X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from email6.peakpeak.com ([207.189.223.49] verified) by logan.com (CommuniGate Pro SMTP 5.1c.2) with ESMTPS id 1229093 for flyrotary@lancaironline.net; Sat, 08 Jul 2006 17:52:06 -0400 Received-SPF: none receiver=logan.com; client-ip=207.189.223.49; envelope-from=billdube@killacycle.com Received: (qmail 31286 invoked by uid 513); 8 Jul 2006 21:50:46 -0000 Received: from 71.212.197.111 by email6 (envelope-from , uid 504) with qmail-scanner-1.23 ( Clear:RC:0(71.212.197.111):. Processed in 0.708068 secs); 08 Jul 2006 21:50:46 -0000 Received: from 71-212-197-111.hlrn.qwest.net (HELO tigger.killacycle.com) (external_relay_billdube@[71.212.197.111]) (envelope-sender ) by email6.peakpeak.com (qmail-ldap-1.03) with SMTP for ; 8 Jul 2006 21:50:45 -0000 Message-Id: <7.0.1.0.0.20060708105940.01e5cb00@killacycle.com> X-Mailer: QUALCOMM Windows Eudora Version 7.0.1.0 Date: Sat, 08 Jul 2006 11:25:33 -0600 To: "Rotary motors in aircraft" From: "BillDube@killacycle.com" Subject: Lbs of Li-Ion cells per gallon of gas (was: Nothing to do with Rotary Engines, but....) In-Reply-To: References: Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; format=flowed This REALLY has nothing to do with rotary engines, but... If you are trying to do back of the envelope type calculations to figure the size of the battery pack, you can figure that it takes about 90 lbs of high-energy Li-Ion batteries to replace a gallon of gasoline. This is figuring the typical efficiency of a gasoline engine and a typical electric drive package in a vehicle. If it takes 6 gallons per hr to keep you at cruise speed, it will take 6 x 90 = 540 lbs of Li-Ion batteries to run the plane at cruise for the same amount of time. Since you will be carrying 500 extra lbs, you will have to adjust the speed or duration downward a bit to account for the additional induced drag. 540 lbs of traditional laptop "road flare" type Li-Ion cells will cost about $11,000 if you shop around for the very best deal. You have to add the expense of connecting them together and also the expense of the electronic battery monitoring system (BMS) that you need to keep these cells in balance (and to help keep them from becoming road flares.) As I said earlier, this can work well for a motor glider, but not well for a cross-country airplane. It would cost about $3.50 to fill this 540 lb Li-Ion battery pack with electricity, here in Denver. That works out to about $0.60 per electric "gallon of gas". Makes a LOT of sense for a commuter car. That is for sure. That 540 lb battery pack will take a compact car 200 miles. Absolutely nothing to do with rotary aircraft engines, like I said. :-) At 09:58 AM 7/8/2006, you wrote: >I would hazard a guess that Wendell is probably alluding to the >better energy conversion efficiency of an electric motor over an >internal combustion engine. Assuming the same energy input (whether >in the from of electricity or gasoline) a typical electric motor is >around 50% efficient where as the piston engine is around 25% >efficient in converting input energy to mechanical energy. So for >the same energy input an electric motor should give better >conversion efficiency. So you might get 100 HP out of a motor for a >200HP (electrical energy) input - whereas to get 100 HP out of a >piston engine you would need 400 HP of energy input (in the form of >gasoline) - the rest being "wasted" in form of exhaust and cooling >energy (and some friction). > >However, I agree with Jarret 1 HP = 1 HP regardless. > >Ed > >Ed Anderson >Rv-6A N494BW Rotary Powered >Matthews, NC >eanderson@carolina.rr.com >http://members.cox.net/rogersda/rotary/configs.htm#N494BW >----- Original Message ----- >From: Jarrett & Heidi Johnson >To: Rotary motors in aircraft >Sent: Saturday, July 08, 2006 11:48 AM >Subject: [FlyRotary] Re: Nothing to do with Rotary Engines, but.... > >Wendel, I was always under the impression.. 1Hp was 1 Hp regardless >of how it was created.. > >The only convertion's I've heard of were.. 1Hp= 2Dp [Donkey power] >, and 1Hp=1.5Mp [Mule power] :-) > >Jarrett >----- Original Message ----- >From: Wendell Voto >To: Rotary motors in aircraft >Sent: Saturday, July 08, 2006 9:29 AM >Subject: [FlyRotary] Re: Nothing to do with Rotary Engines, but.... > >What is the equivalent hp conversion of electric to gas engines? I'm >thinking it is about 2:1 (tried to look it up quickly, couldn't find >it), so instead of 180 hp, you would only need 90 hp electric. > >Wendell > > >Subject: [FlyRotary] Re: Nothing to do with Rotary Engines, but.... > >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/ >> >> >> > > >---------- >No virus found in this incoming message. >Checked by AVG Free Edition. >Version: 7.1.394 / Virus Database: 268.9.10/383 - Release Date: 7/7/2006