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Harrier Jump Jet- The aeromodelling Holy Grail !!!!

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Tony Nijhuis30/08/2016 22:28:17
609 forum posts
233 photos

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 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 madethumbs up

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 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.

img_4468.jpg 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

Biggles' Elder Brother - Moderator30/08/2016 22:46:49
15748 forum posts
1460 photos

Well, er,....WOW!


Dave Hopkin30/08/2016 22:50:39
3672 forum posts
294 photos

Tony have you considered substituting Depron for balsa in some of the low stress areas, might shave a few oz off her

Tony Nijhuis30/08/2016 23:03:51
609 forum posts
233 photos


My son has already suggested it but I love balsa wood smiley

If all else fails then yes I will. The new fuselage is currently 250g so quite pleased so far

Dave Hopkin30/08/2016 23:42:53
3672 forum posts
294 photos

That love of Balsa shows in every photo and design Tony

and I am 3/4 the way through one of your 48" Vulcans

Simon Chaddock30/08/2016 23:43:19
5773 forum posts
3052 photos


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?

Andy G.31/08/2016 07:50:58
413 forum posts
215 photos

Very impressive, watching this thread with interest!

Danny Fenton31/08/2016 08:50:31
9710 forum posts
4546 photos

Very impressive Tony, and I look forward to reading about the journey

Jon Laughton31/08/2016 09:23:27
1226 forum posts
72 photos

Yes Wow! And we'll done so far - this is going to be very interesting

bert baker31/08/2016 09:44:16
1614 forum posts
332 photos

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


Edited By bert baker on 31/08/2016 09:44:43

Edited By bert baker on 31/08/2016 09:46:25

Tony F31/08/2016 10:41:18
484 forum posts
105 photos
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

Denis Watkins31/08/2016 12:12:47
4631 forum posts
129 photos

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

Tony Nijhuis31/08/2016 15:37:37
609 forum posts
233 photos

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.

Allan Bowker31/08/2016 15:57:31
1640 forum posts
228 photos

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.

Tony Nijhuis31/08/2016 18:11:19
609 forum posts
233 photos

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

Josip Vrandecic -Mes31/08/2016 19:43:06
2993 forum posts
260 photos

From Mr. Nijhuis, Masters of the highest category I did not expect anything less. Modern and classic in one ... electronics and balsa thumbs up ... Greetings from the Adriatic Sea and all the best

Tim Cheal31/08/2016 19:43:25
221 forum posts
54 photos

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.


Tony Nijhuis31/08/2016 21:59:01
609 forum posts
233 photos

Thanks Jo....and yes Tim, will keep you all up-dated


Former Member31/08/2016 23:05:17
3577 forum posts

[This posting has been removed]

Tony Nijhuis01/09/2016 11:49:10
609 forum posts
233 photos

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 timessmiley

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