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Asymmetric Aircraft

bigcalm

By bigcalm
in Science & Spaceflight

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mikegarrison

mikegarrison

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Posted (edited)

In general, unconventional airplane designs are either:

1) response to new materials that create a new optimum

2) response to unconventional mission requirements

3) attempt at creating an innovative solution to a common design problem

4) result of smoking too much dope

==============

Sometimes from the outside, it's hard to tell which one (or more) of those applies to any given design.

Edited by mikegarrison
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Nuke

Nuke

Posted
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  On 12/31/2017 at 4:39 PM, bigcalm said:

Lunacy like this.  I wouldn't even attempt it in KSP.

boomerang-bia.jpg

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the advantage of that design is the distace between the props is much smaller than typical twin engine craft (they even overlap a bit). so in the event of an engine going out you have much reduced induced yaw. it does require 3 axis trim to fly well though. oh and an old macbook in the copilot seat is used for its avionics. its actually pretty neat.

  On 12/31/2017 at 11:43 PM, mikegarrison said:

In general, unconventional airplane designs are either:

1) response to new materials that create a new optimum

2) response to unconventional mission requirements

3) attempt at creating an innovative solution to a common design problem

4) result of smoking too much dope

==============

Sometimes from the outside, it's hard to tell which one (or more) of those applies to any given design.

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in this case 3, though im sure 4 happened at least once. he designed this plane to get over the specific problem outlined above. 

 

Edited by Nuke
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magnemoe

magnemoe

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  On 1/1/2018 at 12:43 AM, Nuke said:

the advantage of that design is the distace between the props is much smaller than typical twin engine craft (they even overlap a bit). so in the event of an engine going out you have much reduced induced yaw. it does require 3 axis trim to fly well though. oh and an old macbook in the copilot seat is used for its avionics. its actually pretty neat.

in this case 3, though im sure 4 happened at least once. he designed this plane to get over the specific problem outlined above. 

 

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Yes and two engines adds a lot to flight safety, its often an requirement for many types of commercial flight and crossing water. 
Main issue is that its look kind of stupid and people don't like it, this is an issue for commercial aviation and cooperate planes. 

 

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mikegarrison

mikegarrison

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  On 1/1/2018 at 1:11 AM, magnemoe said:

Yes and two engines adds a lot to flight safety, its often an requirement for many types of commercial flight and crossing water. 

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That's arguable. Two engines means approximately twice the chance of failure, and if one fails the other is often in a non-symmetric location. That's the very issue that this plane is trying to overcome (according to Nuke; I'm not familiar with it myself). Of course, with only one engine, then an engine failure has its own set of consequences.

And there are situations where failure of the two engines is not independent -- running out of fuel for instance. Or flying through a rainstorm or a flock of geese. These can (and have) affect both engines just as if there had only been one engine.

There are a lot of tradeoffs between the number of engines and various design and regulatory issues. It's never quite as simple as "two is the best number of engines".

Edited by mikegarrison
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kerbiloid

kerbiloid

Posted
Posted (edited)
  On 12/31/2017 at 11:43 PM, mikegarrison said:

In general, unconventional airplane designs are either:

1) response to new materials that create a new optimum

2) response to unconventional mission requirements

3) attempt at creating an innovative solution to a common design problem

4) result of smoking too much dope

Expand  

5) attempt to rebalance the combobulated discombobulators by adding moar struts from the side to which it overturns

 

  Reveal hidden contents

 

  On 1/1/2018 at 12:43 AM, Nuke said:

he advantage of that design is the distace between the props is much smaller than typical twin engine craft (they even overlap a bit). so in the event of an engine going out you have much reduced induced yaw. it does require 3 axis trim to fly well though. oh and an old macbook in the copilot seat is used for its avionics. its actually pretty neat.

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So, either a miscarriage of this

  Reveal hidden contents

, or not enough money for aluminium, "try the demo-version".

 

  On 1/1/2018 at 1:18 AM, mikegarrison said:

Two engines means approximately twice the chance of failure, and if one fails the other is often in a non-symmetric location.

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and the wider it is, the more asymmetric it gets.
Not sure if it was easier to land on such Batman-plane with a single engine survived rather than switching it off.

Edited by kerbiloid
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PB666

PB666

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  On 12/31/2017 at 9:48 PM, DDE said:

Everyone calm down!

%D0%BF%D0%B7%D0%BC.jpg

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I actually used a trencher, got a big long scar on my leg to prove it, lol.

  On 1/1/2018 at 12:43 AM, Nuke said:

the advantage of that design is the distace between the props is much smaller than typical twin engine craft (they even overlap a bit). so in the event of an engine going out you have much reduced induced yaw. it does require 3 axis trim to fly well though. oh and an old macbook in the copilot seat is used for its avionics. its actually pretty neat.

Expand  

I will take the increased yaw. The only time yaw is really important is on take-off, on landing the engines are down throttled anyway so.

That plane was probably designed by an engineer who got drunk in a bar, made a bet with hits engineer friends and then had to prove he could do it.

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Green Baron

Green Baron

Posted
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  On 1/1/2018 at 1:18 AM, mikegarrison said:

That's arguable. Two engines means approximately twice the chance of failure, and if one fails the other is often in a non-symmetric location. That's the very issue that this plane is trying to overcome (according to Nuke; I'm not familiar with it myself). Of course, with only one engine, then an engine failure has its own set of consequences.

And there are situations where failure of the two engines is not independent -- running out of fuel for instance. Or flying through a rainstorm or a flock of geese. These can (and have) affect both engines just as if there had only been one engine.

There are a lot of tradeoffs between the number of engines and various design and regulatory issues. It's never quite as simple as "two is the best number of engines".

Expand  

To summarize: what is the second engine on a two engine aircraft for ? It takes you to the crash site ....

Yeah, that's an old one.

 

I like the asymmetric designs :-)

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Starman4308

Starman4308

Posted
Posted (edited)
  On 1/1/2018 at 1:18 AM, mikegarrison said:

That's arguable. Two engines means approximately twice the chance of failure, and if one fails the other is often in a non-symmetric location. That's the very issue that this plane is trying to overcome (according to Nuke; I'm not familiar with it myself). Of course, with only one engine, then an engine failure has its own set of consequences.

And there are situations where failure of the two engines is not independent -- running out of fuel for instance. Or flying through a rainstorm or a flock of geese. These can (and have) affect both engines just as if there had only been one engine.

There are a lot of tradeoffs between the number of engines and various design and regulatory issues. It's never quite as simple as "two is the best number of engines".

Expand  

Approximately twice the chance of a single engine failure, yes, but not total engine failure. My understanding is that most 2-engine birds can fly on one, at the cost of being difficult to fly and running the other engine close to its limits, which can cause that one to fail too.

Still, you reduce the risk of your plane becoming a glider significantly, making an engine-out event much less likely to cause a total failure. There is an increase in some risks such as "lol, engine exploded and now you have no left wing", but I suspect multi engine birds are generally safer than single engine. Maybe not as efficient or effective in some cases, but multiple engines are probably in general safer than one.

I heard this one story about an Air Force F-16 pilot getting impatient at traffic control because they prioritized a B-52 running the dreaded 7-engine-landing over his single engine that was acting "peaky".

Edited by Starman4308
Autocorrect I have no idea
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DDE

DDE

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  On 1/1/2018 at 6:17 PM, Starman4308 said:

There is an increase in some risks such as "lol, engine exploded and now you have no left wing", but I suspect multi engine birds are generally safer than single engine. Maybe not as efficient or effective in some cases, but multiple engines are probably in general safer than one.

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The borderline absence of military helicopters with one engine - as opposed to two-three - seems to confirm it.

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PB666

PB666

Posted
Posted
  On 1/1/2018 at 6:17 PM, Starman4308 said:

Approximately twice the chance of a single engine failure, yes, but not total engine failure. My understanding is that most 2-engine birds can fly on one, at the cost of being difficult to fly and running the other engine close to its limits, which can cause that one to fail too.

Still, you reduce the risk of your plane becoming a glider significantly, making an engine-out event much less likely to cause a total failure. There is an increase in some risks such as "lol, engine exploded and now you have no left wing", but I suspect multi engine birds are generally safer than single engine. Maybe not as efficient or effective in some cases, but multiple engines are probably in general safer than one.

I heard this one story about an Air Force F-16 pilot getting impatient at traffic control because they prioritized a B-52 running the dreaded 7-engine-landing over his single engine that was acting "peaky".

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It really depends on the load, if your close the end of the flight and your load is light, you can go down to the 2000 ft limit and increase performance markedy (unless you happen to live in Denver, in which case find a herd of buffalo and straif them.

If you lose an engine on a two engine craft on takeoff at full load, of course you better hope it happens before V1 But again the Concorde had four engines which went to 3 then 2 so . . . . . My favorite piston prop is the DC7, I don't have a favorite jet. But the 747 can easily make home on 3 engines and I think the 777 has about 1000 miles on ETOPs so . . . . . . . I would fly in a twin prop over a single prop anyday, that is to say that I will never fly in a single prop. They should probably be banned except the very low end stuff. I should also point out that a fair amount of crashes in dual props occur because the pilot left his fuel at that departure airport. There's no fixing stupid.

We also need to have some perspective here, because some of you kiddies don't know your history.

The DC3 was first produced in 1935 as a twin engine tail-dragger. The seems to be pejorative except for the fact that after cancellation of production in 1942 . . . . . . 76 years ago (ahem when you have 76 years you can talk trash) there are 2000 DC3s still in active service. If you need something that the DC-3 does you don't complain about the little tiny wheel on the back. Some of these little, literally, flying antiques in their day were ferrying their loads to common everyday places like the South Pole during ever so slightly abnormal Southern Winter. The advantage it has over turbo props (which DC3 can be retroed with) is that the petro that DC3 can use does not freeze at as high a temperature as jet fuel.

  Quote

"the only replacement for a DC-3 is another DC-3". from good ole wikipedia

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Here one of the power plants for the DC-3

450px-R-1830_IWM.JPG

The name plate is Pratt& Witney but Wright also dabbled in DC-3 engines

450px-Wright_R-1820_G.jpg

Courtesy of Wikipedia.

 

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Shpaget

Shpaget

Posted
Posted
  On 1/1/2018 at 6:17 PM, Starman4308 said:

I heard this one story about an Air Force F-16 pilot getting impatient at traffic control because they prioritized a B-52 running the dreaded 7-engine-landing over his single engine that was acting "peaky".

Expand  

I've heard that one too.

In any case, if I have to choose between being on a plane with one or two engines when one fails, I'll take an engine failure on a two engine plane any day.

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