Fruity Chutes - On Landing Bridal Release

Hi All, I've has this idea for awhile and now it's time to act. A common problem out west here is your rocket lands, the parachute fills with air and it's dragged for miles and miles. This can cause a lot of damage and even ruin your airframe and fins. My idea is really simple - to use the Tender Descender recovery tether in line with the chute and upon landing it separates. But the trickier issue is keeping the chute from then being blown away, or becoming a tangled mess.

The new Iris Ultra has a unique geometry that now makes this more practical. Normally for the Iris the center pull down strap mounts to the main bridal. To make this idea work the strap is separately mounted to the main shock cord QL. Now the main bridal with the shroud lines can separate, but the strap keeps the chute form blowing away since it's stays connected. Here are several pics of the prototype:


In this pic you see from left to right the shock cord, Tender Descender, Chute Bridal and then the shroud lines with the nylon strap in the center. Note that the strap separately runs down next to the bridal and ties off to the Shock Cord QL. The center pull also runs through a couple of extra QL's that act as guides for the bridal. This keeps the separated bridal from tangling.


This image show the assembly after separation. The bridal is now free to slide up the pull down collapsing the chute. The chute more or less turns itself inside out making it impossible to catch any air.

Upon recovery simply pull the bridal back down the strap, reconnect the QL's to the tether and your back where you were.

There are some challenges like running the wire up the inside of the shock cord, and stuff like that. I'll talk about that is future posts as I make these.

I plan to test this at Aeronaut at Black Rock in early August.

Nice approach. Hope your testing proves "fruitful."

Another aspect of this is to get an altimeter to detect landing. You can set up a Raven to trigger on the landing acceleration while the altitude is below the main chute deployment altitude.

A local project - Project Odyssey - used a sonic sensor to detect the ground and release the shroud lines - it worked perfect.

I've used a line cutter device to release the central line in my toroidal chutes and it has always worked well. I found it simpler than the AARD or tether for this purpose.

Edward

AlphaHybrids said:

A local project - Project Odyssey - used a sonic sensor to detect the ground and release the shroud lines - it worked perfect.

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When I first read this thread I thought it's a perfect place for a mini 5v Arduino, and a Parallax PING))) sensor. I've used heavier US range detectors hooked up to Arduinos for other prototyping purposes, but this seems like a great application for it.

I am guessing to build a quicky ground detection system you'd be looking at $50.00 including the Arduino and the US sensor.

Adrian A said:

Another aspect of this is to get an altimeter to detect landing. You can set up a Raven to trigger on the landing acceleration while the altitude is below the main chute deployment altitude.

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Hi Adrian, Exactly, at least that is my initial assumption. It would be very cool to have a self contained little unit that can be right in the bridal for this. But it needs to withstand the shock and pressure of deployment. Also be orientation independent.

Can the Raven do this on it's own with a little Lipo mounted in a little box on the bridal, is that what your thinking? Then I don't need to thread a wire up the shock cord.

I use the altimeter to trip my line cutter - I run my e-match charge through a piece of tubular kevlar that can't be pulled out.

An Arduino would be a good application. I believe they used a solid state solution that was armed by the main parachute pulling out.

I have also seen ones with a probe on the aft end that is pushed in and cuts the lines.

Edward

AlphaHybrids said:

I use the altimeter to trip my line cutter - I run my e-match charge through a piece of tubular kevlar that can't be pulled out.

An Arduino would be a good application. I believe they used a solid state solution that was armed by the main parachute pulling out.

I have also seen ones with a probe on the aft end that is pushed in and cuts the lines.

Edward

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Hi Ed, Can you be more specific what an "Arduino" is, maybe a link?

An Arduino is a type of programmable controller like PIC microchip. It has a while set of boards, etc and you can use a C type language to program it.

https://www.arduino.cc/

I learned on Motorola HC 6800 bit banging in hex code and now I use C for PIC chips. Really easy and smart controllers that you can do nearly anything with.

A friend and I have a project that uses one to throttle a hybrid motor.

Edward

When I was in the Army, when we were jumping, as soon as you hit the ground and did your PLF you popped one D ring on your chute to deflate it and prevent the chute from inflating again. So this makes perfect sense. Good idea!

If you used a 3 ring type system then the holding force doesn't have to be much at all.

Edward

Yeah you can use Arduinos for all kinds of prototypes (and production really). And the language to program them isn't that bad, although I'd be a lot happier if we had some more Python love in the MC world

Yes, they are nice. I've used them, but I mainly use the PIC family because that's what works and is cheap and easy.

Edward

eengelgau said:

Hi Adrian, Exactly, at least that is my initial assumption. It would be very cool to have a self contained little unit that can be right in the bridal for this. But it needs to withstand the shock and pressure of deployment. Also be orientation independent.

Can the Raven do this on it's own with a little Lipo mounted in a little box on the bridal, is that what your thinking? Then I don't need to thread a wire up the shock cord.

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I was thinking of keeping the Raven in a regular av-bay and running the wire up the shock cord, like Ed described. For bridle mounting, a 24mm av-bay could do the trick, but only if you could keep it nearly vertical during pre-launch and landing (180 rotation could be accomodated) and there's a good deal of altitude between the main deployment and the highest expected landing ground altitude. The ejection pressure could fool the altimeter into thinking it was already low enough unless the main deployment is pretty high and you were careful not to allow too much venting of the altimeter compartment.

With a Raven mounted in a regualar av-bay it can detect landing reliably, but it would be pretty iffy in a bridle-mounted location.

Arduino and Ping would be fun to try, but the most simple method will involve the use of altimeter that can already detect landing. The Raven sounds like it'd be the easiest way to do it, and I'd love to try that, some time when my budget permits.

I've watched my MAWD-telemetry equipped rockets land about 7 times while keeping an eye on the MAWD output, and the landing was synched up quite well with the "0 altitude" report from the altimeter each time. For a couple of flights I had a landing indicator - a loud buzzer attached to my receiver back at the rangehead - that worked quite well. I believe that a MAWD would report landing with enough reliability for a system like this - but unlike the Raven, would still need an external processor/circuit to fire the e-match in the Tether when landing was detected.

I think for now I'm just going to run a wire, keeps it simple (KISS). For this flight I'll be using an HCX - it's already in the av-bay as it's Comp 4.

I'm flying a M2600 Alumiflame in a 75/8000 case... Chute is my 72" Iris prototype. Should hit about 18K'...

If someone does know of a "off the shelf" landing detection system LMK your ideas. I really do mean off the shelf. A DIY engineering project I don't need, I'm just way too busy with Fruity Chutes...

What would be your thought about this,
At the rocket/ebay attachment point, use one of your "Y" harnesses, attach the single end to your ebay point,. Attach a shock cord to each end of the Y and run one of the y ends as you show in the separation pic attaching the chute center pull. Attach the transcender to the other Y point and run the second shock cord up to your main chute bridal/swivel.
Now the transcender is close to the ebay, dont have to run the wire very far, and the alitmeter able to do its thing being upright in the ebay. The transcender is out in the open and can deploy with out doing damage.
It "looks" like it would have the same effect you are going for.

Maybe you would not even need the y point and could use the transcender and two shock cords at the attach point and rig them at the chute points as you have shown in the pics.
I take it that the shock cords would have to be the same length to keep the chute in line and working properly. I dont know what , if any, issues would be with two cords.
Just a thought.

John

Hi jmac, everyone, keep the ideas coming!

I just threaded a twisted pair of multi-stranded wire up 6 yds of shock cord, not too hard. The tricky part is the nylon is going to have a lot more stretch than the wire. So I need to get at least 10 - 15% or so more wire into the cord... I need to think about how to do that.

I don't want to use Kevlar due to cost, and no stretch at all...

This idea could be modified to allow two stage recovery with a single chute. The "mis-adjustment" of the center line should work similar to the reefing of chutes in professional applications. The center line could be either too short or too long, whatever deploys nicer.
I bought a Tender Descender, with the intent of using it as a reefing device for conventional chutes, but I haven't yet started working on the idea.

Reinhard

I've used a similar design of chutes for a while, and if you have the apex line too long, you still get a good descent rate and good deployment. It's also hard to pull in cord to the right spot. With the apex line too short, it just flaps around in the wind and can tangle pretty easily.

I'll look back through my wind tunnel tests of the chutes, but I experimented with a bungee that pulled down the middle line a little. The bungee would stretch on nominal deployment and inflation, but once the load was gone it pulled down. It was very hard to find the right bungee material.

Here is the best way I've found to do dual deploy with a small drogue and regular chute from the same compartment.

https://tqc.yuku.com/reply/32424/2010-Balls-project#reply-32424


Edward

eengelgau said:

Bridal Release

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That brought a whole different image to mind :eyepop:

modeltrains said:

That brought a whole different image to mind :eyepop:

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I, too, was picturing white lace Fruity Chutes!

Adrian spelled it right, though!

-Ken