Geoff Gardiner Posted April 9, 2020 Share Posted April 9, 2020 I am just starting my build of Tony's 50 inch Hawk. I have been collecting parts since the plan was featured in the magazine. Thanks to Mark Elen, for selling me some of his unwanted bits, I have a choice of an 8s power setup or a 10s version. We will see how the weight goes before deciding. First job is to trace all the parts from the plan in Inkscape and then begin cutting with the dremel for the ply bits and laser for the balsa bits. More later... Quote Link to comment Share on other sites More sharing options...
Mark Elen Posted April 10, 2020 Share Posted April 10, 2020 Hi Geoff, I’m looking forward to watching this progress. Cheers Mark Quote Link to comment Share on other sites More sharing options...
Martin McIntosh Posted April 10, 2020 Share Posted April 10, 2020 Get rid of as much ply as you possibly can at this stage. Many parts can have lightening holes made or dispensed with altogether and substituted with something lighter. I speak from experience! Good luck with it. Quote Link to comment Share on other sites More sharing options...
Geoff Gardiner Posted April 11, 2020 Author Share Posted April 11, 2020 Martin, Drat..... Just spent the day gluing on the ply doublers to the fuselage sides. More later... Quote Link to comment Share on other sites More sharing options...
Geoff Gardiner Posted April 11, 2020 Author Share Posted April 11, 2020 It's lovely weather for building out in the garden at the moment. Bit more done today. I have made the aperture in F3 a bit wider so as to fit two 5s Graphene batteries in, if I go down that route. This means the battery tray is a bit wider but I have added some holes to take out a bit of weight. More later... Quote Link to comment Share on other sites More sharing options...
Craig Horsley Posted April 13, 2020 Share Posted April 13, 2020 I just subscribed to this website just for the purposes of following this thread, been considering this build myself but heard mixed reviews about the flying characteristics so looking forward to hearing your results. Quote Link to comment Share on other sites More sharing options...
Geoff Gardiner Posted April 14, 2020 Author Share Posted April 14, 2020 Hi Craig, Welcome aboard. I fly off a grass strip and may have problems with the small scale wheels - but couldn't resist building one! Quote Link to comment Share on other sites More sharing options...
Ray Wood 4 Posted April 14, 2020 Share Posted April 14, 2020 Hi Geoff, I'm also watching with interest, I have all the bits for Tony's smaller version of the Hawk 😀 Regards Ray Quote Link to comment Share on other sites More sharing options...
Piers Bowlan Posted April 15, 2020 Share Posted April 15, 2020 I was sorely tempted to build one of these when the plan was published in the 2017 Autumn Special. I have a 90mm Lander fan for 6s so I thought by eliminating all the liteply/ply, adding lots of holes and doing away with the landing gear it might actually fly (after launching it with a catapult). I think weight is the No.1 enemy with this model as Tony's prototype on 8s had a wing loading of 43oz/squ/in. which, for a dyed in the wool gilder guilder like me is scary territory! Something I did consider was using a semi-symmetrical aerofoil section which might provide more lift at a slower speed. Another deviation from the plan I thought of, was enlarging the intake area and belly cheater hole to help the fan to 'breathe'. I might well build one at some stage in the future as it is an impressive model but in the meantime I will be following this thread with interest - and taking notes! Quote Link to comment Share on other sites More sharing options...
Martin McIntosh Posted April 15, 2020 Share Posted April 15, 2020 Hi Piers, You have probably seen my blog on my 54" version which I built not knowing that TN was in the process of doing a 50" one. Even with a 12 blade 10s fan there was very little thrust but I had omitted the cheat hole, now done at 3x4" but when testing, a connector got sucked into the fan and blew it up. Awaiting a replacement impeller which I hope will fit. As advised above, shed as much ply and other weighty parts as possible. My YEP 120A esc and Rx etc are unavoidably blocking the airflow quite a bit but since it is the same as TN does it is obviously OK. Quote Link to comment Share on other sites More sharing options...
Piers Bowlan Posted April 18, 2020 Share Posted April 18, 2020 Yes, your blog on the 54in version is very interesting Martin. Probably a silly question but I assume you calibrated your ESC to ensure it was giving you 100% power? I am sure that once you get your new impeller the new cheater hole will make a huge difference to the thrust you are getting with your 10s setup. The 7.5% increase in model size will help with the wing loading too hopefully. Just a suggestion but as the model has flaps you, (Geoff and Martin) could try 5 or 10 degrees flap (max) for take off and also droop the ailerons as well for that matter (if your Tx will do that). The added camber and extra low speed lift can only help, with a minimal drag penalty. just my 2p worth! Edited By Piers Bowlan on 18/04/2020 08:05:02 Quote Link to comment Share on other sites More sharing options...
Martin McIntosh Posted April 18, 2020 Share Posted April 18, 2020 Hi Piers, glad you enjoyed the build blog. I certainly am getting 100% power because the esc is programmed for an EDF and the Wattmeter confirms this. I think that the main question will be the small wheels on grass rather than lack of lift. Unless previously tested in the air there is really no way of knowing if flaps make a pitch change. I just hope that the fan I have ordered fits OK since it is supposedly a different make but looks the same in the HK pics. I would buy a new unit but cannot get 10s so my 2x 5800 5s packs would be of no use. Quote Link to comment Share on other sites More sharing options...
Piers Bowlan Posted April 18, 2020 Share Posted April 18, 2020 I agree Martin small wheels on grass produce a lot of drag unfortunately but my thinking here with the flaps is that the wing will produce lift while it is accelerating. This will unload some weight which may help the model further accelerate to rotation speed (which will be lower due to the flaps). It works with full sized aircraft but it is only a theory as far as models are concerned! I am only talking about five/ten degrees of flap, so there shouldn't be any significant trim change. It will be an experimental model on the maiden flight anyway My apologies to Geoff for taking over his blog. I am suffering from CNC cutter envy! Edited By Piers Bowlan on 18/04/2020 13:01:52 Quote Link to comment Share on other sites More sharing options...
Geoff Gardiner Posted April 18, 2020 Author Share Posted April 18, 2020 No problem Piers, it's all interesting stuff Quote Link to comment Share on other sites More sharing options...
Geoff Gardiner Posted April 18, 2020 Author Share Posted April 18, 2020 I wanted to sort out the elevator servo mountings before gluing the fuselage sides together as I don't like servos on show. A little work with CAD and my 3d printer and I have come up with this: More later... Quote Link to comment Share on other sites More sharing options...
Geoff Gardiner Posted April 19, 2020 Author Share Posted April 19, 2020 Fuselage sides going together today. More later... Quote Link to comment Share on other sites More sharing options...
Geoff Gardiner Posted April 20, 2020 Author Share Posted April 20, 2020 I am just cutting the beech fan supports and the build instructions suggest pre drilling the mounting holes before gluing them in. What is the collective wisdom on the type of fixings - screws or nut and bolt? If using bolts, access to the underside will be tricky. Quote Link to comment Share on other sites More sharing options...
Mark Elen Posted April 20, 2020 Share Posted April 20, 2020 Hi Geoff, I had planned to use the no4 cap head wood screws from Modelfixings. Although, I did also consider using 3mm cap screws and T nuts - not sure if they would work in beech. You could make up a tin plate with nuts soldered on and screw it to the underside. The cap heads would be easier. Cheers Mark Quote Link to comment Share on other sites More sharing options...
Martin McIntosh Posted April 20, 2020 Share Posted April 20, 2020 T nuts and socket cap screws is the way I did it. Good job now that I have had to remove the fan. Beech is a bit OTT, ply or spruce is fine. Edited By Martin McIntosh on 20/04/2020 22:31:08 Quote Link to comment Share on other sites More sharing options...
Geoff Gardiner Posted April 21, 2020 Author Share Posted April 21, 2020 Thanks chaps, something to ponder! Bit more done on the fuselage: In an effort to help with weight I made some holes in the motor former Glued in the battery tray Glued in the front and back formers More later... Quote Link to comment Share on other sites More sharing options...
Martin McIntosh Posted April 21, 2020 Share Posted April 21, 2020 I found that hollowing out the top deck in order to fit the tail took quite a while, so it may be worth considering this before fitting it. Quote Link to comment Share on other sites More sharing options...
Geoff Gardiner Posted April 24, 2020 Author Share Posted April 24, 2020 Bit more done today. More later... Quote Link to comment Share on other sites More sharing options...
Geoff Gardiner Posted April 26, 2020 Author Share Posted April 26, 2020 Todays efforts, between jobs in the garden. With the sheeting I glue the bottom edge with cyano, then wet and steam the outer face, use aliphatic on the formers and cyano the top edge. More later... Quote Link to comment Share on other sites More sharing options...
Geoff Gardiner Posted April 27, 2020 Author Share Posted April 27, 2020 Todays progress: Attacked the upper fuselage with a Davids Plane and sanding blocks. I wasn't happy with the amount of balsa on the top inside so attacked that with the dremel. More later... Quote Link to comment Share on other sites More sharing options...
Geoff Gardiner Posted April 28, 2020 Author Share Posted April 28, 2020 Not much to show for load of faffing today. I managed to break the part that the clevis connects to on the retract, so had to design and print a replacement part. Also printed a bracket to stabilise the pushrod. More later... Quote Link to comment Share on other sites More sharing options...
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