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  1. #1

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    Another Newbie with Questions

    A few months back I purchased my very first, used skydiver and have recently made about a half-dozen flights with him. I'm not sure of the make/model...has a parafoil chute, body is plans built from ply, balsa and a Williams Bros pilot bust, and has (3) full size servos - arms + chute release.

    It deploys from the aircraft and deploys the chute after freefall just fine. However, though I have left/right and (some) up/down control, the diver does not fly forward at all: drops straight down from the release point. I don't know if it's the steering lines (I believe I have the them rigged correctly per the plans) or if it's a weight vs chute area problem or what.

    Looking for any help/advice in this matter.

    THANKS!!!!!

  2. #2
    goldenknight1's Avatar
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    RE: Another Newbie with Questions

    shy2sail it sounds like you might have to much donw incidence in lead edge of canopy hang your jumper up side down and see how far down the front of canopy is below the trailling edge. you should only have about a 10 to 12 degrees in the front any more that that and chute will fly but the lead edge is too far down the chute will only fly straight down no forward flite at all. Try sfortening your rear risers on jumper about a quarter inch (1/4) and jump him again if this makes chute want to go forward try shortening it a little bit more. You have not said what the weight is on your jumper but most of the jumpers here are around 1 3/4 to 2 pounds in weight , I hope this will help get a better flite out of your jumper.


    Bob

  3. #3

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    RE: Another Newbie with Questions

    Thanks Bob! I think my jumper weighs in at about 1lb 9oz...I'll weigh him again tonite to verify. I'll also check to see leading edge vs trailing edge incidence. If I recall, if I hang him upside down, the chute trailing edge hangs just below the leading edge (when his arms are in a neutral position), though I'm not sure what angle exactly.

    When you mention rear risers...what lines exactly are you referring to? Are these the lines from his hands to the chute (control lines)? Or are they something else? Sorry...I'm VERY new to this!

    Thanks!!!

    Steve

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    RE: Another Newbie with Questions

    Hi Steve,

    It's always nice to have another skydiver join us.
    Check the incidence as Bob described, mine are around 18-20 deg.
    Also the steering lines could be too tight, causing it to fly with the brakes on.
    My jumper with a 28" X 60" chute weighs right at 4 lbs. you may need to add more weight and that also depends on the wind conditions.

    I have a smaller jumper with a 17" X 38" chute and it weighs in at 1lb. 9oz.

    A jumper with a chute around 24" X 48" would most likely need to weigh 2.5 to 3 lbs.

    Just my two cents worth,

    Gary V

  5. #5

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    RE: Another Newbie with Questions

    Thanks for all the replies and welcomes!

    Here are the stats from my jumper:

    Jumper height: 13 1/2"
    Jumper Weight: 1lb 2oz (including parachute...1lb 0oz just jumper)

    Chute dimensions (top horizontal surface): 33 1/2" x 19"

    As far as the indicence...this is when I hang him upside down, the trailing edge of the chute should be 10-12 deg (per Bob) or 18-20 deg (per Gary) LOWER than the leading edge, correct?

  6. #6

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    RE: Another Newbie with Questions

    weight seems right for the size chute - Might want to loosen the control / steering lines a little , You may be braking all the time and that will stop forward motion, Poss to add a couple ounce weight and see if needs more weight , some of the changes should make a differance and adjust from there
    Good Luck and welcome to our Mini Sky diving world
    Don Mowery rcskyjumper.com

  7. #7

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    RE: Another Newbie with Questions

    MANY MANY THANKS!!

    I'll give the steering line adjustments a try and may play with the weight a bit. I made some provisions on the base of his feet to add/remove weights to see if that made any difference.

    Thanks again, and I'll let you know what I come up with

    Steve

  8. #8
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    RE: Another Newbie with Questions

    jumper up to as close as two pounds as you can get and with the other advice you have received from other jumpers you should have a marked improvement on the way your jumpers fly

  9. #9

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    RE: Another Newbie with Questions

    Thanks Bob! I had initially thought the jumper was too heavy for the parachute size, making it fall straight down...I obviously have a lot to learn about these things!

    I'll give it all a try and will let you know how it goes!

    Thanks again-

    Steve

  10. #10

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    RE: Another Newbie with Questions

    Just another random thought and possibly evidence that my jumper may be too light for the size parachute I'm using. I took a look at the large jumpers from 'rcskydiving.com' and did some basic calculations to see if there was a ratio of canopy size to diver weight. I'm sure this is best calculated with parafoil area, but they don't list that in their info (only span) so I'm going on the assumption that parachutes of this type have similar cord to span ratios so that as far as generic canopy size to jumper weight ratio is concerned, span will do.

    Anyhow, for their "ultimate" jumper with the standard parachute, the ratio is 1.02" of canpoy span per oz of jumper weight. For their "Ultimate Hangtime" jumper with 'oversized' parachute, the ratio is 1.31" of canopy span per oz of jumper weight. Now for my system it comes out to 2.09" of canpoy span per oz of jumper which is significantly lighter than ever their largest "oversized" parachute to jumper combination. I'm going to try to add weight to bring the ratio closer to the 1.3"/oz as well as the other steering line/riser suggestions to see where that takes me.

    NOW, all this being said...for those of you that build these things from scratch...is there an ideal jumper weight per canopy area that I should be shooting for?

    Thanks again for all the help!!

    Steve

  11. #11
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    RE: Another Newbie with Questions

    ve if you would like to go to go to RCSkydiver in the CORKS rally dvd bolg he has a good dvd showing jumpers in action and some times you can get more information out of pictures than trying to set up jumper by yourself. Some real good scene in there and Jim will be glad to send you DVD at a ral cheap cost.


    Bob

  12. #12
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    RE: Another Newbie with Questions

    You are on the right track with thinking of weight to square inches of chute. The only problem with a chute verses a stiff winged airplane is there are a million other variables with soft parachute airfoils.

    The best answer I have seen given here is loosen the steering lines at first. Maybe add some weight to the diver and see if it helps.

    There are alot of parachutes that fly good and if you take there specifications they are all different. Yes I think our Hangtime Ultimate and Micro Chutes fly awesome at the ratios you stated, but that doesn't mean yours will even if you get the same ratio. Square inches verses weight (wing loading) is how we came up with our Micro and Hangtime, they are both identical. Weight of the diver, wing area, angle of attack, and airfoil all go hand in hand to make or break a good flying diver. Getting the right combination for your diver is all you need, no matter what someone else is using. Some of use sew up the back of our chutes and some don't, this makes a huge differance in forward speed.

    Best thing to do is try one thing at a time adjusting on your chute, try to jump in the same mph winds every jump. Jump 2 or 3 times and then adjust more or try adjusting something else. This technique is used by all of us to get what we like in our chutes.

  13. #13

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    RE: Another Newbie with Questions

    Thanks all. It's pretty funny...after my last post I did a web search and came across one of your posts, Dave, on the very same subject back in 2004!

    It does seem like it's very much a "per chute design/per jumper" type of thing as far as what works and what doesn't. Like you said back in 2004, if there was a "Perfect Chute" we'd all be using them! Well, I think I've done enough digging and it's time to take my 'cyphering' to the field testing/experimentation mode!

    Thank you all for every and all input!!!!!!

  14. #14
    goldenknight1's Avatar
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    RE: Another Newbie with Questions

    Steve; Rdge pilot gave you a very good information on chutes there are as many varibles to chutes that a 1/2 inch can make a world of differents in the way a chute will fly , Dave has been at this as long as I have and sometimes it really gets mind boggaling. And what he sent you is the thing that all of us sent e-mails about. Take it one step at a time and write everything you change so that you do not lose tract of what you have done so far. Here is hoping that you will have excellent results with your endeavers


    Bob [8D][8D]

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    RE: Another Newbie with Questions

    Edge Pilot and Golden Knight are right One step at a time and make notes , we all have been there and it takes a little time as I even now am working on a new style chute and still working some wrinkles our along with a new Jumper - so I have double trouble but one step at a time and it will get done. Once it is ste up you will have more fun than you know with it
    Any time we can help just got on here and ask
    Don Mowery rcskyjumper.com

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    RE: Another Newbie with Questions

    Many, many thanks for all of the great response from all!

    I did get a chance to take a look at my setup last night, and noticed that when I have the jumper's arms in the neutral up/down position, the parachute hangs exactly level - leading edge the same as the trailing edge...this could definately be part of my problem.

    If I can get a clubmate to fly my jump plane, I'm planning on making some adjustments (one at a time!) and getting some jumps in later this afternoon.

    Thanks again!

    Steve

  17. #17
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    RE: Another Newbie with Questions

    Good luck Steve and be sure to let us know how things work out






    Bob[8D][8D]

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    RE: Another Newbie with Questions

    Well I was all set to do some drops and testing this weeknd, but my jump plane pilot had other work to do...and then I went and wrecked my jump plane while testing prop/motor combinations. It's not a total loss...broken firewall and bent prop shaft, but it will put me back a bit in testing.

    For fun here's a photo of my jumper ready for deployment secured to the bottom of my father's .40 trainer (which he's made the majority of his jumps from). Unfortunately, this plane and pilot (dad) live about 500 miles away, so this doesn't happen too often.
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  19. #19

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    RE: Another Newbie with Questions

    I was FINALLY able to test drop my diver after making a few changes, and unfortunately experienced the same results. I loosened the steering lines and added some lead to bring him up to about 1 7/8 lbs. Still had no forward flight characteristics whatsoever - just dropped straight down (or whatever direction the wind was blowin). I did have left/right control as I could see him turning with the radio stick movements, but up/down did not seem to make a difference whatsoever. I'm not sure if it's my techique, or if there still are setup problems with this jumper.

    To make matters worse, a strong gust of wind took him out of the flying field area and planted him about 70' up a tree (where he's still hanging). If I can get mother nature's cooperation in getting him down, I'd like to figure out why he doesn't seem to be flying right.

    Any help or suggestions certainly welcome!!

  20. #20
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    RE: Another Newbie with Questions

    Bob again Steve how many lines do you have giong down from chute if you have only four on each rib the number two line will be your center of gravity when you hang cute upside down use a protracter on the number two line put protracter cente mark on number two line and theturn it until the straight edge is even with chute read how mant degrees is on he protracter on rhe back side of chute it should read between 12 to 17 degrees hope this might help you some more




    Bob

  21. #21

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    RE: Another Newbie with Questions

    Hi

    Do you know what type of material the chute is made of. If it has too much porosity it will also just fall from the sky.

    Riaan

  22. #22

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    RE: Another Newbie with Questions

    Protracter! ... I think your chute needs adjustment in the back... let it out past 17degrees go to like 20plus and then work backwords... be careful beyond 20 he might be in lots of trees if you can't control him well..

    ... keep trying don't give in to the tree monsters!

    Ucak

  23. #23

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    RE: Another Newbie with Questions

    Thanks again all! As of last check he was still in suspended animation mid-flight...though I did recover his chute pack which decided it was done with the hanging in a tree stuff

    My gut says exactly what the last posts say - there is an AoA problem with the parachute causing him to have the 'brakes' on full time. That adjustment will require re-rigging new riser lines as all of the risers are cut to length and CA'd in place. What type of line to most folks use for riser/steering rigging?

    THANKS!

    Steve

  24. #24
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    RE: Another Newbie with Questions

    Steve I am now using 30 pound ashaway woven dacrin line from into the wind kite store a roll 500 fett long will cost you $8.95 and they have it in 50 pound line also for12.00 dollars this is a very good strong and flexible line. go to intothewind.com and take a look.






    Bob

  25. #25

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    RE: Another Newbie with Questions

    Thank you Bob!


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