TBH a lot about the Tempest is just as unclear, although its PR has been different from FCAS. If you look at corporate PR from Airbus and Dassault, there's a lot of confidence in FCAS. There has been more public political discussion about FCAS but I suspect that this is partially because the main Tempest partner has been busy with other stuff for the past year or two. Italy's role in Tempest is far from clear and Leonardo is an aircraft manufacturer on the same level as Saab. How can all three major partners get a large enough slice of cake? (ofc FCAS has the same issue)
You have confused some aspects of Tempest above. For starters, Leonardo UK is and has been involved with the Tempest program since the start. With Italy joining they will bring additional expertise and assistance and it could very well come via Leonardo Italy but that, I believe, is yet to be determined.
Tempest is supposed to be a platform "open for other partners" but once the key airframe parameters (payload, range, speed) are defined, the only variable component is the electronics. Not too different from, say, the current Eurofighter arrangement. In fact, Tempest and FCAS will share many systems with the Eurofighter and thus each other. One could argue that new program partners can provide external systems like loyal wingman drones but the same applies to FCAS, which is designed to be a "system of systems".
For sure the interfaces and protocols will be written to allow a reasonably smooth interface between the primary air system and associated components, wingmen etc.
The article posted in the FACS thread by myself and then reposted by Keesje also points to the difficulties that will be faced by the Eurofighter consortium on trying to testbed systems on the Eurofighter. The advantage the UK has though is they have the most capable Eurofighter variants and have a history of continuing to upgrade their aircraft. That is different to both France, where a number of Rafale will stay in earlier configurations such as no AESA radar for the whole fleet, and especially Germany who have not upgraded or even acquired some of the systems used by other Eurofighter operators.
Finally, two of the three Tempest partners have an easy way out by dropping the program and ordering more F-35. If you count Japan as a potential partner, that's three out of four. FCAS on the other hand has two of three partners with no other option, France (who will never buy a US fighter jet) and Germany (who is loyal to France).
I really don’t think this is an issue. Yes the F-35 is very likely to continue to evolve and will likely rival Tempest for capability in the early days of Tempest but the intent of Tempest is industrial preservation. If acquiring more aircraft at the lowest cost was the intent then neither this program nor FCAS would go anywhere.
Another example below of how the Tempest program looks, to me, like it is heading in a more concrete direction. Leonardo UK demonstrates Tempest radar tech
https://www.shephardmedia.com/news/digi ... adar-tech/
Leonardo UK has demonstrated new radar receiver/warner technology for the Team Tempest programme.
The new sensor, which is 1/10th the size of a standard system, demonstrated a direction finding performance of four times what is possible with a typical radar warning receiver.
Leonardo UK is one of the four founding members of Team Tempest, which was brought together by the UK Ministry of Defence to develop a next-generation combat air system for the UK and partner nations, Italy and Sweden.
The company is working to develop Tempest’s sensor package and integrate these sensors into the platform’s mission system.
The new radar warning technology is used to sense the radio frequency signals emitted by potentially hostile radars and then use this information for a variety of uses, including warning an operator that an enemy is trying to lock on to their aircraft. The sensors can also support tasks such as intelligence gathering and combat identification.
In future, threat radars are likely to use a range of technologies and software techniques to make it harder to identify their signals, meaning that Tempest’s sensors will need to be sophisticated enough to be able to counter such techniques and flexible enough to be updated in response to new technologies as they emerge on the battlefield.