I don’t see why anything that flies can’t skip, just gain altitude for a moment then lose it for a moment. This did take place in the mountains where updrafts make you do exactly that. And since there were several objects in a row bobbing up and down, “skipping” would be a good description.
Just imagine a line of anything flying together and each one momentarily gaining altitude then settling back down. Or watch a war movie featuring flights of helicopters. They often skip. It seems to me that any flight of birds, planes, aliens or supermen flying together in the mountains would have a hard time not skipping.
If you expect, after 60 years, to get something like this:
“I was the pilot of the super-secret aircraft, the FU-69, built at the Skunkworks, and it flew exactly like that, and I have pictures!”
…then dream on. It’s highly unlikely that “what Arnold saw” was an actual, solid, built-and-flown, object remotely resembling what he reported.
It’s highly likely that other more mundane explanations fit the situation better. You are asking for speculation about a speculation about a nebulous, badly-reported event and you still want concrete evidence that it was something real when none has come forward yet? Get real.
After reviewing Arnold’s account, I think the vertical oscillation that a ‘skipping saucer’ evokes might be a misinterpretation of what he meant.
According to Wiki, though he described their flight behavior as erratic, he also described it as horzontal:
"Though moving on a more or less level horizontal plane, Arnold said the objects weaved from side to side (“like the tail of a Chinese kite” as he later stated), darting through the valleys and around the smaller mountain peaks. "
It is interesting to note that there were two other reports of what would be the same objects also mentioning bright flashing, high speed and erratic flight but not vertical oscillation. Arnold counted nine objects in rough and extended formation, perhaps the skipping saucers bit was meant to evoke the appearance of the formation flight rather than individual objects.
Other than skipping stones and hypothetical craft like Saenger’s that are interacting with a transition between mediums there really aren’t any skipping artificial flying objects. Some song birds do indeed fly with a pronounced vertical oscillation that can be quite visually intriguing when in a group.
I don’t think the descriptions from the time present a good picture of what he saw (presuming he saw anything at all). Finding an aircraft that someone else describes as ‘like a saucer skipping over water’ won’t tell us very much as it’s likely to be about some other motion altogether.
Ok, it’s possible for many aircraft to fly in a manner that could be described that way. They would accelerate and climb on a shallow incline, then reduce power and retard lift to drop briefly. Some planes actually do something like that when landing.
Is this a special maneuver that is some kind of stunt flying? It doesn’t sound that you would spend a whole flight doing that. Is this related to the phugoig oscillation that AndrewL mentioned?
What size or kind of aircraft would be flown this way? Is it something that only a small, light plane would do? Would any military aircraft be put through this, as a test sequence e.g.?
What about altitude? Would you be limited at the heights you would do this because of the risk? Are their other limitations, like speed of the craft?
Can a formation of planes all do this at once, even assuming a trained stunt team, or would it be difficult even for them?
If there are other issues that I’m missing, assume that I’m asking them as well.
Not phugoid oscillation which I believe is due to inherent instabilities, it’s deliberate. I think theirs a term for it when used in landing, but I’m rusty on that stuff. What I recall is that in landing the idea is to control descent rate with more thrust from the prop rather than changing your control positions. I’ve never heard of this done through a whole flight or anything like it outside of stunt flying.
I would presume almost any aircraft could do it with a skilled pilot under the right conditions. But I have no idea. I suppose it could be a test sequence to determine the planes reaction to changes in power output from the engines, but that’s just a WAG.
Generally maneuverabiity decreases to some degree with high altitude and low speed, all depending on the plane and a myriad of conditions.
Synchronizing that kind of thing sounds difficult. Everything done is synchronized formation is difficult.
I’m not really giving you much information, it’s pretty basic stuff about flight and there are a lot of exceptions to everything based on conditions. If you’re looking for something that would likely be described the way Arnold did, I don’t know what it is. I will just suggest that it’s the type of thing more likely to be done by small planes which can change speed and direction more readily than large ones.
IIRC, the U-2 did this in its original heyday - a long burn in a shallow semiballistic arc, then shut down and glide a few hundred miles to save fuel, repeat. It was part of what make Powers and the other pilots’ jobs so… interesting.
If Arnold had claimed to see a single object doing this, there seem to be any number of candidates. I can’t see a squadron of U-2s operating in long-range mode or tests of Loon missiles en echelon over Washington, though…