John Lee Posted July 3, 2023 Share Posted July 3, 2023 I went to a talk at the Royal Aeronautical Society a few years ago given by the head of Airbus's electric flight research section. If I recall correctly he said that their opinion is that whilst the will be incremental gains in battery efficiency, they could not see any prospect of a fundamental breakthrough. The reason behind this is that Lithium is number 3 in the Periodic Table (after Hydrogen & Helium) and its top left hand position position means that it has the highest useable negative electrochemical potential of any element, which is what drives battery efficiency. I don't have the knowledge to challenge or prove this assertion, but it does make some sort of sense. Yer cannot change the Laws of Physics (or chemistry), Jim! 3 Quote Link to comment Share on other sites More sharing options...
Paul De Tourtoulon Posted July 3, 2023 Share Posted July 3, 2023 5 hours ago, MattyB said: To each their own, but I personally can't understand how anyone can "love" the sound of a petrol two stroke, not matter how well they are silenced. I can acknowledge that any other engine has it's own certain charm, especially 4-strokes, but the bark of these two-stroke petrol weed whackers is so harsh and carries like nothing else - they have been responsible for so many noise complaints down the years. No thanks! I have a P40 with a Dle 20ra, and it's canister inside the fuselage, and it doesn't sound any worse than my Laser .90, I also have another dle 20 ra with twin 10€ boat silencers, it sounds more like an over silenced 10cc methanol of the 70's. Quote Link to comment Share on other sites More sharing options...
GrumpyGnome Posted July 3, 2023 Share Posted July 3, 2023 That's interesting - how much power do you think the boat silencers cost? Quote Link to comment Share on other sites More sharing options...
Paul De Tourtoulon Posted July 3, 2023 Share Posted July 3, 2023 Not a lot, but was it quiet,,,😇they are straight through tubes with no baffles, just a load of holes and some sort of silencing material inside. Quote Link to comment Share on other sites More sharing options...
GrumpyGnome Posted July 3, 2023 Share Posted July 3, 2023 Hmmmmm........ 1 Quote Link to comment Share on other sites More sharing options...
Chris Walby Posted July 3, 2023 Share Posted July 3, 2023 How far off topic can we go....Mod please delete 1 Quote Link to comment Share on other sites More sharing options...
Eric Robson Posted July 3, 2023 Share Posted July 3, 2023 Not much chance when the mod is showing home made silencers🙂😶. Actually the noise part of the thread would have been beneficial in the 10cc Stinger engine thread by Toto. 1 Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted July 3, 2023 Share Posted July 3, 2023 Yes, it has strayed a bit off the original topic but the OP was happy to introduce the subject of two stroke petrol engines at the top of page 3 and continue the conversation so I let it evolve. It would be a good time to get back on topic though as the diversion seems to be exhausted . My only experience of a LiPo fire - as opposed to release of smoke - was during a club visit to Germany where a clubmate's Spitfire met the ground rather terminally and set fire to the next door field resulting in some frantic activity with fire extinguishers to quell the flames from the burning vegetation. Luckily we had a quantity of slightly different Spitfires [from Shepherd Neames brewery] which, shared with the locals, helped douse any ill feeling! If anyone else has relevant content detailing first hand reports of LiPo fires then feel free to post but as the previous example was 2 pages/nearly2 days ago, perhaps it's not been a widely experienced problem? Quote Link to comment Share on other sites More sharing options...
john stones 1 - Moderator Posted July 3, 2023 Share Posted July 3, 2023 Only saw a few in the early days, as people learned better how to use them our club never sees them. Quote Link to comment Share on other sites More sharing options...
Chris Freeman 3 Posted July 4, 2023 Share Posted July 4, 2023 I have the t-shirt for this. Nearly 10 years ago our house was totally lost due to a lipo fire. 2 dogs died in the fire as well. This happened on a Saturday afternoon whilst my wife, son and I were at home. The fire was started by a 2 cell 2200 lipo which was used as a receiver pack on a giant scale Yak that belonged to my son. Brand new aircraft and charger that had been flown once. I am not sure exactly what caused the fire if it was a faulty battery, charger or user, but what I do know is that once a fire starts you have little hope of putting it out yourself. The other thing is how you will react in a situation like this. Our houses of full of highly flammable materials from carpets to curtains and furniture and the noise and smoke that a fire produces is also something that we will never forget. I do think that it is too easy to just think of a fire from a lipo but we have many things in our workshops and house that can cause a fire. We were left with just the cloths that we had on and that was it. No id's, bank cards or cars as the 2 not destroyed in the fire had the keys and spare keys burnt. 3 Quote Link to comment Share on other sites More sharing options...
Geoff Copping Posted July 4, 2023 Share Posted July 4, 2023 I witnessed a Lipo fire at our field about 18 months ago. Member was launching a large scale electric powered glider from a dolly. On leaving the dolly the glider stalled and landed with a bump on the grass field. A few seconds later a thick cloud of white smoke erupted from the cockpit followed by a belch of flames. By the time we could get to the club hut and then to the glider with an extinguisher then the fire had subsided. fortunately the fuselage withstood the inferno but much of the electrics forward of the wing were frazzled. It was more a heavy landing than a crash so it wasn't clear what had caused it. I've never witnessed a spontaneous lipo fire. Quote Link to comment Share on other sites More sharing options...
Dickw Posted July 4, 2023 Share Posted July 4, 2023 8 minutes ago, Geoff Copping said: I witnessed a Lipo fire at our field about 18 months ago. ...................... fortunately the fuselage withstood the inferno but much of the electrics forward of the wing were frazzled. .................. Sounds similar to my "in flight incident" described in the 4th post in this thread. I am getting the impression that newer Lipos don't burn as fiercely as the earlier generations of Lipo. BUT I am not planning to rely on that and no reason not to take sensible precautions. Dick Quote Link to comment Share on other sites More sharing options...
KenC Posted July 4, 2023 Author Share Posted July 4, 2023 Re off topic, I apologise to the technical purists that this topic of electrical propulsion went a little off the original fire topic, however I felt that flying is a wider concept with alternatives and repercussions. All of the alternatives relate to each other and so discussing one without looking at the alternative is rather blinkered IMHO. My take homes from this discussion so far, which was created to allow my mind and choice options to play , are 1) Electric fires seem to be primarily crash, historic equipment issues, or user error primarily. We seem to have got into better practice in general, partly caused by the horror stories. 2) Electric is not the cost saving alternative, other than possible long term costs of airframe degradation from oil contaminants. 3) Before I invite a Lipo into my life , I demand a Bat Safe as minimum and am in the process of arranging an external shed, living in a timber framed property this is essential. 4) I don't think I will ever completely walk away from IC, as I am a kid and rather like the vroom vroom . 5 Please will someone who is an expert produce a post for everyone's benefit showing how to correctly solder connectors and wiring as I still see this failure as an open door. 6) For the clubs flying close to agricultural land , liabilities and accidental fires need to be risk assessed before someone gets an enormous bill for a winter wheat field for example. 1 Quote Link to comment Share on other sites More sharing options...
MattyB Posted July 4, 2023 Share Posted July 4, 2023 (edited) 24 minutes ago, KenC said: 5) Please will someone who is an expert produce a post for everyone's benefit showing how to correctly solder connectors and wiring as I still see this failure as an open door. There are many, many pages and videos on this topic already - a quick Google got me a whole page full. This one seems quite comprehensive and has lots of embedded videos detailing methods for different connector types. More on the same site specifically focussed on soldering equipment and techniques. Edited July 4, 2023 by MattyB 1 Quote Link to comment Share on other sites More sharing options...
Andy Stephenson Posted July 4, 2023 Share Posted July 4, 2023 22 hours ago, John Lee said: Lithium is number 3 in the Periodic Table (after Hydrogen & Helium) and its top left hand position position means that it has the highest useable negative electrochemical potential of any element, which is what drives battery efficiency. When I worked alongside battery scientists, I asked the question, which elements would theoretically make the most energetic cell. The answer was a hydrogen/fluorine cell which would have a characteristic voltage of 6V. It would of course be impossible to build a cell that wouldn't instantly destroy itself but it would be interesting to try it, at a distance of course. 1 Quote Link to comment Share on other sites More sharing options...
John Lee Posted July 4, 2023 Share Posted July 4, 2023 On 01/07/2023 at 18:23, KenC said: Can someone tell me where they get ammo boxes from . From my distant memories all our 7.62 was in wooden boxes with sealed metal inners that were there more to keep things out. I guess water might be a bit like it is when dealing with phosphorus , it stops it until the air is returned. I've just noticed that Sussex Models have them in stock Link Quote Link to comment Share on other sites More sharing options...
KenC Posted July 4, 2023 Author Share Posted July 4, 2023 Thanks for the links, ammo boxes I have found quite a few now...seems the military are loosing and using a lot . Prices vary from £10 - £25 for moderate sizes and some deliver free ! As for the Ebay lessons , thanks for the link to the one you state as comprehensive. I always wonder with You Tube as the things I see teaching things I am good at I laugh about . Seems these days everyone is an expert ! lol So good to have someone that knows recommend. Quote Link to comment Share on other sites More sharing options...
Chris Walby Posted July 4, 2023 Share Posted July 4, 2023 I still have a serious concerns regarding the storage of batteries (of any type) inside a metal (conductive) box. Perhaps totally unfounded as everyone who buys an ammo box lines it with a non conductive, non flammable material, but what I have seen this is not always the case. Accident waiting to happen IMO. Quote Link to comment Share on other sites More sharing options...
KenC Posted July 4, 2023 Author Share Posted July 4, 2023 49 minutes ago, Chris Walby said: I still have a serious concerns regarding the storage of batteries (of any type) inside a metal (conductive) box. Perhaps totally unfounded as everyone who buys an ammo box lines it with a non conductive, non flammable material, but what I have seen this is not always the case. Accident waiting to happen IMO. Anyone got an old fire blanket ? 1 Quote Link to comment Share on other sites More sharing options...
john davidson 1 Posted July 4, 2023 Share Posted July 4, 2023 As previously said storage is not a problem, charging, shorting and damage from crashing is. 4 Quote Link to comment Share on other sites More sharing options...
MattyB Posted July 4, 2023 Share Posted July 4, 2023 2 hours ago, Chris Walby said: I still have a serious concerns regarding the storage of batteries (of any type) inside a metal (conductive) box. Perhaps totally unfounded as everyone who buys an ammo box lines it with a non conductive, non flammable material, but what I have seen this is not always the case. Accident waiting to happen IMO. For this reason I line mine with old plastic milk cartons with the top potion cut off - the fit perfectly, surround the packs to stop them rattling around in stransit, and prevent a short occurring. The lid jsut gets covered in a few layers fof tape and voila, all done. Quote Link to comment Share on other sites More sharing options...
GrumpyGnome Posted July 4, 2023 Share Posted July 4, 2023 4 hours ago, KenC said: 6) For the clubs flying close to agricultural land , liabilities and accidental fires need to be risk assessed before someone gets an enormous bill for a winter wheat field for example. BMFA Insurance covers this.... Quote Link to comment Share on other sites More sharing options...
KenC Posted July 4, 2023 Author Share Posted July 4, 2023 (edited) 20 minutes ago, GrumpyGnome said: I have always found with ageing eyes and 2 point typefaces , there is always a clause of due diligence and shortfalls. Edited July 4, 2023 by KenC Quote Link to comment Share on other sites More sharing options...
GrumpyGnome Posted July 4, 2023 Share Posted July 4, 2023 Absolutely. If, for example, your farmer landlord asks you for a no-fly zone, and then someone crashes into it and starts a fire, you'd likely have a fight on your hands Quote Link to comment Share on other sites More sharing options...
aidan mcatamney Posted July 7, 2023 Share Posted July 7, 2023 (edited) On 01/07/2023 at 12:01, KenC said: As , so far, a purely IC flyer going back to my first trainer for RC and Baby Bee for control line as a kid , this electric thing has made me a little nervous. There are stories all over and everyone says they know someone , yes I Googled this site , but what I want to know is WHO HAS FIRST HAND experience of a lipo fire ? What do you believe was the cause , and what have you done or learned since that experience ? I guess there must be quite a few members here that fly electric, so lets see just how prevalent this experience is. PLEASE no " I knew a guy" stories , first hand only. Unfortunately I have first hand experience of a lipo fire. It was that bad it burned 80 percent of my house to the ground. My elderly aunt who was on a walking frame that also lived in the house was lucky to escape with her life. I wasn't at home but had left a 3s lipo battery charging on a brand new charger I had just bought. It all happened on Friday 13th of July 2007. When I got home I found my house surrounded by two fire engines, an ambulance and a large crowd of people. It was a nightmare. During the fire my aunt was able to make her way to the front door where she was rescued by two workmen. We were out of the house for 5 months until the renovation work was completed. Luckily the house insurance covered everything but more importantly my aunts life was saved. The battery charger seemingly was to blame as it didn't cut off when the lipo was fully charged and the lipo exploded with devastating consequences. I will never forget it and always warn people when charging lipo batteries to never leave them unattended. Since 2007, I've been charging lipos constantly without a problem. Edited July 7, 2023 by aidan mcatamney 1 Quote Link to comment Share on other sites More sharing options...
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