ifan jones Posted January 20, 2013 Share Posted January 20, 2013 hi, I am working toward my B grade with a fixed wing aircraft. Im not sure on how to do the spin. Can anyone tell me what inputs I need to put on the stick? thanks Ifan Edited By ifan jones on 20/01/2013 16:26:18 Quote Link to comment Share on other sites More sharing options...
Chris Bott - Moderator Posted January 20, 2013 Share Posted January 20, 2013 We're bound to get some different opinions here ifan but as the B test schedule says something about no flick entries then let's have a go. I think the spin should be entered by slowing the model down gradually with the elevator, and at the point of the stall, bang in full rudder and keep full rudder and up elevator held in. There should be no need for aileron input. Most models will leave the spin simply by centering the controls again, however rotation may continue a little, so this has to be timed right if you want to come out at the correct heading. Edited By Chris Bott - Moderator on 20/01/2013 16:47:42 Quote Link to comment Share on other sites More sharing options...
Peter Christy Posted January 20, 2013 Share Posted January 20, 2013 Chris is spot on - a gentle stall with full rudder and up elevator applied as it stalls. Too steep a stall will often stop it entering a spin. BUT: (there is always a but, isn't there!) most models are designed with a slight excess of stability, and can be tricky to get to spin. Many will spin one way, but not the other, so try both directions! It often helps to keep the throttle open a crack to increase the draft over the tail surfaces! If it still won't spin, try a bit more elevator travel - or move the CG aft a bit. Be careful with this last one, as if you take it too far, you risk making the model unstable. Most models will recover as soon as you let go of the sticks. However, some scale models may require a good dab of down elevator (to unstall the stalled wing) with maybe a dab of opposite rudder, if it is *really* reluctant to recover. The latter is rare though. In nearly 50 years of flying RC, I've only ever encountered two models that required opposite rudder as well! Try it at a good height the first time! -- Pete Quote Link to comment Share on other sites More sharing options...
ifan jones Posted January 20, 2013 Author Share Posted January 20, 2013 hi, chris, pete thankyou both for helping, Ifan Quote Link to comment Share on other sites More sharing options...
GrahamC Posted January 20, 2013 Share Posted January 20, 2013 Ifan. It's well worth downloading and printing off this the guidance notes for the B test. Don't go on what is written in the BMFA handbook as it only gives you the briefest overview and no ideas about what is acceptable and what is not. I'm nearly ready for my test, but have a WOT4 that is very very reluctant to spin. It's well trimmed in all other respects, but really really doesn't want to drop a wing. The examiner should be looking to see that the high wing does not rise as the plane begins to spin. That would be a flick entry and the aircraft is not really stalled. When my WOT4 does spin properly it rotates much faster than it does from a flick entry, and it's more difficult to get the timing right and exit after three spins. As I said, the notes are very helpful. Also, one of our club examiners has been up at the field on his own on a number of occasions and put me through a fake test. It has been very helpful to get his feedback about what I need to work on. I used to think that the double roll was the hardest thing to do, but I'm beginning to think its the figure of eight! Especially if its blowing! I've really enjoyed the discipline of practicing for the test and am thinking about dipping a toe in pattern flying as a way of hving something to aim at in the future. Quote Link to comment Share on other sites More sharing options...
Biggles' Elder Brother - Moderator Posted January 20, 2013 Share Posted January 20, 2013 I would agree with what Chris and Pete say. One addition, a lot of models will naturally drop one wing slight going into the stall - thats because of inevitable small errors in wing form/incidence/a million other small things (!) will tend to make one wing stall a fraction before the other. If the model does this you'll usually find its the same wing that drops first everytime. Its obviously easier to spin "into" that wing than the other way. So, as the B doesn't specify which direction you have to spin in, you can help youself a tad here. Practice getting to the gentle stall and note which wing (if any) goes down first, and then once you have a established that, do your spins predominately in that direction. Its not cheating, its just taking advantage of the aircraft's natural tendancies. Some models are very fussy about the spin - I have a little PZ Extra that if you move the battery just a tad to far forward wont spin at all! Move it back a bit - literally just a 1/4" or so - and it will spin really well. Final point - be careful to be sure that you do have a fully developed spin and not a spiral dive. A good examiner will spot the difference a mile off. In a proper spin; the wing will be stalled and the model will auto-rotate more or less about axis throught its CoG position. In a spiral dive the wing is not stalled and the rotation will be about an axis which is generally outside of the volume of the model. BEB Quote Link to comment Share on other sites More sharing options...
Keith Simmons Posted January 20, 2013 Share Posted January 20, 2013 I have never tried spinning a model yet, and am still learning. However in a full sized glider, I do a slow turn and slow down till the wing drops, entering into a spin. Is that not acceptable? An opposite rudder gets me out of the spin. Quote Link to comment Share on other sites More sharing options...
Biggles' Elder Brother - Moderator Posted January 20, 2013 Share Posted January 20, 2013 Its fine for general flying, but not for a B I'm afraid Keith. If I remember correctly the rules say it has to be entered from level flight. The model shouldn't actually be stalled at the point of entry - it should be just about to stall - its the input of the rudder that should actually "push it over the edge". BEB Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted January 20, 2013 Share Posted January 20, 2013 Yes - remember that it should exit on the same heading as the entry. Quote Link to comment Share on other sites More sharing options...
Biggles' Elder Brother - Moderator Posted January 20, 2013 Share Posted January 20, 2013 I seem to remeber there is a few degrees of latitude on that Martin? Am I right? 10-20 degrees or so? BEB Quote Link to comment Share on other sites More sharing options...
cymaz Posted January 20, 2013 Share Posted January 20, 2013 Yep sounds like all good advice. Find out which way the plane wants to tip on the stall and go that way. I used some aileron and rudder to get the spin going then controlled the spin rate with the ailerons only. But that was probably my plane characteristics. Try one or two then move onto 3. Quote Link to comment Share on other sites More sharing options...
Biggles' Elder Brother - Moderator Posted January 20, 2013 Share Posted January 20, 2013 You have to be careful using ailerons because, for the B at least, you mustn't be seen to be initiating the spin with the ailerons. You can put them in once the fall into the spin has started - but not before. BEB Quote Link to comment Share on other sites More sharing options...
cymaz Posted January 20, 2013 Share Posted January 20, 2013 ooooooooops...........sorry Quote Link to comment Share on other sites More sharing options...
Biggles' Elder Brother - Moderator Posted January 20, 2013 Share Posted January 20, 2013 Hi Cymaz - no need to apologise - what you said is fine - using the ailerons to control the spin like you suggest is fine - I was just stressing that you can't preceed the spin with them for the B. BEB PS Having said that in a fully developed spin, with the wing stalled, the ailerons are often of limited use! Edited By Biggles' Elder Brother - Moderator on 20/01/2013 21:10:30 Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted January 20, 2013 Share Posted January 20, 2013 A lot of full size gliders actually require out-spin aileron to spin - the additional drag/increased AoA from the downgoing aileron overcoming some of the washout effects. There is some small latitude in the exit heading but it should be within 10 or 15 degrees of the entry heading and corrected during the pull-out. Quote Link to comment Share on other sites More sharing options...
cymaz Posted January 20, 2013 Share Posted January 20, 2013 I did pass my "B" a couple of years ago. Ifan, it took alot of concentration and lots of work. I'm not putting you off but it is a step up from an "A". Quote Link to comment Share on other sites More sharing options...
Tim Cheal Posted January 20, 2013 Share Posted January 20, 2013 Ifan I am not sure if you are a subscriber (and by the way I am in no way affiliated to RCM and E) but RCM and E explored how to pass the B Exam some years ago. The articles were written by Andy Ellison in Feb 2008, Apr 2008, Jun 2008, July 2008 and a discussion on the dreaded questions in Sep 2008. The spin itself was specifically covered in June 2008. I have not myself done the B yet, but have done some pre exam preparation and I found the articles very useful (thanks Andy if you are on the forum). Tim Cheal Quote Link to comment Share on other sites More sharing options...
ifan jones Posted January 21, 2013 Author Share Posted January 21, 2013 thanks every one been great help! Quote Link to comment Share on other sites More sharing options...
David Ashby - Moderator Posted January 21, 2013 Share Posted January 21, 2013 Posted by Tim Cheal on 20/01/2013 22:22:26: Ifan I am not sure if you are a subscriber (and by the way I am in no way affiliated to RCM and E) but RCM and E explored how to pass the B Exam some years ago. The articles were written by Andy Ellison in Feb 2008, Apr 2008, Jun 2008, July 2008 and a discussion on the dreaded questions in Sep 2008. The spin itself was specifically covered in June 2008. I have not myself done the B yet, but have done some pre exam preparation and I found the articles very useful (thanks Andy if you are on the forum). Tim Cheal The articles are all in the digital archive and, I'd say, definitive reading for any aspiring 'B' pilot. Quote Link to comment Share on other sites More sharing options...
Mr.B. Posted February 6, 2013 Share Posted February 6, 2013 Picking up from Ifan's question. I've also been practicing spinning for the cert B (Wot 4e, balsa). I've read the BMFA hand book, Guidance notes and the RCME articles. In his article Andy says that you must complete 3 turns and only 3 turns. My question is as during the first rotation the plane won't be in a full developed spin does the first turn count? I didn't realise counting to three would be so hard. Quote Link to comment Share on other sites More sharing options...
Biggles' Elder Brother - Moderator Posted February 6, 2013 Share Posted February 6, 2013 My understanding is you count everytime the nose passes the entry direction - so yes, the first turn counts. But I'm not an examiner - maybe one would like to comment? BEB Quote Link to comment Share on other sites More sharing options...
John Hickson Posted February 7, 2013 Share Posted February 7, 2013 Just so I understand...... Why cant a spin be an aileron spin? Is it just so you understand how to induce a spin with something other than ailerons? Is there something to be learnt from this - a recovery technique maybe? Quote Link to comment Share on other sites More sharing options...
cymaz Posted February 7, 2013 Share Posted February 7, 2013 this will help, look at page 10. These are the examiners notes. Quote Link to comment Share on other sites More sharing options...
Biggles' Elder Brother - Moderator Posted February 7, 2013 Share Posted February 7, 2013 I think the rationale for including the spin in the B isn't entirely about the spin itself - if you know what I mean! The test is not just about "can you induce a spin and recover from it?". Its at least in part because a classically rudder induced, correctly performed, fully developed spin is a very good test of aircraft control. The point here is to take the aircraft very close to the stall but not at it and then judge the moment at which the addition of side slip from the rudder will be just enough to push it over the edge into the stall one wing dropped (note - one wing dropped, not the other wing lifted!). Put in the rudder too soon and you just end up with an untidy side slipping model that will stall some moments later and may, or may not, enter a spin. Too late and the stall will have happened and you probably wont get the "one wing first spin entry" followed by a true spin. The use of ailerons blurs things. In stead of pure stall induced wing drop we may very well get simply wing bank - ie one goes down and one goes up. In the worse cases there is no true stall and what you end up with is a spiral dive not a spin. Even in cases where there is a stall and a subsequent spin, its much easier to induce the one wing tip stall with the ailerons and so the timing is less critical, which in turn means that a lower level of aircraft control skill is needed. Finally we should note that the rotation in a true spin is autorotation - or auto-gyration. It is not aileron induced rolling! So leaving the ailerons out avoids the temptation to confuse the two! Once the aircraft is spinning you are allowed to use the ailerons to control the spin - its just that you shouldn't use them as a way of entering the spin. It makes it too easy for the pilot on the one hand and difficult for the examiner to distinguish if there was a true stall on the other! Note also that you can exit the spin in more or less any manner you like - as long as you are basically aligned with the direction of entry once the spin stops BEB Edited By Biggles' Elder Brother - Moderator on 07/02/2013 09:45:53 Quote Link to comment Share on other sites More sharing options...
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