FTCC18 "Billy Bomb" proof of concept
- Thread starter PsyBorg
- Start date
PsyBorg
Wake up! Time to fly!
Nice work Joshua. That is a nice system (for the scale Americkonz)
I was hoping someone would have popped in by now with some soft 3d printed nose cones to try on the Billy bomb. Since non have come forward I will progress with Version two.
Just a suggestion (since I worked with REAL bombs and dropping mechanisms in the Navy) test that drop mechanism for lateral movement as them bombs are gonna be a rockin and a rolling in flight and may pop loose on their own or stress the tiny tabs. Maybe run some angled side supports off the mount to keep them stable in flight so that won't happen. Specially if they are to be wing mounted. Its not so important in a bomb bay like I am working with.
I was hoping someone would have popped in by now with some soft 3d printed nose cones to try on the Billy bomb. Since non have come forward I will progress with Version two.
Just a suggestion (since I worked with REAL bombs and dropping mechanisms in the Navy) test that drop mechanism for lateral movement as them bombs are gonna be a rockin and a rolling in flight and may pop loose on their own or stress the tiny tabs. Maybe run some angled side supports off the mount to keep them stable in flight so that won't happen. Specially if they are to be wing mounted. Its not so important in a bomb bay like I am working with.
I've not posted a file yet for the drop mechanism. I'd like to finalize my bomb version.
For those interested... I've started off with the mechanism as small as possible. If you feel like you need a bigger mechanism you can scale it up and adjust your infill. The same goes with the bomb. Printed at its current size... it weighs next to nothing. I'm not too worried about side loads but I want to do in-flight testing before I release either the bomb or drop mechanism. The two-pronged clip also helps to eliminate some of those side loads.
I'm working on having the bomb in 3 pieces now. The fins, main bomb body, and the nose. The nose will be a slip-on cap that you can either glue on or leave loose to replace if you enlarge it or fill it with a powder. Of course, separating the nose from the body to release the powder is another issue altogether. Still thinking on a mechanism to do that, if it can be done.
I've modeled the bomb body and nose as a single print and had it print successfully with 0 infill. It is plenty strong but I think most users will not want to wait for the print at 0.1mm layer height to achieve that. With 10% infill it should go much better but it has yet to be tested.
I'm moving closer on this. I got my Carl Goldberg Eagle II up and flying this past weekend and it is a prime candidate to try this out on.
For those interested... I've started off with the mechanism as small as possible. If you feel like you need a bigger mechanism you can scale it up and adjust your infill. The same goes with the bomb. Printed at its current size... it weighs next to nothing. I'm not too worried about side loads but I want to do in-flight testing before I release either the bomb or drop mechanism. The two-pronged clip also helps to eliminate some of those side loads.
I'm working on having the bomb in 3 pieces now. The fins, main bomb body, and the nose. The nose will be a slip-on cap that you can either glue on or leave loose to replace if you enlarge it or fill it with a powder. Of course, separating the nose from the body to release the powder is another issue altogether. Still thinking on a mechanism to do that, if it can be done.
I've modeled the bomb body and nose as a single print and had it print successfully with 0 infill. It is plenty strong but I think most users will not want to wait for the print at 0.1mm layer height to achieve that. With 10% infill it should go much better but it has yet to be tested.
I'm moving closer on this. I got my Carl Goldberg Eagle II up and flying this past weekend and it is a prime candidate to try this out on.
Looking forward to the model to try a print of it. Also have a spool of flexible filament on order to see if we can get some decent looking squishy nose cones. Assuming I can get the printer to crank out something decent looking with this filament, should be able to crank out a couple handfuls nose cones in short order 
Anyone have ideas on a Bay stack, short of a door at the bottom of a cartridge of bombs?
I'm thinking like a Vr control where they release one at a time as the knob turns. Allowing for multiple passes or a large load drop with a quick turn of the knob. All I see are the left-right two bomb drops at best.
Here was my idea for collapsible bombs. Wouldn't work well in a medium grassed field but short grass and pavement might.
I'm thinking like a Vr control where they release one at a time as the knob turns. Allowing for multiple passes or a large load drop with a quick turn of the knob. All I see are the left-right two bomb drops at best.
Here was my idea for collapsible bombs. Wouldn't work well in a medium grassed field but short grass and pavement might.
Fluburtur
Cardboard Boy
I was just thinking about that kind of thing, the nose that slides into the bomb but you need enough inertial to get the powder out. As for sequencial release of bomb, a very old idea I had was a long pull pin with shorter pull pins of variable size linked to it so depending on the speed you pull the whole thing the bombs release.
Or you could make a barillet of the 3d printer bomb release system, that would work well for a bomber with an internal bay.
Or you could make a barillet of the 3d printer bomb release system, that would work well for a bomber with an internal bay.
PsyBorg
Wake up! Time to fly!
Foamy.
I originally tried the two piece compression design like the direction you are heading. The problem lies with the weight added to the back half of the bomb to get it to compress properly makes it tumble. I am sure with the fins at higher altitude they could get it to track properly but I seriously doubt you will be dropping high enough to be consistent let alone not have winds push these tiny things around.
That is why I lean towards the "bubble" nose where there is weight for the bomb to track straighter and the compression is soft and all in one direction not split in two halves.
I figure we would not be dropping much higher then what we can hand launch them as we are going for accuracy of the hit.
I originally tried the two piece compression design like the direction you are heading. The problem lies with the weight added to the back half of the bomb to get it to compress properly makes it tumble. I am sure with the fins at higher altitude they could get it to track properly but I seriously doubt you will be dropping high enough to be consistent let alone not have winds push these tiny things around.
That is why I lean towards the "bubble" nose where there is weight for the bomb to track straighter and the compression is soft and all in one direction not split in two halves.
I figure we would not be dropping much higher then what we can hand launch them as we are going for accuracy of the hit.
I tried my latest version of the bomb and I think I'm done. The nose does not come off so there is little hope for a powder release. The thing is STRONG!
I want to note that the interior of the nose is conical so it should take quite the beating but you can friction fit it only so that in the event that you hit a bunch of rocks or really manage to mangle it... simply print a new nose and your are off again. There is also a bit of a hollow area that you can add some ballast to the nose for a more direct (less scale) trajectory. The advantage is that the added mass will also help with wind penetration. You can simply add some hot glue to a fishing weight and pop it inside the cavity of the nose. As it prints, it is balanced well. More details to come on getting this.
I want to note that the interior of the nose is conical so it should take quite the beating but you can friction fit it only so that in the event that you hit a bunch of rocks or really manage to mangle it... simply print a new nose and your are off again. There is also a bit of a hollow area that you can add some ballast to the nose for a more direct (less scale) trajectory. The advantage is that the added mass will also help with wind penetration. You can simply add some hot glue to a fishing weight and pop it inside the cavity of the nose. As it prints, it is balanced well. More details to come on getting this.
All set to test out for the weekend... getting this ready to share the files as well...
https://www.facebook.com/joshua.d.orchard/videos/10103270831684131/
https://www.facebook.com/joshua.d.orchard/videos/10103270831684131/
Well, I would say it was a successful day.
Build video for the bomb is below and the build for the release mechanism is coming.
Files can be found at:
http://joshuaorchard.etsy.com
Build video for the bomb is below and the build for the release mechanism is coming.
Files can be found at:
http://joshuaorchard.etsy.com
It was a total blast! I would have 5 or so flights on each pack just going up, dropping the bomb and coming down. It works so very well and I can see many many other things dropped from aircraft using this simple mechanism.
So I've been trying to 3D print a flexible nose for the Billy Bomb and my printer extruder is driving me nuts. It makes it about 3 to 5 minutes into the print job and then just spews the filament out through a gap in the side of the extruder instead of down into the hot end. And from looking around, this seems to be a fairly common challenge with printing flexible filaments, with the solution often being "get a new extruder".
What I'm not finding a lot of information on is "what extruders DO work well with flexible filaments and a Prusa i3 style machine". The Flexion has come up a couple times, but honestly it's usually the Flexion rep chiming in to say "hey, our product works great!"
Does anyone lurking on this thread have any experience with this before I figure out how to get one of these into my hobby budget?
What I'm not finding a lot of information on is "what extruders DO work well with flexible filaments and a Prusa i3 style machine". The Flexion has come up a couple times, but honestly it's usually the Flexion rep chiming in to say "hey, our product works great!"
Does anyone lurking on this thread have any experience with this before I figure out how to get one of these into my hobby budget?
PsyBorg
Wake up! Time to fly!
Maybe the place to ask is in the cutting foam with a needle thread. They are all 3d guys and I am sure they do printing as well as cutting and may have good advise? Jhitesma would also be another good person to poke with a stick for help too I would think. I know ZILCH about all that new fangled stuffs.
LocalFiend (Dale Stratton) has done flex filament a bit. You may want to look him up and ask.
A prusa i3 based machine should be able to print flexibles so long as you know the right tricks.
Number one in your case would be adjusting the filament clamp tension on your extruder. For soft flexibles you want to make sure that the screw tension is just enough to grab the filament. Too much more than that and stuff will squirt out the side. The higher the shore hardness of the filament, there more clamping pressure can be tolerated.
Secondly, slow down your print speed. Start at something like 20mm per second. Once you get successful prints you can boost that number.
Third, make your first layer height higher. You need to give flexibles more space to lay down on the bed at the begging. Squishing it into the bed creates backpressure which can jam up the extruder, or make filament pop out the side.
Fourth, set the temp at the high end of the range to start out. More temp means it will flow easier.
And lastly, disable retraction. You may be able to turn i t on after more tuning, but start out with it off. To counter stringing, find the option in your slicer that tells it to avoid crossing outer perimeters
Thanks Dale! I went in the complete wrong direction on the clamp tension - that probably hasn't helped me at all :black_eyed: I was starting at 25mm/s but will slow down some more, and tweak in the direction of your other recommendations too.
Also, anyone else think it's a little spooky how if we mention localfiend's name he immediately pops up in the thread?
Should we try this in other threads to see if works there too?
LOL, I messaged him through FB with a link to the thread. I gotcha covered!
I gotcha covered!Similar threads
