On 12/26/2021 5:45 AM, Clive Arthur wrote:> On 26/12/2021 08:17, Don Y wrote: > <snip> >> >> A slug of *water* is almost ideal in that it "disappears" after it >> makes contact (hit *or* miss). And, range could be adjusted directly >> via (water) pressure. >> >> But, pretty messy. It would also require a higher launch velocity to >> remain intact in transit (a stream wouldn't be acceptable) >> >> And, would likely be difficult to make visible (unless you relied >> entirely on the final "splash") > > Snowballs.Snowballs would be excellent! But, I'm not sure how easy it would be to make a machine that could form them, get them firm enough to ensure they don't disintegrate in the launch process and ensure they don't become (dangerous) "ice balls".> But messy. Is there something with similar mechanical properties which doesn't > melt? That way you could form it into different sizes as needed.Are you assuming size can be used as a control variable? I.e., make a fixed strength throwing arm and vary the weight of the projectile to adjust range? I'm assuming (at design/manufacture time) that you can quantify the behavior of the mechanism with a specific projectile and that it will remain repeatable (with that type of projectile). So, you can "learn" how to make a 12 foot toss. And, prior to design release, can adjust the mechanism or projectile to improve the control sensitivity/range to that which you need. ("Hmmm... throwing mechanism is too strong! Even on the lowest control setting, projectiles fly 35 feet! Let's try making heavier projectiles -- or, crippling the throwing arm...")
Short range targeting
Started by ●December 25, 2021
Reply by ●December 26, 20212021-12-26
Reply by ●December 26, 20212021-12-26
On Sunday, December 26, 2021 at 8:51:58 AM UTC-6, Don Y wrote:> On 12/26/2021 5:45 AM, Clive Arthur wrote: > > On 26/12/2021 08:17, Don Y wrote: > > <snip> > >> > >> A slug of *water* is almost ideal in that it "disappears" after it > >> makes contact (hit *or* miss). And, range could be adjusted directly > >> via (water) pressure. > >> > >> But, pretty messy. It would also require a higher launch velocity to > >> remain intact in transit (a stream wouldn't be acceptable) > >> > >> And, would likely be difficult to make visible (unless you relied > >> entirely on the final "splash") > > > > Snowballs. > Snowballs would be excellent! But, I'm not sure how easy it > would be to make a machine that could form them, get them firm > enough to ensure they don't disintegrate in the launch process > and ensure they don't become (dangerous) "ice balls". > > But messy. Is there something with similar mechanical properties which doesn't > > melt? That way you could form it into different sizes as needed. > Are you assuming size can be used as a control variable? I.e., > make a fixed strength throwing arm and vary the weight of the > projectile to adjust range? > > I'm assuming (at design/manufacture time) that you can quantify the > behavior of the mechanism with a specific projectile and that it > will remain repeatable (with that type of projectile). So, you can > "learn" how to make a 12 foot toss. > > And, prior to design release, can adjust the mechanism or projectile > to improve the control sensitivity/range to that which you need. > > ("Hmmm... throwing mechanism is too strong! Even on the lowest > control setting, projectiles fly 35 feet! Let's try making heavier > projectiles -- or, crippling the throwing arm...")How about a mini basketball? Maybe fill it with something besides air if you need a little more weight.
Reply by ●December 26, 20212021-12-26
On 12/26/2021 8:02 AM, Dean Hoffman wrote:>> And, prior to design release, can adjust the mechanism or projectile >> to improve the control sensitivity/range to that which you need. >> >> ("Hmmm... throwing mechanism is too strong! Even on the lowest >> control setting, projectiles fly 35 feet! Let's try making heavier >> projectiles -- or, crippling the throwing arm...") > > How about a mini basketball? Maybe fill it with something besides > air if you need a little more weight.There are myriad choices for projectiles. The problem is coming up with a "system" (projectile + projector) that is repeatable. I.e., so a *second* "mini basketball" performs identically to the first for a given set of "projector controls". (because you can't see where THIS projectile lands but, can be reasonably sure as to where it *should* have landed, based on earlier "design assessment") A basketball player learns how much force is necessary to throw the ball the estimated distance to the hoop (or, another player). He does this by practicing -- shooting hoops to train his muscles and vision with a "representative ball". His skill then boils down to how well he can estimate that toss and execute the corresponding amount of throwing force. If the ball could suddenly changed weight (or aerodynamic properties), his skill would be for naught. [He can also *see* the results of his tosses and make dynamic adjustments to his estimating/throwing. Imagine what a game would be like if he could only know if he'd made the shot, or missed (no information as to whether he was long, short or off to one side or the other)]
Reply by ●December 26, 20212021-12-26
In article <sq8e3h$fmo$1@dont-email.me>, blockedofcourse@foo.invalid says...> > I want to "hit" a fixed spot with a physical object over > relatively short distances (< ~20 ft). > > This must not present a danger to nearby bystanders (in the > event of a "misfire"). "Weapons" are out of the question. > > And, the object must be of sufficient size to be clearly > visible in transit. This also suggests a low transit > velocity. > > I figure I need a bit of mass to ensure aerodynamic > effects don't bugger the calculations. E.g., a softball > would be better than a softball-sized hollow ball > which might exhibit more nonlinear behaviors as it > transits from projectile to ballistic motion. > > The target is (effectively) a "spot on the floor". > I.e., not a vertical "hoop" to pass through (like > goalposts in soccer). > > Accelerating a significant mass would likely prove to > be a challenge so "lobbing" the object seems more > practical. It would also *seem* to be more tolerant > of aiming issues than something HOPING to travel in a > straight line (like a bullet). > > So, conceptually, a tube ("barrel") to guide the > initial segment of flight and some sort of mechanism > to propel the object from the tube. > > Pneumatic, hydraulic, mechanical, etc. > > Will the control over the propulsive force be the tougher > challenge or the precise aiming of the launch tube? > > [You are given (r,theta) to target and no feedback as > to proximity of strike -- unless a direct strike. The > target -- or launcher -- will move after each attempt] > > Of course, "you" is a machine...Build a ramp similar to a ski jump. Use a golf ball and you can adjust the angle of the ramp and how far up you let the golf ball go from. You can probably cut a PVC pipe in half long ways and use an elbow of 45 deg at the bottom. Or do not cut the pipe but put holes in every 6 inches or so to drop the ball in.
Reply by ●December 26, 20212021-12-26
On 12/25/2021 6:47 PM, Don Y wrote:> I want to "hit" a fixed spot with a physical object over > relatively short distances (< ~20 ft). How about a tennis ball? Solenoid launch it, easily adjusted power to solenoid, ( voltage control or charge on a capacitor). Provide an arch type flight, less likely to have the speed to hurt anyone. Add a rotating mount. Might have to qualify your tennis balls for constancy. :-) Mikek -- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus
Reply by ●December 26, 20212021-12-26
On Sat, 25 Dec 2021 17:47:31 -0700, Don Y <blockedofcourse@foo.invalid> wrote:>I want to "hit" a fixed spot with a physical object over >relatively short distances (< ~20 ft). > >This must not present a danger to nearby bystanders (in the >event of a "misfire"). "Weapons" are out of the question. > >And, the object must be of sufficient size to be clearly >visible in transit. This also suggests a low transit >velocity. > >I figure I need a bit of mass to ensure aerodynamic >effects don't bugger the calculations. E.g., a softball >would be better than a softball-sized hollow ball >which might exhibit more nonlinear behaviors as it >transits from projectile to ballistic motion. > >The target is (effectively) a "spot on the floor". >I.e., not a vertical "hoop" to pass through (like >goalposts in soccer). > >Accelerating a significant mass would likely prove to >be a challenge so "lobbing" the object seems more >practical. It would also *seem* to be more tolerant >of aiming issues than something HOPING to travel in a >straight line (like a bullet). > >So, conceptually, a tube ("barrel") to guide the >initial segment of flight and some sort of mechanism >to propel the object from the tube. > >Pneumatic, hydraulic, mechanical, etc. > >Will the control over the propulsive force be the tougher >challenge or the precise aiming of the launch tube? > >[You are given (r,theta) to target and no feedback as >to proximity of strike -- unless a direct strike. The >target -- or launcher -- will move after each attempt] > >Of course, "you" is a machine...Ping-pong balls can be aimed well and aren't very dangerous. I once played with the world's 16th best player. I couldn't return a single serve and his shots did bruise. He applied so much spin that the balls hit my paddle and exited at 90 degrees, typically hitting the ceiling. He was a not very good EE. I also took a college course under the world's #1 doubles badminton player. His rule was that if anyone ever retuned one of his shots, they would get an A and not have to show up any more. Nobody ever did. -- I yam what I yam - Popeye
Reply by ●December 26, 20212021-12-26
On 12/26/2021 9:07 AM, amdx wrote:> On 12/25/2021 6:47 PM, Don Y wrote: >> I want to "hit" a fixed spot with a physical object over >> relatively short distances (< ~20 ft). > > How about a tennis ball?Tennis ball is ideal size for visibility, etc. But, bounces a lot. So, detecting if it has "hit" the target becomes problematic (did it hit the target or *bounce* into it?) This is the appeal of something like a beanbag -- it just *sits* where thrown (more or less). E.g., if you allow for the transit to remain valid after the ground has been contacted, then why not just *roll* the ball in a particular direction and "claim" to have hit anything that it rolls over along the way? :>> Solenoid launch it, easily adjusted power to solenoid, ( voltage control or > charge on a capacitor).But, would it? That was my point behind asking about control over the propulsive force... *if* the projectile (tennis ball in your case) is a "repeatable" unit, can you deliver it to the same point repeatably (just by repeating the "adjusted power to solenoid")?> Provide an arch type flight, less likely to have the speed to hurt anyone.Yes. "lob" not "throw"/shoot.> Add a rotating mount. Might have to qualify your tennis balls for constancy. :-)Yes, as the shooter is not assured that the target will be in the direction the "gun" currently points (r,theta).
Reply by ●December 26, 20212021-12-26
On 12/26/2021 8:38 AM, Ralph Mowery wrote:> In article <sq8e3h$fmo$1@dont-email.me>, blockedofcourse@foo.invalid > says... >> >> I want to "hit" a fixed spot with a physical object over >> relatively short distances (< ~20 ft). >> >> This must not present a danger to nearby bystanders (in the >> event of a "misfire"). "Weapons" are out of the question. >> >> And, the object must be of sufficient size to be clearly >> visible in transit. This also suggests a low transit >> velocity. >> >> I figure I need a bit of mass to ensure aerodynamic >> effects don't bugger the calculations. E.g., a softball >> would be better than a softball-sized hollow ball >> which might exhibit more nonlinear behaviors as it >> transits from projectile to ballistic motion. >> >> The target is (effectively) a "spot on the floor". >> I.e., not a vertical "hoop" to pass through (like >> goalposts in soccer). >> >> Accelerating a significant mass would likely prove to >> be a challenge so "lobbing" the object seems more >> practical. It would also *seem* to be more tolerant >> of aiming issues than something HOPING to travel in a >> straight line (like a bullet). >> >> So, conceptually, a tube ("barrel") to guide the >> initial segment of flight and some sort of mechanism >> to propel the object from the tube. >> >> Pneumatic, hydraulic, mechanical, etc. >> >> Will the control over the propulsive force be the tougher >> challenge or the precise aiming of the launch tube? >> >> [You are given (r,theta) to target and no feedback as >> to proximity of strike -- unless a direct strike. The >> target -- or launcher -- will move after each attempt] >> >> Of course, "you" is a machine... > > Build a ramp similar to a ski jump. Use a golf ball and you can adjust > the angle of the ramp and how far up you let the golf ball go from. You > can probably cut a PVC pipe in half long ways and use an elbow of 45 deg > at the bottom. Or do not cut the pipe but put holes in every 6 inches > or so to drop the ball in.I don't think gravity, alone, would create enough momentum to carry the ball much beyond the end of the ramp. (e.g., think ~20 ft).
Reply by ●December 26, 20212021-12-26
On Sunday, 26 December 2021 at 00:41:17 UTC-8, Don Y wrote: ... How about this for some inspiration? https://www.youtube.com/watch?v=sZm9ZEpvolw kw
Reply by ●December 26, 20212021-12-26
Martin Brown wrote:> On 26/12/2021 07:30, Rick C wrote: >> On Saturday, December 25, 2021 at 10:01:03 PM UTC-5, Jasen Betts wrote: >>> On 2021-12-26, Don Y <blocked...@foo.invalid> wrote: >>>> I want to "hit" a fixed spot with a physical object over >>>> relatively short distances (< ~20 ft). >>>> Accelerating a significant mass would likely prove to >>>> be a challenge so "lobbing" the object seems more >>>> practical. It would also *seem* to be more tolerant >>>> of aiming issues than something HOPING to travel in a >>>> straight line (like a bullet). >>>> >>>> So, conceptually, a tube ("barrel") to guide the >>>> initial segment of flight and some sort of mechanism >>>> to propel the object from the tube. >>> mini trebuchet >> >> + 1 > > Yes. They are great fun. There is a bloke near me who has scale model > fully operational trebuchet able to lob a water melon about 200m! > > It is very impressive and apart from the beam quite compact. When things > return to normal I might try and catch up with him again to film it in > action. He does charity gigs with it from time to time in normal summers > - needs a *lot* of space. (and careful crowd control down range) > > This is the biggest one I have seen online and representative of the > sort of design that would work. Camera work is pretty good too: > > https://www.youtube.com/watch?v=UdGqggET0o4 >See you and raise you: https://www.youtube.com/watch?v=M1iPxY3FYNE At Warwick Castle there's a copy of Edward 1's Warwolf. Here's a similar example; https://www.youtube.com/watch?v=4_iIfZH33MA Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com
