PsyBorg
Wake up! Time to fly!
One of my tasks for Team Rockboy's FW-42 build is to design scale bombs (the SC250) for the bomb drop portion of the contest. I have completed a basic design from a few ideas I have thought over and adapted as I was working thru it all. I wanted to not only have scale bombs to drop but I wanted them to go "POOF" and actually mark the spot they hit.
My original idea was to make a hollow scale body and fin assembly and to use a plunger style actuator. On the first attempt I had worked out a really simple and decent looking scale bomb for a 1/10th scale 500lb bomb of the era. I found that the plunger idea would not function smooth enough as well as add length to the bomb bay to house them with a few inches of plunger sticking out the nose.
After thinking it over a bit I had mulled the ideas of "Packet charges" like the marking powder wrapped in plastic wrap used in the kitchen. Then realized that would STILL require a plunger to break it open and not have any air pressure to force it to spread in the "Poof" pattern I want.
I talked with Igoo57 this afternoon about ideas and he came up with using a single ply napkin and wrapping the power in that and just taping it to the nose so it broke on impact. That was doable for marking the impact but still no "Poof". this lead us around again to a pressurized system. We had a few ideas and decided I would try small balloons verses the original condom / finger cot ideas that would be expensive.
With the shape of the balloon in my mind one of those sucky ball things they use to wash ears out and clean baby's ears with as the "warhead" popped up. This may still be a viable option at some point but they tend to be thicker rubber and harder to impact and produce a good puff of air. Anyway back to the balloon idea and off to the dollar store I went. When I got there and was looking around I saw the big rubber kick balls for kids that are really flexible and soft. That got me thinking to use a smaller one and cut them in half.
Well a while later after looking all over AND asking the clerk for help we got no where as the only small ones they had were solid. Well I finally gave up on that and started looking for a method to magnify the FPV view from a camera to use as a bomb sight for targeting more accurately. No dice in that train of thought either. It was then I passed the pet isle and saw the squeaky toys. Round, soft, pliable, and VERY annoying. I though what a great demise for such things. I managed to find two of them close to the size I needed.
Home I went with my balls in a sack and a drink in hand to further move the project forward. (had to do a check to see who is still reading all this AND paying attention)
I started cutting the pointy tips off the outer surface so it looked more like a Warhead and not a mine. I then cut the ball in half to be glued to my body / fin assembly. I left a few points on for durability but later found they kept it too stiff to produce the puff of air I wanted.
Here are the pieces parts and final assembly after a successful proof of concept and a material failure.
Squeaky toy that will become the war head.
New fin and body assembly
Payload delivery system MK1
Delivery vent
Body assembly and warhead (actuator)
Tested and successful Billy Bomb V1
Thru flight testing... (AKA tossing around the parking lot out side) I went thru many attempts. The first ones were too weak as I did not fill the warhead with enough flour to make it go poof. Several refilling to find a happy amount were needed as well as altitude testing (AKA tossing it higher) to get the desired results. I found the bomb actually tracks and falls straight with only a 10 - 20 foot fall to right itself and hit on the warhead every time. I also found if I put a spin on it the trajectory tightened up even more. Sadly the scale original design does not warrant any rotation so it has straight fins. The only thing left to add is BBQ skewer to the fins to make scale supports used on the originals.
I found the happy place I wanted the bomb to be in surprisingly quick. The only think I would probably change is to use colored chalk powder instead of flour for a more trackable method for knowing who hit where. That and the mounting of the warhead will have to be explored as the hot glue does not stick to the rubber very well. I will more then likely after a few refinements use RTV for final assembly as I know that bonds well to both foam board and rubber.
Once I work out a few minor kinks I will quick learn auto cad and produce a workable plan so other may build and or modify to suit their needs.
My original idea was to make a hollow scale body and fin assembly and to use a plunger style actuator. On the first attempt I had worked out a really simple and decent looking scale bomb for a 1/10th scale 500lb bomb of the era. I found that the plunger idea would not function smooth enough as well as add length to the bomb bay to house them with a few inches of plunger sticking out the nose.
After thinking it over a bit I had mulled the ideas of "Packet charges" like the marking powder wrapped in plastic wrap used in the kitchen. Then realized that would STILL require a plunger to break it open and not have any air pressure to force it to spread in the "Poof" pattern I want.
I talked with Igoo57 this afternoon about ideas and he came up with using a single ply napkin and wrapping the power in that and just taping it to the nose so it broke on impact. That was doable for marking the impact but still no "Poof". this lead us around again to a pressurized system. We had a few ideas and decided I would try small balloons verses the original condom / finger cot ideas that would be expensive.
With the shape of the balloon in my mind one of those sucky ball things they use to wash ears out and clean baby's ears with as the "warhead" popped up. This may still be a viable option at some point but they tend to be thicker rubber and harder to impact and produce a good puff of air. Anyway back to the balloon idea and off to the dollar store I went. When I got there and was looking around I saw the big rubber kick balls for kids that are really flexible and soft. That got me thinking to use a smaller one and cut them in half.
Well a while later after looking all over AND asking the clerk for help we got no where as the only small ones they had were solid. Well I finally gave up on that and started looking for a method to magnify the FPV view from a camera to use as a bomb sight for targeting more accurately. No dice in that train of thought either. It was then I passed the pet isle and saw the squeaky toys. Round, soft, pliable, and VERY annoying. I though what a great demise for such things. I managed to find two of them close to the size I needed.
Home I went with my balls in a sack and a drink in hand to further move the project forward. (had to do a check to see who is still reading all this AND paying attention)
I started cutting the pointy tips off the outer surface so it looked more like a Warhead and not a mine. I then cut the ball in half to be glued to my body / fin assembly. I left a few points on for durability but later found they kept it too stiff to produce the puff of air I wanted.
Here are the pieces parts and final assembly after a successful proof of concept and a material failure.
Squeaky toy that will become the war head.
New fin and body assembly
Payload delivery system MK1
Delivery vent
Body assembly and warhead (actuator)
Tested and successful Billy Bomb V1
Thru flight testing... (AKA tossing around the parking lot out side) I went thru many attempts. The first ones were too weak as I did not fill the warhead with enough flour to make it go poof. Several refilling to find a happy amount were needed as well as altitude testing (AKA tossing it higher) to get the desired results. I found the bomb actually tracks and falls straight with only a 10 - 20 foot fall to right itself and hit on the warhead every time. I also found if I put a spin on it the trajectory tightened up even more. Sadly the scale original design does not warrant any rotation so it has straight fins. The only thing left to add is BBQ skewer to the fins to make scale supports used on the originals.
I found the happy place I wanted the bomb to be in surprisingly quick. The only think I would probably change is to use colored chalk powder instead of flour for a more trackable method for knowing who hit where. That and the mounting of the warhead will have to be explored as the hot glue does not stick to the rubber very well. I will more then likely after a few refinements use RTV for final assembly as I know that bonds well to both foam board and rubber.
Once I work out a few minor kinks I will quick learn auto cad and produce a workable plan so other may build and or modify to suit their needs.
