Open Rocket Dual-Deploy Simulation

Just designed my first dual-deploy setup in Open Rocket. In the design settings I've designated the drogue chute to deploy at apogee and the main to deploy at 500 feet. Seemed pretty straightforward, but when I load in a motor (no ejection charge) and run the sim, it's telling me 111 ft/s velocity at deployment. I don't get it. Shouldn't that be closer to 0 ft/s? Can anyone tell me what I'm doing wrong here?

I am new to Open Rocket too. I do not have the answer, but will be interested to see what others say.

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I think you will find that the 111 ft/s is the velocity at the deployment of the main chute, not the drogue chute. When the drogue deploys at apogee it wil be close to 0 ft/s, but not when the main deploys.

If you look at a plot of the flight, you will see that the drogue deploys at apogee (or when ever you programed it), and the main at its programed altitude, at what ever velocity.
The short answer as already stated is you are looking at the main deployment, if it were mine, I would probably increase the size of the drogue a little. (Just my not so humble opinion)

Voyager1 said:

I think you will find that the 111 ft/s is the velocity at the deployment of the main chute, not the drogue chute. When the drogue deploys at apogee it wil be close to 0 ft/s, but not when the main deploys.

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Bingo. And of course. Thanks John and Terry for helping point out the obvious. To satisfy my own curiosity I made the size of the drogue larger and it did indeed change the velocity.

So here's the next question: what would be the ideal descent rate under a drogue chute?

ideal rate depends on the rocket. you want the upper portion of the rocket to remain above the lower portion, it inhales greatly when the upper section tries to take fins off when the main deploys. for my two 3" birds this means a rate of about 55fps.
Rex

Faroutspacenut said:

So here's the next question: what would be the ideal descent rate under a drogue chute?

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As fast as possible, yet just slow enough so that the main chute deploys without damage.
Therefore, the answer will depend on the strength of the main chute's lines and fabric, size and shape of the chute, as well as the weight of the rocket.

For skydivers, in belly-to-earth, a human body free-falls at about 200 km/h (or 120 mph or 176 ft/s) on a ~35 foot chute.
That chute deployment speed, for that chute size and payload weight, is deemed safe.

So on a well constructed chute, 175 ft/s deployment is safe for the chute.
On our budget-minded rocket hobby chutes, I expect a lower deployment speed will be advisable. How much lower - will depend on the chute construction and rocket weight specifics.
100 ft/s?
50 ft/s?

I've personally had good luck with 5# rockets deploying main at ~75 ft/s.

YMMV,
a

I generally go for about 50 ft/s, or 15 m/s down under. As stated above, you have a fair margin, but it does depend on all those factors already mentioned. Use good quality chutes with strong shroud lines.

Great advice, thank you. I'll be taking construction/materials into consideration for sure now.