Acceptable descent profile?

This forum is for non-members to ask questions about our competitions. Please check our FAQ page before you ask.
User avatar
bugwubber
WRA2 Member
WRA2 Member
Posts: 1087
Joined: Wed Dec 19, 2012 2:47 am

Acceptable descent profile?

Post by bugwubber »

WRA, just wanted to get your take on this- this is a non ballistic recovery rocket. No chute, just falls sideways. Is this slow enough?
HK-A_2014331_129.png
HK-A_2014331_129.png (147.28 KiB) Viewed 68 times
Bugwubber

Team S.P.E.W.
User avatar
WRA2
Site Admin
Site Admin
Posts: 1089
Joined: Sat Dec 30, 2006 11:30 pm

Re: Acceptable descent profile?

Post by WRA2 »

bugwubber wrote:WRA, just wanted to get your take on this- this is a non ballistic recovery rocket. No chute, just falls sideways. Is this slow enough?
HK-A_2014331_129.png

The rule states 33 feet per second at touchdown. Any kind of recovery that achieves that speed is allowed (chute, steamer, wing/glider, tumble, side glider, etc.)

28.95 feet per second would meet the criteria.

All launched parts of rocket which travel over 6 meters (20 feet) in altitude must have a recovery system which limits their descent rate at time of touchdown at ground level to a maximum velocity of 10 meters/second (33 feet per second)
Lisa Walker,
:WRA2: Forum Administrator. :WRA2:
:WRA2:The Water Rocket Achievement World Record Association :WRA2:
User avatar
bugwubber
WRA2 Member
WRA2 Member
Posts: 1087
Joined: Wed Dec 19, 2012 2:47 am

Re: Acceptable descent profile?

Post by bugwubber »

WRA2 wrote:
bugwubber wrote:WRA, just wanted to get your take on this- this is a non ballistic recovery rocket. No chute, just falls sideways. Is this slow enough?
HK-A_2014331_129.png

The rule states 33 feet per second at touchdown. Any kind of recovery that achieves that speed is allowed (chute, steamer, wing/glider, tumble, side glider, etc.)

28.95 feet per second would meet the criteria.

All launched parts of rocket which travel over 6 meters (20 feet) in altitude must have a recovery system which limits their descent rate at time of touchdown at ground level to a maximum velocity of 10 meters/second (33 feet per second)
Great! Thanks.
Bugwubber

Team S.P.E.W.
User avatar
Water Rocket Expert
WRA2 Member
WRA2 Member
Posts: 622
Joined: Fri Nov 22, 2013 10:39 am

Re: Acceptable descent profile?

Post by Water Rocket Expert »

Oh no, here he goes getting a record!

WRA2, would my altimeter work for testing descent rate on a unreinforced flight. It is peak altitude but it has descent rate feature.
Water Rocket Expert
I'm 20
Maryland
"Anyone who has never made a mistake has never tried anything new." -Albert Einstein
User avatar
WRA2
Site Admin
Site Admin
Posts: 1089
Joined: Sat Dec 30, 2006 11:30 pm

Re: Acceptable descent profile?

Post by WRA2 »

Water Rocket Expert wrote:Oh no, here he goes getting a record!

WRA2, would my altimeter work for testing descent rate on a unreinforced flight. It is peak altitude but it has descent rate feature.
If you combine it with a good simulator and or video of the flight. You know the peak altitude. If you took video or used an onboard camera (better) you can figure the time the rocket took to descend from apogee to the ground and figure out feet per second from that.
Lisa Walker,
:WRA2: Forum Administrator. :WRA2:
:WRA2:The Water Rocket Achievement World Record Association :WRA2:
User avatar
bugwubber
WRA2 Member
WRA2 Member
Posts: 1087
Joined: Wed Dec 19, 2012 2:47 am

Re: Acceptable descent profile?

Post by bugwubber »

Water Rocket Expert wrote:Oh no, here he goes getting a record!

WRA2, would my altimeter work for testing descent rate on a unreinforced flight. It is peak altitude but it has descent rate feature.
Well, whether we do or not, in this case I'm more interested in making sure the design conforms to WRA safety rules before I start telling others how to make it.
Bugwubber

Team S.P.E.W.
User avatar
Water Rocket Expert
WRA2 Member
WRA2 Member
Posts: 622
Joined: Fri Nov 22, 2013 10:39 am

Re: Acceptable descent profile?

Post by Water Rocket Expert »

WRA2 wrote:
Water Rocket Expert wrote:Oh no, here he goes getting a record!

WRA2, would my altimeter work for testing descent rate on a unreinforced flight. It is peak altitude but it has descent rate feature.
If you combine it with a good simulator and or video of the flight. You know the peak altitude. If you took video or used an onboard camera (better) you can figure the time the rocket took to descend from apogee to the ground and figure out feet per second from that.
So does that mean we don't have to have onboard video, just good ground based video? That would be awesome because the camera I am using right now is too heavy for a 2 liter rocket.
Water Rocket Expert
I'm 20
Maryland
"Anyone who has never made a mistake has never tried anything new." -Albert Einstein
User avatar
WRA2
Site Admin
Site Admin
Posts: 1089
Joined: Sat Dec 30, 2006 11:30 pm

Re: Acceptable descent profile?

Post by WRA2 »

Water Rocket Expert wrote:
WRA2 wrote:
Water Rocket Expert wrote:Oh no, here he goes getting a record!

WRA2, would my altimeter work for testing descent rate on a unreinforced flight. It is peak altitude but it has descent rate feature.
If you combine it with a good simulator and or video of the flight. You know the peak altitude. If you took video or used an onboard camera (better) you can figure the time the rocket took to descend from apogee to the ground and figure out feet per second from that.
So does that mean we don't have to have onboard video, just good ground based video? That would be awesome because the camera I am using right now is too heavy for a 2 liter rocket.
Your question was on how to determine the descent rate of your rocket.

Cameras are required onboard for all competitions except the flight duration:

http://www.wra2.org/WRA2_Class_C_Rules.php

No exceptions.
Lisa Walker,
:WRA2: Forum Administrator. :WRA2:
:WRA2:The Water Rocket Achievement World Record Association :WRA2:
User avatar
Water Rocket Expert
WRA2 Member
WRA2 Member
Posts: 622
Joined: Fri Nov 22, 2013 10:39 am

Re: Acceptable descent profile?

Post by Water Rocket Expert »

Thanks! I probably should have looked at the rules first.
Water Rocket Expert
I'm 20
Maryland
"Anyone who has never made a mistake has never tried anything new." -Albert Einstein
User avatar
U.S. Water Rockets1
WRA2 Member
WRA2 Member
Posts: 1778
Joined: Sat Feb 03, 2007 3:24 pm

Re: Acceptable descent profile?

Post by U.S. Water Rockets1 »

If you are interested in the descent rate only at the moment of landing, you can also use a reference object in the ground based video. You can see at that frame number the rocket is level with some object of a known height (you can measure it at any time) and then count the frames it takes to reach the ground from that point. The video file will have a set number of frames per second, you can figure out how many seconds it took to travel the known distance and divide to get feet per second.
Team U.S. Water Rockets
Visit USWaterRockets.com
Visit our Blog
Tune in to our YouTube Channel
Visit our Facebook page
Visit our Twitter Page
Opportunity is missed by most people because it is dressed in overalls and looks like work. --Thomas Edison
User avatar
Water Rocket Expert
WRA2 Member
WRA2 Member
Posts: 622
Joined: Fri Nov 22, 2013 10:39 am

Re: Acceptable descent profile?

Post by Water Rocket Expert »

U.S. Water Rockets1 wrote:If you are interested in the descent rate only at the moment of landing, you can also use a reference object in the ground based video. You can see at that frame number the rocket is level with some object of a known height (you can measure it at any time) and then count the frames it takes to reach the ground from that point. The video file will have a set number of frames per second, you can figure out how many seconds it took to travel the known distance and divide to get feet per second.
I know, although I am trying to find average FPS, that is why I am using my altimeter to shorten the work.
Water Rocket Expert
I'm 20
Maryland
"Anyone who has never made a mistake has never tried anything new." -Albert Einstein
User avatar
Alien Space Agency
WRA2 Member
WRA2 Member
Posts: 163
Joined: Sun Nov 15, 2015 7:32 am

Re: Acceptable descent profile?

Post by Alien Space Agency »

Wait, PA altimeters are acceptable with descent rate?
Nothing can stop a curious mind from inventing- Anonymous
User avatar
bugwubber
WRA2 Member
WRA2 Member
Posts: 1087
Joined: Wed Dec 19, 2012 2:47 am

Re: Acceptable descent profile?

Post by bugwubber »

Alien Space Agency wrote:Wait, PA altimeters are acceptable with descent rate?
You have to have an onboard camera so descent rate can be derived from elapsed time.
Bugwubber

Team S.P.E.W.
User avatar
Alien Space Agency
WRA2 Member
WRA2 Member
Posts: 163
Joined: Sun Nov 15, 2015 7:32 am

Re: Acceptable descent profile?

Post by Alien Space Agency »

But logging altimeters are still required, right?
Nothing can stop a curious mind from inventing- Anonymous
User avatar
WRA2
Site Admin
Site Admin
Posts: 1089
Joined: Sat Dec 30, 2006 11:30 pm

Re: Acceptable descent profile?

Post by WRA2 »

for our altitude competitions logging altimeters are required for the following classes (A, B, and E). Peak altimeters are allowed for Class D.
Lisa Walker,
:WRA2: Forum Administrator. :WRA2:
:WRA2:The Water Rocket Achievement World Record Association :WRA2: