At what speed will a Top Flight X-Type parachute shred?

Subject says it all. I'm looking to get an idea of what speeds Top Flight X-Type drogue parachutes (both standard and Ultra lines) can reach before the parachute fails. I'm looking to use them in a couple projects that will have deployment at or near the jet stream so ideally I'd like some idea as to what speeds those parachutes can reach before failing.

Yes, I'm aware that RocketMan makes a ballistic Mach II parachute but space will be at a premium in the flights I've got planned and those specific chutes look a bit bulky. Hence my preference to look at the Top Flight line first.

Any comments would be appreciated.

In my opinion, that question can have a lot of different answers. Are you planning on deploying while you still have a high vertical velocity?

I don't believe the jet stream, or winds aloft will effect your deployment much. You rocket will be drifting relative to those winds.

I just picked up a 24" ultra X-type, and those lines are thick. Its a very heavy duty chute.

But as to what speed it would fail at. That would all be a close estimation. The math could be done on shroud line and fabric strength. But how fast will your drogue open? How do you fold it? Your rocket is already slowing down as soon as it splits at deployment. Before your drogue is even inflated.

I think that most parachute damage comes from rapid opening. Slider rings, deployment bags, and folding techniques can all reduce the chance of chute failure if you have a below optimal deployment.

Eric said:

I think that most parachute damage comes from rapid opening. Slider rings, deployment bags, and folding techniques can all reduce the chance of chute failure if you have a below optimal deployment.

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^^^ This. ^^^

Eric said:

Are you planning on deploying while you still have a high vertical velocity?

I don't believe the jet stream, or winds aloft will effect your deployment much. You rocket will be drifting relative to those winds.

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What Eric said. You could deploy in 500 mph winds but if your rocket is drifting on those winds, the wind relative to the rocket would be almost zero and would have little to no effect on drogue deployment. Wind speeds are measured relative to a spot on the ground, not the rocket moving in the air mass.

Please correct me if I'm wrong but as I understand it a rocket nearing apogee (and thus decelerating) in high winds would "nose into" the wind as the rocket would still be stable, the fins would be producing lift, and the vehicle would orientate itself nose first into the wind before the deployment event occurs. Then the apogee event would occur, the NC would fire forwards into the wind, and all the laundry would be pulled out. Once the drogue inflates the rocket would have a short sharp change in direction and start travelling with the wind instead of into it. That change of direction is what has me concerned as I suspect that will be the point of peak load on the chute. That's where I expect it will fail if it does fail.

Here's a snippet of the AeroPac 100k' Carmack Prize report that seems to support what I'm referring to.

Eric said:

Are you planning on deploying while you still have a high vertical velocity?

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No, I'm not.

Eric said:

I think that most parachute damage comes from rapid opening. Slider rings, deployment bags, and folding techniques can all reduce the chance of chute failure if you have a below optimal deployment.

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If you have any advice with regards to how to fold a X-Type chute to minimise chute failure I'd really appreciate it. I will not be utilising slider rings or a deployment bag.

plugger said:

Please correct me if I'm wrong but as I understand it a rocket nearing apogee (and thus decelerating) in high winds would "nose into" the wind as the rocket would still be stable, the fins would be producing lift, and the vehicle would orientate itself nose first into the wind before the deployment event occurs. Then the apogee event would occur, the NC would fire forwards into the wind, and all the laundry would be pulled out. Once the drogue inflates the rocket would have a short sharp change in direction and start travelling with the wind instead of into it. That change of direction is what has me concerned as I suspect that will be the point of peak load on the chute. That's where I expect it will fail if it does fail.

Here's a snippet of the AeroPac 100k' Carmack Prize report that seems to support what I'm referring to.

No, I'm not.


If you have any advice with regards to how to fold a X-Type chute to minimise chute failure I'd really appreciate it. I will not be utilising slider rings or a deployment bag.

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I can send you any info you'd like regarding the ultra x-type chutes. Folding of these chutes is very easy, they are very heavy duty, and will withstand your needs. Anything you need, please ask!

Preston

you could add "tapped" breakpoints. Acts like a shock absorber for your shock cord.



Tony

pnobile said:

I can send you any info you'd like regarding the ultra x-type chutes. Folding of these chutes is very easy, they are very heavy duty, and will withstand your needs. Anything you need, please ask!

Preston

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Thanks Preston. Effectively I'm just after a bit of advice from someone with experience with these chutes at deployment speeds around 100mph. Regardless your price is right and I'll be placing an order in the next 2-4 weeks. I've got a 36" X-Type of yours that I purchased years ago but I've never used it and won't now as it's a bit big for my needs. Still, from a high speed drogue perspective they do seem to be the sweet spot from a speed and size perspective.

tfish said:

you could add "tapped" breakpoints. Acts like a shock absorber for your shock cord.

Tony

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Cheers Tony, I hadn't considered that!

plugger said:

Thanks Preston. Effectively I'm just after a bit of advice from someone with experience with these chutes at deployment speeds around 100mph. Regardless your price is right and I'll be placing an order in the next 2-4 weeks. I've got a 36" X-Type of yours that I purchased years ago but I've never used it and won't now as it's a bit big for my needs. Still, from a high speed drogue perspective they do seem to be the sweet spot from a speed and size perspective.

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The standard x-type is not specifically designed for the speeds your looking at, but are still great parachutes for other applications.

The ultra x-types are designed and constructed for the speeds you're looking at. You will not be disappointed! We ship all orders within 1-3 business days.

Anything else you may need, please ask us!

Preston

pnobile said:

The standard x-type is not specifically designed for the speeds your looking at, but are still great parachutes for other applications.

The ultra x-types are designed and constructed for the speeds you're looking at. You will not be disappointed! We ship all orders within 1-3 business days.

Anything else you may need, please ask us!

Preston

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Thanks for that Preston. Any chance you'd be willing to make me a couple 10" Ultra X-Type parachutes?

plugger said:

Thanks for that Preston. Any chance you'd be willing to make me a couple 10" Ultra X-Type parachutes?

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No problem, we will make anything you'd like! Please email us direct for custom orders....you'll be happy with the prices and shipping times!

Just visit our website and click on the email address at the top of the page to place custom orders!

Thanks

Preston

pnobile said:

No problem, we will make anything you'd like! Please email us direct for custom orders....you'll be happy with the prices and shipping times!

Just visit our website and click on the email address at the top of the page to place custom orders!

Thanks

Preston

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LEGEND. I'll be in touch shortly.

Preston's service is amazing. From emailing back and forth at 10pm Friday night. He made my chutes exactly the way I wanted, and I had them on Monday afternoon.

plugger said:

T Effectively I'm just after a bit of advice from someone with experience with these chutes at deployment speeds around 100mph.

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I guess I'm still not understanding how you are going to be deploying at 100 mph if you are doing an apogee deployment? The rocket will slow at apogee, but that doesn't mean it will tilt into the wind. Relative to the rocket, there may not be any wind. If it's moving with the air mass the relative wind speed to the rocket is zero. It doesn't matter how fast the air mass is moving.

Watch rockets ascending on windy days. When they leave the pad, they travel vertical, but they are also moving down wind at the same time because they are also start moving with the air mass as they ascend. Wind cocking only occurs near the ground when the rocket first leaves the pad because it isn't moving relative to the air mass yet and the wind speed relative to the rocket is almost as high as it is to the pad.

With a high flight, I would be surprised if the wind relative to the rocket was any higher than 10 mph, if that much, because by the time the rocket reaches apogee, it will be moving very close to the same speed as the air mass it's in since it's had so much time to pick up that motion.

plugger said:

Subject says it all. I'm looking to get an idea of what speeds Top Flight X-Type drogue parachutes (both standard and Ultra lines) can reach before the parachute fails. I'm looking to use them in a couple projects that will have deployment at or near the jet stream so ideally I'd like some idea as to what speeds those parachutes can reach before failing.

Yes, I'm aware that RocketMan makes a ballistic Mach II parachute but space will be at a premium in the flights I've got planned and those specific chutes look a bit bulky. Hence my preference to look at the Top Flight line first.

Any comments would be appreciated.

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It's not really a question of what speed but what pressure can a parachute survive. Do you have an idea of what the expected max q (dynamic pressure) is going to be during this flight? Once you figure that out you can easily calculate the max forces. It may not be at opening but during its descent. Then I would either conduct qualifying test or contact the manufacturer to see if the chute is rated for that q. If it is going to be a high q deployment then you not only have to worry about line attachments but also seam strength and material strength. Hope this gives you a good starting point.

The winds aloft above 25,000' (AGL) were over 100mph one day this year at BALLS (I recall at about 120mph). Other than causing a lot of drift I don't recall anyone having issues with apogee deployment. Many deployments at BALLS occur in the jetstream and I can't recall anyone ever being concerned about the drogue. I suppose it's a good thing to think about but I suspect if it was a problem there'd be a lot more discussion about it. Handeman's explanation seems reasonable to me.

On the other hand, if an overly stable rocket really weathercocks into the wind and picks up a large horizontal velocity, that's a different matter. I've got a lot of video showing chutes getting shredded at deployment from that. But that is based on the rocket's velocity, not the wind.

In this case I would defer to empirical evidence. Based on many past flights the wind speed at deployment speed does not seem to add any additional stress on the drogue. Recovery distance, that's another thing!


Tony

Does the parachute care if it's being deployed at 100 mph on it's way down do to missed apogee event or if the rocket actually went straight up, stopped and then started a tail slide then deployed into a 100mph jet stream?

The chute still needs to with stand the same affect during it's inflation

edited part; I think the altimeter's "deployed at speed. would only show one of these events. Your G's and velocity would show both.

This looked like a mellow flight from the ground




Tony

tfish said:

Does the parachute care if it's being deployed at 100 mph on it's way down do to missed apogee event or if the rocket actually went straight up, stopped and then started a tail slide then deployed into a 100mph jet stream?

The chute still needs to with stand the same affect during it's inflation

Tony

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Yes, the parachute cares. Material, hardware and seam selection are based off of max potential forces and then given margins of safety. Most of the time the highest forces are either the opening shock or snatch force. An apogee deployment can place the max forces after inflation and during the descent. For all except the snatch force the forces are directly associated with the dynamic pressure. This pressure changes with speed and ambient air density. When talking about a cross wind deployment like the jet stream there are even more issues to consider. Then ballistics and parachute sailing come into play. I don't know what the flight profile looks like but know the max q during the descent from apogee is the best starting point to determine what forces are involved. Then a determination can be made on if the chute is structurally strong enough to survive.

tfish said:

Does the parachute care if it's being deployed at 100 mph on it's way down do to missed apogee event or if the rocket actually went straight up, stopped and then started a tail slide then deployed into a 100mph jet stream?

The chute still needs to with stand the same affect during it's inflation

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Tony, the point I was trying to make is that deploying at apogee in the 100 mph jet stream is not the same as deploying at 100 mph vertical speed, going up or down. The reason is by the time the rocket reaches apogee, it will be moving about 100 mph along with the jet stream because it is being blown along and the relative speed between the rocket and the air will be very close to zero.

Go with the Top Flight chute they have a 27 year track record of making great chutes.

I agree with Handeman. Let’s do a quick thought experiment:

You are on a tall building with two rockets. You drop one rocket and it becomes stable nose down. You wait for it to be falling at 100mph and fire the drogue. What happens?

You have a second rocket set up to launch. The wind is blowing 100mph. You launch the rocket but the motor hard chuffs hard and only goes up a couple hundred feet and the drogue deploys at apogee. What happens?

It’s clear that a rocket falling at 100mph and deploying the chute is not the same as a rocket flying in a 100mph wind at apogee. At apogee, the forces acting on the chute and rocket are the same - wind and gravity. The rocket is free to move in the same direction as the wind and indeed as it nears apogee it will be influenced by the wind and start moving with it. When the chute opens the rocket is free to move along with it - it’s not a hard stop. So the stresses are not even close to equivalent. I believe if the two events were equivalent we'd all be well aware of it. Yet I've never heard anyone mention their drogue failed due to high winds at apogee.

My interest in all this is that I am starting to fly into the JetStream as well. Obviously I want to recover my rockets intact. So this discussion has a direct influence on how I would select my drogue and deployment systems. But of course we should each do what makes the most sense to us.


Tony

Handeman said:

I guess I'm still not understanding how you are going to be deploying at 100 mph if you are doing an apogee deployment? The rocket will slow at apogee, but that doesn't mean it will tilt into the wind. Relative to the rocket, there may not be any wind. If it's moving with the air mass the relative wind speed to the rocket is zero. It doesn't matter how fast the air mass is moving.

Watch rockets ascending on windy days. When they leave the pad, they travel vertical, but they are also moving down wind at the same time because they are also start moving with the air mass as they ascend. Wind cocking only occurs near the ground when the rocket first leaves the pad because it isn't moving relative to the air mass yet and the wind speed relative to the rocket is almost as high as it is to the pad.

With a high flight, I would be surprised if the wind relative to the rocket was any higher than 10 mph, if that much, because by the time the rocket reaches apogee, it will be moving very close to the same speed as the air mass it's in since it's had so much time to pick up that motion.

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I think this is where we're coming unstuck so to speak. In the image I posted from the Aeropac 100k report above you'll notice that the rocket "noses into" the wind nearing apogee. I say this because as soon as the apogee event occurs the rocket under drogue starts following the path of least resistance, aka the wind direction. So I believe you and I aren't seeing eye to eye because our beliefs regarding what occurs at apogee is fundamentally different.

And as Tony mentioned, windspeed in the Jet Stream can easily reach 100mph, as it did during one of the days at BALLS this year. See the Black Rock chart below which highlights both windspeed and direction can vary greatly dependent on altitude.



So, to recap, my expectation is that as the rocket approaches apogee it will be bleeding vertical velocity but gaining horizontal velocity against the wind (once again, check out the picture). So when the baro deployment event does occur (a little after apogee mind you) the drogue will "catch" in the wind and cause a short, sharp change in direction nearly 180 degrees in the opposite direction. Once again, I do believe that's what the picture i posted above demonstrates. And that sudden sharp change of direction is what was concerning me.

manixFan said:

The rocket is free to move in the same direction as the wind and indeed as it nears apogee it will be influenced by the wind and start moving with it.

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Whereas from my understanding momentum and positive stability will cause the rocket to "fly into" the wind, not along with it.

Another way to describe it is that "apogee weathercocking" is probably a thing, in so far that the rocket is moving at a relatively low speed when compared to the wind impacting upon it and thus turns into the wind quite similar to a rocket that weathercocks off the pad.

And finally, Preston is making me a couple of the Ultra X-Type chutes in 10" form factors. Hopefully I'll have them as well as the 18" and 24" I've ordered in hand soon. And just to close the circle so to speak before this I had Top Flight Thin Mill 9" and 12" chutes on deck to for my plans. I feel much more comfortable now.

Preston's service was phenomenal. Gotta love Top Flight folks...

plugger said:

I think this is where we're coming unstuck so to speak. In the image I posted from the Aeropac 100k report above you'll notice that the rocket "noses into" the wind nearing apogee. I say this because as soon as the apogee event occurs the rocket under drogue starts following the path of least resistance, aka the wind direction. So I believe you and I aren't seeing eye to eye because our beliefs regarding what occurs at apogee is fundamentally different....<snip>

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I was at BALLS this year and flew 2 flights on Sunday (14,500' and 19,500') when the winds aloft were very high. (According to your chart the 19,500' flight deployed into 75mph winds.) I don't recall anyone mentioning anything about shredding a drogue due to the winds even though there were many flights to that altitude. When Debra mentioned the 100mph winds at the flyers meeting no one seemed concerned other than recovery distances would be a bear.

plugger said:

....<snip>...So, to recap, my expectation is that as the rocket approaches apogee it will be bleeding vertical velocity but gaining horizontal velocity against the wind (once again, check out the picture)..<snip>

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I'm sorry but I think that defies the laws of physics. How can a rocket gain horizontal velocity against a 100mph wind without a propulsive force behind it as it loses vertical momentum? At that point the only forces acting on it are gravity and the wind. We've all seen a bird moving backward while trying to fly into a headwind. Why would the same thing not happen to the rocket, especially when there is nothing to push it against the wind?

I think what you are really asking is "can winds aloft shred a drogue on deployment"? It seems that based on empirical evidence I would say the answer is no, that the winds will act upon the rocket as it approaches apogee and the rocket will be moving with the wind when the drogue deploys. If that were not the case I believe this issue would have come up long ago.

Of course no harm in using a very sturdy drogue and taking all parameters into consideration. And please take this discussion as it is meant - to simply think through your question and the premise it is based on. We each have our opinion on it and I find it worthwhile to try and reason things out against someone who is willing to put time and effort into supporting their position as you have done.

In the end of course you won't regret having a good drogue so it doesn't really matter who is right. But I like to try and understand what happens during a flight and your question opened up an avenue I hadn't thought of before.


Tony

I agree completely with Tony. Not only about the wind, but about discussions and using a sturdy drogue.

I have found that many people don't understand the effects of wind or air on parachutes and rockets. Mostly because their normal reference is on the ground where we live. But if you talk to sky divers, you can get a different perspective because they spend time in the air mass and have practical experience us earth bound types don't. Wind is nothing but the mass of air moving. Once a rocket gets in that mass, it quickly takes on the movement of the air mass and the relative difference becomes small. As plugger said, the rockets tend to tip into the wind at apogee because the vertical velocity is so small that even a small horizontal force can make it weathercock into the wind. What you have to remember is that by the time the rocket reaches apogee, it's ground speed horizontally is going to be almost the same as the wind, thus the long recovery distances on windy days, and the wind relative to the rocket will be very low and dropping.