Bomb Drop Questions

[BayDesigns]

Hi again! I'm looking to build a bomb drop for the Eclipson EGW-80. Since it's a flying wing, I have some questions. First, since it can't be a centerline pylon (I'd rather not suck a PLA projectile through my prop, thanks.) I'm wondering if I can safely mount the release on only one wing (for testing, another "bomb" or a special pod will occupy the other wing after I validate this experiment) and still fly decently. Does anyone have advice? I'm planning on 3D printing the hardpoint/shackle/release pin set. I'll use this system not only to drop stuff, but if I want to mount an additional FPV camera, probably to get a view of the fuselage/wing for flight testing. Thanks!

 

[JasonK]

the only problem I see with off center 'bombs' like that on a flying wing is the lack of differential thrust/rudder to deal with the off center drag.

I was doing ribbon combat with a FT dart and the other person's ribbon got stuck on my servo horn, to counter act the drag, I had to hold hard against it to run enough differential thrust to make up for the drag.

if you have paired drops and drop them at the same time, you would probably be ok unless something bad happened and only 1 dropped.

 

[Hai-Lee]

Just as a thought you could use the same bomb release mechanism as used on the Stuka divebombers to clear the propeller arc on release.

With a little clever work it could be managed and retracted by a single servo.

Just a thought!

Have fun!

 

[BayDesigns]

Interesting! Thanks for the input.

 

[Fluburtur]

A servo releasing a mouse trap would more or less do that, recoil might even kick up the plane a bit hehe.

 

[L Edge]

Suggest you drop bomb from center where release is inside fuse and bomb is outside. If bomb is not lightweight, gravity will prevent hitting the prop, unless climbing. Near CG line is best.

If release system is on one wing and bomb on other (external) as you described, your frontal drag and difference of weight when released could cause yaw, roll and perhaps pitch. With no rudder to control yaw, the flight will be short.

 

[BayDesigns]

Seems like either a dual-drop or a centerline sling is in order! I’ll probably CAD up a Stuka-type sling first and then if the tests are successful, I can try a dual drop. Of course, I might just wait until I get a 4-channel to do wing pylons.

 

[BayDesigns]

I hate to dig this up again, but I’m curious- do you think that a pylon with springs integrated into it would work? when the release pin is pulled, the bomb is not only released by gravity, but it gets actually forced off the aircraft. Obviously this depends on the spring, but do you think a fairly small/light spring could give me enough push to get the object clear of the aircraft?

 

[JasonK]

could work -> yes

another thought I just had... you could cut your throttle, drop, then start it back up, then your prop wouldn't be spinning with any force even if it bumped.

 

[BayDesigns]

That’s probably the best plan- saves weight, and there’s no chance of failure. Once I get this thing built, I’ll definitely have some experimenting to do.

 

[Ketchup]

If you just cut the throttle you could even consider an esc brake to make sure that the prop isn’t spinning when the bomb is dropped.

 

[Hondo76251]

I don't think it would hit the prop if it was near CG to begin with. The bomb is going the same speed as the plane, it wont immediately slow down when released. Might be worth a try in the middle just for simplicity sake.

 

[BayDesigns]

I don't think it would hit the prop if it was near CG to begin with. The bomb is going the same speed as the plane, it wont immediately slow down when released. Might be worth a try in the middle just for simplicity sake.

Probably a good idea, props aren’t ridiculously expensive.

 

[Ketchup]

Probably a good idea, props aren’t ridiculously expensive.

Even if it does hit the prop I don’t think that the prop is going to be your biggest issue. The bomb or pod might take damage too so watch for that. If you do it right the bomb shouldn’t go through the prop though as Hondo said.

 

[BayDesigns]

I always forget how durable props are... obviously hitting something isn’t great but it’s not the end of the world, and if it’s the pod that takes damage, that’s not really any great loss, since it’s only cardboard or PLA.