Pilot Chute vs Streamer

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My recommendation would be to build and fly the rocket according to kit directions at least once to gain some experience, then begin trying your ideas systematically.
I've always like the idea of using a slider to allow the chute to open more gradually.
The other problem you might face is that you intend for your rocket to come down at high speed before deployment and then very gradual deployment. You'll have to convince an RSO that it's safe. If your rocket doesn't gain the altitude you expect, either due to weathercocking or rod whip or bad luck, you may not ever have a deployment. Many RSOs might reject that. You'd do better to deploy at apogee and allow your slow deployment to occur from there. If something goes wrong at least it won't be nose down and making that funny whistling sound we all have come to adore.
I read about the anti zipper harness. I'm not sold on it; I guess I'd have to see it work. It still looks like the Kevlar lines can slice the body tube if it's nose down and whistling.
No matter what I would love to see video. The G-Force is a fun rocket. Leave out the thrust block and the motor hook so you can use an H motor and certify.

Steve Shannon
 
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My recommendation would be to build and fly the rocket according to kit directions at least once to gain some experience, then begin trying your ideas systematically.
I've always like the idea of using a slider to allow the chute to open more gradually.
The other problem you might face is that you intend for your rocket to come down at high speed before deployment and then very gradual deployment. You'll have to convince an RSO that it's safe. If your rocket doesn't gain the altitude you expect, either due to weathercocking or rod whip or bad luck, you may not ever have a deployment. Many RSOs might reject that. You'd do better to deploy at apogee and allow your slow deployment to occur from there. If something goes wrong at least it won't be nose down and making that funny whistling sound we all have come to adore.


Steve Shannon

Steve, you might adore the "death whistle", but it scares me @#$%less when I can't locate the incoming ballistic.

I am kind of with some others here in that a streamer might not provide enough drag to pull the bag clear but a small pilot chute may be better. If this rocket is being flown at a club event you will indeed have a hard time convincing an RSO that it would be a safe flight profile.
 
My recommendation would be to build and fly the rocket according to kit directions at least once to gain some experience, then begin trying your ideas systematically.
I've always like the idea of using a slider to allow the chute to open more gradually.
The other problem you might face is that you intend for your rocket to come down at high speed before deployment and then very gradual deployment. You'll have to convince an RSO that it's safe. If your rocket doesn't gain the altitude you expect, either due to weathercocking or rod whip or bad luck, you may not ever have a deployment. Many RSOs might reject that. You'd do better to deploy at apogee and allow your slow deployment to occur from there. If something goes wrong at least it won't be nose down and making that funny whistling sound we all have come to adore.
I read about the anti zipper harness. I'm not sold on it; I guess I'd have to see it work. It still looks like the Kevlar lines can slice the body tube if it's nose down and whistling.
No matter what I would love to see video. The G-Force is a fun rocket. Leave out the thrust block and the motor hook so you can use an H motor and certify.

Steve Shannon

Really good point. I might need to just make it slow from apogee for that reason. If it's moving slow, there won't be enough force to remove the parachute from the bag, but it also won't be aerodynamic anymore. Bonus not having to worry about zippers. Thanks.
 
How do you feel about the zipperproof harness link I posted above? This is our first kit rocket. All others are scratch built fiberglass so these concerns are definitely new to me.

That's ingenious but if one doesn't get the rod angle right and the rocket goes off the flight profile, the risk is higher that the harness will rip through the tube.
If the tube was indestructible fiberglass, the concern would be the harness being sliced. Believe me, I had a modified Talon 2 come in ballistic because I missed a
leg on the ematch with an out of production altimeter that only gave a single continuity warning, ie. the warning is the same with one ematch as it is with two.
The failure mode is if one had one ematch connected or one is bad or connected incorrectly, there is no way of knowing what is wrong.
I launched, the apogee match failed, the rocket came in unseen ballistic and the main fired. The cardboard tube broke the 400lb test harness, the nosecone was longitudinally sliced by a G10 fin and surprisingly the main chute somehow had a delayed opening and didn't show any sign of stress. I got the main chute, nosecone and broken segment of the harness back. Got the rest of the remains 18 months later. You can't under estimate the forces at work here. Kurt
 
That's ingenious but if one doesn't get the rod angle right and the rocket goes off the flight profile, the risk is higher that the harness will rip through the tube.
If the tube was indestructible fiberglass, the concern would be the harness being sliced. Believe me, I had a modified Talon 2 come in ballistic because I missed a
leg on the ematch with an out of production altimeter that only gave a single continuity warning, ie. the warning is the same with one ematch as it is with two.
The failure mode is if one had one ematch connected or one is bad or connected incorrectly, there is no way of knowing what is wrong.
I launched, the apogee match failed, the rocket came in unseen ballistic and the main fired. The cardboard tube broke the 400lb test harness, the nosecone was longitudinally sliced by a G10 fin and surprisingly the main chute somehow had a delayed opening and didn't show any sign of stress. I got the main chute, nosecone and broken segment of the harness back. Got the rest of the remains 18 months later. You can't under estimate the forces at work here. Kurt

Wow, that's crazy. After processing all the info in this thread, we're going to test & keep the deployment bag, but have separation at apogee and just focus on dialing in the slow opening from there. It just doesn't seem like the risk of high speed deployment is worth it.
 
Wow, that's crazy. After processing all the info in this thread, we're going to test & keep the deployment bag, but have separation at apogee and just focus on dialing in the slow opening from there. It just doesn't seem like the risk of high speed deployment is worth it.

I applaud your willingness to accept advice from others.
 
I'd love to take credit for maturity, but the truth is my daughter would be pissed if I broke her rocket and then I'd get that look from the wife.

I've inadvertently had fiberglass rockets go off profile, arch over, start a dive and after 1 to 4 seconds of unplanned ballistic descent, get the main deployment. This used to happen more with incorrect rod positioning and a viciously weather-cocking rocket. I now simulate the daylights out of rockets under different windy conditions to get an idea of the behavior
in the wind. I then fly at a large venue and point the rail downwind to try to have the rocket arc up into the wind to lead to the lowest velocity apogee I can achieve.

The other advice to heed here is save for and get a Jolly Logic Chute release. It will save you your cardboard rockets. I just flew a cardboard ASP WAC Corporal: https://www.asp-rocketry.com/ecomme...ge-29-38-mm-Version-.cfm?item_id=631&parent=8 on a 38mm AT H242 with a Zeptomag
MAD unit: https://www.tindie.com/products/ZeptoBit/zeptomag/ (I can vouch for the owner as I've purchased two of them on different occasions).
Last flight was last Saturday. The nosecone sits on a coupler which has the space for the Zeptobit, battery, terminal block on the bulkhead for the ematch and
a locking toggle switch pointing aft on the bulkhead. This kit begs for MAD deployment.

This is an old rocket I've had for 8 years (looks exactly like the one the youngster is holding in the picture) and just completed a rebuild due to a harness snag and a distal tube repair. I did the sims, sized the charge and used the Jolly Logic Chute release. Stuck in a 14 second delay so I had tracking smoke for as long as possible but since the charge was controlled by the MAD unit, I didn't need to worry about the exact delay as the motor was plugged. Once the rocket tips over and the MAD unit detects the change in the lines of the Earth's magnetic lines of force, the ematch is fired. Best chance of a low velocity ejection. The JLCR unfurled the chute at roughly 800 feet.

I only caught glimpses of flashes off the shiny paint but really wasn't able to localize the rocket until the Jolly Logic chute release unfurled the bright yellow parachute.

Really, if you want to do pseudo dual deploy with motor eject, buy some different delay grain sizes, learn to drill them to modify the delay if needed and invest in a
Jolly Logic Chute release. Then........ You can fly your rocket with a lot more assurance you aren't going to zipper the thing

With the restrained chute, one has more leeway with early and late apogee deployments. I still wouldn't trust it in a cardboard rocket with the ballistic descent like you
proposed as the package still has mass and that can aggravate the zippering effect if it's a very late deployment. A little early or a little late, no sweat! Kurt
 
I'm sure you've figured what your going to try by now but I'll chime in anyway.

To original question I don't think a streamer would cause enough resistance to be able to pull the line loose and slowing the deployment, just logically I'm thinking will need to be a small canopy of some sort.

Before I was certified and going to launches - I just launch LPR at my house and I admittedly would use the longer delays so the rocket was past apogee and on its way back down so I could land it closer to the pad. There was always that ...ooohhhh moment - then pop, out the Chute came and not much floating - so I get where your going. The more I pushed it - I got real tired of zippers, then I reinforced tube and started slicing the harness. Ok, so let's thicken everything up...This was completely reckless looking back, but just an open farm field and not very high flights - so only harm was to the rockets. Going to a real launch and learn - not a good plan - the rocket just can't come down in a ballistic fashion, big cardinal rule. So apogee is where it has to happen, but can certainly fall fast after that.

I'm interested in learning what you find, there is definitely something there and sounds like you have a lot of cool experience where I don't. Just got to happen safe, worse feeling at a launch, bringing your whole family to the launch and your all hanging out under the canopy and hear " HEADS UP HEADS UP, One COMING IN HOT!" As I desperately jump out from under the canopy straining to locate said rocket and get my family out of the way. So I totally get why some reply the way they do.

Looking forward to seeing your results, I might wind up with a new willingness to try D bags, I've been resisting.
 
I'm sure you've figured what your going to try by now but I'll chime in anyway.

To original question I don't think a streamer would cause enough resistance to be able to pull the line loose and slowing the deployment, just logically I'm thinking will need to be a small canopy of some sort.

Before I was certified and going to launches - I just launch LPR at my house and I admittedly would use the longer delays so the rocket was past apogee and on its way back down so I could land it closer to the pad. There was always that ...ooohhhh moment - then pop, out the Chute came and not much floating - so I get where your going. The more I pushed it - I got real tired of zippers, then I reinforced tube and started slicing the harness. Ok, so let's thicken everything up...This was completely reckless looking back, but just an open farm field and not very high flights - so only harm was to the rockets. Going to a real launch and learn - not a good plan - the rocket just can't come down in a ballistic fashion, big cardinal rule. So apogee is where it has to happen, but can certainly fall fast after that.

I'm interested in learning what you find, there is definitely something there and sounds like you have a lot of cool experience where I don't. Just got to happen safe, worse feeling at a launch, bringing your whole family to the launch and your all hanging out under the canopy and hear " HEADS UP HEADS UP, One COMING IN HOT!" As I desperately jump out from under the canopy straining to locate said rocket and get my family out of the way. So I totally get why some reply the way they do.

Looking forward to seeing your results, I might wind up with a new willingness to try D bags, I've been resisting.

That makes sense. We just made the first two launches here at home. This is the setup we tested & used.

Weight without motor: 48.3oz
Stability: .9 calibers with motor installed
1 inch launch rail length: 97 inches
Wind speed: 10mph, 2mph gusts

-24 inch pilot chute with 23 inch lines attached to d bag by 41 inch harness.
-Main chute crown attached to inside of d bag by another 41 inch harness.
-42 inch main chute with 45 inch lines attached to nose by 10 inch harness.
-Nose attached to 19 inch booster harness by 203 inch elastic shock cord.

The first flight, ejection occurred as planned at apogee, but the nose didn't separate due to binding of the shoulder. However, the nose slide out about 1 inch which made it unstable so it tumbled instead of flying. It hit the ground on its side with no damage about 200ft downwind of the pad. I greased the shoulder for the next flight.

The second flight, I made a mistake drilling the delay. Ejection occurred about 2 seconds after apogee when it was completely nose down. Luckily, the recovery system performed flawlessly. Full inflation of the main chute occurred close enough to the ground that it didn't fully decelerate the rocket, but it's a lot of chute for the rocket weight so there was no damage. It weather cocked a good amount and landed about 100ft upwind of the pad. There were no broken rubber bands on the d bag or damage from nose down deployment.
 
Talcum powder is a good dry lubricant for rocketry.

Thanks, I'll give that a shot. The grease worked great and it's all we had at the time, but the cleanup wasn't fun. I've never used anything on the fiberglass rockets. Something about the tub flexing on the shoulder end was the issue I think.
 
Thanks, I'll give that a shot. The grease worked great and it's all we had at the time, but the cleanup wasn't fun. I've never used anything on the fiberglass rockets. Something about the tub flexing on the shoulder end was the issue I think.

The most common cure for a fiberglass rocket that doesn't separate well is sandpaper and/or a larger charge of black powder. Ground testing is our friend.


Steve Shannon
 
Talcum powder is a good dry lubricant for rocketry.

Tell me about it:eyeroll: That successful WAC flight above I did talcum powder and saw the white puff at altitude. I next flew a formula 54 on a 29mm H250 with a JLCR and an
EggFinder in the Nosecone. Didn't feel the need to talcum the chute as it was warm out. Am trying to fine tune and acquire more tracking skills with the ISM trackers. Launched, rocket disappeared as planned (goes about 3300') and never saw it again. The Eggfinder plotted it on my APRSIS32 app on the tablet and showed it about 15 feet off the access road about 1000 feet north of me. The patch antenna on a 10 foot pole was getting a signal so I knew the tracker survived. I walked up to it and the JLCR did its job but the chute was stiff and didn't open! I picked up the harness and it fell open. I had reset the CR from 800' to 600', the temp was the 50's (not like the 20's this weekend) and the package was clear of the chute protector with no tangling of the harness. Next time, will saturate the chute canopy with talcum powder and rub it in. I've done that in the past and I believe it helps with a stiff chute. Oh, the rocket is fine (fiberglass, G12 TTW fins) with the tumble recovery as it landed in fine, freshly plowed, Central Illinois farm ground. Lesson learning without damage is nice I tell you.

Talcum is a mess with the canopy but by golly it helps. The only other thing I find helpful but is extremely messy is to rub powdered graphite into a chute protector side that is in contact with the body tube in a situation where the chute pack is an extremely tight fit in a rocket. In that case, it's good to do the pack just before the flight and use gloves and have baby wipes to get the black stuff off your hands. I talcum the chute liberally before packing in the protector. I also do not leave a tightly packed chute to sit in the rocket for extended periods.
The creases that are acquired over time can inhibit filling of the canopy by making it stiff. I have some chutes that have a lot of folds and find "talcumming" them improves the reliability. Yes, technically store chutes open if possible and avoid wadding 'em up for storage. Kurt
 
Tell me about it:eyeroll: That successful WAC flight above I did talcum powder and saw the white puff at altitude. I next flew a formula 54 on a 29mm H250 with a JLCR and an
EggFinder in the Nosecone. Didn't feel the need to talcum the chute as it was warm out. Am trying to fine tune and acquire more tracking skills with the ISM trackers. Launched, rocket disappeared as planned (goes about 3300') and never saw it again. The Eggfinder plotted it on my APRSIS32 app on the tablet and showed it about 15 feet off the access road about 1000 feet north of me. The patch antenna on a 10 foot pole was getting a signal so I knew the tracker survived. I walked up to it and the JLCR did its job but the chute was stiff and didn't open! I picked up the harness and it fell open. I had reset the CR from 800' to 600', the temp was the 50's (not like the 20's this weekend) and the package was clear of the chute protector with no tangling of the harness. Next time, will saturate the chute canopy with talcum powder and rub it in. I've done that in the past and I believe it helps with a stiff chute. Oh, the rocket is fine (fiberglass, G12 TTW fins) with the tumble recovery as it landed in fine, freshly plowed, Central Illinois farm ground. Lesson learning without damage is nice I tell you.

Talcum is a mess with the canopy but by golly it helps. The only other thing I find helpful but is extremely messy is to rub powdered graphite into a chute protector side that is in contact with the body tube in a situation where the chute pack is an extremely tight fit in a rocket. In that case, it's good to do the pack just before the flight and use gloves and have baby wipes to get the black stuff off your hands. I talcum the chute liberally before packing in the protector. I also do not leave a tightly packed chute to sit in the rocket for extended periods.
The creases that are acquired over time can inhibit filling of the canopy by making it stiff. I have some chutes that have a lot of folds and find "talcumming" them improves the reliability. Yes, technically store chutes open if possible and avoid wadding 'em up for storage. Kurt

I'll add my 2c worth of opinion
here since this is one of my specialties.

1) For ripstop nylon, you absolutely SHOULD store the canopy packed just like it will be before deployment. This encourages the canopy to "remember" how it should be packed. This helps ease packing in the future. HOWEVER, you SHOULDNT use the packed parachute after storage. Unpack the parachute, shake it out, inspect and REPACK immediately prior to launch in order to avoid deploying a brick of nylon.

2). New zero porosity ripstop nylon is impregnated with silicone by running through high pressure rollers. It is slick to the point of being frustrating to pack. It WONT hold shape and slips all over itself. If your new parachute is stiff, the fabric is waaaaay too thick & heavy duty for parachute use. Parachutes should be thin with strength provided by strategically placed reinforcement tape. If it's an old parachute that is no longer slick, there are many silicone sprays sold for tent waterproofing that can be used to rejuvenate the fabric. Case in point, I just bough an Estes pro series 24" parachute to use as the pilot simply because I saw it at the hobby store and the price was right. The fabric is thick and it's stiff. Bad parachute material and design, but I like it specifically because it doesn't want to inflate!
 
Keith,

For what it's worth, testing has shown no noticeable difference in deployment speed or reliability on reserve parachutes that have been packed for up to 25 years. In fact some military personnel reserves are vacuum packed and then destroyed after 25 years.

However I agree and I keep my canopies packed but repack them before flight.
 
Keith,

For what it's worth, testing has shown no noticeable difference in deployment speed or reliability on reserve parachutes that have been packed for up to 25 years. In fact some military personnel reserves are vacuum packed and then destroyed after 25 years.

However I agree and I keep my canopies packed but repack them before flight.
If it's a lot of data points over 25 years, I bet that data is based on F-111 material. The zp nylon may be different although that's just a guess. I think storage temperature is the main issue. Nylon in a 120f loft or forgotten in a trunk during a hot summer day gets pretty soft with the individual fibers litteraly forming a new shape during stress relief. Then when it cools off, some of the fabric can actually stick together.
 
As far as I know there is only one reserve made of ZP, a Raven MZ, so yes the testing is based on F111.

Not a lot of benefit to using ZP in a small rocket canopy. ZP is primarily used to create a more rigid ram air canopy in skydiving, it also creates a slower decent areas in rounds, so might possibly help some, but very little in a small canopy.
 
As far as I know there is only one reserve made of ZP, a Raven MZ, so yes the testing is based on F111.

Not a lot of benefit to using ZP in a small rocket canopy. ZP is primarily used to create a more rigid ram air canopy in skydiving, it also creates a slower decent areas in rounds, so might possibly help some, but very little in a small canopy.
Makes sense. I imagine any cd increase from a zp round would be negated by the need for a larger vent hole.
 
UPDATE!

Changes:
1) The cheap 42" chute was useless for the task and even with the 24" pilot, the rocket still descended too fast. I stuck with a 42", but got a higher CD Fruity Chutes round.
2) We also changed the rocket orientation so the lighter nose lands before the booster hitsmaking it a bit easier on the swept fins.
3) For the slider, what worked best was using a simple 19mm ID steel ring, pushed all the way to the skirt.
4) 200mg smokeless powder added to ejection charges.
5) All motor delays drilled for deployment at apogee.

Deployment Bag Testing:
During ladder testing, I was unable to get the entire rocket off the ground before all the lines pulled free from the deployment bag stowes. Going for worst case scenario, I intentionally line locked two random bights. Both of the rubber bands broke, allowing the chute to deploy.

Slider Testing:
Simulations showed a descent rate of 24mph with only the pilot chute out. To be safe, assuming the sniveling main and other stuff will create extra drag, I tested at 15mph from a sun roof.

The deployment bag and sequence were removed from the equation and we focused only on a predictable time for the main to inflate, still pulled by the pilot, and with slider starting at the skirt. On average, the main inflated in 316ft@15mph.

Additional Factors:
-The rocket will probably fall faster than 15mph under the pilot, which will increase deployment speed.
-The deployment bag added will slow the opening.
-The main will open faster in vertical orientation with the addition of gravity pulling the slider down.

Next steps:
-Launch with G53, slider down, to check the deployment bag with new main. With the slider up, the main might not open before impact.
-Launch with G64, slider half up to check opening speed.
-Launch with G76, slider against skirt and go from there.

This is BY FAR, my girl's favorite rocket!
 
UPDATE!

Changes:
1) The cheap 42" chute was useless for the task and even with the 24" pilot, the rocket still descended too fast. I stuck with a 42", but got a higher CD Fruity Chutes round.
2) We also changed the rocket orientation so the lighter nose lands before the booster hitsmaking it a bit easier on the swept fins.
3) For the slider, what worked best was using a simple 19mm ID steel ring, pushed all the way to the skirt.
4) 200mg smokeless powder added to ejection charges.
5) All motor delays drilled for deployment at apogee.

Deployment Bag Testing:
During ladder testing, I was unable to get the entire rocket off the ground before all the lines pulled free from the deployment bag stowes. Going for worst case scenario, I intentionally line locked two random bights. Both of the rubber bands broke, allowing the chute to deploy.

Slider Testing:
Simulations showed a descent rate of 24mph with only the pilot chute out. To be safe, assuming the sniveling main and other stuff will create extra drag, I tested at 15mph from a sun roof.

The deployment bag and sequence were removed from the equation and we focused only on a predictable time for the main to inflate, still pulled by the pilot, and with slider starting at the skirt. On average, the main inflated in 316ft@15mph.

Additional Factors:
-The rocket will probably fall faster than 15mph under the pilot, which will increase deployment speed.
-The deployment bag added will slow the opening.
-The main will open faster in vertical orientation with the addition of gravity pulling the slider down.

Next steps:
-Launch with G53, slider down, to check the deployment bag with new main. With the slider up, the main might not open before impact.
-Launch with G64, slider half up to check opening speed.
-Launch with G76, slider against skirt and go from there.

This is BY FAR, my girl's favorite rocket!

Glad it worked.

Odds are the .2g of smokeless powder probably did little or nothing to help with ejection. Smokeless powder needs much better containment to be as effective as FFFg black powder. It for the ease of use and consistency most us prefer BP.
 
Smokeless powder has been tried many times. Without significant pressure containment it can't build up enough pressure to burn completely. 4fg black powder is preferred by far with 3fg coming in second. BP substitutes can work also.
 
Smokeless powder has been tried many times. Without significant pressure containment it can't build up enough pressure to burn completely. 4fg black powder is preferred by far with 3fg coming in second. BP substitutes can work also.

Thanks, it's just what I had already and I was paranoid after it failed to separate. I wonder how ball milling the smokeless would affect burn rate. Obviously it's easier to just pick up a bottle of black powder and I don't even own a ball mill, but still curious. I've been using the 200mg mixed in with the regular Aerotech charge and not just by itself.
 
All the tests I've read about are for straight smokeless. A hybrid powder like you're trying might be interesting. I have no idea what that result might be. Ground testing is the best test.


Steve Shannon
 
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