Safe parachuting

[Kimberly]

I just lost my first kerbonaut.

The craft got above the atmosphere, but circularization went too slowly. I realized I'd have to abort the mission, so I separated the command pod from the fuel tank (bottom) and satellite (top) at 65,000 meters, deploying the two MK2-R radial parachutes immediately afterwards. I oriented myself retrograde on the path through the atmosphere, and the two chutes seemed to be slowing me down nicely...but at 500 meters, the chutes opened fully and the force tore off the chutes and the ASAS module still attached to the pod. With no parachutes, the pod splashed hard on impact.

The flight report listed a simultaneous "structural failure" of the parachutes, ASAS module and docking clamp. The craft experienced a maximum of 8.6G.

So what did I do wrong? Was my landing strategy the problem, or should I have used more parachutes? I've had feather-soft landings with a single Mk25, but I had to use the radials in this case because of the attached satellite. Alternate design suggestions would also be welcome.

Edited June 26, 2013 by Kimberly

[Klingon Admiral]

First question: 4x physical time acceleration? It does horrible things to parachutes from time to time.

Second question: Were where your chutes attached exactly? It often happens that the G-forces of opening chutes rip a spacecraft apart, especially if the structure is not reinforced with struts.

That said, I have generally made bad experiences with the radial chutes on the small command pod, I finally resortet on attaching two small chutes on "horns" for my Gemini-esque missions.

[RocketPilot573]

It sounds like you where just going too fast. Try added more parachutes and struts to keep the ship in one piece. Also, I often have to use an engine to slow the craft down to around 80 m/s right before 500 meters. Finally, one last trick is to use the Drogue chutes along with normal ones. Those ones open at 2500 meters so that the deceleration is not as sudden and violent.

[Kimberly]

They were attached directly to the sides of the (cone-shaped) command pod. Would struts make a difference if the chutes are already directly attached? I just tried it again (with a probe this time!) using four parachutes, and that didn't work, either.

I think I basically need a drogue parachute. I guess I could add side structures like RocketPilot said, but it seems bizarre that that would be necessary...maybe there ought to be radial drogue chutes available.

[stupid_chris]

Could you post a screenshot? And was there anything else attached to the command pod? Also I guess I'll repeat what was said above, but were you using physical time warp? :l

[Klingon Admiral]

Well, I suspect that you would need more chutes, 2 radial chutes are enough to make a 3-man capsule coming in from the mun without proper aerobraking land safely. And then again, 2 small chutes on girders were no problem either for my small pod.

And no, In your case struts would not make sense, I at first thought you had a large capsule, put an ASAS on top and fitted the chutes there ... this routinely rips the ASAS of the capsule if nothing is done.

[regex]

First question: 4x physical time acceleration? It does horrible things to parachutes from time to time.

This right here. Parachutes open fully at a certain height (for instance, radials at 500m); figure that out for the chutes you are using and you will know when to stop time-accelerating and let the chutes open. Once they're open, you can time-accelerate the rest of the descent (although I recommend not accelerating your landing).

[Kimberly]

ASAS was on the bottom of the command pod, and a docking clamp was on the nose of the pod. Plus the parachutes, that was all.

I'm going to go ahead and blame time warp...I did use it during the descent. I'll go ahead and experiment without it and see if that makes a difference.

Edit: I tried it again with two radial parachutes. Due to forgetting to adjust the abort mechanism, only one parachute deployed. Yet without time warp, that single parachute was able to safely land the capsule. I guess time warp killed my kerbonaut, then...thanks for the help, everybody.

Edited June 26, 2013 by Kimberly

[Vanamonde]

A drogue will help you reach a lower speed before the main chutes fully open, lessening the shock of that sudden deceleration.

[Klingon Admiral]

A drogue will help you reach a lower speed before the main chutes fully open, lessening the shock of that sudden deceleration.

But considering that he is using 2 radials on a mk1 capsule, they alone should slow down the craft fast enough that a drogue won't be needed. Additionally, drogue, radials and a probe on a mk1 capsule will become very crowded.

[Vanamonde]

I find using 3 radials to be a little easier on the crew of a capsule, but actually, I was talking about the general utility of drogues.

[Rickenbacker]

ASAS was on the bottom of the command pod, and a docking clamp was on the nose of the pod. Plus the parachutes, that was all.

I'm going to go ahead and blame time warp...I did use it during the descent. I'll go ahead and experiment without it and see if that makes a difference.

Edit: I tried it again with two radial parachutes. Due to forgetting to adjust the abort mechanism, only one parachute deployed. Yet without time warp, that single parachute was able to safely land the capsule. I guess time warp killed my kerbonaut, then...thanks for the help, everybody.

There's your problem. If you physics warp, make sure to go back to 1x at 500m above the surface, otherwise you'll rip your parachutes off almost every time. Once the chutes are open you can warp again.