Tony Nijhuis Posted August 30, 2016 Share Posted August 30, 2016 In amongst the day to day churn of the conventional model designing, I have always wanted to design a VTOL Harrier as a personal project as this has to be aeromodelling Holy Grail......so for the last 6-months or so I have been chasing down youtube clips, forums and anywhere else where i can find what the latest ideas are on VTOL....... So having seen countless efforts of single fan versions or quadcopter versions, I really wanted a harrier that would Take off into the hover and then fully transition to normal forward flight, before returning to earth either conventionally of via the hover. Well that all sound quite feasible in my head but as normal, it wasn't going to be as simple as that. So dabbling with quad cop boards, fan units and a mountain of batteries some progress has been made Therefore I thought it was time to share a few photos with you guys. There will be couple of article on this in the RCM&E so more will be revealed in due course General layout...fans are paired in X form quad with two counter rotating. All four fans rotate to provide forward flight. 4x70mm 6S fan units, 4x100amp esc, 2x4500mah 6S 60c cells picture today of Mk1 prototype hovering with final P+I loop tuning done we now have a stable machine. Moving to forward flight shouldn't present to much of a change but power to weight has been the biggest challenge Can gimble the fans to change hovering angle of attack. The Mk3 under way and trying to shave some weight off....If you were wondering about Mk2.....see below Mk2- 70" version AUW 8kg with retracts and using 4x90mm 8S fans.....still have stability problems with this one Quote Link to comment Share on other sites More sharing options...
Biggles' Elder Brother - Moderator Posted August 30, 2016 Share Posted August 30, 2016 Well, er,....WOW! BEB Quote Link to comment Share on other sites More sharing options...
Dave Hopkin Posted August 30, 2016 Share Posted August 30, 2016 Tony have you considered substituting Depron for balsa in some of the low stress areas, might shave a few oz off her Quote Link to comment Share on other sites More sharing options...
Tony Nijhuis Posted August 30, 2016 Author Share Posted August 30, 2016 David, My son has already suggested it but I love balsa wood If all else fails then yes I will. The new fuselage is currently 250g so quite pleased so far Quote Link to comment Share on other sites More sharing options...
Dave Hopkin Posted August 30, 2016 Share Posted August 30, 2016 That love of Balsa shows in every photo and design Tony and I am 3/4 the way through one of your 48" Vulcans Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted August 30, 2016 Share Posted August 30, 2016 Tony Very impressive. I appreciate it is still a prototype but how will you ultimately handle the change from 'holes through the wing' as the EDFs rotate for forward flight? Quote Link to comment Share on other sites More sharing options...
Andy G. Posted August 31, 2016 Share Posted August 31, 2016 Very impressive, watching this thread with interest! Quote Link to comment Share on other sites More sharing options...
Danny Fenton Posted August 31, 2016 Share Posted August 31, 2016 Very impressive Tony, and I look forward to reading about the journey Quote Link to comment Share on other sites More sharing options...
Jon Laughton Posted August 31, 2016 Share Posted August 31, 2016 Yes Wow! And we'll done so far - this is going to be very interesting Quote Link to comment Share on other sites More sharing options...
bert baker Posted August 31, 2016 Share Posted August 31, 2016 Would it be possible to have the speed controlers gyro stabalizzed.,,so it will adjust speeds across the axis,instead of moving in essence a set of aileron servos. Having said that I suppose it is basic quad copter stability anyway Bert Edited By bert baker on 31/08/2016 09:44:43 Edited By bert baker on 31/08/2016 09:46:25 Quote Link to comment Share on other sites More sharing options...
Tony F Posted August 31, 2016 Share Posted August 31, 2016 Hi Tony great subject just a quick question ? When you transition to forward flight how do you get around the front fans directly blowing exhaust into the rear fans ? Will you eventually have angled duct fans ? Be interested to hear how you'll overcome this Tony Quote Link to comment Share on other sites More sharing options...
Denis Watkins Posted August 31, 2016 Share Posted August 31, 2016 As Tony will have found in his research, the full size thrust nozzles on the Harrier are uniquely designed, almost square, and what looks dividers in the path of the airflow, are wing shaped, with internal leading edges producing a layered controlled, less turbulent thrust. Our EDFs are virtually push/pull in operation, making for interesting design solutions. We have to work with the cards we are delt, and when Tony completes this build, I guess it will be one of the all time greats from the TN stable, to be built and flown Edited By Denis Watkins on 31/08/2016 12:14:31 Quote Link to comment Share on other sites More sharing options...
Tony Nijhuis Posted August 31, 2016 Author Share Posted August 31, 2016 Thanks for your kind comments guys..... The holes in the wing are there to provide a direct air path down through the fan during hover I did try the model without these holes and the thing wouldn't even lift off...... When the fans rotate to horizontal mode, the air is drawn through the main Harrier intakes at the front. The fan pivot rotation is timed for three seconds to avoid over torquing the pivot servo and to make a slow transition. Once in forward flight the fans on each side will act in 'series' which means the pressure differential will be double but the thrust is likely to be equivalent of only one fan. The power draw from each fan ( as one is assisting the other) should dramatically reduce....therefore for forward flight loss of overall thrust will suit the lower power requirements of 'forward flight' The biggest hurdle so far is the power to weight for hovering. Fans are at there most inefficient when in static operation and so hovering is absolutely kills the cells....this project could not happen if it wasn't for the high C batteries now available. Quote Link to comment Share on other sites More sharing options...
Allan Bowker Posted August 31, 2016 Share Posted August 31, 2016 Awesome project and fantastic early results by look of things, well done Tony! I would image there are some limitations as to how fast each EDF unit can speed up and slow down to maintain the hover. Looking forward to seeing how this progresses. Quote Link to comment Share on other sites More sharing options...
Tony Nijhuis Posted August 31, 2016 Author Share Posted August 31, 2016 Absolutely correct Allan, the esc on the 70mm fan units have been programmed to high freq but the outcome is still not as effective as a propellor. The loop tuning on the Kk2 quad board has taken a long time to get right but it's not as stable as a quad copter but I don't think it ever will be... The fans are just not as accurate as props would be and the gyros are struggling Quote Link to comment Share on other sites More sharing options...
Josip Vrandecic -Mes Posted August 31, 2016 Share Posted August 31, 2016 From Mr. Nijhuis, Masters of the highest category I did not expect anything less. Modern and classic in one ... electronics and balsa ... Greetings from the Adriatic Sea and all the best Jo Quote Link to comment Share on other sites More sharing options...
Tim Cheal Posted August 31, 2016 Share Posted August 31, 2016 Awesome. I really hope you can get this to work (I am an ex RAF Harrier pilot). I am watching with great interest, please do keep us up to date. Tim Quote Link to comment Share on other sites More sharing options...
Tony Nijhuis Posted August 31, 2016 Author Share Posted August 31, 2016 Thanks Jo....and yes Tim, will keep you all up-dated Quote Link to comment Share on other sites More sharing options...
Former Member Posted August 31, 2016 Share Posted August 31, 2016 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
Tony Nijhuis Posted September 1, 2016 Author Share Posted September 1, 2016 The lighter Mk3 version is almost complete and I'm hoping to have the target finished weight the same as the uncovered Mk1 (shown hovering). The next stage once finished, is to fly the Harrier in conventional form ...i.e. lock the fans i horizontal mode, disconnect the quad board and fly the model off a dolly. This way I can trim the model out for normal flight, noting the trims and throws positions. As the hover trims and forward flight trims will be different, i will have to go back to the old fashioned way of adjusting clevis links to achieve matching trim settings. Once this is done the next big step is transition..... exciting times Quote Link to comment Share on other sites More sharing options...
Martin McIntosh Posted September 1, 2016 Share Posted September 1, 2016 Just signing in to watch this. Good luck Tony. Quote Link to comment Share on other sites More sharing options...
Ian Newton Posted September 2, 2016 Share Posted September 2, 2016 Tony, that looks awesome! I have recently flown both the Ripmax transition VTOL plane and the HobbyKing CL-415 Canadair which are both interesting to fly and really fancy this Harrier when you have got it sorted. Are you using the Hobbyking Graphene batteries in this model? If not, then I highly recommend them as they will supply the power you require for the ducted fan units better than any other LiPo I have used. I use them in my EDF jets and their performance is excellent with hardly any voltage sag throughout the flight, so their power delivery characteristics are just what you will need. They do 'drop off the cliff' at the end though, so make sure you land with time in hand especially as you will need full power to land vertically Quote Link to comment Share on other sites More sharing options...
Cuban8 Posted September 2, 2016 Share Posted September 2, 2016 Those of a certain age will remember Mike Koskela and his Harrier Experiments 20 or 30 years (?) ago. IIRC he managed to get his prototype to hover but never got to transition, given the IC ducted fan technology and electronics available at the time. Wonder what happened to him. I also recall seeing someone building a Harrier fuselage onto conventional helicopter mechanics (inverted) and getting that to fly but it's hardly sporting really. Great effort by TN Edited By Cuban8 on 02/09/2016 13:10:53 Quote Link to comment Share on other sites More sharing options...
Tony Nijhuis Posted September 2, 2016 Author Share Posted September 2, 2016 Thanks Ian, I have been using nanotech 4500mah 45C......but have just ordered a pair of the Graphene 4000mah 65C...hopefully the power delivery and the weight saving (30g per pack) should give the edge. The new Mk3 airframe is 200g lighter so all in Im hoping this weight saving will give additional hovering duration Quote Link to comment Share on other sites More sharing options...
Tony Nijhuis Posted September 2, 2016 Author Share Posted September 2, 2016 Mk3 airframe as it is now...span is 1300mm (52" and length is 1500mm (60" and weighing in 520g (1lb 2oz) so on target to get the model under 3.5kg (7lbs 12oz)...Just ashame we have to carry 3lbs worth of fans and 3lbs worth of batteries.. Quote Link to comment Share on other sites More sharing options...
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