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 64 users online :: 5 registered, 0 hidden and 59 guests


Most users ever online was 155 on Mon Aug 15, 2016 1:40 am

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

The Team
Administrators
Global Moderators
global_moderators.png CS

More HGDT crap (HGDT vs. Latke, the rematch)

Post questions and info about hybrid (compressed gas with fuel) powered cannons here. This includes discussion about fuels, ratios, ignition systems, build types, safety, and anything else relevant.
Sponsored 
  • Author
    Message

More HGDT crap (HGDT vs. Latke, the rematch)

Unread postAuthor: D_Hall » Mon May 26, 2008 10:46 pm

For those who aren't allergic to reading, I would invite ya'll to visit the HGDT site (see link in my sig), go to the "Design Library," and check out what I've got to say about the L1 and L3.

For those who don't like reading, here are the pretty pictures.

Image
Image
Image


Comments?
  • 0

Simulation geek (GGDT / HGDT) and designer of Vera.
User avatar
D_Hall
Donating Member
Donating Member
 
Posts: 1759
Joined: Thu Feb 07, 2008 7:37 pm
Location: SoCal
Reputation: 6

Unread postAuthor: biggsauce » Mon May 26, 2008 11:00 pm

Whats the verdict? Has the "knee" been explained?
  • 0

User avatar
biggsauce
Captain
Captain
 
Posts: 338
Joined: Thu Jun 07, 2007 9:42 pm
Reputation: 0

Unread postAuthor: D_Hall » Mon May 26, 2008 11:02 pm

Jimmy,

In the other thread you pointed out how poorly HGDT was doing against your standard gun. You said your gun chronos at 300-330 fps while HGDT sim'ed you at (IIRC) 240.

Well, I'm still a bit slow, but it's a lot better (and I can get it over 300 if I play around)....

It is rather odd, though. I used the data from your technical gun (closed chamber experiments) to arrive at flame accelerations and such. If there's ANY gun HGDT ought to model well, it'd be your's.
  • 0

Attachments
jimmy.gif
jimmy.gif (30.41 KiB) Viewed 893 times
Last edited by D_Hall on Tue May 27, 2008 12:34 am, edited 2 times in total.
Simulation geek (GGDT / HGDT) and designer of Vera.
User avatar
D_Hall
Donating Member
Donating Member
 
Posts: 1759
Joined: Thu Feb 07, 2008 7:37 pm
Location: SoCal
Reputation: 6

Unread postAuthor: D_Hall » Mon May 26, 2008 11:05 pm

biggsauce wrote:Whats the verdict? Has the "knee" been explained?

No, but it does show up in all the Latke data (to varying degrees).
  • 0

Simulation geek (GGDT / HGDT) and designer of Vera.
User avatar
D_Hall
Donating Member
Donating Member
 
Posts: 1759
Joined: Thu Feb 07, 2008 7:37 pm
Location: SoCal
Reputation: 6

Unread postAuthor: D_Hall » Tue May 27, 2008 8:14 am

D_Hall wrote:It is rather odd, though. I used the data from your technical gun (closed chamber experiments) to arrive at flame accelerations and such. If there's ANY gun HGDT ought to model well, it'd be your's.


Last night while I was laying in bed I think it hit me...


I used the technical gun data to study the static chamber flame accelerations. I did NOT look at those shots with the fan on (d'oh!). OK... Need to go back and re-examine fan-on scenarios.

Note: It is pretty obvious (to me) that it's a flame acceleration issue based on two things.

1) Throw in a multiple igniters and your gun models fine (so I just need to burn the propellant faster!).
2) I'm handling the Latke L1 very well... and while we don't know for sure I suspect it to be a static chamber at the time of firing.
  • 0

Simulation geek (GGDT / HGDT) and designer of Vera.
User avatar
D_Hall
Donating Member
Donating Member
 
Posts: 1759
Joined: Thu Feb 07, 2008 7:37 pm
Location: SoCal
Reputation: 6

Unread postAuthor: jimmy101 » Tue May 27, 2008 1:21 pm

D_Hall

You are getting all three of Latke's chamber / ammo combinations essentially perfectly. The small disagreements look to be well within the accuracy (shot to shot variability) of Latke's data.

...and while we don't know for sure I suspect it to be a static chamber at the time of firing.

You mean you believe the fan was off and the gases more or less stationary when the gun was fired?

Let me dust off my "standard gun" and chrony it again. I'll measure the spud masses and try to get a rough measurement of the static and dynamic friction as well.
  • 0

Image

jimmy101
Lieutenant General
Lieutenant General
 
Posts: 3128
Joined: Wed Mar 28, 2007 9:48 am
Location: Greenwood, Indiana
Country: United States (us)
Reputation: 7

Unread postAuthor: D_Hall » Tue May 27, 2008 7:55 pm

jimmy101 wrote:You mean you believe the fan was off and the gases more or less stationary when the gun was fired?

Yes.

Let me dust off my "standard gun" and chrony it again. I'll measure the spud masses and try to get a rough measurement of the static and dynamic friction as well.

That'd be much appreciated.
  • 0

Simulation geek (GGDT / HGDT) and designer of Vera.
User avatar
D_Hall
Donating Member
Donating Member
 
Posts: 1759
Joined: Thu Feb 07, 2008 7:37 pm
Location: SoCal
Reputation: 6

Sponsored

Sponsor
 


Unread postAuthor: SpudFarm » Wed May 28, 2008 9:00 am

i will get to you with some results on PM on the GB hybrid when it is done.
  • 0

"Made in France"
- A spud gun insurance.
User avatar
SpudFarm
Donating Member
Donating Member
 
Posts: 2563
Joined: Sat Nov 04, 2006 9:39 am
Location: Norway Trondheim area
Reputation: 0

Return to Hybrid Cannon Discussion

Who is online

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

Reputation System ©'