Ginormous XB-70 Valkyrie Project - Part 4 (Flight)

by FliteTest | June 8, 2018 | (6) Posted in Projects

Ben Harber's epic FT sponsored build project reaches new heights with an epic conclusion.

If you're not aware, community member Ben Harber started a gigantic XB-70 Valkyrie build late last year. The project has experienced a few ups and downs, but recently the huge model airplane took flight for the first (and only) time. To appreciate the full the story, let's take it back a few months. 


V1 Disaster 

It's February 2018, and Ben has just finished his brand new, gleaming white Valkyrie. The weather is looking good and everything seems good to go. Time to take the bird out for an inaugural test flight. 


Ben and his team made use of a dedicated tent on site to prepare the brand new aircraft for flight. 


All systems were checked over, including the retractable landing gear and gear doors. As a complicated machine, all of these functions needed to be working just right. 


The model included multiple hatches for the main batteries, receiver and FPV transmitter. 


Once everything was ready to go, Ben and his father laid the aircraft on the tarmac ready to be taxied into position. 


The crescendo had reached boiling point. This was it, the moment that months of work had led up to. Six EDFs, throttle open, let's go. 


Disaster. Out of control, the huge model went off course and smashed into a perimeter fence. Thankfully, no one was hurt. However, the Valkyrie was written off in an accident that will likely be remembered for a very long time. 


Onboard cameras captured the drematic moment when the Valkyrie left the tarmac and veered sideways onto the gravel. The impact was unforgiving. 


Back at base camp, the splintered foam board and twisted wings were assessed whilst everyone caught their breath. Like all good pilots, Ben put a positive spin on things. 'Well, I can now build three more of these' he said pointing at his F-4


If you want to see Ben's vlogs on his experience through the V1 build, testing and aftermath of the incident, here's a playlist link


Version 2 Takes Shape

The story didn't end with the crash of Ben's beautiful model. A V2 was to be built!  Starting with the vertical stabilisers, progress was made quickly.


Here's the inside of the wing, specifically at the folding wingtip section. This 3D printed hinge allows the whole outer section of the Valkrie's wing to fold down just like the real thing. 


As you can see, the wing structure is fairly complicated. This really is necessary for a model of this size to retain structural cohesion whilst in the air. 


The canard flaps are fully functional and are driven with a servo fully embedded in each surface.


With the whole aircraft together once more, with the wings and tail in possition, the Valkyrie certainly looks like a mean machine. 


Bathing in the hot midday sunlight, the new 9ft long bomber sits ready to go. Showtime had arrived, again.  


The Test Flight 

It was that time again. Everyone was asking the question - what would happen this time? Would the aircraft get airborne? Here's the full video. 


Up high, the airplane really did look the business. Its iconic shape silhouetted against the bright sun is unmistakable. 


Unfortunately, the flight did not end well. The plane had revealed itself to have an unfortunate tendency roll back and forth on its lateral axis. Essentially, the plane oscillating tendency that was hard to control. Getting the plane too low and too slow due to a tailwind eventually caused a catastrophic tip stall. The 25lb Valkyrie bit the ground, hard. It was done. 



Aftermath

Once again, Ben and his team surveyed a wreck. This time, however, the plane had done its job. The mission was complete.


Huge congratulations from all of us here at Flite Test on a successful flight. The Valkyrie flew and carried out a flight in spectacular fashion. Memories were made and the experiences will certainly last a lot longer than any foam board airframe. 


Ben expertly crafted an airplane that combined complex engineering with aesthetical style and scale looks. This wasn't simply a case of scaling something up or strapping wings to an object that shouldn't fly, this was a true adventure into the world of full-on aeronautical design. Bring on the next project!


Links to other articles in this series 

Part 1

Part 2

Part 3


Article by James Whomsley

Editor of FliteTest.com

James@whomsley.net

www.youtube.com/projectairaviation

Instagram @jameswhomsley

COMMENTS

Nigel L on June 10, 2018
I think that rolling tendency was caused by the folding down wingtips. They were meant for stability at very high speeds (Mach 3 +) and I think at the slower airspeeds that models fly at it had the effect or an anhedral, which causes it to roll back and forth in my experience with it, which has been lengthy. Next time I might suggest some gyros that would auto-correct and also limit the flight envelope.
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gyroblackwell on June 15, 2018
I would add that the vertical stabs are small and not in the air stream when the nose is high.
this may or may not have contributed to the wing rocking.
Nice build by the way, and look forward to more new stuff from you.
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Bigjohn3592 on October 21, 2018
The high sweep of the wing causes a high dihedral effect. So any sideslip would cause the rolling we saw. The vertical fins are supposed to prevent unwanted sideslip. However, it is well known that when scaled down, scale size tail surfaces are less effective and are often oversized, even in scale competitions.
- Also, they fins would be less effective in high angle of attack, but that didn't happen.
- Also, the side area of the big long nose works against the fins to cause sideslip, because the nose has been changed from round to square in order to construct it from foamboard. ANd if there was any flex in the long skinny nose structure it could cause what we saw.
- Also, the rudders were hinged almost 90 deg from the way the full scale operated. And being so wide, they would have been hard for the small servos to handle. They may have been moving around quite a bit on their own.

One way or another, the rolling problems that caused the crash were built in, and not caused by tip stall..
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Ginormous XB-70 Valkyrie Project - Part 4 (Flight)