Simon Chaddock Posted October 9, 2014 Author Share Posted October 9, 2014 A start on the tailplane - compared to the fuselage it is tiny! Built like the fin with its 1mm balsa spar flanges flush with the wing surface. The Q400 has a distinct 'upside down' wing section tailplane. It even looks to be an under cambered! so the tailplane is being built using a conventional Eppler section but will simply be installed upside down!. The elevator servo will hopefully be completely hidden in the big root fairing. Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted October 11, 2014 Author Share Posted October 11, 2014 Its only resting on the top of the fin but it does give an idea of how small the tailplane is compared to the fuselage. The wings and of course the ailerons are relatively just as small. Although it should have plenty of thrust to climb away easily from a hand launch but with exactly how much control is anybodies guess. Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted October 15, 2014 Author Share Posted October 15, 2014 Slow progress at the moment as house decorating has taken priority. The elevators added with a joining tube and the servo installed and tested. This is the underside .The horns will be completely hidden within the prominent tailplane/fin fairing. To reach the radio in the wing the servo extension lead needs to be over 1000mm long. Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted October 18, 2014 Author Share Posted October 18, 2014 A bit further -,the rudder servo installed. And the front half of the fin/tailplane fairing. Fiddly to fit as it has to be carefully cut to fit both the fin and the tailplane at the same time. The longer rear half will probably be even worse. The next big task is to design and build the wing or rather its centre section as with the engine nacelles the wing will comprise nearly 75% of the planes weight. No problem when flying but any landing shocks will create a substantial downwards bending moment on it. Edited By Simon Chaddock on 18/10/2014 00:43:50 Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted October 19, 2014 Author Share Posted October 19, 2014 The fin/tailplane fairing complete. The rear part had to be made in two halves.It completely hides the horns and linkage. A side view shows the inverted wing section of the tailplane. The rudder is next. It will be centre pin hinged top and bottom. Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted October 20, 2014 Author Share Posted October 20, 2014 The elevator and rudder under test using a servo tester. I prefer to test them together just in case there is some sort of conflict. Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted October 21, 2014 Author Share Posted October 21, 2014 This is where I really start to worry about the all up weight. The wing plan! The wing span is quite a bit less than the length of the fuselage and its chord even at the root is no more than its diameter! At the moment it looks like it will weigh no more than 30oz (850g) so even with that 'skinny' wing the loading will be relatively modest at 14oz/sqft. I could use scale area increasing flaps but it would require 4 more servos to do and add quite a bit of weight and complexity a penalty which I fear would negate any benefits. Edited By Simon Chaddock on 21/10/2014 15:30:33 Edited By Simon Chaddock on 21/10/2014 15:31:16 Quote Link to comment Share on other sites More sharing options...
Simon Hall 2 Posted October 21, 2014 Share Posted October 21, 2014 This is brilliant and I am watching as others are with great interest. I love these planes and have flown as a passenger on them several times. They are the main lifeblood of my local Newquay Cornwall airport. I like the purple colour scheme best! Quote Link to comment Share on other sites More sharing options...
Martian Posted October 21, 2014 Share Posted October 21, 2014 Simon I'm following your build with great interest as always Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted October 28, 2014 Author Share Posted October 28, 2014 A start on the centre section. It has to be of relatively massive construction as it carried the engine nacelles each of which with its batteries will weigh as much as the complete fuselage. So a big full depth balsa/Depron/balsa box spar. 3mm hard balsa top & bottom flange with 6 mm Depron shear webs. The box has 3mm Depron diaphragms placed along its length for internal support. The complete box is rigid enough to simply build the leading and trailing parts of the wing directly off its front and rear surfaces. The ribs and wing skins are 3mm Depron. The balsa flanges of the box spar are thick enough to be sanded to generate a smooth wing profile. The rear top skin is left off to give access to install the radio which will be built into the wing centre section. In this way only 'servo' wires from the radio have to be contained within the wing structure itself. Quote Link to comment Share on other sites More sharing options...
Colin Leighfield Posted October 28, 2014 Share Posted October 28, 2014 Looking very good Simon. You might be on to something with this one, I'll be surprised if it doesn't fly very well. Might need a bit of care with the cg though. Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted October 29, 2014 Author Share Posted October 29, 2014 The outer panels are tapered 2:1 in chord and over 3:1 in depth (the wing section is much thinner at the tip) The rib master pattern cut out to allow for the 2mm Depron skin. The outer panels only carry aerodynamic loads so can be of a lighter construction using a simple "I" beam but as before with the flanges flush with the wing surface. The lower skin is 'hand formed' to approximately the correct profile and placed over leading and trailing supports strips to match the lower wing section. The ribs and the individual shear web are simply glued in, starting at the root. A process best not hurried. One advantage of POR is it is sticky enough to hold things in place but remains flexible for long enough to allow plenty of 'eyeball' adjustment to make sure things remain straight and true. The aileron servo in place. The wing is just thick enough at this point to completely bury the servo. The wing is then left weighted down on the supports for 12 hours for the glue to harden. The top skin then goes on in one piece and a 6mm Depron leading edge completes the outer wing panel. The full size ailerons are tiny so although mine are scale in span I have increased the chord by 20%. They are top tape hinged and the servo horns are set to give significant 'mechanical' differential. This means that the full 50% of servo travel only has to move the 'down' aileron through a small angle and thus has about 5 times the mechanical advantage. Despite its low torque the 'down' servo is very unlikely to 'stall' against even extreme aerodynamic loads. Edited By Simon Chaddock on 29/10/2014 11:30:00 Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted October 30, 2014 Author Share Posted October 30, 2014 With both outer panels added and just balanced on top of the fuselage it does give an idea of just how relatively small the wing is. At 61" it would not look out of place on a small glider! Even though it may be light I don't think it will exactly be a 'floater' It looks like it will weigh about 28oz (800g) all up. Quote Link to comment Share on other sites More sharing options...
Colin Leighfield Posted October 30, 2014 Share Posted October 30, 2014 Can't see you going wrong now Simon, I like the wing section. Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted October 30, 2014 Author Share Posted October 30, 2014 Colin At 18% at the root it is remarkably thick for what is a 400mph plane but then I suppose it has to support two huge turbo props as well. It is actually very similar to that of a modern glider 'low drag' section with its maximum thickness well aft and slight under camber towards the trailing edge . The only problem is this type of section doesn't perform anything like the same at small sizes but if I am right it will have more than enough thrust to make up for it! Quote Link to comment Share on other sites More sharing options...
Stephen Jones Posted October 30, 2014 Share Posted October 30, 2014 Hi Simon , But have you factored in, the fact that you can not scale up or down the air in which both the model and full size will be flying in . Following with interest. Love you're builds as always, Steve. Quote Link to comment Share on other sites More sharing options...
Colin Leighfield Posted October 30, 2014 Share Posted October 30, 2014 I think the Typhoon had 18% thickness at the root or something very close to it, 400 mph was no problem for it, it was getting up closer to 500 in a dive when it started to disgrace itself. Can't see the Q400 needing to worry about though! Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted November 3, 2014 Author Share Posted November 3, 2014 Almost a bit of chicken and egg situation now. Without the battery each nacelle is significantly nose heavy. The pen represents the likely airframe CofG. The fuselage and tail on the other hand is significantly tail heavy so they might cancel out but I wont know for sure until the nacelles have been fixed to the wing and the wing mounted on the fuselage. The battery position could be used to make up any adjustment required but it would be much easier to make up the nacelle battery box and hatch before they are fixed in place. Quote Link to comment Share on other sites More sharing options...
Colin Leighfield Posted November 3, 2014 Share Posted November 3, 2014 Simon, could you loosely assemble the plane, make up simulations of the battery weights using lead or something, and tack them externally to the nacelles using plasticene or blue-tack, adjusting their position until the cg is where you want it to be? That should give you the position for the battery boxes inside the nacelles? Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted November 3, 2014 Author Share Posted November 3, 2014 Colin that is more of less what I intend to do. Making up the removable wing to fuselage joint will be much easier without the relatively heavy nacelles fitted. Once the joint is complete the nacelles will have to be fitted and the battery position determined - which hopefully will be within the available space within the nacelle! The tricky part is then cutting open the underside of the nacelles. building the battery boxes and soldering on the connectors with the wing and nacelles assembled all in one piece. A start on the wing mount. The wing will be held down by 4 nylon bolts. Edited By Simon Chaddock on 03/11/2014 18:01:30 Quote Link to comment Share on other sites More sharing options...
Colin Leighfield Posted November 3, 2014 Share Posted November 3, 2014 A step at a time and you get there. This is a great build. Incidentally, following the observations about wing thickness, I looked up the Typhoon and it wasn't 18%, it was 19.5 at the root! Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted November 4, 2014 Author Share Posted November 4, 2014 The thick wing of the Typhoon was recognised as limiting its top speed quite early on. 412 mph at optimum altitude from 2200 hp was not particularly spectacular. The Tempest V wing was 14.5% at the root and with the same Sabre IIB engine achieved 435 mph with the benefit of a rather higher limiting mach number. The wing mount progresses with the front part of the fairing completed. The rear fairing is similar but with a shallower form. Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted November 5, 2014 Author Share Posted November 5, 2014 The wing rear fairing was giving me some trouble. On the pictures of the fuselage it was clearly quite big but with the trailing edge of the wing flush with the top of the fuselage it didn't appear to need to be. Eventually found a rear view that showed why the fairing is so big - the rear of the wing is 'built up' a bit. So next is the dorsal spine. It is hollow to carry the elevator and rudder servo wires. The servo wires can just squeeze under the rear wing fairing and pass into the saddle area. There is plenty of space for them to be plugged into flying leads from the radio yet be completely hidden when the wing is bolted on. At last I think I can now see how everything will fit together but there is still quite a bit of work to do. Edited By Simon Chaddock on 05/11/2014 16:54:11 Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted November 6, 2014 Author Share Posted November 6, 2014 This is a lightweight build and there only limited space inside the wing so it seems sensible to use a lightweight radio - a Lemon DSM2 6ch Featherweight. A bit 'overkill' at just 2.7g but they are also very cheap - just under £10 delivered - for two!! Claimed to be full range. We shall see. Edited By Simon Chaddock on 06/11/2014 19:59:06 Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted November 8, 2014 Author Share Posted November 8, 2014 The wing hold down bolts. Each bolt bears down on an end grain balsa pad glued to the spar shear web. This being the strongest part of the wing as the front and back sections are just Depron structures. The bolts screw into a threaded 2mm Perspex plate buried within the wing saddle. Seems to work well enough. With the flight batteries in each engine nacelle the wing bolts will only have to be removed for transport. . Quote Link to comment Share on other sites More sharing options...
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