charlie holdford Posted May 5, 2021 Share Posted May 5, 2021 Hi All, I am practicing for the BMFA B test. I have several aircraft and can fly all the maneuvers badly. Some models are better than others at certain things. So my issue is with my Calmato Sport 40. I just can not get it to stall turn or even wing over. Almost as if it has no rudder.... But the rudder works when straight and level albeit with adverse roll Any idea as to why? Is it the C of G The Rudder size or servo not up to it I can perform this on my other models.... Cheers Charlie Quote Link to comment Share on other sites More sharing options...
Andy Stephenson Posted May 5, 2021 Share Posted May 5, 2021 Charlie, Before you modify anything try flying the stall-turn by putting on a short burst of throttle just as you apply the rudder, this will give it more authority. Quote Link to comment Share on other sites More sharing options...
Jon H Posted May 5, 2021 Share Posted May 5, 2021 As Andy suggests airflow over the rudder is likely the issue. You can try a burst of power but you can also try not bringing the throttle all the way back to idle. Work out what level of throttle is needed for a vertical climb and then use a throttle setting just below it. To prevent the climbing section being really long you may need to throttle back to near idle, and then slowly open up to your 'not quite enough to climb' throttle setting just before the model stops moving. Slap the rudder in with a bit of opposite aileron and it should go round. Quote Link to comment Share on other sites More sharing options...
john stones 1 - Moderator Posted May 5, 2021 Share Posted May 5, 2021 1 hour ago, charlie holdford said: Hi All, I am practicing for the BMFA B test. I have several aircraft and can fly all the maneuvers badly. Some models are better than others at certain things. So my issue is with my Calmato Sport 40. I just can not get it to stall turn or even wing over. Almost as if it has no rudder.... But the rudder works when straight and level albeit with adverse roll Any idea as to why? Is it the C of G The Rudder size or servo not up to it I can perform this on my other models.... Cheers Charlie How much movement you got on rudder Charlie, model looks well capable of doing em. Answer is most likely a combination of things. Have you upped the Rudder movement whilst trying ? Quote Link to comment Share on other sites More sharing options...
charlie holdford Posted May 5, 2021 Author Share Posted May 5, 2021 Hi Guys, thanks for the replies. I agree prop wash is needed, but even a wing over at full tilt doesn't make the thing go over.... John, I have three rate settings 100% (take of and landing) - 65% (normal flight) and 45% (just in case) used all of them to no avail. It is very strange Cheers Quote Link to comment Share on other sites More sharing options...
john stones 1 - Moderator Posted May 5, 2021 Share Posted May 5, 2021 And what's it like going vertical using much rudder to hold a line ? Elevator set at neutral or it got up trim in ? Quote Link to comment Share on other sites More sharing options...
charlie holdford Posted May 5, 2021 Author Share Posted May 5, 2021 Hi John, It tracks straight up without any rudder, unless its a crosswind. Elevator is relaxed at the top of the climb I then put in the rudder. either just after I kill the throttle. It changes end at the top i.e. comes nose down but not when or where I want it ? I have found with my other models it is easier to do a stall turn downwind but with this it makes no difference which way. Its almost laughing at me Quote Link to comment Share on other sites More sharing options...
john stones 1 - Moderator Posted May 5, 2021 Share Posted May 5, 2021 No, I meant is there uptrim in the elevator when sticks in the middle ? You went straight to C.G as the possible problem. Quote Link to comment Share on other sites More sharing options...
charlie holdford Posted May 5, 2021 Author Share Posted May 5, 2021 (edited) 12 minutes ago, john stones 1 Moderator said: No, I meant is there uptrim in the elevator when sticks in the middle ? You went straight to C.G as the possible problem. Sorry, a little I have moved the c of g back a little so I can get it to do the stall spin, Lets say the marked c of g is 80 -90 cms and I have it at about 95 cms Edited May 5, 2021 by charlie holdford correction Quote Link to comment Share on other sites More sharing options...
john stones 1 - Moderator Posted May 5, 2021 Share Posted May 5, 2021 Move it back then Charlie, trust yourself and alter things to suit your style, suggested throws and C.G points are starting points. You're 100% on Rudder give it full movement on the model ? 1 Quote Link to comment Share on other sites More sharing options...
charlie holdford Posted May 5, 2021 Author Share Posted May 5, 2021 OK John Will try it on Friday I think the weather is looking reasonable. If it works then I will need to use a different model for the test as I just couldn't get it to stall... typical 1 Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted May 5, 2021 Share Posted May 5, 2021 While you're trying things, have a go at following the advice to leave some throttle on as given in some previous posts. I'm sure you'll find it makes a big difference. While you've given us percentages, what are the actual deflections? 100% of not a lot won't be much use...it seems very odd that it won't do a wing over! What technique are you using? It would be a very ineffective rudder that wouldn't assist in performing a standard one. Quote Link to comment Share on other sites More sharing options...
Piers Bowlan Posted May 6, 2021 Share Posted May 6, 2021 16 hours ago, charlie holdford said: So my issue is with my Calmato Sport 40. I just can not get it to stall turn or even wing over. Almost as if it has no rudder.... But the rudder works when straight and level albeit with adverse roll Charlie, any control surface needs airflow to be able to apply a force. If the throttle is closed and the model is pointing vertically with no airspeed there will not be any airflow over the rudder. It is the same with a boat;- if there is no water flowing over the rudder you will not have any steerage. As others have said, either apply some rudder earlier while you still have a little airspeed or keep some power on to keep the rudder in the slipstream to maintain it's effectiveness. A big rudder also helps! Incidentally the further effects of roll is yaw and conversely the further effects of yaw is roll (How large these interactions will be vary, according to the design). As Jon says, use some opposite aileron to correct for any roll. Quote Link to comment Share on other sites More sharing options...
john stones 1 - Moderator Posted May 6, 2021 Share Posted May 6, 2021 Well as you've said you can stall turn other models, I'll take your word for it Charlie. Could still be your technique at fault though, best way to decide on that, is pass your box to a clubmate who can fly a bit, then take the advice of said clubmate. Models don't come out the box set to perform aerobatics, they require setting up to perform them well, get that part right then you can hone your technique and improve your skill set, part of which is setting up and trimming a model to help not hinder you. Quote Link to comment Share on other sites More sharing options...
Gary Manuel Posted May 6, 2021 Share Posted May 6, 2021 (edited) One thing that's not been mentioned and it caught me out with my first electric model. With an IC model, there is a small amount of thrust and therefore control authority even at tick-over. With an electric model, there is no thrust with the throttle closed. Could this be a factor here? Regardless of whether flying IC or electric, I think that stall turns look more graceful (slower and more controlled) if the throttle is only reduced to the point where it causes the model's climb rate to reduce and eventually stop, rather than chopping the throttle completely. Some of the best stall turns I've done are at full throttle with an underpowered model that runs out of steam in the climb, rudder applied at this point tips the model into a lovely stall turn. Edited May 6, 2021 by Gary Manuel Final paragraph added. 1 Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted May 6, 2021 Share Posted May 6, 2021 Thinking about that last statement, I’ve frequently done some reasonably decent looking stall turns on rudderless combat models. Just pull up to the vertical and as it slows with the throttle backed off allow it to yaw slightly with small secondary effect of ailerons and it rotates as it stalls. Quote Link to comment Share on other sites More sharing options...
charlie holdford Posted May 6, 2021 Author Share Posted May 6, 2021 (edited) Hi Guy, lots of good suggestions that I can try tomorrow. Compared with my other models, all plan built the Calmato is bigger and heavier, so maybe I am waiting too long before adding Rudder and therefore missing the momentum. Still good discussion. Cheers PS Martin, The Rudder throws are 35mm each direction at full rate. Some time ago I also increased the rudder size by an additional 20mm (aft) Edited May 6, 2021 by charlie holdford spelling Quote Link to comment Share on other sites More sharing options...
Gary Manuel Posted May 6, 2021 Share Posted May 6, 2021 (edited) 44 minutes ago, charlie holdford said: Hi Guy, lots of good suggestions that I can try tomorrow. Compared with my other models, all plan built the Calmato is bigger and heavier, so maybe I am waiting too long before adding Rudder and therefore missing the momentum. Still good discussion. Cheers PS Martin, The Rudder throws are 35mm each direction at full rate. Some time ago I also increased the rudder size by an additional 20mm (aft) Charlie, If you apply the rudder earlier in order to use momentum, then it is not a proper stall turn. Ideally a stall turn should be at virtually zero speed and the rotation should be around the CofG. If done with any degree of forward speed, the result will be a wing-over (Chandelle turn). If done too late, the result will be a tail-slide (possibly followed by a flop to the opposite side than you were expecting). A stall turn is somewhere between the Wing-Over and the Tail-Slide. Edited May 6, 2021 by Gary Manuel Quote Link to comment Share on other sites More sharing options...
ASH. Posted May 6, 2021 Share Posted May 6, 2021 Timing is important in a stall turn. Use the momentum on the upline just before the model comes to a complete stand still. It also matters which way you turn. 1 Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted May 6, 2021 Share Posted May 6, 2021 I do not claim to be any sort of aerobatic expert but if you let a model come to a complete stop in a vertical position and then close the throttle (electric) where is the airflow over the rudder coming from? Reduce the throttle to bring it stationary but as soon as it is increase the throttle back towards a 1:1 thrust to weight level as the rudder is applied. 1 Quote Link to comment Share on other sites More sharing options...
Denis Watkins Posted May 7, 2021 Share Posted May 7, 2021 (edited) 5 hours ago, Simon Chaddock said: I do not claim to be any sort of aerobatic expert but if you let a model come to a complete stop in a vertical position and then close the throttle (electric) where is the airflow over the rudder coming from? Reduce the throttle to bring it stationary but as soon as it is increase the throttle back towards a 1:1 thrust to weight level as the rudder is applied. Spot on Simon I fly both electric and I/C regularly And timing is different due to as you say " where is the airflow over the rudder coming from? " In the vertical position, with the throttle stick at " idle " my I/C motor is ticking over at 2000rpm giving off some air movement, where my electric motor at " idle " is at zero thrust. Stall turnTiming, and a mental note of leaving in some throttle is practiced. It is pretty much the same stick timing issue with an electric/ IC " touch and go" Where, On nearing the ground, throttle is progressively applied as to be ready to touch and go under power, before the wheels actually touch the ground. The I/C motor is already at 2000rpm moving air over the surfaces to maintain authority Where the electric motor goes through zero thrust if you move the throttle stick too low and stick timing needs to be practiced Both types of motor go to idle with the throttle stick fully down But the I/C motor still has some airflow over the surfaces, which is good for soul, flying and learning both types. Edited May 7, 2021 by Denis Watkins 1 Quote Link to comment Share on other sites More sharing options...
Ron Gray Posted May 7, 2021 Share Posted May 7, 2021 But then if you setup your leccy plane so that at idle it too is spinning at 2000rpm then it would behave the same as the IC. Added advantage is the breaking effect of the spinning prop. Obviously all on a switch if you want more control. Quote Link to comment Share on other sites More sharing options...
Dickw Posted May 7, 2021 Share Posted May 7, 2021 3 hours ago, Ron Gray said: But then if you setup your leccy plane so that at idle it too is spinning at 2000rpm then it would behave the same as the IC. Added advantage is the breaking effect of the spinning prop. Obviously all on a switch if you want more control. That is how I have my Pitts set up - throttle right back leaves the motor spinning at about 750 rpm. As well as providing prop braking it also improves throttle pickup from full back as the motor is already running and so it eliminates that slight delay as the ESC and motor synchronise. A side benefit of this is a continuous airflow even with the model stationary. That and the quicker throttle pickup for a quick blip probably help with the stall turns. I also have a locking switch as a "throttle OFF" switch to shut the motor down when required (or prevent it staring when not required!). Dick Quote Link to comment Share on other sites More sharing options...
Gary Manuel Posted May 7, 2021 Share Posted May 7, 2021 (edited) I'm wondering whether the slowly spinning prop on electric models also has a safety advantage. i.e. If it's spinning it's armed ? . If it's not spinning, it's disarmed ? . Just like an IC engine. It also forces you to disarm from the transmitter before the ESC livens up as most ESCs require throttle at zero before initiating. Easy to implement too on most systems i.e. throttle cut = -100 (ESC will initiate but not spin) but throttle travel limit = -85 (or whatever suits - throttle won't initiate but once initiated via throttle cut, will spin slowly at this setting). I might have a play and see whether I get on with this or not. Edit - It should also make failsafe easier to test as switching tranny off / on with motor armed but throttle at minimum will (should) result in motor stopping and starting. At the moment, I need to have throttle partly up so that I can see the motor stop when tranny switched off, but the motor won't restart when I switch back on because my tranny checks for throttle at minimum. Edited May 7, 2021 by Gary Manuel Failsafe note added. Quote Link to comment Share on other sites More sharing options...
Gary Manuel Posted May 7, 2021 Share Posted May 7, 2021 (edited) PS - apologies for thread drift. Nothing to do with Rudder Authority / Stall Turns, but hopefully useful to someone. Edit - regarding my previous edit, (which I can no longer edit due to 20 mins timeout) It won't be easier to test the failsafe because my tranny defaults my engine cut to OFF when it boots up. I would still need to press my switch for 3 seconds to rearm the motor. At least I wouldn't need to touch the throttle. Edited May 7, 2021 by Gary Manuel Quote Link to comment Share on other sites More sharing options...
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