Peter Miller Posted December 20, 2016 Share Posted December 20, 2016 I did a model of the Zenith Acro. IT was quite nice I can't rememebery what the shape of the tips were. I could go and drag my 3 views out but not at the moment Quote Link to comment Share on other sites More sharing options...
Colin Leighfield Posted December 20, 2016 Share Posted December 20, 2016 If I remember correctly the "flicked up" wingtip tips that you see on the Islander and many other planes were named after a chap called Kuchemann. The idea is that they control the span-wise airflow that causes a vortex at the wing-tip and both improve lift and reduce drag. The "winglet"extensions that we see on most civil jets now are really an extension of the same idea. I'm not convinced that simply sawing off the tips at an angle would do much in that respect, although it will have a slight dihedral effect I suppose. One reason that I have always liked wash-out on a wing is because it seems to me that apart from the basic idea that it stops the outer sections of the wing from stalling before the inner and thus prevents tip stalling, it must have some effect on the spanwise flow of air originating at the root and moving outwards. It might not be great but it is progressive across the span and must have some benefit for the efficiency of the wing. Edited By Colin Leighfield on 20/12/2016 12:02:09 Quote Link to comment Share on other sites More sharing options...
Steven S Posted December 20, 2016 Share Posted December 20, 2016 I believe that all of Chris Heintz's designs had Hoerner wing tips. I build a full size Zenair CH300 back in the 80's after attending some of his lectures at Oshkosh where he extolled on the virtues of the wing tips. Quote Link to comment Share on other sites More sharing options...
McG 6969 Posted December 20, 2016 Author Share Posted December 20, 2016 Well gentlemen, this build blog starts to look like an aerodynamic encyclopedia now. ... Vortex, Kuchemann, Chris Heintz, Hoerner... Just love it. I was just trying to implement a slight 'variation' to Peter's wing tip design, but now I have the impression of getting immersed a some famous international - well, German mostly - restricted club... Only the Power in the Sky knows so far what could emerge from those pencil lines, but maybe I could give it a name like "Gastonheimer"? Mmhhh, sounds good... By the way Steven. Are you still intended to build a Baron 1914? Hakuna matata Chris BRU - BE / CTR Club Control Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted December 20, 2016 Share Posted December 20, 2016 Colin I don't think washout ever improved the efficiency of a wing. The best example I know of concerns the Slingsby T49 2 seat training glider. The prototype was built with 3 degrees washout. With a relatively tapered wing it exhibited erratic stall and spin recovery characteristics which was considered unacceptable in a trainer. After much testing the only reliable solution found was to increase the washout to 7 degrees and fit a slightly bigger fin. It reduced its maximum L/D from 32:1 to 30. Bizarrely one criticism levelled at the final design was that as a trainer it was hard to teach 'spinning' as it simply refused to do so! Quote Link to comment Share on other sites More sharing options...
Colin Leighfield Posted December 20, 2016 Share Posted December 20, 2016 Simon, I can't agree with you. I'm not suggesting that adding wash-out to any wing automatically improves it at all, but that as part of a fully integrated aerodynamic design, it might. 7 degrees is so extreme that surely there's some other factor, I'm amazed that the glide ratio was only reduced from 1/32 to 1/30! Quote Link to comment Share on other sites More sharing options...
Peter Miller Posted December 20, 2016 Share Posted December 20, 2016 There was one Slingsby that was a real pig to fly. Eventualy they found that it actually had WASHIN. IT was never cured Ref Martin Simmons book Quote Link to comment Share on other sites More sharing options...
Steven S Posted December 20, 2016 Share Posted December 20, 2016 Hi Chris - yes I am planning on building the Baron 1914. I really want to build the Chorus Gull, but before that I am going to build Peter's Werewolf and a Baron. Just not sure in which order yet. A new one has popped onto my list, I really like the Das Ghosten Flugboot in the December magazine. What to do? Edited By Steven Shaw on 20/12/2016 23:26:10 Quote Link to comment Share on other sites More sharing options...
McG 6969 Posted December 21, 2016 Author Share Posted December 21, 2016 Hello to all, It seems that I'm not going to build in some wing components of the Slingsby then. I'll stick to my 'Gastonheimer' wing tip project for now and if it doesn't turn out 'acceptable', I'll simply go back to Peter's plan and try to cut some standard foam tips. The basic drawing is finalized so, I'll be able to build a cutting jig very soon now. @ Steven > It seems that you have a lot of projects on the burner, but fine that you plan a Baron 1914 as well. We could even possibly build it together? ... When the Bella gets 'finished' (?), I'll definitely build a Baron next. Well, in fact a Svenson Vicomte 1915, which was the licensed production kit of the Baron drawings. There is a laser short kit that was 'revived' by a few Belgian friends/modellers from the Svenson plan as the original vintage kit is hard to find or quite expensive as a collector item. But back to the Ballerina build first. Hakuna matata Chris BRU - BE / CTR Vicomte Control Edited By McG 6969 on 21/12/2016 11:43:05 Quote Link to comment Share on other sites More sharing options...
Steven S Posted December 21, 2016 Share Posted December 21, 2016 That may work out Chris, as I'm now getting back to finishing my Woodys Pusher wing. Quote Link to comment Share on other sites More sharing options...
McG 6969 Posted December 21, 2016 Author Share Posted December 21, 2016 That should be great, Steven. Don't rush the Woody Pusher though, I'm really not close to have the Bella finalized... Hakuna matata Chris BRU - BE / CTR Baron Control Quote Link to comment Share on other sites More sharing options...
McG 6969 Posted December 21, 2016 Author Share Posted December 21, 2016 Hi again, With the tip ‘drawing’ ready, it was just a matter of cutting a base plate out of Alupanel, together with a slightly oversized rib template, some hardwood blocks to screw all of it together and a length of dowel at the future tip side. I didn’t want the ‘winglet’ to raise above the maximum thickness of the rib, so some old math allowed me to define an angle of about 18° in relation to the flat bottom of the wing. I made a tilted support block at 16° and another one at 20° to check the result before committing to cutting the foam. It doesn’t look like on the picture but, believe me, the rib is tilted to the right side by 16° in regard to the base plate. I suppose the question could arise why I didn’t just glue the bits in position instead of using screws? Well, it allowed me to check the correct angle in the first place, but also will allow me to screw all the bits to the other side of the base plate and automatically obtain a ‘mirror’-jig for the second wing tip. ‘Two for the price of one’… I hope… Hakuna matata Chris BRU - BE / CTR Jig Control Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted December 22, 2016 Share Posted December 22, 2016 Chris From your jig it is not quite clear what the 'plan' shape of the tip will be. If it is to be an 'Islander' type shape I am guessing the intent is something like this. With a flat underside the actual shape of the top surface in the area of the 'cloud' will be significantly concave. No problem if you are carving it from a block of foam but the detail 'shape' both tips must be identical. You really don't want any difference in their aerodynamic characteristics so far out on the wing but with your attention to detail I am sure you will be able to do it. Quote Link to comment Share on other sites More sharing options...
McG 6969 Posted December 22, 2016 Author Share Posted December 22, 2016 Thank you for your concern and comment, Simon. When I did some basic research about the Islander, I rapidly discovered that there were different types of wingtips, probably depending on the type, serial number or date of production. On the picture here above, the Belgian Survey type has some ‘taper’ shaped tips while on the BN-2 with floats the tip is parallel to the last rib. I decided to opt for the ‘parallel’ one - see also the ‘exploded’ view hereunder - as I thought it would be a better fit to the Ballerina wing shape. You’re totally right about my jig not easily showing the future shape of the tip. I had the same problem about 3D visualization when I was trying to produce the simple plan drawing but also wanting to project it in the Y-axis. The problem of ‘Pencil vs CAD’, I suppose. You can see the outline of the tip at the LE if you follow the curve from the rib LE ending near the dowel screw at the right of the pic. Concerning the final sanding, it will not be that complicated as the bottom & TE of the tip remain flat/straight and for the ‘concavity’ on top, a simple card template running from the rib LE to half of the width of the TE will allow me to duplicate the curve to the second wing tip. Note so sure if this becomes a lot more ‘clear’ now. I think I’ll better carve an ‘example’ tip as soon as I possibly can… Hakuna matata Chris BRU - BE / CTR Concavity Control Quote Link to comment Share on other sites More sharing options...
McG 6969 Posted December 22, 2016 Author Share Posted December 22, 2016 Hi again, As the time is getting closer to use it, I would like to introduce my high-tech wire cutter. Agreed, it looks ‘toy-ish’… and it is even cheaper than that. Even Gaston refused categorically to be present for the picture. It works at 5V from a wall charger at 1500mA… so, it’s really not ‘that’ impressive and will really not ‘take off’ on its own. I also couldn’t find any ‘thick’ blue foam locally so I’ll have to pack up two layers of 30mm foam. And I already have that annoying feeling that the hot wire won’t appreciate the UHU Por… For the sake of testing, I also cut some scrap pieces of Styro packaging to the profile of the Ballerina ribs prior to cover them with some strips of soft foam. Of course, nothing to do with Bella’s wing tips and not even looking very ‘neat’, but these ‘benches’ will be very helpful to support the wing when the time comes for fiber glassing the whole thing… Hakuna matata Chris BRU - BE / CTR Wire Cutter Control Edited By McG 6969 on 22/12/2016 19:31:46 Quote Link to comment Share on other sites More sharing options...
McG 6969 Posted December 23, 2016 Author Share Posted December 23, 2016 Last night when I was posting the wire cutter picture, that orange with that pale blue of the foam reminded me of 'something' but I couldn't find what it was... I must have had some strange dreams about it though as when I woke up this morning, I suddenly knew what it was. The former Gulf Racing colors, of course... Hakuna matata Chris BRU - BE / CTR Gulf Control Quote Link to comment Share on other sites More sharing options...
McG 6969 Posted December 23, 2016 Author Share Posted December 23, 2016 Hello gents, When I stopped having projections of Gulf Racing deco schemes, I went for a try at those ‘Gastonheimer’ wings tips. I had a quick test piece with some insulation foam first to check the scroll saw angle at 16° and then had two pieces of blue one prepared and glued together. I also added a 3mm ply piece to the TE to have 15mm of extra foam that will be trimmed later to correspond exactly with the Balsa TE of the wing. The cutting went smoothly for a first approach to this blue stuff and, in no time, I was looking at the first ‘Gastonheimer’ tip ever… Probably due to the emotion, I even forgot to take a picture before starting with the sanding. Sorry for that. I masked about 10mm at the rib side and gave the tip a first rough sanding. For those interested, I used a foam sanding block for plaster walls. I guess you all know the type with two different grits at each side. To obtain the ‘concavity’ at the top, I tried an old trick from body repair shops which is a small length of straight automotive rubber radiator pipe covered with 150 sanding paper. This works really great. As I feared, the Por is too rubbery to give a smooth sanding, so I intend to carve it away and fill the small gap up before going on. The idea is to finalize the sanding further when the tip is adjusted and glued to the wing. Up to the next one now, I guess. Hakuna matata Chris BRU - BE / CTR Tip Control Quote Link to comment Share on other sites More sharing options...
Rosco Posted December 23, 2016 Share Posted December 23, 2016 No need to say much my friend.....just......Very nice work, as usual!Keep it up. I'm looking forwards to an almost finished wing soon. Belive me, when you can fit the wing up, you'll feel like you've turned a corner in the build because the wing will make the plane look like a plane!RoscoEdited By Rosco on 23/12/2016 20:51:24 Quote Link to comment Share on other sites More sharing options...
Colin Leighfield Posted December 23, 2016 Share Posted December 23, 2016 Excellent Chris. Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted December 24, 2016 Share Posted December 24, 2016 Chris POR's 'rubberyness' is a big drawback when you have glued joints than need to be sanded. It can really make a mess of an otherwise smooth surface. You can always use foam safe super glue. I have also used wood glue (Resin W) which dries hard so sands well but the joint really has to held in place whilst it dries which can take a day or more! Gorilla glue spread very thin works well too but as it expands it most definitely has to held secure. You can even dampen one surface to make it cure faster. Once it has 'gone off' it sands easily and it really sticks! Quote Link to comment Share on other sites More sharing options...
McG 6969 Posted December 24, 2016 Author Share Posted December 24, 2016 Thank you for the kind words, gents. I only had one small bottle of foamsafe CA, but after only one use, it went rock hard in a few weeks. Still don't understand why as it was kept in a glass jar with some Silica bags. Next time I'll follow your advice, Simon. Some wood resin or Gorilla equivalent PU glue. Hakuna matata Chris BRU - BE / CTR Sanding Control Quote Link to comment Share on other sites More sharing options...
Rosco Posted December 24, 2016 Share Posted December 24, 2016 I always thought your sign off phrase "Hakuna matata" was something in your native language Chris but I've since found out what it means!No worries Rosco Quote Link to comment Share on other sites More sharing options...
McG 6969 Posted December 24, 2016 Author Share Posted December 24, 2016 No, Rosco, it isn't French at all as you discovered. 'Hakuna' is the negative form in Swahili, while 'matata' means 'troubles' or 'problems' or as you wrote 'worries'. It is also a song from the cartoon movie 'Lion King'. Chris BRU - BE / CTR Matata Control Quote Link to comment Share on other sites More sharing options...
McG 6969 Posted December 24, 2016 Author Share Posted December 24, 2016 … a bit of shopping left to go for, some gifts to prepare, some diapers for the ‘little boy’ to get handy as well and a small amount of social commitments to fulfil, but I couldn’t wait to share this with all the Bella’s blog visitors… Hakuna matata Chris BRU - BE / CTR Xmas Control Quote Link to comment Share on other sites More sharing options...
Colin Leighfield Posted December 25, 2016 Share Posted December 25, 2016 Merry Christmas to you too Chris! Quote Link to comment Share on other sites More sharing options...
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