Quantcast

Harness Setup Question

The Rocketry Forum

Help Support The Rocketry Forum:

Lowpuller

Well-Known Member
Joined
Nov 23, 2013
Messages
2,230
Reaction score
11
Please share details of how you attach you parachute and fire blanket to your harness.

I'm very interested in the relationship between the fire blanket connection and the parachute connection.

I presently use a butterfly knot to create a loop for the quick link.

I then slide on the fire blanket and attached it to the quick link with some very heavy thread.

I then attached the parachute and use an o-ring to keep the lines together and properly orientated on the link.




What I would like to do is increase the distance between the fire blanket connection and parachute connection. I want to do this to insure clean air for the parachute opening, force the canopy out of the fire blanket burrito, but I am concerned this may create another potential for a malfunction.


If my canopy were large enough, I would attached the blanket to the apex of the canopy, similar to a skydiving DBag, but that won't work in this scenario as the canopy and fire blanket are too close in size..


Pictures please, pictures please, maybe even Teddy might weigh in (PLEASE) even though this is a homemade harness.

My harness is routed incorrectly through the fire blanket in these pics, please see the pics below...

ImageUploadedByRocketry Forum1480874745.277530.jpg


ImageUploadedByRocketry Forum1480874769.402372.jpg


ImageUploadedByRocketry Forum1480874820.285287.jpg
 
Last edited:

Lowpuller

Well-Known Member
Joined
Nov 23, 2013
Messages
2,230
Reaction score
11
Here are some pics of my current drogue setup with the proper harness routing.

ImageUploadedByRocketry Forum1480875670.428242.jpg

ImageUploadedByRocketry Forum1480875685.746661.jpg

ImageUploadedByRocketry Forum1480875703.736764.jpg

ImageUploadedByRocketry Forum1480875717.790930.jpg
 

rharshberger

Well-Known Member
Joined
Oct 13, 2014
Messages
9,710
Reaction score
1,694
Location
Pasco, WA
The only thing I do different than you is I have a short tubular kevlar riser (?) about 12-18" long between the chute and the quick link holding the nomex, that way the nomex doesn't get tangled into the shroud lines. I believe this is similar to what you are wanting to do to get a bit of clearance/clean air for the chute, it has worked for me many times (most of my recovery failures have been getting the laundry out in the air not getting it open once there).
 
Last edited:

Nytrunner

Pop lugs, not drugs
Joined
Oct 15, 2016
Messages
7,221
Reaction score
2,702
Location
Huntsville AL
The way I did the harness for my old school's IREC team was to attach the parachute 1/3rd of the shock cord length away from the lighter piece of the rocket.
Then tied the Nomex square (12x12 for a 4" airframe) between the parachute and the charge end of the cord. Either 2' from the charge or, for the main in the payload tube, 6" past the end of the tube (which was riveted to the av-bay with the charge).
 

Onebadhawk

Sponsor
TRF Sponsor
Joined
Jan 11, 2013
Messages
6,064
Reaction score
366
First,,
I agree completely with your sentiment...
We've all seen the the harness slipped through the hole on the blanket
and the blanket rides up the harness and fouls the chute...
I also believe this happens more often on larger rockets with larger blankets...
I recommend all the time, especially on a larger rockets harness set up,,
let me fix the blanket to the harness for just this reason..
On the booster your dealing with much shorter shroud lines on the chute..
I like to keep the drogue as close as possible to the av bay but still leave ample room for the drogue
to be forced down into the booster when the charge goes off without hindering separation...
For sure the rocket will fall nicer from apogee this way,, more controlled ,, less flailing around,,
a much greater chance of the payload section pointed out into open air when it fires,,
as opposed to pointed straight down and firing directly into the path of the falling payload section..
Because of the shorter shroud lines I like to keep a bit of extra distance between the drogue and it's blanket..
With all this said,, just for arguments sake,, I'll put the drogues 3rd loop at about 3 ft and I'll fix the
drogues blanket just a bit over 4 ft at a 45 degree angle pointed up toward the drogue..........

The payload section is always much less critical,, many different configs will work just fine...

Sizing the drogue is what's most important...
If the rocket is falling from apogee and it's flailing around uncontrolled the drogue is too small...
If the rocket is falling and the 2 sections are both pointed straight down the drogue is too large,, ( this is much more common )...

Teddy
 

Handeman

Well-Known Member
TRF Supporter
Joined
Jan 18, 2009
Messages
7,736
Reaction score
336
Location
Stafford, VA
First, I stopped using quick links a while back. I have a parachute for each rocket so I just put a loop of shock cord through the loop on the chute and run the chute through the shock cord loop and pull tight. I do this with mains and drogues. The only one I don't use this with is my L3 bird because the chute has D-Rings on the ends of it's shrouds and they are attached to the very end of the shock cord via quick link.

attach chute to shock cord.png

I use a piece of Kevlar line tied in a loop, solid copper wire, or whatever I have handy to tie the chute protector to the shock cord below the chute. The protector can than slide down the cord after the chute comes out.
 

ksaves2

Lifetime Supporter
TRF Lifetime Supporter
Joined
Nov 25, 2009
Messages
5,984
Reaction score
294
What I do is with some of the heavy, stiff Nomex protectors is I'll secure it closer to the sustainer end so when the chute is blown out of the rocket, as the harness extends the chute is pulled out. It doesn't need protection from heat anymore. There is a little slack line between the chute quick link and the protector. Actually, I use a piece of duct tape to hold the protector to the line but one could do a restraining loop. Having to rely on the protector
to "fall away" is unreliable.

If one secures a stiff protector to the quick link like shown above, it could foul the chute. Especially if it's in a smaller rocket. I have one of those hexagonal protectors and they are quite floppy. I've secured them as shown without trouble.
Some of the stiffer protectors could stay curled around the chute and impede it getting free. I use this strategy with the Jolly Logic Chute Release. I haven't had a failure since I get the restrained chute package out of the protector after deployment. Follow this advice and a person will have more reliable deployments. Kurt
 

Lowpuller

Well-Known Member
Joined
Nov 23, 2013
Messages
2,230
Reaction score
11
To be more specific, I'm looking for help determining the dimensions for A - G. I'm hoping someone, possibly Teddy, can share some recommendations.

ImageUploadedByRocketry Forum1480903897.974824.jpg

ImageUploadedByRocketry Forum1480903912.067015.jpg

ImageUploadedByRocketry Forum1480903925.902519.jpg

Thank you for any help,
 

Coop

Well-Known Member
Joined
Dec 15, 2011
Messages
1,768
Reaction score
3
Dimensions there, I would say, are dependant upon what you're using as a main, drogue, rocket weight (harness strength/weight), and overall size/scope of the project.

I'd say main at 1/3 from nose, if not using a deployment bag. If using a bag and pilot... pilot to recover nose at close to same rate as rest of rocket so they land close, then you can use a much shorter main harness.

For the apogee event... Typically, I'll put whatever size streamer I'm using, plus a few feet --so, 12' streamer around 15' from av-bay, and this means around 30' from booster. 15' streamer will be closer to 20' from av-bay and 40 from booster... then again, I tend to think of streamers at apogee, because... well... that's generally how I fly anymore. If I had to use a chute at apogee, I'd see how long it is from apex to attachment point, add a foot or two of clearance, then have the shock cord as long as I felt like using. Fire blanket would be attached to cord... above the streamer with a few inches separating (fire blanket is never going to foul a decent-size streamer, dig), below a parachute (just flipped inside so it's oriented to face the ejection charge from the av-bay). Swivel... this would be in my range box.


Later!

--Coop
 

Onebadhawk

Sponsor
TRF Sponsor
Joined
Jan 11, 2013
Messages
6,064
Reaction score
366
First the payload section because it's extremely simple..
Use a 2 loop harness and attach the main directly to the nose cone...
The placement of the blanket is less critical because the mains shroud lines will generally be long enough
to keep the canopy far enough away from the blanket to foul..
You'd be fine with the blanket fixed at 3 or 4 ft under the nosecone and the main connected directly to the nosecone..

The booster..
The 3rd loop for the drogue...
The rocket will fall in a nice controlled inverted "V" formation with the drogue closest to the av bay..
But the drogue must be far enough from the av bay to allow the av bay / payload section to move away
when the separation charge goes off and the drogue is forced down into the booster...
This is why I am constantly asking for the measurement from the top centering ring to the top edge of the booster...
Put the drogue a bit further down then that measurement,, if it's 30" put the 3rd loop at 4 ft....
Now we know where the drogue is I'll fix the blanket to the harness at 5 or 6 ft pointed at the drogue..
You can easily pack and load everything, but in flight the blanket won't be able to reach the drogue to foul it..

The swivel...
I find that if you have a booster that spins while falling from apogee the only way to stop the harness from spinning up
is to put the swivel as close as possible to the booster with a heavier harness piece below the swivel then the boosters harness is..
This seems to make the lower part of the swivel have more of a tendency to stay put / steady so the top half can spin...

Hope this helps...

Teddy
 

Onebadhawk

Sponsor
TRF Sponsor
Joined
Jan 11, 2013
Messages
6,064
Reaction score
366
Tim C. had a nice pic of a swivel attachment that really illustrates the swivel point...
I'll email him this thread,, maybe he'll chime in and post that pic...

Teddy
 

timbucktoo

Well-Known Member
Staff member
TRF Supporter
Global Mod
Joined
Jun 13, 2014
Messages
7,764
Reaction score
1,137
Location
Cocoa Beach
Tim C. had a nice pic of a swivel attachment that really illustrates the swivel point...
I'll email him this thread,, maybe he'll chime in and post that pic...

Teddy
Teddy - are you referring to these pics? And I don't mean to give you a plug but both of these rockets are flying with a 3rd loop kevlar harness manufactured by OBH :)

IMG_0206 (2).jpg

SIT_2698 (2).jpg
 

Lowpuller

Well-Known Member
Joined
Nov 23, 2013
Messages
2,230
Reaction score
11
Teddy,

Thank you, this is very helpful, and very much appreciated especially considering you manufacture the One Bad Hawk harnesses, you are clearly an expert in this subject.

I'm not sure I fully understand your concern with the length of harness between the AV Bay and the drogue.

Is the concern that you may not get separation, if the drogue is pushed one way, and the AV Bay is pushed the other, and the harness is to short to allow the AV Bay to leave the booster?


I have heard some folks indicate they were concerned with this, so they use very long ematches so the booster section charge can be located in the bottom of the booster section and act just like a motor ejection charge.

My only other Dual Deploy rocket used motor ejection as the back up, so frankly I don't know if this has ever been a problem in my current DD because the backup charge would have corrected the problem.

Other folks say it is all about the pressure and direction of the ejection charge does not matter.

I believe, if I am interpreting your concerns correctly, your dead on the money. It is about direction , pressure AND harness length.

Great info, thank you again...

And Tim, thank you as well, I remember seeing those pics and the associated swivel location discussion, based on these pics I added a swivel, maybe prematurely.
 
Last edited:

Onebadhawk

Sponsor
TRF Sponsor
Joined
Jan 11, 2013
Messages
6,064
Reaction score
366
No Tim,, that's not the swivel pic,, you had a close up of a swivel that the bottom of the swivel was in a heavy red Nylon harness..
Far heavier then the booster's harness above the swivel.. So the bottom of the swivel would be more likely to spin with the booster and let the top half hold still..

Low, you certainly have the correct thought line..
We all come up flying low power,, where the charge is below everything that must be pushed out of the tube,,
same as the payload section in our HP flights now...
But the apogee charge in a HP rocket is opposite,, instead of forcing everything out of the tube,, it shoves everything down into the tube..
If the drogue were attached directly to the av bay at the moment the charge went off the drogue and blanket package would be shoved down into the tube at the same time as the av bay were trying to move away,, that is how an incorrect set up will hinder separation....

Just move the drogue down the boosters harness a few ft,, just a bit more then the distance from the top centering ring to the top edge of the booster..
The the drogue package can be freely shoved down into the tube,,,, now at this moment on the bottom of the boosters harness you have a booster with an empty motor case and the fins,, no mass and all of the drag... But at the top of the boosters harness you have the av bay / payload section,, all of the rockets weight at this point in the flight with none of the drag ( no fins ).. The payload section and booster will naturally want to separate ,, the payload section will easily drag the drogue package out of the booster.........

Teddy
 

Lowpuller

Well-Known Member
Joined
Nov 23, 2013
Messages
2,230
Reaction score
11
Tim,

Thanks for sharing the pic.

I love to see the larks head knot get used this way. However, if this were a skydiving rig, I would hand tack the larks head with two loops of very heavy thread(Super Tack). Probably not needed but supper easy insurance.

I'll post a pic of my setup soon, however I know in advance your gonna fuss at me for my swivel location. I came about 12" out of the booster instead of 2".

Teddy, thank you again for the help, I hope to meet you on a range sometime.
 

Onebadhawk

Sponsor
TRF Sponsor
Joined
Jan 11, 2013
Messages
6,064
Reaction score
366
Yep,,, that's the pic Tim,, thank you for digging that up,,that aught to work well...

Low, 2" or 12" is not a big deal..
As long as you get the point...
If you could have a steel bar welded to the eye on the top centering ring
reaching up to almost where the av bay sits,, and weld the bottom of the swivel to that bar,,
then the top of the swivel would surely be free with the harness...
It really is difficult to explain...

I'd love to fly with you Low
but I'd wouldn't know if I was,, lol...

Teddy
 

Lowpuller

Well-Known Member
Joined
Nov 23, 2013
Messages
2,230
Reaction score
11
I'm the guy with that really big, cool looking rocket that just made an awesome flight, accompanied by my wife, who is really hot, and I ain't talking about from the sun!

Ok I embellished on the first part of the statement, but the second part is dead on........don't know how or why but I'm a lucky or rather blessed guy.

......
 

rharshberger

Well-Known Member
Joined
Oct 13, 2014
Messages
9,710
Reaction score
1,694
Location
Pasco, WA
I'm the guy with that really big, cool looking rocket that just made an awesome flight, accompanied by my wife, who is really hot, and I ain't talking about from the sun!

Ok I embellished on the first part of the statement, but the second part is dead on........don't know how or why but I'm a lucky or rather blessed guy.

......
....maybe she has a really good life insurance policy since your other hobby iirc is parachuting. 😃
 

Onebadhawk

Sponsor
TRF Sponsor
Joined
Jan 11, 2013
Messages
6,064
Reaction score
366
hahahahahahahaha...
That's too funny Rich.....
Hey,, I'm with ya Low,,,
my wife is really hot too, but she's a little crazy,, lol...

Teddy
 

Lowpuller

Well-Known Member
Joined
Nov 23, 2013
Messages
2,230
Reaction score
11
My wife don't like rockets so much, but she has been seen jumping out of few hundred airplanes!!!
 

Lowpuller

Well-Known Member
Joined
Nov 23, 2013
Messages
2,230
Reaction score
11
So here is what I would up with......

Overall shot, hopefully I got this right.........
ImageUploadedByRocketry Forum1480997227.891688.jpg

Main attachment to nose cone, note finger trap attachment of harness to nose cone and tacked silicone guide, skydiver style to insure lines stay in place and load link properly
ImageUploadedByRocketry Forum1480997251.959412.jpg

Main blanket tacked to a butterfly knot, butterfly knots are great for a lateral attachment
ImageUploadedByRocketry Forum1480997270.538623.jpg

Main blanket back side showing butterfly knot
ImageUploadedByRocketry Forum1480997290.486558.jpg

Payload AV Bay attachment via finger trap
ImageUploadedByRocketry Forum1480997311.843648.jpg

Booster AV Bay attachment via finger trap
ImageUploadedByRocketry Forum1480997331.266317.jpg

Drogue attachment with quick link and tacked silicone guide
ImageUploadedByRocketry Forum1480997356.451404.jpg

Drogue blanket tacked to a butterfly knot
ImageUploadedByRocketry Forum1480997377.493921.jpg

Swivel attachment using two finger traps
ImageUploadedByRocketry Forum1480997428.519513.jpg
 

Attachments

Lowpuller

Well-Known Member
Joined
Nov 23, 2013
Messages
2,230
Reaction score
11
Harness motor mount attachment via finger trap, this was completed prior to gluing the motor mount in place.

ImageUploadedByRocketry Forum1480998108.937840.jpg
 

Lowpuller

Well-Known Member
Joined
Nov 23, 2013
Messages
2,230
Reaction score
11
What happened? I posted a few pics and all my help disappeared.
 

Onebadhawk

Sponsor
TRF Sponsor
Joined
Jan 11, 2013
Messages
6,064
Reaction score
366
hahahaha,,
We thought you were done...

Teddy
 

Lowpuller

Well-Known Member
Joined
Nov 23, 2013
Messages
2,230
Reaction score
11
What do you think about the silicone tubing?
 

timbucktoo

Well-Known Member
Staff member
TRF Supporter
Global Mod
Joined
Jun 13, 2014
Messages
7,764
Reaction score
1,137
Location
Cocoa Beach
What's to keep it from sliding up your shroud lines?
 

mccordmw

Well-Known Member
Joined
Jan 18, 2016
Messages
1,020
Reaction score
47
Location
St. Louis, MO
So here is what I would up with......

Overall shot, hopefully I got this right.........
I always use much longer harness length between the booster and the payload bay. The length between payload bay and nose cone can be much shorter. I think of it in terms of how much deceleration I'm possibly going to see. Sure, the rocket will be near apogee on drogue deployment, so it won't be falling fast, but that's only on a perfectly straight up and down flight. A tiny bit of horizontal movement will quickly mean your deployment speed is quite fast.

To alleviate the shock, I use a longer line to allow for less snap when the drogue opens.

On drogue, you're likely falling around 18-25 m/s. When the main deploys, that's not as much possible snap as when the drogue deploys. That means you don't need as much harness to absorb that shock.

I've been going with a general length of:
Booster to payload (drogue deploy) = 2-3x total body length
Payload to nose cone (main deploy) = 1x total body length

People have all sorts of preferences though.
 

Lowpuller

Well-Known Member
Joined
Nov 23, 2013
Messages
2,230
Reaction score
11
timbucktoo

It is tacked in place with heavy thread. Thousands of jumps on my skydiving rig like this with no issues.
 

Lowpuller

Well-Known Member
Joined
Nov 23, 2013
Messages
2,230
Reaction score
11
mccordmw

Look at my overall picture and how the harness zigzags. My lengths are much longer than what you described.

I'm at least 4 body lengths on each section.
 

Latest posts

Top