Stratolaunch carrier plane, active vibration reduction?

[Spinnor]

Interesting new jet plane has rolled out of its hanger.

https://img.purch.com/h/1400/aHR0cDovL3d3dy5zcGFjZS5jb20vaW1hZ2VzL2kvMDAwLzA2Ni80NjMvb3JpZ2luYWwvZHJvbmUxX3dlYnNpdGUuanBnPzE0OTYyNjgyNTY=

It looks like there are vibration modes of the plane that during normal operation would shake the plane to bits. My guess is that there is some kind of computer controlled inputs to the control surfaces that can actively reduce vibration of the two fuselages relatively to each other? Your thoughts.

Thanks!

See, http://www.space.com/37046-stratolaunch-worlds-largest-airplane-first-rollout.html

 

[Mech_Engineer]

It looks like there are vibration modes of the plane that during normal operation would shake the plane to bits. My guess is that there is some kind of computer controlled inputs to the control surfaces that can actively reduce vibration of the two fuselages relatively to each other?

Sounds like speculation to me, got anything to back up your suspicions? I agree that the wing needs to be very strong to support such a large aircraft, but I'm guessing that's been considered? I'm not sure active damping of vibration via the plane's control surfaces would be necessary.

Twin-fuselage aircraft aren't very new, although this would be the biggest one ever made. See here: https://en.wikipedia.org/wiki/Twin-fuselage_aircraft

 

[berkeman]

http://www.space.com/37046-stratolaunch-worlds-largest-airplane-first-rollout.html

Wow, that is one ugly aircraft! Is the gap in the middle where they will mount the rocket to be launched?

EDIT -- And what are the black slots in the leading edge of the wings above the engine pods? Some kind of inlets for something?

 

[mfb]

Is the gap in the middle where they will mount the rocket to be launched?

Yes. It seems to miss the attachment points for the rocket unless they changed over time. https://commons.wikimedia.org/wiki/File:Stratolaunch-apogee.jpg.

No idea about the black slots.

The airplane probably has lower frequencies for various vibration modes involving motion of the fuselages, but that doesn't have to mean they are dangerous.

 

[berkeman]

No idea about the black slots.

Hmm, maybe it's only the paint scheme. In some drawings the leading wing edges look normal, and in this picture, it looks to just be paint...

https://i.ytimg.com/vi/UIZw6pXaXLg/maxresdefault.jpg

 

[russ_watters]

Wow, that is one ugly aircraft!

Rutan sure doesn't need to sign his "work"!

 

[Spinnor]

Sounds like speculation to me

I did say my guess %^) The inner wing does not look too strong compared to the size of the fuselages. I would have at least joined the rear elevators like the twin Mustang (turbulence from the payload might nix that idea, then just raise the elevator). That would have eliminated one vibrational mode and reduced another? The anticipated stress on that inner wing must be crazy?

Fly at late at night when the air is less turbulent?

 

[Mech_Engineer]

I do see what you're saying, I wonder if they're able to depend on the inherent strength of the composite construction? If design of other aircraft is any indicator, the wing is probably the most analyzed structure of the aircraft. Given that, I have to imagine the wing has gone through a very rigorous design review process before getting to the aircraft's build. It will be interesting to see if it has weird vibration modes on takeoff though...

 

[Spinnor]

Given that, I have to imagine the wing has gone through a very rigorous design review process before getting to the aircraft's build.

I agree, engineer's get it right way more often then they get it wrong and this type of design is not new.

The Stratolaunch just seems fragile to me. But it seems that the right supplemental inputs to the control surfaces could reduce stresses on the plane when inflight and might not be too hard to implement? Google does not turn up engineering details. I hope they are successful. Time to look into the sensitivity of inertial sensors.

 

[Dr.D]

As shown in the photograph, the wing is going to be subject to both bending and torsional vibration. That would make me very uneasy, but I do hope these fellows have worked through all of it with sufficient care.