Unicorn rebuild-ideas for lighter &/or stronger?

[Charger]

Gonna rebuild a second Uinicorn. Trying to cut down weight but will still have Astro 020. Old motor tube's shot, but foam is fine. This has been the plane that really helped me to have fun flying. Not looking for all out speed, want to try and maximize thermaling......and when there's little free lift, just use the motor to get on up. I'm going to leave this one @ 48" to keep wing area. Any ideas would be helpful.

[Tomegun]

I think one of the lightest batteries you could get that will work would be 10 Kans 1050s like this:

[][][][][] Front on the left and back on the right
[][][][][]
This would allow for a combo of voltage/forward weight for CG. Also, what kind of covering do you plan on using? I would choose the lightest covering possible which might be packing tape or Solite. Don't know for sure. You might want to do some research to see if carbon fiber tape would save some weight if you used it in place of the regular tape in some places. Note the some places. I wouldn't use it anyplace along the LE for a wing that weighs this much but along the top and bottom it might save some weight while adding some stiffness. Adding some Carbon fiber tape will also help stiffen up the elevons. Stiffer elevons will allow you to move the servos further forward without the danger of high-speed failure which will also help your CG. The only other thing I can think of would be the material and size of your winglets. I think Thor is the resident Winglet expert having tried many different sizes.

[Charger]

I've got a lot of ultracote, so I'm leaning twards that. I hear clear's light so I thinking I'll do the top in that. I's carbon fiber tape the same as strapping tape?

[whichwazup?]

Something else I plan to do on the current Uni project is eliminate the majority of the fiber tape except on the LE and the point of the nose, and maybe just a couple of crossing applications to stiffen since I fly a whole lot better and it won't be a trainer for my son this time around. I also cut Uni #2 down to 40" after reading that most guys don't notice a lot of difference in float or soaring, but faster rolls and overall speed. I too plan to go the 10 cell KANS route and not the 9 cell FAUP A cells that weigh a ton.

I'm undecided about the double horizontal stack or three vertical rows and 1 on teh top horizontally to dget the weight to the front. That Astro 020 is a bit heavy to counter.

[RandyK1]

I saw (a while back) a light wieght Zagi that someone had made, they had 3 hole's cut in each wing to make it lighter, as I recall the hole's were about the same size around as a soda can. I cant remember the wieght, but it was really light. I dont think they used any strapping tape eather, but he only used it for thermaling, no combat or high risk flying. It was here on the e-zone, i'm thinking mabey Tim Hopper, i'm not sure ...R...

[billdad1]

Charger

Old motor tube's shot,

You can make a new motor tube out of a piece of 1- 3/16 in aquarium lift tube. Its much stronger.

I have built 3 Unicorns with it and helped replace a broken tube with it.

Since the 020 motor is smaller just cut 2 or 3 lengths of the aquarium tube about 1 in long. Split them and remove about 1/4 in. section. Use these as spacers.

Wrap the motor with tape and use Marine goop or something like it to glue the spacers around the motor. Then glue the assembly in with just a little Goop at the very end of the tube. This way you can get it out if you need to.

I hope this helps.

Bill

[Tomegun]

Carbon fiber tape is not the same as strapping tape. It will probably be lighter than strapping tape and add some stiffness.

I like the above configuration because it is virtually sqaure and there is not other way to get the weight of 10 Kans further forward.

[Charger]

whichwazup?
I know I needed all the tape I could put on a plane.....but now I'm thinking less weight, more agility and longer runs. I don't want to lose too much strength though. Seems like the KAN 1050 are the ideal pack for now. Tomegun's config looks good. The 020 doesn't really weigh that much more than a speed 400. I think I may cut out the TE a little (Zagi 400X style) to get the motor a little closer to the CG,

[Charger]

I saw that post too and it inspired me to put holes to lighten a ThL. Here's the bottom of that one.

[Charger]

Top view.

The guy I got the idea from is Tim Harris. He has some great ideas. I plan on putting even more holes in this rebuild. I defeated the benefit of the lightening holes on this THL by dropping in a spar and generously using probond. The probond alone weighed an even ounce and I had to use nose weight. Live and learn (sometimes).

[Charger]

billdad1

Thanks for the idea. Based on your idea the 020 does fit nice in the aquarium tube. Since it's a retrofit I'll have to take the old one out and notch the new one anyway. To save weight I might try to just fit the single aquarium tube. I'm also going to try to move the motor closer forward to the CG. I think I saw in one of your post your application of a velcro strap to hold the batts in. Did you go through the foam or attach it inside? Can you replace it if it gets tired. That looks like a good idea. I know my stock Uni's velcro got tired and I started pitching batts.

[Charger]

Tomegun

I had seen the words "carbon fiber tape" before and thought it was just strapping tape. Because of your post I read Hobby Lobby's description and that stuffs amazing. Sound like you are dropping little carbon spars in any where you need strength with very little weight gain. Thanks.....that's the kind of info I'm looking for.

[billdad1]

Charger

I only use a single tube. The spacers are only 1" long, less than the length of the motor.

You can just make a new one and notch the tube to fit over the spar.

On the battery straps, I made a thin plywood floor and epoxied the strap under the bottom of the floor. I did not go all the way around, just about 1/4" around the bottom edge.

My brother Pile Drived his "Corn" into the ground from about 200 ft. up and the battery did not even budge.


Bill

[RandyK1]

Charger, If your going to use CF tape, this guy has some for sale at a good price http://www.rcgroups.com/forums/showthread.php?s=&threadid=182442 just incase your looking. ...R...

[Tomegun]

Man, now I'm going to have to get some more to use on my next wing!

[Charger]

This isn't an instructional thread. I'm just trying some stuff and am looking for any suggestions that aren't too derogatory.

I got all the supplys that people have suggested and am ready to carry on. Got a few folding props following the advice of RandyK1, feel real good about the 39 mm gaupner cam set up. He said he had heard the 30 mm spinner might have some problems and I agree it doesn't work for a pusher. It's a different hub than the 39 mm and the blades rub on the motor because the shaft of the motor on a 020 and a Mega are too short. His prop blade spreader mod is a great idea. I used the black plastic from on old Zagi winglet. I got a scimitar prop too and will check it out.

So here's a picture of the core with 20 1 1/2 inch holes in it and a cut out to move the motor farther forward. I thinned the wing a little in the midline and enlaged the battery bay for two different configs of 10 cell Kan 1050 packs. You can see how thin the foam is on the top of the batt bay but I like how it keeps the smooth airfoil in tact. The black lines are where the some fiber tape is going.

[RandyK1]

Charger, Its lookin real good so far :) Remember, dont use alot of fiber tape, mabe even a narrower peiceof tape if you can. Insted of using 2" fiber tape, use 1", if using 1" tape try 3/4". Remember your not flying combat with this one (are you:)?). Find the lightest packing tape you can. Clear tape is always lighter than colored (same brand) so you could tape the top clear (to save weight) and for the bottom you could color your wing with Blo-pens, thay look like airbrush paint (kinda, but for little kids) Blo-pens have almost no weight and look cool. Dont use them on top of the wing because they will fade (in bright sunlight) but the bottom will be safe from the sun. Do the bottom and them cover in light weight clear tape. I dont know what you are using for wingletts, but I think that "Thor" came up with a good idea about wingletts. He uses posterboard (taped), he says he likes them alot. The poster board could save your some more weight. Looks like your having fun, so I should let you get back to work now (I gotta go fly:) ...R...

[RandyK1]

This Seeker was done with Blo-pens and almost no weight http://www.liftworx.com/pages/seeker.html ...R...

[Charger]

RandyK1

Thanks for the good idea with the pens to save weigh. On this one I'm going to use ultracote scraps, but am seriosly considering that for the next one.

I made a pair of "Thor-Letts" and am impressed with how thin and aerodynamic they are and they look strong enough. The poster board cut out weighed 5 grams and after they were coated with ultracote they weighed 6 grams each. They were extreamly easy to make and coat-very little tendency to warp. I compared them to coroplast wingletts of the same size, which were 4 grams uncoated. I had coated a different pair and it was a pain.

Starting to bury control cables. Found the big holes helpful. Really liked the way the sheaths fit in the open CF tube channel as described by Billdad1, but opted for topside mount as had more constriction with the type of golden rods I chose when using the tube channels on the bottom.

[rwmartin]

Cool project! Keep us up-to-date when you can...

I have also modified a wing (not a unicorn) by cutting 4" by 1.5" 'channels' about two inches behind the leading edge. The cutouts had two inches of solid foam between them all the way down the length of the wing. It worked very well. I found that the framework that the channels created was strong enough to survive even my nasty crashes.

I am considering building another ultralight wing using this framework approach but removing a lot more material to create a true 'lattice' type structure. I want to make the entire model 'flexible under stress'. If I can eliminate the hard points and create enough movement to distribute and absorb crash energies... It would be nearly indestructible... similar to the new ultra-flexible (foldable) EPP 3-D trainers.

[Charger]

rwmartin, are the channels cut all the way through the wing, or a limited depth? The channel concept sounds promising. EPP can probably stand a lot of modification. Are the planes you're talking about power or glidder?

I have been very abusive to my fleet latley, the adrenalin is worth the trade off. As a result, I've had major repairs instead of time to work on this project. I have all the parts I need, it's just a matter of time

[rwmartin]

Hi Charger... the cutouts were both through the wing and to various depths (I don't yet own a digital camera... difficult to explain) I left more material closer to the center cord of the wing in the 'trenches' that I cut to act as a shock absorber. This is were the main weight of the wing (battery pack) was located - so I needed to have enough material to dissipate crash energy.

My goal is more about extreme duribility than ultralight weight. But after studying the design of the new 'sheet EPP' 3-D trainers, I believe this is the right track to take... the less mass the better

I believe an unbreakable plane with reasonable flight characteristics(read: speed 400, not brushless) is a realistic goal. The EPP flying wings already come close. I am doing this for fun and I am not out to prove anything to anybody... I also want to be able to hand over the controls to a novice and not care about damage to the plane.

I am hoping to start on a new Unicorn soon incorporating some of these ideas:

A light weight lattice wing stucture with large amounts of the wing material removed. (rigid but flexible under stress)

Limited use of carbon spars and fiber tape - located to prevent the wing from shearing or cleaving but allowing movement.

A semi-flexible motor tube (silicon tubing) that will flex and fold, not crack under stress.

Foldable prop

Buried servo linkages w/ ball bearing servos (it is not practical to protect the servos with shock absorbtion since any servo movement throughs off the linkages)

Light weight li-poly battery w/ a 'floating' harness to absorb shock crash energy. I am using progressive resistance to slow and stop battery movement (battery moves through multiple levels of resistance (different materials) to absorb crash energy and slow and stop it)

Posterboard or 2mm coroplast winglets (pretty much indestructible)

Possibly a new material for the elevons... the light-weight balsa in the kit is pretty delicate, but since I am not going brushless it will probably suffice.

Thats all I have on the drawing board right now... any hints or suggestions from your experience would be appreciated.

-Reed

[rwmartin]

Charger...

The more I think about it... the more I like the circular cutouts that you used. The rectangular channels that I cut have hard edges, which are much more prone to shearing damage at the corners.

The circle is a much more elegant shape. The circle will compress rather than shear under stress. I think I will use circular cutouts to create the 'lattice' stucture on my next prototype. Various sizes and various depths... hmm... back to the drawing board.

-Reed

[Charger]

rwmartin........I think your goals are much like mine. The circles are so easy. I just took a hole saw and was done in about a minute. Few of the ideas I like are my own. This forum is great to get feed back on cutting edge stuff. I'll post again soon addressing some of your other comments.

[Charger]

As I was doing this build, I got to thinking......This is a rebuild. I origonally used one ounce of glue to put in the the 3 spars. Too much weight for glue and maybe I don't need 3 spars. I also loaded up on 77 adhesive before the first covering job and now I'd have to spray it again to recover. I decided to abandon the all out "light" project for this one and wanted a plane for my Astro 020 geared motor. I put it on this set of cores to test for durability with all the holes in the wings. Well a year later and no signs of weakness. I decided for a real light build.........start out with fresh cores. I will be posting stuff on 2 other light builds and would love to hear anyone experience or ideas in building or flying 48" Unicorns under 20 ounces.

[Charger]

Just a couple of notes on this last build before we move on to the real light stuff. When I had this geared 020 on the last Unicorn it was very quiet, pretty powerful, and looped well. Having a 3.7 ounce motor and box hanging far off the TE seemed like it would add a lot of extra weight. So with this build I cut out the back of the plane and was able to cut 1 1/2 inches off the motor tube and it looked good on paper. It didn't seem as powerful, didn't do centric loops, and was so noisey, we called it the flatulator. People sometimes have to add a little weight to the nose on a stock Unicorn build to get it to balance. It's logical to think....move the motor forward. I decided to move it back out to the stock tube length and see if things changed.

[ReikiMaster]

Charger,

you're picking up a lot of turbulence in the air coming to the prop. One of the things that makes the uni quieter is having the motor (and prop) back farther away from the trailing edge. :)

[Charger]

Now you tell me ReikiMaster...........

To get the motor out of the old thick style tube, I heated it up with a heat gun. That really softens the tube and it peals off pretty easily. I then traced a piece of 4mm coroplast as close to the size I cut out of the plane. Then glued it in with hot glue. Then put the motor in the tube with shoe goo and put her back together by the book. It made all the difference in the world. Nice and quiet, more power,.....and it loops again. The distance of the motor from the TE is best the way it was designed!!! This set up is soo quite, I don't see how the noise could offend anyone.

I modified this battery bay quite a bit. It's unnecessary for lite flite, but will accomodate just about any battery. There's wires shoe gooed into the foam that hold rubber bands. When they break, they're easily replaced. The bay is two teared and holds flat packs and bricks. The batts can slide forward and back for CG changes. The rubber bands hold them in that possition. I'm able to run 10 and 12 cell KAN 1050 packs and not have to add any balast.

[Charger]

Just one thing before I get into some stuff I did different on the Supa Lite Corn......I've seen people post as to which adhesive to use to join the halves of the cores together. The instructions say 77, and I believe it. The two photographs show heavy Unicorns that I've crashed and ripped the cores apart. It's never in the 77'd joint, it seems like the 77 bonds to EPP better than the strength of the foam itself. It's a flexible joint.

[Charger]

Supa Lite Unicorn....the 15.8 ounce funplane.

I have had 5 Zagi's and 2 Wing Warriors, but the Unicorn airfoil works the best in my hands for my style. I like to be able to fly slow if I want and not worry about stalling. It is almost impossible for me to tip stall this plane. That's why I like it so much. This is a Thermal Hunter, making the most of light air and an has extreamley low sink rate. I had a 1 hour 2 minute nonstop flight today and only used 1/2 the normal power I usually discharge from a battery.

Gospel Basic premise: The Ideal lite plane has all the weight at the intesection of pitch axis and the roll axis.....it's imposible, but that's what we strive for. I first glue the cores together and mark the CG line on the upper and lower surfaces of the plane with a heavy point sharpie all the way to the tips of the wings. I like to do the midline also. These are sacred boundries. The further away you get from these lines with your weigt distribution, the bigger penalty we will pay later.

[Charger]

I always like to work with the full 48 inch width. I like all the wing area I can get and it's easier to see when it gets far away.

The next thing I do is take the leading edge from the spar hole to the wing tip and seriously blunt it. It needs to look smooth, but almost flat.

I leave the flat bottom alone with the shaping of the nose. If you see the area you can cover with both your hands spread across the nose, that's the area I reshaped. I make it as thin as it can be and still look reasonable with space for the stuff you're going to put in that area. In the photograph compare noses from Red S.L. and an old war horse corn for thickness. These mods do WONDERS for stability. It's like you made three planes and put them together. The middle plane will rise better that the two outside planes. That's why it doesn't stall. I also blunt the tip of the nose so it's not so sharp. I think it holds up to impact better. 95 % of these ideas, I got from Tim Harris.

More later............

[ActionCommander]

I'm looking forward to seeing all these "ultralight Unicorn" tips in one place... One document...? :)

This thread is long overdue...

Thanks,

- Mark
www.unicornwings.net

[thor4944]

I agree Mark........I am looking foreward to it also.....

[Charger]

Thanks for the encouragement ActionCommander and Thor.

So on this build I used the stock spar in the slot it was meant for. On one of my other Unicorn builds I really slathered the 3 the spars in with Probond and weighed it afterwards. It added an ounce just in glue after it dried. This is fine for a standard build, but not for light. The weight was also far away from the center point ( intesection of axis ). This time I tacked the spar in 6 spots with hot glue and put it in the beds for 20 minutes to make sure the wing was straight.

Now......about those holes. First you need to know where the spar is. In this case I wanted to use carbon fiber tape instead of the wing end spars. So you need to know that possition too. Then I like to see the CG line. My goal here was to save weight behind the CG line. There is a piece of carbon fiber tape on the CG line. Then you can see where it makes most sense to place the holes.

[thor4944]

Looks good so far. I did the same thing with the spar. I saved a little over an ounce without that glue...I never even used the glue....I think I put 3m spray on 2 parts of the spar.....and put Packing tape over each spar....I have so much nose weight that I can push my motor back so far it is so quiet even on full power..it is soooo nice....

[Charger]

On EPP, I like to use a cup drill to make the holes with a regular drill. Just drill right through till you see the tip come out the other side. Stop drilling and pull the drill out. Then start drilling from that other side. I think if you drill all the way through, you'd rip the foam more, so with this you may get a cleaner hole. On more brittle foam, this might be too brutal. Tim says you can sharpen the edge of a open ended can for cleaner, more precise cuts.
More Later..............

[Charger]

Looks good so far. I did the same thing with the spar. I saved a little over an ounce without that glue...I never even used the glue....I think I put 3m spray on 2 parts of the spar.....and put Packing tape over each spar....I have so much nose weight that I can push my motor back so far it is so quiet even on full power..it is soooo nice....

That's a good idea. So put the spar in, peal back the foam a little, and spray 77 in? With my technique, I was a little afraid the hot glue would set up before I could press it in the beds. Yours sounds more forgiving and probably lighter. The cool thing about this kind of build is the bonus you choose to use. Moving the motor back is a luxury. I was reading a build thread and Ron put his motor, I think one foot behind the TE and says he almost can't hear the motor. I'm taking my luxury by moving the battery back closer to the magic CG line.

[Charger]

Oh yeah, the 1 1/2" holes weighted 1/2 ounce on this build which may not sound like much. It is 11.4 % of the foam core though. More importantly it's where the weight comes from......behind the CG and further out the wing. The weight is really a lot more of a penalty the further out away from the axis.

[ActionCommander]

... And you don't need as much strength near the wingtips anyways...

[thor4944]

Cant wait to see the total weight......

[Charger]

FLUSH INSERTS

These don't really help to make the plane light but I think it does help with strength. I wanted to put a 1/16" plywood floors to mount the servos on. These servos came with brackets with rubber gromets for a flat mount. Servocity.com has these brackets for most servos. I like to be able to cover the servo bays with clear covering to be able to check for damage, proper motion, and by loosening the screws, the servos pop right out. Cut the size of plywood, mark the shape on the foam, and cut recess with dremel router fitting set at proper depth. I used hot glue to set the plywood in the foam.

[Charger]

On the Unicorn, there is an ample battery bay located on the bottom of the plane. I knew I was going to use a small battery for this application and didn't need that opening. I glued a panel in figuring it would add some bracing. I wound up cutting a piece of 2mm coroplast and making a panel that fit flush with the bottom. Again I used the router to cut the recess. I first used hot glue to put the panel in, but it fell out. I think the coroplast was too cold and too slick. I then used shoe goo and it's been fine. I made a tape hinge so I could make a little hatch to access the ESC. I glued a little spar in in front of the ESC so a tie could keep the ESC secure.

[Charger]

Covering...........I lightly sprayed 77 on both sides of the plane and covered with Ultracote Lite. The instructions aren't clear and I had some problems with the stuff. I used clear ( which was part of the problem ) on two planes. The first, I couldn't find the backing of the film to save my life, so I figured it didn't have one so I put the film and backing on the plane. It didn't feel right so I posted a question about it here on RC Groups. Someone told me to use masking tape on each side to make little tabs and it would come apart. It works like magic. So I set out on my next project feeling like I knew what I was doing. I pulled the film apart and had a little flimsy sheet that wrinkled very easily and a more substantial sheet. I had marked the surface that was on the outside of the roll and it wound up being the thicker film. So I put a section on the plane. I turned the plane over to put some red Ultracote Lite on the bottom and when I pulled the films apart, I found out I had applied the backing to the top of the plane. It was really stuck to the carbon fiber tape, so I left it. That 77 really works under the film.

more to come.........

[Charger]

WINGLETS

This is a very critical factor because the weight of the winglet is the furthest weight away from the midline of the plane and far away from the cg line too. For a light, thermal plane strength isn't as important as weight. If you want to go over 100 mph, you'll need more strength. Here's a list of weights for some comperable winglets in grams:

Zagi.........8.5
posterboard covered in Ultracote......6
2mm coroplast....4 ( not as aerodynamic because of holes )
plyable foam, carbon fiber reinforced ( TH ) 3 ( used on Supalite )
food container ( depron ) 1

Depron's not a bad choice for the weight, they just get beat up a little. Tim's are more resilient.

[Charger]

ELEVONS

I wanted to try something extreamley small. The ones I used are covered in Monocote. They are off a Wing Warrior Zipper ( 36" plane ) . They are 14 1/2" long and 1 1/2" wide at their widest dimention. In the photograph they are compared to a more standard sized pair on another 48" Unicorn. I have no problem with the size for this application. You do need a little motor power to do a decent roll without loosing altitude.
, but it loops very well. I'll probably go just a little bigger next time.

[Charger]

Power Train

In searching for a light motor rparigoris suggested a Razor 400 with very light weight batteries. When I bought the motor from Bishop Power Products, b-p-p.com , Troy said the E-Tech 3s HP 1200 would bring it to life. I was a little scared I'd be under powered, so I went with the bigger ( 3 oz total ) battery. One interesting thing is on a whattmeter this 15.8 oz plane statics at 105 watts, which turns out to be 6.6 watts per ounce of plane. My 35.1 ounce Unicorn with a Mega 16/15/4 running on 12 KAN 1050's statics 225 watts which is 6.4 watts per ounce. Even more watts per ounce for a fraction of the weight. When I go full throttle it climbs vertical fast. The small elevons make it a little challenge to control. A little down elevator on the trim helps. This light plane really doesn't need this much power. I had found a plastic tube that fits the motor, but Mark describes a technique in the Unicorn instructions, where drafting film can be used to create a motor tube of any diameter. I just put the motor tube on with a couple dabs of hot glue. The photograph shows the comparison between the Razor 400 and the Mega, which is a favorite for standard Unicorns.

[Charger]

CG

After the whole plane was built I put it on the balance beam and placed my intended battery on top to see where it balanced. I was supprised to find how far back I could place it. I marked the space in the top of the plane and made a hole for a snug fit. I put a loop of tape on the battery so I could get it back out. I had set the winglets flat with the bottom of the plane and now I can just set it flat and change the battery out from the top. Since the battery is flush with the top surface it gets a little air for cooling. The battery sits half way between the nose and the CG line. Every time I bring her in I see I've trimed up elevator quite a bit. It's nose heavy with a three ounce battery. I've moved the battery back but need to move it back some more.

[Charger]

Like I said I've tried several different brands of planes. The Unicorn is the most versatile in my hands. I've built them to where I don't need any more speed, but where I always got into trouble is with the slow stuff. Other wings stall more easily with slower speeds. I think it has something to do with the sweep of the wing. In this picture there's a Wing Warrior Ridge Runner on the bottom, a Zagi THL in the middle and a Unicorn on top. You can see the difference in sweep. Unicorn's web site is:
http://unicornwings.site.yahoo.net

[Charger]

Tim Harris has written a book on many of the ideas I've gone over here. He has a web site and says he goes over a lot of this stuff @

http://www.handlaunchaerobatics.com/HTML/LaboratoryPages/Laboratory.html

which has extensive text and photos for many different types of structural and even radio modification (batteries at least).

Tim says.........

"And remember, although not used for combat against other (heavier) airplanes, most if not all of the HLAerobatics mods are designed to survive combat conditions (against the ground, trees, building, you own body, etc.). The tighter mass distribution allows for maneuvering w/ less drag which is good for thermalling, as is the low weight. HLAerobatic mods are also good for dynamic soaring in turbulence behind blunt objects on windy days. They are really win/win as far as giving you a model that you can fly in more conditions and at more sites than a standard slope or combat build theme."

[Charger]

We are blessed with a whole spectrum of air currents. There are few things as exhilerating as taking advange of these gifts. I think a good analogy is surfing. If the surf is up, there's nothing like it, but you have to have a surf board to surf. Fast heavier planes are really fun too, especially when there's no surf, but rip it up when you can!!!!!!!!!

Keep it Light :D :D :D

[Pook]

Thats really great Charger - It really must thrmal nicely at that weight - and glide for ever.

Piers

[Charger]

The plane desribed above may be the perfect set up for air currents as strong as "it almost blew my hat off" force. I want to build another one that is extreme in that I want to cut even more weight. I would love a 48" plane that could get good lift off a asphalt parking lot heated by the sun. I'll build this plane so I can reverse the extreme mods in case it's a total failure, and at least wind up with a similar plane as Supa Lite above.........but this one will be The Ludicrously Lite Unicorn. The changes for lighter weight and concentration of mass will be:

More holes
Lighter spar
Smaller servos....HS 55's
Smaller Goldenrods and control horns ( .032 micropushrods )
Thinner elevons, 3/32's instead of 1/8
Vertical stabilizers instead of wing tips ( I've seen the thread )
Use Ultracote lite, instead of it's backing
Smaller motor and battery, Astro Firefly with P gear box ( 7 probable watts compared to the 120 I get with the Razor ) The photograph shows the Firefly and ESC next to the more standard Mega motor and ESC for this plane.

I will only fly this plane in still air or very light breezes. I don't expect any speed, just an ultimate light thermal machine.

Any body care to guess as to which of these mods will be most detrimental and need to be changed first?

[Charger]

Reshaped core and elevons.

[Pook]

I really do like the re-shaped wings and elevons - it looks very good. Are you sure you going to have enough power with the Firefly motor ? A CD motor might be a better choice.

Piers

[Charger]

I really do like the re-shaped wings and elevons - it looks very good. Are you sure you going to have enough power with the Firefly motor ? A CD motor might be a better choice.

Piers

I probably won't have enough power. The thing that intriges me is 17 gr. for the motor, gear box, and ESC. I'm really curious to see what it would be like. I don't know anything about a CD motor. Are they brushless? How much do they weigh with their Speed Controler?

[erashby]

I probably won't have enough power. The thing that intriges me is 17 gr. for the motor, gear box, and ESC. I'm really curious to see what it would be like. I don't know anything about a CD motor. Are they brushless? How much do they weigh with their Speed Controler?

Brushless-yes
weight-depends about 20-30gr and an ESC Phoenix 10 is 6gr wirh wires (no connectors) There are some places that sell kits or even prebuilt CD motors, but most people probably pull out a CD motor from an old CD-ROM and rewind it.

[Pook]

Yeah you can either take apart an old cd-rom drive, buy the bits to make a motor or buy a fully assembled ready to go motor - obviously the price increases with each option.

www.gobrushless.com - is a very good site all the bits and pieces and some nice custom made cans.

Piers

[raptor22]

Like I said I've tried several different brands of planes. The Unicorn is the most versatile in my hands. I've built them to where I don't need any more speed, but where I always got into trouble is with the slow stuff. Other wings stall more easily with slower speeds. I think it has something to do with the sweep of the wing. In this picture there's a Wing Warrior Ridge Runner on the bottom, a Zagi THL in the middle and a Unicorn on top. You can see the difference in sweep. Unicorn's web site is:
http://unicornwings.site.yahoo.net

The increased glide is from the flat airfoil You could actually increase the glide even further in your extremely-light plane by reducing the sweep probably even more then hte overkill lightening

--Alex

[Charger]

The increased glide is from the flat airfoil You could actually increase the glide even further in your extremely-light plane by reducing the sweep probably even more then hte overkill lightening

--Alex

I don't know as a fact, but I have to believe the sweep of the wing leads to stability also. A couple of weeks ago I was flying the 15.8 oz Corn with limited footing on top of a sharp mountain peak. I flew the plane straight over my head and directly into the sun under power ( not very smart at all ). I totally fell down and lost sight of the plane. I thought, while I was down, turn the throttle off. Then I stood up and scanned horizon left to horizon right and didn't see the plane. I then turned around 180 degrees and did the same thing and didn't see it. The plane was still in the air almost over head just hanging there. I think I'll leave the sweep alone. I don't know for sure, but when I let the stick go to neutral on a Unicorn, the plane seems to right itself more than any other brand of flying wing I've ever had.

[raptor22]

It does lend itself to stability quite a bit, you're right about that.

--Alex

[ReikiMaster]

you mentioned pulling the winglets up flat even with the bottom. You'll actually get better float with them sticking down even just half an inch. They act as a "fence" and keep a bit of air trapped underneath the wing. They keep the air from simply spilling out from under the wing.

In a turn you get air compressed under the wing and without the tipsails protruding below the wing that compressed air just spills. WAnna see how much air you compress under the wing? Put the tipsails dodwn about .... just a little less than half of it below the wing. Mine are on with double sided tape. I can fly by fast, pull up HARD, and blow the tipsails off by peeling them from the BOTTOM. You can see the tops go in toward the center of the plane, the tipsail hinges on the tape and folds inward.

Now I'm not suggesting you run your tipsails like that. But having about a half inch below the bottom of the wing has some distinct benefits.

I'm still running my all stock, speed400 powered, 48" Unicorn. My longest flight to date is 33 minutes. I had to come down cause I was getting a crick in my neck. Anyways... I was thermaling with hawks for the whole time. They'd peel off out of the thermal and soar out over the woods to hunt, and then return to the thermal to gain altitude again. I just stayed in the lift and circled with the others that were there. It's still amazing to me to watch my 'corn get smaller and smaller when I have the motor off. An absolutely spiritual evening's flying for me.

I'll put another speed400 on it. I'm still flying on the one it came with ... hehehe. Gotta be a record for a s400 motor. I think I have 2 whole flying seasons on it.

Hey Mark... got any more like that one? :)

[raptor22]

you mentioned pulling the winglets up flat even with the bottom. You'll actually get better float with them sticking down even just half an inch. They act as a "fence" and keep a bit of air trapped underneath the wing. They keep the air from simply spilling out from under the wing.

In a turn you get air compressed under the wing and without the tipsails protruding below the wing that compressed air just spills. WAnna see how much air you compress under the wing? Put the tipsails dodwn about .... just a little less than half of it below the wing. Mine are on with double sided tape. I can fly by fast, pull up HARD, and blow the tipsails off by peeling them from the BOTTOM. You can see the tops go in toward the center of the plane, the tipsail hinges on the tape and folds inward.

Now I'm not suggesting you run your tipsails like that. But having about a half inch below the bottom of the wing has some distinct benefits.

I'm still running my all stock, speed400 powered, 48" Unicorn. My longest flight to date is 33 minutes. I had to come down cause I was getting a crick in my neck. Anyways... I was thermaling with hawks for the whole time. They'd peel off out of the thermal and soar out over the woods to hunt, and then return to the thermal to gain altitude again. I just stayed in the lift and circled with the others that were there. It's still amazing to me to watch my 'corn get smaller and smaller when I have the motor off. An absolutely spiritual evening's flying for me.

I'll put another speed400 on it. I'm still flying on the one it came with ... hehehe. Gotta be a record for a s400 motor. I think I have 2 whole flying seasons on it.

Hey Mark... got any more like that one? :)


Sure you're not tailheavy? Things don't really work the way your explanation is, and it would dive with the elevons liek that unless you are tailheavy.

--Alex

[Charger]

As far as winglets go, I'm sure I'm loosing efficiency by putting them inboard. I think the plane will look better and I want to see what they look like. I'm trying to bring weight close to the midline as possible. I have already made lines on the wings where I can square off the tips and go for more conventional winglets if this is a disaster. I pictrure this plane being so slow because of it's low weight, I'll just need a little stablization. Thinking about the great soaring birds, if big winglets were that much better, they'd probably have them.

[Charger]

Brushless-yes
weight-depends about 20-30gr and an ESC Phoenix 10 is 6gr wirh wires (no connectors) There are some places that sell kits or even prebuilt CD motors, but most people probably pull out a CD motor from an old CD-ROM and rewind it.

I'm sure Piers is right by saying I won't have enough power. I really like the idea of these CD-Rom motors. They look great and are only 1/2 the weight of the motors normally used on Unicorns. I knew nothing about them so thanks for the idea. I have a second Razor 400 in another plane and will probably use it when I wreck that plane and power up this one. It is also 27 grams, so I hate to go to the effort for a CD when this motor has more than enough power. I put the plane together enough to where I could do some power tests. I was going to use the Firefly with a 2s Kokam 340. I hooked it up and powered it up nose down on a scale. It registered 1.2 oz of thrust. I then did a test on my 15.8 oz Corn with a Razor 400 with the E-tec 3s 1200 HP. I came in at over 14 ounces of thrust on the scale. I'm sure this test is not accurate, but is good for relative comparisons. I figured I'd be OK at 1/2 the power but not 1/14. The kicker is I'd need to add 2 oz of nose weight to balance for the Firefly, which totally defeats the purpose.

[Charger]

I have had a couple of other problems with this build. I had completely buried and covered the little Dubro control wires. I knew they had some friction when I put the intended bend in them, so before I sealed them in I carefully applied some graphite powder to the inside of the tubes. After I ran the wires there was still major binding. I didn't think that would work well with the HS 55's, so I cut through the film, dug them out, and replaced them with heavier Golden Rod cables with their heavier clevis' and horns. Another mistake is when I bought the thinner balsa for the elevons, I was excited about how ridgid the "board" was that I got. Each elevon weighed 9 gr before covering. I've weighed full sized elevons for Unicorns, and have some that came in lighter than that. I thought they might be OK, but I fully expect to take them off and cut them down some more to lighten them up because every set up I've tried needs nose weight. I have them covered with Ultracote and fully attached and hooked up to the elevons right now. Which is another problem. I really like blend derm tape and used it to do some over/under strips and full length top and bottom strips too. It's just too loose and sloppy. The elevons keep popping up above or below the surface of the wing. I won't mind replacing it when I cut down the elevons. When I was putting the plane together I could tell it was going to be tail heavy, so I put a heavy 555 receiver in front in the battery bay and buried the antena in the foam, under the Ultracote. Now I wish I could put the battery there now to help balance things since I know I have to go to a heavier battery, but you just don't know untill you get to the finish.

[Charger]

All is not a total loss though. It balances out to be a pure glider with .7 oz nose weight, for an all up weight of 11.1 oz. The lesson I'm getting from this is.....keep as much weight off from behind the CG line. I guess I'll fly it like this untill that motor gets freed up from my Zagi THL. By the way, it looks like Zagi has finally stopped making THL's. It was the last of their old style planes and as I understand, the standard for light weight foam wing gliders. I guess it's because now you can have a nearly indestructable EPP wing instead of styrafoam that's nearly as light.

[raptor22]

I'm really wondering if it will be stable enough with those tins so far forward. You may want to try putting a slightly larger one on a boom. then you will be gaining effeceincy and stability, rather than the other way around.

Hope its not an issue.

--Alex

[Charger]

I'm really wondering if it will be stable enough with those tins so far forward. You may want to try putting a slightly larger one on a boom. then you will be gaining effeceincy and stability, rather than the other way around.

Hope its not an issue.

--Alex

You're probably right. Didn't you fly a Corn for a while with no winglets at all? I have a little too. It's squirelly (sp) , so I figure somethings better than nothing, for an experiment :rolleyes:

[raptor22]

yes, I did. Was perfectly fine cruising around. But it suffered at very slow speeds and aerobatics, and you built it specifically for slow speed so I thought I'd mention it.

I experimented with a central fin sloper (on a boom), and it worked even better than winglets.

Hope it works well.

--Alex

[Pook]

Charger,
It looks really nice hopefully you'll get your balance issues sorted out. The Razor motor is the way to go if you already have one of those & should have plenty of power.
I see youve had fun with the carbon powder :) I managed to drop a whole tub of the bloody stuff once went every where.

Piers

[Charger]

I have had some real success with this set up :) , but I am experiencing a paradox. When I fly the plane, I wind up trimming it to full up elevator. At this trim, when I do the "dive test for cg" ,it dives strong and keeps diving strong with hands off the stick and I have to intervene to pull 'er out ( CG too far aft ? ):confused: :confused: :confused: I move the battery back 1/2" aft and I didn't really feel a change. When I cruise around, it's real stable and holds elevation well. Here's another question: I feel a f wing should be set up to where the elevon angle should be set even with the surface of the bottom of the wing and you should work on CG till you get that pretty well set to minimize drag. Is that reasonable???

I will back track in future posts to fill in the gaps on this project.

Here's a pic of the trimmed up elevon.

[raptor22]

Yeah, it should be even with the bottom. wierd.

I have to say I think the elevons are flattening to cause the dive.

[Magnum9]

For more on using lightening holes in EPP and that lattice idea, check out this thread - http://www.rcgroups.com/forums/showthread.php?t=286526

[erashby]

I have had some real success with this set up :) , but I am experiencing a paradox. When I fly the plane, I wind up trimming it to full up elevator. At this trim, when I do the "dive test for cg" ,it dives strong and keeps diving strong with hands off the stick and I have to intervene to pull 'er out ( CG too far aft ? ):confused: :confused: :confused: ...
Here's a pic of the trimmed up elevon.

Check the motor thrust angle: How is it trimmed to fly at full throttle vs. half throttle vs. with the motor off?

Also check the elevon flex in a dive-have a buddy dive the wing and you look with binoculars at the elevons.

[Pook]

Erashby - I think that ones a glider...

Piers

[Up&Away]

How are the HS55's holding up? I would have thought they wouldn't have enough torque once you get the 'Corn up to speed.

RW

[Charger]

I want to catch up with what's going on with this project. I could not see going to all the trouble of making this plane so light only to add .7 oz of lead just to get it to balance as a glider especially knowing when a motor is placed, I'll still need probably more weight. So I took the elevons off, cut some of the length off them and popped some holes in them. It only saved 3 gr and also the weight of the tape for the extra length. **********Big piont: I was able to eliminate all the .7 oz nose weight to balance. This is like the skinny guy at the end of a teeter totter :o being able to lift a heavy guy sitting near the fulcrum********* That's why I really hate to see magnets or velcro to hold winglets on. It's not so much the weight, but where the weight is at. Took it out to a field for some test flights with the Firefly on and we could see it almost have enough power with the folding prop to get some altitude. Didn't quite work, so i popped the motor off and converted it to a glider and my buddy took it up a hill and flew it for about 5 minutes straight, so I could take some photographs, and it handled really well, except it had to be trimmed almost full up elevator.

[Charger]

Next I took it home and tested 4 different props with the Whattmeter. The folding prop had the lowest watt reading and the prop that the motor came with ( gunther prop), had the highest, almost double the watts ( about 7 ). I went to a field and the plane cruised around at about 10' for about 5 minutes with a 2S 340 ma. Then I put a 2S 1200 ma in and was able to get up to about 100 yards ( WOT ) and tried to make it to a hill, but chickened out and broght her back. Later I went up a hill and with almost no wind really had fun for about 15 minutes and used the power to get back from some dead air and was able to use the power to make a few landing attempts. I brought it in to check the CG because still full up elevator trim, made a change, but it didn't make a difference. But had another real fun 15 minute flight.

Big Point*******I could not see any control issues with the winglets in the fin possition********

[Charger]

Took the plane with the motor on yesterday and It was reall making the most out of light air. The real fun for me with these light set ups is it's so relaxing just gliding along getting free lift and long slow speed flights in very light conditions. Both of these planes have almost no stall. The stall is...focus on the nose....hold it right into the wind......up elevtor.....the nose dips about a foot and recovers on it's own....that was it :)

The all up weight of the Ludicrisly Light Unicorn is******* 9.9 Oz including motor and 2S 340 ma battery at the full 48" :D :D :D

Here's a big problem I did have though... I was seriously almost specked out and climbing just on thermal/ridge lift. Nosed into the wind. I got blown to the side a little and I was going to make a 360 degree turn and nose back in when the plane started to dive. It absolutely would not respond to any controls and was diving straight down. I didn't know this plane would move that fast. It wasn't an electrical problem. The plane nosed straight into the ground from about 1,000 ft. I thought the plane would be in shatters. ********** another big point.. it take mass to cause damage. The spar was broken and the lipo broke a solder joint. I couldn't tell where the plane impacted, no surface marks. That was it :p I built this plane with a very light and strong spar and know they're brittle. I didn't glue it in on purpose. I got home and it literally took me ONE minute to replace the spar. I had marked the plane where the spar goes, poked a hole on either end of the spar hole. When I slipped the new spar in, it pushed the old broken spar out and that was it :D :D . I had played with CG on the field before the flight and really don't think that's the problem. I got home and did some tests and found the servos were very sloppy in the foam. I didn't think there would be much force on them and had relyed on a friction fit with the foam. I don't know if they loosened on impact or were loose before. I'll secure the HS 55's and see if that was the problem :confused:

[Charger]

Also check the elevon flex in a dive-have a buddy dive the wing and you look with binoculars at the elevons.

Yeah, it should be even with the bottom. wierd.

I have to say I think the elevons are flattening to cause the dive.

Right now I think your'e both right. I need to secure the servos better and retest. I hope it's that simple.

The problem was with the plane as a glider, so thanks, but thrust angle isn't a problem.

[Charger]

How are the HS55's holding up? I would have thought they wouldn't have enough torque once you get the 'Corn up to speed.

RW

The Jury is still out. No doubt these servos would be a bad idea for a Unicorn of a pound or more or one that is going to go over 40 mph. This is a very specialty application, Go light and slow. I'm still optimistic. I'm having some problems, but I want to make sure It's not loose servo mounting , before I pass judgement. They were extreamly loose after my impact, may have been loose before too. I have had many fun flight with this plane and the 55's. I'll keep you posted.

[Pook]

It really does look great with the light comming through all those holes....


Piers

[Up&Away]

Don't you think the loss of control could be because of not enough torque produced by the servos? She may be light, but speed is speed. And the 55's are just not upto it. Remember, she's a Unicorn (no matter how light you build her); not a little parkflyer.

[Charger]

Mystery solved. I don't feel real smart violating a simple thing like making sure the servos are in securely, but that's what the problem was. I popped the servos out, wrapped them in masking tape, and hot glued them in. Went for about a 15 minute test flight and no real problems. I did some dives and was able to pull out no problem. I even did a couple of loops. We won't talk about rolls ( OK, altitude falls off too fast). The plane does steer like a boat and the elevons do flutter a little. If I was building for stone cold performance, I'd make the elevon's the same area, but make them about stock length and proportion, just thinner ( from the TE ). I'm sticking with the Firefly and the 55's on this one for now. This plane is much more like flying a high performance kite, than a 12 cell power corn......for sure. It's way fun though in light air :)

[Charger]

I really like the "Dive test" for fine tuning CG's. It has helped me a great deal. I can use it, but for the life of me I can not understand the mechanics of why a nose heavy plane does not continue to dive :confused: :confused: Any explaination would be welcome.

I had used a golden rod tube to run an antena before, but that's really expensive. It did save me a lot of work exchanging Rx's in a recent build. Yesterday I was at my LHS and found Dubros antena tubes and they only cost 99 cents and are a nice small diameter. Tonight I had to cut an antena wire to dig out a broken Rx and will have to resolder it. I think I'll use these Dubro tubes to run antenas from now on.

While I was at the LHS, I bought some chrome monocote and will use it on the top of my next Unicorn build and run the antena tube on the bottom of the plane. Has anyone experienced Rx interference from chrome monocote even when there's been 1/4 inch clearance from the antena wire :confused:

[Magnum9]

I use Robbe quick disconnects on all my planes. You can just leave the antenna leads in and hot swap receivers to any plane without any problems. Actually you only need to buy one set because once you have the female on the receiver you can make your own males from 1mm copper or piano wire and just solder and heatshrink it to the antenna wire.

http://www.aircraft-world.com/shopexd.asp?id=782

[raptor22]

I really like the "Dive test" for fine tuning CG's. It has helped me a great deal. I can use it, but for the life of me I can not understand the mechanics of why a nose heavy plane does not continue to dive :confused: :confused: Any explaination would be welcome.

It is because we need to trim more "up" to get it to fly level. At speed, the "up" trim becomes more effective since you have more air over the surfaces and makes it want to pull out.

[Magnum9]

I also use inverted as a test for CG. Too much rear CG requires too much down trim, which will pull out of inverted flight as an outside loop.

[Tomegun]

Can someone tell me the CG for a 42" unicorn? I haven't had the Unicorn in the air for a while for one reason or another and I'm going out this evening.

[Charger]

I also use inverted as a test for CG. Too much rear CG requires too much down trim, which will pull out of inverted flight as an outside loop.

I can see the dive test, now this.....This is good stuff. Anything to crosscheck the balance and trim of your plane is what I want to know. OK so you're flying inverted and trim it while your flying that way.......so the plane will have a tendency to do an outside loop when the CG is aft. And I assume it'll be the opposite if it's nose heavy. Is it true though, that you need to have a higher angle of attack to maintain inverted flight because the bottom of the Unicorn is flat and the top is curved :confused:

Tomegun......the manual says 9.75 inches from the nose is a good place to balance your 42" Unicorn

[Magnum9]

Not sure about the angle of attack while inverted, but what I meant about checking the CG is to trim it right way up, then fly inverted. Tail heavy will need too much down trim and nose heavy will need too much up trim while level, right way up. Obviously this will reverse when inverted. Some people, myself included, like a CG which is a little more aft than recommended, to make the wing a bit more responsive. Go too far however and they stall into a spiral real fast.

Generally speaking, I have found the inverted test to give a nice predictable handling CG on all kinds of aircraft, not just wings. It is easier to be slightly on the nose heavy side and still be able to control it, albeit with some up elevator, than to have it stalling or porpoising without warning.

[jamesshaw89]

It's been a while since an update and the weather is getting better for flying/thermalling.... so how is it going?

List of lessons learned?

What would you do/not do to make the "ultimate wing"?

Thanks, Jim.

[Charger]

It's been a while since an update and the weather is getting better for flying/thermalling.... so how is it going?

List of lessons learned?

What would you do/not do to make the "ultimate wing"?

Thanks, Jim.

Thanks for your interest. For me flying a good light weight Unicorn is pure stress free fun. I have had flights for over an hour with plenty of power to spare on a single battery.

I'd be glad to tell you about how things have gone with this project ( I couldn't be happier ), but just got back from http://www.rcgroups.com/forums/showthread.php?t=377530&page=27#post4015333 post 404 and need to recharge ( myself ) I would like to be detailed in my responce. Will try tomorrow. Any questions or suggestions for improvement or reports of others success along these lines would be welcome.

[jamesshaw89]

Welcome back Charger... glad you had fun checking out the fast stuff!

Can you describe what a "thermal turn" is to a flying wing? I was trying bank and elevator like a regular glider and it didn't seem to like it much... how do you stay in thermals with this? I'm going to try larger banked circles and see how that does?

Have you tried high starting it up? I never thought about this until I read about Zagi THL stuff. I'm going to try this this weekend if the LHS has a light weight high start.

Thanks, Jim.

[Charger]

It's been a while since an update and the weather is getting better for flying/thermalling.... so how is it going?

List of lessons learned?

What would you do/not do to make the "ultimate wing"?

Thanks, Jim.

I'll share about 3 48" Unicorns build in the "light pursuit" ( Good, Bad, and Ugly ). First my favorite, the 16 0z AUW. Been flying the heck out of this one for nearly 7 months and No major problems. I always want one of these. Some days I don't need the motor ( Razor 400 ). On other days the motor's needed. The 1200 3s Lipo gets a little hot if I race around too much, but it balances the plane perfectly. All the power you need to get out of a tight spot and blast around for a few minutes ( loops and rolls ). Great for field launch and motor over to hills and thermals and light enough to fly for long periods motor off.

The 10 OZ. AUW. This one is a bit of a surprise in it's durability, strenth, and resilience. Right off I wouldn't recommend this build for anyone as their first or second plane in their fleet. Mainly because it is a motor assisted glider. You can not count on a field launch. It is possible in the perfect wind conditions, but don't count on it. It is really a fun plane in light wind and thermals. I can't beleive the origonal inboard fins are still in tact. They are just on little balsa cletes, taped on top of the covering. They are No limitation to control. Some times I can make a turn without covering any ground. Other times, it's a little sluggish, but always comes around. So this one needs a ridge launch. 6 oz lighter than above plane, so really does well in light air, but is sensitive to too much wind or not enough. You'd be surprised how much wind speed these two can handle. I should issue a warning about the HS 55's. They are fine for every thing, but on dives, I feel them give way a little. I would probably say the 55's would be good on a plane 8 oz or less. I don't want to add any weight to this plane, so I just don't do extream power dives. The biggest problem with this plane, is the Gunter prop keeps popping off the Firefly. I tried CA, but the prop bottoms out on the bering and I keep gluing the prop to the motor. I will leave this plane as is and it is fun.

Cont. next post..........

[Charger]

The Ugly :mad: After being very happy with the first two really light builds, I thought I'd build a Unicorn with a regular sized brushless ( Astro 020 ) and keep that real light. Target weight: 25 oz with 8 cell GP 1100 pack. Normal wing tip to wing tip spar, no adhesive. Lighter weight wing tip spars, no adhesive. Minimal straping tape. Nomal every thing else ( 12 holes ). Couln't get the puppy dialed in, so went to 10 cell. Flapped like Duck! Popped some holes in the Ultracote and spot hot glued the spars in and tested with 8 then 10 cell packs with the same exact result as above. :mad: :mad: Took it home and stripped off the covering, added more adhesive to spars, more strapping tape than I wanted and recovered with Ultracote. No more flap, but she's gaining weight captain! Still really hard to get her dialed in. Finally got the CG right with the 8 cell as far aft as it would go, but it really wanted to dive. Brought her in and realized The elevons were flattening out at higher speeds. May be flexible elevons. I got a little too much chopped off the tube that holds the buried control rods and the cable flexes too much. The servos are glued to the foam and may move a little and I used Dubro ez conectors, that are a little sloppy. This should have been an easy build but.......OBJECT LESSON: extra weight puts propotionally higher stresses on the airframe. Sill got work to do on this one and she's up to 27 OZ but will be a fun plane if I don't jump up and down on it too much :o

[Charger]

Welcome back Charger... glad you had fun checking out the fast stuff!

Can you describe what a "thermal turn" is to a flying wing? I was trying bank and elevator like a regular glider and it didn't seem to like it much... how do you stay in thermals with this? I'm going to try larger banked circles and see how that does?

Have you tried high starting it up? I never thought about this until I read about Zagi THL stuff. I'm going to try this this weekend if the LHS has a light weight high start.

Thanks, Jim.

To me a "Thermal Turn" is tightening up a turn because you're getting drawn up too fast. You need an obvious thermal to do this. You want to stay in the thermal and you have the lift, so you don't loose elevation even though your contol surfaces are draging. If you didn't tighten up your turn you either porpoise into the thermal and fly right out of it. I'm probably wrong.

There are books on Thermal flying. I have a video http://radiocarbonart.com/Pages/asecthermalmain.html but the action, as I understand it, is pretty simple to get altitude, either circles or figure eights. I get creative flying blowing off my altitude.

We have tried bungi launches. Even if you had 90 % success, the failures are nasty. For me, nose ins at high speed, still attached to the line. Also, these extreme light weight birds might not have the strength to resist flap and/or snapping under the power of that elastic. We had some success making one of my Unicorns into a tow plane. http://www.rcgroups.com/forums/showthread.php?t=178336 It was a lot of fun, but still too much carnage. For me, with conditions of less than 20 mph winds, I perfer to have a motor. The Razor 400 and a 3s 1200 lipo and esc only adds about 4 oz and so doesn't add much dreaded mass. I can always afford 4 0z for predictable powered performance on a 48 inch wing.

I really hope you have a great deal of success ;) , because this type of flying is so much fun, you'll want to run around, grab people by the shoulders, shake them, and say did you see that!!!!!!!!!!!

[jamesshaw89]

Wow, thanks Charger, that was a lot of info! I bought that video about 4 weeks ago and have watched it at least a dozen times! The best luck I had was cornering a thermal duration guy at the field and he watched the plane and told me what to do and it went up, up, up! it was my lightweight DLG (with a motor) but now I have specked it out 3 times all by myself! that is so much fun. The turning with that plane is insane banked @ 30-45 degree's and circling very tight and quick. The wings I don't think are capable of this? I'll find out more this weekend as I'll going to get some more practice.

I watched some more bungie video's yesterday and they look both cool and scary... my planes are WAY too fragile to take a real bungie launch though. I will try a super light weight high start this weekend and see how that does? if I can get 100' I've got a chance. LOL I watched Dr. Mark Drela HAND launch and then proceed to thermal out his 3 meter "Bubble Dancer"!!!! 20 feet to ??? several hundred it was like watching a magician.

I'm also going to get one of those eagle tree systems thermal gliderunits later this month, at least that is his projected release date... That is one heck of a system they have! but $400 to find thermals? I still think it will be worth it as I get frustrated when I am not "seeing" the lift I know is out there!

Jim.

[Pook]

Jim any chance of a photo of you motor-DLG ?

Piers

[Charger]

I'm also going to get one of those eagle tree systems thermal gliderunits later this month, at least that is his projected release date... That is one heck of a system they have! but $400 to find thermals? I still think it will be worth it as I get frustrated when I am not "seeing" the lift I know is out there!

Jim.

Hay Jim, I have never heard of this. What is it? Any links?

Piers..............You've had some serious thermal runs. What do you have, ridge lift? I can't imagine massive thermals in England, do you get them?