BALLISTICALLY DEPLOYED PARACHUTES REVISITED
The purpose of this article is to provide pilots with an update on issues and safety practices as related to ballistically deployed parachutes. I will not address the pros and cons of parachute deployment systems or parachute canopy designs. I will try to focus on issues directly related to the use and abuse of ballistic deployment systems for hang gliding.
At the time of this writing, 1996 has already seen 3 incidents involving pilots flying with ballistic deployment systems. The following descriptions by no means cover all the ramifications and details of the accidents but merely focus on issues relevant to this article.
April 1996 Scott launched without taking off the safety on his rocket. While attempting an aerobatics maneuver at a high altitude, his glider tumbled. He went for the parachute handle and remembered having not released the safety. He attempted (with gloves on) to release the safety, grabbed the handle a second time and yanked as hard as he could. His yank ripped the rocket off the harness. He dropped the rocket and manually opened his parachute container and extracted the parachute. The parachute opened at 200.
May, 1996 Walter had been flying about an hour when he heard a "flopping sound" over his shoulder. He realized his parachute had started to slip out of the parachute container and attempted to fly to the LZ. 30 seconds later he heard a loud "shot" and felt his glider decelerate. He was flying with a fully inflated parachute in tow. Upon inspection of the system it was evident that the launch tube (rocket) had been ripped off his harness and the rocket had fired. It is unclear as to in which order that occurred.
May 1996 James, in an attempted aerobatics maneuver, tumbled once and started to spin. While spinning, he reached down to pull his deployment handle. The rocket had been ripped off his harness. James found the rocket, tried to point it into clear air and shot the rocket. He spun into the trees and used his parachute to climb down. (Incidentally, James only injury was the burns on his hands from trying to slide down his parachute to the ground. Apparently sliding down the canopy and lines worked fine but when he reached the 1" tubular webbing bridle he gained lots of speed. If he ever had to do that again he recommends tying knots in the bridle aid in the climb.)
All three incidents involved the rocket, mounted on the hip of the pilots harness, being ripped off. All three pilots had systems that were attached to the harness by 4 steel bolts. In two incidents the rocket probably caught on something that ripped it off the harnesses. In Scotts situation his ability to rip the rocket off his harness may have saved him from serious injury or worse.
What lessons do these experiences teach us? Emergency situations i.e. tumbles, are violent. Rockets mounted onto the hip area of the harness can get caught on parts of the glider and pulled with substantial force. Rockets that are bolted onto the harness, as opposed to sewn on, may be more prone to getting ripped off the harness. A rocket can be accidentally activated. A pilot, with presence of mind can react to emergency situations with creative solutions (and lots of adrenaline). An accidental deployment can happen even when we least expect it.
ACCIDENTAL DEPLOYMENTS INVOLVING BALLISTICALLY DEPLOYED PARACHUTE SYSTEMS
* In the past year three accidental deployments have involved freshly packed ballistically deployed parachutes. In one incident the parachute remained attached to the rocket mounted on the pilots hip and formed a giant horseshoe. The rocket never fired and the pilot was able to successfully fly a circle around the parachute and land. He bent two down tubes on impact. The second incident involved the parachute starting to slip out of the parachute container and the pilot able to hold it in long enough to go land safely. In the third incident, as noted above, the rocket fired after the parachute had started to come out of the container and the pilot found himself flying at a .5 glide ratio over trees with a fully inflated parachute in tow. One unsubstantiated story involved a pilot reaching for the cord on his pod harness used to open the doors. Apparently when he reached for the cord to open his harness, he pulled the cable that connected the parachute to the rocket and his parachute started to escape.
What can we learn from this? First, freshly packed parachutes retain air and pack larger than parachutes that have been packed a few weeks. After every repack it is very important to do a "knee test". * Velcro closures which may appear secure, can open easily when the harness is loaded. Freshly packed parachutes contour to the shape of the parachute container when the pilot is in the harness. Although sitting on the freshly packed parachute when it is first placed into the harness can help "squeeze out" some of the excess air, it will not assure the pilot that the parachute is secure. As the curve of the pilots body loads the harness it can pull the parachute container Velcro apart. Because of the curvature of the pilots body coupled with the way the Velcro is attached to the container, Velcro thought to be secure with the shear strength may actually be in the peal mode. This will not hold the parachute in the container. The best way to check this is to do the knee test.
Speaking of Velcro, As Velcro is used its strength degrades. As it gets older it degrades. If it is wet it loses strength. At least two other reports of accidental deployments (full and partial) have been due to weak Velcro. In one case the pilot was on final glide and the parachute inflated as the pilot flared. In another case the pilot noticed his parachute starting to come out of the container in time to stuff it back in and land without incident. The point here is that if you have an older harness, you may need to replace your Velcro.
BALLISTIC SYSTEMS AND HARNESS ATTACHMENTS
We may never know for sure just why we are seeing rockets ripped off harnesses now, where we have never had reports of that happening before. We can only speculate and try to prevent it from continuing.
What we do know is that some failures seems to be at the grommet harness attachment points. The grommet attachment appears to be through the harness material only. The grommets are ripped off the harnesses with the rockets. It would be fair to assume that an older harness with significant abrasion and UV exposure would be more prone to this type of problem.
We also know that failures have been at the point where the canister is sewn to the flat material that is attached to the harness.
Some remedies are:
Have your rocket sewn to your harness with proper thread, stitch size, reinforcement and stitch pattern. Have the launch tube stitching reinforced.
Sew a reinforcement plate inside the harness. The reinforcement plate should allow all 4 bolts from the rocket to be secured to that plate. This will not reduce your chances of getting the rocket caught on the glider, but it will take more force to rip the rocket off the harness with the full reinforcement plate.
BALLISTIC SYSTEMS AND HARNESS MOUNTING LOCATION
The best location for a rocket to be mounted onto a harness has long been a subject for debate. On one hand you want the handle to be with in easy reach, but on the other hand you do not want any body parts susceptible to getting in the way of the firing rocket. On one hand you want the rocket pointing into clear air, but on the other hand you do not know where that air might be. On one hand the rocket must be clear of any harness ropes or open doors to work properly, on the other hand that is not always possible since the pilot is in a different body position on launch and landing than he/she is in flight not to mention the positions encountered during an emergency situation.
The bottom line is that there are always compromises. The secret is to minimize your risk of complication. To do that consider these questions:
In flying position what do you have on your harness that may interfere with the rocket having a straight line shot into clear air? Are there pockets on your harness, loose cords or lines?
In launch or landing position, will the open doors on your pod get in the way?
Are any of your body parts more likely to get into the line of fire i.e. can your hand or arm reach in front of the rocket, are your legs in the way of the rocket at any time during a normal flight?
These questions are particularly important when developing your own Standard Operating Procedures (Sops) in the event of an emergency. Although there may not be a perfect position for every situation, you should be aware of the limitations of your harness arrangement.
One pilot, several years ago, was fully aware that with his hip mount if he ever had to use his rocket right after launch, he should try to get as head down as possible so the rocket would not shoot towards the ground. When he launched and his "home made"glider went into a screaming dive, his first action was to get head low before he pulled his activation handle.
Having this clear awareness of where the rocket is pointed relative to your body position may help you time your deployment activation to your best advantage. (Please remember that in an emergency you may not have the luxury of timing your deployment).
ROCKET PULL DIRECTION V PARACHUTE CONTAINER CONFIGUATION AND PACKING
Harness mounting location of the rocket is complicated by the problem of where to mount the parachute. The parachute should be secure when in flight yet easily extracted from the parachute container when needed. We have long known that the safest location for the parachute container is directly on the chest of the harness. Reports of pilots minimizing serious internal injuries due to the parachute acting as a cushion between the pilot and jagged rocks, barbed wire fences or impact with hard ground are numerous. We also know that the rocket will work most efficiently when the parachute is extracted from the container in the same direction as the rocket is pulling.
To evaluate your systems rocket /container configuration, you may want to do this little test: Please note: this test does require that the parachute be repacked.
Hang in your harness. Have a qualified rigger disconnect the cord from the quick link attaching the rocket to your parachute and replace it with a cord attached to a hundred-pound fish scale. Hold onto a solid object as the rigger does a slow pull on the fish scale the same direction that your rocket is pointing. The rigger should note at what distance from the rocket launch tube the scale reaches maximum force. Continue the slow pull until the bridle is completely stretched out away from the harness.
The Slow Pull test will tell you:
1. If your rocket is pointed in an acceptable direction to allow easy extraction of your parachute.
2. If your parachute was packed in such a way as to allow easy extraction.
3. If your bridle is routed properly.
4. It will aid you in imagining where your rocket is going to pull the parachute in an ideal situation.
Evaluating your findings.
According to common sense, if the maximum force required to extract your parachute is around 25 pounds at any distance from the rocket; you are in good shape. If the force exceeded the following limits, you may want to have your system re-evaluated. Chances are good that using a slightly different packing arrangement can reduce the hard pull.
|Distance from rocket||Maximum acceptable Force using a compressed air rocket with 3000 lbs. psi.||Maximum acceptable Force using a pyrotechnic rocket|
|1||40 lbs.?||25 lbs.?|
|2||35 lbs.?||35 lbs.?|
|3||30 lbs.?||40 lbs.?|
|4||25 lbs.?||45 lbs.?|
(These are GUESSES BRS was not able to give us the actual numbers, they did agree that these numbers were conservative)
Remember that this slow pull test shows you the worse case scenario for direct pull. In an actual firing, the rocket has the mass and momentum to aid in over coming resistance. Imagine that you are walking your 100-lb Doberman and he sees a fire hydrant ahead. As he tries to slowly pull toward that fire hydrant, you can easily hold him. Now imagine he sees a sexy poodle and darts off to the end of his 8-foot leash. 100 lbs. of dog yanking on you all at one time may really set you off balance.
The ease of parachute extraction must be weighted against the increased possibility of accidental deployments due to easy extractions. It is my belief that the use of Velcro on Ballistically deployed parachute containers may soon be replaced with better designs.
CARE AND MAINTENANCE OF YOUR BALLISTIC SYSTEM
As we learn more about the actual use of ballistic systems during emergency situations, it is obvious that our standard operating procedures must be modified accordingly. Your rocket inspection and maintenance schedule, as per the manufacturers recommendations, needs to be strictly adhered to. As developments take place, you need to keep informed by contacting the manufacturer or reading this magazine.
Specific potential problems to look for in your system include:
Bent, broken cracked or corroded launch tubes.
Worn or frayed handles
Special Care should be given to your system in these areas:
Keep your rocket-parachute harness out of the dirt.
Handle your system like it is a loaded gun,
Do not let children around your ballistic system, especially when the safety is not on.
Be sure to release your safety before each flight and then put on your safety after landing. Do not walk around with your rocket safety off.
Hang gliding is a high-risk sport. Parachute systems do not always work. Sometimes a potential problem with a system will not emerge for many years. When things do emerge dont be lazy in getting your system checked out. We can try to reduce the risk by keeping aware of any design changes or system improvements.
Learn from other pilots experiences. Each time you hear of an accident imagine yourself in that position and mentally prepare your plans of action. Remember, next time it could be you!
Note: I would really like to commend the pilots described in this article for their incredible presence of mind when dealing with "un-perfect" situations. Lets hope we can all learn from them.
Side note: When Second Chantz closed its doors in late January of this year, many pilots were left with ballistic systems not supported by a manufacturer. At this time an alternate source for support is not known.