danny_galaga Posted March 9 Author Share Posted March 9 (edited) 1 hour ago, RFguy said: dunno if I would use an SSR in that service The SSR must be rated at the stall current, which is probably 2 x the battery CCA ! Yeah, very rough guide for this sized starter is to allow maybe 500 amps. It's one of the reasons in the end I was happiest with a mechanical isolator over a relay. Pretty much no voltage drop or current draw. Every watt of energy to the starter. Faster starts, and battery recharges as quickly as possible 🙂 Edited March 9 by danny_galaga Link to comment Share on other sites More sharing options...
turboplanner Posted March 9 Share Posted March 9 5 pages and no answer? A 19 registered aircraft is supposed to be low cost, simple design, easy to build. The purpose of a cutout is to isolate the negative terminal of the battery from the electrics to prevent a fire on colliding, or suppress the source of an electrical fire. Therefore: (a) a battery isolator on a 19 aircraft should be required. (b) a mandatory word Solenoid should not be in the regulation (c) If the wording is battery isolator ther's not a problem requiring 5 pages (d) If the wording includes "solenoid" the questioner should write to RAA Ltd drawing their attention to this oversight and asking for it to be removed. 1 Link to comment Share on other sites More sharing options...
danny_galaga Posted March 9 Author Share Posted March 9 Technically a relay, not a solenoid. Solenoids are supposed to cause a mechanical movement too, for instance a solenoid attached to a starter moves a fork which pushes a pinion into a ring gear. Some starters don't have that system but a giant relay to just turn the starter on and inertia pushes the pinion into the ring gear (Lucas starters for instance) or it it just has a sprag clutch like our little BMW 650 starter. Because that relay is about as big and boofy as a solenoid (which doubles as a relay on a starter) some of us call them solenoids. So then any giant metal can relay ends up being called a solenoid.It's a bad habit! I mention it because you'll want to get the wording right when you contact them Turbo 🙂 1 Link to comment Share on other sites More sharing options...
RFguy Posted March 9 Share Posted March 9 the way it is described in the part91 / FAR USA regs is suitable, I will look it out. It describes the result / protection required, but not how it is acheived, IE as long as the intention is achieved. good regulation 5 1 Link to comment Share on other sites More sharing options...
Kyle Communications Posted March 9 Share Posted March 9 The SSR I posted is NOT for the starter motor to use it is only for the MASTER..which is for the internal DC for aircraft. The starter has a usual generic solenoid/relay to take the many hundreds of amps at start. I would never use it to switch starter motor current. Semantics of wether it is a solenoid or a relay is nit picking words...we all know what it is and what it does 2 Link to comment Share on other sites More sharing options...
danny_galaga Posted March 9 Author Share Posted March 9 (edited) 22 minutes ago, Kyle Communications said: The SSR I posted is NOT for the starter motor to use it is only for the MASTER..which is for the internal DC for aircraft. The starter has a usual generic solenoid/relay to take the many hundreds of amps at start. I would never use it to switch starter motor current. Semantics of wether it is a solenoid or a relay is nit picking words...we all know what it is and what it does A lot of this came about for me (I started this thread) because I was being lazy and wanted to know if I had to have an isolation relay/solenoid. People pointed out you really want to be able to fully isolate the battery in case of emergency (starter stuck in mesh, accident where positive cable shorts to airframe/engine, general electrical fire etc) Which it turns out that ssr is not big enough to do. So then it's kinda irrelevant. The starter key (off/on/start) on mine isolates everything but the battery from the cable already and now my battery isolator fulfills the emergency total isolation aspect. It's all interesting info though.And now my plane is much safer than when I started the thread. A good outcome 🙂 Edited March 9 by danny_galaga 2 Link to comment Share on other sites More sharing options...
Kyle Communications Posted March 9 Share Posted March 9 When referring to a Master in a aircraft it usually means the main electric buss for the internal DC for the aircraft. Not the whole system for the aircraft including battery. I believe what you wanted was a isolation switch. I will always have a isolation switch for the very reasons you give above, That really is a given. The master is not that. It is just wordings I suppose and it all just means take accepted practices for making safe the whole electrical system in the aircraft. How far you want to go with that is up to the builder...and the rules of course. There is no requirement for a isolation switch in any aircraft...but it just makes good sense because if a fault like that occurrs you cant just get out of the vehicle at 7000 ft...unless you got a parachute on 🙂 2 Link to comment Share on other sites More sharing options...
Blueadventures Posted March 9 Share Posted March 9 17 minutes ago, Kyle Communications said: When referring to a Master in a aircraft it usually means the main electric buss for the internal DC for the aircraft. Not the whole system for the aircraft including battery. I believe what you wanted was a isolation switch. I will always have a isolation switch for the very reasons you give above, Agree. Link to comment Share on other sites More sharing options...
Thruster88 Posted March 10 Share Posted March 10 Turning off the master in any certified VH aircraft definitely means isolation of the battery at the battery. 1 Link to comment Share on other sites More sharing options...
danny_galaga Posted March 10 Author Share Posted March 10 6 minutes ago, Thruster88 said: Turning off the master in any certified VH aircraft definitely means isolation of the battery at the battery. Yes, and it does that by switching off a big relay/solenoid. I'm very happy to have avoided that by just having a giant switch 🙂 And there can't be any confusion about what the switch does- it's big and red and has a picture of a battery on it 😄 1 Link to comment Share on other sites More sharing options...
onetrack Posted March 10 Share Posted March 10 (edited) Quote Semantics of wether it is a solenoid or a relay is nit picking words...we all know what it is and what it does Sorry, I have to disagree with this opinion. Technology is all about using correct, accurate technical descriptions for devices (or parts and components) to eliminate errors and confusion. A solenoid converts electrical energy into mechanical energy, converting electrical power into linear motion. A relay transfers current by allowing a low current circuit to control one or more higher current circuits. There is a major difference between the two devices, and it's not "nit-picking words". Many devices gain "common names" which are not correct technical names, and it may be O.K. to use these in casual face-to-face discussions where "local terminology" is understood - but correct technical naming must always be used in manufacturer references, written instructions and technical papers. Every manufacturer with a professional approach insists on this, and I have sighted and read numerous publications from companies that identify devices and parts by their correct names, and those publications insist that everyone use those correct names. Edited March 10 by onetrack expansion and clarification... 1 2 Link to comment Share on other sites More sharing options...
facthunter Posted March 10 Share Posted March 10 People don't know the difference between clearance tolerance and interference fit or bearing crush. Know the right terminology and cut the chance of confusion. Nev 2 Link to comment Share on other sites More sharing options...
Kyle Communications Posted March 10 Share Posted March 10 WEEEEELL it is semantics really. A relay is still a electromagnet coil and so is a solenoid. The solenoid is a much larger device designed to switch a much larger load and it does have a core that moves internally. The relay is pretty much exactly the same but in a smaller footprint and designed to handle a lot less current but it does the same thing. The relay though does tend to have a "switch" as contacts being NO and NC but there are exceptions where there is only one set of contacts which are NO similar to a solenoid. so it could be semantics or it could be definition..either way they both do the same thing. Yes you could have a solenoid working off a master switch in the aircraft that does isolate the battery. I have seen plenty of "solenoids" fail in my work life and to be honest I dont think I have ever seen a properly rated isolation switch fail. It is a peronal choice I suppose which way you want to go. To me I like the big manual switch right where it can be accessed from the pilot position. 1 1 Link to comment Share on other sites More sharing options...
facthunter Posted March 10 Share Posted March 10 They are NOT the same. A solenoid has anaxial moving armature capable of applying considerable force to an external mechanism and then making the contact after the force has done the moving. A relay allows a small current to close points and allow a heavier current to be applied in a heavier (usually shorter) circuit or just acts as a current sensing automatic switch . Nev 1 Link to comment Share on other sites More sharing options...
Kyle Communications Posted March 10 Share Posted March 10 Nev I know the differences of each to me its the same result. Just different purposes. After 43 years as a electrical fitter mechanic special class ( industrial electronics) and also a radio tech....I think I know what versions are used for what tasks. Working on 11kv and 33kv and 110kv circuit breakers...using solenoid style actuation and distribution authority electrical substation protection and control systems using hundreds of relays also fault finding and contruction of those substation controls..The last 10 years also doing design and development of mains connected power electronics for mass production sets of products to me they are essentially the same just a different scale and type for the purpose. As I said its semantics to me. You just use the APPROPRIATE DEVICE for the job. As I stated I much prefer to use a manual isolation switch within my reach in the cabin rather than a solenoid to isolate a battery that I have my arse sitting in. 1 Link to comment Share on other sites More sharing options...
facthunter Posted March 10 Share Posted March 10 Your electronics knowledge would be way ahead of mine but my activity working on auto and motorcycle and air craft starters generators and Alternators in a hands on and modification sense and 70 years of working on Magnetos, quite sufficient to base an OPINION on. . I doubt WE have ever disagreed on much if anything so that's it. Nev Link to comment Share on other sites More sharing options...
skippydiesel Posted March 10 Share Posted March 10 Seems to me that, in my lifetime, there has been a trend away from precise language - popular news media the likely source of the problem. EG "Petrol" seems to mean any liquid fuel used to power a vehicle. "Fertility" describes almost all matters associated mammalian reproduction. "Bathroom" covers facilities for depositing bodily waste and cleaning oneself. The all encompassing "Cessna" meaning a small aircraft. "Gay" no longer means happy and on and on 1 Link to comment Share on other sites More sharing options...
danny_galaga Posted March 11 Author Share Posted March 11 57 minutes ago, skippydiesel said: Seems to me that, in my lifetime, there has been a trend away from precise language - popular news media the likely source of the problem. EG "Petrol" seems to mean any liquid fuel used to power a vehicle. "Fertility" describes almost all matters associated mammalian reproduction. "Bathroom" covers facilities for depositing bodily waste and cleaning oneself. The all encompassing "Cessna" meaning a small aircraft. "Gay" no longer means happy and on and on Geez, how old are you? Gay has meant homosexual since the 1930s 😅 1 Link to comment Share on other sites More sharing options...
facthunter Posted March 11 Share Posted March 11 It used to be "Happy and GAY the Laxette way." Be as sloppy as you like with banter but in engineering Science and aviation care with detail and No confusion is what's REQUIRED Not optional. Otherwise YOU die and we get a bad reputation. and other things like bridges fail and you complain about that no doubt. . Nev 1 1 Link to comment Share on other sites More sharing options...
skippydiesel Posted March 11 Share Posted March 11 1 hour ago, danny_galaga said: Geez, how old are you? Gay has meant homosexual since the 1930s 😅 Not true - "Gay" may have been the way homosexuals described themselves, however it did not become the accepted meaning, amongst the wider community, until around the 1960-70's. Its change in meaning (now so narrow) is unfortunate, as its original meaning conveyed so much about someone state of mind, or the atmosphere in a get together, a tune, etc. 1 Link to comment Share on other sites More sharing options...
danny_galaga Posted March 11 Author Share Posted March 11 (edited) I don't care about what 'gay' means to anyone. The one that annoys me the most is AWESOME Having a particularly nice sandwich AND seeing a volcano blowing up and enveloping the town below in ash and lava cannot both be 'awesome'. Edited March 11 by danny_galaga 1 Link to comment Share on other sites More sharing options...
turboplanner Posted March 11 Share Posted March 11 15 minutes ago, danny_galaga said: I don't care about what 'gay' means to anyone. The one that annoys me the most is AWESOME Having a particularly nice sandwich AND seeing a volcano blowing up and enveloping the town below in ash and lava cannot both be 'awesome'. A person is overawed by each event so much that they are silenced. 1 Link to comment Share on other sites More sharing options...
skippydiesel Posted March 11 Share Posted March 11 I get particularly annoyed by the misuse of the word "Fertile" Fertile refers to an organism's potential to produce offspring. It can be applied to both genders. It should not be used to describe success or otherwise, in producing young. Nor can it be applied to a population (high/low) as, in the absence of some other factor eg like mass sterilisation, the population of breeding age, will remain fertile (within the normal distribution range). True there are situations where an individual will have low/nil fertility eg a human female after menopause, a castrated male, etc. Fertile can also be used to describe soil ie fertile soil has the potential to produces more plants/crop per unit area, than infertile soil. The correct term is fecund, fecundity. A male/female could, potentially have low fertility (few eggs/sperm), however due to opportunity, may have many offspring ie he demonstrate high fecundity. There is no such thing as a fertility rate but you can have a rate of fecundity. Google it and you will find an Americanised confusion of fertile/fecundity, pretty much purporting to mean the same thing - they do not. Example: Your spinster great aunt/uncle was not (necessarily) infertile because she/he chose not to marry and have children. On the other hand if you are one of many siblings, it could be said that your parents were, in the first instance, fertile, chose to maximise this potential and demonstrated considerable fecundity, by producing a small tribe of similarly named children. Link to comment Share on other sites More sharing options...
facthunter Posted March 11 Share Posted March 11 (edited) OF similarly "Brained" children.. It doesn't take Brains to procreate. There is a fair amount of evidence of the Brain not working at the time. Nev Edited March 11 by facthunter typo Link to comment Share on other sites More sharing options...
danny_galaga Posted March 11 Author Share Posted March 11 16 minutes ago, facthunter said: OF similarly "Brained" children.. It doesn't take Brains to procreate. There is a fair amount of evidence of the Brian not working at the time. Nev Life of Brian? He's not the Messiah, he's just a very naughty boy! 1 1 Link to comment Share on other sites More sharing options...
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