Topic: Anyone tried this Honda???

[754]

Anyone get nearto, in , or had a ride in the Honda Jet??

[droopy]

no not yet looks cool  for a small jet  
BTW for those of you that don't know about this subject here's
a link 
https://hondajet.honda.com/default.aspx?bhcp=1

[Bob Wessner]

Looks cool, but what are the advantages of this design vs having the engine pods attached to rear body, as they are on some, for example?

[Bodi]

There's a link to a technical paper about the engine location. The basicdesign  goal is to have more cabin room, of course: the structure and plumbing for the engine mounting takes up a lot of space in the rear of the cabin with the fuselage mounting. Maybe it will be quieter too - I've sat in the back of many DC-8 type aircaft and the noise from the engines is unpleasant. I'm not in the Gulfstream social class.
The technical stuff is pretty intense, but I read it as saying the over-wing mount is actually more efficient than a clean wing. The reasons are beyond my understanding. Perhaps it will make sense to you... http://hondajet.honda.com/pdf/tech_papers/Journal_of_Aircraft_Vol40_No6_P1177_P1184_Wave_Drag_OTWEM.pdf

[Bob Wessner]

Thanks, I wondered about the noise, as in reduction, issue.

[gerhed]

I wonder if when the chain breaks the crankcase gets holed ?

[Bob Wessner]

No, but they are still debating which oil to use.

[754]

is it called K0 or perhaps J0     

[mattcb350f]

the Fokker 614 had that design back in the 60's. I guess Honda figures they were onto something.

the problem with the traditional location of the engines; at the back of a fuselage for a "Lear Jet" is that in the event of a stall, the aircraft becomes almost uncontrolable and falls a$$ first out of the sky. so putting the engines on the wings would fix this problem.

Don't worry though, todays fly by wire systems are designed not to let them stall... but the danger is still there.

 Matt.

[azuredesign]

the Fokker 614 had that design back in the 60's. I guess Honda figures they were onto something.

the problem with the traditional location of the engines; at the back of a fuselage for a "Lear Jet" is that in the event of a stall, the aircraft becomes almost uncontrolable and falls a$$ first out of the sky. so putting the engines on the wings would fix this problem.

Don't worry though, todays fly by wire systems are designed not to let them stall... but the danger is still there.

 Matt.

Matt, isn't the primary concern for isolating the engines from the control surfaces, to minimize turbulance and decrease stall potential? Keeping turbulant airflow off the wings and tail is paramount from my understanding. Having the moment of inertia centered so that the plane is balanced is also very important as well, but isn't this usually handled by seat and luggage placement?

I'm not an engineer, let alone an aeronotics engineer, but am fairly certain that the engines need to mount on a rigid portion of the airframe for efficiency. With carbon fiber , the wing

[azuredesign]

Hmm, my elbow hit the mouse and my computer hit the post button!

Matt, isn't the primary concern for isolating the engines from the control surfaces, to minimize turbulence and decrease stall potential? Keeping turbulent airflow off the wings and tail is paramount from my understanding. Having the moment of inertia centered so that the plane is balanced is also very important as well, but isn't this usually handled by seat and luggage placement etc?

I'm not an engineer, let alone an aeronautical engineer, but am fairly certain that the engines need to mount on a rigid portion of the airframe for efficiency. With carbon fiber , the wing

The wing should be more rigid with carbon fiber, especially when mounted close to the fusilage. One question then becomes how far out laterally can you place the engines so as to not affect the control surfaces on the tail? Also, it seems like the engines themselves will cause some turbulence over the wing.

Must be fun to be an engineer!

[mattcb350f]

Well, looking at the plane I would say that the tail is high enough that the thrust from the engines should never affect the elevator control surface. However, keeping the thrust air off the wing is not always paramount. look at prop driven planes. there always flying in prop wash which actualy helps lift. Your right though, isolating the engines and thrust allows for smoother flow over the wing and fuselage which inturn lowers drag. hence better efficiency.

One thing I've noticed in looking at this plane is that the pylons for the engines are attached to the wing, aft of the midpoint. I bet this is where they've got rid of drag from the pylons. On a wing, the air only really stays attached to it on the top side till about 50% of the chord length, or half way back. After that, the air begins to seperate and become turbulant and this is where a lot of drag comes from. By mounting the pylons in an area of the plane that has turbulent air anyway, maybe there's less drag on the pylon itself.

Matt.

[Tim.]

I'd tend to think seperating the engines from the fusalage would allow for future changes to engine specification/design without changing the fusalage design.  Honda effeciency.

[azuredesign]

look at prop driven planes. there always flying in prop wash which actualy helps lift. Your right though, isolating the engines and thrust allows for smoother flow over the wing and fuselage which inturn lowers drag. hence better efficiency.

One thing I've noticed in looking at this plane is that the pylons for the engines are attached to the wing, aft of the midpoint. I bet this is where they've got rid of drag from the pylons. On a wing, the air only really stays attached to it on the top side till about 50% of the chord length, or half way back. After that, the air begins to seperate and become turbulant and this is where a lot of drag comes from. By mounting the pylons in an area of the plane that has turbulent air anyway, maybe there's less drag on the pylon itself.

Matt.

Hi Matt,

I'm pretty sure that the rational for both the turbulence on the back portion  of the upper wing surface and for the positioning of internal combustion engines is similar. That is if I remember any of the ground school stuff I learned! A prop driven plane pushes air under the wing creating a faster flow under the wing than above it. This creates negative pressure above the wing allowing lift. Turbulence on the aft part of the wings upper surface effective slows the flow of air over the upper suface which also contributes to the same situation.  Noting that the aft control surfaces are mounted fairly high was a good observation, I didn't see that. Thanks for thinking with me!

[BobbyR]

It reminds me of a pretty A10 Warhog. Very stable and nimble craft. Maybe the CB750 of personal jets. 

[mattcb350f]

A prop driven plane pushes air under the wing creating a faster flow under the wing than above it. This creates negative pressure above the wing allowing lift.

You've kind of got it right.. except the air flows faster over the top part of the wing 
Bernoulli's equation states that all pressure; dynamic and static in a given system must equal a constant. Basically, when the air flows over the top of the wing, the dynamic pressure is increased and thus the static pressure is decreased creating an area of lower pressure. The wing then tries to move towards this area of low pressure and this is lift. But the problem engineers have always had is trying to keep the air stuck to the wing, in whats know as the boundary layer. Boundary layer seperation happens from about 30% back from the leading edge to up to 50% back, depending on the wing shape and velocity. When this occurs, the airflow becomes turbulent and creates drag. This happens to some extent on all airfoils and a "stall" is actually caused by complete boundary layer seperation on top of the wing.

.... Well this thread sort of wondered off into aerodynamic theory 

Matt.

[azuredesign]

A prop driven plane pushes air under the wing creating a faster flow under the wing than above it. This creates negative pressure above the wing allowing lift.

You've kind of got it right.. except the air flows faster over the top part of the wing 
Bernoulli's equation states that all pressure; dynamic and static in a given system must equal a constant. Basically, when the air flows over the top of the wing, the dynamic pressure is increased and thus the static pressure is decreased creating an area of lower pressure. The wing then tries to move towards this area of low pressure and this is lift. But the problem engineers have always had is trying to keep the air stuck to the wing, in whats know as the boundary layer. Boundary layer seperation happens from about 30% back from the leading edge to up to 50% back, depending on the wing shape and velocity. When this occurs, the airflow becomes turbulent and creates drag. This happens to some extent on all airfoils and a "stall" is actually caused by complete boundary layer seperation on top of the wing.

.... Well this thread sort of wondered off into aerodynamic theory 

Matt.

Thanks Matt!
I'll have to do a little boning up.