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I was making some cool fictional airplane designs and realized that most of my larger airplanes have a bay inside that stores a plane or two. But then I thought, is it even possible to make a plane exit and enter a plane mid-flight? Such a plane to enter another plane would need to have folding wings to take up the least space when stored, and also because the plane it is entering would have to be significantly larger to have a fuselage wide enough to fit a smaller plane's entire wingspan. Note that I am questioning if it is possible to do something NOT in an emergency, but as a tactic or for other reasons. That being said, the question differs from an emergency situation due to the fact that the question is implying that the operation be done over and over, and not in a risky, dangerous, last-resort fashion.

This mainly branches two questions: Is it possible for a plane to exit a plane mid-flight, and if it is possible for a plane to enter a plane mid-flight. Clearly the plane must enter and exit through the belly of the larger plane, because something like a large hydraulic arm would be necessary to "grab" the small airplane and allow it to fold its wings up before hoisting it into the plane. This came to mind after considering that the plane must folds its wings up before entering the plane, and it also must take at least 5 seconds to fully fold the wings. So, folding the wings mid-flight independently isn't a good idea: The plane will plummet without wings to lift it. And to exit a plane, I'm assuming the arm will have to hold the plane out of the bottom and allow it to fold the wings out before dropping it. But here's what challenges that idea: When the arm is holding the plane and plane's wings are extended, will the little plane's wings effect the flight of the Larger plane? (Since the arm is grabbing it, it is the equivalent of the large plane having two tiny wings below it) and also, what are the effects of dropping a plane mid-flight? Any help on this would be very, very appreciated.

Oh, and a side-question from the above: Would a plane large enough to fit another plane be large enough to reasonably carry the weight of that smaller plane? And if so, how will the larger plane fair considering the fact that such a hydraulic arm necessary for mid-flight entry and exit of the large plane must be considerably heavy?

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    $\begingroup$ Not quite. That question has answers that would differ significantly from this question. See, that question literally specifies it as a last-resort, an emergency. Another critical difference is that I am also asking if it would be possible to exit the plane as well. It might also be helpful to consider that both these aircraft would likely be designed to do this maneuver repeatedly. $\endgroup$ – Ginger May 26 at 0:42
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    $\begingroup$ Some post WW2 bomber designs had parasite fighters; the fighters would be deployed by a trapeze, do their thing, and come back to hook on. It didn't really work. en.wikipedia.org/wiki/Parasite_aircraft (I just looked at the wiki and the concept pre-dates WW2!) Looks like the first picture in the wiki article has your "hydraulic arm". It kinda sounds to me like you've reinvented the parasite fighter. $\endgroup$ – Organic Marble May 26 at 0:55
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    $\begingroup$ @OrganicMarble yeah, the Soviets and Americans both experimented with the concept prior to WW2, ultimately unsuccessfully. $\endgroup$ – jwenting May 26 at 9:28
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    $\begingroup$ Ginger,look at sacmuseum.org/project-ficon-and-the-b-36 for a real world example that kinda worked but never entered production $\endgroup$ – jwenting May 26 at 9:39
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    $\begingroup$ @user_1818839 - as distinct from the garbage remake someone made a few years ago ! $\endgroup$ – Fattie May 26 at 18:19
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Clearly the plane must enter and exit through the belly of the larger plane

Why so? If you drop this condition, things become much easier, because you could attach the smaller planes externally and avoid folding the wings. And this was indeed tried and even used operationally.

The concept is generally termed as Airborne aircraft carrier. The first (?) and most obvious application of the idea was with airships, where the airplanes could indeed be stored internally.

USS Akron/N2Y Wiki

Russians extensively tried the idea in the 1930s with up to 5 fighters attached on or under the wing of a large bomber.

ТБ-3-4AM-34FRN Wiki

Admittedly, this configuration was mostly indended for deployment of the fighters, which would then land normally. This way it was used several times successfully for bombing raids early in the WW2. Recovery of fighters was tried, and some configurations even assembled in the air rather than on the ground. But it was quite difficult and required considerable skills even without any folding wings.

During the tests, on some occasions, there were problems (including at least one fatal incident) you are worried about, namely negative influence of the fighters on the carrier. Mostly they were related to failures, when the attachment broke down or didn't work as expected (sometimes due to incorrect control of the fighter during the process).

However, even pretty much the same idea as yours was explored in the 1970s, with the B747 or C-5 as the carrier and some "microfighters" as the payload. Apparently, the concept was deemed "feasible" but never went to an advanced stage of development. Yet today, the idea may be of some interest again with UAV aircraft.

747 AAC Wiki

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    $\begingroup$ The 747 AAC has a touch of the Marvel Cinematic Universe to it! $\endgroup$ – GdD May 26 at 8:13
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    $\begingroup$ The concept has been used with UAVs mounted under the wings of C-130s during the Vietnam war. These were however not recovered in the air but flown to friendly occupied territory and landed (usually crash landed, as they had no landing gear). $\endgroup$ – jwenting May 26 at 9:30
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    $\begingroup$ The aviation channels Mustard and Dark Skies have numerous micro documentaries about experimental parasite aircraft e.g. youtube.com/watch?v=WE4Uxo6WLio en.wikipedia.org/wiki/Parasite_aircraft Also, if you like the 747 AAC you should look up Japan's WWII underwater aircraft carrier! $\endgroup$ – Roger Heathcote May 26 at 10:47
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    $\begingroup$ the people designing the 747 AAC must have watched too much Battle Star Galactica! $\endgroup$ – keuleJ May 26 at 11:08
  • $\begingroup$ For another nice example see Mercury and Maia, the Short-Mayo Composite. Use case was a range extender to allow a mail plane to cross the Atlantic. (Carrier launches mail plane inflight and returns to base, presumably around 1/3 of the way across. No inflight landing possible. en.wikipedia.org/wiki/Short_Mayo_Composite $\endgroup$ – user_1818839 May 26 at 14:24
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It was actually done post-WW2 as part of the USAF FICON and Tip Tow projects which thought to extend the service life of the B-36 by giving it some escort fighters and photo reconnaiscance aircraft for damage assessment.

It ultimately wasn't put into production as it was rather dangerous and seriously degraded the performance of the carrier aircraft, meaning they'd be incapable of keeping up with the already slow bomber formations.

http://www.air-and-space.com/ficon.htm shows a lot of details of the actual system as built into the B-36 carrier aircraft, and photos of the parasite fighters involved.

"In parallel to both FICON and TIP TOW, project TOM TOM was being developed using a JRB-36F and two RF-84F. Using a newly designed articulated arm and clamp system, the RF-84F was intended to attach to the JRB-36F and be towed to the target site. The JRB-36F retained most of its cameras to record flights and the RF-84F would retain four of its .50 guns for defensive action for itself and the “Mothership.” Turbulence and vortices continued to be a problem for the RF-84F pilots, with one aircraft actually being torn from the JRB-36F in-flight. The program, much like TIP TOW was cancelled." from https://sacmuseum.org/project-ficon-and-the-b-36/ gives some details of the problems encountered.

In the end it was decided to retire the B-36 and build more B-52s instead.

For non-military missions, there were also the X-1 experimental rocket planes carried aloft by B-29 motherships and X-15s by B-52s, but those were incapable of being retrieved in flight.

enter link description here lists some other projects with similar concepts that actually flew.

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Consider a C-5 Galaxy and a T-38. Big and little.

The C-5 cargo compartment is 19 feet (5.76m), The T-38 wingspan is 25 feet (7.7m). So not going to fit. Weight capacity of the C-5 is 291,000 lbs, and the little T-38 onl weighs 12,000 lbs or so. So THAT isn't the problem.

Now...if you were to park the little jet on a platform extended from the back, and then fold the wings before pulling it inside, sure.

The question is, outside of fiction...WHY would you do this?

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  • $\begingroup$ there are multiple benefits that it has. If you're flying a large plane and you're fighting enemies, and the enemies are tiny, zipping around all over the place, not an ideal match for a large plane. Sure, the large plane is stronger, but it just sits there, being an enormous target. Then you could switch planes to a smaller plane suited for dogfighting. $\endgroup$ – Ginger May 26 at 0:33
  • $\begingroup$ How would you switch planes? It'd have to be inside of your plane. Because you can't just swap with an airplane flying right next to you. That's risk and dangerous. And if this is a long-distance mission, the little planes couldn't come as escorts because they wouldn't be able to travel such a distance on their own. It can also serve to surprise the enemy. If the enemy doesn't know you have an escort because it is IN you, then they couldn't possibly plan ahead and attack you with the planes suited for fighting escorts, now could they? $\endgroup$ – Ginger May 26 at 0:35
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    $\begingroup$ Outside of fiction (that would not be believed), air combat does not work like that. $\endgroup$ – WPNSGuy May 26 at 0:54
  • $\begingroup$ @Ginger how would you get into the parasite if it's (partially) external? With some difficulty and acrobatics. As was shown by the test pilots of the USAF FICON project, and the pilots of some of the later X-1 derivatives who'd climb through the bomb bay of the carrier aicraft, lower themselves into the parasite aircraft's cockpit, and in reverse during longer flights. And no safety harness, if they slipped it was a long way to the ground below with no parachute. $\endgroup$ – jwenting May 26 at 9:33
  • $\begingroup$ @WPNSGuy yet the USAF seriously investigated it for their B-36 fleet to keep them relevant in the face of Soviet jet fighters capable of intercepting them. It was deemed too dangerous and never put into production, but several (I know of at least 3 just for the B-36) attempts were made. $\endgroup$ – jwenting May 26 at 9:37
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Sure, it's possible. There have been several experiments with so-called "parasite aircraft" over the years, some of which even managed some success before inevitably being canned for reasons of practicality and cost.

Docking them together is going to be the hard part. A hydraulic claw won't work; aside from the sheer weight of such a device, planes bounce around way too much to have a realistic chance of grabbing one mid-flight.

I'm picturing something similar to current midair refueling equipment. The big plane would trail a cable that engaged with a (deployable?) hook on top of the small plane. As the little one shut down its engines and folded its wings, it would naturally fall beneath the big one, and could then be winched in. Still not remotely practical, but believable enough for a fictional world.

Will the little plane's wings effect the flight of the Larger plane?

Yes, but only slightly. Any reasonably competent pilot could compensate easily.

What are the effects of dropping a plane mid-flight?

The big plane will suddenly be a lot lighter. The pilot would need to push forward to avoid climbing (although, come to think of it, they probably want to let it climb, at least a little, to reduce the chance of a midair collision). It would, in fact, be very similar to dropping a bomb, so you could look up info on big bombers for inspiration.

Would a plane large enough to fit another plane be large enough to reasonably carry the weight of that smaller plane?

Shouldn't be a problem. After all, big cargo planes carry multiple fighters to deployments all the time.

How will the larger plane fair considering the fact that such a hydraulic arm necessary for mid-flight entry and exit of the large plane must be considerably heavy?

As mentioned above, a hydraulic arm would be the least likely part of the little scheme, which is why I recommend cables and winches instead.

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Landing a plane inside another plane would entail the airspeed falling to zero, which would be possible during parabolic (zero-g) flight, although the control surfaces would become inoperative, so some kind of thrusters might be required. Failing that, if the larger aircraft were open at both ends it would be rather easier. I’ve seen paragliders deploy from helicopters and microlights; in principle many types of aircraft could be deployed in flight provided that they can stay within their safe envelope while adjusting to the airflow.

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    $\begingroup$ no parabolic path needed, you "just" need to perfectly match your airspeed with that of the carrier. Some sort of trapping mechanism would almost certainly be deployed to kill the last bit of relative airspeed. $\endgroup$ – jwenting May 26 at 9:35
  • $\begingroup$ Putting the carrier aircraft into freefall really doesn't make anything less complicated. It not only makes it difficult for the landing aircraft to land, it imposes hard time constraints on the approach. $\endgroup$ – Erin Anne May 26 at 21:48
  • $\begingroup$ Having no relative airspeed is ok until you suddenly have no drag and must therefore reduce thrust to zero, and have no lift. That’s not ‘just’ anything. While the mathematics may be no more complicated, the reality is that a straight and level approach has far less margin for error than a parabolic path. $\endgroup$ – Frog May 27 at 10:57

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