VTOL147
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VTOL Jet Engine Aircraft and VTOL Jet Engine

Wed Aug 07, 2019 1:31 pm

I am thinking about VTOL jet engine aircrafts like the following example (an ambulance).

Image

To be able to buid that kind of aircraft VTOL jet engines are needed. At the moment there are no VTOL jet engines available, but I have my own proposal:

Image

I have questions to jet engine experts. Is my design viable? Could the thrust-to-weight be over 50? What about a jet engine with following specs:

- thrust 8000 N (1800 lbf)

- weight 16 kg (35 lb), the thrust-to-weight ratio is 50

- height 300 mm (12")

- diameter 400 mm (16")

More: http://www.cyanspace.com/jetenginevtolaircraft.shtml
 
Woodreau
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Re: VTOL Jet Engine Aircraft and VTOL Jet Engine

Wed Aug 07, 2019 5:52 pm

Is this for a model airplane theoretical study or a demonstrator? I don’t see any viable medical aircraft that would be around 1800lb gtow. That is less weight than most automobiles.

The only VTOL aircraft I’m familiar with is an AV-8B aircraft that had a 105kN rolls Royce engine and a mtogw of 20,755lbs for a vertical takeoff.
Bonus animus sit, ab experientia. Quod salvatum fuerit de malis usu venit judicium.
 
VTOL147
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Re: VTOL Jet Engine Aircraft and VTOL Jet Engine

Thu Aug 08, 2019 6:16 am

This is just a theoretical study. If you look carefully enough, you can see four jet engines and of cource in the other side there are four more. This means 14.400 lb gtow. I think that it is enough for an ambulance but not for a Harrier.
 
ChrisKen
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Re: VTOL Jet Engine Aircraft and VTOL Jet Engine

Thu Aug 08, 2019 11:22 am

There's 4 jet engines? I see (via link as pics don't show) just the one (poss 2 if cutaway), with four nozzles either side which isn't the same thing.

I don't think your design as shown is viable. Even if you do finesse it somewhat, it's unlikely to be remotely practicable.

Much better off just sticking a rotor on top of it. More economical, quieter, less damage to surroundings (and patients!) and far more practical.
 
VTOL147
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Re: VTOL Jet Engine Aircraft and VTOL Jet Engine

Thu Aug 08, 2019 12:28 pm

There are 8 VTOL jet engines and one ordinary jet engine. I can see the pics just fine?

I am not necessary interested about the aircaraft. It is just an excample.

I just liked to know how viable is the VTOL jet engine design.
 
gloom
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Re: VTOL Jet Engine Aircraft and VTOL Jet Engine

Thu Aug 08, 2019 1:24 pm

I feel it would not be viable.
The first thing that worries me much is 8 engines, 8 possible points where something might go wrong. With one of engines damaged/shutdown, could be difficult to compensate, due to geometry, especially since you cannot compensate aerodynamically or with thrust vectoring.
There are also other considerations, while the engines are in the wingbox and four of them in line, it could be difficult to achieve desired construction strength.
Plus, I have no idea whether VTOL jet engine with such sizes could possibly be built. Typical engine arrangement (even with one spool and no bypass) needs to be quite long - you need at least some intake, compression, combustion chambers, turbine. All of them in 30cm length? While having 40cm diameter? I don't think that's even possible (not talking other words like efficient).

I think one jet engine as a propulsion, capable of generating a lift via ventilator (something similat to F35 VTOL, see: https://upload.wikimedia.org/wikipedia/ ... f_F-35.jpg). If you need, you can use 4 or 8 of them as well, with a smaller diameter, in any place. Still you'd need to consider stability in case one of them gets broken, but it's less likely than having a problem with complete engine.

Cheers,
Adam
 
VTOL147
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Re: VTOL Jet Engine Aircraft and VTOL Jet Engine

Thu Aug 08, 2019 2:38 pm

8 engines are for safety. One engine in every corner could be broken and takeoff or landing would still work.

The air intake would be in the aircraft like with fighters.

By the way can you see the pictures? If not here are the links:

http://www.cyanspace.com/images/vtolengine2.jpg
http://www.cyanspace.com/images/ambulance.jpg

In my jet engine design the idea is make it simple and light. That's why the burner is inside the compressor.

BR
Arto
 
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Starlionblue
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Re: VTOL Jet Engine Aircraft and VTOL Jet Engine

Thu Aug 08, 2019 2:55 pm

VTOL147 wrote:
8 engines are for safety. One engine in every corner could be broken and takeoff or landing would still work.

The air intake would be in the aircraft like with fighters.

By the way can you see the pictures? If not here are the links:

http://www.cyanspace.com/images/vtolengine2.jpg
http://www.cyanspace.com/images/ambulance.jpg

In my jet engine design the idea is make it simple and light. That's why the burner is inside the compressor.

BR
Arto


Serious question: Wouldn't it be simpler to have two larger engines thrusting centrally?
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
VTOL147
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Re: VTOL Jet Engine Aircraft and VTOL Jet Engine

Thu Aug 08, 2019 3:15 pm

With two engines it's not possible to keep the balance.
 
VTOL147
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Re: VTOL Jet Engine Aircraft and VTOL Jet Engine

Thu Aug 08, 2019 3:17 pm

I have checked the picture visibility. Firefox, Edge and Opera are not working, but Internet Explorer is working.
 
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Starlionblue
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Re: VTOL Jet Engine Aircraft and VTOL Jet Engine

Thu Aug 08, 2019 4:29 pm

VTOL147 wrote:
With two engines it's not possible to keep the balance.


Can't you duct some exhaust to the corners to keep balance in vertical flight? This seems simpler than adding 6 engines.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
VTOL147
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Re: VTOL Jet Engine Aircraft and VTOL Jet Engine

Fri Aug 09, 2019 3:43 am

VTOL fighters have one engine each end and pressured air is coming from wing tips. This works because the figters are usually very well balanced. Pressurised air needed mainly because of the wind.

My ambulance is another story it is not balanced. At least three engines is needed to balance it, but four is better and eight for safety.

Eight engines is not a problem. Even couple hundred dollars quadcopter can balance itself.
 
flipdewaf
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Re: VTOL Jet Engine Aircraft and VTOL Jet Engine

Fri Aug 09, 2019 4:24 am

VTOL147 wrote:
VTOL fighters have one engine each end and pressured air is coming from wing tips. This works because the figters are usually very well balanced. Pressurised air needed mainly because of the wind.

My ambulance is another story it is not balanced. At least three engines is needed to balance it, but four is better and eight for safety.

Eight engines is not a problem. Even couple hundred dollars quad copter can balance itself.


Instead of investing in 8 times as many engines as you need why not invest in making this aircraft balanced...?

You seem to be creating problems so that your creation is viable, at the scale you are proposing it is probably one of the few areas that an electric aircraft makes sense at the moment.

Fred
Image
 
VTOL147
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Re: VTOL Jet Engine Aircraft and VTOL Jet Engine

Fri Aug 09, 2019 7:33 am

Even the aircraft itself would be balanced, but cargo/people would make it unbalanced.
 
VTOL147
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Re: VTOL Jet Engine Aircraft and VTOL Jet Engine

Fri Aug 09, 2019 8:15 am

flipdewaf wrote:
VTOL147 wrote:
VTOL fighters have one engine each end and pressured air is coming from wing tips. This works because the figters are usually very well balanced. Pressurised air needed mainly because of the wind.

My ambulance is another story it is not balanced. At least three engines is needed to balance it, but four is better and eight for safety.

Eight engines is not a problem. Even couple hundred dollars quad copter can balance itself.


Instead of investing in 8 times as many engines as you need why not invest in making this aircraft balanced...?

You seem to be creating problems so that your creation is viable, at the scale you are proposing it is probably one of the few areas that an electric aircraft makes sense at the moment.

Fred


When VTOL fighters are build to day a lot of compromises are needed to do. If these jet engines would really exists, VTOL fighters would be standard issue rather than special case.
 
flipdewaf
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Re: VTOL Jet Engine Aircraft and VTOL Jet Engine

Fri Aug 09, 2019 8:56 am

VTOL147 wrote:
flipdewaf wrote:
VTOL147 wrote:
VTOL fighters have one engine each end and pressured air is coming from wing tips. This works because the figters are usually very well balanced. Pressurised air needed mainly because of the wind.

My ambulance is another story it is not balanced. At least three engines is needed to balance it, but four is better and eight for safety.

Eight engines is not a problem. Even couple hundred dollars quad copter can balance itself.


Instead of investing in 8 times as many engines as you need why not invest in making this aircraft balanced...?

You seem to be creating problems so that your creation is viable, at the scale you are proposing it is probably one of the few areas that an electric aircraft makes sense at the moment.

Fred


When VTOL fighters are build to day a lot of compromises are needed to do. If these jet engines would really exists, VTOL fighters would be standard issue rather than special case.

They are a special case as you need a lot of heavy equipment that eats in to useful payload and or capability that is often not worth the trade off of that added ability to perform different takeoff/landing manoeuvres. It’s a trade off.

Fred


Sent from my iPhone using Tapatalk
Image
 
VTOL147
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Re: VTOL Jet Engine Aircraft and VTOL Jet Engine

Sat Aug 10, 2019 7:28 am

VTOL147 wrote:


When VTOL fighters are build to day a lot of compromises are needed to do. If these jet engines would really exists, VTOL fighters would be standard issue rather than special case.


I just realised that, if VTOL fighters would be standard issue, aircraft carriers would be relics.
 
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Starlionblue
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Re: VTOL Jet Engine Aircraft and VTOL Jet Engine

Sat Aug 10, 2019 8:17 am

VTOL147 wrote:
VTOL147 wrote:


When VTOL fighters are build to day a lot of compromises are needed to do. If these jet engines would really exists, VTOL fighters would be standard issue rather than special case.


I just realised that, if VTOL fighters would be standard issue, aircraft carriers would be relics.


True. However, given the massive performance compromise involved in VTOL I don't think that's going to happen anytime soon.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo

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