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Old Oct 01, 2012, 08:08 PM
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Joined May 2006
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Idea
Jump Jet, vectored thrust experiment; maiden flight success!

Here's what I've been working on this last little while. A VTOL jet configuration that may work with any flight control board, with no special programming required.

With my other VTOL projects I had noticed that the easiest flying was in what I called "fast hover" mode...fans tilted forward about 45 degrees. Now I want to see if I can take it one step further. I want to tilt the fans even further; but not all the way forward; and see if I can control the jet using just the fans to provide attitude control...no control surfaces.

In hover and fast hover it is flying as a quad copter; should be no big deal.

In forward flight there will be enough tilt left in the motors, and the motors are arranged so that the fans will still provide pitch control but it will not fly on the props any longer, most of the lift will be coming from the airframe in this mode. Roll inputs from the stick will cause a yaw which; due to the swept wing; should induce a roll. I'm hoping to be able to do loops and rolls but i will settle for controllable flight.

So in point form:
  • 4 fans
  • 1 servo to tilt the fans, tilt servo plugs into Rx with servo slower
  • no control surfaces or servos
  • no special programming, just the standard MultiWii ( or KK) quad. In the past, programming has always been the most difficult part of the project and I had to rely on cass3825 to do the required coding.
  • EPP airframe to get me through the learning curve.
  • no distinct transition point... I hope.

I'll be starting with 8x4.3 props, but if all goes well I may switch to something faster like a 7x6 prop later.

So far the build is coming out pretty light. This always helps whether hovering or flying on the wing.
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Last edited by leadfeather; Dec 23, 2013 at 08:28 AM. Reason: typos
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Old Oct 01, 2012, 10:32 PM
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I think it looks cool! The concept seams sound enough to me.
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Last edited by RCvertt; Oct 01, 2012 at 11:25 PM.
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Old Oct 03, 2012, 12:05 PM
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Originally Posted by RCvertt View Post
I think it looks cool! The concept seams sound enough to me.
If we take the concept a little further and raise the rear fans above the center of drag in forward flight, then we can maintain pitch control ( using fans only) with full forward tilt. Hmmm might have to think of a good looking air frame that could use this arrangement if this first experiment works out.
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Old Oct 03, 2012, 12:52 PM
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saweet
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Old Oct 03, 2012, 03:47 PM
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Cool idea
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Old Oct 03, 2012, 09:24 PM
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I made a little progress tonight. The rest of the foam air frame is cut out and the power harness is made. It begins to be more fun when it starts to look like something that might fly.
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Old Oct 05, 2012, 05:14 AM
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Joined Jan 2012
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Cool idea to make hover jet as I have a simular one

leadfeather

I like your idea as I had an interesting idea of my own not sure how to make it work but in the crude design stages now , as I also have to figure out how to make my Enterprise-A fly as it is to underpowered for the frame I built, but getting Back to the Jet I have designed mine between the avengers movie and the green lantern movie
using only two big fans on the wings which will I hope bring the craft off the ground and be able to pitch to 45%angle to bring it forward the have the edf engine which is in the fuselage to be able to take off quicker and hopfuly and do stunts I am still learning how to do that as I am still learning how to fly RCs mainly with my two playmates one kind of bet up one and one the is in almost prestine shape. my drawings are crude right now but tell me what you think of my idea



Dave

PS thanks for being one of my Friends
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Last edited by AzTrekie; Oct 05, 2012 at 05:39 AM. Reason: add drawings
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Old Oct 05, 2012, 07:57 AM
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Dave,

You design looks cool.

I am concerned you may be too ambitious at this time with this project. VTOL is one of the hardest things to do in RC both in terms of design and building skills, and also flying skills.

For this type of VTOL ( a transitioning jet) ; to be successful; you should have pretty good 4 ch fixed wing flying skills and also some multi-copter or 4 ch helicopter flying experience.

With your design I have a couple of concerns:
  • If there are only two lift fans, hovering stability is going to be pretty tricky.
  • With the large holes in the wings there is not much lifting surface for forward flight...wing loading and flying speed will be very fast.
  • With the anhedral tips you'll need ailerons for forward flight. The anhedral tips give a reverse yaw/roll coupling. With only two fans you'll also need an elevator for pitch control in forward flight
.

Good luck with what ever you decide to do.
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Old Oct 05, 2012, 08:28 AM
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Awesome!...Allways,i liked the Harrier
Cheers Lead
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Old Oct 06, 2012, 02:44 AM
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AzTrekie's Avatar
Joined Jan 2012
216 Posts
Thanks for your advise

Quote:
Originally Posted by leadfeather View Post
Dave,

You design looks cool.

I am concerned you may be too ambitious at this time with this project. VTOL is one of the hardest things to do in RC both in terms of design and building skills, and also flying skills.

For this type of VTOL ( a transitioning jet) ; to be successful; you should have pretty good 4 ch fixed wing flying skills and also some multi-copter or 4 ch helicopter flying experience.

With your design I have a couple of concerns:
  • If there are only two lift fans, hovering stability is going to be pretty tricky.
  • With the large holes in the wings there is not much lifting surface for forward flight...wing loading and flying speed will be very fast.
  • With the anhedral tips you'll need ailerons for forward flight. The anhedral tips give a reverse yaw/roll coupling. With only two fans you'll also need an elevator for pitch control in forward flight
.

Good luck with what ever you decide to do.
Lead
Thanks for your advise I have some other ideas on the burner a vector kite type ( dragon) http://www.rcgroups.com/forums/showthread.php?t=1740834 , a simple type of plane I call the my simple plane here at http://www.rcgroups.com/forums/showt...0#post22926605 and I still have to figure out how to get my Enterprise -A flying all details on my blog at http://www.rcgroups.com/forums/member.php?u=398824

Dave
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Old Oct 06, 2012, 09:16 AM
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Quote:
Originally Posted by AzTrekie View Post
leadfeather

I like your idea as I had an interesting idea of my own not sure how to make it work but in the crude design stages now , as I also have to figure out how to make my Enterprise-A fly as it is to underpowered for the frame I built, but getting Back to the Jet I have designed mine between the avengers movie and the green lantern movie
using only two big fans on the wings which will I hope bring the craft off the ground and be able to pitch to 45%angle to bring it forward the have the edf engine which is in the fuselage to be able to take off quicker and hopfuly and do stunts I am still learning how to do that as I am still learning how to fly RCs mainly with my two playmates one kind of bet up one and one the is in almost prestine shape. my drawings are crude right now but tell me what you think of my idea



Dave

PS thanks for being one of my Friends
Something similar to this?



Stay tuned: http://www.rcgroups.com/forums/showthread.php?t=1683638
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Old Oct 06, 2012, 01:14 PM
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sre somthing simular

Quote:
Originally Posted by rimshotcopter View Post
Something similar to this?



Stay tuned: http://www.rcgroups.com/forums/showthread.php?t=1683638
yes using hat exact fan whith a faster brushless motor
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Old Oct 06, 2012, 01:21 PM
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Quote:
Originally Posted by AzTrekie View Post
yes using hat exact fan whith a faster brushless motor
LOL, Interesting.
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Old Oct 06, 2012, 07:05 PM
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First hover

Just hovered it for the first time. So far so good. I need to do a bit of PID tuning and once this is done I will then glue on the rest of the airframe.
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Old Oct 06, 2012, 09:31 PM
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Hover test looks good. Got to let that bird out and set it free

Quote:
Originally Posted by leadfeather View Post
If we take the concept a little further and raise the rear fans above the center of drag in forward flight, then we can maintain pitch control ( using fans only) with full forward tilt. Hmmm might have to think of a good looking air frame that could use this arrangement if this first experiment works out.
Be interesting to see how well it works, especially at slow speeds. I'm thinking you might have to land a little faster is all since all your commands will propel you forward a little bit.

Also curious how good pitch will be since the fans aren't spaces as far from the fuselage as the yaw commands will be in forward flight.
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