How to loose speed in lower atmosphere in early career ?

[Rucki]

Actually Im at a normal career ( but without quicksafe ) and have all the 90-Science Parts researched.

My problem is that if do missions like " bring 4 tourists to mun orbit and back " that my Upper ( reentry ) Stage is just too heavy for reentry on kerbin.
Normally I will get to an 55 AP and 55 PE Orbit, before i drop my last engine and let the heatshild do the rest. With enough SAS its not a problem like it was in early career stages, I think i even do not need the Heatshild but...
 

Under 2000-3000m my speed is anyway too high to open the parachute. I havent got already the MK12-R Chute or Airbrakes so I cant use them. 
If I steer my landing stage in about 3000m vertically to retrograde i will get enough drag to go under 280ms and can open the parachute, but thats a very risky thing.

Do you have some hints how to get more drag in lower atmosphere at that early career stage ?

 

Ps: Maybe i should limit the weight of the tourists, i think 80kg should be the max allowed weight, so "No McDonalds before flying to the Mun, or you will have a bad time at reentry" hehe

Edited January 7, 2016 by Rucki

[sal_vager]

There's a few things you can do.

First, try jettisoning the heatshield, you will need to add a decoupler for this, heatshields are pretty heavy so they have a lot of inertia to overcome.

Wait till the flames go out though.

 

Another trick I use is to add a structural girder to the top of my parachute (surface attach), then another chute on top of that, during launch the top chute acts like a nosecone to reduce drag, but when re-entering the bottom of the girder is pretty draggy, so helps slow you down.

[Plusck]

I've never, ever had a problem getting under safe opening speeds for parachutes in stock 1.0.5 (medium difficulty setting), except in the very early career (I lost Jeb...) with suborbital flights. I have opened parachutes in a mountain valley once or twice, at under the height of the alarmingly-close peaks, but that's it. Maybe I'm just not making my ships long and skinny enough.

For Mun or Minmus I tend to set Pe to about 30km, and generally take off 50-75% of ablator in the VAB (though I often forget). I've never used drogue chutes or airbrakes for in-system reentry, only for interplanetary missions.

So I'm finding it hard to visualise how it's possible for this probkem to arise. I've also stacked two Mk1 pods to take tourists around, and that worked fine too, although I can imagine that more than that could be a problem.

As for suggestions... you could try;

- reducing the ablator load in VAB

- using landing legs as airbrakes. If your tourists need to land on the Mun, this would mean re-entering upside down, so you'd put a heatshield on top of your lander and deploy landing gear at about 10km on the way back.

- not stacking more than two pods, or using an oversized heatshield if you do

- getting rid of monopropellant if you don't absolutely need it (which you shouldn't at this stage in career if you're not docking)

- finding the perfect re-entry Pe. Basically you want to ensure that you're low enough to have a nice long arc in the 10-14km zone, but high enough to ensure you don't get there too quickly and explosively. 29-32km directly from the Mun or Minmus works really well for me.

edit: actually on rereading your OP, I don't quite understand the 55 AP and 55 PE orbit and dropping of engines. You really don't need to use engines to brake for re-entry from the Mun or Minmus. It can actually be counter-productive since your high orbital velocity on arriving at a Pe of around 30km means that you spend quite a long time there before slowly dropping. If you try to brake too much, your angle as you hit the dense lower atmosphere will be higher and you'll spend too short a time there before lithobraking.

Edited January 7, 2016 by Plusck

[Mister Dilsby]

If you have some fuel and an engine remaining on your upper stage, you can use thrust to decelerate. I quite often land heavy ships with no heatshield at all by firing the engines to reduce velocity in the upper/middle atmosphere. 

[Randazzo]

If you come in dead-stick retrograde, velocity will be harder to lose. Pitch the heatshield end up or down a few degrees (not TOO much) and your drag will increase noticeably. Once the flames die out you can yaw and pitch as hard as you can and it will slow you down even more.

[Rocket In My Pocket]

I hate to be "that guy" but...

I'm gonna be! 

Lol.

Spoiler

lose

lo͞oz/

verb

1.

be deprived of or cease to have or retain (something).

"I've lost my appetite"

synonyms:be deprived of, suffer the loss of; 

no longer have

"he's lost a lot of blood"

2.

become unable to find (something or someone).

"I've lost the car keys"

synonyms:mislay, misplace, be unable to find, lose track of, leave (behind), fail to keep/retain, fail to keep sight of

"I've lost my watch"

1.  

Spoiler

loose

lo͞os/

adjective

1.

not firmly or tightly fixed in place; detached or able to be detached.

"a loose tooth"

synonyms:not fixed in place, not secure, unsecured, unattached; More

2.

(of a garment) not fitting tightly or closely.

"she slipped into a loose T-shirt and shorts"

synonyms:baggy, generously cut, slack, roomy; More

verb

1.

set free; release.

"the hounds have been loosed"

synonyms:free, set free, unloose, turn loose, set loose, let loose, let go, release;More

 

Edited January 7, 2016 by Rocket In My Pocket

[Death Engineering]

Depending on the CoM/control authority, you may also find adjusting the flight profile from around 10km will take advantage of lifting body effect to level out a little. I just did two tests where I just "left it" and the other where I had aggressively tried to pitch-up and was able to open the chutes over 2km higher that way.

Same re-entry quickloaded at 10km and pic capped as soon as the chute warning went from 'yellow' to 'grey'.  It was 4.4Km higher when I could safely open chutes.

Doing nothing:

http://i.imgur.com/snYLU9Yl.png

Trying hard

http://i.imgur.com/5YF66Ucl.png

Edited January 7, 2016 by Death Engineering
added pix

[Streetwind]

Try a more confident reentry profile. Leave your AP out at 200km, put your PE down at 25 or even 20 km. Sounds counterintuitive, but it's a safer, gentler trajectory than the timid sticking-your-toe-in thing that you're currently doing.

While usually this is a solution to "I am burning up", and that is not your problem per se, it should still result in your craft automatically entering a period of almost level flight deep down in the atmosphere. This gives you plenty of time to bleed off horizontal velocity, and puts a hard limit on how much vertical velocity your craft can have when approaching the ground.

Edited January 7, 2016 by Streetwind

[Gojira1000]

Oddly enough, I think you may be coming in too slow if you've slowed to a 50 or 55 PE orbit. Then you'd wind up dropping too steeply when you did another burn. Come in from about 75 and do one burn to drop your PE to 20 or 30 KM. I was landing double MkIs and a Science junior (and once a triple Mk1 on a suborbital death-tour, which was interesting) in early career.

[Jhawk1099]

So I am pretty much new to this game but I have had many successful round trips from minmus and a few from the mun. I usually only take the mk1 capsule, mk16 parachute, and the 1.25 meter heat shield back though. This works almost every time if you keep a nice mostly horizontal re-entry trajectory. But since you have to bring back more than that you wont slow down as fast. I would suggest areobraking. This is where you keep your periaps at the upper limits of the atmosphere but your apoapis out of the atmosphere. This will slow you down a bit but will keep you in orbit. Several orbits later you will slow down to the point where your apoapis is inside the atmosphere. At this point you will be going slower than you would have before without the areobraking orbits. Eventually you will fall back to kerbin. This will take much longer but should be safer. This is used a lot when landing on duna so look up some videos on landing on duna and it will help you with this. But this has some problems in that it needs more electricity because it takes longer and tourists have no ability to control things so if you are using a drone core you will want some solar panels. I think this will work but maybe not.

 

 

 

[Fearless Son]

13 minutes ago, Jhawk1099 said:

But this has some problems in that it needs more electricity because it takes longer and tourists have no ability to control things so if you are using a drone core you will want some solar panels. I think this will work but maybe not.

It will work, I land back on Kerbin this way all the time as a fuel-saving measure.  Saving a little in the tank also gives me the option of making last minute burns to adjust my approach.  But I wanted to add a note on the electricity thing: flat solar panels tend to do poorly under direct atmospheric heating, so if you are using those make sure they are in the lee of the craft as it flies through the upper atmosphere.  If you are using deployable solar panels instead, make sure they are the kind with casings so you can stow them.  The casings can take a lot more heat, but the deployed panels are extremely delicate and can get ripped off the ship by atmospheric friction.  Hence they need to be stowed when the ship is making its atmospheric transition, but extended while outside of it to restore electricity.  

Involved and a little boring, but certainly safe.  

[SSgt Baloo]

2 hours ago, Streetwind said:

Try a more confident reentry profile. Leave your AP out at 200km, put your PE down at 25 or even 20 km. Sounds counterintuitive, but it's a safer, gentler trajectory than the timid sticking-your-toe-in thing that you're currently doing.

While usually this is a solution to "I am burning up", and that is not your problem per se, it should still result in your craft automatically entering a period of almost level flight deep down in the atmosphere. This gives you plenty of time to bleed off horizontal velocity, and puts a hard limit on how much vertical velocity your craft can have when approaching the ground.

Best reentry advice I've gotten so far. Just tried it and it works, although there were a few nail-biting moments.

 

[Snark]

I'm with @Death Engineering.  Body lift is your friend.

In early career tourist missions, I like to use the Mk1 crew cabin a lot-- it's really light, which makes it good for sending up to orbit and good for reentry.  In particular, since it's big and cylindrical, it generates lots of body lift.

So a typical 4-tourist reentry vehicle will have a Mk1 command pod with a couple of Mk1 crew cabins under it, and then some AV-R8 winglets on the back end to make it steerable.  When going through the "hot" part of reentry, I do it spaceplane-style (i.e. nose-up at about 30 degrees)-- it's a bit nail-biting but doable without a heatshield, as long as I'm just reentering from LKO and not the Mun or something.  (If I need better heat resistance, then I put a heatshield on the front of the craft, with a disposable nosecone to facilitate launch.)

Once I get down out of the charbroil zone, I just steer to keep the nose up.  The craft slows down a lot... I can actually fly down to under 10 km, turn, and climb a couple of km if I want to!  By the time I get anywhere near the ground, I'm going a lot under 200 m/s and the parachutes have no problems at all.

The steerability also makes it easier to come down close to KSC, if I'm so inclined (I usually don't bother, the few extra recovered funds aren't worth the effort, but sometimes try for it just for fun).

[Rucki]

Thank you all, you all have genius ideas how to slow down. In fact tried to come down with higher AP about 200km and pitching up for about 5 to 10 degrees, with the help from MJ-Readouts for pure drag (only this Im not using the
Autopilot )
I made a safe descent with Mk1 pod and 2 crew cabins + science moduls and it went well

Well, sorry for my bad english, when i went to school I could speak better I think, but i lived the last 3 years in poland, mainly to learn polish ( Im a german native speaker ) and since that i forgot too much words and grammatical things about english, it looks like in my head is not enough space for 3 languages hehe.

[Gojira1000]

Your English is great, no worries Rucki. Just glad you got to the ground in one piece!

[PTNLemay]

10 hours ago, Plusck said:

I've also stacked two Mk1 pods to take tourists around, and that worked fine too, although I can imagine that more than that could be a problem.

I can attest to that.  I tried to build a 4-seater once (using stacked 1-seat pods), and it was just a lawn-dart.  I was regularly hitting 300 m/s upon hitting the ground, even while trying desperately to pull up out of the dive.

Edited January 8, 2016 by PTNLemay

[rakutenshi]

It sounds like you're just building the payload/crew section too skinny for its mass. It may be worth adding some control surfaces to the portion of the ship that will be reentering, this will aid in 2 ways.

1.) More drag just by being there,  as long as your center of mass is ahead of your center of lift/pressure these can also be used as passive stabilizers  for reentry. (if you're coming in bottom first, you'll want to make sure the mass is below the center of lift when you're putting your payload together)

2.) Improved manouvering in atmosphere without relying on ASAS will allow you to bleed off more speed once the reentry has cooled off enough that you feel safe turning. Even pitching up 5-10 degrees can significantly increase the amount of drag your ship is feeling and drastically slow it down.

[Shark4558]

You can try a retro- flea SRB.naturally the SRB would put the nose of the craft down, and the SRB when you use it,it slow downs the craft a lot ... so i mounted the srb on my sub orbital hop ship, which never arrived at a safe speed,it became paper on the floor, but the srb let the ship be usable...

that was my idea...i hope it is useful