1. Introduction

2. Status of Electric Vertical Take-Off and LANDING

3. Technology Roadmapping

3.1. Introduction to Technology Roadmapping

Technology roadmapping is a versatile tool widely used in industry for strategic planning. It visually maps the connections between evolving markets, products, and technologies over time[8]. It offers a structured approach to explore and communicate linkages between technology resources, organizational goals, and changing environments[9].Researchers define technology roadmaps as consensus visions of future technology landscapes, guiding the identification, evaluation, and selection of strategic alternatives to achieve specific objectives[9,10]. They address key questions like: “Where are we going?” “Where are we now?” and “How can we get there?”[11].

Technology roadmaps can be tailored to different levels, from component-level to entire sectors or fields of science[12]. They typically consist of three layers—technology, product, and market—along with a time frame.

Figure 2. One typically technology roadmap with three layers.

Figure 2. One typically technology roadmap with three layers.

3.2. Policy-Technology Roadmap

Many technological roadmap studies analyze market, product, and technology dimensions, yet few integrate policy into the framework. In regions where policy holds significant sway, understanding how policy interventions impact technology evolution via market and product strategies is crucial. Hence, the emergence of a Policy-Technology Roadmap (P-TRM), which incorporates policy tools, constructing a new framework to analyze policy effects on different stages of industrial development[13].

Policy tools can be categorized into three types: supply-side, environmental, and demand-side. Each type influences the market, product, and technology differently throughout technological and industrial evolution.

Table 1. Types of policy tools.

Table 1. Types of policy tools.

Type of policy tools	example	effect
Demand-side policy	Public procurement, price subsidies.	Stabilize the market environment for innovation, fostering confidence and stimulating technology research and development.
Environmental policy	Standard design, goal planning.	Shape product development by setting performance norms, encouraging innovation, and facilitating industry transitions
Supply-side policy	technology infrastructure, technology input	Support enterprise research and development, encouraging investment and effective resource allocation

In early industrial stages, supply-side policies promote scientific research completion and technology application. Demand-side policies focus on transforming technology into marketable products. Environmental policies play a consistent role throughout the innovation cycle, impacting each stage of development.[13].

In this paper, we will utilize Policy-Technology Roadmap model to construct the technology roadmap for eVTOL.

4. Main layers of the Technology Roadmap

4.2. Product

Based on the division into four stages: the research and validation stage, early commercialization stage, rapid commercialization stage, and mature commercialization stage, this section will make predictions regarding the main performance of eVTOL at each stage. Since it’s not possible to accurately predict the specific parameters and performance of future eVTOL products, this section will combine existing eVTOL-related technologies and apply research reports from leading companies in the industry to roughly describe the functions that eVTOL can achieve at each stage from a perspective focused on product functionality implementation[15].

Table 3. Predicted Development of eVTOL Products.

Table 3. Predicted Development of eVTOL Products.

	Research and Validation Stage	Early commercialization Stage	Rapid Commercialization Stage	Mature Commercialization Stage
Driving mode	Autonomous driving technology awaits validation.	Requiring visual flight conducted by professional pilots in collaboration with assisted driving systems.	The system is responsible for most flight missions, equipped with professional pilots for manual control in emergency situations.	Passenger eVTOL achieve full autonomous flight, overseen remotely by a central control system, removing the requirement for onsite professional pilots.
Performance	Prototypes need to be explored through continuous experimentation and trial applications	The ideal performance parameters include a range of 150-200 kilometers, a cruising speed of 200-250 kilometers per hour, and a capacity of 4-5 passengers.	The emergence of second and third-generation commercial eVTOL products, and the larger size of eVTOL	A trend towards personalized design, with a variety of eVTOL designed and produced for different speeds, ranges, and appearances
Air traffic control	\	Airspace and air traffic control systems have been adapted for low-altitude eVTOL flights, establishing fixed routes. Pre-approval from relevant authorities is required for flight missions.	Airspace management and air traffic control policies are becoming more flexible, with increased automation and shorter flight notification times.	The air traffic management system will be highly efficient, allowing airspace resources to be allocated on demand.
Infrastructure	\	Landing and takeoff points are set up near traditional urban transport hubs.	Start spreading to urban commercial and residential centers and expanding into suburban areas.	eVTOL landing and takeoff points are integrated into urban planning.

4.3. Market

In this section, the article will focus on describing the application scenarios of eVTOL, the operators of eVTOL operations, and the target users across different stages. This will help depict the market situation for eVTOL applications at various stages from three dimensions: target users,application scenarios, and eVTOL operators.

Due to the research and validation stage, eVTOL have not yet entered commercialization. The products are still in the prototype phase, and application standards and regulations are yet to be established. This section will not delve into the market situation during this stage.

1). Target users

In analyzing target users at different stages, we can utilize the Diffusion of Innovations theory, including frameworks like the Technology Adoption Life Cycle (TALC). This theory explains how new ideas and technology spread and at what rate. The TALC model categorizes consumers based on their risk sensitivity into innovators, early adopters, early majority, late majority, and laggards. Each group has distinct needs, product criteria, and reactions to innovations, requiring tailored marketing strategies[16]. As shown in Figure 3, with successive adoption by consumer groups (blue), the technology’s market share (yellow S-curve) will eventually saturate.

It is important to note that in the analysis below, the target users in the latter stage often encompass the user groups from the previous stage, and the users at each stage are not simply

Table 4. Users in each stage.

Table 4. Users in each stage.

Stage	Consumer Groups	New Users	Characteristics
Research and Validation	Innovators	Technology pioneers, research institutions, aviation enthusiasts	-Interested in emerging technologies and new aircraft -Capable of investing significant resources into research and experimentation -Participate in research and testing processes
Early Commercialization	Early Adopters	Middle-income travelers, large corporations, affluent private users, individuals in need of air medical and tourism services	-Willing to try new products but more cautious compared to Innovators -Often have substantial incomes
Rapid Commercialization	Early Majority	Ordinary consumers, urban residents, business travelers	-Majority of consumers -Wait for evidence of reliability and effectiveness -Willing to pay reasonable prices -Concerned about convenience and practicality
Mature Commercialization	Late Majority and Laggards	Suburban users, conservative individuals	-Cautious about new technologies

It is worth noting that with the advancement of eVTOL underlying technology and the reduction of production costs, private eVTOL will no longer be exclusive to high-income groups. The middle class may become important users of private eVTOL, similar to the current automobile market. Meanwhile, high-income individuals will focus more on personalized aviation solutions and be willing to invest in high-end personal air transportation as one of their routine travel modes.

Additionally, in the Technology Adoption Life Cycle, there exists a Chasm, which lies between early and mainstream markets[17]. Crossing this chasm is equally important for eVTOL, and the issues that eVTOL may encounter regarding this chasm will be analyzed separately in Section 6.2.

2). Application scenarios

In the early commercialization stage, eVTOL serve primarily in short-distance passenger flights, business charters, medical transfers, and sightseeing tours, akin to helicopter services. Notably, eVTOL offer advantages like lower costs, improved safety, passenger comfort, and reduced noise levels compared to helicopters.In the rapid commercialization stage, technological advancements drive market expansion, enabling larger passenger capacities and introducing shared ownership models like “air taxis” and “air buses.”In the mature commercialization stage, the eVTOL market grows substantially, with small-scale eVTOL becoming common in private ownership. Personal eVTOL are widely adopted for individual commuting, akin to the automobile market today.

3). eVTOL operation

In the early commercialization stage, eVTOL are mainly owned by enterprises and operated by professional pilots organized by eVTOL operators through leasing and other arrangements. A few high-income users may own private eVTOL. In the rapid commercialization stage, eVTOL ownership sharing becomes more common, led by operators. “Air taxis” and “air buses” emerge, reducing ownership and usage costs. Moving into the mature commercialization stage, alongside operator sharing, private eVTOL become prominent. Operators achieve cost-efficient, automated operations by remotely monitoring their fleet, marking a shift towards personalized and efficient air transportation services for both commercial and private users.

5. The Construction of the Technology Roadmap

6. Further Analysis of the TRM

6.1. Analysis by DEMATEL

1). Brief introduction to DEMATEL

Decision-making Trial and Evaluation Laboratory (DEMATEL) is a systematic analysis method that utilizes graph theory and matrix tools to interpret problems. By examining the logical relationships and direct impact matrices among various elements within a system, Dematel can calculate the influence and influenced degrees of each element on others[19].

The following are the general steps of DEMATEL[19,20].

Step 1: Generate the group direct-influence matrix (also called “relationship matrix”) Z based on the relationships between the elements.

Step 2: Normalize the group direct-influence matrix to obtain the normalized direct-influence matrix X

Step 3: Calculate the total-influence matrix T

$$T=X+X^2+X^3+...+X^h=X{(I-X)}^{-1},h\to \infty$$

(6.1)

Step 4: According to the the total-influence matrix T, calculate the effect degree (r) and cause degree (c), representing the sum of the rows and the sum of the columns from the total-influence matrix T, then calculate Prominence (r+c) and Relation (r-c). For r and c:

$$r={\left[r_i\right]}_{n\times 1}={\left[{\sum }_{j=1}^n{t}_{ij}\right]}_{n\times 1},i=\mathrm{1,2}...,n$$

(6.2)

$$c={\left[c_i\right]}_{n\times 1}^{\prime }={\left[{\sum }_{j=1}^n{t}_{ij}\right]}_{n\times 1}^{\prime },j=\mathrm{1,2}...,n$$

(6.3)

Step 5: Normalize the Prominence and calculate the weight of each element.

Step 6: Represent the relationship between Prominence and Relation through graphs, namely the Influential Relation Map (IRM).

Step 7: Analyze specific problems accordingly.

2). DEMATEL for roadmap of eVTOL

For each node in the technology roadmap, labeling is applied. The nodes of the Product layer and Technology layer at each stage are considered as a whole. The nodes within each layer are numbered from left to right, except for the nodes in the Policy layer, which are numbered from top to bottom. For example, the first node of the Market-Operation layer is labeled as M11, the third node of the Market-Scenarios layer is labeled as M23, the second node of the Product layer is labeled as P2, and the fourth node of the Technology layer is labeled as T4. Regarding the Policy layer, due to the numerous connections from the nodes of Planning and Policy Guidance and Market Access and Regulation, in order to appropriately reduce the complexity of the model, these nodes are excluded from the DEMATEL processing in this instance. Thus, Financial Support and Incentives are labeled as G2, and Infrastructure Development is labeled as G3. The labeling relationship is as shown in Figure 6.

For the weights between nodes, due to the absence of specific quantitative relationships in the existing eVTOL technology roadmap, and the objective difficulty in confirming such quantitative relationships at present, all weights between nodes in this section are equally set to 1. This simplifies the model, reduces the complexity of data collection and analysis, while still providing a relational analysis framework, serving as a reasonable compromise solution.

The group direct-influence matrix (relationship matrix) Z (18x18):

	M11	M12	M13	M21	M22	M23	P1	P2	P3	P4	T1	T2	T3	T4	G1	G2	G3	G4
M11		1			1				1
M12			1							1
M13
M21					1
M22						1
M23
P1								1
P2	1			1					1
P3		1			1					1
P4			1			1
T1								1				1
T2								1	1				1
T3									1	1				1
T4										1
G1											1	1
G2												1	1
G3									1	1
G4				1	1

In each row, the weight number represents the strength of influence of the element in that row on the element in the column where the number is located. A weight of 0 (not displayed in the matrix) indicates that the element in the row has no influence on the element in the corresponding column.

By normalizing the group direct-influence matrix, we obtain the normalized direct-influence matrix X, and after performing calculations$T=X{(I-X)}^{-1}$, ultimately derive the total-influence matrix T:

	M11	M12	M13	M21	M22	M23	P1	P2	P3	P4	T1	T2	T3	T4	G1	G2	G3	G4
M11		0.444	0.235		0.444	0.235			0.333	0.259
M12			0.444			0.111				0.333
M13
M21					0.333	0.111
M22						0.333
M23
P1	0.111	0.086	0.055	0.111	0.123	0.067		0.333	0.148	0.078
P2	0.333	0.259	0.165	0.333	0.370	0.202			0.444	0.235
P3		0.333	0.259		0.333	0.259				0.444
P4			0.333			0.333
T1	0.148	0.165	0.128	0.148	0.214	0.144		0.444	0.346	0.219		0.333	0.111	0.037
T2	0.111	0.235	0.219	0.111	0.272	0.232		0.333	0.593	0.424			0.333	0.111
T3		0.111	0.235		0.111	0.235			0.333	0.593				0.333
T4			0.111			0.111				0.333
G1	0.086	0.133	0.116	0.086	0.162	0.125		0.259	0.313	0.214	0.333	0.444	0.148	0.049
G2	0.037	0.115	0.151	0.037	0.128	0.155		0.111	0.309	0.339		0.333	0.444	0.148
G3		0.111	0.198		0.111	0.198			0.333	0.481
G4				0.333	0.444	0.148

Calculate the effect degree (r), cause degree (c), prominence (r+c), relation (r-c) and weight from the total-influence matrix T.

Table 5. DEMATEL calculates indicators.

Table 5. DEMATEL calculates indicators.

	Effect degree (r)	Cause degree (c)	Prominence (r+c)	Relation (r-c)	Weight
M11	1.951	0.827	2.778	1.123	0.057
M12	0.889	1.993	2.882	-1.104	0.059
M13	0.000	2.649	2.649	-2.649	0.054
M21	0.444	1.160	1.605	-0.716	0.033
M22	0.333	3.047	3.380	-2.713	0.069
M23	0.000	3.000	3.000	-3.000	0.061
P1	1.114	0.000	1.114	1.114	0.023
P2	2.342	1.481	3.823	0.860	0.078
P3	1.630	3.152	4.782	-1.523	0.098
P4	0.667	3.954	4.620	-3.287	0.095
T1	2.439	0.333	2.772	2.105	0.057
T2	2.974	1.111	4.085	1.863	0.084
T3	1.951	1.037	2.988	0.914	0.061
T4	0.556	0.679	1.235	-0.123	0.025
G1	2.471	0.000	2.471	2.471	0.051
G2	2.308	0.000	2.308	2.308	0.047
G3	1.432	0.000	1.432	1.432	0.029
G4	0.926	0.000	0.926	0.926	0.019

The Bar chart reflecting the weights of each element:

It is easy to see that the weights of P3, P4, T2, and P2 are greater than 7%, indicating that these nodes representing products or technologies deserve attention.

The Influential relation map (IRM):

From this figure, decision makers can visually discern complex causal relationships among factors, spotlighting valuable insights for decision-making.

Quadrant I factors, identified as core factors or intertwined givers, hold high prominence and relation. These critical nodes include technology and product nodes in the second stage, T2, P2, T3, T1, and M11.Quadrant II factors, termed driving factors or autonomous givers, exhibit low prominence but high relation, such as P3 and P4.Quadrant III factors, known as independent factors or autonomous receivers, have low prominence and relation, like T4, and are relatively disconnected from the system.Quadrant IV factors, termed impact factors or intertwined receivers, possess high prominence but low relation, such as policy nodes. Factors influencing government policies may extend beyond the technology roadmap’s scope, requiring assistance from other analytical models. This observation aligns with the theoretical analysis of the DEMATEL method.

It is worth noting that market nodes often reside in the lower half of the graph, with low relation (R-C). This is because, during the process of constructing system relationships (i.e., when building the technology roadmap), market category nodes are more widely dispersed. Additionally, market nodes often appear at the end of a stage’s sub-graph, indicating the culmination of commercialization in that stage, although some market nodes are indirectly linked to certain product nodes through feedback.

Combining the above analysis, we can easily identify several prominent nodes in the technology roadmap using the DEMATEL method. These nodes have high weights in Figure 7 and are located in or near the quadrant I in Figure 8, such as P2, T2, P3, and T3.

Notably, both the weight map and influential relation map highlight prominent nodes in the early and rapid commercialization stages of the technology roadmap. These nodes align with the Early Adopters and Early Majority stages in the market layer, with connections spanning across these stages. This observation resonates with the chasm concept in the Technology Adoption Life Cycle theory, situated between early adopters and the mainstream market.

Is this just a coincidence?

6.2. Crossing the Chasm

In Section 4.3.1, we briefly discussed the Technology Adoption Life Cycle (TALC) theory and utilized it to analyze the classification of adoption groups, providing insights into the potential new target users for eVTOL at different stages. We also mentioned the gap or chasm between the early adopters of the product (the technology enthusiasts and visionaries) and the early majority (the pragmatists). Furthermore, in Section 6.1, we used DEMATEL to discover that nodes within the eVTOL technology roadmap, which logically need to cross the chasm, hold greater prominence and relation within the system, thus warranting special attention.

Crossing the chasm is vital for high-tech companies as it marks the transition from selling to early adopters to selling to mainstream customers. Early adopters are usually tech enthusiasts, while mainstream customers are more conservative and require more proof of a product’s value. Successfully crossing the chasm can unlock a broader market and sustained growth, while failure to do so can lead to stagnation, loss of market share, or even failure[17].

For specific products like eVTOL, initial interest may come from tech and aviation enthusiasts. However, broad market acceptance and adoption are necessary for eVTOL to become a mainstream mode of transportation. This requires demonstrating technical feasibility, safety, and value proposition, including comfort, convenience, reliability, and affordability. Addressing concerns like safety, regulations, and operating costs is crucial to win over mainstream customers.

So, why not incorporate the chasm into the technology roadmap? This way, the final eVTOL technology roadmap would be complete:

Figure 9. The final P-TRM for eVTOL, with chasm.

Figure 9. The final P-TRM for eVTOL, with chasm.

The key breakthroughs in crossing the chasm successfully should mainly focus on achieving breakthroughs in three areas: the technical feasibility, safety, and affordability.

In terms of technical feasibility, eVTOL needs to develop advanced electric flight technology, including high-energy-density batteries, efficient electric motors, and intelligent power management systems, to meet the requirements for sufficient flight range and passenger capacity. Additionally, infrastructure construction and management need further research and deployment to ensure eVTOL can flexibly take off and land in urban environments, with flexible scheduling.This part has been extensively discussed in Section 4.1.

Safety is one of the key barriers for eVTOL to enter the mainstream market. It requires advanced automatic flight systems, including functions such as automatic takeoff and landing, obstacle detection and avoidance, and flight path planning, to ensure flight safety and stability. Moreover, emergency handling capabilities are also crucial, such as automatic switching to backup power, automatic return systems, and emergency landing procedures, to cope with possible failures or accidents.

Regarding affordability, eVTOL needs to reduce manufacturing and operating costs to enhance product competitiveness and market attractiveness. This involves improvements in materials and production processes, as well as the optimization of scale production and supply chain management. The realization and application of fully automatic flight are imperative; otherwise, it would be challenging for companies and individuals to afford the high costs of training and employing professional pilots. Furthermore, price competitiveness is also critical, and eVTOL needs to ensure that product prices are competitive to attract mainstream customers’ purchases.

In the future, as eVTOL enters the mainstream market, the above three aspects based on technology and product must be realized, and they need to meet market expectations. The achievement of these goals must start from the early commercialization stage, or even from the present.

Government policies play a crucial role in shaping the commercialization path of eVTOL. As shown in Figure 4, “Representative Policies for China’s NEV Industry,” substantial policy investment often aligns with the transition from early to rapid commercialization, as identified by the TALC theory. Therefore, strategic policy support is essential for facilitating this transition. In China, while numerous policies aimed at fostering the low-altitude economy have been introduced, most policy issuers are local governments, and progress remains largely at the conceptual and planning stages. Overcoming significant obstacles and streamlining policy guidance and support for eVTOL remain pressing challenges.

In conclusion, the successful commercialization of eVTOL hinges not only on technological breakthroughs and product innovations but also on the effective implementation of marketing strategies and supportive governmental policies. By addressing these multifaceted aspects in a holistic manner, eVTOL companies can navigate the challenges of crossing the chasm and unlock the full potential of this transformative technology in reshaping the future of urban transportation.

7. Conclusions

Table 6. Measures for crossing the chasm.

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