cobaltdan

if you dump in a track, no problem if you dump in a knees bent arc position: possible problem. btw regardless of pilot chute size, my rec. is to always dump in a track...check archives for more... sincerely, dan Daniel Preston atairaerodynamics.com (sport) atairaerospace.com (military)

daniel preston atair aerodynamics 499 van brunt street brooklyn ny 11231 usa 718-923-1709 ph 718-923-1733 fx www.extremefly.com Daniel Preston atairaerodynamics.com (sport) atairaerospace.com (military)

Wm: out of curiosity what were the specifics: i.e. what canopies main and reserve, what kind of spin (were you flat on your back and spiraling or were you also line twisting while spiraling), how many revolutions per second, what was your wing loadings? sincerely, dan Daniel Preston atairaerodynamics.com (sport) atairaerospace.com (military)

a skysurfer was one of the first people on our team a few years back. from memory he jumped a cobalt 120 loaded about 1.8 and his standing deployment was at about 140mph. sincerely, dan Daniel Preston atairaerodynamics.com (sport) atairaerospace.com (military)

cobalts are very soft opening canopies and are unique in that over a certain range they will open softer at higher speeds. we routinely demonstrate deployments at speeds that would surely injure on competing canopies. see our web site for video of 180mph head down deployments, 535# exit weight deployments on a cobalt 120, and up to 1000# @ 184mph deployment on our cobalt 350, all live jumped. i we have logged test jumps with deployments up to just under 260 mph) it is rare for a cobalt to open hard. in those instances it is usually because it is not being used corectly, is out of spec from line or tape shrinkage, or a fluke. if someone reports a condition where a cobalt is opening hard. we first have a discusion and advise on the proper set-up and use the canopy (also posted on the faq page of our web site), i.e. what size pilot chute, the effect of rear risers during deployments etc... we further explain that if this does not solve the problem to immediately send the canopy back for testing. we strongly stand behind our products. i just looked up our stats, we computerized 2 years ago, in that time less than 1/4 of 1% of the canopies we manufactured had logged comments about their openings. a much smaller percentage actually had issue. and all situations were resolved. but you know the old saying "100 at-a-boys = 1-uh oh". sincerely, dan Daniel Preston atairaerodynamics.com (sport) atairaerospace.com (military)

"cobaltdan claims: "but basically where you 'hang' under the canopy is a function of the airfoil chosen and its pressure distribution." groundzero replies: the point where one "hangs" is determined by the designers lineset. Angles determined by the b and d cascades and their insertion point in the a and c lines will determine where the mass will be located under the airfoil, whether it be a "pd" airfoil, an atair airfoil or any other airfoil. must run to play! Chris xox " chris: your statement is incorrect. if you draw a vertical line from the jumper up to the canopy you will see that where the jumper is suspended under that canopy is not determined by your line lengths and cascades as you refer. where that line intersects your canopy is dependent on the angle of attack the canopy flies with. this is influenced within a small range by the geometry of your lines, but mainly the pressure distribution of your chosen airfoil. different airfoils with identical line trims can fly at different angles of attack and consequently where you "hang" under each canopy is different. for clarity i will resate: for a given airfoil there is a limited range of angle of attack where the canopy will have desirable performance. chosing an airfoil with a different pressure distribution allows the designer to change where a jumper is loaded under the canopy with a similar range of angle of attack. i.e. the difference between a fore loaded canopy (any canopy with a pd airfoil: xaos, fx, vx, stilletto, etc) and a center loaded canopy: cobalt. sincerely, dan Daniel Preston atairaerodynamics.com (sport) atairaerospace.com (military)

white zp is a color... what i mean is that the raw fiber is actually yellowish. to make white courmarin dies, sometimes called brightners are used. these brightners actually absorb uv light and reemit some light in the blue range making the fabric look whiter. this dye does degrade over time and the fabric will return to a yellowish color. the fabric strength is not effected by the color change. sincerely, dan atair aerodynamics Daniel Preston atairaerodynamics.com (sport) atairaerospace.com (military)

point is the way to kill yourself is with a low turn trying to avoid landing downwind. with practice it is not that big a deal. i have and will take a 20mph downwind landing over a low turn and crash any day !!! landing downwind is a little different and you need to be practiced enough to be comfortable performing it for when the need arises. standing up does not mater, slide skid, plf. as long as it is controlled. you do not want to take a high speed landing and touch the ground while vertically decending. (and yes i can stand up a 15mph down winder)...(not all the time...) sincerely, dan Daniel Preston atairaerodynamics.com (sport) atairaerospace.com (military)

manufacturers opinion: the cobalt is slightly slower in foward speed compared to a sabre2 of equal wing loading. turns are slightly faster, but without oversteer. front riser pressure is lighter. glide ratio is higher. openings longer with less force. flare is stronger. packing is easier (non-slipery zp material). in the event of a premature opening at freefall speeds the cobalt is safer. sincerely, dan atair aerodynamics www.extremefly.com Daniel Preston atairaerodynamics.com (sport) atairaerospace.com (military)

sorry for the late reply...been off line this week. we try to enforce a minimum street price on our products. as do many manufacturers. this is done in the best interest of our dealers and our customers. if everyone sells at comparable prices, it proctects our dealers for a minimum mark up and bennifits our customer by providing a large dealer network, with local representation, all vying for your business with support and service. there are many come and go, no-overhead car trunk dealers and mail order houses, that when selling products wholesale, damage product value and eliminates customer service & support, and put local hard working rigging/dealer companies with real overheads out of business. sincerely, dan atair aerodynamics www.extremefly.com and btw many manufacturers do this, and no this is not price fixing. Daniel Preston atairaerodynamics.com (sport) atairaerospace.com (military)

yes the diablo is elliptical. Daniel Preston atairaerodynamics.com (sport) atairaerospace.com (military)

hey richard, i think you misunderstood my post. i call any canopy that does not use the exact same rib in every position an "elliptical". all "tapered" and "semi" canopies are "elliptical". those terms are marketing names and most times do not give any indication of the "degree of taper". they are used to describe whether the canopy is high or low performance. understand that the "degree of taper" or the "ellipticalness" as people like to say (i hate this) is only 1 variable of many in a canopy design and will not give you an indication of performance without knowing all the other variables. i.e. there are straight leading edge canopies with tail tapers that are far more radical than the many high performance dual taper ellipticals... there are begineer canopies with more agressively tapered planforms than the competition swoop machines...etc. i call a duck a duck. from day 1 i have always stated all our canopies are elliptical from student to base to tandem to swoop machines. i have never used terms like semi or tapered in our marketing, because i find it misleading. sincerely, dan Daniel Preston atairaerodynamics.com (sport) atairaerospace.com (military)

"At one point CobaltDan said on here they could have marketed the Cobalt as Semi-elliptical, but chose not to for marketing reasons." more like for educational reasons. marketing wise it would probably have been better for us to play the game and call one cobalt semi tapered and another identical version elliptical. sounds familiar: alpha and space. the alpha and space were identical canopies, the alpha marketed as an elliptical swoop machine to be used at high wingloadings, and the space marketed as a tapered begineers canopy to be used at light loadings. both were very succesfull. when i founded the american division of atair i decided that i did not like the fact that misinformation ruled (elliptical issue, manufacturer mis-sizing of canopies & wingloading charts so under rated no one adheres to) in the industry and decided to simply try to educate. basicallky call elliptical canopies elliptical and try to educate that whether a given design is a student canopy or a pocket rocket is a function of the sum of many design variables, and that the only thing you can assume about a design because it is elliptical is that potentially it is more efficient, nothing more. our first year, people did not want to hear this. there were violent responses telling us we are going to kill people putting beginners on ellipticals. people could not even assymilate the information that we already had a 6 year track record with beginners on our elliptical space canopy. at the time elliptical was so ingrained to everyone as synonomous with high performance and certain negative traits. its very exciting for me as i believe the education level of most jumpers has gone way up over the last 3 years. they have more understanding for the equipment they jump. "Semi-elliptical = marketing term Tapered = Marketing term Elliptical = Any non square canopy. " well put phree. btw there are no "fully" elliptical skydiving canopies. no "true" ellipse planforms. understand that wether a canopy is considered high performance or low performance is again the sum of many design variables. as someone pointed out an extreme canopy such as the vx is actually much closer to square than many "tapered" begineers canopies. sincerely, dan atair aerodynamics www.extremefly.com Daniel Preston atairaerodynamics.com (sport) atairaerospace.com (military)

"right now it seems like the cobalt can be loaded higher than any other non cross braced canopy...is this pattern gonna hold for the Onyx?" yes, in fact this is one of the reasons we designed the onyx. not to make smaller sport canopies, but to make higher wingloaded military canopies. in testing the ability to land a cobalt tapers off at 5:1. the onyx will definately extend that range. sincerely, dan Daniel Preston atairaerodynamics.com (sport) atairaerospace.com (military)

there is a certain amount of play, but basically where you 'hang' under the canopy is a function of the airfoil chosen and its pressure distribution. the fx,vx,xaos and stilletto all use the same airfoil (the "pd" airfoil). how much lift a design produces governs how you set its angle of attack. the amount of lift a design generates is governed by the airfoil and planform efficiency and drag (or lack there of, i.e. reducing spanwise distortion). planform and airfoil making the most difference. must run to a meeting.... sincerely, dan Daniel Preston atairaerodynamics.com (sport) atairaerospace.com (military)

"I can use them up high to some extent, but it is very hard to judge the subtleties of timing a flair without the ground as a reference. " true, but you can learn enough up high to give you the skills required for your potential emergency rear riser landing situation. additionally, it will improve your skills to practice mock swoops and landings without using the ground as primary reference...what i mean is that your sence of balance plays a huge part in properly executing swoop landings. it is simply to learn to feel, without any visual reference, at what part of your arc you are at. in high, clear airspace try it with your eyes shut. not sure if i am explaining myself well today...basically restated from an old thread on "balance and canopy control" sincerely, dan as far as landing with one brake set....hmm never really though about that one. i would like to think that i would never open so low as to not to be able to diagnose that problem befor my cutaway deck. i would think that you basically have 2 options at that point: fly carefully in brakes and attempt landing, or cut the brake line and land on rear risers...the correct choice i believe depends on the particular canopy, loading and weather. brake settings differ from design to design, as does low speed flight performance and safety in turbulence. Daniel Preston atairaerodynamics.com (sport) atairaerospace.com (military)

if you are comfortable landing a 120 main, you should be just as comfortable landing a 126 reserve. pd reserves fly just like a spectre canopy. if in doubt the solution is easy. instead of a online debate, just demo the reserve as a main. all you questions will be answered. (and i am a firm believer that the first time you fly your reserve should be under planned conditions).... 2 cents... sincerely, dan Daniel Preston atairaerodynamics.com (sport) atairaerospace.com (military)

i think the attachment will work this time... i know....i can't spell...i will try to post some airfoil pictures this week when i am in the office for explanation. sincerely, dan Daniel Preston atairaerodynamics.com (sport) atairaerospace.com (military)

greg yarbonet is alive, well and works part time for atair aerospace. he is an amazingly nice guy ! (he did not die in any accident) attached is a pic of the V-wing canopy greg and i designed last year. this one is a 95. double skin nose which transitions to a single skin behind the b lines. V shaped ribs form airbeams extending to the tail. the resulting high chamber airfoil have very low volume. it was an experiment to gauge using high chamber wings for base canopies. the canopy was very slow in foward speed and very floaty. flys more like a 200 than a 95... sincerely, dan Daniel Preston atairaerodynamics.com (sport) atairaerospace.com (military)

"Later versions of the Volplane were equipped with sliders. " we have "slider #1" hanging on our wall, signed and dated by greg yarbonet (slider inventor). its pretty cool simply a webing X with d rings in each corner. we also have the original very first canopy to be fitted with a slider, dubbed "bumble bee". i'll see if i can post a pic for anyone interested. sincerely, dan Daniel Preston atairaerodynamics.com (sport) atairaerospace.com (military)

eric butz, brian harrel (and of course me) have jumped the onyx 28 size 95. the onyx 36 (95) is in the sewing que right now and will be completed soon. chuck (if he can deal with such a big kite) is first in line followed by a few of our other pro's. after we complete our testing demo's will be available to qualified jumpers. give me a couple months, we are very busy at present. sincerely, dan Daniel Preston atairaerodynamics.com (sport) atairaerospace.com (military)

something that stuck with me was a bunch of years ago the salesman from 'cool & groovy' came promoting their audiables. the thing had 3 set points, but i didn't like the fact that the last warning was not adjustable (if i remember correct it was set at 1600). their logic was that last chance warning is just that: last chance. you want to have it ingrained into your head that if you hear that siren >go silver< period, no thought process. i understood the logic in this as at the time i was still green and set my dytter's last warning at 2.5k. but in mal situation i had allowed myself to go a few seconds past last warning because i believed i could clear and new i had a small margin of safety built in. so my last warning wasn't really a last warning. i realized that setting your audiables last chance warning high sort of deffeted the purpose..since then i set my dytter different. sincerely, dan Daniel Preston atairaerodynamics.com (sport) atairaerospace.com (military)

the readings are not necessarily off. simply that the digital is far more sensitive than an analog. as quade pointed out our altimeters are not really agl altimeters but rather atmospheric pressure sensors. over the day atmospheric pressure varies a bit and is reflected as fluctuation in your altimeter. analogs are slow with a coarse accuracy displays, therefore you do not notice fluctuations much. digitals are very sensitive with fine accuracy displays and there for you will notice the fluctuation. i have played around with making digital altimeters. i built a prototype about the size of your thumb. idea being you could stick it to your visor for a "heads up" display. works great but i made the prototype 4 digits which is too high resolution and it is annoying to watch the right hand digits count down so fast..... sincerely, dan Daniel Preston atairaerodynamics.com (sport) atairaerospace.com (military)

frank, i have to second chris. when i was still a relatively new jumper i had a situation where i deployed in several twists onder a fairly high loaded wing. as i went into a flat spin i saw the trists and decided i could get out of them in just a few seconds. which i did...just in time to make a 180 and land. i scared the crap out of my team mate and when it sank in, myself. high performance canopies in a spining mal can easily reach freefall speeds ! you should never be thinking time, i.e. just 2 more seconds and i will clear the problem... only altitude: am i above or below my hard deck. if you are below there is no decision to be made: Chop. it should be mindless reaction. no though process beyond am i above or below. thinking, analyzing, indecision, decision all take time which you do not have. the purpose for a hard deck is to have all of your time consuming thinking on the ground in advance: you hit your hard deck without a 4s canopy = ching-ching and when you get to the ground safely, dont be pissed, be happy, think of it as the best $50 you could spend, and that it is all part of the sport we love. sincerely, dan Daniel Preston atairaerodynamics.com (sport) atairaerospace.com (military)

"let's not focus on "right" or "wrong"" ok....lets just talk flying style stabing brakes to come out of a dive wastes some energy both by generating drag and wasting angular momentum. imo i believe some people prefer negative recovery arc canopies because the learning curve is quicker for those who like snap hooks. on a negative canopy it is easier for some people to transition to fast big air manuevers because placement is not as critical and you just stab out. this type of flying style is not the best on a positive canopy such as the cobalt. on the cobalt i prefer carving hooks. in this way you can control how much altitude you drop during the turn by shifting weight in your harness. shifting weight inboard causes the canopy to recover positively, shifting outboard causes the canopy to recover negatively. it is a different flying style and my personal prefference. in competition you do not get points for aerials, i.e. "going big". you get points for efficiency (distance), consistancy and accuracy. as such i am seeing many competitors change styles focusing on the most efficient hook to swoop, such as i mention above.... give it a try sometime maybe 10 jumps or so and report back. both styles and both types of canopies have proven competitive in competition. sincerely, dan Daniel Preston atairaerodynamics.com (sport) atairaerospace.com (military)