Monday, January 24, 2011

Mega Review: Parachutes

This post presents reviews of various parachutes, several of which were received via EMRR.  A couple are out-of-production (OOP) and are only included for historical purposes.

RocketChutes - Nylon Parachutes (12" and 18")
Aerocon - Surplus Nylon Parachutes (36" and 66")
Giant Leap - Spherachute PLUS+ (48")
OOP - RocketHead Rockets - Mylar Parachutes (12")
OOP - RocketChutes (unaffiliated with the previous manufacturer with this name) 18" Drogue

RocketChutes - 12" and 18" Parachute

I bought 12" and 18" rip-stop nylon parachutes in both the new 'Toucan/American Eagle' tie-dye and camo patterns. I received them just in time for NARAM-50. Far out, man! You can get them in many solid colors also and can even have them embroidered. Other sizes include 24, 30, 36, 42 and 48 inches.

These are well built little chutes. They have 6 braided nylon shroud lines (actually three looped to adjacent corners) that are firmly sewn to the canopy. The shroud line length is equal to the diameter of the canopy. The nylon is reasonably light but seems suitable for up to the max available diameter. The tie-dye chute's edges were hemmed but the camouflage chutes are the one style whose edges are hot-cut.

On all of these, I attached them to a snap-swivel. I flew them collectively about a half dozen times at NARAM-50. What can I say? They worked fine and just as importantly looked awesome. The tie-dye chutes are the only ones I've ever had that anyone took notice of (at least in these smaller sizes).

I wanted these unique patterns/colors and only checked the prices against my normal source of small chutes. The RocketChutes were just a tad less expensive and are constructed at least as well. I highly recommend these chutes. And, how can you resist that tie-dye pattern?

Aerocon - Surplus Nylon Parachute (36" and 66")

This a review of Aerocon's 36" and 66" white nylon chutes. Both are surplus chutes liberated from mortars, flares, etc.  I got these 'chutes as a prize from EMRR but at $6 and $12 each, respectively, these are a great value.  I just checked and after many years the price hasn't increased. 

The 36" chute is made from thin nylon and has nine 32 inch shroud lines made from 1/16 inch flat nylon. These are tied off and clamped with a metal brad. The ninth line is a reefing line that is attached to the middle of the canopy. Aerocon cites a book that states that a reefed chute can have the drag of a larger chute (44 inches in this case). I can't really vouch for that fact, but can say it works just fine, having flown it a couple of time is rockets such as my Estes Mercury Atlas. The chute comes with a cloth deployment bag and weighs 28 grams with that bag. I used a chute protector but did not use the bag.

The 66" chute is constructed from two panels of lightweight nylon. It is securely sewn and includes a 4" spill hole. It has a whopping 12 suspension lines, each 66" long. Aerocon states that these are 1/8 inch fiberglass and are fireproof. They feel like tubular nylon to me, but it doesn't matter much. The lines terminate in some larger tubular material, and there is one large loop to connect to. This one weighs 14 oz. with the 2 piece cloth deployment bag. It came inserted in the bag with the suspension lines folded neatly and secured with rubber bands. This picture isn't too good, but you can see additional photos, both in and out of the bag, on Aerocon's web site. I flew this chute one time on my Upscale Big Brute, which weighed about 8.5 lbs. at deployment. I didn't use the deployment bags, but left the lines folded and banded as delivered. It will never be as nicely packed again. The 66 inch chute worked great in this application.

Giant Leap - Spherachute PLUS+ (48")

The Spherachute PLUS+ is a true hemispherical panel chute. Here are the specifications, right off of Giant Leap's website:

* Tight, high density stitch, made to last!
* 400# test shrouds!
* Spill hole to reduce sway and drift.
* Strong ripstop nylon.
* Sharp contrasting 2-color design.
* Tried and proven!
* 1000# swivel already attached!
* Each chute comes with its own carrying case.

Here are some of my observations:

* There are eight 36" shroud lines
* The shroud lines are 1/8" circular nylon with inside cords (as best as I can tell)
* The shroud lines are stitched 3" up into the canopy
* The spill hole is 3" in diameter

Although some of the specifications are somewhat qualitative (How tight is tight? How strong is strong?), I have no doubt that this chute is sturdy enough for the typical rocket. On the other hand, it is not as strong as ones with tubular nylon sewn over the canopy.

Here are some quick comparisons:

Parachute Manufacturer Size and Type Shroud Lines 2004
Giant Leap TAC-1 48" skirted 4 - 1400 lb ½" tubular nylon over-the-canopy $49.99
Giant Leap Spherachute 48" hemispherical 8 - 400 lb cord, sewn 3" onto canopy $36.00
Giant Leap One Piece 48" round 8 - Flat nylon sewn on a few inches $20.49
b2 SkyAngle 44" skirted 3 - 950 lb tubular nylon over-the-canopy $56.99
b2 SkyAngle 52" skirted 3 - 950 lb tubular nylon over-the-canopy $71.99

This is not an exhaustive comparison, but it shows that the Spherachute is a mid range product, maybe not as durable as the chutes with over-the-canopy construction but better than the budget chute. Like the higher end products, it comes with a swivel and has a more efficient form factor than just a round chute.

Then, as I was writing this review, I referenced an article entitled "The Great Parachute Drift Off" written by Bruce Kilby (High Power Rocketry, December 1988). Bruce analyzed and tested 38 chutes from nine manufacturers. To quote his conclusions: "If price were no object, most of us would probably use the best, the strongest, and the most attractive 'chutes available....However, all the 'chutes tested passed the 50 MPH shock test. All the 'chutes can support your rocket for a gentle landing, and all the 'chutes tested have about the same drift rate. For the majority of flights the cheapest 'chute will work just as well as the most expensive 'chute tested."

To date I have flown this chute in my NCR Archer (recovery weight ~49oz) and my Upscale BLU-97B Cluster Bomb (a lighter 37oz rocket but has foamboard fins). The Archer deployed at apogee and the Cluster Bomb is light for this sized chute. I know these flights don't represent a 'stress test' for this product but it did work great.

RocketHead Rockets - Mylar Parachute (12")

This a review of a Rockethead Rockets' pre-assembled 12" Mylar parachute. These are no longer available.

The chute came packaged in a small bag and included a card with instructions and pricing on their chute line. The instructions merely say to place a drop of thin CA on each shroud line knot and to inspect the chute prior to launch. The chute itself is silver Mylar cut in an octagonal pattern. The lines are 12" long thin Kevlar®. On one end they are tied to holes in the chute, which are reinforced with circular tabs front and back. The chute also comes with a snap swivel.

I don't want make this brief review a comparison of Mylar vs. other materials, however, Mylar in general provides high visibility, some heat resistance, and tends to open better than plastic chutes. I have been using some 12" rip-stop nylon chutes in some models, but the Mylar packs better in the smaller diameter models. The pluses of this particular product are:

1. It comes pre-assembled (I don't particularly care for assembling chutes)
2. It comes with a snap swivel (I always use one anyway, both to avoid twisting and to move them from rocket to rocket)
3. With Kevlar® shroud lines the chute will be all the more forgiving if you don't put enough wadding in and will never break
4. With reinforcement of the connection points front and back, this chute will be about as tough as you will get with Mylar

I flew this chute twice in my FlisKits ACME Spitfire. The chute packed easily, which is good because I have a lot of shock cord in that BT-50 and there isn't much space left. The chute performed well on both flights, however on the second I proved that Mylar is not impervious to ejection gasses. I usually use a square (more for bigger tubes) of Estes wadding and some dog-barf to make a plug. This works well to protect my chutes. However, I repacked it hastily on the field - no Estes and not enough dog-barf wadding, it seems. Once corner of the chute was slightly damaged. I will use a bit of clear tape and the chute will be flyable.

RocketChutes - Drogue (18")

RocketChutes were made in Delaware and were available at Maryland/Delaware Rocket Association (MDRA) launches. They have been out of production for some time. They were extremely sturdy and an excellent bargains, offering a lot of "bang for the buck".

Here are the specs:

* Semi-ellipsoidal panel design - Chutes 60" and up have 8 panels, under 60" have 6.
* The canopy is made from mil-spec rip-stop nylon.
* The edges of adjacent panels are rolled into each other before taping
* All seams and edges are taped with 300lb. test, flat nylon tape.
* Shroud lines extend over and cross the spill hole
* The suspension ("shroud") lines are 300lb. test braided nylon (1000lb. test Spectra line on drogues).
* The suspension lines pass through and are box-sewn into a tubular nylon sleeve that forms a nearly indestructible attachment point to the recovery harness (except 18" drogues).

I bought an 18" drogue 'chute and was very happy with it. I used as a drogue on my 12lb. Landshark and as the main on several smaller rockets. The chute worked flawlessly in both applications. These chutes became more and more economical as their diameter increased. My chute cost a few of bucks more than an inexpensive single piece nylon chute, but is significantly more durable.