StopRotor Prototype

20kg MTOW | Small UAV category

The SR800 StopRotor prototype has been designed as a modular test bed to easily interchange different wing profiles, rotor systems and engine options.

Helicopter hover and fixed wing efficiency will be improved with a custom rotorwing design. An ‘off the shelf’ helicopter has been used in the current and previous aircraft prototypes. The test program will determine optimum rotorwing design and wing profiles to optimise overall performance.

StopRotor Program Objectives

The prime objective is to demonstrate controlled, routine starting and stopping of the rotorwing in-flight enabling transition between fixed and rotary wing flight in a single aircraft.

The air vehicle performance objectives are as follows:

  • Increased aircraft hover efficiency: Retain and improve Helicopter hover efficiency with minimum compromise to achieve range and endurance targets.
  • Increased aircraft cruise efficiency: Lift to drag 10:1 or greater (wind tunnel demonstrates 17:1 in clean configuration)
  • Useful load & payload fraction (40% and 10-12% of gross weight respectively)
  • Increased aircraft sustained flight speeds: High speed, long endurance, long range (relative to MTOW State of the art)

“To simultaneously satisfy these goals / capabilities on a single air vehicle is essential, as they exemplify the ability to improve VTOL flight speeds while also improving (or at minimum, retaining) the ability to do useful work.” DARPA 2013

StopRotor Small UAS Specifications

  • Max Takeoff Weight: 20 – 25kg
  • Length: 3m
  • Rotor Span: 1.74m
  • Canard Wing Span: 1.3m
  • Rear Wing Span: 2m
  • Fixed wing cruise speed target: 60kts**
  • Endurance target: 12 – 15 hours**
  • Payload maximum 5kg

** performance metrics verified on completion of current testing activity.

Development Updates

RMIT SR800 Initial Wind Tunnel Test Data

Wind tunnel testing has been completed in both fixed and rotary wing configurations. The tests were run to over 110kph in fixed wing mode and up to 70kph in rotary wing mode. Early results include:

Lift to drag ratio 17:1 clean configuration.

Designated cruise speed will require approximately 3kg of thrust.

This demonstrates the SR800 is highly efficient and on target to achieve significant range and endurance. Some L/D ratios for comparison include: a helicopter 4:1, a Cessna 10:1, a Boeing 747 17.1, an Albatross (sea bird) 20:1 and a sailplane 40-60:1.

The rotary wing while stationary, acting as fixed wing, produced a significant contribution to overall lift.

Wind tunnel tests demonstrated functional auto-rotation capability.

The SR800 demonstrated its designed vertical take off thrust at less than 50% of the rated power of the engine.

Target Market : Commercial | Government | Defence

StopRotor SR 600 Rotary
StopRotor SR 600 Fixed

Deploy & retrieve where you need to

No nets, no runways, no catapult!

The utility of VTOL helicopter performance and control enables operations in diverse environmental conditions from confined (wooded, urban or maritime) and unprepared areas.

Maximum capability

Small UAS category

Fixed wing cruise will provide long range, long endurance requirements for sustained data acquisition.

Commercial & Government Applications

Coastal surveillance | Public safety | Infrastructure monitoring including pipeline & power line management | Environmental monitoring | Agriculture management | Disaster relief operations | Search operations | Rural fire spotting and management | Payload including medical delivery

Military Applications

Intelligence, Surveillance & Reconnaissance | Payload including medical delivery

Industry Needs

Does the StopRotor aircraft concept interest you?

We are interested in hearing opinions from industry & operators.

As an operator what do you and/or your customers want or need solved?

What applications would you use a StopRotor aircraft for?

What payload requirements do you need or desire?

Would you purchase, lease or use an an approved operator to complete your work?

Please submit your information and/or questions.

13 + 9 =

Commercial Objectives


  • Of both operators and property


  • Enable consistent performance and serviceability in the field. Sustained operations deliver value ROI to the owner/operator/leasee.
  • Training, operational service & support

Easy of operation

  • Largely autonomous operation by crews of two persons
  • Ease of transportation & assembly


  • Systems must meet regulatory requirements
  • Provision for BVLOS operations
  • Operate at or under small RPAS category (20-25kg*) enabling ease of adoption by UAV operators worldwide. * subject to country of operation requirements.


  • Diverse environmental operating conditions,
  • Minimal weather delays

Low Cost

  • Affordable, competitive price
  • Extend operations: Range & endurance, beyond visual line of sight (BVLOS)
  • Sustained data acquisition