Jolly Logic Chute Release and Altimeter Three Systems on L-2 Attempts?

[Tom Zachman]

Has the Jolly Logic Chute Release System coupled with the a Jolly Logic Altimeter Three become the predominant deployment and flight recording mechanisms for L-2 attempts (assuming a "dual" deployment type advantage is desired over simple motor ejection charge parachute deployment) eliminating the need for a complex and expensive electronics bay?

 

[MClark]

No.

 

[viciouspeanut]

Chute release is a great option but it does not solve the issue of motors with no ejection or if a rocket needs a delay longer than the motor can provide. It isn’t too hard to need 20+ seconds and no motors go past 15-16 seconds.

So no, but they are great options for a ton of flight profiles but the motor ejection is still a limiting factor and the motor delays are not terribly accurate - plus an estimate from a sim at best of when apogee will be.

 

[Cameron Anderson]

JLCR is great if you want a truly redundant system...altimeter apogee primary, motor ejection secondary, second altimeter channel tertiary, then JLCR to unfurl the chute.
I like JLCR because they allow me to use a "dual deploy" from a single break in my airframe on my two-stage boosters.

 

[Nytrunner]

For my case, no. I wanted to build a large rocket with redundant deployment scheme for the practice.

 

[cherokeej]

Mark's right. No. This is rocketry. There is no one correct answer.

But it is one way to go. I signed a gentleman's L2 at LDRS last May that used a JLCR. Big fat rocket, full 54mm J, pop at the top, here it comes, and bloop! The JLCR did its job. The man fulfilled the requirements and earned the autograph.

That doesn't mean it's THE way to go. There's a big learning curve in rocketry, and there may come a time when you'll want to know how to build an av bay and use some of the more common electronic deployment systems.

Just something to keep in mind...

 

[Tom Zachman]

Mark's right. No. This is rocketry. There is no one correct answer.

But it is one way to go. I signed a gentleman's L2 at LDRS last May that used a JLCR. Big fat rocket, full 54mm J, pop at the top, here it comes, and bloop! The JLCR did its job. The man fulfilled the requirements and earned the autograph.

That doesn't mean it's THE way to go. There's a big learning curve in rocketry, and there may come a time when you'll want to know how to build an av bay and use some of the more common electronic deployment systems.

Just something to keep in mind...

Thanks for all of the comments. The responses are well reasoned with many points of view. Of course in rocketry there are multiple mechanical devices to execute planned flight profiles. Engineering solutions are multi faceted by definition.

In this case I fully recognize for example in Aerotech DMS type motors are limited to 14 second adjustable delays. Flights beyond those parameters are obviously beyond the capabilities of JL Chute Release.

Historically Jolly Logic Chute Release System is the heir apparent to the old cable cutter recovery devices. It is axiomatic that no one recovery system is “perfect” in all cases. In addition to my mind the Jolly Logic Altimeter Three is an easy and relative inexpensive altimeter to both use (with common digital devices) and mount. Using both devices in tandem for L-2 class rockets (for most flights) seems to be an excellent choice for data sampling and drogue-like recovery solutions.

The essence of my query is one of the progression of actual recent flight experiences in the L-2 class rockets given the fairly recent availability of the newer Jolly Logic systems. Bottom line is the trend line arching one way or another? Very interesting to review the responses. Perhaps the jury is still out. By the way for the record I have absolutely no contractual connection or financial interest with Jolly Logic and/or Aerotech or any of their employees.

 

[DavidMcCann]

There’s a different solution for every rocket to be sure.

The only part I find confusing is the JLCR/ALT3 being an alternate to “expensive” avbays....when a majority of my av bay setups have been cheaper than the proposed alternative....

 

[boatgeek]

There’s a different solution for every rocket to be sure.

The only part I find confusing is the JLCR/ALT3 being an alternate to “expensive” avbays....when a majority of my av bay setups have been cheaper than the proposed alternative....

I see where you're going with that. One nice thing about the JLCR is that there are basically no consumables (rubber bands are pretty cheap). While BP is not particularly expensive, e-matches can add up if bought commercially if you fly a lot. It will take a long time to add up to the cost delta between an RRC2 and a JLCR though. There's a mild counter-argument that the JLCR can be more portable between rockets than the average DD setup, but there's ways around that too. That said, I don't think anyone is in HPR because it's a cheap hobby!

To the OP, I would say that JLCR is becoming common but not not predominant. The biggest counter-argument to me is that there is no real way to do ejection redundancy with the JLCR. If the motor ejection doesn't do it, there's no backup to stop a lawn dart. If you add an altimeter for a backup apogee charge, you've added a lot more complexity and hassle. I fly HPR on the JLCR, but not much above a 36" chute.

 

[Banzai88]

JLCR is a mid step to true DD. Best utility=closer recovery for rockets that were previously nose blow pop and drop only.

On that note, I see it used mostly with younger fliers as a mid learning step to traditional pyro/electronic "true" DD and older guys bringing out other rockets that they haven't flown in years due to the relatively longer recovery walks required of nose blow.

In L2 attempts, or L2 flights in general in my area it's still pretty rare. Rare enough that a JLCR flight gets just a tiny bit less scrutiny than a cert or heads up flight, even when flown by acomplished and well respected fliers.

At 2 of my fields, I was the first and only owner for almost a year after it started shipping.

 

[manixFan]

I have a JLCR and have used it successfully a number of times. It’s a great way to reduce drift. Buts that’s all it really does, and for that it’s fairly expensive. It does not do anything else that a traditional altimeter does. In my experience it’s very easy to move between rockets and as long as I have a tracker, I can now fly bigger motors in my “nose blow pop and drop” (to borrow a great phrase from Banzai88) rockets due to the lower drift when I use a JLCR. It’s a neat device but I think think it’s wrong to equate it to an altimeter. Using it does not really help a flyer later use an altimeter that fires ematches.

But for a lot of my single tube rockets that fly to 3000’ and more, the JLCR is a great time saver on recovery. That makes it worth the price for me.


Tony

 

[Tom Zachman]

There’s a different solution for every rocket to be sure.

The only part I find confusing is the JLCR/ALT3 being an alternate to “expensive” avbays....when a majority of my av bay setups have been cheaper than the proposed alternative....

Good question. For discussion purposes to my mind the primary purpose for most av bays in L-2 class rockets was pyrotechnic recovery. Altimeter data was secondary. The initial cost of the entry level electronic bay and integrated components per se was just the start of the bean counting. Also looking at various av bay electronic systems vis-a-vis capability and reliability considerations caused the electronic component costs to rise quickly.

Further the the expense of drogue chutes, chute blankets as well as the ongoing costs of electric matches, gunpowder, batteries not to mention assembly time, component testing, and proper storage of explosives in a home environment were all part of the financial equation.

Additionally while assembling, testing, and maintenance of somewhat complex (to the average model builder) electronic components is a challenge and therefor fun to do, there might be the issue of creating more branches in your rockets potential recovery system failure tree.

Sadly in any engineering endeavor failure is always a possibility and is never free. The more complex the recovery system the higher the possibility of recovery malfunction which can cause loss or severe damage to the model and that really ups the cost analysis. That said would like to see more data in this regard.

Finally (although off the subject) as to integrated av bay electronic components the Bluetooth data retrieval of the JL Altimeter Three was a real plus to me something off the self entry level av bay electronics seemed in most cases to be missing.

Again thanks for your comments. Always consider carefully opinions from experienced rocketeers. As a side note plan to assemble an entry level av bay soon to get practice for more advanced rocketry.

 

[Tom Zachman]

I have a JLCR and have used it successfully a number of times. It’s a great way to reduce drift. Buts that’s all it really does, and for that it’s fairly expensive. It does not do anything else that a traditional altimeter does. In my experience it’s very easy to move between rockets and as long as I have a tracker, I can now fly bigger motors in my “nose blow pop and drop” (to borrow a great phrase from Banzai88) rockets due to the lower drift when I use a JLCR. It’s a neat device but I think think it’s wrong to equate it to an altimeter. Using it does not really help a flyer later use an altimeter that fires ematches.

But for a lot of my single tube rockets that fly to 3000’ and more, the JLCR is a great time saver on recovery. That makes it worth the price for me.


Tony

Sure. I was actually thinking about the JL Chute Release and Altimeter Three used together as a viable alternative to the somewhat complex and ongoing expense of assembling and maintaining av electronic component recovery/data retrieval systems in lower level motor L-2 class rockets.

If the ideal is to get your rocket higher and faster (and record the flight) with the least amount of hassle, the JL Chute Release and Altimeter Three combo seems to fit the bill for many L-2 class flight scenarios.

Of course while av bay electronic components vary widely in cost and are an absolute necessity in high level flight critical profiles I do like the concept of using an easy to mount (eg. on the shock cord) “dual deployment” like recovery system coupled with a off the self independent sealed altimeter to do the same thing as an av bay advanced pyrotechnic system. Plus you can move the JL device duo quickly from one body tube to another. A nice feature.

Appreciate you response and experience. Every bit of advice is most welcome.

 

[ericm541]

There’s a different solution for every rocket to be sure.

The only part I find confusing is the JLCR/ALT3 being an alternate to “expensive” avbays....when a majority of my av bay setups have been cheaper than the proposed alternative....

Agree, you can design A/V bay or just the sled to be used in different rockets and basic dual deploy altimeters are decently priced. I think its a viable alternative, if you want to spend the money you can do just about whatever you want, just do it safely of course. Eventually if you plan of going faster and higher than you will need something other than motor ejection.

 

[Nytrunner]

By the way for the record I have absolutely no contractual connection or financial interest with Jolly Logic and/or Aerotech or any of their employees.

Don't worry, John Beans is all of those things and we like him just fine

Worth noting, while mechanically simpler and easier to install, the chute release has it's own risk factors.
Band breakage (how many times have you used the band? Was it stored crimped? Will it let go on a cold launch day? Is it old and dehydrated?)
Increased tangle potential (is it tethered in a manner that it will release cleanly and depart from the chute? The flapping of the lines and device is highly unpredictable and difficult to test on the ground)
Early release (Is there enough tension in the chute bundle to keep it from slipping off? Is it tethered in a manner that the shock cord won't rip it off on initial deployment?)

That being said, one of that prevents me from owning one and using it in my rockets that don't have traditional flight computers.

 

[lowga]

For my L2, I flew a 54mm rocket with motor ejection along with a JLCR. It performed very well, and I'd recommend it for a certification attempt.

At a recent large launch, I saw dozens of successful JLCR flights, and three that failed to work properly. Likewise with traditional dual-deploy, mostly successful flights and some failures too. It's likely that human error accounts for nearly all the failures of both systems.

Within its limitations, the JLCR is a wonderful product. It's also safer than storing and using black powder.

=

 

[Eljay]

I'm planning on using one for my L2 (which will hopefully happen soon, getting a launch date around here can sometimes be challenging). I've been flying fairly short/beefy rockets and some of them would benefit from being able to run the occasional baby J (one of them in particular is kind of a pig frankly) so there's no real reason not to go through the L2 attempt process with motor eject + chute release since that's what I've been happy with for this class of rocket.

I have plans to do the more traditional 3" fiberglass as tall as I am dual deploy super redundant blah blah blah rocket, in fact I have one on order, but it's going to be a little while before I build it and I want to take my time testing it - I'll probably run it single deploy with both altimeter and motor charges on a L1 class motor to start, as an example, and there's no real timetable on when I'd actually be running it as a full dual deploy, or on a J, or any of that. I don't see any reason not to just kind of ease into it.

 

[cwbullet]

I believe in the KISS (Keep it simple) approach. As long as you understand that dual deployment with or without electronics increases your risk of failure, then I would sign off on your paperwork to do your level 2 (I used to be a prefect).

The good news is that it also increases you odds of landing on the field even if the chute fails to open. I have seen a lots of flight succeed and fail with the Jolly Logic. I think it depend on how taut the rubber band is (conjecture).

 

[Eljay]

The two main failure modes seem to be bad packing technique (always an issue) or wrong rubber band tension. Too loose and it will come off early, too tight and it may not release at all. Ground testing will detect if it's way off.

 

[Tom Zachman]

I believe in the KISS (Keep it simple) approach. As long as you understand that dual deployment with or without electronics increases your risk of failure, then I would sign off on your paperwork to do your level 2 (I used to be a prefect).

The good news is that it also increases you odds of landing on the field even if the chute fails to open. I have seen a lots of flight succeed and fail with the Jolly Logic. I think it depend on how taut the rubber band is (conjecture).

Sounds like excellent advice to me. Field experience is the best “simulation run”. From my very limited launch observations I do concur on the need for attention to detail on parachute packing and rubber band tension for successful JL Chute Release operation.

 

[Tom Zachman]

The two main failure modes seem to be bad packing technique (always an issue) or wrong rubber band tension. Too loose and it will come off early, too tight and it may not release at all. Ground testing will detect if it's way off.

For sure!

 

[Tom Zachman]

I'm planning on using one for my L2 (which will hopefully happen soon, getting a launch date around here can sometimes be challenging). I've been flying fairly short/beefy rockets and some of them would benefit from being able to run the occasional baby J (one of them in particular is kind of a pig frankly) so there's no real reason not to go through the L2 attempt process with motor eject + chute release since that's what I've been happy with for this class of rocket.

I have plans to do the more traditional 3" fiberglass as tall as I am dual deploy super redundant blah blah blah rocket, in fact I have one on order, but it's going to be a little while before I build it and I want to take my time testing it - I'll probably run it single deploy with both altimeter and motor charges on a L1 class motor to start, as an example, and there's no real timetable on when I'd actually be running it as a full dual deploy, or on a J, or any of that. I don't see any reason not to just kind of ease into it.

Good luck on you L-2 attempt!

 

[Tom Zachman]

For my L2, I flew a 54mm rocket with motor ejection along with a JLCR. It performed very well, and I'd recommend it for a certification attempt.

At a recent large launch, I saw dozens of successful JLCR flights, and three that failed to work properly. Likewise with traditional dual-deploy, mostly successful flights and some failures too. It's likely that human error accounts for nearly all the failures of both systems.

Within its limitations, the JLCR is a wonderful product. It's also safer than storing and using black powder.

=

Excellent observations. Hope to follow your lead.

 

[Nytrunner]

The two main failure modes seem to be bad packing technique (always an issue) or wrong rubber band tension. Too loose and it will come off early, too tight and it may not release at all. Ground testing will detect if it's way off.

Don't leave out: "Forgot to turn it on"

 

[Tom Zachman]

Amen!

 

[Eljay]

Don't leave out: "Forgot to turn it on"

Oh, yes, thank you. With its close cousin "You have to turn it back on after ground testing it?"

 

[Banzai88]

The two main failure modes seem to be bad packing technique (always an issue) or wrong rubber band tension. Too loose and it will come off early, too tight and it may not release at all. Ground testing will detect if it's way off.

Don't leave out: "Forgot to turn it on"

Oh, yes, thank you. With its close cousin "You have to turn it back on after ground testing it?"

And it's distant cousin, "nose cone fits tight enough that if you move it in and out a few inches, it'll draw enough vacuum to trigger it before launch".

 

[lowga]

The Jolly Logic Altimeter also has to be set into "ready for launch" mode--not just turned on prior to launch. I'd recommend a short checklist related to the Jolly Logic components.

Do remember that after ground testing, you have to turn it back on, and reprogram it for your desired altitude. Then be careful putting it into the rocket.

Good luck on L2!

 

[Eljay]

Bottom line is you need to treat it as carefully as packing the chute, installing the ignitor, etc. etc. Be very consistent about how you do it every single time.

 

[Tom Zachman]

And it's distant cousin, "nose cone fits tight enough that if you move it in and out a few inches, it'll draw enough vacuum to trigger it before launch".

As to video camera start-up on my L-1 attempt guilty as charged. The day was very cold and windy and my fingers felt like ice cubes. Had a check list but once the bird was placed on the rail before vertical alignment all I was thinking was please fly straight and true. Probably could not have pressed those tiny buttons in sequence and time before set up but definitely can not throw any rocks. Lesson learned,but the day ended well with certification success.