Shop our Airplanes Products Drone Products Sales
Thread Tools
Dec 18, 2017, 12:27 PM
Registered User
Build Log

Prop in slot XB-70


A while ago I made a prop in slot XB-70 Valkyrie out of dollar tree foam board. I have looked around but wasn't able to find pictures or videos of other people doing this except for the Nico Hobbies XB-70, so unless someone proves me wrong, I am officially taking the title of "Creator of the first scratchbuilt prop in slot XB-70 documented on the internet". Unfortunately I crashed my first Valkyrie into a tree on the maiden, and it was destroyed. After putting RC on the back burner for a few months (due to a different crash) I saw this one post by softshell29 about his build of a massive balsa XB-70, and that really inspired me to bring my simple Valkyrie back.

A few days ago I got some more foam and started drawing the parts out. I started with the wings, and then drew out the parts for the undercarriage, canards, vertical stabs, and a few other parts that I could fit on the sheet. I am currently working on drawing the neck, fuselage, and nose on my third sheet. I should be able to finish today if I don't get caught up in other things.

Here's the link to softshell29's post: https://goo.gl/8mYRJa

I'll edit this post to include pictures when I get home.
Sign up now
to remove ads between posts
Dec 18, 2017, 06:11 PM
Kimbers Keeper.
BHOFM's Avatar
I, a friend and I have talked about doing one for some time, If you check the bottom of the page
there is a balsa prop slot XB-70 thread.

I have a high resolution three view I am going to use for plans. It will be a twin pusher though.

I did a SST early in the summer, it is a great flier. 2lbs, 600W. 2700kv motors.

I may use the same setup on the XB. Two 3s 1300 gives almost ten minutes flight time.



Don't have a pic when it was finished. Added windows and some other stuff.

I don't think I will do a thread on mine, I get little or no response. I end up locking the thread
when it gets to page 5.

Finished pic's.



Last edited by BHOFM; Dec 18, 2017 at 06:33 PM.
Dec 18, 2017, 07:30 PM
Kimbers Keeper.
BHOFM's Avatar
How are you going to stiffen the wing where the prop slot is? The lower fuselage sides need to run
full length. The best answer is a smaller prop and more KV.
Dec 18, 2017, 10:32 PM
Registered User
loonsmock's Avatar
Ooooh, I love the XB-70! I might just give this one a go, as my current scratchbuild project has not been going well and I could use a change of pace. Keen to see more! Also, do you recall what electronics setup your original one flew on?
Dec 19, 2017, 12:21 AM
Registered User
Quote:
Originally Posted by loonsmock
Ooooh, I love the XB-70! I might just give this one a go, as my current scratchbuild project has not been going well and I could use a change of pace. Keen to see more! Also, do you recall what electronics setup your original one flew on?
In short, the ft power pack c. More specifically, it ran a emax gt2215 1180 kv motor, 30 amp esc, and an 1800mah 3s battery, as well as two 9 gram servos and a 6ch rx.
Dec 19, 2017, 12:22 AM
Registered User
Quote:
Originally Posted by BHOFM
How are you going to stiffen the wing where the prop slot is? The lower fuselage sides need to run
full length. The best answer is a smaller prop and more KV.
On the original I had some om BBQ skewers implanted in the wing perpendicular to the slot that acted as spars. Maybe not the best but better than nothing.
Dec 19, 2017, 12:26 AM
Registered User
Here's what I was able to cut out tonight. The nose/fuselage, the neck, and one of the supports for the undercarriage. Tomorrow I'll tackle the undercarriage, some of the stabs, and i might have some got glue by then so I might start gluing the parts together.
Dec 19, 2017, 08:05 AM
Registered User
Captain Dunsel's Avatar
I think you're talking about my prop-in-a-slot XB-70. Yes, it was all wood, which is why it was heavier -- too heavy to fly well. If I ever get around to it, I'll do another one, but made from foam and not wood.

Oske, I don't know if this will help you, but let me tell you what happened with the two XB-70's I built.

The big problem I ran into was a LARGE shift in the CG when going a prop-in-a-slot to a full winged pusher. The CG moved forward several inches, so the pusher was terribly tail-heavy at the same CG location. I moved the battery to just behind the canards and (sacrilege, I know) added long extensions between the ESC and the motor AND between the ESC and the battery. It still was a handful and barely survived it's only flight (which ended in light damage from a stall/spin from about 10 feet). After the one flight, I decided not to pursue the project.

Break a leg, Oske!

CD
Dec 20, 2017, 08:10 PM
Kimbers Keeper.
BHOFM's Avatar
Mine is almost done, waiting on the motor, esc, prop. Fri, Sat, maybe.
Dec 20, 2017, 10:45 PM
Going back to balsa
Quote:
Originally Posted by BHOFM
Mine is almost done...
Incredible! You are an interesting guy BH.

PS - I hope that it will fly great.
Dec 20, 2017, 10:59 PM
Registered User
Got all the parts cut out, got some glue, and I've got 2 weeks off to work on this project.
Dec 21, 2017, 02:32 AM
Registered User
Been a productive night. Got most of the parts glued together. Still need to glue the fuse to the wings, attach elevons and stabs, get the electronics worked out, and a few other things. For now, that's enough for tonight. I'll probably be able to finish it within the next few days and might make a video on it.
Dec 21, 2017, 09:25 AM
Kimbers Keeper.
BHOFM's Avatar
Looks bigger than mine? Span? Mine is 32"X60". Just a bit longer than the SST.

Looks good, like the wind screen.
Dec 21, 2017, 03:08 PM
Registered User
Quote:
Originally Posted by BHOFM
Looks bigger than mine? Span? Mine is 32"X60". Just a bit longer than the SST.

Looks good, like the wind screen.
surprisingly, the span on mine is 35x30", but about 35x50" if you include the length of the fuselage. Also thanks, i tried to make the new nose more realistic, the old one looked like something out of a cartoon.


Quick Reply
Message:

Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Build Log B-70 Project.......RC XB-70 softshell29 Giant Electric Planes 587 Sep 21, 2018 05:29 PM
Build Log XB-70 Prop in a Slot Captain Dunsel Pusher Prop Jet Models 57 Nov 16, 2016 02:48 PM
Discussion Videos: Hollywood Goes to War,XB-70,WW2 Test Pilots,JG 26,75mm B-25s & more zeno General Aviation 0 Nov 11, 2015 11:05 AM
Discussion Videos: Hollywood Goes to War,XB-70,WW2 Test Pilots,JG 26,75mm B-25s & more zeno General Aviation 0 Nov 11, 2015 11:00 AM
Discussion XB-70 xb 70 Valkyrie Ted61 Giant Electric Planes 1 Jul 23, 2008 01:48 PM