July 23, 2021, ©. Leeham News: Last week, we went through the initial tasks in the Prelaunch Phase. We talked about Sales and Marketing activities, initial Concept development, and first Supplier contacts.
Now that time has passed, we are three quarters into our Program Plan (Figure 2), and we have to refine our Concept, select Suppliers, and dig deep into how to get Certification.
We are now three quarters into our two-year Pre-Launch Phase, Figure 2.
It’s time for us to get going on the following fronts:
By now we shall have picked a final CAD/CAM package where we can create and store the final external shapes after the analysis in our CFD tools. As we see the form of the aircraft and its movable surfaces mature, it’s time to do a detailed windtunnel model. Once again this is focused on the low-speed regime, takeoff and landing.
Now we must have the final wing shape and high lift configuration so we can predict the maximum lift in takeoff and landing configurations, and also measure the moments these configurations generate on the aircraft.
The moments give us input, together with the engine thrust for single-engine takeoffs, for the final sizing of our empennage surfaces (vertical and horizontal tails). The windtunnel model we either make or let make is larger and more detailed than the first one. Size is important to get good data so we might go for a half model at a scale of 20% of the real size, Figure 1.
The data shall be part of our design database, giving the stress loads on all parts of the aircraft from normal aero loads but also extreme cases like gusts. We also need other loads like hard landings and engine-out flight cases. Once we have this dataset we can test different structural concepts for weight, flutter and fatigue resistance, and production cost. Our aero and stress engineers are maxed out during this period.
With the data from CFD and the windtunnel and initial system configurations, we can make the first Functional Hazard Analysis (FHA). Now we test what the hazards to aircraft are if systems fail, such as the flap system deploying asymmetrically caused by e.g. a sensor failure, or not at all due to hydraulic failure. We need these first FHAs for internal work but also for discussions with the Certification Authorities, see below.
Our engineering and purchase teams are now hard at work to select suppliers for Structures, Engines, Landing Gear, Avionics, Flight Control Systems, Fuel System, Environmental Control Systems (ECS), Hydraulic and Electrical Systems, Bleed-Air system, De-Ice System, Cabin and Cargo equipment etc. We also need a supplier for our Electrical Wiring Interconnect Systems, EWIS.
We need to establish the type of contracts we shall have with the suppliers such as time schedule and price for initial deliveries based on our present versions of specifications for all the parts.
Any milestone payments for shipments must be agreed upon, and how is the inevitable learning curve handled. Does the supplier absorb the extra cost for initial shipments or do we? And how do we get the benefits of the cost down as deliveries reach higher shipset numbers (the extra cost of initial shipsets can last until past 200 units, dependent on if we have a new design or use one already in production at the supplier)?
Our contract shall regulate how we handle specification changes. These are inevitable as the aircraft and our project mature. It’s better to agree on how such changes affect delivery and costs upfront.
We discussed how certification standards shape our aircraft in previous articles. As we advance through the Pre-Launch Phase we need to understand how we can get certification compliance in several target markets:
The choice of State of Design that will grant the type certification is important. It determines the certifying authority (e.g., FAA, EASA, etc.) for the project. All other certification decisions are influenced by this decision. Examples of what we need to think about:
In addition to the question of where we get the initial type certificate, we need to understand where we will need to validate that certificate in order to sell aircraft. This is based on our sales forecast: Asia, Africa, and South America and potentially Europe/Canada for the passenger variant, and the US for the cargo variant.
Certification and Sales departments need to work together to establish the timelines in each region, so we can deliver when we need to.
For example, it would be very difficult to deliver in the first quarter of our delivery program to China (under the CAAC), Brazil (under the ANAC), and the USA (under the FAA), as each of these agencies require substantial certification/validation efforts.
We could try to engage them simultaneously, but this risks instability around the initial design as these agencies give us their requirements and it would be difficult for us to fulfill these requirements in one go. It could delay our program if we try to shoot for too many validations simultaneously.
On the other hand, waiting too late to make an engagement could result in a surprise design requirement that delays validation and delivery to that specific country.
All this work with the certifications is underestimated by all upstart projects. We have yet to hear of any upstart aircraft program that says “by the way, the certification efforts were as planned, and we got the certification when we planned it“.
We go back to this critical and chronically underestimated part of aircraft projects as we dig deeper into our program.