Jump to content

Newbie - MK16 parachute always destroyed by aerodynamic forces - Solved


paynterf
 Share

Recommended Posts

I'm a brand-new KSP player, and I have been beating my head against the problem of the MK16 parachute always getting 'destroyed by aerodynamic forces' on the way down, no matter what I did, just like many other newbies on this forum.  I have been doing the simplest possible configuration in the 'Contract's track - a command module, a 'Flea' solid-rocket booster, and a MK16 parachute.

However, I saw a post talking about 'monopropellant' on the command module, and reduced that to zero - that didn't help either, but it got me thinking, and I looked at the options for the 'Flea' solid booster.  Turns out that although you can't throttle a 'Flea' booster, you CAN reduce the starting fuel amount and the thrust available.  So, I reduced them both to about 1/2 scale, and now the rocket assembly tops out MUCH lower, and the parachute now works every time - YAY!!

https://drive.google.com/file/d/1Cz6jzboQKj0MRzksfV7pvL5-smfzZ45J/view?usp=sharing

I'm now experimenting with higher fuel loads to see if I can get the parachute to survive even with a full fuel load.  Woo Hoo!

 

Frank

 

 

Link to comment
Share on other sites

That chute may not be enough to bring the assembly down gently, but I don't recall experiencing chute destruction on something that small. Is the craft coming straight down on descent? If so, try ascending at more of an angle to come down at more of an angle. The result is reduced re-entry heating, and possibly less strain on the chute. 

Also, welcome to the forum. :) 

Link to comment
Share on other sites

Thanks for the quick response.  I'm sure that modifying the ascent trajectory would work as well.  However, from a newbie's perspective, it is very frustrating that all the tutorials show the basic configuration going straight up and straight down, with no trajectory modifications at all.  I was following the tutorial to the letter, but still getting 100% parachute failures - go figure.

The only clue that things might be different in the 'real' program is that the max altitude in the 'real' game is much higher than that shown in the tutorials, so I suspect Manley the other tutorial creators either modified the fuel loads and forgot to show that step, or were working with an earlier version with a smaller initial fuel load.

I've taught engineering and other skills for over 50 years, and this is a constant problem - tutorials that have hidden assumptions, and tutorial creators that never actually use their own products.  Hidden assumptions are very hard to uncover, because most experienced users no longer see them - they are just part of the background.  New users with no filters get tripped up, and the experienced users can't understand why it happens.

Frank

 

 

Link to comment
Share on other sites

The part I don't understand is that chutes shouldn't open if you're going too fast. When this happens to you how fast are you moving and how high are you? 

Link to comment
Share on other sites

On 5/13/2021 at 6:39 PM, Vanamonde said:

The part I don't understand is that chutes shouldn't open if you're going too fast. When this happens to you how fast are you moving and how high are you? 

Can't help you much, as I am a rank beginner. All I can tell you is I accepted all the defaults during construction of the simplest possible configuration, made sure the staging was correct, and launched. After that,  it didn't matter when I pressed the space bar to stage the parachute - it either never came out at all, or came out in drogue configuration and (either right away or eventually) ripped away.

The only way I was able to solve the problem was to figure out how to reduce the initial fuel load so the capsule didn't go as high, thus didn't develop as high a velocity before reaching the min pressure for the parachute.  It also didn't seem to matter what I set the min pressure too, either - just the initial fuel load (translating into max height after launch).

I have no problem with the physics, or the idea of flattening the trajectory to lower the max alt.  What I do have a problem with is a program that behaves badly right out of the box, with all default settings and the simplest possible configuration - that's just not right.

Frank

Link to comment
Share on other sites

On 5/13/2021 at 6:39 PM, Vanamonde said:

The part I don't understand is that chutes shouldn't open if you're going too fast. When this happens to you how fast are you moving and how high are you? 

I can imagine this scenario:

  • Going up with booster, high velocity
  • Booster exhausted.
  • Stage, parachute is armed
  • As craft gets higher, velocity drops - parachute deploys
  • Air thin enough that chute doesn't slow it down enough
  • On the way down enough velocity is gathered to destroy chute

Could it be something like that?

 

Link to comment
Share on other sites

On 5/13/2021 at 10:02 PM, paynterf said:

I was following the tutorial to the letter, but still getting 100% parachute failures

There are reports on the bug tracker, for this particular problem (link) and other problems with the training examples. 

KSP is now an old game, and I would guess new sales are diminishing, so we might not see them put the time into repairing the problems that have crept in.  But these KSP forums are quite helpful.

Link to comment
Share on other sites

Posted (edited)
9 hours ago, Kerbart said:

I can imagine this scenario:

  • Going up with booster, high velocity
  • Booster exhausted.
  • Stage, parachute is armed
  • As craft gets higher, velocity drops - parachute deploys
  • Air thin enough that chute doesn't slow it down enough
  • On the way down enough velocity is gathered to destroy chute

Could it be something like that?

 

I was thinking of something similar but in addition to the air being thin, it's the craft falling nose-first. The Mk1 does not have enough drag when falling nose-first to decelerate to parachute deploy velocity, regardless of whether it's coming in from atmospheric flight or orbit, and the reaction wheels are not strong enough to turn the pod around for proper deceleration if anything other than a heatshield is attached to the rear.

Pretty much the only thing that can be done in this case is to use the reaction wheels to produce drag by coming in as high an AoA as possible and sustain it for as long as the batteries allow, but even that isn't guaranteed to be enough.

Edited by Fraktal
Link to comment
Share on other sites

Posted (edited)

Hi @paynterf, welcome to KSP and the forums.

It's great  to see that you engineered a solution for your problem. KSP sure doesn't give the new player much in the way of detailed instruction for scenarios like these, which can certainly be frustrating.

You should understand that the ethos of the game's creator was one of "learn by failing." In other words, new players wouldn't be given an instruction manual to learn how to make rockets work, because that's not how any space program started. In real life, space programs learn how to make things work by flying tests and seeing what went wrong, making corrections, and then testing again.

Unfortunately, this can discourage new players that aren't already familiar with the fundamentals. Honestly, I want as many people as possible to enjoy this game that I love, but I also don't want to lose the experimental way of learning that it embodies. It's a tricky balancing act.

Edited by HvP
Link to comment
Share on other sites

It is certainly true that KSP is a game of learning by failing.

The trouble with the "Basic Construction"  tutorial mission, though, is that repeating it exactly in the game results in failure.  This kind of failure makes the player waste time going back to study details on the tutorial, and wonder if his installation of the game is broken.

I notice that the original poster did learn by failing,
found a solution that is possible with the limited first-launch parts in career mode, and
shared that solution, on his very first post, to the sub-forum for new users.

Link to comment
Share on other sites

  • 1 month later...

Hello. Noob here. Wish I had got on board this game years ago.

I experienced the same problem with 100% destroyed parachutes, when following Scott Manley's tutorial.  Looks like the current version of the Flea will lift that assembly waay too high, beyond the ability of the parachute to perform properly, unless you use the options to reduce the booster's performance, or maybe delay deploying the parachute until at a much lower altitude.  I'm guessing that Scott was using a much older version of KSP when he made the tutorials, back in 2016 or so, and the Flea's maximum performance then was considerably lower in that earlier version.

Edited by MissileMonkey
Link to comment
Share on other sites

The only way I can get the MK16 parachute to work at all is by reducing the flea's  fuel and available thrust to some low figure, thereby limiting the vehicle's ascent to about 5k meters or less.   I have yet to see the MK16 parachute survive a descent from any altitude above that.

None of the tutorials mention anything about the chute's minimum pressure and altitude settings, so I have to assume that the defaults should be used. (I have tried adjusting these to no avail.)  I've also experimented with chute staging timing, also to no avail.

This ain't right.

Edited by MissileMonkey
Link to comment
Share on other sites

On 5/13/2021 at 4:46 PM, paynterf said:

I'm a brand-new KSP player, and I have been beating my head against the problem of the MK16 parachute always getting 'destroyed by aerodynamic forces' on the way down, no matter what I did, just like many other newbies on this forum.

3 hours ago, MissileMonkey said:

The only way I can get the MK16 parachute to work at all is by reducing the flea's  fuel and available thrust to some low figure, thereby limiting the vehicle's ascent to about 5k meters or less.   I have yet to see the MK16 parachute survive a descent from any altitude above that.

  I'm... confused.  I've never run into this problem, at all.

(To be clear, I believe you, it's just that I'm trying to think what you may be doing that's different from what I'm doing).

I tried to reproduce this as follows:

  1. Build a ship consisting of Mk1 command pod, Flea, and a Mk16 parachute on top.
  2. All default settings, no tinkering whatsoever.  Didn't touch the parachute config, didn't touch the Flea settings, didn't even take monoprop out of the command pod.
  3. Launch to the pad, activate the Flea.
  4. Go straight up (this is basically the worst case scenario, if you're trying to stress the parachute).
  5. Flea burns itself out, the craft coasts up to a peak altitude of around 24 km.
  6. Activate the parachute at the peak of its trajectory.  (It doesn't actually deploy yet)
  7. Still keeping the same orientation (i.e. nose pointed at the sky), fall tail-first straight down.

Result:  The parachute deploys (without fully opening), as expected, when altitude has dropped far enough for the pressure to be usable.  Falling speed gradually creeps upward to a max of around 360ish m/s before it starts to decrease again.  Parachute opens fully when the craft is 1000 meters above ground level (the default) and falling at a bit over 200 m/s straight down.  Craft rapidly brakes to a descent speed of around 7-8 m/s and finishes the last couple of hundred meters peacefully.

In short:  I build a stock craft as described with all default settings, launch straight up, activate chute, let it fall straight down, it works just fine for me.

Is this different from what you're experiencing?  When your chute is destroyed, what is your altitude and how fast are you going?  When do you deploy your chute?

Link to comment
Share on other sites

  1. Build a ship consisting of Mk1 command pod, Flea, and a Mk16 parachute on top. Done.
  2. All default settings, no tinkering whatsoever.  Didn't touch the parachute config, didn't touch the Flea settings, didn't even take monoprop out of the command pod.  Done.
  3. Launch to the pad, activate the Flea. Done.
  4. Go straight up (this is basically the worst case scenario, if you're trying to stress the parachute). Done.
  5. Flea burns itself out, the craft coasts up to a peak altitude of around 24 km. Done. About 24.7 km.
  6. Activate the parachute at the peak of its trajectory.  (It doesn't actually deploy yet)  Done.
  7. Still keeping the same orientation (i.e. nose pointed at the sky), fall tail-first straight down. See below.

 

There was no mention in any of the tutorials about keeping the nose-up attitude. I was under the impression that the WASD keys wouldn't work once the engine quit firing, so I never tried to maintain any attitude.  This appears to be all that I was doing wrong. Perfect flights and landings now since I held the spacecraft's nose up.

Seems that they could save a lot of people a lot of grief by noting that this step is IMPORTANT!

THANK YOU!:vallove:

Link to comment
Share on other sites

1 hour ago, MissileMonkey said:

was under the impression that the WASD keys wouldn't work once the engine quit firing, so I never tried to maintain any attitude.

That engine doesn't actually have any gimbal, so your control on the way up isn't actually from the engine firing.

Your control authority comes from the insanely overpowered reaction wheels inside the command pod.  So with that pod (and most other pods) you will have some orientation control as long as you have EC (electricity).

In this situation, just turning on the SAS function (button on the top right of the navball, or toggle by pressing 'T') will put the ship into a mode that does what it can to keep pointing the same direction, so you wouldn't even need to try to keep orientation manually with WASD.

Link to comment
Share on other sites

14 hours ago, MissileMonkey said:

I was under the impression that the WASD keys wouldn't work once the engine quit firing

For a fun experiment, try launching a Mk1 command pod to the pad (just the command pod all by itself, no additional parts), and try playing around with WASD (also QE).  ;)

14 hours ago, MissileMonkey said:

Seems that they could save a lot of people a lot of grief by noting that this step is IMPORTANT!

Yeah, this is kind of a philosophical question when it comes to KSP.

On the one hand:  you're not wrong.  ;)  And what you're asking for, there, isn't necessarily an unreasonable thing to ask.

But, consider this somewhat analogous situation:  Suppose you were playing a racing game, and your friend tried getting into the car and flooring it down the race track, but never touched the steering wheel.  At the first curve, the car goes plowing off the track and smashes into some buildings and explodes.  Suppose that your friend got annoyed at this:  "Well, that's just not right!  Nobody told me that I have to actually touch the steering wheel to make it stay on the track, or that it would have problems if it smashes into buildings at high speed."  Your friend complains that the game is badly designed, and they should have had a tutorial explaining that you need to steer the car, that collisions are dangerous, etc.

You'd probably think that your friend is pretty silly there, right?  i.e. blaming the game, rather than using straightforward reasoning about the car?

Well... that's actually not all that different from the situation you found yourself in with KSP, if you think about it objectively.  But it sure feels different, doesn't it?  i.e. it feels like KSP is expecting too much from the player, but the racing game isn't?

If we think about why that is... personally, I think it's a matter of familiarity.  Everyone's been in a car, and has a basic idea of how cars drive and how steering wheels work, so even if the racing game doesn't explicitly tell you all the things you need to watch out for, it seems reasonable to expect the player to just intuitively "get" what they should or shouldn't do, at least in broad outline.

Whereas most of us haven't piloted a rocket ship, and the problems they encounter don't seem as intuitive... at least, not to some of us.  A lot depends on background and experience.

For example:  just to play devil's advocate for a moment:

  • You assumed that WASD wouldn't work... but nobody actually told you they wouldn't.
  • The game has lots of different things to try:   how about not going straight up?  how about not coming down nose-first?  how about tweaking the settings on the SRB?  KSP has a big "trial-and-error" ethic built into it; it's expected that you're going to try different things to find out what works and what doesn't, so it has a fair amount of license for lots of things not to work.  ;)
  • The game did, in fact, tell you that the parachute was destroyed because you're going too fast.  So the game had a certain expectation that you'd try doing things so as not to come down so quickly-- such as, for example, "don't fall like a dart".

Again:  Not saying that you were "wrong" at all.  After all, you have company; some other people have experienced the same frustration as you.  On the other hand... not everyone has-- some players actually do instinctively try those things and end up never encountering the problem.  Doesn't mean that they're any better or worse than you, just that they're approaching the game from a different viewpoint, is all.

 

I'll certainly grant your point that KSP can be dauntingly hard.  There are so many different factors to consider and counterbalance, many of which aren't intuitive to someone who isn't a physics major, and the game really doesn't do much to show you the ins and outs explicitly.  Yes, it has some tutorials... but they're kinda lightweight and don't go into a whole lot of detail.  That's understandably frustrating.  It is, however, also kinda understandable how it got that way.  Making really good tutorials for a game as complex as KSP takes a lot of development time and effort.  That doesn't mean it's not worthwhile... but the original KSP was developed on a relative shoestring, with a fairly small number of developers, and they didn't really have a lot of cycles to spare for tutorial development since they had their hands full just working on the main game.

The good news is, from what I've heard about KSP 2, they've heard this player "pain point" loud and clear, and they're putting a lot more work into having more detailed and useful tutorials.  We won't really know for sure how it stacks up until they release it, of course, but from the teasers they've shown us thus far, it sounds very encouraging.   My guess is that KSP 2 will deliver the sort of tutorials that you would have wished the original had.

 

Link to comment
Share on other sites

On 5/13/2021 at 3:46 PM, paynterf said:

I'm a brand-new KSP player, and I have been beating my head against the problem of the MK16 parachute always getting 'destroyed by aerodynamic forces' on the way down, no matter what I did, just like many other newbies on this forum.  I have been doing the simplest possible configuration in the 'Contract's track - a command module, a 'Flea' solid-rocket booster, and a MK16 parachute.

Out of curiosity, what is your air speed when you are deploying the chute? I'm going off memory here, so please forgive me - Normally, for the Mk 16 chute, wait until you are between 15,000 meters and 10,000 meters to deploy. As you reenter Kerbin's gelatinous atmosphere, you will go from having a ring of plasma around your capsule to having an effect that simulates traveling faster than the speed of sound. By the time you get to the speed of sound, and depending on your angle, your altitude should be between 23,000 meters and 18,000 meters. By the low end of that, your capsule speed will, because of atmospheric pressures, begin to drop a little before you deploy your chutes.

Once you get to an air speed of no higher than 420 m/s, you can safely deploy chutes. If you have a radial mount drogue chute, you can deploy that at around 600 m/s and allow it to bring you down to around 350 m/s before deploying your main chute (the Mk 16).

As a side note, and in my experience, the Mk 16 doesn't fully deploy until your altitude is between 1,000 and 500 meters. You'll know it because your air speed will drop to around 12 m/s.

I hope that helps some.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...