Jet pack flight.

[planedriver]

 

[kgwilson]

You wouldn't want to be up for long with that system as you are holding your body weight and that of the jetpack with your arms.

[old man emu]

I don't think that those things on his arms are anything to do with the actual thrust. If you look closely at the ground, the grass is not flattened in front of him, only behind. Also, as he waves his arms around, his body is not pushed in the opposite direction. When in the air, his arms are in different positions in relation to his body, but he flies straight. It seems that the turn is made by weight shift.

[onetrack]

He has two small thrusters on each arm and two larger ones on his back. As I understand the design, the thrusters on his arms are needed to balance the thrust from the backpack jets.

Because the backpack jets are larger, they are providing the larger amount of thrust for forward movement. However, I have to agree with KGW, your arms are still going to rapidly get tired, having to hold them out straight for an extended period, against the thrust pressure.  They're pretty coy on showing how he landed, or how he went with extended flight.

 

The Americans had short-run jet packs that ran on rocket propulsion fuel in the 1950's. They were designed and manufactured by Bell for a military contract that sought to define the viability of jet packs.

But the military gave up, when it was realised that rocket propellants only allowed short periods of use before the fuel ran out.

Small jets obviously provide more controllable thrust with lighter weight - and todays electronics have vastly improved control mechanisms. But the basic instability of jet packs remains, along with the quite limited range.

And of course, no-one has come up with any satisfactory injury or fatality prevention method, if the thrust fails rapidly. I think that's what jet pack designers need to be concentrating on.

 

https://mashable.com/video/jet-packs-army-bell/

Edited September 29, 2020 by onetrack

[old man emu]

I don't think that a ballistic chute would be a life saver as these things are only meant to operate to just above tree-top level at best. The biggest draw-back is the lack of range. While very good in the thrust/rate ratio, the fuel consumption makes them ineffective for anything other than short hops. I doubt if even an electric fan jet as used in RC planes would make this type of machine practicable.

 

[red750]

Whatever happened to New Zealand's Martin Jetpack?

 

[onetrack]

The designer is intent on getting his jet pack out into the real world. Here's an ABC article showing how he uses it to speed up urgent medical help, to an "injured" climber, in a rescue exercise.

 

https://www.abc.net.au/news/2020-09-30/english-paramedics-trial-jet-suit-in-lake-district/12718122

[440032]

Martin Jetpack, which was neither a jet nor a pack! Geeze, even John Robinson was flying a jetpack in Lost in Space in the 60's!

 

Follow Australian HELIJEN and the Jetsuit development.

https://www.helijen.com/

 

 

[red750]

Stephen Colbert played t he video in Onetrack's video above. His comment --  Not powerful enough to fly you out, but one of the coolest things you'll see, as you pass away.

[old man emu]

On 30/09/2020 at 10:55 AM, red750 said:

Whatever happened to New Zealand's Martin Jetpack?

The Company crashed and burned in 2019.

https://www.nzherald.co.nz/business/news/article.cfm?c_id=3&objectid=12231984

[onetrack]

The Rotron RT1200 Engine, a product of British adventurer/entrepeneur Gilo Cardozo, was a particularly poor choice for the Martin Jetpack.

 

The UAV engine maker makes some exceptional claims about its engines, but their engines are obviously high-power, short-life engines, and purchased by Defence Depts who care little about the short life of what they buy.

 

The basic problem with the Rotron engines is they utilise the Wankel Rotary design, which they have taken to extreme limits by way of power output and light weight.

 

In other words, they sacrifice durability for extremely high power output and light weight. The best example of throwaway engine technology you could hope to find. The RT1200 engine had a lifespan of 30 hrs in the Martin Jetpack.

 

https://www.unmannedsystemstechnology.com/tag/rotron-power-ltd/

[HeliJen]

Thanks @440032 (I found this page through traffic to my site :)).  

 

Well, you're all right in parts of your statements:-

 

1. @kgwilson: bearing the thrust through your arms does require a level of fitness that a non-athlete / exercise-phobe like myself will suffer with.  Given I'll be flying a version of it across Australia, it's a problem worth solving, and my iJETPACK team are onto it.

 

2. @onetrack: correct - the arms produce up to ~44kg thrust each, while the back produces ~55kg thrust, enabling a stable tripod effect with natural forward motion due the additional back thrust.  Moving your arms changes the thrust vector, resulting in direction control (yaw, fore/aft, climb/descend and combinations of).  Obviously changing your back position affects direction too.

 

Re the 50s version ('RocketBelt'): my chief engineer built and flew (still flies) Australia's first and only RocketBelt, and yes, one of its many challenges is its very limited fuel (hydrogen peroxide) endurance at just ~20 seconds.  But like all early inventions, it played an assistive role in the emergence of the turbine powered jetpacks, which still aren't great with 8-10 mins on Jetpack and 3-5 mins on Jetsuit.  I have my team looking into ways to address this for the World Record, but it's a tough one to solve as even with thrust to allow a greater payload, there's the physical limitation of carrying large amounts of fuel (though only a real issue for pre-takeoff - in flight you don't feel it, and post-flight you're back to empty weight).

 

"instability of jet packs": not sure what you mean here. The Jetsuit is quite stable from a control perspective (the Jetpack not as much so -- think unicycle vs tricycle in terms of C.of.G challenges); and its turbines are not immensely different to helicopter turbines (albeit smaller with more frequent maintenance requirements).

 

"injury or fatality prevention method": totally agree that this is a weakness compared to other aircraft.  Though as @old man emusays, it is flown at low heights to reduce this risk.  We are working on a redundancy system and are investigating alternative methods of safety in suits and ballistic parachutes.  We'll make improvements but don't expect to fully resolve the issue in 2021 (at least not in readiness for the World Record attempt).

 

3. @old man emu: yeah, electric fans aren't up to it yet.  There are a lot of people trying to solve the multi-billion dollar problem of battery weight.  Once this happens, the game changes completely.  Looking forward to that day.

 

4. @red750: the benefit of the Jetsuit is to have first response there at speed.  It can also get into far more confined spaces than helicopter can.  Jetpack Aviation's forthcoming Speeder (flying motorbike) is a far better solution as it is autonomous (optionally piloted), not much larger than a superbike (still can get into confined areas) and can therefore have a paramedic on one, and an empty one flying beside to stretch the patient back to the ambulance.  First working prototype is due early 2021.

 

5. Martin Jet-not-jet-pack: love that they tried.  Was never a fan ('scuse the pun) of the form factor.  But again, we can all learn something from every attempt at innovation, successful or not. 

 

As for us, we're in build at the moment, on track for a first test-flight in Feb.  Can wait to get back in the air.  Flying these things is a feeling like no other! 

 

Jen :)