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Old Oct 10, 2012, 08:18 PM
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Another good sortie!

It was a bit windy but what the heck, I went for it anyways. Conventional type take off no problemo. Landing would have been OK if the landing gear didn't pop off. I had just tacked it on, should have used a bit more glue.

I'm very happy with this experiment so far. Here are a few things I've learned:
  • It is possible to make a VTOL with no control surfaces, although control surfaces are a good idea and will improve flying further
  • It is possible to make a VTOL without having to write code. Any quad system should work...probably a tricopter system too.
  • Fast hover mode seems to be the most stable and easiest to fly. This was the same with my F-35 too.
  • On conventional take off, the bouncing on the ground effects the gyros and limits the power. I still had plenty of power though.

Future work on this project:
  • Good landing gear to be added
  • Aileron and elevator to be added
  • Faster props. I'd like to find 7x6 reverse rotation if possible.

With the elevator added I'll be able to rotate the fans full forward.

Jump Jet, no control surfaces, R&D test #2 (2 min 23 sec)
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Old Oct 15, 2012, 09:33 AM
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Lead.....where are you!?
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Old Oct 15, 2012, 05:19 PM
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Lead.....where are you!?
Traveling for the next two weeks. More VTOL after I get bck home.
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Old Oct 16, 2012, 01:10 AM
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Traveling for the next two weeks. More VTOL after I get bck home.
Yupiiiiiiii
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Old Oct 17, 2012, 01:03 PM
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United States, MD, Annapolis
Joined Jul 2012
94 Posts
Gyro question

Hey, I'm curious how you set up your electronics.

How is the gyro hooked up?

How is the RX hooked up?

Thank you very much, this is a really sick airplane and I'm looking into making a similar model.
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Old Oct 17, 2012, 02:21 PM
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Originally Posted by DoubleOne View Post
Hey, I'm curious how you set up your electronics.

How is the gyro hooked up?

How is the RX hooked up?

Thank you very much, this is a really sick airplane and I'm looking into making a similar model.
It has Crius multiwii board.
Cheers
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Old Oct 24, 2012, 10:12 PM
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Why have the props under/behind the motors instead of over/in front of the motors?
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Old Oct 25, 2012, 10:18 AM
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Why have the props under/behind the motors instead of over/in front of the motors?
3 reasons on this build:

1) Motors and props are slightly more obscure in flight...looks a bit better.

2) Most important is that the axis or rotation of the motor pivots relative to the cg and cneter of drag is important to maintain some pitch authority when motors are tilted well forward. In particular the rear fan tilt pivot point has to bet kept pretty high to maintain pitch down reaction from the rear fans. With a high mount for the pivot the rear fans/motor need to be down to avoid blasting into the wing in hover mode.

3) To avoid prop/wing clearance issues when tilting the rear fans yet keeping the rear fans/motors as hidden as practical.
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Old Oct 28, 2012, 07:46 PM
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Finally back home after two weeks. Had some RC time today. The jet now has an aileron and an elevator. Next test will be with full tilt of the fans for forward flight. Still no special programming. Just a regular quad, with all other functions (tilt, elevator, aileron) are from the Rx direct.

The weather is looking good for a Tuesday or Wednesday test.
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Old Oct 28, 2012, 11:58 PM
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Where do you think you'll have the cg at for the next test flight? I would think tail heavy would be best since the quad is still using differential thrust for roll input which would act for yaw in ff. You think it would help keep the nose down in a bank? I hope it all works out because this is turning out to be surprisingly easy!
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Old Oct 30, 2012, 07:09 AM
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Where do you think you'll have the cg at for the next test flight? I would think tail heavy would be best since the quad is still using differential thrust for roll input which would act for yaw in ff. You think it would help keep the nose down in a bank? I hope it all works out because this is turning out to be surprisingly easy!
I'll probably go for neutral fixed wing cg. Tail heavy would be asking for pitch problems in forward flight.

In forward flight, roll inputs from the Tx will deflect the aileron for roll and also cause a yaw input form the motors in a coordinated direction for the turn.The jet should turn and roll fine ...I think.

I'm hoping to test this evening.
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Old Oct 30, 2012, 08:08 PM
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Full tilt flight report

I had nice weather for testing this evening. The purpose of the testing was to check out flying on the wing with full forward tilt of the fans. This means most of the control was transferred to the flying surfaces. Pretty uneventful... the transition was smooth and the controls worked as expected.

This experiment is just about done for me. I wanted to see if VTOL (horizontal transition type) could be accomplished without any extra multiwii programming...it can!

It may not be better than some of the cool stuff that can be done with some programming but it is much easier.
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Old Nov 01, 2012, 10:32 AM
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Serbia, Central Serbia, Belgrade
Joined Mar 2011
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Hi Leadfeather,

Forgot to ask: Are you using unmodified MultiWii code (which version?), or you are using modified MultiiWii for VTOL code? Also, what is driving the motor tilt servo, Arduino board or straight from Rx, AUX channel? Do you still have time strech on this servo?

Are the gyros disabled in fff and how, if unmodified code is used?
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Last edited by jusjak; Nov 01, 2012 at 10:43 AM.
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Old Nov 01, 2012, 11:11 AM
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Originally Posted by jusjak View Post
Hi Leadfeather,

Forgot to ask: Are you using unmodified MultiWii code (which version?), or you are using modified MultiiWii for VTOL code? Also, what is driving the motor tilt servo, Arduino board or straight from Rx, AUX channel? Do you still have time strech on this servo?

Are the gyros disabled in fff and how, if unmodified code is used?
Yes, unmodified multiwii code V 1.9 set up for a quad copter.

The tilt servo is driven directly from the Rx with a "servo slower" device between the Rx and servo.

No servo stretching in the code. The 90 degrees of tilt is just from the servo/Tx /linkage set up.

The control surfaces are also direct from the Rx.

The gyros are not disabled in forward flight. At all times the fans operate from the unmodified multiwii code...simple as possible.

This is a simple approach to VTOL and probably a good 1st step for someone making the leap from a multicopter to a VTOL craft.

Note that it didn't fly noticeable faster with full (90 degree) tilt compared to 70 or 75 degree tilt; so to maintain some extra control you may want to consider not going full tilt forward on the fans for forward flight.
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Old Nov 01, 2012, 07:16 PM
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Serbia, Central Serbia, Belgrade
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Thanks, that's how I understood it from previous posts, I am just doublechecking.

I like this minimalistic approach as I think it is the way to start in VTOL. With minimalistic/simple approach I was able to learn to fly helicopters, using simple quad with wooden protectors from crash. That way the fear from crash was eliminated and the piloting learning curve got much steaper.
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