XB-70 Valkyrie: FT Style

[Mid7night]

Curious what sort of spar situation you are looking at. As your folds are showing that span-wise you are using the weak length of the foam grain. Not doubting your mad ski11z, just offering a consideration.

Since I'm expecting relatively light total wing loading, thanks to the massive total area, I'm not planning on a lot of reinforcement. Also, think about how the wing is attached and supported; it sits on top of the inlet/fuse/body volume. So there's really only maybe half of the 'mid' wing that is unsupported outboard of the side-of-body joint, and the body itself will act like an under-wing-box. I will probably put in at least one main spar that will span the center-wing-join, and go out to where the main gear attach, because that will be a pretty strong point-load.

For the wingtips, I'm still sorting out exactly how I'm going to actuate and support them properly, but yes; there will be some additional "something" in the wingtips for the folding loads.

 

[Mid7night]

More progress! I laid out the right-hand inboard wing just to see it, and realized I need to think through the seam joints a bit more. The spars are there to keep the overall wing shape, but because of the sheer size of the sheets I think I need some form of rib or at least a skin doubler to keep it from sagging between. We'll see what I come up with. Trying to keep it light, too.




So I tackled the nose and neck instead, since those pieces are also rather delicate in their un-built form, I figured they will survive longer if I just glue them up.

This is the forward section that I will need to make removable for transport. It's pretty cavernous, but there's actually not a lot that will go inside except the canard and its servos. Maybe some sensors, but that's it. The batteries will all go just aft of the neck, over the wing/body centerline.

 

[foamtest]

Holy crap! I just realized how large this model is actually going to be. Also are you taking this to FFE in 2018? I would love to see this in person.

 

[Mid7night]

Holy crap! I just realized how large this model is actually going to be. Also are you taking this to FFE in 2018? I would love to see this in person.

I know how you feel! With every part I lay out and start to work on, even I am taken aback by the scale!

FFE'18: I cannot say "it will be there" with any level of certainty. I WILL truck it to FFWest'18, wherever that ends up being, so rest assured that you will see it in some fashion.

But let me just say, about FFE'18; "I WANT to"...

 

[rockyboy]

I know how you feel! With every part I lay out and start to work on, even I am taken aback by the scale!

FFE'18: I cannot say "it will be there" with any level of certainty. I WILL truck it to FFWest'18, wherever that ends up being, so rest assured that you will see it in some fashion.

But let me just say, about FFE'18; "I WANT to"...

Maybe you can convince Boeing to save a spot for it in a shipping container of stuff for the booth... Boeing was heavily involved in the design after all

 

[Mid7night]

Maybe you can convince Boeing to save a spot for it in a shipping container of stuff for the booth... Boeing was heavily involved in the design after all

Actually it was North American. Boeing was the competitor who lost ...and then years later bought Rockwell, who had previously acquired North American... so technically now the Valkyrie IS part of "Boeing", but it is "heritage North American Aviation". :-S

But to your ACTUAL point...yeah, I'll just agree with you; getting Boeing's help would be a good idea.

 

[rockyboy]

Actually it was North American. Boeing was the competitor who lost ...and then years later bought Rockwell, who had previously acquired North American... so technically now the Valkyrie IS part of "Boeing", but it is "heritage North American Aviation". :-S

I miss-understood the nature of the NA vs Boeing contracting on this

Guess my professor was right - relying on Wikipedia too much did get me in trouble one day

 

[Mid7night]

I miss-understood the nature of the NA vs Boeing contracting on this

Guess my professor was right - relying on Wikipedia too much did get me in trouble one day

Sorry, you're not totally wrong. I just re-read my Valkyrie book; Boeing WAS the losing competitor in the original bomber competition, but then after NAA won they started sub-contracting out all the parts, and Boeing was prime on the wing. Kinda funny how that circle went.

 

[DamoRC]

As always, Ben inspires. This is gonna be huge (size and sound). Need to start thinking of a big build for FFW.

DamoRC

 

[rockyboy]

Sorry, you're not totally wrong. I just re-read my Valkyrie book; Boeing WAS the losing competitor in the original bomber competition, but then after NAA won they started sub-contracting out all the parts, and Boeing was prime on the wing. Kinda funny how that circle went.

A little like the old Wacky Races cartoon

 

[F106DeltaDart]

Speaking of the history, I thought I'd share this here (I can move it to a different section if it doesn't fit well). One of my favorite docs on this awesome bird:

For the control surfaces, are you planning on all of the small surfaces like the full scale, or simplifying to conventional elevons? Will the whole upper part of the vertical stab pivot, or will it use a normal rudder? This is such a cool project, and I can't wait to see it take shape. Its already massive, and you've hardly started .

 

[Mid7night]

I love that video! I referenced it a LOT when learning about the landing gear especially.

I'm not planning on having ALL the elevon breaks the full-scale had. I will have four total elevons: 1 on each inboard wing, inboard of the fold, and one on each folding wingtip outboard of the break. I'll have lines on them to visually represent the multi-element breaks, but it would be too heavy to actually have that many servos and rods. At this scale, it's still 'small enough' that I can gang them up a bit.

For the rudder, I think I WILL replicate the full-scale hinge-line. I don't anticipate them having much deflection, so I think I can make it robust by using mechanical advantage; SHORT servo-arm, and longer surface-arm.

 

[AkimboGlueGuns]

That's a great documentary. It's a shame there isn't more footage of this airplane. It's a very interesting subject.

 

[NicTheEngineer]

I considered that for a few minutes...but...

The duct...no problem. The fan? Scary idea IMHO. I doubt a 3d printed one would hold up. Better to use a 3d printed mold to cast one I'd think. And the big expense is the motor which isn't going to be printed anyway.

I have zero experience with EDF's so far (just got my first one to go in my X-29 but still need an ESC before I can get that going) but my gut is telling me not a great idea to try and 3D print one. Still...interested in seeing what YOU do

Fired up the MPCNC with needle cutter and cranked out an FT-70_chucker for my daughter tonight:

View attachment 95889

Took about 10 minutes to cut, probably less time than I'd spend printing and taping plans to cut by hand (Yeah, I did spend about 5 minutes on the CAM...but if I make more than one of these it's amortized over all of them. And if it flies as well as Ben's did I can easily see making a dozen or so to bring on one of our camping trips this summer for the various kids in camp to play with.)

If you look close you can probably see the one little T-pin current holding it together. Tomorrow she gets to fire up her glue gun and do the "real" assembly

I have tried to print out 70mm edf and i only used 3s and it was scary every moment of it... the first run up of it was terrifying but on The Hacksmith youtube channel they have tried 3d printing 120mm edfs and have had minor success with them. so a smaller one if done right could work. Also due to the minor inconsistencies of 3d printing balancing the impeller would be a pain in the rear

 

[AkimboGlueGuns]

I have tried to print out 70mm edf and i only used 3s and it was scary every moment of it... the first run up of it was terrifying but on The Hacksmith youtube channel they have tried 3d printing 120mm edfs and have had minor success with them. so a smaller one if done right could work. Also due to the minor inconsistencies of 3d printing balancing the impeller would be a pain in the rear

Psssh. You don't need to balance an EDF! It sounds way cooler when the whole assembly vibrates. It's an added touch of realism.

 

[F106DeltaDart]

I love that video! I referenced it a LOT when learning about the landing gear especially.

I'm not planning on having ALL the elevon breaks the full-scale had. I will have four total elevons: 1 on each inboard wing, inboard of the fold, and one on each folding wingtip outboard of the break. I'll have lines on them to visually represent the multi-element breaks, but it would be too heavy to actually have that many servos and rods. At this scale, it's still 'small enough' that I can gang them up a bit.

For the rudder, I think I WILL replicate the full-scale hinge-line. I don't anticipate them having much deflection, so I think I can make it robust by using mechanical advantage; SHORT servo-arm, and longer surface-arm.

Very cool! I wonder if some linear servos might work for those folding tips. I know firgelli makes some smaller ones that are good but pricey. Maybe the actuators from the Banana Hobby folding-wing corsair could be made to work.

 

[Mid7night]

Very cool! I wonder if some linear servos might work for those folding tips. I know firgelli makes some smaller ones that are good but pricey. Maybe the actuators from the Banana Hobby folding-wing corsair could be made to work.

Possibly, but those Firgelli aren't cheap. The folding tips are actually an area I had (somewhat) mapped out from the start: I have two MASSIVELY torquey servos (standard case size, 212 oz-in) that used to be in one of my PSS slope gliders. I plan on having them operate on a slowed-channel, and hook up the shortest servo arm possible with the longest hinge-horn that fits in the wing.

The hinge itself will be piano-hinge style, with an aluminum tube sleeve and a carbon tube as the rod. That way, also, I can remove the folding tips by simply sliding out the carbon tube and disconnecting the fold pushrod.

 

[LitterBug]

I have tried to print out 70mm edf and i only used 3s and it was scary every moment of it... the first run up of it was terrifying but on The Hacksmith youtube channel they have tried 3d printing 120mm edfs and have had minor success with them. so a smaller one if done right could work. Also due to the minor inconsistencies of 3d printing balancing the impeller would be a pain in the rear

I only need 50mm for my particular project. Starting with 5 blade props, and will work on a EDF prop later.


Have some 10,000kv motors to play with... should be fun to play from a safe distance.

Cheers!
LitterBug

 

[Mid7night]

So, I've been experimenting with Youtube Live streams, and I did a couple unboxing's as I start receiving parts the past couple of days. I plan on doing some more detailed talk-thru videos in the future, but for now, here's where we're at!

Landing gear parts!

d

 

[Mid7night]

UPDATE: Check post #1, I've updated the FT-70 chuck-glider plans!