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Now this looks interesting... (Jetson 1)

Clipperstorch wrote:

With a lot more endurance this could be a nice tool for a helicopter cowboy.

Unfortunately given the battery technology available today and in the foreseeable future on one side and the physics of rotorcraft flying on the other side, with these kinds of small rotor helicopters you pretty quickly get to the point that adding additional battery capacity (and hence more weight) will actually reduce endurance rather than increase it

Germany

Actually what is the advantage of all those tiny rotors compared to a traditional helicopter powered by an electric motor? There seemed to be an electric Robinson prototype and then you can buy most of the components from the shelf with existing certification. It can autorotate even if all electrics fail and there are plenty of pilots with existing training who just need differences training for another power plant. Performance is not great but so far nobody did show that those multicopters are more performant or less noisy or am I wrong?

www.ing-golze.de
EDAZ

Malibuflyer wrote:

with these kinds of small rotor helicopters you pretty quickly get to the point that adding additional battery capacity (and hence more weight) will actually reduce endurance rather than increase it

They aren’t very efficient to start with: they literally brute-force themselves into the air. Lots of small fixed pitch rotors is a lot less efficient than one larger variable pitch rotor, and helicopters are already inefficient. These kind of multirotor drone-like machines are worse.

With drones you can get away with it because for something that weighs 5kg, it’s not hard to have an absurd power to weight ratio (and the same is true with RC helicopters, which will run rings around any similar-sized drone). But it doesn’t really scale very well.

Andreas IOM

Sebastian_G wrote:

Actually what is the advantage of all those tiny rotors compared to a traditional helicopter powered by an electric motor?

The “drone” type needs a lot less space to take off and land. It also appears to be easier to fly (as almost all of it is computer supported) and quite possibly a lot cheaper to maintain, particularly if they can mass produce the rotors to an extent that changing one is a relatively benign exercise. Helo rotors are viciously expensive and quite often Robinsons and other light helos are thrown away (sold as project for no money) once the rotors expire.

rotors on this kind of contraptions also rarely appear to have variable pitch and the associated controls… so they are basically horizontally mounted cessna 150 props, which I suppose makes them a lot cheaper to produce and replace than any helo rotor could ever be.

What i’ve been wondering looking at those things is why they are not moving into the direction of ducted fans. IMHO this would, particularly for human application, increase safety notably while possibly opening the way for thrust vector control as well as increase of thrust due to channeling of the airflow.

Last Edited by Mooney_Driver at 30 Nov 21:09
LSZH, Switzerland

Sebastian_G wrote:

Actually what is the advantage of all those tiny rotors compared to a traditional helicopter powered by an electric motor? There seemed to be an electric Robinson prototype and then you can buy most of the components from the shelf with existing certification. It can autorotate even if all electrics fail and there are plenty of pilots with existing training who just need differences training for another power plant. Performance is not great but so far nobody did show that those multicopters are more performant or less noisy or am I wrong?

No, they’re terrible from an efficiency standpoint. An electric helicopter would be much, much more efficient. The bigger the rotor, the more efficient it gets. But, these have the advantage of being able to use off-the-shelf RC and drone motors and props, so that’s the appeal. And they have low inertia, so can change rpm really quickly, which is an advantage for quick maneuvering.

Heck, I’d love to have one in my backyard here, zoom over to the airport in 15 mins and fly over all that traffic jammed up. Be amazing.

https://elib.dlr.de/111091/1/DLRK%20Paper_2016_Strickert_Faktencheck_Multikopter.pdf
local copy

Unfortunately in German but it answers all our questions. Short summary is multicopters have far inferior performance to helicopters especially at speed. All those evtol start ups should read this…

So probably something like this will work much better than the multicopter advertized above:



www.ing-golze.de
EDAZ

Sebastian_G wrote:

Short summary is multicopters have far inferior performance to helicopters especially at speed. All those evtol start ups should read this…

The question is mission.

Helicopters, particularly for private use, need by comparison rather large fields to operate from. With a rotor diameter of 8-12m and the tail going beyond that, the minimum size of a heliport is in the 20×20m area. With approach and take off area to stay free of obstacles, most backyards are way too small to accommodate helicopters, you’d need at least a 100×20m area to be halfways safe. Add to that: To become a helo pilot, let alone be able to land in your backyard requires a lot of training and is quite expensive. Helos are also quite difficult to fly with precision and quite accident prone trying to land in tight spots.

The aim of devices like the Jetson is to be able to operate from your driveway or backyard, if possible without or with a much reduced pilots license. They are a Swedish company and their marketing goes clearly into that direction, they even claim you don’t need any license to fly it. They have apparently sold all their 2022 and most of the 2023 production, some of which to Germany and Switzerland by the looks, but predominantly to the US.

So efficiency is the least thing on their minds, they actually limit speed artificially to 100km/h. It clearly is positioned as a personal areal vehicle, the dream of the “air car” or as a german paper calls it “flying motorcycle”. I can’t help thinking of the French story of the “Curé volant” where a local pastor uses his VeloSolex fuelled by Absynthe to fly between his house and his flock. With a size of 2.4 × 2.8 m and heavily computerized flying controls, it is clear that the idea is to fly out of practically anywhere, a 4×4m area should be sufficient, but even 10×10m is feasible for most backyards. A long way away from a helo. Also noise will be much less than any helo. As @AdamFrisch sais: this is the flying bicycle to zoom from your back garden to the airport and back or to load into the back of your truck and fly around at your heart’s desire. And in some parts of the world this may well work. With 20 mins “endurance” and 100 km/h limit, this means a useful range of roughly 33 km to “empty tanks” and therefore a radius of about 25 km where one can usefully fly.

Of course in the heavily regulated parts of Europe this kind of idea will not be of any practical use. In our overcrowded envy and NIMBY ridden society, this kind of tool has no chance to ever be allowed to use in any meaningful way imho. I would say the two who ordered this thing in Switzerland and Germany will find that their neighbours will be up in arms if not shotguns if you try to fly that locally. And their reaction is probably nothing against what the usual suspects of regulators will have to say to this kind of contraption. If you just google the Jetson, it is “funny” to see how German, Austrian and Swiss newpapers smash this thing as “rich boys toy” and predict failure on a huge base, while Top Gear and non-german press is much more enthusiastic.

So in the US, Canada or Australia, where there is plenty of space, possibly in Eastern Europe, where flying is much more accepted, possibly in the UK, France, where the ULM scene is thriving, things may look very differently indeed.

Last Edited by Mooney_Driver at 01 Dec 06:14
LSZH, Switzerland

Mooney_Driver wrote:

So in the US, Canada or Australia, where there is plenty of space, possibly in Eastern Europe, where flying is much more accepted, possibly in the UK, France, where the ULM scene is thriving, things may look very differently indeed.

But the regulation still needs to change. The Jetson is clearly an Annex I aircraft, but even so is there any European country that currently would allow this thing to be flown without a license and below 500 ft?

ESKC (Uppsala/Sundbro), Sweden

Airborne_Again wrote:

The Jetson is clearly an Annex I aircraft, but even so is there any European country that currently would allow this thing to be flown without a license and below 500 ft?

Exactly that is what I am wondering about. Jetson claim you can fly this thing without a license. I call this marketing b.s, but seeing that several press reviews are talking of “limitations” which allow flying without a license, I really don’t know what they are talking about. I opened a new thread for this issue as I think it is more general than just this device.

LSZH, Switzerland

Sebastian_G wrote:

Actually what is the advantage of all those tiny rotors compared to a traditional helicopter powered by an electric motor?

There are actually a couple:
- You can use higher rotation speeds w/o getting supersonic effects at the blade tips. So you don’t need a gearbox.
- Multicopter has intrinsic redundancy → catastrophic failure of a single rotor does not lead to a crash
- Smaller rotors have less inertia – therefore one can regulate the rotor speed better
- lower forces on each rotor, shafts, etc. that enables simpler construction

Germany
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