Dave Hopkin Posted August 22, 2014 Share Posted August 22, 2014 Ok, tried a new plane out this morning My plan was to do a few ground runs on my (first tail dragger) to see that it taxied in a nearly consistent fashion..... But the thing decided that ever decreasing circles were a better option Check undercart all square, wheels run smoothly - other things I am not sure off 1) I fitted a larger prop (12" 2) Not sure of the offset/downthrust values for this one Any bright ideas? Quote Link to comment Share on other sites More sharing options...
Dave Bran Posted August 22, 2014 Share Posted August 22, 2014 Taildragger tendency to ground loop is a "feature" of some designs. 1. Careful use of rudder and throttle should avoid it. (Stabbing the throttle open is usually on most TD's destined to cause a loop) 2. Toe the wheels OUT slightly. Quote Link to comment Share on other sites More sharing options...
Dave Hopkin Posted August 22, 2014 Author Share Posted August 22, 2014 OK, I will try that, though she didn't actually ground loop., wings stayed pretty level (I was on quite low power, doing a ground run with no intention of rotating) she just wanted to turn to the left (from behind - prop running clockwise from behind) I'll try the toe out, though its a dural undercart so not going to be dead easy Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted August 22, 2014 Share Posted August 22, 2014 Dave Low power taxiing on a tail dragger is not easy as they will tend to turn and you don't really have enough airspeed for the controls to work effectively. You will need quite a bit of power (to get prop wash over the rudder) along with big rudder movements to keep on top any turning tendency. Control will get better the faster you go particularly once the tail is up but as soon as you shut the throttle to slow down you have no prop wash on the rudder and guess what is quite likely to happen! In some respects with a tail dragger once at speed you might as well take off! Of course a trike undercarriage with a steerable nose wheel you can drive about like a car if you want to! Quote Link to comment Share on other sites More sharing options...
Dave Hopkin Posted August 22, 2014 Author Share Posted August 22, 2014 Yup I can taxi my trike round (divots excepted) reasonably well now, this tail dragger does actually have a steerable tail wheel, so I was expecting a little less chaos when I taxied her Quote Link to comment Share on other sites More sharing options...
Steve Ashton Posted August 22, 2014 Share Posted August 22, 2014 Hi Dave, Check your tail wheel is 'tracking' straight with rudder straight and check tightness of main wheels is as similar to each other as you can without them behaving as a brake and also no sloppy wheel wobble. I've had both with a new plane, check it out without engine running, find a smooth surface and set rudder/wheel straight and just simply hand push the plane, see if it turns then and adjust as needed. Quote Link to comment Share on other sites More sharing options...
john stones 1 - Moderator Posted August 22, 2014 Share Posted August 22, 2014 Check your tailwheel is straight Dave, even bend if needed to get it to track straight, also have you enough rudder/ tailwheel movement for steering ? It's a knack flying taildraggers you'll get it John Quote Link to comment Share on other sites More sharing options...
Chuck Plains Posted August 22, 2014 Share Posted August 22, 2014 Always chuck your planes. Quote Link to comment Share on other sites More sharing options...
iqon Posted August 22, 2014 Share Posted August 22, 2014 Had same problem once, needed small amount of weight adding to tail, made all the difference.. Quote Link to comment Share on other sites More sharing options...
Josip Vrandecic -Mes Posted August 22, 2014 Share Posted August 22, 2014 Dear Dave,for tail dragger ,among others needs at least two things......a high set two front wheels and a flat preferably tarmac track. happy takeoff and landing Jo Edited By Josip Vrandecic -Mes on 22/08/2014 20:34:02 Quote Link to comment Share on other sites More sharing options...
DH 82A Posted August 22, 2014 Share Posted August 22, 2014 If you have a steerable t/wheel, and are taxying around, hold full up on elevator. For take off, hold full up and steer with rudder, as speed increases ease off on elevator allow tail to rise to flying position. When flying speed is reached, gently apply up elevator, and model will take off. Quote Link to comment Share on other sites More sharing options...
Dave Hopkin Posted August 22, 2014 Author Share Posted August 22, 2014 Thanks guys, some useful input and things to check, if none of those work, I might be forced to read the instructions...... The ones that jump out (ie I havent checked) Wheel wobble/braking effect I might also move the CofG back too Quote Link to comment Share on other sites More sharing options...
Allan Bennett Posted August 23, 2014 Share Posted August 23, 2014 I second the advice about holding full up elevator until you've got up a bit of speed. By pushing the tailwheel or skid into the ground it stabilises the direction of travel. Don't hold 'up' for too long though, otherwise the model will try to take off before it's got enough airspeed. By the way, since you mention "motor", is your model electric powered? If so, make sure you check with a meter to make sure you're not over-amping something when you change prop size. Quote Link to comment Share on other sites More sharing options...
Dave Hopkin Posted August 23, 2014 Author Share Posted August 23, 2014 Yep it is an electric, and will do.... Quote Link to comment Share on other sites More sharing options...
Peter Miller Posted August 23, 2014 Share Posted August 23, 2014 I wonder what the model is? If the undercarriage is too far forward it will make the model ground loop. Some Vintage models were notorious for this. In our club almost every model is a tail dragger and we fly off grass. never have any problems. Quote Link to comment Share on other sites More sharing options...
Dave Hopkin Posted August 23, 2014 Author Share Posted August 23, 2014 Well so far I have (I hope) corrected two faults.... 1) The port wheel was quite sloppy while the starboard was firm, that may have been contributing to the port wheel it wanted to do under power 2) The instructions specified 2mm downthrust on the adjuster set screws (3.5mm top and 2mm bottom), when I took the motor out the port upper set screw was at about 2mm while the starboard upper was at 3.5, the lower 2 set at the correct 2mm - this would have given me a few degrees of side thrust to the port side it now pushed along in a straight line with no power and when test on a very short run seem to run true... We shall wait for the weather/wife to permit another bash at the field...... Thanks for the advice guys Quote Link to comment Share on other sites More sharing options...
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