|Feb 17, 2014, 05:33 AM|
"Fusion", Scratch built, high performance, light lift aerobatic glider
This glider came about by combining attributes from two genres of gliders; DLG's and Ultrabatic gliders.
DLG's (discuss launch gliders) ; and in particular the standard 1.5 meter class are amazing performance machines. They are typically highly engineered machines which can be hand launched to great heights and they have superb sink rates. They make great light lift slope gliders, but they are expensive and have crunchy construction
Ultrabatic gliders are very fun, tough, very aerobatic gliders. Surfimp has done a great job documenting the Ultrabatic slope craze in this link. The Ultrabats are typically made from EPP foam with a laminating film covering...a very rugged combination.
I fly slope at the Bluffs in Long Beach primarily. The wind and the lift is often very light. Recently Zupair has developed a great light lift plank, the Zulu. In particular the Zulu XL has been amazing for both light lift performance and its aerobatic capability. Inspired by Zach's creation I decided to see if I could achieve similar capabilities with a conventional (with tail feathers) glider design.
The Fusion was designed with performance as the number one priority. I wanted a good sink rate to allow flying in the lightest of lift. It looks a lot like a DLG for this reason. In the design I have strived to minimize the wetted surface area in order to optimize the wetted aspect ratio to attain the best gliding performance throughout it's speed range. The wing uses a DLG airfoil and minimal sized pod and tail surfaces. The performance results have been excellent with a superb sink rate.
The flying surfaces are made from epp covered with laminating film. The pod has an epp nose cone. Combined with the light flying weight, this construction makes a very tough bird.
The pleasant surprise with this project is the aerobatic capability especially in light lift. On low rates it can be very docile and is easy to fly. On high rates, with the large ailerons and all flying elevator it is a very capable aerobatic glider, capable of the tightest loops (inside and outside), great inverted performance, and some crazy flipping action.
|Feb 17, 2014, 05:34 AM|
Plans, materials, tools
PLANS... coming soon.
Wing cores; I bought mine from FlyingFoam.com
Boom is made from carbon tubing from KitesandFunthings.com 1 length of P300 or P3X tubing and 1 length of the internal ferruling tubing.
1/8" thick balsa
6mm 1.3# epp
3mil New Stuff laminating film, about 7 feet of the 24" wide is plenty.
5 of 1 meter lengths of .5mm x 3mm carbon ribbon
30 pound test Spyder Wire fishing line, available from Walmart
1/16" music wire
3/32" brass tube .014" wall
3/32" locking collar
1/4" heavy wall plastic tube for wing mount reinforcing
small diameter plastic tube for pull/pull string guides
Two 13 gram metal gear servos for the ailerons, one 180 servo for the elevator, one 9 gram servo for the rudder.
Two 6" servo extension wires, and one 3" servo extension wire
6 channel Rx
700 mAh LiFePo Rx pack battery
Thin CA glue, Welders glue, 3M Extreme packing tape, Gorilla White Glue, Scotch tape
Drywall sanding tool, 120 to 220 grit drywall screen
Straight edge, ruler
Leather hole punch tool, the kind with several hole sizes.
Drill press is nice, hand drill OK
Screw drivers, pliers etc.
|Feb 17, 2014, 05:34 AM|
Part of the fun of flying is having a good looking glider. These fancy tail feathers are a little more work, but they look great. The hinge system has been working great so far, very durable and very functional.
There are some options on how the tail is set up:
1 Fixed, no rudder movement...the plane will fly OK like this.
2 Conventional rudder, easy to build.
3 All flying, harder to build but will allow for some bigger rudder stunts.
4 All flying upper, fixed lower
1 Conventional with horizontal stabilizer/elevator.
2 All flying, highly recommended for this plane; requires 180 servo.
|Feb 17, 2014, 05:35 AM|
Pod and Boom
I have made about 6 pods so far. The first one used plywood on all 4 sides joined by 1/8" bass wood in the corners. Each build gets a little more refined. What I like best is 1/8" balsa sides and 1/32" plywood top and bottom, covered in 3M Extreme reinforcing tape. Easy to build and very durable. I tried to deconstruct one pod, it was really tough to do.
If you fly like I do and crash often, the epp nose cone is a life saver. I had several really hard nose in crashes ( and many other types of crashes) over the first weekend and I brought the plane home without need for repairs. I was also pleased the the pull/pull lines did not slip or loosen up after the abuse the plane received.
The boom is made from a straight carbon tube. I was going to sue a dlg boom but Ken convinced me the straight boom is the way to go. Cheaper and it makes construction easier. I used the P300 from KitesandFunThings.com. I They have a system of tubes with the same I.D. but different wall thicknesses. This allows the use a common size internal reinforcing tube for all of their tubes. On V1 I used a P100, but found it a little too flexible and I had to stiffen it. The P300 seems to be doing the job very well.
The carbon tube is longer than required. Don't cut it to length at first. Drill the hole for the rudder first. If you mess up that step, you can cut off a bit of tube and try again. Once the rudder bearing hole is nice and straight the boom can be cut to length.
|Feb 17, 2014, 05:38 AM|
9" root cord, 6.75" tip cord V1; 5.4" tip cord on V2; I prefer V2
1.3# epp covered in New Stuff 3mil film
AG16 airfoil 60" span, 75% taper, (60% taper on V2) symmetric taper bought from FlyingFoam.com
Ailerons, really full span flaperons 2 3/4" at root, 2 1/4" at tip.
|Feb 17, 2014, 06:23 AM|
Installing tail servos:
|Feb 17, 2014, 05:51 PM|
Flying set up
For the "Mad Stab" I'm using a simple 2PES system derived from work done by Stéphane "pgts". It uses the servo double arm and servo screws that came with the 180 degree servo to form a kind of pulley. This pulley provides huge mechanical expo. The expo is really important when you have +-90 degrees of elevator throw. In the plans there is a template for the elevator horn. The hole positions are marked and will give you the +-90 movement. Some plastic sides keep the strings lined up on the pulley. The none active line goes slack at big control movements but so far this has not created any issues and the strings have never popped off of the pulley. It doesn't seem to create a problem, so I'm not going to fix it.
For the mad rudder, I took another approach. I use the same control horn, but I use a spring return. This set up takes advantage of the slack in the non-pulling side. The spring side will go to 90 with fa less servo movement. What I did is to use an HXT900 servo and a little longer arm. The servo is offset from center using a lot of subtrim. The offset gives more servo movement in the string side direction to get 90 movement there also. It actually works pretty good and is not too sensitive for regular flying. On low rates it feels pretty normal.
|Feb 18, 2014, 09:45 AM|
Thanks guys. Yes come out and fly it... you will flip out! Actually the flips are low skill but they sure look cool.
Ken does excellent, professional level plans. He has helped me with plans many times before, he is an outstanding contributor to RC flying and rcgroups for all the help he has generously provided to me and others, and for the many of his own designs he has also provided; most in the scratch built foamy forum.
For this project, there are just a couple of minor changes needed based on test flying last weekend.
A) The pod is being lengthened a little so that the glider can be built without the need for adding balance weight...I hate adding weight to a glider.
B) The elevator span is being lengthened slightly. It is still slightly undersized. The main symptom was that it hunts a little in pitch. Several things can cause this:
aft cg; I moved the cg further forward and the problem was not fixed
loose pull pull lines; not the case this time
non centering servo, not the case this time
excessive friction in the elevator, not the case, elevator movement was ver good.
undersized stab; eliminating the rest this was my prime suspect.
1 When deploying flaps the glider would pitch down slightly. Normally as flaps are added the glider should pitch up. In this case the pitching moment of the wing was over powering the stab.
2 With a little reflex; which makes the wing pitch neutral; the hunting goes away
Since this happens with a little speed, the best solution is to increase the span of the stab rather than by increasing the cord.
My V1 glider will be getting the pod/boom/tail feathers per plans...and soon after...a little motor.
|Feb 18, 2014, 11:22 AM|
Back home in Kansas my DLG gets the most flight time. Second in line is my EasyGlider electric.
I usually fly the EasyGlider with a relatively small 1000 mAh 3s battery. On a light thermal day it is fun to see how much air time I can get on a single charge. Thermal up, then loop and roll back down to about 200 feet and look for the next thermal. It is not hard to get 45 minutes to an hour on a single battery on a light thermal day.
For those no wind days here in Southern California, I'd like to try a very small motor with a folding prop on the Fusion. I think I can have an adequate power system for about an ounce; 10 gram motor, small esc and folding prop. If I don't like it, I'll just go back to a pure glider.
Who likes to experiment.
|Feb 18, 2014, 02:51 PM|
Chile, Santiago Metropolitan Region, Stgo
Joined Dec 2012
are you going to sell these??
This is exactly what I have been looking for here http://www.rcgroups.com/forums/showthread.php?t=2076077 !
|Feb 18, 2014, 03:26 PM|
If someone wants to offer kits or offer built planes, that is fine by me. The kit makers and plane builders offer a valuable service to the RC community. Not everyone has the skills or the tools to put a plane together from scratch. The kitters/builders often provide their services for little hourly pay and more for the joy of sharing the hobby. I like to see them keep every penny they earn and enable others to share the fun.
Also, if guys want to change/tweak my design, I'm all for it. I especially like to see how things can evolve and improve for the enjoyment of all.
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