One of the most important things you learn about press releases and promotion is that if you give a journalist a piece of marketing written like a news article they will print it with little to no change. This was true thirty years ago when I was working in the music industry and it is even more true now where the amount of ‘journalism’ has multiplied across the internet into clickbait headlines and engaging CGI graphics with a thinner and thinner veneer of accuracy.
If you can provide a modern journalist with a nice headline, a nice picture and something approaching a grammatically correct piece of marketing you do not have to pay for an advert as you can get it printed for free.
eVTOL figured this out years ago and the leading eVTOL developers are masters of the fine art of the internet press release.
The latest to appear is the offering from Alef Aeronautics. This is an intriguing concept of a wheeled car like vehicle that on take off rotates around the road vehicle’s longitudinal axis to present the top of the car to the airflow. The sides of the car form the wings of a biplane and the body of the car is revealed as a grid that allows the air to pass through. In effect it is a tailless biplane – box wing design as is revealed by one of their patents
This means they must have a fly by wire control system as they have no practical aerodynamic stability in all parts of the flight envelope.
Little performance data is available on the company website (https://alef.aero/) but the patent does give some interesting data:
The most intriguing metric is the peak L/D of 22. This is the ratio of lift to drag and is a measure of peak aerodynamic efficiency. For comparison, a motor glider will have a L/D similar to this aircraft. This should allow us to draw the conclusion that the peak L/D shown is not likely to be achievable.
Examining the rest of the patent the following data is also available – MTOW = 480kg, payload weight = 120kg, cruise speed = 50m/s.
Putting these values in real money: MTOW =1000lb, Payload =265lb, Cruise speed = 97knots.
First of all this is a very light aircraft. A very, very light aircraft. You can search the database of VLA (Very Light Aircraft) here: https://www.aeroexpo.online/aeronautic-manufacturer/very-light-aircraft-203.html
There are no aircraft in this category with a weight this low. One of the lightest VLA aircraft is the Pipistrel Alpha (https://www.aeroexpo.online/prod/pipistrel-doo/product-171425-740.html) this is a 1200 lb MTOW aircraft and has a peak L/D of 15 at 64 knots (https://pilotweb.aero/aircraft/flight-tests/flight-test-pipistrel-alpha-bcar-s-6305456/)
Considering that the Alef product is also a roadable aircraft that will have road wheels, tires and suspension, the idea that it could be lighter than the lightest equivalent non roadable aircraft is not credible.
Examining the dense milk crate structure that this aircraft has to push through the air their L/D projection is very optimistic. The drag coefficient of this aircraft is going to be somewhere between ‘very high’ and ‘very, very high’. And will not support a L/D of anything over 20. I would be surprised if it was greater than 5.
We can also look at some other aspects of this program. They claim they have been granted a limited Special Airworthiness Certificate. This appears to be the direct press release (https://www.prnewswire.com/news-releases/alef-becomes-the-first-car-certified-to-fly-301863749.html) There are details on the limited Special Airworthiness Certificate here: https://www.faa.gov/aircraft/air_cert/airworthiness_certification/sp_awcert/limited
On this page the following information is given “A limited category special airworthiness certificate is issued to operate surplus military aircraft that have been converted to civilian use under the following conditions:” This definition is confirmed by the federal register: https://www.ecfr.gov/current/title-14/chapter-I/subchapter-C/part-21/subpart-H/section-21.189
The company is also projecting customer deliveries in 2025. This means that the company must achieve flight and road certification in around two years.
- The Alef project has filed a patent that includes information that, to be very charitable, is excessively optimistic in terms of weight and aerodynamic performance.
- The company has issued information regarding the certification status that, on the face of it, is definitionally false. They may have been awarded a special airworthiness certificate that is limited in some other way (other than definitionally).
- They will not be delivering certified products in 2025. They will suffer from significant weight growth, a large degradation of aircraft performance and excessive complexity, excessive cost and excessive delay in their design, production, supply chain and related compliance activities.
And planning for a more credible future, some key points:
- If you are a journalist check that basic feasibility of the information you are given.
- The patent office does not check your work for credibility only for uniqueness. You will be published, wrong or right, as long as you are unique.
- Avoid putting easily refutable/physically impossible data in publicly available documentation.
- Basing a business on your own far fetched marketing rhetoric will always end in tears. (don’t believe your own B.S.)
This aircraft is a neat concept and thought experiment. If it is ever actualized it will be a terrible aircraft and car in one.