Colin Naylar Posted April 8, 2011 Share Posted April 8, 2011 Has anyone started building the Jitterbug? I built the wings first and then started the fuselage by cutting out one of the 3/32" sides. At that point I thought it a good idea to check the fit of the wing in it's cutout. Strangely the cutout is 10" and the wing chord is 10.5". I checked the plan and it is the same. Now the question is 1) do I extend the wing cutout backwards? 2) How does this issue affect the wing incidence 3) An alternative is to cut a gap in the centre of the wings trailing edge. Any comments gratefully recieved. I have emailed Alex but his model was'nt built from the plan but he will get back to me - just thought that if I'm right, then anyone who is building should be aware of this! Quote Link to comment Share on other sites More sharing options...
Colin Naylar Posted April 8, 2011 Author Share Posted April 8, 2011 I have just noticed that in one of the photos in the mag, the leading edge of the wing is in front of the join where the two pieces of 3/32" are spliced. This may not mean anything but could suggest that the wing needs to be moved forward on the plan?. Quote Link to comment Share on other sites More sharing options...
Colin Naylar Posted April 8, 2011 Author Share Posted April 8, 2011 This was a popular free plan then! Quote Link to comment Share on other sites More sharing options...
Pat (rActive) Harbord Posted April 8, 2011 Share Posted April 8, 2011 he he, looks like it's just you then Colin. Anomoly is a big word though Quote Link to comment Share on other sites More sharing options...
IanN Posted April 8, 2011 Share Posted April 8, 2011 Colin looks to be spot on. WIng seat 10", wing chord 10.5". And just to make things more interesting the wing cross section (drawn directly under the dihedral braces on the plan) is 10 and 3/8" Cutting some of the wing TE away at the junction with the fus would make it fit, but then the bands would be pulling the unsupported TE stock upwards. Not perfect, but the timber looks sturdy enough to take it. You could also, as suggested, shift one (or both) of F2 and/or F3. I doubt either would significantly upset the handling Quote Link to comment Share on other sites More sharing options...
Colin Naylar Posted April 9, 2011 Author Share Posted April 9, 2011 ....and now after lovingly crafting the Former F2 from the plan, I find that it is too short to fit the fuselage (by about a centimetre). I am beginning to wonder how much more is wrong with this plan!!! Quote Link to comment Share on other sites More sharing options...
Hugo Fasster Posted April 10, 2011 Share Posted April 10, 2011 there were two different version of the plane in the article, look closely to where the wing band dowel is located. mayby Alex forgot to finalise the plan. he has been a busy man! Quote Link to comment Share on other sites More sharing options...
BalsaBasher Posted April 11, 2011 Share Posted April 11, 2011 Maybe you are being persuaded to purchase a cnc wood pack ???? Quote Link to comment Share on other sites More sharing options...
Colin Naylar Posted April 11, 2011 Author Share Posted April 11, 2011 Its a valid point Balsabasher but I imagine that the plan is still the same and probably would not correspond to the cnc parts Quote Link to comment Share on other sites More sharing options...
BB Posted April 11, 2011 Share Posted April 11, 2011 You could ask the man himself Colin Alex Whittaker - Jiggterbug Quote Link to comment Share on other sites More sharing options...
Colin Naylar Posted April 11, 2011 Author Share Posted April 11, 2011 I am in contact with Alex and he is working on a solution BB Quote Link to comment Share on other sites More sharing options...
Alex Whittaker Posted April 13, 2011 Share Posted April 13, 2011 JITTERBUG WORKAROUND Thanks to Colin for the heads-up. I drew my original plan on lining paper, directly around each part in biro as I made it. So, I know it was within a biro's bollock from being identical to the prototype. That went off to the magazine never to be seen again. I've checked the trial CAD pdf plan I was sent afterwards for checking, and now had it printed out on A3. There were indeed NO discrepancies at that stage. At that point the wing chord and the fuselage aperture matched. Therefore the discrepancy arrived later, perhaps in scaling each side of the plan for print. I apportion no blame. After Colin emailed me, I spoke to SLEC the CNC pack makers, who suggested notching the TE by 1/4". On reflection, this seems a sensible proposal. It’s safe, it involves minimal hassle for builders, it preserves the cg, maintains the wing area (even adds a little), and leaves the fuselage structure untouched. This would be my recommended workaround. By the way, I have no commercial connection with the sale of Jitterbug plans or CNC packs. I was paid for my original article and free plan.I do not receive royalties or payments for the CAD plans or SLEC CNC packs sold by myhobbystores. My main interest is in seeing builders satisfied, and more Jitterbugs in the air. It’s a nice model.On a separate matter, there is only one Jitterbug prototype. It is the same model in all the static and flying shots. Just bear in mind the North Wales weather. The magazine photos were shot over a number of weeks, with the prototype flown by two separate test pilots. This was to get a dispassionate assessment of the model, and also so I could take the flying pictures. There were radio problems with some dodgy brand new servos, and a rough landing, so I had to repair the tail. I decided to remove one wing dowel as a trial, since I found I was tending to use the rear undercarriage dowels anyway. I innocently re-covered the tail with yellow film, since I had run out of checks. I was blissfully unaware that such routine running repairs to a sports model would provoke so many conspiracy theorists. Amusing, though. Even Elvis down our chippy had a good laugh. Quote Link to comment Share on other sites More sharing options...
kc Posted April 13, 2011 Share Posted April 13, 2011 This is always happening! The designer says it was OK when it left him but the plan turns out to be incorrect when bought. Why doesn't RCME send an advance copy of the actual printed plan out to some experienced builder to check and build from? I usually check out the plans I buy and find errors in about 5 minutes! Just needs a ruler.....the errors are invariably similar and of large amounts either exactly 5mm, 10mm or 1/4 inch, 1/2 inch etc. We deserve accurate plans for our money. Quote Link to comment Share on other sites More sharing options...
IanN Posted April 15, 2011 Share Posted April 15, 2011 Posted by kc on 13/04/2011 19:02:14: Why doesn't RCME send an advance copy of the actual printed plan out to some experienced builder to check and build from? I usually check out the plans I buy and find errors in about 5 minutes! Just needs a ruler...... Its hard to disagree with that. It surely wouldn't be difficult to draw up a list of basic checks to be done on the final printed version of the free plan before going ahead and issuing it. I guess publishing deadlines get in the way. The upside is that the free plans are brilliant value. I doubt I'll ever get the time to build more than a small proportion of the ones I'd like to, from the large number I've amassed over the years Quote Link to comment Share on other sites More sharing options...
Myron Beaumont Posted July 22, 2011 Share Posted July 22, 2011 Having just started my version of Jitterbug ,I would point out that Alex's recommendation of a 1/4" cut out of the wing trailing edge should be 1/2" according to the fuselage side elevation so that is wrong as well !. I shall move F3 to a position to the rear of D2 thus providing the extra 1/2" inch in the fuselage sides for the wing chord as drawn.The rear dowel for wing retention and its reinforcement ply piece will be moved rearwards by the same amount .(unless I decide to use the normal bolt on/ front dowels type fixing ) I shall also use a much smaller X-section LE ('cos I don't have anything that size in my stock box mainly).Just checking out the rest of the plan --in case ? I have two engines doing nothing at the moment .A brand new ASP 61 Fstroker & a Super Tigre 42 2 stroker . Any recommendations as to which to fit ? I could also fit an SC 52 Fs or 2 st if I rob them from other aircraft .Which would be best ? It'll be used to teach 'er indoors to fly mostly Any advice most welcome. Myron PS --Just noticed I'll have to glue 3/32" sheet to my particular stock TE wood to get the section as shown . Edited By Myron Beaumont on 22/07/2011 14:40:24 Quote Link to comment Share on other sites More sharing options...
Colin Naylar Posted July 22, 2011 Author Share Posted July 22, 2011 You may not like this Myron but mine is flying on batteries - details on my recent thread 'My Jitterbug flies superbly'. At least I have discovered someone else who is building one!Look forward to hearing moreColin Quote Link to comment Share on other sites More sharing options...
Myron Beaumont Posted July 22, 2011 Share Posted July 22, 2011 Hi Colin Will certainly keep you in touch .Have you found anything that you would have changed in hindsight whilst I'm at the first building stage .(I'll be using standard Futaba S3001s all round ). eg thicker tail feathers perhaps --1/4"? Quote Link to comment Share on other sites More sharing options...
Colin Naylar Posted July 22, 2011 Author Share Posted July 22, 2011 Myron, did you see my earlier post in this thread re F2 being too small. The other thing is all the dowels - the front wing dowel is not of much use and I have used the rear u/c dowel instead as Alex found out. I have since actually screwed the u/c in place (now that I discovered that I could fly it reasonably). I put the elevator servo at the back end. Yes I used 1/4" for the tailplane & rudder too. I had to put about 5oz lead in the nose but that may have been 'cos of the electrics being lighter but it would probably still pay to make an effort to keep the tail end light. Colin Quote Link to comment Share on other sites More sharing options...
Myron Beaumont Posted July 22, 2011 Share Posted July 22, 2011 Colin Yes ,I have noticed that F2 should be 3 15/16 ths ! My elevator servo will be midships with the rest .I noticed straight away that the front wing dowel was in completely the wrong position .If it wasn't for the abutment of the TE to the fuselage ,the wing would move backwards about 1/2" to settle in to a non stressed position . As a retired RR service engineer with a couple of years spent in the drawing office / stress dept /all the manufacturing process shops as an apprentice non-trade engineer ,I shudder to think how they would survive if these errors were present in full size manufacture of aero engines. Myron Quality control normally kicks in at the manufacturing stage. NOT normally needed in the drawing office design dept.Edited By Myron Beaumont on 22/07/2011 16:20:17 Quote Link to comment Share on other sites More sharing options...
Myron Beaumont Posted July 23, 2011 Share Posted July 23, 2011 Colin Have cut out ribs same as the Wot 4 shape . ie:- 18% symmetrical instead of 14.3% symmetrical . Blunter LE too. I have a gut feeling that it will not look a lot like Alex's original.Hope he doesn't mind but I do like the fuselage design ,plenty of room and strong ! Being as you increased the tail feathers to a 1/4 " thickness I feel better about doing the same . I shall also completely cover the wing in 1/16" sheet 'cos I don't really see the point of 2" span of rib capping & I think it will probably weigh the same since I've reduced the skin thickness from 3/32" (I hope) & is bound to be torsionally stronger . Myron. Edited By Myron Beaumont on 23/07/2011 00:41:16Edited By Myron Beaumont on 23/07/2011 00:44:28 Quote Link to comment Share on other sites More sharing options...
Colin Naylar Posted July 23, 2011 Author Share Posted July 23, 2011 Hi MyronWhats your reasoning behind changing the wing section? Is that going to slow it down a bit? You are right about the fuselage shape, especially the front end - room to get your hands in there and easy access to the motor in my case. I did wonder about skinning the wings completely as in the plan there is very little area that is not skinned, I never thought of reducing the thickness - brilliant idea! I couldn't quite see how Alex had finallised the Cabin area. The sliding cover forward of the cabin is a simple and very effective solution (as a battery compartment for me) but it seems to slide under the cabin 'glass'. What I did was fitted a 1/4" dashboard onto the cabin floor and then screwed the front end of the perspex to it. The back end of the sliding cover then fits flush up to the back of the dashboard and the two parts, cabin and sliding cover are completely separate. Quote Link to comment Share on other sites More sharing options...
Myron Beaumont Posted July 23, 2011 Share Posted July 23, 2011 Colin Yes- slightly thicker wing section (about 5 mm ), to slow it down a bit as I've decided to build to accomodate my ASP 61 and I just love my "Ruperts Dad " with a 20% symmetrical wing section and I thought I'd split the difference so to speak . I am moving F1 back a cm to allow for the ASPs weight and end up with the same nose moment arm. It also will allow me to fit my yellow SLEC fuel tank at the acceptably correct height ie :-Middle of the tank level with the needle valve . Not as originally .-much too low IMHO . I'm also using 1 cm square LE balsa on the wing at 45 degrees to flat / horizontal like a diamond if you see what I mean and will wrap the 1/16" sheeting around it and sand to a blunt LE .A bit more weight saved Those very thick ailerons will have lots of holes in as well .Even more weight loss, even with the addition of mass balance weights ! Quote Link to comment Share on other sites More sharing options...
Les Littleton Posted July 24, 2011 Share Posted July 24, 2011 Hi all . Dont forget this is a free plan and a little poetic licence during the build is part of the fun and the challenge of turning a pile of wood into something that looks like a plane and flies like a plane. I did have to recess the trailing edge of the wing but i dont think it will have any effect on the flying . Mine is covered now and i hope to get time to fit it out soon. Quote Link to comment Share on other sites More sharing options...
Mystifried Posted August 5, 2011 Share Posted August 5, 2011 Hello Chaps, I have started the Jitterbug as my first ever build , I cheated a bit and bought the wood packs. I have just come across the F2 / Rear fuel bulkhead too short issue and am scratching my head a little as I am new to all this, but will read all your helpful posts and try and work it out. For some inane reason I decided to start a build log on RCGroups which other members of my club use. I hope no-one will be upset if I include the link. http://www.rcgroups.com/forums/showthread.php?t=1482387 Please feel free comment and appreciate any further tips etc. Mystifried Quote Link to comment Share on other sites More sharing options...
Les Littleton Posted August 9, 2011 Share Posted August 9, 2011 Hi Mystrifried, Ive, had a look at the link and like me you have chosen this as a first build, i hope you have as much fun as i have had.. There is a small problem with the wing not fitting the fus but i recessed the wing trailing edge and it works fine. I used the cnc woodpack and it was all fine. As a first build there were probably a few things i could have done better but it came out the right shape and size and flies well so i,m happy . The message hear is enjoy the build and the satisfaction when it flies makes it worthwhile. I set FI and F2 as the plan and my 8oz tank fitted fine ,and with the asp 61 c of g was no problem . Dont forget to add some pics with your posts . ( beware, this balsa bashing is infectious) cheers, les Quote Link to comment Share on other sites More sharing options...
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