Japanese Parachute deploy system

[RaZias]

Were is a picture of a parachute deploy system.
It doesn´t use TomyTimers.

What happens is that when the rocket achives zero speed in the maximum height the small weight will still go forward (like the projection force a driver feels in a fast brake).

That weight will hit something (maybe the little hook) that will release the parachute.

hatchchute.jpg (31.16 KiB) Viewed 265 times

[RaZias]

It´s a Japanese system and in fact it works, I just don´t remember the site but I saved the picture months ago.

In the other side of the world they don´t use TomyTimers.

[Tim Chen]

I wish I could read Japanese so I could understand how it works. It's very well drawn, but I don't understand the principle of how it should work.

[thampson]

anyone able to translate this ?

Im not sure at what point it would deploy though. If you look at any of the simulators you will see after a large positive G load at liftoff, the rocket will get negative G's way before apogee.

I guess it will be a matter of where is the point that the force from the air resistance keeping the slider at the bottom is overcome by the negative G's acting on the rocket (and the slider) to get it to slide up and hit the release latch

-todd-
HHWRSA

[dongfang]

Hi,

anyone able to translate this ?

Had it been Chinese, sure. But not Japanese..

Anyway .. at rocket deceleration, the lead bead will slide up the rod. It will bang into the thing on the rod above it, and hammer the lower end of the rod out of the bracket it is mounted in.

Regards
Soren

[andicirk]

ok , ive copied the image and im asking my freinds girlfreind to translate it , first into french then ill translate it into english, but if any one else can do it please do it as well, looking at the picture the tolerances would have to be very well made, ie enough weight to gard the inertia,and activate the release and overcome the friction of bar........., ill try my best my end

[andicirk]

before i get the translation here are just a few ideas on how it works from just looking at the picture, i think the parachute will have a spring loaded deployement system at the end of the deployement cycle any way ive tried to explain on the image below

[andicirk]

eeek , sorry i forgot to say this , the point the most important within this system is the point of security , this needs to release the weight before the rocket reaches its maximum height (as there wold be no inertia left for the weight to utilise , ( flash of insperation) no im wrong this is there to hold the weight in place just until there rocket turns and nose dives to the ground , then the weight falls and "voila " your parachute opens ....

damn simplicity in its best using the thing we are fighting against to open the chute ....... gravity

[Andromeda]

Can someone confirm for me that this system is a working design? Is this the common practice in Japan? Like we use Tomy timer?

[RaZias]

Can someone confirm for me that this system is a working design? Is this the common practice in Japan? Like we use Tomy timer?

It´s a working design because I read it in a site (I just don´t know site...).
It´s a story of an american water-rocketter that visited Japan and he exchanged ideas with Japanese.
They used this method and he teached them how to use TomyTimers.

Other method they used was the nose-apogge in a diagonal launch.

[RaZias]

Were is the site:

http://dogrocket.home.mindspring.com/Wa ... eport.html

It says:
There is a spring-biased hatch near the tail of the rocket that contains the parachute. It is latched closed with a rod that extends through a hole in the latch. The rod is mounted parallel to the body of the rocket, and has a sliding weight, a fishing weight, on it. When the rocket tips at apogee, the weight slides forward, hitting a stop on the rod and thus pulling the rod forward a bit, enough to release the hatch, and thus the parachute. Here's a diagram, again scanned from a book.


Anyway, they have other system:

There are two parachute systems in wide use. One is Orii-san's invention, a "set the top part on the bottom part and launch" system, where air pressure and/or acceleration keep that two sections together until near apogee (remember that all japanese rockets are "nozzled down" so the acceleration is smooth and slow). There are some nice refinements here: the top section is long, more than just the nose, and there are two parachutes, one for each section. At the joint, each section is wrapped once with weather stripping. This provides a nice resilient "shelf" at the joint, which (I think) really helps them stay together. Here's a line drawing of this system, scanned from one of my Japanese water rocket books:

oriichute.jpg (31.22 KiB) Viewed 212 times

[andicirk]

just found the original article i dont know if it makes it any clearer........

http://dogrocket.home.mindspring.com/Wa ... eport.html

[Tim Chen]

I don't know if any of these will work for my team because we are using full bottle throat nozzles and we get a lot of Gs of acceleration and deceleration.
But, it's interesting to see how different cultures tackled the same problems in isolation from each other.

[Brian]

i was testing my gravity deployment system on a 2L 22mm nozzle rocket that has high negative G's after the thrust phase. first i tested the japanese style gravity deployment system but it failed after the thust phase. i'm going to launch my newest gravity deployment system today if it gets sunny.