Why add a 3rd Loop to a harness?
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My Madcow Arcas coming down on it's drogue.
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First,,
The position of the 3rd loop..
The echarge is on the bottom of the av bay..
The expanding ball of gas from the e charge is going to shove the drogue down into the booster..
If you were to attach the drogue to the bottom of the av bay it would hinder separation..
The drogue couldn't move down into the booster tube AND the top half of the rocket move away at the same time if they are attached to each other..
If you attach the drogue down the boosters harness so it's a bit further down the harness then the distance from the top centering ring to the top edge of the booster the drogue will be free to be shoved down into the booster at the moment the echarge goes off without holding the payload section / av bay from moving away.. Then separation will freely occur with nothing holding the two halves of the rocket together.. At this moment the motor tube is empty,, in the bottom half of the rocket you have the drag of the fins and an empty motor tube,, all of the drag and none of the weight..
At this same moment in the top half you have all of the electronics and batteries and all of the recovery gear,, and the nosecone,, in this top half you have all of the weight and none of the drag...
These two halves will naturally,, try,, have a tendency to separate,, move away from each other..
The top half will drag the drogue out of the booster effortlessly...
The size of the drogue..
Without a drogue the rockets to sections flail around uncontrolled until the main fires..
There is no control over where the nose cone is pointed when the main fires..
If it is pointed down then the main is being fired into the path of the falling booster and harness..
This makes for the greatest risk of entanglement..
With a drogue the 2 sections should make an inverted “V”
with the drogue the top point as they fall from apogee..
With too big of a drogue the legs of the “V” are both hanging straight down..
This guarantees the main will be fired somewhere below where the payload section is..
This increases the chances of entanglement..
With a very small drogue the 2 legs of the “V” are spread wide..
This will make the nose cone point away from the booster and it's harness
while the rocket is falling from apogee..
This give by far the greatest likelihood that the nose cone will be pointed away from the rest of the rocket when the main fires.. And the least chance of entanglement..
In the payload section (the top half of the rocket, over the avionics bay),
the main parachute is attached directly to the hard point in the nose cone,
since it's pushed upwards, from underneath it.
Eliminating the necessity for the 3rd loop in the main chutes harness.
For this reason I use a 2 loop harness on top in the payload section...
I always use a longer harness in the booster then in the payload section..
The length is necessary in the booster because if the two separate parts at the apogee event are still moving away from each other quickly when they reach the end of a short harness the nose cone may pop off and you'll have a main deployment at apogee..
I like altitude ( as opposed to velocity )..
Because of this I like a fast as possible decent on drogue.
This is why I put the 3rd loop as close as I can to the av bay. Putting the 3rd loop as close to the av bay / payload section as possible gives the drogue leverage against the mass of the av bay / payload section..
So you can use the smallest drogue possible but still control the payload section.
With no drogue the payload section flails around uncontrolled during the decent from apogee..
Where it’s pointed when it fires is a hope and a prayer.
A small drogue holds it still, pointed out and away from the booster.
They will make the shape of an inverted “V” when falling..
The larger the drogue the narrower the legs of the “V” until you get to WAY too big or a drogue and both the booster and the payload section are hanging straight down from the oversize drogue.
Now the payload section is being held in place pointed straight down so it will fire the nose cone directly into the path of everything else falling.
Highly increasing the risk of entanglement.
Those that are proponents of flying drogue less have only used way too big of a drogue..
Please carefully check out these pics of a flight of “SteamPunk”’s..
http://onebadhawk.com/mars-8222015.html
The best jived out rocket I’ve ever seen is my 4” scratch “SteamPunk”.
It’s a big, heavy 4”, anywhere from 30 to 50 lbs on the pad according to what motor is in it..
The perfect drogue is 16”..
If it’s a particularly gusty day I’ll go a bit larger to a 20”..
The position of the 3rd loop..
The echarge is on the bottom of the av bay..
The expanding ball of gas from the e charge is going to shove the drogue down into the booster..
If you were to attach the drogue to the bottom of the av bay it would hinder separation..
The drogue couldn't move down into the booster tube AND the top half of the rocket move away at the same time if they are attached to each other..
If you attach the drogue down the boosters harness so it's a bit further down the harness then the distance from the top centering ring to the top edge of the booster the drogue will be free to be shoved down into the booster at the moment the echarge goes off without holding the payload section / av bay from moving away.. Then separation will freely occur with nothing holding the two halves of the rocket together.. At this moment the motor tube is empty,, in the bottom half of the rocket you have the drag of the fins and an empty motor tube,, all of the drag and none of the weight..
At this same moment in the top half you have all of the electronics and batteries and all of the recovery gear,, and the nosecone,, in this top half you have all of the weight and none of the drag...
These two halves will naturally,, try,, have a tendency to separate,, move away from each other..
The top half will drag the drogue out of the booster effortlessly...
The size of the drogue..
Without a drogue the rockets to sections flail around uncontrolled until the main fires..
There is no control over where the nose cone is pointed when the main fires..
If it is pointed down then the main is being fired into the path of the falling booster and harness..
This makes for the greatest risk of entanglement..
With a drogue the 2 sections should make an inverted “V”
with the drogue the top point as they fall from apogee..
With too big of a drogue the legs of the “V” are both hanging straight down..
This guarantees the main will be fired somewhere below where the payload section is..
This increases the chances of entanglement..
With a very small drogue the 2 legs of the “V” are spread wide..
This will make the nose cone point away from the booster and it's harness
while the rocket is falling from apogee..
This give by far the greatest likelihood that the nose cone will be pointed away from the rest of the rocket when the main fires.. And the least chance of entanglement..
In the payload section (the top half of the rocket, over the avionics bay),
the main parachute is attached directly to the hard point in the nose cone,
since it's pushed upwards, from underneath it.
Eliminating the necessity for the 3rd loop in the main chutes harness.
For this reason I use a 2 loop harness on top in the payload section...
I always use a longer harness in the booster then in the payload section..
The length is necessary in the booster because if the two separate parts at the apogee event are still moving away from each other quickly when they reach the end of a short harness the nose cone may pop off and you'll have a main deployment at apogee..
I like altitude ( as opposed to velocity )..
Because of this I like a fast as possible decent on drogue.
This is why I put the 3rd loop as close as I can to the av bay. Putting the 3rd loop as close to the av bay / payload section as possible gives the drogue leverage against the mass of the av bay / payload section..
So you can use the smallest drogue possible but still control the payload section.
With no drogue the payload section flails around uncontrolled during the decent from apogee..
Where it’s pointed when it fires is a hope and a prayer.
A small drogue holds it still, pointed out and away from the booster.
They will make the shape of an inverted “V” when falling..
The larger the drogue the narrower the legs of the “V” until you get to WAY too big or a drogue and both the booster and the payload section are hanging straight down from the oversize drogue.
Now the payload section is being held in place pointed straight down so it will fire the nose cone directly into the path of everything else falling.
Highly increasing the risk of entanglement.
Those that are proponents of flying drogue less have only used way too big of a drogue..
Please carefully check out these pics of a flight of “SteamPunk”’s..
http://onebadhawk.com/mars-8222015.html
The best jived out rocket I’ve ever seen is my 4” scratch “SteamPunk”.
It’s a big, heavy 4”, anywhere from 30 to 50 lbs on the pad according to what motor is in it..
The perfect drogue is 16”..
If it’s a particularly gusty day I’ll go a bit larger to a 20”..