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Old Nov 11, 2011, 06:57 AM
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Ashford. Kent. England
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Factors involved... shape, wing loading, there is also a difference in the wing angles of 10 degrees on the outer panels...
When I rebuild I will keep the angles the same and purely alter the shape.. then I can tell whats making the most difference..
I believe its the combination of both shape and loading.. so will advise for now you build in 3mm depron.. its a lot lighter
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Old Nov 14, 2011, 02:48 PM
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Ashford. Kent. England
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Ive chopped of the delta and added heart shapes as tips.. AUW is 19.25oz ...area is 4.7sqft.. wing loading 4.1ozsqft..
I also added an extra 1" to the tip panels spans
angles at the tips are back to 135 degrees
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Old Nov 15, 2011, 07:53 AM
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Flying trials of the above have shown that the heart shape is the key to good performance.. the new model goes easy even though its a heavy lump..wing loading at 4.12ozsqft AUW 19.375oz with a 1000 3 cell
No comparison to the delta , its far superior..

This has given me a good comparison weight for weight.. this 6mm build is 4.5oz heavier than the 3mm build.. The lighter build will go even slower, it feels lots more floaty, and the power to weight is better so it has that bit better performance..It will though be less tough..

I had a good fly untill a passer by stopped to chat and his dog jumped up and got me in the B****.. which lost me my concentration.. so turn down the volume at the end of the video where both of us are cursing the dog..
.
KFm4 Revolution delta is modded to a Heart shape (6 min 12 sec)
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Old Nov 15, 2011, 10:32 AM
What goes up . . . Damn trees!
Cotswolds, UK.
Joined Sep 2010
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I think 'lost concentration' is a bit of an understatement, Dave.
It looks like the old 2-dog "You distract him and I'll grab the plane" trick.

This is next on my build list after I've finished a Micro Sumo.

Andy.
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Old Nov 15, 2011, 10:51 AM
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Yes.. unfortunately I was chucking it about too close to the ground and I got caught out..
The UC plate and motor mount got ripped off .. with no damage to the main wing and an easy quick glue gun fix.. all done..
The three layer foam build does make for a good strong wing..

Note on this one the 6mm layers were directly laminated, but adhesive was only used on strips around the edges, this saves weight on the glue as it is not covering the whole of the laminated area..

Also note, whist they are well aerobatic they are an easy slow fly, rather than a hairy fly.. and are so good for relaxed flying sessions.. I think that with reduced throws they will make excellent trainers.. later having the ability with increased throws to be very aerobatic indead.. a good one to grow with..from trainer to pro..
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Old Nov 16, 2011, 09:20 AM
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Ive upped the motor on the heart W wing to about 200W , its now using an emax 2215/20 with a 30A esc.. the motor and esc didnt add any extra weight, but 2oz is added with a bigger 1300 battery.. now 4.5ozsqft

KFm4 W wing heart with more power (4 min 24 sec)
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Old Nov 16, 2011, 12:17 PM
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United States, MD, Lexington Park
Joined Jan 2010
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Ok Dave..if you were going to build just one of your different setups here...the heat shape one seems to win..what size would you make it? and what is the diehedral angle of the wings relative to a flat plane? looks like on one of yours there is no diehedral..is that right? KFM-2 or 4? which flies best? I'm going to order some depron in a few weeks and want to make one of these...TIA!

Dan
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Old Nov 17, 2011, 07:19 AM
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Definately go for the heart shape, and not the delta..

The Heart shape in 21-23" long is a good size to get both stability and maneuverability.. smaller and they are less stable, bigger and they go very docile

At the moment I am flying a 21" made from 3mm depron and a 22" from 6mm depron.. both are KFm4 and both go well.. the 3mm build is a lot more of a floater than the 6mm build, as there is a 6 oz weight difference between them.. they have wing loadings of 2.77ozsqft and 4.5ozsqft respectivly
..Ive not tried a KFm2, but it would probably be ok if the weight of the foam is a problem... On aerobatic sport models, I prefer to use KFm4 where the build permits it..

My others were at 15" long KFm4 3mm depron.... very maneuverable but being a lightweight it is not stable enough in the general local breezy conditions..might be ok for indoors
.... then one at 26" long KFm4 6mm depron..with a 3.2ozsqft loading... a bit too docile, nice and easy however...

Despite the wide difference in weight and loading loadings both mid size models fly very similar, although at the slow slow speed the 3mm wins out, being more floaty.. for strength the 6mm is tougher...In wind the extra weight always helps..

Angles... inside angle at the top centre joint of the W is 110 degrees
.. inside angle at each tip joint it is 135 degrees
When the W is resting on a table the tips are raised by about 2.5-3" under each tip...but do go by the angles ..
The elevons have a sweep forward of 30 degrees

For shape the last pics show what I use.. It isnt critical but needs to be close enough... the arcs were all hand drawn for one wing then copied for the other..
On the elevons the arc you will see is not even.. the arc for the surface is wider towards the tips.. again they are hand drawn then copied.. for more control use bigger elevons its a TLAR method..
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Old Nov 17, 2011, 04:37 PM
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United States, MD, Lexington Park
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ok big help Dave..thanks...gonna build one here in a few weeks to try out....thanks!
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Old Nov 22, 2011, 08:31 AM
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Ashford. Kent. England
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As a note my holiday night-kite version is progressing.. see the night-kite thread for more info.. http://www.rcgroups.com/forums/showthread.php?t=987191
There is another distraction for you all.. lol
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Old Nov 24, 2011, 07:28 AM
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Ashford. Kent. England
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latest pic

edit its all been done and flown, and its poor, I was having second thoughts with this one as it went more and more overweight.. and looked too big.. the flying was barely ok .aileron response much too slow.. stabilty too good..not at all what I was wanting.. the rudder much more effective and I put that down to the higher dihedral being used.. but overall it was much like an earlier large area kite, with its poor roll and slow responses...

remembering what ive previously said, bigger is too docile, this is way too big....so next I will make a 20" long version
For some reason the kite version is even more docile and slow than the foam version, its probably down to increased angles on the outer panels making the ailerons less effective
.
Night-kite heart shape 26inch maiden (3 min 41 sec)
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Old Nov 27, 2011, 05:24 AM
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Ashford. Kent. England
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I have already got into modding the big kite..
Ive shortened and narrowed the fuzz proportionally for 20" long.. the tips have been left wide, as it was easiest to remove the sweep forward on the elevons, then simply adjust the next rod on the wing to meet up with the end of the fuzz.. The elevons were then reshaped to fit the new shorter length of hinge rod..

from flying the kite with increased dihedral angles, and the delta with higher angles it is now obvious that the tip angles make a significant difference in the performance..
Basically its much what you would expect.. as you increase the dihedral (by decreasing the angle at the joint) the aileron response lessens and the rudder becomes more effective..
Stability tends to increase, but general flying is not as pleasant..
The original angles of 110 and 135 work well... but I shall have to experiment with flatter tips at some time.. with the kite the joins are hinged, so by adjusting the bracing rod lengths I can try some different angles
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Old Nov 28, 2011, 11:44 AM
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mods done 5.3sqft....AUW 20oz ....3.8ozsqft loading.. overpowered with an almost 2:1 power weight ratio.. diagonal cross bracing top and bottom have it nice and rigid...the rear end was heavy and the big motor and battery are needed to get the COG, which will be starting at about 30%

EDIT...the modded kite is going well,
.COG now at 35% back 7" but still wants to go further back..
.
new wing shape maiden(1).AVI (5 min 37 sec)
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Old Dec 02, 2011, 10:29 AM
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Ashford. Kent. England
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more flying at 35% COG all nice and easy with little to no wind today...a real pleasure..
.
W wing night-kite 2nd session (3 min 57 sec)

.
.now with lights
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Old Dec 16, 2011, 08:30 AM
What could possibly go wrong?
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Market Harborough
Joined Apr 2006
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Indoor flying VTOL

Now here's a thought Dave..

Why not build a VTOL version of your excellent W-Wing. I'm thinking of a plan view exactly (or almost) the same as the side view, both the same as the plan of your foam W-Wing. The front view would be a rectangular cross, no W at all.

In other words, replace the fin/rudder with 2 more panels, one above and one below, extending from the nose to the tail, matching the heart shaped layout. I don't think I could get my head around using elevons in both dimensions, so I'd settle for a definite vertical with rudder panels and a definite horizontal with elevons.

Put the motor right in the middle, with slots for the prop; the battery in front; suitable thin cf bracing. Maybe use KFm4 only in the horizontal plane. As an indoor flyer the whole thing would be like a football and fairly ding-proof.

What could go wrong?



PS like all good ideas, somebody's already thought of it.. Crazy Ball
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Last edited by nickchud; Dec 16, 2011 at 08:47 AM.
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