Marko Posted July 6, 2008 Share Posted July 6, 2008 hello all ,,can you answer this quiry for me? when you ballance an IC plane (CG) you do it with an empty fuel tank! but with an eletric model do you ballance with the batt installed ? as when i flew my biplane under 3/4 power all it did was climb, the instrutions stated that it cg is 70mm from le and it hangs level without nose down attitude ..am i thinking right that i will have to put some down thust in to compansate this or add ballast to it instead? with no power it will glide dead flat without dropping,my plane is the multiplex gemini thanks .............. Quote Link to comment Share on other sites More sharing options...
David Ashby - Moderator Posted July 6, 2008 Share Posted July 6, 2008 Always balance with the battery Mark. Can't comment on the model but down-thrust would be preferable to adding weight I guess.... Quote Link to comment Share on other sites More sharing options...
birdy Posted July 6, 2008 Share Posted July 6, 2008 Always with the the battery, because the motora and esc are lighter then ic equiverlent so the designers put the pack in the nose to balence things out! Quote Link to comment Share on other sites More sharing options...
Chris Bott - Moderator Posted July 6, 2008 Share Posted July 6, 2008 If it glides fine and climbs under power then its downthrust you need definately. Ideally you want it's direction of travel to stay the same from glide right through to full power.It will of course gain height at full power and loose height when gliding, but that's not the same thing as the direction that the nose is pointing in.. Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted July 7, 2008 Share Posted July 7, 2008 MarkYou could check the actual position of the elevator when it is trimmed to glide. If there is a bit of "up" then you will get a noticeable nose up attitude under power from the prop wash over the tail plane. Rather than down thrust you could move the C of G back just a touch but don't over do it or you will crash! However if the elevator is truly in line with the tail plane when gliding then the C of G is probably correct & a bit of down thrust is the answer. Remember - always experiment in small steps. Quote Link to comment Share on other sites More sharing options...
Alan B Posted July 7, 2008 Share Posted July 7, 2008 Hi I have often always wondered this. With a electric powered model the C of G shouldn' t change unless you move the battery either forward or backwards.I have just built and yet to test fly my ic Kyosho 90 (damm weather and opportunity !). I have balanced the model as to the recommended C of G. However it has a large fuel tank upfront to supply the fitted 120 FS. So in theory you are adding a large amount of fuel upfront making it very nose heavy.So going back to Marks original question - ref ic models. full or empty? Or to a get a happy medium would it be better to balance the model with the tank half full - can somebody please express their views. I have a couple of smaller ic models and have balanced them empty as the manufactuers have never said anything different and have not had any problems. Depending on flying conditions I usually trim out accordingly anyway.I have a JR Venture 30 heli of which the tank is unusually fitted forward of the C Of G. It is a well known fact with these helis that when the tank is emptying you have to feed in forward trim. So I would presume the tank position on a heli is far more critical than on a aeroplane.any thoughts ?Al Quote Link to comment Share on other sites More sharing options...
Former Member Posted July 7, 2008 Share Posted July 7, 2008 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
Marko Posted July 7, 2008 Author Share Posted July 7, 2008 Thank s for the replies I will add a small amount of down thrust as glides straight and smooth without power so i guess the elevators are level , at the moment it will do huge power loops this problem was only noticed the other night it was a dead calm evening and it flu for 20 mins 2200 3s lipo well chuffed cheers again ..............mark Quote Link to comment Share on other sites More sharing options...
birdy Posted July 7, 2008 Share Posted July 7, 2008 Thats why the full size aircraft keep the fule in their wings! Quote Link to comment Share on other sites More sharing options...
Former Member Posted July 8, 2008 Share Posted July 8, 2008 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
birdy Posted July 8, 2008 Share Posted July 8, 2008 Sorry, ment fuel! Quote Link to comment Share on other sites More sharing options...
Yorkman Posted July 8, 2008 Share Posted July 8, 2008 surely just throttle back a bit more???? if you're climbing then you have excess power-full size saying is something along the lines of-elevator controls speed, throttle controls height. Quote Link to comment Share on other sites More sharing options...
birdy Posted July 8, 2008 Share Posted July 8, 2008 You do have a point there! The exception though is when you are building up speed for airobatics ect. or just trying to go fast! Quote Link to comment Share on other sites More sharing options...
Yorkman Posted July 8, 2008 Share Posted July 8, 2008 well, indeed! as you increase speed (forward stick/down elevator) so you need to increase throttle, and vice versa...that's flying as opposed to driving! Quote Link to comment Share on other sites More sharing options...
Marko Posted July 8, 2008 Author Share Posted July 8, 2008 thanks for all you advice but did some suggest to throttle back? sorry but i have a need for speed ha ha I've altered the angle of the elevator to slightly down but until it stops raining i cant check it oh well ill have to go buy something instead Quote Link to comment Share on other sites More sharing options...
Yorkman Posted July 8, 2008 Share Posted July 8, 2008 know what you mean about the rain.....if as you say your model 'glides dead flat' power off, then you need only a small amount of thrust to maintain height-you obviously have an excess, so enjoy!! Quote Link to comment Share on other sites More sharing options...
Marko Posted July 8, 2008 Author Share Posted July 8, 2008 Hi Yorkman i bought the tuned motor set from multiplex and I'm using the 10/6 prop which came with it so you could say Ive excess power ive not yet put any down thrust in yet but we will hopefully soon? cheers mark Quote Link to comment Share on other sites More sharing options...
Chris Bott - Moderator Posted July 9, 2008 Share Posted July 9, 2008 Surely if you have reset the elevator trim to slightly down, and put no downthrust in, you will still have the same problem? Except now it will dive in the glide.. Quote Link to comment Share on other sites More sharing options...
Former Member Posted July 10, 2008 Share Posted July 10, 2008 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
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