Simon Chaddock Posted July 23, 2014 Share Posted July 23, 2014 When selecting an original for a Depron build it seems logical to find some design that to fly well will make best use of its light weight. My Bachem Natter was such with almost no wing at all I have seen one of these fly overhead out of Liverpool and they look like they have 'pencils' for wings! It would look impressive but as a model it would have to be really light to fly (and land) at a reasonable speed. The six bladed props might be a bit of a problem thought. Just an idea. Quote Link to comment Share on other sites More sharing options...
Tony Bennett Posted July 23, 2014 Share Posted July 23, 2014 like that simon. so it will be built and flying by the end of the month then. Quote Link to comment Share on other sites More sharing options...
John Privett Posted July 23, 2014 Share Posted July 23, 2014 I've flown on those a few times (flybe, LGW-NCL) and, whilst the wings aren't big, somehow the 3-view drawing makes tham appear a lot smaller! Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted July 24, 2014 Author Share Posted July 24, 2014 John Were you flying the shorter versions (200/300)? The same wings do not look quite so small on them. Bombardier are proposing an even further stretch (Q400x) to 90 seats. That will be almost Concorde length! Quote Link to comment Share on other sites More sharing options...
John Privett Posted July 24, 2014 Share Posted July 24, 2014 Not sure to be honest! Here's a hastily-grabbed shot of one of them as I disembarked at NCL. Partial reg is G-**EV Quote Link to comment Share on other sites More sharing options...
John Privett Posted July 24, 2014 Share Posted July 24, 2014 Seems this one was G-KKEV and is/was a DHC-8-402, a 78-seater 400-series, though not actually a Q400. Quote Link to comment Share on other sites More sharing options...
Colin Leighfield Posted July 24, 2014 Share Posted July 24, 2014 If you're going into impossibly high aspect ratio spindly wings on humungous fuselages, what about the Short 360/Sherpa? Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted July 25, 2014 Author Share Posted July 25, 2014 John The only difference between the Dash-8-402 and the Q400 is in the electronic sound compensating system hence the 'Q'! Colin The Short Sherpa would certainly make an interesting model but with a wingspan of 74ft (braced) and a length of 58ft its ratio is almost 'modest' when compared to the 91 to 107 of the Q400. I had not realised that the US Army had by far the biggest fleet of Short Sherpa (43) being in service from 1995 to 2014. Quote Link to comment Share on other sites More sharing options...
Colin Leighfield Posted July 25, 2014 Share Posted July 25, 2014 Simon. What intrigues me with these high aspect ratio load carriers is just how it is possible to practically keep them within the cg range. With such a narrow relative chord in relation to the fuselage length, you would think that it would be a nightmare. particularly with something that is clearly meant to be a practical knock-about aerial truck like the 360. The Hurel-Dubois HD series prototypes from the 50s were similar, although the span/length ratio was much higher. Even the Liberator with the Davies wing must have been quite similar in that respect. As a kid in the fifties I was hooked on the US X-planes and read everything I could about them. I was always making chuck gliders and I found that when the wings were very small and combined with a fuselage which had a large relative side area, that they weren't generally stable. It was as if the fuselage lift was over-riding the wing in the turn and caused the plane to yaw. Now I can see that the solution would have been larger tail surfaces but in those days my target was something that looked scale. Imagine a Douglas X3 chuck glider! Now if you are looking for another Depron challenge(!), but for heaven's sake, don't ask me! Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted July 25, 2014 Author Share Posted July 25, 2014 Colin I suspect the answer is that compared to the chord they can probably tolerate a relatively wide CofG range as the tail plane moments tend to be similar to a conventional winged aircraft. With the power and weight of the Sherpa I would imaging if it still had its nose wheel on the ground it could fly! On that note when I flew to the Channel Islands in a Islander they did put a prop under the rear fuselage as you boarded and the steward told each passenger where to sit, noticeably the big ones were close to the CofG! To make matters worse the steward did not even fly! Quote Link to comment Share on other sites More sharing options...
Colin Leighfield Posted July 25, 2014 Share Posted July 25, 2014 Simon, I would imagine that you must be right. Your comment about the Islander compares with the Liberator. They carried a tail end support and the first job of the crew when alighting was to fix that in position. If they didn't, the plane would "tail-sit" when empty. Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted July 29, 2014 Author Share Posted July 29, 2014 A few more thoughts on a Q400 First a 6 blade prop is just too difficult but anything less than 3 would look odd. Even 3 blades are not that common so it looks like the size of the plane might have to be set by the size of the prop. I had in mind to size for an 8" prop but cant find any. The next best is a 9x5 - actually a 'handed' pair. To scale this would give a 64" span. The fuselage would be 74" long and a 6" diam. I have even found a suitable 2" 3 blade spinner. The engine nacelles are so long it would be a pity not to put the LiPo and ESC in behind the motor and it also has convenient 'front to back' cooling apertures. The fuselage will thus be completely empty. I had not intended undercarriage although a simple wire skid under each nacelle might be required to protect the props. I don't yet know yet how much it would weigh but probably insufficient to take the "A"! Edited By Simon Chaddock on 29/07/2014 18:57:22 Quote Link to comment Share on other sites More sharing options...
Rob Lewis Posted July 29, 2014 Share Posted July 29, 2014 Hi Simon, I fly these 'beauties' for a living. Was flying KKEV in the picture above a couple of days ago..... If you need any info or other pictures let me know and i'll see what i can do. Rob Quote Link to comment Share on other sites More sharing options...
John Privett Posted July 29, 2014 Share Posted July 29, 2014 Rob - I don't suppose it was you that flew me to NCL, was it? 25 Oct 2008, departed LGW around 10:45am, arrived NCL noon-ish... Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted July 29, 2014 Author Share Posted July 29, 2014 Rob Thanks for the offer however I am still not completely sure I will build it and I think I can get all the details I need from various pictures but if I get stuck I will let you know! (that's "I" seven times in a sentence!) Quote Link to comment Share on other sites More sharing options...
Rob Lewis Posted July 30, 2014 Share Posted July 30, 2014 Not guilty John , I'm based in Belfast, so 95% of my flights are to / from there. No problem Simon, I've been toying with the idea of building one myself for some time, most likely glow or petrol, but its probably one of those projects that will never get off the ground. Too many other projects filling the void. Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted August 7, 2014 Author Share Posted August 7, 2014 Slowly accumulating the bits as I find them cheap enough! The 9x5 prop on a part of the blown up 3 view so I can check dimensions. The span will be 65.5", length 76" and the fuselage 6.25" in diameter. The 2" spinner will dwarf the 28mm diam of the motor! Edited By Simon Chaddock on 07/08/2014 15:18:01 Quote Link to comment Share on other sites More sharing options...
Capt Kremen Posted August 7, 2014 Share Posted August 7, 2014 I'm in the process of modifying a MPX 'Twinstar' into a way standoff scale 'FlyBe' Q400. T-tail (obviously!), trike u/c with steering and flaps for short field performance. It's been a long term on/off project but not too far off now. As for fullsize 'FlyBe', as a fairly frequent user of this operator, I have often been asked to relocate from my assigned seat forward or aft in the cabin when self-loading cargo i.e. passenger numbers, have been less than full. Perhaps pilot Rob can enlighten us, I assume this is for the trim sheet the loadmaster/despatcher gives you to sign off whilst in the drivers seat(?) Quote Link to comment Share on other sites More sharing options...
Rob Lewis Posted August 8, 2014 Share Posted August 8, 2014 Hi Capt Kremen, You are correct. As with all planes we need the C of G within the correct range (18 - 30% MAC give or take) before we set off for obvious reasons. The Dash by design is nose heavy, so when we carry a smaller number of passengers that is why you see everyone crammed towards the rear of the plane and loads of empty seats up front. Its not helped by the change over recent years to luggage, people use to always check a bag, which with the hold at the rear of the aircraft, would help our trim. Nowadays everyone crams everything into a carry on bag, so we don't have the weight in the hold to balance us out. Re moving passengers, this usually happens because a passenger or 2 haven't turned up which moves the CG forward / aft, so we ask people to move to get it back into the allowable range. Rob Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted August 10, 2014 Author Share Posted August 10, 2014 One of the issues in using a small 3 view as a plan is that by the time it is blown up to the required size it becomes rather pixilated! This is the top view of the wing root at about half the eventual size. Some of the more complicated shapes get quite hard to determine and horror of horrors it is not unknown for the 3 view to actually be quite distorted. The solution is 'expand' the file up to the required size and then spend several hours redrawing it line by line and in some cases pixel by pixel using proper thin lines and removing any detail that is not required. This is small file version of the top view (small enough to be down loaded), the original file is nearly 100 times the size. When printed out at full size it becomes the plan for the wings and tailplane. Now I just have to do the same for the side view to determine the 'shape' of the fin, cockpit, rear fuselage and engine nacelles. Quote Link to comment Share on other sites More sharing options...
Paul Marsh Posted August 10, 2014 Share Posted August 10, 2014 I know that the Q400 can stall nastily and take a while to pull out. One such full size crash was on Air Crash Investigations of Colgan Air. The pilots were fatigued and didn't respond to stall warnings. Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted August 12, 2014 Author Share Posted August 12, 2014 The redrawn front and side views. I have checked some of the major dimension against each of the views and they all match to within a few of pixels. As the left and right side are now 'copy & paste' true mirror images I know they are identical - which could not be said of the 3 view! Now to start thinking how to actually make the fuselage. Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted August 14, 2014 Author Share Posted August 14, 2014 Now I have an accurate full size 3 view it is relatively easy to find the wing area - 2.25sqft As it will have the same motors and battery size as the Cessna O-2 (or the Hamilcar) I can use these to make a reasonable guestimate of the all up weight - 30oz So giving a wing loading of 13.3 oz/sqft. High(ish) by my light weight Depron standards but not too bad. The Wing Cube Loading (WCL) which take size into account comes out at 8.9 which puts it somewhere between the trainer and sport categories. With 240W installed the power loading will be 128W/lb which should be adequate. I don't really know what these sort of calculations actually prove other than it should fly ok! Quote Link to comment Share on other sites More sharing options...
Colin Leighfield Posted August 14, 2014 Share Posted August 14, 2014 I think it's going to be quick. I hope the pilot's prosthetic arm doesn't fall off when he's landing it! ( Did you hear about that this morning Simon)? Quote Link to comment Share on other sites More sharing options...
Chris Bott - Moderator Posted August 14, 2014 Share Posted August 14, 2014 Posted by Colin Leighfield on 14/08/2014 10:46:54: I think it's going to be quick. I hope the pilot's prosthetic arm doesn't fall off when he's landing it! ( Did you hear about that this morning Simon)? You really couldn't make it up, could you Colin? Quote Link to comment Share on other sites More sharing options...
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