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Author Topic: E3 tips  (Read 2930 times)
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Ca Ike
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« on: October 11, 2010, 05:36 PM »

Having recently added an E3 to my bag to replace my Quantum I had noticed a lot of the issues in flight people were mentioning.  Here's a few things from a post I did on Prisms board that new and current E3 owners here might like.    Here is a pic showing a cap from a bic pen in the gap (for reference) between the spine and center T on my E3.




This is what I did to fix it. I used 2 layers of 3M FP-301 heat shrink tubing.  There is still some play in the center T but its much better.




Here is a nice little way I have of storing my batten rods so I don't lose them. I'm sure someone beat me to this idea though Tongue

 


And last but not least here is my E3 in all its glory Smiley



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Ca Ike
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« Reply #1 on: October 11, 2010, 05:39 PM »

Here's my take on the flight issues that have been mentioned by a lot of people and my results after a lot of testing time.

After testing all the bridle mods posted and even trying a few of my own I have come to the conclusion that the problem with the E3 is not the bridle but the winglets.  Now before you say I'm all wet the issue is not in the design of the sail.  To understand where I'm coming from you must understand what the winglet actually dose.

Winglet purpose:

The primary purpose of a winglet in a high aspect ratio kite is to reduce the tendency to stall (oversteer) in the wingtip and add stability in a turn. The secondary effect of a winglet is that it adds a bit of sail area and can increase drive and stability in straight flight

Essentially what the winglet does is akin to the flaps on an airplane.  It helps control the washout ,by the use of a batten rod, in the wingtip therefore controlling the stall potential.  Washout is how much the wing tip twists under pressure.  In straight flight there is no twist and as you turn the wingtip sail twists presenting less sail to the wind and stalling letting the rest of the kite come around (hence creating the turn).

Batten Rod
The batten rod is what actually controls the rate and amount of washout the winglet is allowed.  This is a fine balancing act.  Too little batten tension and you get too much washout resulting in oversteer.  Too much and you get understeer or a nice wide turn radius and in straight flight the winglet becomes a flap adding drag and slowing the kite and increasing the wind speed needed to get the desired amount of drive.

There are 3 ways to adjust the batten.  Length. angle and flexibility.  THey all do the same thing in that they adjust the tension and amount of movement the batten rod allows.  I won't go into the details on this as it gets into a bunch of physics explanations thats not really needed here.


Effect on the E3

As I found, the tension along the TE on my E3 was really uneven.  Flight in anything under 15 Mph winds was very slugish and under 7-8 mph nearly impossible to keep aloft.  In 3-5 mph winds my E3 would in effect fly backwards, have a tendency to sit nose low in the front flip position and fly more nose forward in normal flight(heavier). Turtles or backflips are weak and won't lock in due to the wingtip profile being too flat.  Fades will be unstable tending to wobble along the spine axis or end up in a nose dive due to the same wobble.


The Fix

If you have any of the flight characteristics I mentioned above try this fix I did before you do any bridle mods.  Slide the lower LE out just enough to be able to get the spreader fitting and batten fitting off.  Put the spreader fitting on first, then the batten fitting.  What this does is lower the tension in the winglet allowing more washout in turns. straightens the TE profile between the standoff and wingtip and reduces drag in normal flight.  Here are a few pics after I did the mod.







Before this mod I wasn't happy with how my E3 flew.  Now its very responsive.  Still very stable/precise in normal flight and has that tight spin turn that we have become accustomed to on Prism kites.  It is also very usable in 3-4 mph winds now where it wouldn't even get off the ground before however you still need at least 5-6 mph to trick effectively.  The only bridle mod I would add now is a knot every inch along the leader from the prussic knot to add a variable input sensitivity adjustment (more radical edge).  I still plan to test out a cross active bridle mod now that I have solved my flight issues and will post up the mod and results for those that would like to try it for themselves.
« Last Edit: October 11, 2010, 05:41 PM by Ca Ike » Logged
RobB
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« Reply #2 on: October 12, 2010, 05:00 AM »

Maybe this post is on the wrong board ? I looked in the dual line board and kite building & repair for it first. I don't know how many people on this forum are still flying the E3, if they tried one at all. I've been messing with mine alot as a diversion from learning tricks. When I get frustrated learning tricks, I take a break and work on something else. So, I've been tuning and testing my E3, as well.
I'm anxious to try this wing tip mod to see if it gets the kite closer to what I want & expect from it. I'm sure the hundreds of years of collective experience here will provide quick answers to some of the tuning questions.

~Rob.
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indigo_wolf
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« Reply #3 on: October 12, 2010, 09:58 AM »

Are you essentially transposing the order of the batten and spreader fitting on the LLE?

FWIW: In your first pic, it looks like the batten fitting is starting to pucker the LE pocket cutout.  This might have been something the lower APA fitting prevented the batten fitting from doing in the stock setup due to pressure from the lower spreader. I can see where this might cause problems in the future or possible even be a point of failure.  might consider a heat shrink ring between the battten fitting  and the upper portion of the cutout to ease stress.

ATB,
Sam
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Ca Ike
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« Reply #4 on: October 12, 2010, 02:32 PM »

Are you essentially transposing the order of the batten and spreader fitting on the LLE?

FWIW: In your first pic, it looks like the batten fitting is starting to pucker the LE pocket cutout.  This might have been something the lower APA fitting prevented the batten fitting from doing in the stock setup due to pressure from the lower spreader. I can see where this might cause problems in the future or possible even be a point of failure.  might consider a heat shrink ring between the battten fitting  and the upper portion of the cutout to ease stress.

ATB,
Sam

Yes I'm basically transposing the fitting order.  These pics were taken just after I did the mod in the field and I didn't have anything to use as a stop.  For a temporary stop I took a 4 inch piece of electrical tape, cut it in half along the length and wrapped that around the LE.  Later I may switch to using yoyo stops as a batten fitting since I can tighten those on with zip ties to hold them in place and avoid using a C clip and glue or a heat shrink stop.
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ghfisanotti
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« Reply #5 on: October 13, 2010, 04:29 AM »

Would this be same as shortening the baten a few milimeters? I always thought that this baten added too much tension to the wingtip, but never thought it would make such an influence on the kite performance. I will try making a shorter baten to see if I realize the same improvement you did.
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Ca Ike
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« Reply #6 on: October 13, 2010, 09:48 AM »

That was my next step to test.  I had 2 reasons to move the fitting though.  One was to relieve some tension and the second to align it perpendicular to the TE.  Battens in pretty much all types of wings are always set to be perpendicular to the trailing edge not the leading edge as the E3 originally was before I moved it.
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ghfisanotti
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« Reply #7 on: October 13, 2010, 05:05 PM »

Interesting concept that of perpendicularity, but I'm a little bit concerned about the pressure the baten connector seems to be applying on the wing cutout in your picture, I think I'll try a shorter baten first.
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Ca Ike
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« Reply #8 on: October 13, 2010, 10:30 PM »

I have a stop above the batten fitting now but when I first did it and took the pics I didn't have anything to make a stop out of.  If you do shorten the batten rod let me know how that works out.
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RobB
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« Reply #9 on: October 14, 2010, 04:23 AM »

Hey G...
We were talking about all these E3 mods over on the Prism forum, and your name came up. The question was whether or not you had modified your E3 in any way, and whether your is a 2009 or 2010.
I hope to get my E3 out to try this over the weekend, but we've got a storm coming in, so this weekend might be a blow-out.  Sad
~Rob.
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Ca Ike
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« Reply #10 on: October 14, 2010, 10:22 PM »

Good luck with that Rob. Winds here were strange today Lips sealed  1-9 mph variable and changing up to 180 degrees direction.  Made for some interesting flying.  Backflip n lazyin with wind from the north and having the kite spin overhead as it followed the wind change.  Wish I had a video cam for times like that.  Even got flying in a dust devil and did some 360 passes lol.
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ghfisanotti
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« Reply #11 on: October 17, 2010, 05:32 PM »


We were talking about all these E3 mods over on the Prism forum, and your name came up. The question was whether or not you had modified your E3 in any way, and whether your is a 2009 or 2010.


My E3 is a 2009 edition, I've applied the bridle mods suggested by various pilots here and in the Prism forum, basically shortening the lower outhaul and increasing the length of the inhaul, appart of that, I only added some more weight to the end of the spine. Here is a pic with my present bridle measurements:

https://docs.google.com/leaf?id=0BwyuC0Tsy3NDOTYzZTI1ZmUtNjY5Ni00MTlmLTkzZmItMWE5NDU0NjRiNjdl&hl=en

I'll leave to you the units conversion  Wink
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Ca Ike
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« Reply #12 on: October 17, 2010, 05:54 PM »

Interesting thing for me was that I tried all the mods for the bridle everyone suggested.  However I still found the kite, even though it turned better, still very sluggish in anything less than 10 mph.  When I really looked at my E3 and noticed how uneven the tension in the TE was, how flat the profile was at the wingtips was and how there was a bit of forward camber to the winglets, I got to thinking about the hang glider ultralights I was seeing and how they would tighten winglets to slow them down some.  Nice thing about the winglet batten mod is it negates the need for modding the bridle and you can use the factory measurements.  Of course I still plan to see what an active bridle mod will do Tongue
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Ca Ike
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« Reply #13 on: October 25, 2010, 07:40 PM »

Well now that I have a good amount of time on my E3 experimenting I'm going to try and sum up everything I have tested.  What started all the tweaking from everything I have read is the fact that the E3 doesn't have the familiar prism feel.  IT doesn't spin in turns and can be rather sluggish.  Doesn't have a strong turtle and fades can be unstable.

First off all the mods tried work and pretty much do the same thing.  The bridle mods as well as my batten mod both change how the kite wingtip performs in a turn.  The bridle mods pull the wingtip deeper in the turn making the tip stall sooner resulting in a tighter spin. My batten mod takes some tension out of the winglet letting the wingtip twist more also causing it to stall sooner.

However, thanks to a few different people mentioning the standoffs, I can say all the mods tested aren't all that necessary.  The E3 is more dependant on standoff position than anything else and this has the biggest effect on performance. 

My E3 set up is now completely stock.  I have removed all bridle mods and reverted my batten fittings back to stock.  The only adjustment I have in my set up now is I no longer use the first 2 light wind standoff settings.  For tricking purposes set the standoffs in the 3rd or 4th hole(high wind) and this will give very tight spin turns and flatter axel based tricks(depending on amount of ballast).  For precision and tracking use holes 1 or 2.  Also for lighter winds shortening the battens by 1/2 inch will give the same effect as moving the batten fitting.  I now have 2 batten sets. Stock for high wind and a short set for light wind.  I am testing a stock length 1.5mm batten set to see how the extra flexibility does.

The E3 is also highly dependent on ballast.  Rob has the best set up for ballast using the Q-Pro weight set and center T.  The sweet spot for ballast adjustment on the E3 is from 4 inches below the center T to 2 inches above.  Ballast amount depends on wind. For light winds(4-8 mph) 10 g works well.  In high wind (9-15 mph) 16g seems to be the best.  For all around 13-14g is a good weight.  if you changed to a p100 spine or similar then 13g would be my pick for light wind ballast.

The E3 also seems to like a heavier bridle setting which I think is more due to the very short turbo leg Mark designed into the bridle.  For me adding 3/4 inch to the turbo leg works well to give just a bit more responsiveness and for really radical response a knot at 10 cm from the prussic knot on the leader is what I use.  I also had to move the knot on the sail tensioners by 1/4 inch to take the slack out of my LE's

No matter what you do to your E3 the trick sweet spot will always be 8-12 mph due to the weight of the kite itself.  It will fly in as low as 3mph without ballast but your better off with a Zeph, Q-pro sul or 4d down that low.
« Last Edit: October 25, 2010, 07:47 PM by Ca Ike » Logged
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