XB-70B Valkyrie B

[Brian B]

Brian B submitted a new resource:

XB-70B Valkyrie - XB-70B Valkyrie Dual pusher 67in x 42in -plans and manual

Super satisfied how my prototype worked out, and I think this new revised design will be even better. For now I'm working on other projects, but I'll come back and build Rev 2 myself sometime. Turns heads at the field, especially in this fictional livery.

Notice the detailed build manual.

Read more about this resource...

 

[JakeTheSloth]

I'm just here to say that if anyone says that pusher props on jets instead of EDFs are faux pas must've never heard 2 high speed props buzzing on one, it sounds and looks fantastic. Great job! The wheel in belly preventing it from scratching on landings is ingenious

 

[Brian B]

I'm just here to say that if anyone says that pusher props on jets instead of EDFs are faux pas must've never heard 2 high speed props buzzing on one, it sounds and looks fantastic. Great job! The wheel in belly preventing it from scratching on landings is ingenious

Single drivetrain on this one sounded really good too, with that tight fitted (kort) nozzle amplifying the sound even more. Similar drivetrain to the B-70, but a higher KV with less prop pitch. Looking forward to someone else tackling that B-70. Glad you enjoyed the vid.

 

[LitterBug]

I visit the XB-70 in Dayton regularly.... May add it to my list for next winter. Have my hands full this buildruary. I have some 8 blade props that might sound really cool on it...

 

[don44039]

Does anyone know what motors are recommended
thanks don

 

[LitterBug]

From the manual on the downloads page, looks like typical quad motors:

Simple effective motor mount made from plywood and epoxied into place (bonded to foam, not the
paper). With two 40amp ESCs, I’m using 2306 - 1750kv motors with a heavier pitch 51499 prop.

But this other 2306-2250kv with a 51477 prop is another good combo, solid 5 min flights.

 

[don44039]

ok finally got aroud to cutting the parts.
On the main wing panels, there is a long dashed black line, which is not in the description. Is it a cut? only the top paper? not sure what to do with it.
thanks don

 

[LitterBug]

Looks like that is where the rear of the wing fold should be

 

[don44039]

So, should it be cut just the top paper to enable a fold like the dashed blue line?
thanks
don

 

[LitterBug]

I think it is just a line for alignment, but having never built it, I am not certain. @Houndpup Rc ??

 

[Brian B]

Sorry about that incompleteness. It was a line showing where to scribe a cut thru the paper only, to peel off a large swathe of paper ahead of it. Reason was to hot glue to the foam and not the paper, since over time the paper could delaminate. Look in section BB, and note where is says "No Paper / Paper". It falls a little short of where the top folds down, so don't try using it for that purpose.

 

[Brian B]

You could consider preforating the paper with a toothpick along the edge instead, to allow the glue to get to the foam, if you are not using hot glue. You might practice-fold over first, sketch a line, then cut slightly behind it, to make sure the paper is intact until under the cap.

 

[Brian B]

Oops. To be consistent with the section BB, this spar should be pre-glued on THIS side of the fold crease. It would work ok on either, but this is the No-Paper side of the panel.

 

[don44039]

ok that helps alot
thanks
doc

 

[don44039]

This piece is not on any of the pdfs
don

 

[Brian B]

Follow this link to PDF download. I thought I'd updated here previously.

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[don44039]

Here is where I am stuck see pics
I get that folding the wing. What is not clear to me is where the spars go. I numbered them, so if you could draw lines on xb73 as to where to place them, and also where to remove the paper. I get that it is hard to explain it when it makes perfect sense in your mind to someone else.
thanks
don

 

[Brian B]

Sorry, hope my delay isn't holding you up.

In the manual's wing cross section view, you can see the Mid and Front spars planely (attached below). They are glued first to the underside of that top panel (paper removed from wing). They are different lengths, and the wing pattern shows placement with gray dashed line rectangles. (See my 2nd Wednesday post for minor correction on placement, but it works ok either way).

The third spar is shortest, and it's optional, only used if you make it with the cardboard cap. In the section view in the manual it is not visible, but it IS visible in the exploded 3D image from Wednesday.

 

[Brian B]

 

[Brian B]

The section views A-A and B-B shows the demarcation lines for removing paper. The bottom view in each section AA and BB is before bending. See the wing panel with the phantom lines with the A and the A arrows, and B &B, and you can see how the section view details match up.