SKLZ Speed Chute

[RoyAtl]

Saw one of these while walking through Sears the other day. X-form factor, mesh instead of shroud lines. Has anyone tried to use one in a rocket of, say, 5 to 20 pounds?

 

[troj]

Looking at the picture, I doubt the construction is up to the task.

The load put on a chute from a person running versus a deployment even slightly off apogee are entirely different.

-Kevin

 

[RoyAtl]

Of course the loads are different, but how do you think that chute won't work just from the photo?

 

[crossfire]

I have seen one used before as a main chute. It never opened. The netting seems to not allow enough air for the chute to open.

 

[troj]

Of course the loads are different, but how do you think that chute won't work just from the photo?

I think the risks of it failing catastrophically are too high.

-Kevin

 

[MClark]

It is only $30, buy one, test it, report here.
No need to risk a rocket. Tie a weight to it and drop off a bridge or other high place, does it open, fail, descent rate.....

If I used it as designed it would drag on the ground

M

 

[RoyAtl]

I have seen one used before as a main chute. It never opened. The netting seems to not allow enough air for the chute to open.

Do you remember anything about the flight, how big it was, how fast it was going at deployment, stuff like that? If it's designed to open at running speeds, maybe the problem was the way it was packed?

 

[Worsaer]

Or perhaps it's not intended for use in a rocket...

 

[RoyAtl]

Or perhaps it's not intended for use in a rocket...

Obviously, since it is being sold as a runner's training assist, and not a rocket parachute. The whole point in my line of questioning is to see if someone has tried it as a rocket parachute, what their experiences and problems were, and see if maybe those problems could be solved, maybe with some simple modification either to the physical traits of the product, or to the protocols used. Maybe there is additional capacity in the chute, maybe not.

If it has not been tried, *then* I might consider purchasing one to try it. If it has been tried, and the user could tell me about obvious show-stopper problems, *then* maybe I would not consider purchasing one, or I might try to solve the show-stoppers.

But I'm sorta surprised at the, "nah, doesn't look like it'll work so I'll say it won't work" attitudes.

Years ago I used a LOC 50" chute in a rocket. The chute stayed packed all the way down. Shroud lines unfurled; the canopy just didn't catch air. If someone had seen that flight, and it was the only flight they'd ever seen with a LOC chute, would they have walked away thinking, "That chute shouldn't be used in rockets."? No, that would have been absurd. Instead, I changed the way I folded the chute, and every flight afterward, the canopy promptly snapped open.

 

[TopRamen]

Obviously, since it is being sold as a runner's training assist, and not a rocket parachute. The whole point in my line of questioning is to see if someone has tried it as a rocket parachute, what their experiences and problems were, and see if maybe those problems could be solved, maybe with some simple modification either to the physical traits of the product, or to the protocols used. Maybe there is additional capacity in the chute, maybe not.

If it has not been tried, *then* I might consider purchasing one to try it. If it has been tried, and the user could tell me about obvious show-stopper problems, *then* maybe I would not consider purchasing one, or I might try to solve the show-stoppers.

But I'm sorta surprised at the, "nah, doesn't look like it'll work so I'll say it won't work" attitudes.

Years ago I used a LOC 50" chute in a rocket. The chute stayed packed all the way down. Shroud lines unfurled; the canopy just didn't catch air. If someone had seen that flight, and it was the only flight they'd ever seen with a LOC chute, would they have walked away thinking, "That chute shouldn't be used in rockets."? No, that would have been absurd. Instead, I changed the way I folded the chute, and every flight afterward, the canopy promptly snapped open.

I agree. I'm quite surprised at how quick to dismiss the Idea the Responses have been in this Thread. It's almost as if there was some sort of Hidden Agenda.

 

[cwbullet]

I own one for athletic endeavors. I will give it a try and report back.

 

[jcato]

I agree. I'm quite surprised at how quick to dismiss the Idea the Responses have been in this Thread. It's almost as if there was some sort of Hidden Agenda.

It's called "Xenophobia" (and before you xenophobes out there dismiss *this* (along with the parachute), go look it up...

https://en.wikipedia.org/wiki/Xenophobia

... it's more than just prejudice against race.)

It also explains a lot.

-- john.

 

[troj]

In my case, it's called "Recovery is one of the most critical aspects of what we do, so I tend to be highly selective of the parachutes I'll use, or recommend someone use".

I've seen too many chutes have minimally attached shroud lines tear off on a hard deployment.

This is akin to the whole discussion around bent-wire eyebolts. Lots of people say "I've never had one fail, so they're fine". I've never had one fail, myself, but I've witnessed several that have.

It's called playing the odds. I'll stack the odds as much in my own favor as I can. That means recovery components that are more robust, and better able to deal with an early or late deployment. At the same time, I'll never recommend someone fly something that I wouldn't put in a rocket of my own.

The real test of that chute isn't a nominal deployment like tossing it off a bridge. The real test is something more akin to a late opening -- put some shock load on it.



-Kevin

 

[MClark]

. Snipped-The real test of that chute isn't a nominal deployment like tossing it off a bridge. The real test is something more akin to a late opening -- put some shock load on it.
-Kevin

This is the bridge I use. I can get over a 300' free drop before deployment. Attached to a weight may times the rocket I can get plenty of shock

 

[g zilla]

Has anyone tried a parachute off of a drag car. Obviously for large rockets im sure you could buy a used one cheap from a race team

 

[Rocketjunkie]

Has anyone tried a parachute off of a drag car. Obviously for large rockets im sure you could buy a used one cheap from a race team

I have one. It weighs 15 lb.

 

[jcato]

Somehow, I knew you'd respond. That's OK, because I fundamentally agree with your position. I was planning on editing my post and adding a 'p.s.' or two - but we'll just do it here...

In my case, it's called "Recovery is one of the most critical aspects of what we do, so I tend to be highly selective of the parachutes I'll use, or recommend someone use".

More hobbyists should share your view, IMO. A lot of problems in recovery would disappear in that case - as this situation of recovery failures is (my view) the literal worst hazard in the hobby.

I've seen too many chutes have minimally attached shroud lines...

... which describes the vast majority of parachutes in the hobby (unless something's drastically changed).

... tear off on a hard deployment.

...too many...

Why is that?

It was actually this point that was in mind when I made the reference to xenophobia. It just struck me as a little irrational to be picking apart this 'running chute' while at the same time continuing this situation of the 'Tape Dot Approach' to parachute construction (i.e. mimicking Estes parachutes on a larger scale - which is about all zig-zagging the suspension lines into the skirt really is).

Rip-stop was never designed nor intended to serve as a 'structural component' in a recovery system (I might would want to say 'structural material', but the very act of functioning as it was designed will generate forces that must be dealt with - so 'component' is meant to convey a more robust, specifically designed part). Rip-stop is just supposed to generate drag and then transfer the stresses thereby to a (real) structural framework (tape, suspension lines run continuously, etc). But, with 'Tape Dot' canopies, the hobby is asking rip-stop to serve a function it was never intended to do. Now, the (repeated) failures begin to make more sense.

It just seemed (again) a little irrational to argue about the quality of construction of this 'new' chute, when 'quality of construction' in more conventional canopies (in the hobby) is almost of no concern (as one must assume).

Is that xenophobia that prevents the practitioners from abandoning this old (clearly inadequate) way of canopy construction or just laziness? Either one seems bad to me (and I would have thought the hobby would have moved beyond this by now.)

[As to this running chute, I feel it could, relatively easily, be beefed up into something useable (and, no, many would not do it -- they're all looking for a 'buy-it-n-fly-it' approach -- and, for sure, a $30 canopy couldn't be made THAT good). But that's neither here nor there. I'm assuming widespread sewing skills that may not be there.]

This is akin to the whole discussion around bent-wire eyebolts.

Remember bungee cord? Remember how practically everyone fought tubular nylon tooth-n-toenail? ("I need that stretch to absorb the shock of the nose cone hitting the end!!" [not if you design it correctly]). My, how times have changed.

*That* is xenophobia.

... and better able to deal with an early or late deployment.
<snip>
... The real test is something more akin to a late opening

One should always be conservative in this -- as I am fond of saying, "Murphy was an optimist." And it's never easy to balance a prudent, conservative approach against resistance to change - no argument there.

A early (or late) deployment means some failure in (pre-)flight knowledge of how the flight was to play out. With all the simulation software available today (even free), it's nearly inconceivable that one would fail to predict apogee correctly (ignoring all the electronic devices now available). What is most needed (to mesh with all these advancements) is accurate and reliable information as to the delay times of the power plant (to best match the simulations). And, yet, TMT doesn't (and NAR does) give that to you, correct? I've got no idea if that is xenophobia or not.

I would have thought the hobby would have moved beyond this, as well.

(I'm well aware that electronics are playing an ever increasing role in this - which is good. However, there are still many, many situations where the classic 'pyro delay' is still used - witness their continuing commercial availability.)

... and better able to deal with an early or late deployment.
<snip>
... The real test is something more akin to a late opening

That's within the hobby's power to correct... on several fronts. Here's to the hope it'll be sooner rather than later.

-- john.

 

[G_T]

Even a correct prediction of apogee or a correct measure of apogee does not in any way guarantee a low velocity. The maximum velocity in a practical sense is what the motor can achieve with the rocket in a near-horizontal flight profile (burnout at about apogee in this case). Anything between 0 speed, and that nasty high speed flight vector, is possible. Near zero is what usually happens, it is the nominal case, but one should not count on it!

Gerald

 

[cwbullet]

I have looked at mine and they built similar to drogues / pilot chutes for cargo chutes.

 

[troj]

I have looked at mine and they built similar to drogues / pilot chutes for cargo chutes.

Can you post pictures, please?

-Kevin

 

[jcato]

Even a correct prediction of apogee or a correct measure of apogee does not in any way guarantee a low velocity. The maximum velocity in a practical sense is what the motor can achieve with the rocket in a near-horizontal flight profile (burnout at about apogee in this case). Anything between 0 speed, and that nasty high speed flight vector, is possible. Near zero is what usually happens, it is the nominal case, but one should not count on it!

All true - but then I believe you will find that the minimum (*relative*) velocity in any given flight will be the top of the parabola - regardless of that parabola's shape (i.e. narrow and tall - or wide and flat). There may be situations with certain motors where this 'Vmin' would occur at some point prior to apogee (I haven't done any analysis, so I can't state with certainty) - but I'm almost certain one would not find any lower velocity AFTER the point of apogee. The more I think about it, I think it would be rare to see it before apogee as well.

With barometric sensing, apogee will be rather accurately found and I would guess that - using pyro delays (time from first motion), they would tend to run long on the wide, 'rainbow' flights - but, again, I haven't done any analysis on that point.

Regardless of the dearth of data at my disposal , I still think the top of that parabola is where one will find the minimum velocities (with the minimum of recovery system loading) - which is important to know. You may not have a choice of *how minimum* - but after the vehicle leaves the pad, you pretty much have to live with what you get - and it's important to make is as minimum as you can.

-- john.

 

[troj]

Regardless of the dearth of data at my disposal , I still think the top of that parabola is where one will find the minimum velocities (with the minimum of recovery system loading) - which is important to know. You may not have a choice of *how minimum* - but after the vehicle leaves the pad, you pretty much have to live with what you get - and it's important to make is as minimum as you can.

Agreed.

Stack the odds in your favor - deploy the recovery system at the slowest velocity you can.

-Kevin

 

[G_T]

The recent N5800 somewhat horizontal flight may well have had its minimum velocity after apogee. That's the sort of situation to which I was referring. Anyway I wasn't talking about when to deploy, just that one shouldn't count on the rocket being slow.

I've had approx 200mph horiozontal apogee speed once, due to hitting some nasty wind shear within a couple hundred feet of clearing the rail on a decently fast rocket. Shredded, but recovery held everything together. Deployment was 1 second late, which in this case was a benefit as the rocket was still slowing down past apogee.

One shouldn't count on the deployment happening at apogee either. It should, yes, but always? No.

Gerald