• This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn more.

BOB v4 Build for FF East 2019

#42
Huge pile of parts.

The tail and control surfaces are buried under there somewhere, counterbalances are glued onto the surfaces. All my cuts have been done on the hot wire, a blade hasn't touched a single part of this build.

Almost everything has been cut. Crazy stuff. Practicing my fiberglassing technique now before I start on the actual parts. P_20190617_165351.jpg
 

Chuppster

Well-known member
#43
I'm a little late to the party here, but I've been thinking about your props. If breaking propellers is a concern (it would be if I was in combat) I highly recommend using composite gas/glow props. You'll lose a bit of efficiency but those things are tough. I'm familiar with the propellers you bought and I think they are a good option (make sure you balance them before you mount them, I've had some come horribly out of balance) if you don't care about obstacles, but a gas/glow prop will probably hold up better in a collision.

On HobbyKing they have a brand called JXF Composite that's pretty good.
 
#44
I'm a little late to the party here, but I've been thinking about your props. If breaking propellers is a concern (it would be if I was in combat) I highly recommend using composite gas/glow props. You'll lose a bit of efficiency but those things are tough. I'm familiar with the propellers you bought and I think they are a good option (make sure you balance them before you mount them, I've had some come horribly out of balance) if you don't care about obstacles, but a gas/glow prop will probably hold up better in a collision.

On HobbyKing they have a brand called JXF Composite that's pretty good.
Unfortunately, they don’t make the JXF props bigger than 16 inches. I’ll look for other options though, needed to place an order anyways.
 
#46
It’s been a while since I’ve done an update. I epoxied the half rounds onto the horizontal and vertical stabilizers, still need to fiberglass the vertical stabilizer, horizontal stabilizer, and rudder.

One wing half is assembled (not in pictures), all the ribs are cut for spars, and the fuselage bits are cut out. All spares are also cut and glued.

Pictures can communicate the progress better.

12ED84EB-4623-41B2-8BE5-8CBD1DD595B9.jpeg E9AE5176-4FEE-4C40-B973-2A7F60B9BC70.jpeg 64DA13FD-30C2-4097-A197-D1033B81C6DC.png D9DFF5AD-EAC1-4D51-AD3B-49AFB453FDE3.png B241B117-2DC1-44AC-9A03-FCC5FF8071D3.png 53B6A273-7ECD-4263-AB27-48495F754DEB.png
 

b-29er

Active member
#47
Just out of curiosity, how are you planning on skinning the wings? does the lowes foam melt when you hit it with a hot glue gun?
 
#48
Just out of curiosity, how are you planning on skinning the wings? does the lowes foam melt when you hit it with a hot glue gun?
If you're using glue hot enough that it's bubbling/boiling coming out of the gun it'll melt the foam pretty bad, but hot glue is definitely usable in general.

I'll be skinning the wings in 3' sections, not sure what type of adhesive I'm going to be using yet.
 
#50
More photos. Working nonstop now.

Power system tested, all soldering done, working on the fuselage, paint on the tail is drying.
 

Attachments

#55
So. Some of you already know, or maybe you heard it hit the ground, but Bob is dead. Once I joined the wings I knew the 3/4" plywood spars weren't going to hold up. They broke right at a stress concentration from the wing mounts. Unfortunately, there wasn't a lot I could do at the event to fix it, so I gave it a test and the rest could have been predicted.

Takeoff was fine, wings started flexing, and down she went.

https://drive.google.com/file/d/1-59NCWkn9RXO-Dlv4UkP8LscsL0HG78o/view?usp=drivesdk

Screenshot_20190711-204207.png P_20190711_204419.jpg