---------------------------------------------------------- Zenith-List Digest Archive --- Total Messages Posted Sun 01/11/04: 9 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 06:25 AM - 28 volts vs 14 volts and electronics (Bill Howerton) 2. 06:39 AM - Re: 28 volts vs 14 volts and electronics (Rico Voss) 3. 06:40 AM - Re: 28 volts vs 14 volts and electronics (Benford2@aol.com) 4. 06:53 AM - Re: 28 volts vs 14 volts and electronics (Ron DeWees) 5. 08:28 AM - Re: Fuel Management update (Chesterman Family) 6. 09:07 AM - Re: Zenith-List Digest: 10 Msgs - 01/09/04 (W.R. \) 7. 01:23 PM - Re: 28 volts vs 14 volts and electronics (Ray Montagne) 8. 02:59 PM - Re: Fuel Management update (bryanmmartin@comcast.net) 9. 07:34 PM - Re: Fuel Management update (Chesterman Family) ________________________________ Message 1 _____________________________________ Time: 06:25:10 AM PST US From: "Bill Howerton" Subject: Zenith-List: 28 volts vs 14 volts and electronics --> Zenith-List message posted by: "Bill Howerton" I'm at the point where I need to start making some decisions regarding avionics, instruments and power. The questions I ask are these: 1. Are there inherent advantages and disadvantages of one over the other 2. Can electronic devices meant for one voltage system be installed on an aircraft of another with some type of converter? 3. Is there a good place to learn about these issues? ZAC produces a good set of plans for building an airplane, and the engine manufacturers produce good documentation on their engines, but what about power? Please bear in mind, my knowledge of electronics doesn't extend far beyond battery installation in my kids' toys (I think I've got this '+' an '-' thing down) but beyond that I'm lost. So I'd appreciate it if after your guffaws of laughter at my stupid questions, you answered them using very simple terminology - the fewer syllables the better Thanks! Bill Howerton - N714BH N601XL Corvair ________________________________ Message 2 _____________________________________ Time: 06:39:05 AM PST US From: Rico Voss Subject: Re: Zenith-List: 28 volts vs 14 volts and electronics --> Zenith-List message posted by: Rico Voss Bill, I suggest you tap into the Matronics "Aeroeletric-list ". It's moderated by Bob Nuckolls, who has some 30-40 years in the industry. He has written a book (about $35) that discusses the issues you have brought up, and contains several sample wiring diagrams of elegant but simple elec systems for different applications. Focus is always on reliability. Book is available on his web site, www.aeroelectric.com, along with much valuable information and some supplies. For #2, some devices can tolerate 14 or 28 volts, some would require a "converter". You'll have to check the device.. --Rico --- Bill Howerton wrote: > --> Zenith-List message posted by: "Bill Howerton" > > > I'm at the point where I need to start making some > decisions regarding avionics, instruments and power. > The questions I ask are these: > 1. Are there inherent advantages and disadvantages > of one over the other > 2. Can electronic devices meant for one voltage > system be installed on an aircraft of another with > some type of converter? > 3. Is there a good place to learn about these > issues? __________________________________ http://hotjobs.sweepstakes.yahoo.com/signingbonus ________________________________ Message 3 _____________________________________ Time: 06:40:02 AM PST US From: Benford2@aol.com Subject: Re: Zenith-List: 28 volts vs 14 volts and electronics --> Zenith-List message posted by: Benford2@aol.com In a message dated 1/11/2004 7:25:55 AM Mountain Standard Time, Bill@Howerton.com writes: > > Please bear in mind, my knowledge of electronics doesn't extend far beyond > battery installation in my kids' toys (I think I've got this '+' an '-' thing > down) but beyond that I'm lost. So I'd appreciate it if after your guffaws > of laughter at my stupid questions, you answered them using very simple > terminology - the fewer syllables the better > > Thanks! > > Bill Howerton - N714BH > N601XL Corvair > Get on the areo electric list. Bob Knuckles is the best !!!!! Ben Haas N801BH. do not archive ________________________________ Message 4 _____________________________________ Time: 06:53:11 AM PST US From: "Ron DeWees" Subject: Re: Zenith-List: 28 volts vs 14 volts and electronics --> Zenith-List message posted by: "Ron DeWees" HI Bill, I will hit a few rough spots in the discussion and let the gurus fill in the gaps. One big difference probobly isn't a factor for our small motors like the Zen aircraft use. 28 volt systems can send larger currents further on smaller wires than 12 volt systems. If I had a big V8 in front and needed a battery in the tail for balance I would opt for 28 volts as the cables could be considerably smaller and therefore lighter. Twice the voltage converts to half the current for the same power. OTOH, if I had a small 4 or 6 cyl engine and could mount the battery closeby I wouldn't consider 28 volt systems. As far as avionics I wouldn't consider mixing one voltage and another. Keep with the same voltage as the battery. You CAN convert 12 volts to 28 with a solid state inverter but they aren't more than 80 percent efficient and will consume extra power. If you use 12 volt avionics with a 28 volt system you will need some sort of resistive or electronic voltage reduction. This produces heat and, again, wastes power. In general my observation is that larger planes use 28 volt systems and smaller ones use 12. Used prices seem a bit lower for some 28 volt avionics because the market is a bit smaller. If all these decisions are yet to be made I would plan on 12 volt system unless you have serious reason to go 28 volt. 12 volt batteries are plentiful and battery chargers are cheap. Just my opinion ROn DeWees ----- Original Message ----- From: "Bill Howerton" Subject: Zenith-List: 28 volts vs 14 volts and electronics ________________________________ Message 5 _____________________________________ Time: 08:28:39 AM PST US From: Chesterman Family Subject: Re: Zenith-List: Fuel Management update --> Zenith-List message posted by: Chesterman Family keep the simple system simple guys > The designed system works great but any seemingly small change can screw up the > design. > I have the header (large) and small wing tanks on my 701 with a 582. since it is > a 1996 vintage my header tank has a vented gas cap so extra venting of the header > tank was unneccessary. With the new windshield you cannot have the fuel cap and venting is a must but what makes you think that the vent has to go up into the wing? Run it down onto the floor and out under the seat just infront of the landing gear. you are supposed to have a drain there anyway. Now for gravity feed from the wings. If you run fuel lines down the cabin tubes , gravity will do its thing but that makes for an ugly system that you must look at while flying so most run them down behind the seat as per the plans and back up to the tank. This is where gravity won't work on its own since a small amount of fuel will lay in the bottom of the fuel line under the seat. When you refill the wing tank the fuel does not have a high enough "weight" to push the fuel in bottom of the line back up to the header tank so no fuel transfer so there has to be a way to get the air out of the line from the wing tank to the floor. Put the drain control for lowest point of the system in the seat kickplate so it can be operated while in flight. On the ground it can be used to drain possible water or the wing tanks or bleed the lines on the ground and inflight when switching wing tanks as draining the first tank will result in another air lock. The next critical thing is the fuel line from the wings should be routed to and teed into the header fuel sight guage at the bottom of the sight .Put an on/off in the dash so you can start and stop the transfer from wing tanks at will. This lets the bottom header tank on/off the whole sytem to the engine and gascolator but more importantly when you are transferring fuel to the header the sight guage fuel level will push upwards about 5" indicating that fuel is effectively siphoning into the header. when the wing tank stops flowing the sight gauge will return to the level in the header. I have found that fuel transfers only slightly faster than the engine burns it so overfilling is not likely. One last concern that makes me think the header tank is important is it lets you run the wing tanks dry for maximum safe fuel useage. Those of you that are using the big wing tanks. Put the tank on a 45 degree angle away from the outlet and see how much unuseable fuel you have. even at 1/2 the angle. You cannot safely fly a left hand circuit on the left wing tank unless it is nearly full since the pickup will possibly loose it's prime. It would be sad to run out of fuel when your tanks are not empty. Another advantage of my system is no wing tank gauges are necessary and I can use just the nose fuel for local flying or either of the wings when flying further In the interest of letting this subject end I would be glad to continue off the list for anyone interested. Dave Chesterman. 1996 701/582 220hrs made the 13 hr flight to oshkosh in 2001 ________________________________ Message 6 _____________________________________ Time: 09:07:31 AM PST US From: "W.R. \"Gig\" Giacona" Subject: Zenith-List: Re: Zenith-List Digest: 10 Msgs - 01/09/04 --> Zenith-List message posted by: "W.R. \"Gig\" Giacona" Have you ever visited Eastern Europe? If you want the plane quick this would be an excellent time. Kit a copy of the January 2004 issue of EAA's Experimenter. --> Zenith-List message posted by: "Kurt Johnson" Hey Fella's, My father and I are looking at building a 701 this summer. Neither of us has any experience with building aircraft or working with sheet metal and rivets. With this in mind; can two men, working 10-12 hours a day, 6 days a week, finish a complete plane with engine in one month? What things should we do to prepare for this effort. Obviously trying to get some hands on with sheet metal work would go a long way. Any advice will be much appreciated. Kurt Johnson --- ________________________________ Message 7 _____________________________________ Time: 01:23:22 PM PST US Subject: Re: Zenith-List: 28 volts vs 14 volts and electronics From: Ray Montagne --> Zenith-List message posted by: Ray Montagne On 1/11/04 6:55 AM, "Ron DeWees" wrote: > --> Zenith-List message posted by: "Ron DeWees" > > HI Bill, > I will hit a few rough spots in the discussion and let the gurus fill in the > gaps. > One big difference probobly isn't a factor for our small motors like the Zen > aircraft use. 28 volt systems can send larger currents further on smaller > wires than 12 volt systems. The current capacity on the wire is exactly the same. What is different is that a device consuming some number of watts will consume half the current at twice the voltage. For example, a device requiring 1 amp at 12 volts would consume 12 watts of power. A device consuming 12 watts of power at 24 volts would only require 0.5 amps. Ray Montagne, Cupertino CA ________________________________ Message 8 _____________________________________ Time: 02:59:24 PM PST US From: bryanmmartin@comcast.net Subject: Re: Zenith-List: Fuel Management update --> Zenith-List message posted by: bryanmmartin@comcast.net > --> Zenith-List message posted by: Chesterman Family > > Now for gravity feed from the wings. If you run fuel lines down the cabin > tubes, gravity will do its thing but that makes for an ugly system that you > must look at while flying so most run them down behind the seat as per the > plans and back up to the tank. > This is where gravity won't work on its own since a small amount of fuel > will lay in the bottom of the fuel line under the seat. When you refill the wing > tank the fuel does not have a high enough "weight" to push the fuel in bottom of > the line back up to the header tank so no fuel transfer so there has to be a way > to get the air out of the line from the wing tank to the floor. As long as no point in the transfer lines rises higher than the level of fuel in the wing tanks and the vent line is clear, there should be no problem getting fuel to feed to the header tank even with air in the lines. And you will need a drain at each low point. > > One last concern that makes me think the header tank is important is it lets you > run the wing tanks dry for maximum safe fuel useage. > Those of you that are using the big wing tanks. Put the tank on a 45 degree > angle > away from the outlet and see how much unuseable fuel you have. even at 1/2 the > angle. You cannot safely fly a left hand circuit on the left wing tank unless it > is > nearly full since the pickup will possibly loose it's prime. If you keep your turns coordinated, there should be no problem getting fuel to flow from the tank even in a steep bank with a low level in the tank. In fact it will flow better because of the increased G loading. The only time the fuel level the tank will be at an angle is if you are slipping the plane in on short final for runway alignment or to lose altitude quicker. At that point you should have the runway made even if you lose power. Bryan Martin ________________________________ Message 9 _____________________________________ Time: 07:34:49 PM PST US From: Chesterman Family Subject: Re: Zenith-List: Fuel Management update --> Zenith-List message posted by: Chesterman Family bryan-- you are wrong the column of fuel in the wing tank is 6" and the column of unused fuel to be pushed up to the header tank is about 16". therefore the fuel does not drain. this is why you have to open the bottom drain the increase the column of fuel which is air locked to flow down to the floor. 2nd-I will concede on the coordinated turn but you must be a better pilot than my friend and I as my wing tanks sometime do not completely empty (no problem for my system) but my friend uses the big tanks (no header, individual feed wing tanks) and has had the engine quit twice while in level cruise (he thought) with what he thought was ample fuel. I am trying to tell you what happens in practice---not theory dave bryanmmartin@comcast.net wrote: > --> Zenith-List message posted by: bryanmmartin@comcast.net > > > --> Zenith-List message posted by: Chesterman Family > > > > Now for gravity feed from the wings. If you run fuel lines down the cabin > > tubes, gravity will do its thing but that makes for an ugly system that you > > must look at while flying so most run them down behind the seat as per the > > plans and back up to the tank. > > This is where gravity won't work on its own since a small amount of fuel > > will lay in the bottom of the fuel line under the seat. When you refill the wing > > tank the fuel does not have a high enough "weight" to push the fuel in bottom > of > > the line back up to the header tank so no fuel transfer so there has to be a > way > > to get the air out of the line from the wing tank to the floor. > > As long as no point in the transfer lines rises higher than the level > of fuel in the wing tanks and the vent line is clear, there should be > no problem getting fuel to feed to the header tank even with air in the lines. > And you will need a drain at each low point. > > > > > One last concern that makes me think the header tank is important is it lets > you > > run the wing tanks dry for maximum safe fuel useage. > > Those of you that are using the big wing tanks. Put the tank on a 45 degree > > angle > > away from the outlet and see how much unuseable fuel you have. even at 1/2 the > > angle. You cannot safely fly a left hand circuit on the left wing tank unless > it > > is > > nearly full since the pickup will possibly loose it's prime. > > If you keep your turns coordinated, there should be no problem getting fuel to > flow from the tank even in a steep bank with a low level in the tank. In fact it will flow better because of the increased G loading. The only time the fuel > level the tank will be at an angle is if you are slipping the plane in on short final for runway alignment or to lose altitude quicker. At that point > you should have the runway made even if you lose power. > > Bryan Martin >