This is not advice, but a posting for historical reasons:

Selecting a BASE Canopy

From: ftr@sam.neosoft.com (Walt Appel)
Newsgroups: rec.skydiving
Subject: BASE Article #4 - Selecting a BASE Canopy
Date: Sun, 30 Apr 1995 22:58:16 UNDEFINED

This is the fourth in a series of articles that I am posting about BASE jumping. It gives general tips on what to look for in a ramair parachute intended for use on BASE jumps. I will be devoting the next several articles to canopies. Future articles will include more discussion on equipment, techniques, and general info. I will also discuss sources for gear and information.

Feel free to e-mail me, but don't ask me to recommend specific sites. I will not recommend specific sites, nor do I recommend BASE jumping. BASE, even though it has evolved a great deal over the past few years, is still somewhat experimental and I consider it to be an extremely dangerous activity. I am posting these articles because the lessons that have been learned about BASE have cost us dearly. I do not want to see anyone hurt or killed because they were unknowingly re-inventing the sport.

In case, you're wondering about my background in BASE, I have made 55 BASE jumps, mostly freefalls from under 500 ft, from a variety of sites. I make and sell BASE accessories, e.g., pilot chutes, bridles, mesh sliders, etc., and I have been on the Bridge Day staff for the past few years.

Disclaimer: I am not now, nor will I ever be, the final word on BASE jumping. Nobody is the ultimate authority.

BASE is an extremely dangerous activity. In my opinion, the best way to reduce your chances of injury or death is to talk with as many experienced BASE jumpers as you can, learn as much as possible, *think* about it, and jump in a way that makes sense to you. This article is written from one person's point of view (mine) and you'd be nuts to consider it the best or only point of view. There is a lot more to BASE than any series of articles can present. Use the information only as a starting point.

Selecting a BASE Canopy
What if you were independently wealthy and could buy an entire arsenal of canopies for BASE jumping, selecting the perfect canopy for each jump? Surprisingly, you'd find that one or two canopies would handle just about any BASE jump you'd want to make. Rounds and Ram-airs are both used for BASE jumping, but the overwhelming majority of BASE jumps are done using ram-air parachutes. Ram-airs are particularly well suited because of the high degree of controllability and the ability to adjust their opening speed from very fast (e.g., slider removed, free-packed, large BASE pilot chute) to slow (e.g., sail slider up, small pilot chute, deployment bag) to in-between (e.g., mesh slider up, medium-sized BASE pilot chute).

In my experience, rounds are generally good for water jumps-- especially water jumps from cliffs--because it saves your ram-air from getting wet and because if you do have a 180 degree off-heading opening and have a wall-strike, the forward speed will be quite low and the canopy will likely stay inflated.

Ram-air Canopies
The ram-air canopies considered to be well-suited for BASE jumping are *not* the kind of low bulk, low weight, extremely high performance parachutes that most skydivers prefer. Does that mean that you won't be able to safely BASE jump your skydiving canopy? Not necessarily, but your odds of getting hurt under a high performance canopy are definitely higher. The reasons are that high performance parachutes generally do not give the consistently on-heading openings that are required for BASE jumping, and their landing speeds are generally too fast for landing in a tight area containing trees, rocks, and other things that can hurt you. While RW canopies tend to be poor choices for BASE, CRW canopies can be excellent choices. CRW jumpers need a canopy that opens on-heading and quickly at low airspeed, characteristics that are also required for BASE jumping.

A BASE canopy needs to open quickly and on heading, have the ability to fly slowly and land softly, and be able to withstand rough treatment. Experience has shown that the best BASE canopies are seven cells with the following features:

# A low aspect ratio,
# Made of non-zero-porosity fabric,
# Dacron or nylon (not Spectra) suspension lines,
# A very strong reinforcement scheme at the bridle attachment point(s) and all suspension line attachment points,
# Very durable construction,
# Surface area that is large enough to give soft landings even in deep-brakes approaches.
Aspect ratio refers to the distance from one end of the leading edge of a ram-air canopy to the other (the span) divided by the distance from the leading edge to the trailing edge (the chord). When referring to high-aspect-ratio canopies, I'm referring to canopies with an aspect ratio of 2.5 to 1 or higher. Low aspect ratio means somewhere around 2.0 to 1. A low aspect ratio gives a canopy more consistently on-heading openings and the capability of flying slowly without the likelihood of a sudden stall. They are well suited for landing in tight areas.

Zero porosity fabric makes an excellent skydiving canopy, but is not widely regarded as being acceptable for BASE canopies. There has been some experimentation, but the results have not been promising. The problems are with lack of sufficient controllabilty during packing and lack of consistently on-heading openings.

Dacron or nylon suspension lines are preferred because of their well-established record of reliability and because they stretch more than Spectra. Their elasticity enables them to partially absorb the high opening-shock loads encountered in slider down openings. Spectra, which stretches very little, transmits more of the canopy's opening shock to the jumpers body. Strong reinforcement also helps the canopy to withstand higher opening-shock loads.

Durability is a real plus in a BASE canopy because of the inherently hard use encountered in BASE jumping. Landing areas are often in areas containing all sorts of things that can poke holes into a canopy or cause abrasions.

Round Canopies
A round can be a real treat on a BASE jump, but I'm not inclined to land one on any hard surface. I limit my use of rounds to intentional water jumps. The best round canopies are modern, F-111 skydiving reserve canopies--they are light, low bulk, dry relatively fast, and have acceptable (although *not* fast) opening performance.

Examples
I'll discuss specific canopies in future articles. For now, here's a few examples of *skydiving* canopies that perform well on BASE jumps:

# The Super Raven (Precision Aerodynamics) - This is my personal favorite. It has a 2.26-1 aspect ratio, which is a little bit higher than ideal, but is well-built, gives consistently on- heading fast openings. I've heard a couple of jumpers say that the old Ravens, i.e., non-Super Ravens, are better for BASE. That is absolute bullshit. I currently own and jump both, and can flatly state that the Super Raven is a better built canopy.

# The CRW Pursuit (Para-Flite) - I have not personally jumped this canopy, but I've seen it BASE jumped and was quite impressed with the opening speed and on-heading performance. The aspect ratio is is under 2 to 1 and it is built to last. The recommendation that I have heard from a BASE jumping Pursuit owner is to use a CRW Pursuit with a conventional (non-retracting) pilot chute a bridle setup.

# Phantom (National), K-series (Pioneer), SAC (GQ Security) - These are examples of round canopies that are good choices for BASE jumping. Actually, nearly any round reserve is a good choice, but these are good because they are made of F-111, which dries faster, and are relatively small diameter, which enables them to inflate more quickly than larger rounds.

Bear in mind that nearly every canopy you can think of, from Para- Commanders to the postage-stamp-sized ZP hot rods, has been BASE jumped successfully. The above canopies are *examples* of canopies that are well-suited for BASE--there are *many* more, including three canopies that were designed specifically for BASE jumping. I'll discuss these canopies in future articles.