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Assen Aeronautics A1 Explorer (defunct)

A1 Explorer (defunct)
Assen Aeronautics
Miami, Florida, USA

Assen Aeronautics was created in 2015 by the founder Assen Andonov, who is originally from Bulgaria. He has had a love for aviation since he was a child and started gliding at age 15, parachuted at age 17 and piloted powered aircraft at age 18. At 23 he co-founded a company that designed and manufactured numerous types of airplanes and at 25, he started a company for business to business imaging services. Andonov has also designed two (2) airplanes and is also a commercial pilot.

A friend of mine came back from a trip to Haiti and told me about cracks on the road due to the major earthquake that hit the country back in 2010. Someone had called an ambulance and the ambulance could not reach because of a crack that measured six feet in length, "Wouldn’t it be neat to have something like a flying motorcycle, light and easy to fly for paramedics to use in these circumstances?" he said. However, I think our main audience, at first, will be sports enthusiasts or people who enjoy the thrill of riding motorcycles. —Assen Andonova

The A1 Explorer prototype project began in 2015 and Andonov decided to start with a small aircraft size because he felt this would help him successfully make and fly a functional electric vertical and take-off and landing (eVTOL) aircraft as a private enterprise, without the financial backing of outside investors. He knows that one needs to purchase materials to make the aircraft, have a team of engineers to design the aircraft but in addition; one has to pay the engineers for their work while they are gaining experience on the job.

Initially, Andonov was considering making a road worthy and air worthy vehicle but to keep things less complicated and less costly, he’s settled on a less complex VTOL aircraft with skid landing gear. The first parts were made in 2016 when the working title for the prototype land/air vehicle was the Wasp T1. Then later, the Wasp T1 name was changed to the A1 Explorer when the land capability was eliminated and the aircraft was designed to resemble a flying motorcycle. (His second eVTOL aircraft is called the A2 Avenger which is detailed on the "eVTOL News" website here.)

These are some of the reasons for creating a small and simplified aircraft, instead of a large complex VTOL machine. In addition, because it’s a new aircraft, it would to be difficult as a small business to create a larger vehicle that would meet the strict FAA commercial certification rules. By making it an ultralight aircraft, they can offer it for sale in the US under the current regulations right away and to many more people and in many more countries because of the relaxed airworthiness and pilot certification requirements for this category of vehicles.

The A1 Explorer (a ducted fan tri-copter or a flying bike tri-copter) is a battery operated electric Vertical Take-Off and Landing (VTOL) personal air vehicle made for recreation and sports. The aircraft was designed to fit into a normal parking space and could easily land in a parking lot on the top floor of a parking garage.

The first flight of the A1 Explorer prototype took place on September 8, 2018 in Miami, Florida, USA. It was a remotely piloted flight, was untethered and flew for a short period of time. Just like all VTOLs, the aircraft is sensitive to the weight of the pilot and one will have to expect a reduced range with pilots over 200 lbs (91 kg). A lighter pilot will be able to fly longer than the stated full range of the aircraft. Just like all aircraft, you can fly fast or far but not fast and far.

Assen Aeronautics is incorporating many safety features to improve the safety of flight before they offer their aircraft for sale. Using ducted propellers provides more efficiency, better lift and provides safety for people around the aircraft. They are also working on being able to predict the service life of the electric motors and having the aircraft notify the pilot when an electric motor starts to fail. How this works is when sensors discover the very first signs of trouble with an electric motor, the software will signal the pilot and the pilot will have sufficient time to land the aircraft before a catastrophic failure will occur. If the pilot doesn’t land the aircraft, the aircraft will land the vehicle for you. This safety feature is tied in with the semi-autonomous capability of the aircraft and will have an optional ballistic recovery system as a backup.

The company is also limiting the aircraft’s speed to about 55 mph (88 km/h) for safety reasons for the pilot and also because birds can typically fly away from aircraft traveling at lower speeds. This reduces the chance of any birds entering into the ducted propellers. The blades have been designed to withstand the damage of flying close to the ground and will have an initial service life of 200 hours. As the aircraft enter service and more data becomes available the company expects that time limit to increase.

A remark heard often, is why doesn't the aircraft have a second propeller in the ducts for redundancy? Assen Andonov explains that it requires a lot of air to go down through these ducts for the aircraft to fly and if something gets ingested in the duct, whatever goes into the top, will go through and damage both propellers inside. With the A1 Explorer, the risk is lower than a typical helicopter where the helicopter tail rotor is exposed and can strike the ground during maneuvering.

The A1 Explorer flying bike has a length of 10 ft (3 m) and a width of 8 ft, 10 in (2 m), weighing 114 lbs (52 kg) without the batteries and supports a 220 lbs (100 kg payload). The battery drive powers two (2) forward and one (1) aft electric motors for the ducted propellers which are situated around the pilot’s saddle. The propellers are ducted to provide a safe, quiet and efficient aircraft. The batteries can provide up to 20 minutes of flight time and the flight altitude is limited to 150 ft above the ground up to 4,000 ft (1,219) m density altitude, while the max speed is 63 mph (101 km/h).

As much as people are excited, I have to tell you that, from what I see, there are very few people that are older than 30, today, who will be comfortable flying in commercial vehicles like this. And we’re talking about piloted air vehicles. Autonomous vehicles? I believe this is the next generation mode of transport.

So what we’re trying to do is engage the youth into flying, by basically making Star Wars a reality. Because kids can see themselves instantly, fly through the forest in this vehicle and when they are 20 or 25 this will be absolutely normal for them.

—Assen Andonova, Ep. 2 // Assen Aeronautics with Founder Assen Andonova, The Aerial Mobility Podcast, by TransportUP, Aug. 19, 2018

Piloting skills needed? According to Andonov, one won’t need advanced piloting skills to fly it because it’s intended to be very easy and intuitive. Designed for daylight flying only, outside of controlled air space and for recreational use, it would be similar to a kid flying a drone, he said. But one does need the training of good judgment such as, where not to go (near airports, over people’s properties, over crowds, over any type of public or private event, avoiding hanging wires, trees and buildings, etc.), when not to go (don’t fly at night, in bad weather or when impaired), as well as how fast one should fly, and learn how to choose a good landing spot.

Once a person gets to an advanced level of piloting, the company predicts they will be able to fly the aircraft aggressively. They see their first customers coming from those who are motorcyclists, which is why the controls are the similar to a motorcycle. If you are comfortable with a motorcycle, it should have about the same feeling as riding a motorcycle.

It will have by fly-by-wire controls which will limit how one can fly the aircraft in terms of limitations on speed and attitude, not allowing you to exceed roll and pitch limits. Despite that they would recommend their first customers to have at least a sport pilots license, even though it’s a FAR 103 aircraft (an ultralight aircraft) and doesn’t require it.

Currently, the pilot will have control of the navigation and routing with features like preprogramming a route and in-flight rerouting coming soon. Ultimately, they want the capability of calling their vehicle (maybe it is sitting on top of a garage and charging) from an app, and have it fly to your front door, you plug in your destination into the app and the bike it flies autonomously for you.

They have intended this aircraft for many different applications but the obvious ones are leisure and racing. Now is the time to introduce it because people who are around the age of 15 today, will be 25 or slightly older, in 10 years time and at that point, they will most likely be in the position to buy and use these personal VTOL aircraft. Also, in ten years time, it is hoped that social acceptance will have been built up with the general public as well so these vehicles will have become an integral part of our lives.

This is part of Assen’s marketing strategy to offer a small VTOL aircraft for leisure and extreme sport as a “flying car” which they hope would more likely be naturally accepted into people’s lives rather than larger urban aircraft. This strategy also is hoped to reduce the skepticism of urban and rural VTOL aircraft. Larger urban VTOL aircraft will be created in the future.

Assen Aeronautics sees their company as the leader of the 2020’s and see themselves as a major player in the world of transportation with an established presence on all continents. They want to have maintenance, sales, and support centers worldwide. They know it’s a lofty plan but they want to aim high rather than be brought down by complicated government aviation regulations or a lack of vision.

The working prototype took two and half years to complete, and has been tested at the company’s south Florida facilities. The company attended EAA AirVenture Oshkosh (Wisconsin, USA) in 2018 and 2019, and is planning to organize racing events to help get public approval of urban VTOL aircraft.


  • Aircraft type: eVTOL prototype
  • Capacity: 1 passenger
  • Maximum Speed: 63 mph (54.74 kn, 101 km/h)
  • Ceiling at gross weight: 4,000 ft (1,219 m) at density altitude.
  • Length: 10 ft (3 m)
  • Width: 8 ft, 10 in (2.7 m)
  • Weight as shown: 114 lbs (51.7 kg)
  • Pilot weight: 200 lbs (91 kg) or less for optimal performance
  • Maximum Gross weight: 463 lbs (210 kg)
  • Propulsion system: Electric motors and ducted fans
  • Power: 57 kW
  • Maximum Continuous Thrust: 600 lbs (272.1 kg)
  • Maximum Thrust 2 minute limit: 720 lbs (326.6 kg)
  • Maximum sustained bank angle: 40 degrees
  • Maximum bank angle for 10 sec: 50 degrees
  • Battery Capacity: 12.8 kWh
  • Landing gear: Skids
  • Safety features: Optional emergency parachute. Low maximum speed for safety for the pilot and also, birds can fly away from aircraft at that speed. The computer will be able to detect end-of-service life for each motor and will alert pilot to land before a motor fails. If the pilot doesn't land after the alert, the semi-autonomous mode will land the aircraft itself.