FlyingWings Venturi VTOL

iPeel · March 25, 2015, 02:39:17 PM

** Long post alert **

Rob at FlyingWings and I have long talked of having a go at building an airframe to make good use of the PX4 VTOL branch. Rather than the boring multi-rotor / flying wing fusion seen in many VTOL deployments, this project offers a configuration that uses a dual tractor prop design with a combination of the two contra-rotating props and intricate elevon control to maintain positional stability when in VTOL mode and at the flick of a switch you can transition into level flight, the controls adapt between multi-rotor and flying wing based on the current mode. This offers up the possibility of a VTOL capable craft with long range capabilities; the field applications of this are endless, and instead of going for the low hanging fruit like military contracts or conservation projects we are going straight for the big prize of YouTube humiliation.

From what I can see the only implementation so far is on a TBS Caipirinha, which looks a bit cobbled together and chosen mainly for it's lightness and durability (nothing like having faith in your project...). We've decided to go for it in style and modify the FlyingWings Venturi Evo for a twin prop tractor configuration. The benefit of this airframe is it's relative lightness for its size whilst still having a good amount of space in dedicated bays for flight controllers and other equipment, making a nice neat build which should please Coyote. Rob has done a stellar job and provided me with a Venturi Evo and custom nacelles to take the twin props, there's a lot more to it than that of course as we've had to redesign the spar layout to accommodate the swapping around of the equipment and battery bays, necessary to keep the CG in the right place after swapping the power systems from back to front. There will also be custom winglets which double as a vertical stand when taking off and "landing".

It's always good to work to a brief so we've set ourselves the challenge of a VTOL take-off, 10 KM out and back run followed by a VTOL landing. If we can manage that then we have an interesting capability in a flexible airframe, if we fail then we will undoubtedly have some YouTube gold.

The code itself runs on the PX4 platform, which the Pixhawk is based on and therefore this is the hardware we'll be using to host the code as all the necessary gubbins are integrated into a lovely neat package. The iPeel Technical Centre of Excellence has taken delivery of all the necessary kit to build the project and I'll be updating this thread with the ongoing project. I'm expecting this one to last a bit longer than my usual builds as well as probably making up a few new words as I attempt to get the code running.

So far the parts list is running at:

Customised Venturi Evo with bespoke nacelles and spar.
Custom elevons (more details as the project runs on).
Pixhawk controller + relevant bits running the master branch of PX4 Autopilot software (not ArduPilot).
MyFlyDream Telefly Pro for tracking.
MinimOSD running OSDExtra.
2x Turnigy 3542/5 1250Kv motors.
2x Plush 60a ESCs.
2x Hitec 645MG servos.
2x APC 9x6 E props (one CW, one CCW).
Effio-V board cam.
1.3Ghz 800mw VTX.
SJ4000 camera.
DTF-UHF OpenLRS RX running OpenLRSng.

Battery-wise I'm undecided as to whether we'll use standard 3300Mah 4S nano-techs or use the lighter weight, higher capacity Panasonic NCR18650e cells in our own configuration, the C rating of these cells may not be enough for VTOL though. For the VTOL capability the Plush ESCs will need to be flashed with BLHeli which I've already checked can be done and be responsive enough. The motors weren't my first choice which were SK3 1250KVs but these aren't in stock and the regular Turnigy jobs should have enough grunt I'm hoping. I've also got an extra cam and video switcher on standby to allow a bottom-view camera which can be used as a ground level view when we're in cruise and a forward view when we're in hover.

I'm hoping to make this a nice, interesting project to follow, and will get as many pictures up of the build process as possible along with the configuration steps as very little online documentation exists on this project. Our entry into the VTOL sector has already seen Google run for the hills, Amazon watch this space!

More details on the PX4 VTOL project can be found here but what you really want is a nice video showing it off, so here you go:

http://youtu.be/acG0aTuf3f8

Cheers,

Neil.

CurryKitten · March 25, 2015, 02:51:35 PM

This is an excellent project. From what you said earlier, I assumed a quad or tri plane into a dual proper normal setup.

The demo looks pretty impressive..albeit possibly the worst camera work ever from that quad. The bi-copter style hover looks very impressive, but tricky in the practicality stakes if you are using FPV to take-off/land.. On the plus side if you can flick a switch an lknow it will come into hover happily by itself, then a very easy goggles off and LOS land.

Looking forward to watching this unfold :)

iPeel · March 25, 2015, 03:00:13 PM

Thanks Wayne. :)

We've been thinking about the FPV take-off and landing dilemma which is why I have the second camera and video switcher on standby. I'm not concerning myself with that for phase one though as the thought of not maintaining control line of sight with a 1.5 metre 2.5Kg twin prop beast running pre-alpha software at head height isn't appealing.

Neil.

skyscraper · March 25, 2015, 04:33:22 PM

PX4 ... Good Choice :D

Loved the transition to forward flight in the vid..

Looks like a great project !

regards
Andy

Brucey · March 25, 2015, 06:55:45 PM

Quote from: iPeel on March 25, 2015, 02:39:17 PM
The iPeel Technical Centre of Excellence

I just cant work out an acronym...TIT CE

I look forward to helping you gather the foam from across the field on test day ;D

I think just a normal twin tractor version of the Venturi could be awesome, more efficient and less noise.......... man I'm sounding old! Did I tell you I've just bought a Mondeo! :'(

iPeel · March 25, 2015, 08:11:41 PM

Sorry Brucey, I would have replied earlier only I was out having an amazing flight while you were stuck working! :P I would have taken you up on buzzing the tower only I'm pretty sure I wouldn't have made it back...

Yes, it'll be interesting to see how the airframe flies in that configuration, shame I'm not putting twin SK3 motors on it as that would have ripped along, as soon as they're back in stock I'll probably find myself ordering a pair.

You're not even a dad yet and you're having your wings clipped mate, I hope you're keeping the beast for old times sake?

Brucey · March 25, 2015, 09:47:43 PM

Yeah the weather was great... As I looked out of the window... Sob...

Coyote · March 25, 2015, 09:59:24 PM

Looking forward to seeing this materialize :)

iwan_canobi · March 25, 2015, 11:53:44 PM

Sounds like an interesting project! The video looked good (well, the actual video was terrible as mentioned, why put a camera with an arm and motor in view?!?) and the transition to forward flight was nice and smooth looking!

Will be great to see it on a big bird like the Evo!

BigT · March 26, 2015, 09:43:08 AM

How about a camera mounted on the top of the goggles that you switch to as you transition to hover to give immediate line of site? Would save having to whip the goggles off at a critical moment. Can the pix hawk do auto landings like the APM?

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iPeel · March 26, 2015, 08:03:45 PM

Quote from: BigT on March 26, 2015, 09:43:08 AM
How about a camera mounted on the top of the goggles that you switch to as you transition to hover to give immediate line of site? Would save having to whip the goggles off at a critical moment. Can the pix hawk do auto landings like the APM?

You mean like the Skyzone goggles? Neat idea and I look forward to getting as far as having that problem to solve! The Pixhawk can actually run the APM:Plane firmware or it can run the PX4 firmware, when running the APM:Plane firmware you get all the features of the original APM ++, as the board is much faster. I'm not sure what the true capabilities of the PX4 firmware are as it's very different to APM:Plane and will report back as soon as I've had a dabble in the configuration screens.

iPeel · March 26, 2015, 08:15:07 PM

So, a quick update as all the bits and bobs are here:

The Pixhawk is really nicely packaged and the unit itself looks like it's really well built. Size-wise it looks much smaller than it should be but is actually a little bit bigger than an MFD:

There'll be plenty of room in the equipment bay for it and the GPS et al.

The wing has been pre-cut on the wire cutter for the nacelles:

The nacelles themselves look really nice and are reinforced at the sides to take any of my trademark landings:

What I think I will struggle with is the order of the build. Normally I would fit the electronics then laminate over it. I think I'm going to have to laminate the wings then cut away the laminate for the nacelles then glue them in place, quite when I fit in the ESC lines for the motors I don't know.

Another thing I'm stuck considering is when to build the centre section:

I want to leave the ribs which run across the centre section from side to side until last, because only then will I really know how to balance up the batteries and that will determine where I glue the ribs in. I will likely build most of the centre section without the ribs then hack those in last.

Urgh! I'm beginning to realise how big this build is going to be even before I get round to the really cool stuff!

Neil.

skyscraper · March 27, 2015, 10:21:36 AM

Quote from: iPeel on March 26, 2015, 08:03:45 PM
Quote from: BigT on March 26, 2015, 09:43:08 AM
How about a camera mounted on the top of the goggles that you switch to as you transition to hover to give immediate line of site? Would save having to whip the goggles off at a critical moment. Can the pix hawk do auto landings like the APM?

You mean like the Skyzone goggles? Neat idea and I look forward to getting as far as having that problem to solve! The Pixhawk can actually run the APM:Plane firmware or it can run the PX4 firmware, when running the APM:Plane firmware you get all the features of the original APM ++, as the board is much faster. I'm not sure what the true capabilities of the PX4 firmware are as it's very different to APM:Plane and will report back as soon as I've had a dabble in the configuration screens.

Surely you want a camera on the plane that tilts as the plane goes to-from VTOL. That should be pretty trivial to do with PX4 or APM software. Just a question of getting current pitch and subtracting that from your desired camera angle and then applying to ppm output to a servo.

regards
Andy

Brucey · March 27, 2015, 10:58:53 AM

How big of a prop can you fit on there? Can you sling it in the car and bring it to MD, I'd like to have a look!

iPeel · March 27, 2015, 11:51:31 AM

I thought about the option of tilting the camera Andy but certainly for the first few runs I'll be LOS only and will probably want to dabble with something elaborate after that.

Bruno, I might pack a few bits of it but doubt I'll have any time tonight to progress any more of the build to have anything like a built up airframe by tomorrow, too many batteries to charge!