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Old Apr 22, 2014, 10:38 PM
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United States, TX, Waco
Joined Aug 2012
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Slow Flying VTOL EDF Jet Project (1)

Hello all.

A quick introduction; My name is Ethan, although I prefer EZ, I am 20 years old and attending a technical school for a degree in Building Construction. I have had a passion for plane since I started high school and have played Microsoft Flight Simulator X for the past 6 years, amassing over 2500hrs, so planes are not new to me.


RC flying, however, is somewhat of a new endeavor for me. I have always been interested in it, but one of the reasons I did not get too far in it was because I hate flying LOS. However, with the FPV technology getting much better, I feel like now is a good time.
My brother has been flying quads for some time now and I have tried to get into it but I'm more a fixed wing nut. What I really wanted to do was fly slow and also be able to hover (yes, VTOL) and came up with several ideas.

The one I settled on is a setup like the Yak-38. I don't want to write a big text block, so I'll just list all of the things I want to do with this (you may have to refer to the 3 pictures I have linked to better understand what I'm describing):

POWER
-2x 70mm EDF right behind the cockpit, to provide lift in hover mode
-1x 120mm EDF in the middle of the fuselage which provides thrust to two thrust vectoring nozzles in the rear of the fuselage, that swivel up and down for forward flight and hover
-2x 70mm EDF buried in the wings, for forward flight, and for hover will have 2 doors that will open downwards in hover mode to provide additional lift (and lateral manueverability)

WING
-The airfoil will be thick to provide more lift and slower speed
-The wing will move up and down, much like the Vought F-8 crusader, tilting up about 15*-20*,
-Fixed or automatic slats that will provide increased lift when the wing is tilted
-Either a short span (3ft) or a long wing span (8ft). If I went with a large span, the root would most likely be 8", and a short span would most likely be 10-12"
-Fowler flaps (still working on extension/retraction mechanism) to extend the chord

FUSELAGE
-Width 5 1/2" x Height 7 1/2"
-Provisions for gimbal mounted camera along side standard FPV flight camera

PRELIMINARY SKETCHES (Had to take pictures due to lack of scanner)
Basic Concept Sketches
http://www.majhost.com/gallery/ezgo3...422_192832.jpg
First Scale Rendition at 1/4"=1"
http://www.majhost.com/gallery/ezgo3...422_192837.jpg
Basic Side View
http://www.majhost.com/gallery/ezgo3...422_192922.jpg

FLIGHT CONTROLS
-For Forward flight, standard airplane controls will work fine.
-For hover, standard airplane controls will also work, but it will not respond well to any kind of maneuvering inputs. For that, I was thinknig to use a modified Quadcopter control board, set up in the '+' conficuration, rather than an 'X'. The only problem with that is how to transition the controls from forward airplane flight to hovering flight.

FLIGHT TESTING
I also have it figured out how I'm gonig to test it when I get to that stage.
Pretty much the first aircraft that will be made will only be the fuselage and the wings to the engines. Each engine and nozzle (and pretty much everything that will affect CoG) will be screwed in and will have several alternative mounting points. Then flight testing will come with the aircraft attached to a small tether and seeing how it balances (and it's payload cap.)and whatever needs to be moved will be moved forward or back. Once the aircraft is succesfully balanced, then the full wing will go on, along with all skin and a mock payload and hover tested again. After that, forward flight only testing, hover only testing, and then once enough data has been compiled then test the full flight spectrums.


So, that's pretty much it.

Most comments are welcome (aside from size comments). I'm moving slowly along and I'm just looking for some opinions on the whole thing, plus engineering input.

I do realize this is ambitious, but I am not deterred. I feel very confident that I can do this, even though I've done nothing of the kind before.
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Old Apr 23, 2014, 12:46 AM
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CoolerByTheLake's Avatar
United States, MN, Hermantown
Joined Dec 2008
5,429 Posts
Have you come up with a projected weight?

As I see it, 5 ESC's . Batteries= One each for the 70's ( they will need it for hovering) and 2 (more than likely), 5s or 6s for the 120mm?
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Old Apr 23, 2014, 03:25 AM
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Joined Jan 2010
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Pretty challenging project, I wish you good luck with it. You will need at least 3.5kg in batteries for a short flying sessions with the power set up you mentioned, I project your AUW might be in 8-10kg range. Pretty tough task to make it hover, looking forward to your progress, J. from J F Jet Studio.
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Old May 06, 2014, 11:08 PM
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wicked project! keep on it, this is the future.
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Old May 07, 2014, 07:53 PM
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Any progress on your project?
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