Range finder for formation flights

[aek]

Hi,

Let's consider formation flighting. Not in an ICAO-defined formations, but of much closer, like that on aerobatic shows. That's very dangerous business so a proximity sensor of some kind is highly desired to facilitate collision avoidance in a manual or (more useful) automated way. I wonder what kind of range finding device will be more suitable for such applications.

Traditional technologies such as RADAR, DME/TACAN does not work well when the range is small. The speed of light is high so it's technically difficult (and by no mean cheap and precise) to measure a nanoseconds time of arrival interval that corresponds to a small distance. Moreover, a radar uses microwaves that has poor penetration capability so the risk of antenna shadowing in certain aircraft attitudes. So the need for multiple antennas that will complicate the setup further. The same is applicable to a lidar. And the whole interrogator-responder method (like in DME) usually provides the benefit only to the interrogator as the responder side remains not aware of the distance to the interrogator (let's keep TACAN aside). Also not good in that case.

And again, all that stuff is very complex. What is required is a device that combines the simplicity of ultrasound range finder and the advantages of RF carrier. I think there must be something because the radio navigation is not a new field and the major breakthroughs were made when the luxury of GHz computing power was not yet available so the only way was to apply a clever physics rather than a brute force. Seen a patents, research papers, DIY projects, but noting in a stores. Why?

[excrab]

Probably the answer to “why” is that if you need some sort of electronic thing to automatically stop you hitting another aircraft then you’re not experienced / skilled enough to be there in the first place (nor am I, btw).

[B2N2]

I think you need to keep your eye on the prize not on the instrument.

[safetypee]

The conventional method is optical. Human vision, mental computation, muscle activation.

If this skill demands more than can be expected, then full automation.
Partial systems have been used - military FD / radar for IMC refuelling.

For a full-up system, research unmanned aircraft, but even then I am not sure that full in-flight refuelling is automatic; the manned receiver manoeuvres relatively to the auto tanker.

Whatever sensor is used it must be capable of ’triangulation’, range alone is not enough to determine spatial position.

[DaveReidUK]

As expression involving a solution looking for a problem springs to mind.

[Bill Macgillivray]

Would this amazing piece of kit have to cover various formations, such as echelon, line astern, battle etc? What about formation changes with several a/c? How is it going to be presented? Sounds a bit pointless to me but, I am probably thinking in the past!!
Bill

[Arm out the window]

Visual cues, particularly triangulation with two sight lines (although more difficult in line abreast) are THE key to good station keeping.

A proximity sensor will just add a level of complexity and distract the pilot from what he or she should be doing, i.e. scanning the cues and continually adjusting. The only time I can see some artificial system being any good is if it was extremely accurate and fast acting, and linked to an autopilot system that would do the flying for you, which rather defeats the purpose!

[Intruder]

What is required is a device that combines the simplicity of ultrasound range finder and the advantages of RF carrier.
Yep! One pair of Mk 1 Mod 0 eyeballs! has worked well for formation pilots for 100 years or so...

[ShyTorque]

How about a bit of rope, tied between wingtips? Then again, it’s already been done.

[Runaway Gun]

Perhaps the original poster hasn’t been trained in formation flying, therefore doesn’t know how it works.

Knowledge dispels fear.

[finestkind]

Perhaps the original poster hasn’t been trained in formation flying, therefore doesn’t know how it works.

Knowledge dispels fear.

Tend to agree. I found instructing formation more difficult than aerobatic formation as the closer you where the easier the divergences where to pick up

[jimjim1]

Maybe have a look at how they do it with drones.

https://www.youtube.com/watch?v=44KvHwRHb3A
2,000+ (was it?) drones in formation.

https://www.ted.com/talks/vijay_kumar_robots_that_fly_and_cooperate
From 2012, at 8m 51s in to the video - describes formation flying

None of these go into the details but it might be a start.

Also -
https://verge.aero/everything-about-drone-light-shows
This suggests that in their displays each drone does it's own thing, in contrast to the description in the TED talk above which discusses the drones sensing each other.

[OldLurker]

In the TED talk there was little information about how the formation-flying drones relate to each other except a suggestion that each one 'senses' the proximity of its neighbours (didn't say how) and decides what to do to keep a proper distance: if that's all, there'd likely be a ripple effect which would cause the formation to wobble or 'hunt' around its desired flight-path, yet that doesn't seem to happen in the video.

In the video about drone light shows, there's no mention of proximity sensing: simply, each participating drone's flight path is set beforehand, the computer having worked out all the flight paths beforehand so as to create the desired effect without collisions.

Now try the swarming behaviour of animals – famously starlings ('murmurations') but also other birds, fish, insects, etc, which are able to fly or swim in thousands without collisions. Mk 1 eyeball for proximity detection, no doubt, but there's more to it than that. (Humans on the ground are bad at swarming, by the way – they bump into each other all the time.)

[OldLurker]

“Mk 1 eyeball” – nice phrase, but really it’s more like Mk 1,000,000 eyeball. Your highly sophisticated eye is the product of millennia of evolution. Mk 1 eyeball was very crude.
Just saying.

[Sleeve Wing]

Thanks, aek, for drawing attention to a skill that is becoming more commonly practiced.

>>> Let's consider formation flighting. Not in an ICAO-defined formations, but of much closer, like that on aerobatic shows. That's very dangerous business <<

It can be........ if it is not taught and practiced thoroughly. Its original concept was the passage of a number of aircraft together as a single unit. This was instead of the problems and increased collision risk of transitting each aircraft separately and trying to recontact just before reaching the combat area.

My feeling is that, if you need to consider other separators besides the Mk 1 eyeball, maybe you should leave it alone.

What would be your real reason for attempting it other than to try and emulate what you see at airshows ? Formation flying is not for "showing off". It is all to do with flying discipline and is a very skilled practice.

Having said that, there are a select number of clubs, schools and aircraft-specific groups that are available with very skilled instructors and very competent formation leaders in the UK should you wish to become further involved. Then you might see why a number of the thread contributors are uneasy about "autopilot formation", the complete antithesis of the reason for doing it in the first place.