Can a Vertical Jet Engine Replace Helicopter Blades for Hovering Crafts?

In summary, the conversation discusses the idea of using a hovering craft with a vertical jet engine instead of helicopter blades. The main concerns are the stability and control of the aircraft with a jet engine, as well as the added complexity and expense of such a design. The conversation also mentions the potential use of batteries and electric power for vertical takeoff and landing, and references examples such as the V-22 Osprey and AV-8B Harrier. Finally, the conversation touches on a specific aircraft design being developed by a company, which aims to achieve vertical takeoff with quad-copter rotors. However, there is skepticism about the effectiveness of this design and its current development stage.
  • #36
Given that a pulling engine is shooting hot exhaust at the payload, I assume that the original experimenters really were fooled about the stability, or they would have put the engine at the bottom.
 
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  • #37
hutchphd said:
I was going to make a (Boeing) comment about whether the X29 came with a software description manual but I won't because in fact Grumman built it ! I'll bet that thing would just uncork...but the F117 is unconditionally unstable too I believe
Instability is not uncommon in a modern fighter. In certain flight conditions, the F-16 is unstable. The flight control system is necessary to keep it flying. There are a lot of redundancies and safety checks built into its flight control.
 
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  • #38
pbuk said:
If it works, why isn't there a video of it working?

pbuk said:
However I was referring to the scam design presented in #7: I don't see any evidence that the fraudsters engineers have produced a working model that can VTOL, and there is no evidence of rotors on the images of N250UT.

pbuk said:
About as far as I am with my warp drive - look, here's a picture

Yes, I have a flying plane without the warp drive.

No s**t.
+1 on this. What I see in the photos is a funny-looking plane that looks like it was built on a helicopter body, and that's it. At first I was thinking the rotors might retract into the booms, but, as you say, if it works, just show a video of it working. So I would conclude as well that what we are seeing here is just marketing BS designed to hook investors. Right now it appears they are testing a short-range battery powered plane and that's it. Will they succeed in their ambitious plan of making it VTOL? Nobody has succeeded yet at either goal, but maybe they will be the first not to fail at both simultaneously?

As always the main issue with battery-powered aircraft is the weight of the batteries. For this 7,000 lb craft, more than half will need to be batteries. One wonders whether they'd be better off trying to prove the VTOL part can work by making an all gas or gas-electric version first.
 
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  • #39
berkeman said:
Source? It takes no effort for me to hold a stick in a vertical position with my fingertips. It takes constant concentration and feedback control for me to balance that same stick in the palm of my hand and keep it vertical...
The force vector from the hand points up, and not along the axis of the broomstick.
If the broomstick does tilt due to whatever reason ( try to place and balance of a stick on its end on a table and it will tilt and fall over ), the hand force vector still points up, providing a torque to the stick and the stick rotates more, To compensate you move the hand sideways in the direction of the tilt.

The rocket engine has its force vector 'always' pointing along the rocket axis and can never provides a torque to the rocket. Gravity cannot provide a torque since all parts of the rocket fall at the same rate ( ie are attracted to the Earth ) , including the engine.

Top or bottom engine amounts to the same thing.

try visualizing a rocket in space without air currents or air drag to see the effects of top-bottom engine behavior and determine if either would give different results.
 
  • #40
berkeman said:
Source? It takes no effort for me to hold a stick in a vertical position with my fingertips. It takes constant concentration and feedback control for me to balance that same stick in the palm of my hand and keep it vertical...
hutchphd said:
You are either embracing or dangerously flirting with the Rocket Pendulum Fallacy. The pendulum rocket fallacy is the incorrect idea that a top mounted rocket will make the vehicle more stable than a bottom mounted rocket. Robert Goddard's early "puller" rockets were not more stable than the later "pusher" ones. In either case it is the misaligned rocket that supplies unwanted torque, not gravity. Goddard clearly figured this out early.
As it happens, I visited the Smithsonian Air and Space Museum annex at Dulles, viewed a re-creation of his first rocket, explained why he designed it that way and explained fallacy to my friend this afternoon. Here it is:
https://en.wikipedia.org/wiki/Robert_H._Goddard#First_liquid-fueled_flight
https://en-academic.com/dic.nsf/enwiki/1272265

 
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  • #41
berkeman said:
How does it take off vertically?
After watching some videos: they are testing flight efficiency, VTOL configuration "will be tested later". Whatever it means.
 
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  • #42
What a coincidence. Beta Technologies is a local story for me. I'm posting right now 400m away from Beta's office/factory. They have certification for the aircraft, the factory, and the inspection techniques. My daughter tends the gardens of the Beta executives, and she promised to introduce me to them real soon now.

Like SpaceX, like Edison's power company, Beta's plans include the entire infrastructure, not just the aircraft. Infrastructure include recharging, maintenance and service facilities, and simulator training, manufacture of the body, batteries and control electronics. They are starting with local package delivery, and organ transplant delivery, but eventually their target it urban taxis.

This picture if from July 3. They did a flyby before the fireworks show in Burlington, VT.

1657196169371.png


This video let's you see more details of this very unique design. It is not easily comparable to anything else.
 
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  • #43
anorlunda said:
What a coincidence. Beta Technologies is a local story for me. I'm posting right now 400m away from Beta's office/factory. They have certification for the aircraft, the factory, and the inspection techniques. My daughter tends the gardens of the Beta executives, and she promised to introduce me to them real soon now.

Like SpaceX, like Edison's power company, Beta's plans include the entire infrastructure, not just the aircraft. Infrastructure include recharging, maintenance and service facilities, and simulator training, manufacture of the body, batteries and control electronics. They are starting with local package delivery, and organ transplant delivery, but eventually their target it urban taxis.

This picture if from July 3. They did a flyby before the fireworks show in Burlington, VT.

View attachment 303855

This video let's you see more details of this very unique design. It is not easily comparable to anything else.

I think that battery technology will make giant strides in the next couple of decades and battery-powered flight will benefit. The VTOL aspect has been actively pursued for a while.
 
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  • #45
Hornbein said:
Summary: Have a hovering craft powered by a jet engine.

Instead of helicopter blades have a vertical jet engine embedded in the craft. Steer via thrust vectoring.

The angular momentum of the jet engine might not provide enough stability but surely there is some way to get that.
Hi H,
There are jet engined helicopters, if that suits.
Camerart
 
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  • #46
It seems to me that because of the Goddard paradox the stability of would be the same if the blades were below the body. The stability of the rotor is due to its angular momentum, not from being above the body.

We can call this My Even Nuttier Helicopter Idea.
 
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  • #47
Hornbein said:
It seems to me that because of the Goddard paradox the stability of would be the same if the blades were below the body. The stability of the rotor is due to its angular momentum, not from being above the body.

We can call this My Even Nuttier Helicopter Idea.
Sounds more like a novel lawn mower.
 
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  • #48
Hornbein said:
Summary: Have a hovering craft powered by a jet engine.

Instead of helicopter blades have a vertical jet engine embedded in the craft. Steer via thrust vectoring.

The angular momentum of the jet engine might not provide enough stability but surely there is some way to get that.
it would work. it's just not better for now.
 
  • #49
Hornbein said:
It seems to me that because of the Goddard paradox the stability of would be the same if the blades were below the body. The stability of the rotor is due to its angular momentum, not from being above the body.

We can call this My Even Nuttier Helicopter Idea.
the reason that vehicles are more stable with the "foot" above the mass of the vehicle, is that when hanging, as long as upright is the most natural attitude, then the vehicle will default to upright, so stabilization can come in the form of "let gravity work". Whereas, with the thrust below the craft, the weight is going to droop from gravity, which will cause it to accelerate towards instead of away from the ground. So, helicopters can zero out from lots of positions, and then end up stable, because they hang from the thrust. But, rockets must actively posture no matter what, which is more difficult, and requires more accurate and precise control .
 
  • #50
tsmspace said:
the reason that vehicles are more stable with the "foot" above the mass of the vehicle, is that when hanging, as long as upright is the most natural attitude, then the vehicle will default to upright, so stabilization can come in the form of "let gravity work".
This is wrong: you have fallen victim of the pendulum fallacy.
 
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  • #52
tsmspace said:
the reason that vehicles are more stable with the "foot" above the mass of the vehicle
@tsmspace, perhaps you should read a thread in its entirety before responding. You are promoting an idea that has already been debunked in the thread.
 
  • #53
Jonathan Scott said:
Sounds more like a novel lawn mower.
Bring it up a bit and it becomes a haircutting machine that can service 2 to 3 persons at the same time. Bring it down a bit and it becomes a decapitator. A versatile tool for various types of occasions.
 
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  • #54
DennisN said:
Bring it down a bit and it becomes a decapitator. A versatile tool for various types of occasions.
It would be marvelous for crowd control.

Snow blowing might be another great application.
 
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  • #55
DennisN said:
Bring it up a bit and it becomes a haircutting machine that can service 2 to 3 persons at the same time.
The US Army played with this concept in the 1950s. Maybe they gave up because of too many close shaves?
avplatfm_01.jpg
avplatfm_02.jpg
 
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  • #56
The VZ-1 easy target? Looks legit to me
 
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<h2>1. Can a vertical jet engine provide enough lift for hovering?</h2><p>Yes, a vertical jet engine can provide enough lift for hovering. The force of the jet exhaust creates an upward thrust that can counteract the weight of the craft and keep it suspended in the air.</p><h2>2. How does a vertical jet engine differ from a traditional helicopter blade?</h2><p>A vertical jet engine uses jet propulsion to create lift, while a traditional helicopter blade uses rotary motion to generate lift. Additionally, a vertical jet engine can provide more precise control and maneuverability compared to helicopter blades.</p><h2>3. Are there any advantages to using a vertical jet engine over helicopter blades for hovering crafts?</h2><p>Yes, there are several advantages to using a vertical jet engine. It can provide more power and lift, allowing for larger and heavier crafts to hover. It also produces less noise and vibration, making it more suitable for urban environments.</p><h2>4. Are there any limitations to using a vertical jet engine for hovering?</h2><p>One limitation of using a vertical jet engine for hovering is its high fuel consumption. The constant use of jet propulsion requires a significant amount of fuel, making it less efficient for long periods of hovering compared to traditional helicopter blades.</p><h2>5. Can a vertical jet engine be used for both hovering and forward flight?</h2><p>Yes, a vertical jet engine can be used for both hovering and forward flight. It can tilt its exhaust nozzle to direct the thrust in different directions, allowing for both vertical and horizontal movement. This makes it a versatile option for various types of crafts.</p>

1. Can a vertical jet engine provide enough lift for hovering?

Yes, a vertical jet engine can provide enough lift for hovering. The force of the jet exhaust creates an upward thrust that can counteract the weight of the craft and keep it suspended in the air.

2. How does a vertical jet engine differ from a traditional helicopter blade?

A vertical jet engine uses jet propulsion to create lift, while a traditional helicopter blade uses rotary motion to generate lift. Additionally, a vertical jet engine can provide more precise control and maneuverability compared to helicopter blades.

3. Are there any advantages to using a vertical jet engine over helicopter blades for hovering crafts?

Yes, there are several advantages to using a vertical jet engine. It can provide more power and lift, allowing for larger and heavier crafts to hover. It also produces less noise and vibration, making it more suitable for urban environments.

4. Are there any limitations to using a vertical jet engine for hovering?

One limitation of using a vertical jet engine for hovering is its high fuel consumption. The constant use of jet propulsion requires a significant amount of fuel, making it less efficient for long periods of hovering compared to traditional helicopter blades.

5. Can a vertical jet engine be used for both hovering and forward flight?

Yes, a vertical jet engine can be used for both hovering and forward flight. It can tilt its exhaust nozzle to direct the thrust in different directions, allowing for both vertical and horizontal movement. This makes it a versatile option for various types of crafts.

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