Quadrotor Biplane VTOL + Plans

[NickRehm]

Hi all,

I wanted to share my latest VTOL creation: a quadrotor biplane.

This type of vehicle configuration offers unique advantages: a small footprint, vertical flight capabilities, high payload capacity, and long endurance forward flight. Stability in hover is achieved similarly to a conventional quadrotor through RPM of the rotors. In forward flight, control can be maintained through rotor RPM inducing moments on the vehicle alone, though augmenting this with additional control surfaces provides additional redundancy.

I have mine setup in my flight controller to "swap" the rudder and aileron for forward flight, and engage the stabilized elevons. Swapping the controls allows it to fly identically to an airplane in forward flight rather than like a quad pitched over 90 degrees. Personal preference
The above video is the first flight in which I performed a full transition into airplane mode (and was filming myself, sorry for some of the bad shots!). It flies very much like a wing that is on rails, since it is stabilized in forward flight as well. In the future I would like to compare flight times in hover vs. forward flight, and potentially try to modify it for extremely high forward flight speed. Stay tuned!

The build is dollar tree foamboard with a kfm-2 airfoil, and 3mm carbon spars to reinforce the wings. The fuselage is 3D printed and houses my custom flight control board, ESCs, and battery. Its a bit of a tight fit, but the aerodynamic housing really helps in forward flight.

I've attached plans (full sheet + a4 paper printable) + .stl files for the motor mounts (standard 16mmx19mm motor mount) and fuselage pieces. The fuselage can either be printed from my .stl files (print two of each and glue together with 3mm carbon spar to reinforce them--to fit on smaller print beds), or built up from foam--the fuselage profile is included in the plans.



Cheers!

 

[NickRehm]

Check out this awesome video by a buddy of mine who also specializes in quadrotor biplane platforms:

 

[Allister779]

This looks awesome! You mentioned you are using your own board, are you also using your own software or are you using Ardpilot/Px4, etc?

 

[NickRehm]

This looks awesome! You mentioned you are using your own board, are you also using your own software or are you using Ardpilot/Px4, etc?

Yes, my own software as well. You could fly this vehicle with any flight control software available--ardupilot, betaflight, etc. as it is just a simple quad configuration. I'm not sure how easy it would be to implement the stabilized control surfaces or yaw/aileron control swapping, but I'm sure it could be done!

 

[NickRehm]

Quick update video on this vehicle. Little mishap while flight testing, but watch for a teaser on the much larger version coming soon:

 

["Corpse"]

Quick update video on this vehicle. Little mishap while flight testing, but watch for a teaser on the much larger version coming soon:

Dang this thing is cool! You always come out with amazing things, Like that F-35.

 

[L Edge]

Have you tried hover/transition/land in any wind conditions? That is the real test especially for hover/landing.

 

[NickRehm]

Have you tried hover/transition/land in any wind conditions? That is the real test especially for hover/landing.

Good point, yea wind is a bit more of a challenge with the extra cross sectional area. It usually settles facing into the wind fairly easily at a 15-20 degree angle

 

[FL_Engineer]

This is some strange and wonderful stuff. I subbed your channel after the promo from xjet.

 

[NickRehm]

Quick update on a larger quad biplane project... we just finished up preliminary design review and I'm hoping to begin the build soon (though university resources are a bit strained at the moment, and deadlines are a bit unrealistic. Project may end up being scrapped...)

 

[PsyBorg]

Quick update on a larger quad biplane project... we just finished up preliminary design review and I'm hoping to begin the build soon (though university resources are a bit strained at the moment, and deadlines are a bit unrealistic. Project may end up being scrapped...)

Is there a technical purpose for this or is it just a unique one off project? Im not seeing it as something the masses will flock to if a commercial endeavor is the end goal. Most suburban ambulance services are volunteer with minimal budgets and grants. I dont see them spending money on part 107 certifications or more so a civil service certification to use something like this let alone the added insurances that would be mandatory. Inner city use is a non starter for sure.

Drone delivery in any fashion or reason other then in 3rd world countries where separation and isolation is a big factor is a fail of epic proportions with the tech as it stands. We wont even add in the Darwinian antics of silly humanz hoping for it to happen. Half the knuckle heads today cant even pull their pants up or NOT walk in the middle of a street let alone be trusted anywhere near flying objects... Just sayin.

 

[NickRehm]

Check out the challenge website: https://www.firstresponderuaschallenge.org/

The end goal is for groups to develop low-cost, high endurance VTOL platforms that can carry a 10 lb LTE communications payload. Basically to be deployed in remote areas and give communications coverage for search and rescue, disaster relief, etc. The key is low-cost. Existing systems cost upwards of $30-40k. Ours is less than $8k.
The National Institute of Standards and Technology (NIST) is funding & organizing the challenge and we're going along for the ride. Not sure of their end-goal intentions in terms of commercializing a solution, but I'm sure they're working on something themselves and are looking for outside ideas to implement too. They've done all the consumer research, and apparently there's a real demand for a system like this. The price per endurance/payload metric has always been too high for first responder groups and they want to drive that metric down it seems.

 

[JasonK]

will your 'end cost' be similar to your development parts cost?

Obviously your not paying back any R&D costs, doing serious levels of stress testing (which would impart further costs), nor covering the manufacturing facilities (it appears you already have access to a fairly good set of manufacturing systems).

Just curous on the expected impact of 'commercializing' something like this.

 

[NickRehm]

will your 'end cost' be similar to your development parts cost?

Total cost is simply price of all components and raw materials--so no R&D or manufacturing labor costs. I'm not too interested in the idea of mass producing our system either. I see this whole thing more of as a "Here's the capabilities you can get with off-the-shelf hobby components" type of thing. Sort of a slap in the face to all the horribly overpriced startup drone companies
Manufacturing a *good* airframe won't cost more than $1k for nearly any system at this scale. Mass production makes it cheaper still. Then just throw on your favorite avionics package and T-motor power system and you're set.

 

[JasonK]

Total cost is simply price of all components and raw materials--so no R&D or manufacturing labor costs. I'm not too interested in the idea of mass producing our system either. I see this whole thing more of as a "Here's the capabilities you can get with off-the-shelf hobby components" type of thing. Sort of a slap in the face to all the horribly overpriced startup drone companies
Manufacturing a *good* airframe won't cost more than $1k for nearly any system at this scale. Mass production makes it cheaper still. Then just throw on your favorite avionics package and T-motor power system and you're set.

I could be wrong... But I suspect that R&D, various licenses (aka FCC for the transmitter bits), and 'safety certification' costs are a big deal to commercialize stuff like this. Also, remember, when demand is low, the per item profit has to be higher to account for all of the edge cases.

 

[PsyBorg]

Check out the challenge website: https://www.firstresponderuaschallenge.org/

The end goal is for groups to develop low-cost, high endurance VTOL platforms that can carry a 10 lb LTE communications payload. Basically to be deployed in remote areas and give communications coverage for search and rescue, disaster relief, etc. The key is low-cost. Existing systems cost upwards of $30-40k. Ours is less than $8k.
The National Institute of Standards and Technology (NIST) is funding & organizing the challenge and we're going along for the ride. Not sure of their end-goal intentions in terms of commercializing a solution, but I'm sure they're working on something themselves and are looking for outside ideas to implement too. They've done all the consumer research, and apparently there's a real demand for a system like this. The price per endurance/payload metric has always been too high for first responder groups and they want to drive that metric down it seems.

If this is the case I would have gone Tilt rotor fixed wing VTOL for the pay load and efficiency. That would give STO capabilities so it could be launched anywhere with a ~ 20 foot egress. Than the payload could be dropped with little detrimental effects opposed to a multirotor. I would assume GPS navigation for guidance with maybe an RFI target indicator for the payload drop vs trying to land with GPS auto pilot. Too much power is lost in drag on a quad system as well as super gimped payload capacity totally killing effective range. It could also be capable of a low power loiter so the Com system would have better range if activated on board and not delivered. Maybe even solar augmented power system to extend loiter longer.

 

[NickRehm]

I could be wrong... But I suspect that R&D, various licenses (aka FCC for the transmitter bits), and 'safety certification' costs are a big deal to commercialize stuff like this. Also, remember, when demand is low, the per item profit has to be higher to account for all of the edge cases.

Like I said, it's all hobby grade components under 55lbs and all FCC compliant. You could build one yourself if you wanted to

 

[JasonK]

Like I said, it's all hobby grade components under 55lbs and all FCC compliant. You could build one yourself if you wanted to

I have no doubts in my ability to build something like that. When you put something together and sell it, there is extra stuff that has to be done then doing it yourself. Your VTX is FCC registered? (I don't know of many that are)

 

[NickRehm]

Started prototyping the variable pitch hub for the big boy

 

[JasonK]

@Rcjetflyer2 - saw video yesterday, interesting mechanistic.