EDF Harrier VTOL - RC Groups
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May 12, 2016, 05:17 PM
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Build Log

EDF Harrier VTOL


Dear all

Inspired by all the great work and effort that is here on the forum (especially Joel Vlashof’s VTOL, with all the supporting members of the forum), I have decided to build a Harrier myself: this is how far I have come, I would welcome your comments, especially on how to go further:

I have designed the Pegasus myself in ScetchUp, and a friend made the 3D prints. All of the measurements are made up by me based on readings from the internet and this forum (especially Joel’s inspiring work).

4 large nozzles (lift)

The FSA of the 70 mm EDF is divided into 4 equal parts that go to the 4 big downward/tilted nozzles. To improve airflow and minimize turbulence and pressure loss I inserted turning vanes in each 90 degree bend. According to my digital kitchen scale, I have an approximately 80% efficiency when the airflow is channelled through the Pegasus. The nozzles are designed in such a way that through a belt drive (one belt for each nozzle, connected by shafts and operated by a servo) will be able to tilt backwards, controlled by the OpenAero time function between p1…p2 transition. It works, in the mechanical sense, but I have decided to deal with the transition after successful hover. This is yet to come…

4 smaller vanes (control)

The roll/yaw/pitch control vanes have a 10mm diameter (just a guestimate size). There are 2 roll control pipes (one to each wing) and 1 yaw and 1 pitch, both at the end of the airplane. For the roll/yaw/pitch vanes there is 20 gr thrust each (I know from Joel’s previous post that this is way too low, about 10x more would be needed).

My roll/yaw/pitch valves are up & down, meaning, when for example rolling right: one roll valve in the wing is blowing up, while the opposite valve is blowing down. Theoretically this gives me 2x20 gr of roll control thrust, but still not enough. Pitch and yaw control are directed to the back of the harrier, with one valve each, where the valve is also capable to blowing air of up or down (for pitch) and left/right (for yaw).

KK 2.1

I have flashed the board with the OpenAero2, which only controls the 4 servos (the roll/yaw/pitch servos and the transition servo for moving the lift nozzles when transition from P1 to P2). OpenAero seem to work nicely on the ground (ie the control valves move on stick command and on stability/autolevel if I move the plane.)

The EDF is controlled through the Receiver/ESC, not through the KK 2.1

here is a short vid on how it looks on the ground:
Full equipped (0 min 48 sec)



Thrust/Weight:

The Pegasus with the test rig weights 730 gr, including EDF, ESC, Batt, 4x10gr servos, KK 2.1 flight controller and all the 3D printed plastic. The 4 downward big nozzles provide 720 gr thrust, the 4 control valves have the remaining 80 grs.

Hence this damn thing does not lift off , which I actually expected after receiving the first 3D print, but continued the build to have a feel for what it should look like when all is assembled.

Questions:

It might be basic, but how to simplify the power to the KK2.1 to have only 1 battery? Now I have 2 different batteries that are connected to the KK 2.1

- one battery with EDF’s ESC+BEC that is connected to the Receiver which is connected to Kk2.1 with servo cables (hence the M1 circuit receives power)

- one smaller battery with a simple BEC for the servos, connected to the KK2.1 to M8.

Is it possible to have just one battery (SEE PICTURE) to which with a Y cable I connect both the ESC+BEC and the BEC and then supply power to the Receiver (and subsequent M1 circuit) and then the BEC would power the M8?

Another question:

Do you have any suggestion how to proceed with this whole thing? I know I need to step one size up to

EDF 90 MM, but to do so in my view I have 2 options:

1) two step option: I could try to increase efficiency by redesigning the EDF 70 mm Pegasus, and try

to get as much that it would lift itself and see whether the control works at all even if weak. And

only after that I upgrade to the 90 mm EDF.

2) Go straight to 90 mm EDF with this design and take it from there.

3) There is also a 3 rd option – what Joel was suggesting: next to the 90 mm EDF to have a 50 mm


I have looked at on hobbyking for the Mad Thrust 90 mm EDF with 5200 gr thrust, but have not ordered yet.

This is it for now, wonder what you guys think.
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May 12, 2016, 08:12 PM
jofro
Full credit to your imagination and effort, nice toy gadget to play with on the bench but I hope you don't ever expect this thing to fly, do you?
May 12, 2016, 08:36 PM
Registered User
Looks heavy as fk.
May 12, 2016, 10:41 PM
Registered User
Tumbler's Avatar
That is impressive as all he--!!! Wouldn't it be easier to get more thrust going up to something like 120mm fan?
May 13, 2016, 09:13 AM
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Larry Dudeck's Avatar
Very impressive. But obviously you need a significant increase in the t/w ratio. Some experimentation with motor kV and higher cell count might get the t/w greater than 1:1 but the price you will pay is greatly reduced flight times due to a small capacity battery. And that's without an airframe.

Add those pesky things like wings, control surfaces, etc., etc. and the t/w suffers greatly...
May 13, 2016, 09:54 AM
Registered User
Quote:
Originally Posted by Tumbler
That is impressive as all he--!!! Wouldn't it be easier to get more thrust going up to something like 120mm fan?
yes, this is the next move. i had this cheap Chinese 70 mm EDF lying around and thought I have a go with it - with this 800g of thrust, it was never meant to fly, but to experiment only.
May 13, 2016, 10:45 AM
Registered User
nofreee's Avatar
Love it. Very impressive 3D work. Can't wait to see it once you get your power system sorted out.
May 13, 2016, 12:10 PM
What goes up...
Twisted Wings's Avatar
Love it, don't give up!
I've been mulling over the thought experiment of this for some time so its nice to see someone has fleshed it out.
I was settling more on an light weight 80mm or even the 75mm from hobbykings tornado viper jet on 6s for grunt, and utilising the kk board with vtol to control the 4 ducts independently to control pitch, roll and yaw, removing the weight and complexity of the puffer control system.
Weight reduce the ducting as much as possible, use your jedi CAD skills to remove all unnecessary material from the 3d print to the bare minimum that holds shape and carbon tow any critical points. Or can you hot form ducting from depron?
Subbed.
May 13, 2016, 12:23 PM
What goes up...
Twisted Wings's Avatar
Check out Clickety's pusher harrier for a lightweight airframe to fit this to when the bugs have been worked out...
https://www.rcgroups.com/forums/show....php?t=2629568
May 13, 2016, 05:27 PM
EDF Jet Jam 2017, June 15-18
Kevin Cox's Avatar
Very impressive work!
May 13, 2016, 06:00 PM
Registered User
Quote:
Originally Posted by Twisted Wings
Love it, don't give up!
I've been mulling over the thought experiment of this for some time so its nice to see someone has fleshed it out.
I was settling more on an light weight 80mm or even the 75mm from hobbykings tornado viper jet on 6s for grunt, and utilising the kk board with vtol to control the 4 ducts independently to control pitch, roll and yaw, removing the weight and complexity of the puffer control system.
Weight reduce the ducting as much as possible, use your jedi CAD skills to remove all unnecessary material from the 3d print to the bare minimum that holds shape and carbon tow any critical points. Or can you hot form ducting from depron?
Subbed.
Txs! I also thought about controlling the 4 ducts, should be interesting to see if anyone gives it a try. One would need 4 servos for the 4 ducts, and another one for the tilting of the ducts, but with is openaero2 it should be possible.
Thanks for the harrier body suggestion, although it's a bit further away, but I was already wondering how am I going to build the body itself.
May 13, 2016, 06:27 PM
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v22chap's Avatar
another cool build ... love the 3 D print job ... keep it going and good luck
May 13, 2016, 06:29 PM
Registered User
Ran D. St. Clair's Avatar
Quote:
Originally Posted by gbolyo19
Is it possible to have just one battery (SEE PICTURE) to which with a Y cable I connect both the ESC+BEC and the BEC and then supply power to the Receiver (and subsequent M1 circuit) and then the BEC would power the M8?

Do you have any suggestion how to proceed with this whole thing? I know I need to step one size up to EDF 90 MM....
Your proposed sketch for power distribution is a very standard setup and will work fine. Unrelated to power distribution, The main throttle control to the ESC usually comes from M1 (OUT1), which means it is automatically powering both the KK2 and the RX. This also allows the KK2 to provide altitude damping stability feedback. It should be flyable without altitude damping, but will require a bit more pilot skill.

As for the path you are on, I would encourage you to think smaller, not larger. Without getting into the math or the physics, there is a reason ants can lift 15X their own weight, but humans can't. If you keep making this thing larger then it just weighs more, so you have to make it larger still, so in the end you are just killing yourself. There are also good economic reasons to go smaller, not to mention that it will be less subject to crash damage when it is small and light.

Your problem is weight. I suggest a hybrid build technique where you use 3D printing to make the sophisticated shapes you need and then lay up thin carbon fiber on top to make the actual parts.
May 14, 2016, 03:32 AM
Registered User
Finally someone who understands the Harrier keep up! Do learings from that edf en try an big Edf one day i am allready a big fan of youre work

Kind regards Joel
May 14, 2016, 06:55 AM
Registered User
That is a very impressive piece of work!
I must agree with Ran D.St.Clair that the issue the weight. All that 'engineering' is not conducive to light weight.

To get to a practical thrust to weight, say 2:1 for such a 'test' rig, you will need to rigorously adopt the principle "Is every component only just strong enough for the loads it has to bare?" and at these small sizes this is likely to require some very imaginative use of materials.

I will be following with interest.


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