Peter Jenkins Posted May 17, 2020 Share Posted May 17, 2020 Bit out of practice in sizing a tank for an OS 120 Surpass. It will be used in a Top Flite Mustang 60 which I estimate will weigh between 10 to 10.5 lb. I'd like a duration of 12-15 mins. My gut feel was around 300 ml tank might be a bit marginal and a 380 might do. Appreciate some guidance on my gut feeling. Thanks. Quote Link to comment Share on other sites More sharing options...
Jon H Posted May 17, 2020 Share Posted May 17, 2020 120 is a little excessive for that model. An 80 or 90 would be a better fit. If you use the 120, 12oz would be plenty unless you are using shed loads of nitro Quote Link to comment Share on other sites More sharing options...
john stones 1 - Moderator Posted May 17, 2020 Share Posted May 17, 2020 I had 16oz in mine Peter, I like a long flight and there was always a bit left in. Quote Link to comment Share on other sites More sharing options...
Richard Wills 2 Posted May 17, 2020 Share Posted May 17, 2020 My Hangar 9 Mustang 60 has a 120 Surpass, and a 20oz tank. Depends on how you fly it, mine is definately not flown in a scale manner and I would not want a smaller tank! Quote Link to comment Share on other sites More sharing options...
Peter Jenkins Posted May 18, 2020 Author Share Posted May 18, 2020 Thanks for your inputs guys. I get through an FAI aerobatic schedule in 7.5 mins and I cannot see me flying anything as complex as that with the Mustang. Jon has come in with a suggestion between my two tank sizes so I think I'll go with the 12 oz tank. Quote Link to comment Share on other sites More sharing options...
Jon H Posted May 18, 2020 Share Posted May 18, 2020 I use a 12oz on my laser 155. timer set for 8mins 30 so 10 mins by the time i am back on the ground with probably 5 minutes reserve for aborted landing. A friend has an os 120 in his kyosho 90 spit, seems very economical once we tuned up the slow run Quote Link to comment Share on other sites More sharing options...
Peter Jenkins Posted May 18, 2020 Author Share Posted May 18, 2020 That's very useful info Jon. Thank you. Quote Link to comment Share on other sites More sharing options...
Paul Marsh Posted May 18, 2020 Share Posted May 18, 2020 16oz. I have loads of SLEC Black 16oz ones. Ratios I use for engines are: .10 size: 2 oz .15 to 25 4oz .32. to .40 6oz 46 to 53 8oz 60 to 75 9oz to 12 75 to 90 14 oz 120 16 oz these are for two strokes, but a 4 stroke will give longer flight time Quote Link to comment Share on other sites More sharing options...
Bob Cotsford Posted May 18, 2020 Share Posted May 18, 2020 I'm pretty sure I used 14oz with my 120s as I had a stock of DuBro 14oz tanks that went in everything, I used to set my timers for 10 mins and never ran out, the OS120 Surpass's seemed to use less than my OS61SFs! Quote Link to comment Share on other sites More sharing options...
Former Member Posted May 18, 2020 Share Posted May 18, 2020 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
Jon H Posted May 18, 2020 Share Posted May 18, 2020 I used a 14oz on my 180 powered stampe. It was good for 15 minutes plus. 20oz on a 120? you will be up there all day! I have 22oz total capacity in my 300v equipped P39 and i barely use 2/3 over a 10 minute flight. Quote Link to comment Share on other sites More sharing options...
Bob Cotsford Posted May 18, 2020 Share Posted May 18, 2020 Doc, we are talking 4 strokes here. I could see 20oz for a big 2 stroke, my piped OS61SF in my Tornado used to drain a 14oz tank quicker than I liked and I landed on fumes a few times but the same size tank with a 120 4 stroke was another matter entirely. Quote Link to comment Share on other sites More sharing options...
Peter Jenkins Posted May 18, 2020 Author Share Posted May 18, 2020 Thanks again chaps. I've gone for a 12 oz tank. If I remember to, once the aircraft has flown, I'll report back on what happened! Quote Link to comment Share on other sites More sharing options...
Former Member Posted May 18, 2020 Share Posted May 18, 2020 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
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