Creating a Silent Dartboard: Physics & Solutions

[boffinwannabe]

so what started out as a quick project to silence my dartboard has ended up wondering what would be the physics involved in creating a silent dartboard. It has to use a standard board so the board can't be modded in terms of its materials. Now i guess the answer is to dissipate the energy as far as possible through the board itself into a another medium? For example if the board was fitted with rear springs that took up the impact would that result in less dart 'thump'? As for the stand, would it need to be on a spring that again allowed for movement?

 

[CWatters]

Interesting question. The quicker the dart stops the greater the impact force on the board so one option would probably be to modify the darts so they have very narrower points like a hypodermic needle and penetrate further into the board. However that's probably also against the rules.

I doubt springs would reduce the initial impact because the mass of the dartboard is large compared to the dart. eg The board may not move much so the springs don't absorb much of the energy. I don't think you would want the board to move too much anyway because then the darts wouldn't penetrate as far into the board. However the springs may work by preventing the shockwave coupling into the wall. It may sound just as loud in the room but quieter next door.

 

[boffinwannabe]

Thank you for the reply. I was afraid people would think i was trolling but actually I am finding it a tough problem. The narrow point was not something i thought about, thanks. I guess in practice it means keep the darts ultra sharp. Will be interesting to actually test the difference between a blunt and highly sharpened dart.

 

[AlephZero]

You can't change the kinetic energy in the dart after it has been thrown, and you can't change the fact that all the KE will be absorbed somehow when the dart stops.

What you can change is how much of the KE gets radiated as pressure waves into the air, i.e. noise. I would expect most of the noise comes from the impulse response of the structure the dartboard is mounted on, especially if it is a flat panel that has its own modes of vibration in the audio frequency range.

You can find out the best you could achieve, by taking the board off its mounting and propping it against something soft (e.g. a chair with a cushion) and throwing a dart at it.

It's hard to make any specific suggestions about how to damp out noise from what the board is mounted on without knowing more about it (e.g. seeing a picture of it or a link to where you bought it from). If the mounting itself is vibrating, fixing it to the wall with springs etc won't make much difference.

 

[sophiecentaur]

so what started out as a quick project to silence my dartboard has ended up wondering what would be the physics involved in creating a silent dartboard. It has to use a standard board so the board can't be modded in terms of its materials. Now i guess the answer is to dissipate the energy as far as possible through the board itself into a another medium? For example if the board was fitted with rear springs that took up the impact would that result in less dart 'thump'? As for the stand, would it need to be on a spring that again allowed for movement?

IS someone giving you a hard time from playing darts into the small hours?
Best thing would be to mount the board by hanging it from a long string and letting it rest on a very soft fibre mat (or pillow?). You will hear the bang of impact in the room but the noise will not propagate through the walls, which must be the source of annoyance for your neighbours, I reckon.
You could also reduce the transmitted noise by mounting the board itself on a really massive metal plate (still suspended) and gluing it well, over the whole area. Also, the sharper the darts are, the better, as they will travel further into the surface and extend the time of impact, producing a longer, lower impulse.

 

[boffinwannabe]

yes neighbour complaining and this is in the middle of the day! i already have the board on a portable darts stand so nothing goes through the wall. I have noise absorbing panels on the wall which takes the sharp echoy part of the sound away. But the people downstairs still moan. However looking around the net I've seen this is a problem a lot of people have with their darts setup and i began wondering if a board holding apparatus can be designed in such a way as to further reduce the sound.

 

[sophiecentaur]

The only solution is to have a rigid, massive dartboard (I mean lots of Mass and not 10m across!) which is decoupled from the surrounding by a 'lossy', bungy medium. Walls and floors transmit sound very well so it must not even rest directly on a hard chair. To reduce sound traveling through the air you could use heavy furnishings around the board, like a cubicle or large diameter tube with sides lined with carpet, blanket etc. etc.

I guess you could try for some sort of sound cancelling system, with a microphone placed right on the board (to detect the vibrations and amplifier / loudspeaker right behind it. This would need careful layout to avoid howl-round, of course, but if you are electronically inclined it could be fun.
I think the essential thing is that you spend so much time on this project that it keeps you away from the actual dart playing. That would keep your neighbours happy.
Failing that, you could take up Grand Theft Auto instead of darts.

You could, perhaps, challenge your neighbours as to how loud you are actually being. Get of them to throw darts at your board whilst you are in their flat, listening. Merely making enough noise to be 'detected' doesn't actually constitute a 'nuisance' for a reasonable person. But that's all a social matter and not Physics.

I notice they are downstairs - so a thick insulating mat could help.