Colin Anderson
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Everything posted by Colin Anderson
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Well done Mowerman. 😊 Mine needed a lot of downtrim, also. I put quite a bit of lead in the nose - 80 g, if I remember!
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Glyn, I used four tiny magnets from Maplin (two each side) for my hatch. These are not too strong, but they do retain the hatch very well. The hatch remains in situ even after a crash, yet can easily be opened with very little effort. Trust me, it works! 😊
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Give them a ring, Glyn. They are very friendly and helpful people; I'm sure they can help you out. 😊
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Posted by monty2 on 16/05/2015 16:32:01 Made up my mind as a beginner for the 2nd time will buy a 2nd trainer while I finish my Jocasta. its taking longer than I expected. I must get back flying for the summer. Winter up here in the North ain't fun I know where you're coming from Monty. I too am a beginner. I built a Piper Cub last year to learn on, but had to move clubs, because I wasn't getting enough instruction. I took my Cub to my new club and had some flights, but something went wrong and it got crashed. It was decided by my club that I'd be better off learning on electric rather than IC and I gained my solo using a borrowed Wot4. As I was only cleared for electric I decided that the Jocasta would be ideal. I finished the build awhile back and was very pleased with it. However, I made 9 successful flights and then mysteriously it became unflyable, crashed and broke a wing. As it broke at the root I was able to repair it and was back in the air after a week. After adding the equivalent of a church roof to the nose it again flew and much better too! Again I made many successful flights, but found landing on our strip difficult; it's not that wide and I was using the entire length to land successfully! Our club site is on a farm so we have plenty of room to fly, but only a short strip to land. Landings therefore have to be fairly precise; not easy for a beginner. The Jocasta is a lovely plane to fly and I find it easy; although in windy conditions I find it quite a handful, especially when it comes to landing. Last week something went wrong and I again crashed, completely destroying the wing! I've now got to make a new one. Obviously, as a beginner, I need to become more proficient with my landings. I'm fine with take offs and confident in my flying, even managing a few stunts. My landings though are sometimes good and sometimes not, often needing several go arounds. So like you I need something else to learn on. Against my nature, but acting on advice from my club today I purchased a foam Wot4.
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Hi Andjo, Yes, in theory I could rebuild the wing, but to be honest it would be easier and more practical to build a new one. I'm toying with the idea of building a new wing without dihedral. I've read recently that aircraft with dihedral, although more stable can be adversely effected by crosswinds. I'm also wondering if using a semi symmetrical aerofoil might make it less "floaty".
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That looks really nice Andjo. I think your finishing method suits Jom's design perfectly. Sadly, I crashed mine today, totally destroying the wing. It was flying beautifully, but during finals it began to drift towards the trees (there was a crosswind); as I tried to bring it back towards the strip it wouldn't respond - I have no idea why. Exactly the same thing happened to me last year; different model, different TX/RX. 😕😳
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Glad to return the favour. I've had much help myself along the way from forum members.
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Glyn, may I ask a daft question? Did you build the two fusalarge halves over the plan? The reason I'm asking is, looking at your image, things don't look right. It appears that you have the uprights inboard of the longerons, whereas they should be between them, as are the diagonals. It also appears that you have a break/joint at the leading edge of the tailplane platform. If you build the two fusalarge halves over the plan, then each half must have an upright at the rear and therefore there will be two making up the sternpost. This is certainly the way I built mine. The screw on holding brackets for the main undercarriage are called saddle clamps. You should be able to obtain them from any decent model shop (although mine seems unable to get them). Page 11 of this post shows my method for steering the tailwheel (it's not the only solution). Note: the long piece of wire extending rearward has not been cut to length in this image. Edited By Colin Anderson on 07/05/2015 10:07:59
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I think Glyn's question is an interesting one. Yes, the free plan is fine for building from, although there were several mistakes of scale on this one. It's interesting that the Jocasta plan was selling for £12 (reduced to £6), yet you can buy the back issue (October 2014) for less! This does suggest that there must be a difference between the free plan and the one you can buy.
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Well, after altering the decalage, by adding positive incidence to the tailplane - which I had to repair anyway - restating the down thrust and adding the equivalent of a church roof (80 grams!) to the nose, I'm happy to report that my Jocasta is now back in the air an flying very well. It now flies pretty much hands off. It still needed some down trim on the elevators as well as right rudder trim, but it no longer stands on its tail when power is applied. Now all I need to do is perfect landing it. In my hands it's still reluctant to come down to earth! Unfortunately a hard landing cracked the undercarriage and broke the propeller. Although the undercarriage was cracked, with a borrowed propeller I was able to get a second flight. I find it better on an 11" x 8" rather than an 11" x 6" (recommended by 4 Max). I never got to make a third flight (probably just as well with a cracked U/C! ) due to a dry solder joint to the ESQ which thankfully showed up before flight!
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Hi BEB, Have just found this thread looking for possible solutions. I've recently built Jim Newbury's Jocasta. If you don't know this plane (why would you) it's a retro style high wing trainer. It's different to what I learnt on (a borrowed Wot 4), but quite easy to fly; at least it was! I made 9 successful flights with it. It had a tendency to climb sharply under power, but at around half throttle it was manageable, although I found it hard to bring to earth. My last landing was a hard one in the cabbages, which bent the undercarriage and tore the mounts off. Following this incident I decided that more down thrust was needed. Having done this and made the repairs it was back to the flying field. Back at the field I made two flights; neither were good, the second being a disaster. On take off the plane climbed almost vertically! And this with the added down thrust. Once up it was pretty near unflyable. It responded poorly to ailerons and our club instructor had to rescue me and brought it in on rudder. On inspection we found I'd reversed the aileron leads! This was promptly rectified and I took it up again. Again an almost vertical climb and again the plain was unresponsive; the flight culminated with a spiral into the ground (which broke the wing). Now down thrust, I believed, should have made the plane fly better. Clearly, it didn't; I've since reset this to what it was. My thought is, was the wing incidence/ decalage wrong to start with? When I placed the wing at the field perhaps I did not seat it correctly and made an unknown fault worse? All the above is a rather long-winded way of asking: would wildly incorrect incidence/decalage have caused these problems? If it's not this then I don't know what to look at. It's got me baffled. I'd like to enjoy flying this plane, rather than crashing it
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Hi Jim, Thanks for this. In total my Jocasta made 9 successful flights before I dropped it into the cabbages. The only damage sustained on this occasion was a bent undercarriage, which also broke the front saddle clamps. Although technically any uncontrolled landing is a crash, this was a very gentle one; I'd cut the power on the approach (I know I shouldn't have) and missed the strip. In my inexperienced hands I felt the model flew pretty well, if different to what I'd got used to (I learnt on a Wot 4). It did have a tendency to climb rapidly under power and our club instructor (who trimmed it out for me) had dialled in a visible amount of down elevator. After repairing the undercarriage and adding (from what you've told me) additional down thrust, I neutralised all the trims - perhaps I shouldn't have! From this point on the model became unflyable; even our club instructor found it difficult. I'm coming to the conclusion that down thrust is not the problem. From my free flight days I remember that once the CG was right the model was trimmed by altering the decalage. Perhaps when I assembled the model at the field the wing might not have seated properly and thus altered the decalage? Perhaps the decalage on my model is not as it should be in the first place? I know there are special tools to check this, but I don't own one. It's going to take me a while to repair the wing (I just can't seem to get the root ribs to mate properly). In the meantime I'm going to return the motor back to its original settings (although I'll probably leave the side thrust in). I'll also need to find a way to check the decalage. I've convinced myself that this is probably at the heart of the problem.
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You are quite correct in saying that my Jocasta only had two bands in the pictures. This was solely for the pictures. I don't fly it that way! When flying I've always crossed the bands. I use eight of them. They are new and tight. A have had a further thought, however. As stated, I originally flew this model with no side or down thrust. Other than a tendency to climb steeply on anything over half power, it flew very well. I found it quite controllable and could even manage a few simple stunts. As a beginner I was quite pleased with it. However, it did clearly need the thrust lines changing. With the down thrust I've put in the prop is quite low on the nose. Before down thrust was put in the prop wash was directly along the fusalarge. However, with down thrust the prop was is effectively directed upwards under the wing. This might be a daft question, but could this prop wash be lifting the wing and cause an excess of lift? Is there such a thing as too much down thrust? And, if so how does this effect the aerodynamics?
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Hi Jim, Yes it's really mystifying. On takeoff the plane climbed almost vertical! Once up even a senior club member had trouble flying it. At present I'm attempting to repair the wing, which broke at the root. However, no matter how hard I try I'm having trouble getting things right. I've put a new root rib in, but I just can't get two halves to seat properly. I know it shouldn't be that hard, as I did it previously when I built the wing the first time. I'm seriously contemplating repairing the wing flat, as it'll be so much easier to get the two wing halves to line up. Regarding side and down thrust. Our club members are of the opinion that the Jocasta needs more. I'm not convinced. Originally I flew the Jocasta with no down or side thrust. It flew well, although it did have a tendency to climb sharply if given too much power. I've since placed 4 washers at the top mounting and two on the left mount. Could you give me advise on how you achieved your thrust lines?
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Well flying my Jocasta today was very much a disaster! After being almost uncontrollable and spinning into the ground, the repairs are going to take me a little while. The tailplane cracked completely across, so I've had to remove it completely, along with the fin, to effect a repair. The wing will require rebuilding of the right hand root; the dihedral brace having completely sheared and the root rib torn out. The fusalarge, undercarriage and motor were unscathed. I'm completely mystified. Last week the plane flew okay, but had a tendency to climb sharply under more than half power. I put in down and side thrust to counteract this and the net result was worse! The plane was climbing even shaper! And here's another mystery. When I got the plane home I noticed that both ailerons were pointing down in the position of flaps. Had I accidentally flipped the flap switch? To answer this I moved said switch and both ailerons moved further down. In other words, they acted as flaps! I flipped the switch back (which should have zeroed the ailerons) but, although both surfaces moved back, they didn't return to neutral. I checked the trim and sub trim, both were showing as being in the neutral position, but clearly the control surfaces were not! This has now got me wondering. Did both ailerons end up in the down position as a result of the crash? If so, it's strange that they would both be deflected down by exactly the same amount. Is it credible that both ailerons could have moved into this position in the air and, if so, how and why? The servos are new. What are the chances of both being faulty? How do you test a servo? I had to wind out the aileron clevises a considerable amount to recentre the control surfaces, which makes no sense! If, by some strange quirk, both ailerons had moved down, might this account for the plane climbing so sharply? Or perhaps I'm just clutching at straws? 😳
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On my third flight yesterday I made an error (I'm a beginner) and stuffed my Jicasta into the cabbages ! Result? One bent undercarriage that sheared off the front saddle clamps. Although there was no damage to the airframe whatsoever, if had to do some surgery on the nose as I now realise that I need some down and side thrust (I'd wrongly assumed that this was built in. As I've no idea how to get the required 3 degrees (?) I've placed 4 thin washers behind the top mounting and 2 behind the left. I'm hoping that this is about right. I was noticing that the plane was climbing sharply (rather than just rising) at anything more than half power and it was possible to prop hang just by putting the power on! I know that aircraft rise and sink depending on motor speed; but vertically? Hopefully I'll be airborne again before the weekend. Although this is a different experience, flying wise, than what I learnt on (a borrowed Wot4) it's a please to fly. And, as I've found out, pretty tough and forgiving in inexperienced hands. 😊
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Honestly can't remember how much wood I used (I already had some), but I would recommend buying all your wood as sheets. If you can get your wood in 4' x4" size it's more economical. All the strip wood that you'll need can be cut from the sheets with a Slec balsa stripper; this will mean that your strips will be more uniform (cut from the same sheet) and also cheaper. 😊
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Just before my first flight with the Jocasta.
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😊 Finally the sun came out and the wind died down to a gentle and hardly noticeable breeze. As I already had everything charged up and ready to go I set of for our flying field. I'd hoped to find myself up there alone, to save embarrassment. However, I needn't have worried. When I arrived two of the members were already present and, as one of them was the guy who had taught me to fly I got him to maiden my Jocasta, as well as trim it out for me. It completed its maiden successfully and landed in one piece; and you're right Jim, it does have to be flown in. As I hadn't flown since November (I'm still a novice) the other member let me fly his Wot4. Following this I took my Jocasta up myself. It's a different flying experience to what I'm used to and I found that using rudder, as well as ailerons much improved the turns. But oh dear, I couldn't seem to land it! Thankfully our club instructor brought it down for me. After that I was on my own. I made a further four flights and did, after several go arounds, manage to land it myself. From what I'm used to with a borrowed Wot4 the Jocasta comes in a lot faster than I'm used to and uses up most of the strip! Well it does in my hands! As I gained confidence I did some loops and found that it will practically loop around its own tail. I tried some very slow, lazy loops and in these the Jocasta rolls of the top. I couldn't get it to roll at all. Lastly I took it up high and tried an outside loop, rolling out at the bottom (deliberately); this went very well. It might be questioned that these manouvers were a little premature for a novice; but I believe in having some fun and it also taught me what the Jocasta is capable of and what it isn't. All in all a good days flying, as the Jocasta made 6 successful flights. Thanks Jim. 😊
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Mine balances exactly where it should with no added weight. It has a 4!max purple power 3s 3300 lipo up front.
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Looks really nice Robert. Good luck with the maiden flight. I think you'll be up in the air before me. 😊
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Finally, she's finished. I'm just waiting for the batteries to arrive and then I can take her up for her maiden.
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