The FAA’s initial vertiport design brief shows some marked differences from conventional helipad design standards, according to Toby Enzerink, Drone Consultant at AirHub
Vertiport designs based upon ICAO Annex 14 (heliports) differ widely from the recently published draft for vertiports issued by the US Federal Aviation Administration (FAA) ( https://www.faa.gov/airports/engineering/engineering_briefs/drafts/media/eb-105-vertiport-design-industry-draft.pdf).
Using heliport standards to analyse the (potential) impact of designing vertiport take-off and landing areas – and based on the characteristics of the Lilium Jet eVTOL with a wingspan of 13.9 meters and a maximum take-off weight (MTOW) of, 3175 kg – the total area required for eVTOL operations is more than doubled than that required for conventional helicopter operations: 773 m2 relative to 1739 m2.
This is the first draft of the FAA vertiport design engineering brief; the FAA will hold a virtual Industry Day meeting on the draft EB 105 on March 29, 2022 at 11:00 am ET to discuss the critical aspects. The EB105 specifies more than just the dimensions, it includes standards for charging infrastructure and safety considerations (e.g. fire fighting).
ICAO Annex 14 Volume II design
The results of this initial analysis shows a total dimension for the take-off and landing spot of 772.8 square meters. The total dimension includes a final approach and take-off area (FATO) (including a Touchdown and lift-off area (TLOF)) and safety area, which are required by law for heliports. Therefore, the following applies to the Lilium Jet (based on performance class 2 or 3 helicopters):
FATO = 0,83 ∗ wingspan = 0,83 ∗ 13,9 = 11,5 𝑚
Safety area = 0,25 ∗ wingspan = 0,25 ∗ 13,9 = 3,5 𝑚
FATO + safety area = 11,5 + 3,5 = 15,0 → at least 2 ∗ wingspan =27,8 𝑚
Total area (surface) = 27,8 ∗ 27,8 = 772,8 𝑚2
The FAA also distinguishes the TLOF, FATO and safety area. The dimensions for these areas are based on the controlling dimensions (CD) which is the longest distance between the two outermost opposite points on the eVTOL. For the fixed-wing Lilium Jet, this is equal to the wingspan. For the dimensions, the following applies:
TLOF = 1CD = 13,9 m
FATO = 2CD = 2 * 13,9 = 27,8 m
Safety Area = 2 * ½CD (added to edge of FATO) = 2 * 6,95 = 13,9 m
Total = 3CD = 3 * 13,9 = 41,7 m
Total area (Surface) = 41,7 * 41,7 = 1739 m2