Stephen farrar Posted November 8, 2019 Share Posted November 8, 2019 Maiden flight of foamboard glider. Flying okay then 2 load bangs and it crashed in flames. 3 cell battery 30 amp esc 2240 kv motor. Any ideas what went wrong? Quote Link to comment Share on other sites More sharing options...
Dickw Posted November 8, 2019 Share Posted November 8, 2019 Not from the information given so far. What size prop? What size / type / capacity battery? Dick Edited By Dickw on 08/11/2019 15:56:17 Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted November 8, 2019 Share Posted November 8, 2019 Need more info. Current drawn at full throttle (if you don't know that, motor details and propeller size would probably allow someone to run it through a calculator) C rating of battery for a start. Edit: Dick was quicker on the (current ) draw... Edited By Martin Harris on 08/11/2019 16:00:06 Quote Link to comment Share on other sites More sharing options...
Stephen farrar Posted November 9, 2019 Author Share Posted November 9, 2019 Propeller was 8x6 battery 2200mah 25c Quote Link to comment Share on other sites More sharing options...
Frank Skilbeck Posted November 9, 2019 Share Posted November 9, 2019 Running a 2240kv motor on a 3s battery with an 8x6 prop through ecalc has it pulling 75 amps at WOT........... The motor KV is way too high, on a 3s battery it's trying to turn at over 17000 rpm.on an 8 x 6. The motor/ESC would be happier on a 6 x 4 prop, over 20000 rpm on a 3s battery though, around 25 amps. Perfect for a flying wing maybe, but for a glider then a lower KV motor turning a bigger prop would be the way to go. I'm running a 4max 1070 kv motor with a 12 x 8 prop on a 2200 mah 3s battery in my Multiplex Heron with a 40amp ESC, works well and no flames in over 2 years. Quote Link to comment Share on other sites More sharing options...
Dickw Posted November 9, 2019 Share Posted November 9, 2019 A 2240 kv motor on 3s will be trying to turn the prop in the region of 18,000 rpm which for an 8x6 prop suggest a current of 80 amps or more. I don't think a 30 amp ESC was adequate. The battery wouldn't like that for too long either. Dick edit - Frank was quicker this time! Edited By Dickw on 09/11/2019 12:09:16 Quote Link to comment Share on other sites More sharing options...
Stephen farrar Posted November 10, 2019 Author Share Posted November 10, 2019 Thanks for the advice. Building another one so will take your advise. Thanks again. Quote Link to comment Share on other sites More sharing options...
Trevor Crook Posted November 10, 2019 Share Posted November 10, 2019 Yep, my rule of thumb is around 1000kv for a 3s setup. Certainly worth investing in a wattmeter to avoid such mishaps. Quote Link to comment Share on other sites More sharing options...
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