Futura57 Posted January 27 Author Share Posted January 27 10 minutes ago, Chris Walby said: Looks to fly well, what's the low/high speed and stall like? Today was a job to keep it in the air. With a strong tendency to roll to the left it was all I could do to straighten her out for the landings. Hence just one circuit each time. The three videos show all of today's flights. Anything else would be running before I can walk. 😉 Once the wing warp is rectified and I can fly her with full control, then I will explore the flight envelope further. Quote Link to comment Share on other sites More sharing options...
Lipo Man Posted January 27 Share Posted January 27 5 hours ago, Futura57 said: Today was the maiden flight of my Strange Quark EDF design. Below are some short videos showing the first three attempts. You be the judge... Maiden Flight.mp4 2.74 MB · 0 downloads Second Flight.mp4 6.44 MB · 0 downloads Third Flight.mp4 6.11 MB · 0 downloads Well that is a fantastic looking thing, and the flight performance seems to have real promise. Interesting! Quote Link to comment Share on other sites More sharing options...
Futura57 Posted January 28 Author Share Posted January 28 11 hours ago, Lipo Man said: Well that is a fantastic looking thing, and the flight performance seems to have real promise. Interesting! Thank you @Lipo Man. It certainly did turn a lot of heads at the field yesterday. Despite the over sized exit nozzle it packed a fair punch. I only kept it in a low circuit because of concern keeping it under full control. As soon as I rectify the warped wing I will start putting her through her paces. I think I will also try a short add-on convergent nozzle, about 50mm long to reduce the exit area to about 90% of FSA, this time calculating correctly 🤔 Perhaps not as good as the entire outlet duct gradually converging, but fun to experiment with nonetheless. 1 Quote Link to comment Share on other sites More sharing options...
Futura57 Posted February 1 Author Share Posted February 1 I had 3 successful flights today after correcting the warped wing. Started with a 3 minute flight then increased next to 4 minutes, then finally 4.5 minutes, which left 25% in the 4S 2200 mAh lipo. I am very pleased the duration matches my Eflight Ultimate 3D on the same lipo. The video below is not great. Why my buddy recorded portrait I do not know. It's edited from the first flight when I still had trim issues. I've concluded the torque of the fan is what's causing her to still bank to the left. Nowhere near as much as before, but very noticeable after first trimming at around half throttle, then the bank kicks in when I open the throttle. I wasn't expecting an EDF model to react quite so much. By the third flight I was much more in control and looping her (straight) from full throttle level flight. Rolls weren't too bad either. Of course non of this is on video. Elevator trim doesn't seem to need changing over much of the speed range. I didn't try to fly too slow today because of concerns over control authority. I feel the control throws need increasing and it wound definitely benefit from larger elevons. No additional convergent nozzle added at this time. I am happy with the performance for the time being. Small steps. 1 Quote Link to comment Share on other sites More sharing options...
Futura57 Posted February 5 Author Share Posted February 5 Not one to rest on my laurels for too long, I’ve decided to think about developing Strange Quark Mk2. I want better performance, which means faster and more manoeuvrable. Longer flight duration would be nice to have. Constraints Similar model size to Mk1 Similar construction materials to Mk1 – Foam, balsa & lite ply 4S lipo power 1,000g target Duration Increase lipo capacity from 2200mAh to closer to 3000mAh Faster (more thrust) Increase EDF from 50mm to 64mm (on order) Shorter thrust tube & reduce exit area to 90% FSA - calculated properly this time Faster (less drag) Reduce size of main intakes Reduce width of nose Thinner but stiffer wings Manoeuvrability Larger control surfaces &/or greater throws. Yaw control for knife edge flight, etc – rudders? Vectored thrust (on order) – for pitch and yaw capers Other suggestions are welcome. Quote Link to comment Share on other sites More sharing options...
Chris Walby Posted February 5 Share Posted February 5 Hi, I think you are looking to gain too much as items on the shopping list contradict themselves, IMHO Constraints Similar model size to Mk1 Similar construction materials to Mk1 – Foam, balsa & lite ply 4S lipo power 1,000g target, bigger/heavier battery, but you want longer flight time? Duration Increase lipo capacity from 2200mAh to closer to 3000mAh Faster (more thrust) Increase EDF from 50mm to 64mm (on order), well that should reduce the duration if it has a higher wing loading due to weight, unless you are reducing drag, but not sure how that works with increased wing loading? Shorter thrust tube & reduce exit area to 90% FSA - calculated properly this time Faster (less drag) Reduce size of main intakes, no knowledge in this department, but will that actually effect drag as it the sucky bit? Reduce width of nose, pointy nose might save a couple of % yes it will help, but not by much? Thinner but stiffer wings, I get the logic so yes it will fly faster, but it will also have a higher stall speed due to the increased wing loading Manoeuvrability Larger control surfaces &/or greater throws. Yaw control for knife edge flight, etc – rudders? Won't this add weight and drag? Vectored thrust (on order) – for pitch and yaw capers, IMO but I found that VT screwed the fan efficiency, added weight and probably adds overall drag How about a SQ 2a and 2b? Thin wing light weight low drag sports model Retain original wing and load it up with rudder servo, VT IMHO by combining everything it will end up porky with a very narrow flight envelope, but what do I know! Quote Link to comment Share on other sites More sharing options...
Futura57 Posted February 6 Author Share Posted February 6 As the late Freddie Mercury once sang; I want it all and I want it now! A longer flight duration would be nice to have. But my excuse is it was a last-minute addition to my wish-list. On reflection 4.5 minutes is actually pretty good for my Mk1 model when I compare it to some of the ARTF foam EDF jets flying at my club. Regarding the matter of upsizing my EDF for SQ Mk2, I ordered this 64mm PowerFun unit from Banggood for a bargain price. At first glance the thrust claim of 1,460g looks impressive (on Banggood) … However, the thrust published on the 4-Max site is 1,072g. Assuming they are one and the same product, then I’m inclined to believe the (lower) 4-Max figure. The same 4-Max page also shows a thrust of 1,086g for my current FMS 4S 50mm V2 unit. So there appears to be nothing between them thrust-wise! Why would I upsize to the PowerFun 64mm unit, which is 75g heavier, for no added thrust! Help, I am confused. Quote Link to comment Share on other sites More sharing options...
Futura57 Posted February 13 Author Share Posted February 13 I received my 64mm EDF and 50A ESC today which will go in my Strange Quark Mk2. I want to make a number of improvements to try to reduce drag and increase manoeuvrability. Thinner, stiffer wings are first on my list, along with larger elevons. Second is reducing the depth and width of the rather bulbus fuselage. I also want to reduce the main intake size in keeping with commercial foam EDF jets. It's very noticeable how the current MK1 model slows down when I throttle back. It needs to be more slippery. Hopefully these changes will also shave off some weight from the airframe to mitigate some of the added weight due to the larger EDF and potentially larger lipo. I've not yet received the vectored thrust unit I ordered, so I'm unsure about using it versus conventional rudders. So... Mk2 begins here. Mk1 : I want to reduce this fuselage frontal area. Quote Link to comment Share on other sites More sharing options...
Futura57 Posted February 14 Author Share Posted February 14 I received my Freewing 60mm vectored thrust unit today = +40g. Ordinarily this would require two small servos to operate it. I may try to operate the yaw by mechanically linking it to the servo for the rudders! Pitch operation will require a separate servo because of elevon servos. Lets say +9g, though a 5g servo may suffice. Weight difference between 50mm FMS EDF V2 and 64mm Powerfun EDF = +74g Started on the front wings. Cut from 10mm XPS foam sheet with 3/32nd hard balsa for; 2 spars 10mm deep, LE 5mm deep & TE 3mm deep. I am very happy with the twist and bending stiffness already and only 38g per wing so far. That's light for me. The area between the spars will stay flat. The foam area between the rear spare and TE will be sanded down to 3mm at the TE. The foam area between the front spare and LE area will be sanded to 5mm round the LE. At first I was going to veneer the wings with 1/16th balsa sheet, but changed my mind because of extra 40g per wing plus the cost. I am going to try paper for the first time. I don't have any brown paper so may try lining paper. Will try a test piece first. What else is there to do on a wet and windy day 🤔 1 Quote Link to comment Share on other sites More sharing options...
Futura57 Posted February 17 Author Share Posted February 17 The front wings are now covered with brown paper, stuck on with slightly diluted Titebond wood adhesive. After a light sanding they were given a sealing coat of Titebond and, once dry, another light sanding. This glue sands really well, much better than PVA. There is a nice surface ready for painting and each wing now weighs in at 50g, which means the brown paper and glue added 12g. I have to say it's been a revelation. I took a wetter approach to applying the brown paper than many advocate. In the end it was like applying thick tissue. I could stretch it over the foam surface and easily tear a rough edge by rubbing my thumb along the balsa leading and trailing edges to remove the excess. I have now assembled the rear wings, sanded them to a nominal aerofoil and cut out some larger elevons. The rear wings have 2 x 10mm sq balsa at the elevon interface, undercut on the elevon to allow downward movement when eventually hinged along its top edge. Brown paper is stuck to the ends of the elevons and the reveals in the wings. When dry I will sand the edges to remove excess paper, then cover the upper and lower surfaces. The wings are ostensibly the same as the Mk1 model as regards their plan outline, but are stiffer and nearly half the weight of the Mk1 wings. They are a tiny bit larger in area due to the chord being increased by the addition of the balsa spars, etc. Front wing chord +12mm, rear wing +28mm. All this work is improvised, so I need to draw the wings full size and record all measurements before I cover them and forget where the hell I put everything. By concentrating on the wings I am effectively procrastinating over a new fuselage design. But that's fine. The cogs are still turning in my head. In the end, if this Mk2 model performs the way I hope it will, then I want to be able to create a plan / build article quickly without building yet another. 1 Quote Link to comment Share on other sites More sharing options...
Futura57 Posted March 13 Author Share Posted March 13 (edited) Some progress with Mk2. The revised fuselage design is coming together with reduced size main intakes compared with Mk1. The underside intake sloping approach to the mid fuselage section will accommodate cheat holes, especially for high-alpha and vectored thrust (VT) tumbling. Front of fuselage is 2cm narrower than Mk1 but still accommodates 4S 2700. I decided to squeeze in a 70mm EDF unit to get significant extra thrust over the 50mm unit in the Mk1. Had to bring it further forward to mitigate a tail heavy outcome. Exit duct is 28cm long (versus 20cm in Mk1) made from double thickness rolled wall lining paper impregnated with slightly diluted Titebond wood adhesive, weighs 30g. My wife's rolling pin came in handy here for fabrication, despite the slight conical shape of the exit tube. I haven't calculated the exit area reduction %, just went with my gut. Who cares. Servos likely to be placed about the front wing with lightweight snakes to the elevons and VT unit. This will necessitate top hatch access, so a bit more fiddly work. ESC will sit in rectangular cut-out in fuselage side under the front wing exposed to airflow in main intake. I also plan to bring the angled fins further forward to reduce 'shielding' from rear wing in high alpha flight. Am still considering dual rudders in conjunction with VT yawing. On the downside, I accidentally sat on Mk1 and broke off the nose 🤬 Duh! NB the plan in the picture is Mk1. Edited March 13 by Futura57 2 Quote Link to comment Share on other sites More sharing options...
Futura57 Posted March 17 Author Share Posted March 17 (edited) Bear in mind I am very much making this up as I go along. I made up two servo trays today. The rear most V-shaped tray holds the 9g metal geared elevon servos. This tray is angled downwards about 30 degrees and incorporates little stand-offs to support the snake outers, which curve under the fan unit and exit the rear fuselage sides above the rear wings. The forward tray holds two 17g metal servos for the vectored thrust (VT) pitch and yaw controls. Two snakes will be used for dual rudders with linkages to the VT unit. I may 'close-the-loop' by linking the two rudders also, to be decided. A single snake will be used for VT pitch control. Keeping the servos forward is necessary to mitigate the heavier fan unit, exit tube and VT unit. The 60A ESC is under the right-hand-side of the front servo tray and pokes through a rectangular opening in the side fuselage, and is flush so it is caressed by the main intake airstream. The ESC cables (just visible) should only require short extensions, though their final route is to be decided. Edited March 17 by Futura57 Quote Link to comment Share on other sites More sharing options...
Futura57 Posted March 22 Author Share Posted March 22 A little progress today. Made twin fins and rudders from 6mm XPS foam edged with balsa and covered with brown paper. Wider balsa rudder posts will take a double sided horn. Inner horn will join to servo/snake link while outer horn will link to VT unit yaw control. At least, that's the plan. Quote Link to comment Share on other sites More sharing options...
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