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For those early career high-altitude survey contracts, I, like many of you, have traditionally opted for a combination jet engine/rocket engine plane, where the jet engine gets me to the contract location and I then jump to the necessary high altitude using the rocket. It gets the job done, but it's tough to meet early game weight and part count limits, the craft is often limited in range, cruising speed, and number of high-altitude jumps, and I'm eager to ditch the whole design as soon as I unlock new tech nodes (especially the Panther). What if I told you there was a different way to fulfill those contracts, where all you need is...drumroll...curtains parting...the Juno? Though Junos are generally low thrust, low altitude engines, they're actually pretty capable when you use a bunch of them on a lightweight aircraft to get a high TWR. Using only four, I managed to get a craft to 1.5-2 TWR depending on fuel level, which was enough to reach a 600+m/s cruising speed, 630+m/s max speed (see second image below of the plane descending from cruise in preparation for a jump), and a max altitude of over 20km per jump (see third image below). Because it can cruise at over 10km and 600m/s, it's actually got a pretty big range as well, and if I need to reach a faraway target I can load up the Mk1 fuel tank (see image below), and by the time it arrives at the jump point it will have used enough fuel to get the TWR back up to the level where it can support a high-altitude jump. Some notes on the design (see first image below): This design uses well under 30 parts (so you can customize with the science parts of your choice), meets all early game runway/hangar limits, and doesn't use anything beyond tech level four. I experimented with using a longer tail/traditional front wing/rear tail body design to minimize the risk of flipping, but any gains in stability were offset by a lower max speed and more limited turning ability that prevented me from going fully vertical in the jump, and ultimately limited the plane's max altitude too much. The engines are placed as far forward as I can without limiting a pilot's ability to exit the craft, and the rear wings are as far back as I felt comfortable with, which enabled me to nudge the COL behind the COM. The COM is even more forward when the Mk1 tank is completely full, but I rarely keep it full so I can maintain a high TWR. In general, having the COL really close to the COM provides maneuverability that helps in transitioning from supersonic horizontal flight to a vertical high-altitude climb, and in any event the plane doesn't really have a flipping problem. Control Surfaces - I limited all of the control surfaces (especially roll) below their defaults, because otherwise the plane can be a bit twitchy at high speeds. I also recommend using fine controls for most if not all of the flight. I experimented with increasing the AOA of the rear wings to squeeze out a little more efficiency while cruising, but the plane kept flipping on takeoff. Leaving the wings horizontal eliminated the issue, and the plane is surprisingly efficient as is. Flight Tips: Be gentle when pulling up to take-off! The plane isn't particularly flip-happy, but the only time it would happen is when I pulled back too hard during takeoff. This thing builds up speed really quickly, so you should be able to nudge it into the air with relative ease. To repeat what was stated in the design tips: consider using fine controls for most/all of the flight. Use the lower atmosphere to build up speed. I shoot for an AOA of no more than 10 degrees until I reach 5-6km in altitude, and then 5 degrees or lower until I've reached around 600m/s and between 8.5-10.5km cruising altitude. I can usually get a fuel usage rate of .08 units per second or lower (visible in the resource app) under those cruising conditions. Once you approach the target location, descend slightly to max out your speed (I usually get around 630m/s), and then gradually (I can't emphasize enough that it has to be gradual) raise the nose of your craft until you're fully vertical at around 18km- you should be able to hit 20km in altitude like this, which should be sufficient for most high-altitude Kerbin survey contracts. The turn needs to be gradual; you're looking to convert horizontal speed to vertical speed, not rapidly dump speed/raise drag with a sudden attitude change. Keep an eye on your speed and g force meters. If your speed is jumping down rather than slowly descending, or if you encounter any high g forces, you're probably wasting energy, and your max altitude will be lower. Unlike rocket plane jumpers, where you try to go vertical as quickly as possible to make the most efficient use of your limited oxidizer, don't go fully vertical too quickly. You can only raise your apoapsis if the Juno is thrusting, so until you reach 18km keep shy of full vertical so you can squeeze out a few more seconds of thrust while climbing, or at least until your apoapsis display shows that you've exceeded your target height for the jump. Once your engines flame out, go full vertical to maximize the use your remaining airspeed which should nudge that apoapsis a teeny bit higher before it starts coming down due to drag. Landing: This plane handles just fine at 50m/s or below. When coming in for a landing I often have the throttle at about the 1/6 mark, which gives me just enough speed to get into position without needing to land at high speed. As an early-game craft, there are no airbrakes/reverse thrust capabilities, so you'll have to bleed off speed by maneuvering alone (from 600m/s to just over 100m/s) when approaching the KSC and then using the rear landing gear brakes only (there's no brakes for the front wheel). I haven't needed to deploy ailerons to improve low-speed handling but that's always an option. As you unlock more tech nodes/higher KSC levels, you can add more Junos, streamline the landing gear/wings, or make other improvements, but even without those this is a really capable plane that you can continue to use into the mid-game for as long as you continue to get Kerbin altitude survey contracts. Not only does it save you the need for a full redesign as the game progresses, but since it travels at 600m/s, these survey missions go by faster and feel a lot less tedious. There's still a place for combo jet engine/rocket planes, especially for part testing contracts where you're looking to reach far beyond 20km, as well as eventual SSTOS, but sometimes MOAR JETS on a lightweight body is all you need. I've written a bunch in this post, but the main takeaway is managing your TWR can squeeze a lot of performance out of seemingly unimpressive plane engines and parts. Link to full Imgur page with picture annotations

I saw this video by Scott Manley where he went over an ion engine that collects air from the upper atmosphere and uses it as fuel to stay in orbit. I think this could have some rather... interesting uses in KSP. Things such as ICBMs and crafts for traveling to and from a planet's moons. It would also be cool if we could store some of the gas in tanks for use in orbit. Here's the video -

I need an intake that works well at roughly 55,000m and up. Is that even a thing that can happen? How do I make it happen?

Can we build something similar to the stratolauncher that jettisons it's landing pylons (which has fuel that is burned off initially to carry a spaceplane to high altitude that then heads to another planet's orbit. Easy: Get the spaceplane to CisMunar orbit and return after landing and then dropping something (10 tons) there. Harder version of easy is to also carry 60 Kerbals. Medium: Same as Easy but on Dun. Harder version is dropping 50 tons. Hard: Launch to Duna, land, drop 25 kerbals, land on Ike, drop 10-40 tons as well as 30 kerbals. Make a refueling stop at Ike, burn towards Mun, land, jettison 15 tons and then reenter kerbin orbit without assistance.