungo.al.noaa.gov [140.172.241.126]) by email.boulder.noaa.gov (iPlanet Messaging Server 5.2 HotFix 2.01 (built Aug 26 2004)) with ESMTPSA id <0J2000HEW82A0X@email.boulder.noaa.gov> for flyrotary@lancaironline.net; Thu, 06 Jul 2006 23:03:46 +0000 (GMT) Date: Thu, 06 Jul 2006 16:58:11 -0600 From: Bill Dube Subject: Re: [FlyRotary] Re: Nothing to do with Rotary Engines, but.... In-reply-to: To: Rotary motors in aircraft Reply-to: William.P.Dube@noaa.gov Message-id: <44AD9583.1060300@noaa.gov> Organization: NOAA Aeronomy Lab MIME-version: 1.0 Content-type: multipart/alternative; boundary="Boundary_(ID_5FIg/UzYIDri69hBnPAI2w)" X-Accept-Language: en-us, en User-Agent: Mozilla Thunderbird 1.0.2 (Windows/20050317) References: This is a multi-part message in MIME format. --Boundary_(ID_5FIg/UzYIDri69hBnPAI2w) Content-type: text/plain; charset=ISO-8859-1; format=flowed Content-transfer-encoding: 7BIT Think about how small the alternators on big HP APU's are and you get the picture on how small you can make a powerful electric motor if you are willing to work at it a bit. You can easily make a 100 HP electric motor that weighs 100 lbs. It would not likely be DC, however. Electric motors for stationary use have no constraint on weight. The only reason you would want to make one lighter would be to save on materials and/or on shipping. If you make a motor of a given HP lighter, it will cost more, spin faster, or be less efficient than the heavier motor. If you are running on batteries, you must be careful not to save weight on the motor by compromising efficiency, only to add to the total vehicle weight by requiring more batteries to make up for the reduced motor efficiency. Bill Dube' george lendich wrote: >>Hi Bill, >> >>I'm relieved. I won't have to mortgage the house until the technology >>advances enough to reduces the weight by a factor of 5. Currently it >>looks like I would need about 1400 lbs of batteries. Get it down to >>280 lbs and allow 100 lbs for the electric motor and my W&B will work >>out about right. :) >> >>I'm looking forward to seeing what you come up with for the aircraft >>batteries. >> >>Bob W. >> >> > >Bob or Bill >I would have thought a 130hp DC Motor would weigh more than 100lbs. >Any rule of thumb on weight of motor to power output ?- I guess there's a >lot of copper windings per HP!? >George (down under) > > > >-- >Homepage: http://www.flyrotary.com/ >Archive and UnSub: http://mail.lancaironline.net/lists/flyrotary/ > > > --Boundary_(ID_5FIg/UzYIDri69hBnPAI2w) Content-type: text/html; charset=ISO-8859-1 Content-transfer-encoding: 7BIT Think about how small the alternators on big HP APU's are and you get the picture on how small you can make a powerful electric motor if you are willing to work at it a bit. You can easily make a 100 HP electric motor that weighs 100 lbs. It would not likely be DC, however.

Electric motors for stationary use have no constraint on weight. The only reason you would want to make one lighter would be to save on materials and/or on shipping. If you make a motor of a given HP lighter, it will cost more, spin faster, or be less efficient than the heavier motor. If you are running on batteries, you must be careful not to save weight on the motor by compromising efficiency, only to add to the total vehicle weight by requiring more batteries to make up for the reduced motor efficiency.

Bill Dube'

george lendich wrote:

Hi Bill,

I'm relieved.  I won't have to mortgage the house until the technology
advances enough to reduces the weight by a factor of 5. Currently it
looks like I would need about 1400 lbs of batteries.  Get it down to
280 lbs and allow 100 lbs for the electric motor and my W&B will work
out about right. :)

I'm looking forward to seeing what you come up with for the aircraft
batteries.

Bob W.


Bob or Bill
I would have thought a 130hp DC Motor  would weigh more than 100lbs.
Any rule of thumb on weight of motor to power output ?- I guess there's a
lot of copper windings per HP!?
George (down under)



--
Homepage:  http://www.flyrotary.com/
Archive and UnSub:   http://mail.lancaironline.net/lists/flyrotary/

--Boundary_(ID_5FIg/UzYIDri69hBnPAI2w)--