Another update from David.
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Okay, I'm going to try this one more time.
The argument was that frigates make more sense than destroyers. Frigates do not make more sense than destroyers for any possible mission. Now, if the object is to discuss building some vessel other than a frigate for a specific mission, that's an entirely different proposition. It was not the question as originally posed, although, if you will notice, I suggested in my long post on this topic that building something on the order of an Orion — that is, a completely unarmed, small-manpower, hyper-capable vessel solely for reconnaissance purposes — might (and I emphasize might) be a reasonable proposition. If, however, that's what you're proposing, then it isn't a "frigate" at all. It's something else entirely, that would be a new departure, and saying that I don't understand the logic that makes a frigate desirable or even necessary is inaccurate, because you're talking about something else entirely.
A frigate is a light warship capable of independent interstellar deployment; a pure recon platform would be, at best, a drone tender. It certainly would not be a warship.
Having said that, I still don't see Manticore needing or building the type you're discussing. And the reason I don't see Manticore needing or building the type is that their vulnerabilities are clearly not what you seem to be thinking they are. Or, rather, the solution to the problem which you envision (note that I did not say "which you invented," although the temptation was there) is far in excess to the need and would require the diversion of lots and lots of badly needed resources from platforms which would be combat capable at need to platforms which would be completely non-combat capable. Before you point out (again) that I'm clearly missing the point because the type we're talking about (now) doesn't have to be armed at all to accomplish its mission, note that I said platforms which would be combat capable at need. In other words, platforms which would be capable of a somewhat more demanding mission than the one you've sketched out and (would therefore actually constitute a useful addition to the RMN's war-fighting ability, as well) in addition to running around like chickens with their heads cut off on recon missions.
All right, first what exactly constitutes Manticore's recon requirements where spider-drive ships are concerned? The problem from Manticore's perspective with the original Oyster Bay attack wasn't that they failed to detect the Sharks arrival but that they failed to recognize what it was. They picked up the attack force's hyper footprint, but the fashion in which the attack force made its alpha translation was very carefully designed to disguise the footprint and make it look like a sensor ghost. The defenders had no reason to believe that it truly was an alpha translation, yet they treated it seriously and dispatched a response force to the location of what they believed was a false datum, where the response force proceeded — very diligently; they took their responsibility seriously even if the odds were overwhelmingly that it was a wild goose chase — to search anyway. Unfortunately, they didn't know (then) that anyone had a reactionless drive that didn't rely on an impeller wedge. It wasn't that they weren't looking; it wasn't that they didn't get there in time; it was that they were looking for the wrong thing because they didn't know the right thing existed. That's not a hardware failure, it's not a ship availability failure; it's arguably an intelligence failure, but I personally would disagree even with that. They did everything right; they simply didn't know about an entirely new threat no one else in the entire galaxy had ever seen.
The significant delay element in getting the destroyers to the locus of the footprint was the time necessary for that footprint to reach the enormous passive sensors necessary to pick something like that up at extreme distances. It wouldn't have mattered whether they'd had frigates deployed instead of destroyers, the transit time would have been effectively identical. Nor, for that matter, would speed in getting there have been the critical factor if they'd known what they were looking for in the first place. Had they realized that someone could accelerate ships without using a reaction/fusion drive or an impeller wedge, the logical thing for them to do would have been to send a larger force (which would have been readily available out of on-call destroyers) to englobe the locus and then deploy remote platforms for all they were worth. The acceleration rates of the individual units are really pretty much immaterial, as is the number of individual hulls, as long as they can carry a large enough combined number of remote platforms. Initial detection depends upon the huge, passive arrays; once that detection has taken place — and been recognized — the Royal Manticoran Navy has all of the "rapid response" vessels that it needs in the form of destroyers. And the sensor suites available to your non-frigates are going to be sufficiently inferior to the passive arrays as to constitute no net increase in detection reach. Again, it's not a matter of numbers of platforms, but rather of their sensitivity, and the existing passive arrays are fully sensitive enough . . . if they know what to look for in the first place. And please note that I'm not talking about picking up the spider drive; I'm talking about picking up the hyper footprint. On the other hand, anyone arriving from an interstellar distance is still going to radiate a hyper footprint, the detection of which has to be any star system's first line of defense against spider drive-ships.
If your thought is that they're going to smother the area outside the hyper limit with frigates — I'm sorry, with non-frigates — in order to significantly reduce response times and possibly even pick up spider drives coming in (somehow) without hyper footprints, then how many of them do you intend to build? How heavily do you intend to saturate the area outside the hyper limit, and how big a zone do you intend to saturate? Detection range against the spider drive is going to be very, very short. (I'm not going to tell you how short just yet, but it's safe to say that it will be substantially less than five light-minutes unless you already know essentially where the target is.) If you assume a hyper limit of 20 light-minutes and you further assume that you're going to cover a zone that extends merely another 20 light-minutes beyond the limit, you're looking at an area of 234,572 cubic light-minutes. Are you going to distribute one non-frigate for every ten cubic light-minutes? Fifteen? Twenty? If you call it 15 cubic light-minutes, you're going to need 15,638. So let's call it 30, which will reduce your numbers requirement to a "mere" 7,819. Assume you can get the crew all the way down to only ten trained personnel (trust me, you'd be looking at more than that if they were going to remain instantly deployable over any extended period), and you get damned near 80,000 personnel who will be sitting around in completely unarmed vessels serving no other useful function at all. Somehow I don't see the Admiralty viewing that as an efficient usage of manpower, building materials, or logistics, especially when the Admiralty already has a perfectly adequate quick response force now that it knows what to look for in the first place.
The other side of that equation is that if they invest the money in something like a Roland, it will be able to carry out the quick response recon function you're talking about and, even if the non-frigate you're now talking about cost only 10% as much as a Roland, they'd have an additional 781.9 Mark 16-capable destroyers which could also be used for other duties at need.
Building thousands of ships for "quick response" recon is one of the best examples of a solution in search of a problem I've seen in quite some time. It would constitute a panic reaction on the part of the RMN which would have a significant impact on the ability of the RMN to maintain a useful combat capability.
If I were designing the RMN's "quick response" recon forces (which, by an odd coincidence, I am responsible for doing) they would be built around a small number of specifically tasked groups of destroyers and a single CLAC. They would be dispatched to the coordinates of any suspect datum, and once they reached those coordinates, they would be tasked to search a volume around them which would allow for a rate of advance by any incoming force which would be at least twice that of which I believe the attackers to actually be capable. They would deploy recon platforms in profusion and they would operate two shells of RDs: one working its way in from the outer perimeter of the sphere to be searched, and another working its way out from the center. The CLAC would remain a light-minute or so away from any anticipated danger, staying in contact via FTL com, and would be available to provide a massive launch of LACs if an opponent suitable for its engagement turned up. If, instead, an entire enemy Battle Fleet turned up, then Home Fleet would be on call to deal with it. And, in the meantime, I would not have invested billions of dollars, hundreds of thousands of tons of shipping, and tens of thousands of personnel in a fleet of ships which had no other function but to run around, look for the enemy, and either run away very fast — or die — if they detect the enemy.
Wasting resources on that mission when that mission can already be accomplished by existing combat types which can also serve other useful functions is logistically and economically insane.
