Login    Register
User Information
Username:
Password:
We are a free and open
community, all are welcome.
Click here to Register
Sponsored
Who is online

In total there are 71 users online :: 5 registered, 0 hidden and 66 guests


Most users ever online was 218 on Wed Dec 07, 2016 6:58 pm

Registered users: Bing [Bot], Exabot [Bot], Google [Bot], MSNbot Media, Yahoo [Bot] based on users active over the past 5 minutes

The Team
Administrators
Global Moderators
global_moderators.png CS

Airsoft bb's not indicating on a chrony. Problem solved.

A place to ask general spud cannon related questions.
Sponsored 
  • Author
    Message

Airsoft bb's not indicating on a chrony. Problem solved.

Unread postAuthor: Gippeto » Sat Nov 29, 2008 5:48 pm

I've been trying to get some velocity readings on a little "project". :)

Specs aren't too important for the question, but what the heck. :D


Barrel: 36" of 9/32" brass tube, .014" wall, fits 6mm airsoft bb's quite well

Chamber: 6" of 3/4" Type M copper

Piston: Machined from nylon with a sealing face of teflon. "Spool" shaped for weight reduction and using a floating o-ring seal

Co-axial configuration

Pilot: The modded blowgun and fittings from my copper gun. The bumper was "borrowed" as well.

Operating pressure: 400psi air

The problem is that the airsoft bb's are not registering on the chrony.

I checked and changed the battery, and verified it was working with a .177 air rifle.

Firing a shot with the air rifle, leaves a fps reading on the chrony. Following up with a shot from the "project" doesn't change the reading indicated.

I am not getting error messages as when only one sensor reads the projectile. (It does however, penetrate ~3/8" into the phone book/backstop. :D )

I am getting a no reading what so ever, on the dozen shots fired thus far.

Anyone have any ideas as to why? :?




Edit: I know Jack had a similar (errors?) problem with a combro chrony and was going to try an F1.

I'm using an F1.
  • 0

Last edited by Gippeto on Mon Dec 01, 2008 2:59 pm, edited 1 time in total.
User avatar
Gippeto
Donating Member
Donating Member
 
Posts: 2394
Joined: Sat Jan 19, 2008 10:14 am
Location: The Great White North...Canada eh!
Reputation: 11

Unread postAuthor: POLAND_SPUD » Sat Nov 29, 2008 6:33 pm

I know it might sound stupid.... but maybe the round has to be made from metal ??
  • 0

Children are the future

unless we stop them now
User avatar
POLAND_SPUD
Chief of Staff
Chief of Staff
 
Posts: 5405
Joined: Sat Oct 13, 2007 4:43 pm
Country: Israel (il)
Reputation: 10

Unread postAuthor: Gippeto » Sat Nov 29, 2008 6:58 pm

At this point, I'll take ANY ideas for consideration. :?

I'm not sure about that, it worked fine when I was testing both the copper gun with marbles, and the pvc gun with marshmallows.

I think the sensors pick up a change in the level of light, but I'm not 100% sure.

Could it BE light related? But then WHY do the .177 pellets get noticed?

They are smaller than the bb's.

The mystery deepens. :?
  • 0

User avatar
Gippeto
Donating Member
Donating Member
 
Posts: 2394
Joined: Sat Jan 19, 2008 10:14 am
Location: The Great White North...Canada eh!
Reputation: 11

Unread postAuthor: THUNDERLORD » Sat Nov 29, 2008 7:01 pm

Just a thought but at that velocity maybe the trajectory is going above the gauge?
Sounds like a cool project. (Pics?) :wink:
But you hacked your copper gun(?) :( 8)
  • 0

-----SPEED,STRENGTH, AND ACCURACY.-----
"Procrastination" is five syllables for "Sloth".
Theopia 8)
Born To Be Alive!

THUNDERLORD
Major General
Major General
 
Posts: 1264
Joined: Fri Mar 28, 2008 1:42 pm
Reputation: 0

Unread postAuthor: Gippeto » Sat Nov 29, 2008 7:25 pm

The chrony is supposed to read up to 7000fps.

If I'm exceeding that,.. I guess you can start bowing now. :lol: :roll:

Seriously, it should be close to mach 1, but no where near the limits of the chrony.

I'll be posting it when I'm happy with it. I still need to give it a polish. :wink:

As to the copper gun, I just "borrowed" the pilot assembly for now.

I have started a new and better copper gun. (Chamber sealing piston with bolt action. :D ) And likely WILL chop up the old one to free up space. :(
  • 0

User avatar
Gippeto
Donating Member
Donating Member
 
Posts: 2394
Joined: Sat Jan 19, 2008 10:14 am
Location: The Great White North...Canada eh!
Reputation: 11

Unread postAuthor: MrCrowley » Sat Nov 29, 2008 7:29 pm

  • 0

User avatar
MrCrowley
Moderator
Moderator
 
Posts: 10207
Joined: Fri Jun 23, 2006 10:42 pm
Location: Auckland, New Zealand
Country: New Zealand (nz)
Reputation: 4

Unread postAuthor: Ragnarok » Sat Nov 29, 2008 7:33 pm

Normally these things work on an infrared beam. Have you tried both with and without diffusers?

It might be possible that the BB isn't blocking the beams for long enough to trip it. A .177 pellet is usually somewhat longer from head to tail than a BB, and I'm guessing, not quite as fast as your project is spitting out BBs (what was the air rifle coming in at?).

After all, the chrony is usually asked to detect projectiles which are rather longer proportional to their speed (and thus block the sensors longer).

Try using a lower pressure (and thus velocity) and see if it starts registering then. If not, obviously it's not that it's too short a blip for the chrony.
  • 0

Does that thing kinda look like a big cat to you?
User avatar
Ragnarok
Chief of Staff
Chief of Staff
 
Posts: 5339
Joined: Tue Dec 19, 2006 8:23 am
Location: The UK
Reputation: 8

Sponsored

Sponsor
 


Unread postAuthor: SEAKING9006 » Sat Nov 29, 2008 7:35 pm

Try using colored BB's, I think it may be made out of the same plastic the little upper spars are. That is, if the one's you're using are white.
  • 0

Completed projects:
CA1 SMSS Basic Inline
CA3 PDAB Airburst Cannon

Current Project: Bolt action rifle (25x140mm + 1in shot)

SEAKING9006
Colonel
Colonel
 
Posts: 734
Joined: Mon Jun 23, 2008 3:20 pm
Location: Texas
Reputation: 0

Unread postAuthor: Gippeto » Sat Nov 29, 2008 7:51 pm

Good ideas, thanks!

I'll try the diffusers tomorrow, and paint my red bb's black.

Lower pressure doesn't sound like as much fun, ( :( ) but I'll try that too.
  • 0

User avatar
Gippeto
Donating Member
Donating Member
 
Posts: 2394
Joined: Sat Jan 19, 2008 10:14 am
Location: The Great White North...Canada eh!
Reputation: 11

Unread postAuthor: rp181 » Sat Nov 29, 2008 8:16 pm

try looking at where the detector's are, and shoot directly above it.
  • 0

User avatar
rp181
Brigadier General
Brigadier General
 
Posts: 1090
Joined: Thu Dec 13, 2007 8:47 pm
Reputation: 0

Unread postAuthor: Ragnarok » Sat Nov 29, 2008 8:19 pm

Gippeto wrote:Lower pressure doesn't sound like as much fun.

It won't be of course, but it's a means to diagnose the problem.
  • 0

Does that thing kinda look like a big cat to you?
User avatar
Ragnarok
Chief of Staff
Chief of Staff
 
Posts: 5339
Joined: Tue Dec 19, 2006 8:23 am
Location: The UK
Reputation: 8

Unread postAuthor: Gippeto » Mon Dec 01, 2008 10:30 am

I have results now. :D

I painted my airsoft bb's black with a sharpie pen, used the diffuser screens, and the indoor light kit.

Readings varied between 1205 and 1239fps. 8)

According to wikipedia, sos in air @ 20C is 1125fps. :D
  • 0

User avatar
Gippeto
Donating Member
Donating Member
 
Posts: 2394
Joined: Sat Jan 19, 2008 10:14 am
Location: The Great White North...Canada eh!
Reputation: 11

Unread postAuthor: Ragnarok » Mon Dec 01, 2008 11:34 am

Gippeto wrote:Readings varied between 1205 and 1239fps.

According to wikipedia, sos in air @ 20C is 1125fps. :D

I'm going to have to ask it, or someone else will - how close were you to the Chrony?
It's not impossible to go supersonic pneumatically, but it's very improbably - and extraordinary claims require extraordinary proof.

Also, you've just made me realise an error in the LRC - now fixed.
  • 0

Does that thing kinda look like a big cat to you?
User avatar
Ragnarok
Chief of Staff
Chief of Staff
 
Posts: 5339
Joined: Tue Dec 19, 2006 8:23 am
Location: The UK
Reputation: 8

Unread postAuthor: jackssmirkingrevenge » Mon Dec 01, 2008 12:54 pm

Oh come on, show us the launcher :)

I did manage to get readings for 6mm BBs with an F1 and they were light yellow, glad you managed to find a solution :)
  • 0

User avatar
jackssmirkingrevenge
Donating Member
Donating Member
 
Posts: 24225
Joined: Thu Mar 15, 2007 11:28 pm
Country: Holy See (Vatican City State) (va)
Reputation: 66

Unread postAuthor: Gippeto » Mon Dec 01, 2008 2:12 pm

@ Rag;

Within roughly 6". I'll be taking a video later to include when I post it.

I trust that will be satisfactory evidence? :)

Coming soon to a thread near you.
  • 0

User avatar
Gippeto
Donating Member
Donating Member
 
Posts: 2394
Joined: Sat Jan 19, 2008 10:14 am
Location: The Great White North...Canada eh!
Reputation: 11

Return to General Spud Cannon Related

Who is online

Registered users: Bing [Bot], Exabot [Bot], Google [Bot], MSNbot Media, Yahoo [Bot]

Reputation System ©'