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Title: How much of a thrust is sufficient to takeoff a plane and fly it normally? Post by: ashutoshn on May 17, 2011, 08:41:44 AM Well I was under the impression that if a plane has all up weigh (AUW) of 200gms then thrust of 220 - 300gms range is sufficient to fly it in normally. Anything less than 200gms and the plane wont even take off the ground.
Came across this thread which proves me otherwise ;D http://www.rcpowers.com/forum/showthread.php?2286-My-Blu-Baby&p=17401#post17401 So now the question is: What should be the general thumbrule for weight to thrust ratio for any given airplane? Also does the type of plane such as trainer, low winger, delta wing, f-22, odd shapes such as snow-ball, etc have an effect over thrust weight calculations :thumbsup: Title: Re: How much of a thrust is sufficient to takeoff a plane and fly it normally? Post by: dinil on May 17, 2011, 08:50:34 AM check this thread
http://www.rcindia.org/electric-power/amp-rating-and-motor-size/ Title: Re: How much of a thrust is sufficient to takeoff a plane and fly it normally? Post by: anwar on May 17, 2011, 08:51:27 AM The thrust requirements for various types of aircraft are listed in the first post of this thread :
http://www.rcindia.org/beginners-zone/selection-of-power-system-and-components/ Title: Re: How much of a thrust is sufficient to takeoff a plane and fly it normally? Post by: sultan alam on May 17, 2011, 08:52:39 AM NO, the thrust should greater than the weight of the plane is not always true.It is applicable in the case of heli and 3d plane.
A plane having good wing shape with light weight and thrust 20 % less than the weight of the plane can fly.I am not telling u any theory ,I have done some experiment on my plane using several size of propelleller. Title: Re: How much of a thrust is sufficient to takeoff a plane and fly it normally? Post by: avijit17basu on May 17, 2011, 09:38:28 AM The trust acts in the horizontal direction and is opposed by drag.
The weight acts vertically downwards and is opposed by lift. The lift MUST exceed the weight for the plane to fly. laws of physics. The lift depends on the airspeed and airfoil shape and wing area. Remember Gliders and kites fly with zero thrust. Read up the basic principles of flight. Thrust more than weight is required for unlimited vertical flight. Even in jet fighters the thrust is ussually less than weight. A airbus A380 certainly does. In a rocket the thrust definitely exceeds weight. regards Avijit Title: Re: How much of a thrust is sufficient to takeoff a plane and fly it normally? Post by: CrazyPilot on May 17, 2011, 09:40:32 AM hope this helps
http://www.rcindia.org/electric-power/a-basic-guide-to-electric-flight/ Title: Re: How much of a thrust is sufficient to takeoff a plane and fly it normally? Post by: AEROVISHWA on May 17, 2011, 01:27:47 PM the thrust required depends upon the following factors...
weight of the plane aerofoil shape of the main wing aerofoil shape of the tail plane amount of drag created total lift created by the wing (wings in case of bipe) location of the wing thickness of the wing shape of the leading edge location of the thrust provider ( pusher or puller..... els prop or jet or on the wings) thrust line etc etc(will update as i remember) :salute: :salute: :salute: Title: Re: How much of a thrust is sufficient to takeoff a plane and fly it normally? Post by: azhaguvel on May 17, 2011, 06:14:33 PM I am making a rcpowers 300 using coro and the weight turned out to be 350gms(everything including electronics) and the motor is capable of around 600 gms. will it fly(the wing span is 35.5")?
Title: Re: How much of a thrust is sufficient to takeoff a plane and fly it normally? Post by: sultan alam on May 17, 2011, 07:00:03 PM the motor is capable of around 600 gms. Can't understand this line .Is it thrust? Title: Re: How much of a thrust is sufficient to takeoff a plane and fly it normally? Post by: azhaguvel on May 17, 2011, 07:36:59 PM yes its thrust.
motor: 2210N 1000Kv Brushless Motor GWS9050 @3S Max Amp: 11.2A RPM/Min: 8700 Thrust: 740g Title: Re: How much of a thrust is sufficient to takeoff a plane and fly it normally? Post by: sultan alam on May 17, 2011, 07:47:51 PM Yes definitely it will fly .
Title: Re: How much of a thrust is sufficient to takeoff a plane and fly it normally? Post by: abhay on May 17, 2011, 08:21:31 PM Just talking in layman terms:
Consider you are pulling up a rolling bag on a ramp.I hope you must have done it while travelling. So, its quiet easier to roll it on a ramp with very less slope(say 15 degrees). If the slope is more(say 40 degree), you need more thrust to pull it. And if you are just lifting it(slope is 90 degrees), you need the thrust just a bit more than the weight of the bag.. So, here flying is like just going on a air ramp, angle of attack being the slope of ramp. Abhay Title: Re: How much of a thrust is sufficient to takeoff a plane and fly it normally? Post by: ashutoshn on May 17, 2011, 09:59:38 PM Thanks all for your replies. Actually i was expecting some formula for weight to thrust ratio. But guess there are multiple factors including location and thickness of the wing.
Came across a URL which calculates the theoritical thrust. In this URL i think the trick is to keep the Motor efficiency around 75-80% and if the thrust is around +/-20% of AUW then you got a decent flyer. http://www.badcock.net/cgi-bin/powertrain/propconst.cgi?C_prop=123&RPM=&Volts=8&Current=8&Watts=64&Height=20&Temp=28 |