[Canberrauav] Hybrid Hex cleanup

James Pattison james at auturgy.com.au
Sat May 2 23:00:17 AEST 2015


Subscale prototyping reduces the risk and cost. Much safer to figure out the transition and aerodynamic interactions with a foamy and plastic props than going straight to something that has a whole lot of kinetic energy, and metal and carbon to transfer it.

This concept needs to be tested because there are some significant challenges that need to be explored:

in forward flight the rotors will seriously mess with speed/endurance/control, not just drag but aerodynamic, gyroscopic and inertial effects, and this might be approximated to a degree from a prototype;

in vertical flight you'll have serious problems with stability running 26" props at 6S with aircraft bldc motors - it'll be sloppy. Add wet/sail area from the aircraft, and I have no confidence that the system will have the responsiveness to be controllable in a crosswind.

After testing the concept on a small system, the next step should be to build a quad in the dimensions of your design, and see if you can tune it, before trying to graft it onto an aircraft.

Going straight to a 13kg frankenplane monster is fraught with danger that is unnecessary and avoidable.

As for electric not being able to go the distance - I disagree.

Vampire is a cool name though.

Regards,

James

> On 2 May 2015, at 22:08, Jack Pittar <jpittar at bigpond.net.au> wrote:
> 
> Scaling down to 60 size means the aircraft can barely lift itself. If it was successful, what would this prove?
> Duplicating the drivetrain? We know an all electric drivetrain will not make the distance. A petrol only drivetrain means helicopter mechanics which is what we already doing, so this is no longer an alternative.
>  
>  -----Original Message-----
> From: James Pattison [mailto:james at auturgy.com.au]
> Sent: Saturday, 2 May 2015 4:11 PM
> To: Grant Morphett
> Cc: Jack Pittar; canberrauav
> Subject: Re: [Canberrauav] Hybrid Hex cleanup
> 
> I think we should start with a smaller proof of concept.
> I'm not sold on this idea at all, and need some convincing that adding so    much dead weight/drag by duplicating the drivetrain has advantages over a tilt rotor or tilt wing.
> A concept demonstrator may provide some confidence.
> 
> Regards,
> 
> James
> 
>> On 2 May 2015, at 12:26, Grant Morphett <grant at gmorph.com> wrote:
>> 
>> Are we thinking of doing a smaller prototype first with a bixler or something or just jump right into the big one?
>> 
>> Thanks, Grant.
>> 
>>> On 1 May 2015 at 18:03, Jack Pittar <jpittar at bigpond.net.au> wrote:
>>> 
>>> Ah ..yes. I forgot the speed controllers. That makes it $510.
>>> This pricing is just a quick add up of the basic parts without any close
>>> study of them.
>>> Built in spares were not considered, but would be in any purchase because
>>> you can not always get repeats of the same item a few weeks later.
>>> The receiver, telemetry, pixhawk, battery, switches, wiring and connectors,
>>> etc etc are all considered to be part of the plane.
>>> Also not included are the carbon fibre tubes or hardware to mount the motors
>>> etc.
>>> Jack.
>>> 
>>> 
>>> The list:
>>> 4 off Red Brick speed controllers, OPTO, 125 Amp, 2~7S - $37.48 each.
>>> 4 24X8" props - $26.59 each.
>>> 4 off G46-420 motors - $63.56
>>> 
>>> -----Original Message-----
>>> From: James Pattison [mailto:james at auturgy.com.au]
>>> Sent: Friday, 1 May 2015 12:58 PM
>>> To: Jack Pittar
>>> Cc: canberrauav
>>> Subject: Re: [Canberrauav] Hybrid Hex cleanup
>>> 
>>> 
>>> Are you sure on the costs?
>>> What motors/esc's have you picked (a giant quad for under $400 would be
>>> awesome!).
>>> 
>>> Regards,
>>> 
>>> James
>>> 
>>> > On 1 May 2015, at 12:03, Jack Pittar <jpittar at bigpond.net.au> wrote:
>>> >
>>> > The following is to clean up the discussions on the Hybrid Hex.
>>> > Thanks to all for your interesting discussions.
>>> > After lots of fiddling around with different physical formats, I have
>>> settled on the following for the prototype:
>>> > A 2.2 metre wingspan ARF model - the MaxiLift or Porter - will have a fore
>>> and aft boom fitted to each wing. Each boom will have motor and 25"
>>> horizontal propeller mounted on each end, making a traditional quad.
>>> > The horizontal stabilizer will be moved to the top of the vertical
>>> stabilizer for clearnce of the quad propellers.
>>> > The motor will be a standard tractor mounted 40cc petrol twin (because I
>>> already have it).
>>> > A tricycle undercarriage will be fitted to allow normal aircraft takeoffs
>>> and landings.
>>> > The intention for the prototype is to experiment with the aircraft
>>> handling in vertical and horizontal flight and in transitioning, beginning
>>> at the minimum weight of 13Kg.
>>> > The cost and size of the quadcopter parts, to make the aircraft operate as
>>> calculated for in eCalc, were a significant roadblock. This was cleared when
>>> Stephen pointed out that the quadcopter components only have to lift and
>>> maneuver. The Hobby King cost of these parts will be $360 without batteries.
>>> One 5Ah 6 cell battery ($105,0.85 Kg) is eCalc'd to bring a hovering and
>>> maneuvering time of 2 minutes or so. 5 batteries, 8 minutes.
>>> > The requrement to have all propellers stopping will be dealt with later.
>>> > With thanks particularly to Ben and Daniel, the generator concept sounds
>>> quite feasible. It would save on making a mechanical clutch mechanism at the
>>> expense of making a synchronous rectifier and power controller. Depending on
>>> conversion efficiencies, a bigger engine would probably be required if it is
>>> to allow for continuous hovering and maneuvering.
>>> > Rather than a "Hybrid Hex" I suppose it should be described as a
>>> "Quad-plane Hybrid".
>>> > A good name for it would be the "Vampire", although that name should be
>>> reserverd for whichever        aicraft we take to the OBC.
>>> > Jack.
>>> >
>> 
>> 
>> 
>> -- 
>> Thanks
>> 
>> Grant
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