What is the maximum mass for a reentry capsule that can be recovered in the air?

Question

Landing rockets take away precious mass from the space system mass budget. Recovering capsules in the air from helicopters and planes equipped with hooks and winches has a long tradition since after WWII (Genesis, CORONA, etc.)

• How large can the capsule be (as a proportion of the mass and size of the recovery aircraft, and in absolute numbers for the largest aircraft out there - including helos and tiltrotor craft)?
• What are the mass savings (approximately) compared to the conventional landing mode choices (using retrorockets for soft landing, parachute all the way down without retrorockets, parachute and splash on water, parachute and use inflatable cushions)?
• How does re-entry targeting accuracy depend on the speed and maneuverability of the recovery aircraft?

Answer 1

So a quick bit of research has told me the highest lift chopper is the Mil Mi-26. This chopper has the highest lift of any chopper to go into production so it's probably going to be a likely candidate for capturing your as-heavy-as-possible reentry craft. This chopper can lift 20 metric tons - for comparison you'd need 24 of them to lift the ISS! (Although the chopped holds the record for being able to lift 62 tons to 2000m - that'll mean you only need 8 to lift the ISS).

When talking about mass savings it's very, very dependent on the reentry vehicle in question. If it's a manned mission it would certainly have redundancies which multiply the mass required. A parachute and spashdown would probably be the closest approximation in mass, in that both require a parachute to reduce the speed and the rest is on the recovery side. All other system, retro rockets etc are much more massive, they often require bespoke propulsion systems that aren't used at any other time of the mission.

Reentry accuracy and recovery method both feed into one another. If your reentry footprint size is too large you wont be able to use this sort of method. It may be that the mass savings you get from not requiring retro rockets are spent on hardware to allow a more accurate reentry making this method not worthwhile.