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Old Apr 22, 2014, 08:24 PM
Registered User
United States, TX, Waco
Joined Aug 2012
3 Posts
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Slow Flying VTOL EDF Jet Project

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 maneuverability)
-I am concerned with the battery usage...

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 thinking to use a modified Quadricopter control board, set up in the '+' configuration, 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 going 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 successfully 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.
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Last edited by ezgo394; Apr 22, 2014 at 08:38 PM.
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Old Apr 22, 2014, 09:40 PM
The "pro" in procrastination
Steve85's Avatar
Canada, ON, Kingston
Joined Mar 2004
2,660 Posts
Hey EZ,

Welcome to RC Groups and to RC. You've certainly set yourself a daunting modelling and engineering challenge as your first attempt at designing and building an RC model. I don't mean to rain on your parade, but FPV, multiple EDF, VTOL, variable incidence wings, Fowler flaps, and gimbal-mounted cameras each individually qualify as advanced techniques. To put all of them together into your first design and build is exceptionally ambitious.

I'd recommend reading through the Electric Jets Section, the FPV Section and the UAV Forum for an idea of the technical complexity of each of the component capabilities you'd like to include. I'm sure if you posted your post above in one of the EDF forums, you'd get lots of advice, most of which would not be encouraging, but which might eventually prove useful in rescoping your first project to something you can realistically hope to complete. Good luck.

Steve
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Old Apr 22, 2014, 10:29 PM
Registered User
United States, TX, Waco
Joined Aug 2012
3 Posts
Hello Steve,

Thank you for your reply and your welcome.

Yes, I realized that early on. I'm comfortable with the challenge and I'm not in any rush. I've designed several aircraft before (well, external views only) but I feel I have a good understanding of the design work that goes into it all. Once I get preliminary drafts drawn up, I'll draw it all up in a CAD program, get all the parts cut and start assembly. Of course, assembly is a whole different thing, but we'll get there.

Concerning the points that you raised, several things:

-FPV: My brother has successfully designed and flown a quadcopter with an FPV setup and when I get to that point, I'll have his know how to help me.
-Multiple EDF: Yeah, that'll be a tough one for sure... That's where I will need help
-VTOL: As I said in my first post, I know that VTOL itself will be easy to do, but to get any kind of maneuvering action, that will be hard as I will have to set up a control board for that.
-Variable Incidence wings: I wasn't going to make this one too hard. The fuselage will be a rectangular shape, so above the main turbine, where the wing roots meet the fuselage, I was just going to cut out that section (just like on the F-8 Crusader) and make it one whole moving piece. And then to move it up and down, use a linear actuator nestled in between the vertical front EDFs and the main EDF inlet duct to push the wing up and down.
-Fowler flaps were actually one of the newest additions. I was thinking of a split flap, or even just a regular flap, so this one is still up for debate. I actually do want to try to figure the fowler flap out.
-Gimbal mounted camera: Again, with my brother, he has built and tested a gimbal setup and has made some really nice videos with it, so when it comes time for that, I'll look to him for help and guidance.


I'll for sure post in the EDF forums. I wasn't sure I was in the right place anyways..


I feel like this won't be too bad. Yes, it's ambitious and if I crash and burn (literally), then it's ok. I'll get up and keep going. It's a big plane and even bigger because of all the extras, but I look forward to designing, building and flying it, even if it doesn't pan out.


EZ
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Old Apr 23, 2014, 03:44 AM
Registered User
United Kingdom, England, Salisbury
Joined Feb 2011
3 Posts
Hi EZ,

As Steve has just said you are certainly jumping in with both feet so good luck. You might find the attached link good for some ideas although this is a mixed Tricopter/Wing rather than a quad. http://www.birdseyeview.aero/products/firefly6

George
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Old Apr 23, 2014, 09:40 AM
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Ran D. St. Clair's Avatar
United States, CA, Sunnyvale
Joined Dec 2006
808 Posts
Welcome to the forum. I want to be encouraging, I really do, but right now you need the truth more than encouragement. This project and your expectations for it are unrealistic in the extreme. You are looking at a 5 year project at a cost of many thousands of dollars, and you are going about it in a way that is least likely to succeed.

Sadly, I know you won't hear this, or understand that I am trying to help you, not discourage you. You need to start smaller, cheaper, and far simpler. Develop some experience and build some success in some of these individual technologies, and most importantly, have fun and enjoy the process of getting there, because there will be many crashes and setbacks along the way.

I have seen people take this path many times. It almost always ends with them giving up and moving on long before they have even a first non-flying prototype. Those that do actually manage their big complicated heavy dream machine are usually so discouraged by the inevitable crash and total destruction of all their hard work that they never come back.

Many folks on this forum would love to help you with answers to a thousand questions, but you don't even know what questions to ask yet.

Good luck, and please prove me wrong.
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Old Apr 24, 2014, 10:22 PM
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Joined Jan 2010
2,876 Posts
I mentioned in his other Thread, I wouldn't expect project like this to be lighter than 8-10kg AUW, pretty tough task to make it hover. I have almost succeeded hovering my 15.5kg "TRIPTYCH" on it's maiden flight for 1/2 a minute, tho not intentionally. One 127mm fan with two 90mm boosters on each side allowed me to hover this monster loaded up with 6.5 kg of lipos before I managed to bring it down with minimal damage . Cause, much too tail heavy and too much up thrust, J.
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