#35 Model Airplane Building Clinic >> DJAerotech Chrysalis 2m Electric Sailplane

[Stevephoon]

Originally Posted by FishHawk

Broke one of the shear webs when trying to align the ribs. My trailing edge notches don't line up that well but I guess this is normal, which makes alignment difficult.
What I did for the sheeting is I used tracing paper and traced the sheeting from the plans.This will help me when I cut the sheeting .
FishHawk

FishHawk,

I did just as Don said with the shear web pieces. I also "removed" a couple of pieces when aligning the ribs. I initially taped them back together because I realized they are cut specifically for each rib and I did not want to get them out of order or orientation. But then, you can still use them while taped....

I didn't have any issues with rough cutting the fuselage sheeting then sanding. This was a first time for me as well, but it came out pretty well.

The alignment of the ribs when the plans are not printed exactly first seems like a big issue. It's not. Go with the pieces as cut and double/triple check the last few ribs and you will be fine. I was worried about that and how the last ribs go on, but it all worked out in the end. I have double checked the alignments of the wings and while the dihedral is a little more than what is in the instructions on the outer wings, everything still came out square. The wing tips are in the same place on both sides when middle wing pieces are "squared up."

The only issue I had was sanding the different materials on the wing. The hardwood spars are much stronger than the surrounding balsa. I carefully used a dremel with a sanding wheel to get close, then some careful time with coarse sandpaper to make everything nice and flat. While not perfect, it's all come out pretty good.

Off shopping with the wife for a few hours, then I should be able to get back to covering. I took today off from work!

Steve

[FishHawk]

Don, I broke the shear itself but the carrier strip is in place. what I'm going to do is align the ribs with a non broken shear web and then when it comes time to glue the shears in place I'll position the web in place between the ribs.
Thanks for your help . FishHawk

[Stevephoon]

Well, it took me a while, but the wing is covered!

Each outer wing was covered with a total of 6 pieces of covering. Two large pieces of the transparent violet, two pieces of black and two pieces of white. I am very slow at covering... This is about 5-6 hours of work.

I have run into one issue. I've tightened the covering on top of the spoilers too much and now they will not easily lay down flat. The little 5 gram servos can no longer pull them shut. Is there a way to relax covering? Or do I have to just cut them apart and re-hinge?

Steve

[Don Stackhouse]

I've seen that problem before. When you shrink the covering, if you run the iron over the film that forms the spoiler hinge, it shrinks, pulling the leading edge of the spoiler up against the aft edge of the spar. The interference keeps the spoiler from closing.

The nice thing about covering that shrinks when heated is that you can stretch it back out again with heat.

Make a shim out of 1/64 ply, or a piece of shirt cardboard. Open the spoiler, tuck the shim into the hinge gap, then slowly, gently but firmly push the spoiler closed again while heating the hinge with your covering iron. Hold it closed while it cools down.

Note, the little "steps" on the ribs that act as stops for the spoiler are designed deliberately a little high, so you can trim them down as necessary to get the trailing edge of the spoiler to sit exactly flush with the wing surface.

[pd1]

Nice job on the covering. Looking good.

[Al_M]

The best way to cover is slowly.

[Al_M]

My Chrysalis can make a loud buzzing sound during climb if it is steep enough. I use the MP JET motor and an Aeronaut 13-8 folder. It started out with 8 CP1300SCR cells but now uses 3 A123 2300's. The spinner doesn't hit anything and there are no signs of anything touching the motor. The esc is a Castle set to outrunner mode. The controls are the good Sullivan snakes with the carbon that they no longer make and the sheath is stuck to the fuselage sides for their length with silicone. I have gotten used to it after 4 years but it still bothers me. I have not duplicated it on the ground and it doesn't start until the plane is far enough up that I can't see if anything is vibrating. I have wondered if it could be the prop. It will stop if I reduce the climb angle to a lot less than what it was when it started. Any ideas? I hope it doesn't lead to the maneuver called " plummeting earthward ".

[Stevephoon]

Originally Posted by Don Stackhouse

...
The nice thing about covering that shrinks when heated is that you can stretch it back out again with heat.
....

Don, Thanks for this tip as well. Worked like a champ! The spoilers are moving free. I still have some minor adjustments to do on the pushrods, but I can tell it will work fine.

Originally Posted by pd1

Nice job on the covering. Looking good.

Paul, Your covering is still far superior to mine, but thanks. I like how it's turning out. It's very different than all of my other planes.

Originally Posted by Al_M

The best way to cover is slowly.

That's the only way I can cover!

Originally Posted by Al_M

My Chrysalis can make a loud buzzing sound during climb ....

My Daddy-O can make some odd buzzing when at high RPMs/throttle and the plane speed is very low. (Pulling out of a hover type thing.) I've wondered about that. It seems to have started when I switched props a while back. Maybe it's some sort of prop noise when part of the air flow breaks from the propeller???

Steve

[Stevephoon]

This area has been slow work for me. I have not quite decided how I'm going to connect to the rear control horns and get the needed throws without hacking the rear of the fuselage and/or having something bump into each other. If I would have followed the plans and had the pushrods just exit out of the side of the fuselage, this would have been easy. But, I'm modding this as well slightly to have the push rods exit out of the back. I've seen others do this and there is even a discussion on this exact topic happening right now over on RC Groups.

I have three thoughts currently,

1. Use solid .032 push rods and just Z-Bends at the tail. This is the simplest, but the pushrods I have will not reach all of the way to the front compartment. This is where I think the servos will end up.

2. Use the included flexible push rod with a Dubro Micro Clevis. http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXJGT2 I have one sitting around, so why not. This is shorter than the metal locking clevis and threaded coupler that is included in the kit. Even with the micro one I'll need to chop the back end some to get the needed movement.

3. Use some micro Easy Connectors. http://www3.towerhobbies.com/cgi-bin...?&I=LXAHE6&P=6 This may not fit either. I have not test fit this yet, but maybe a simple solution.

The decision will wait until I have a few more things mounted and covered and I know where the servos will really be...

Here's what I have done...
First, the control horns were glued to the elevators (is that the correct term on a V-tail?) . I used thick CA and then a filet of titebond after the CA dried.

Each side of the tail was covered with just two pieces of covering. A top and a bottom. The elevator is attached using covering hinges. I first taped the elevator to the stabilizer on the top only with blue tape. This holds the elevator in place and also builds in the needed gap when it's folded back over the stab. The bottom covering goes on first. I started with the stabilizer, then carefully ironed around the hinge joint. Then the rest of the stab. Trimmed and triple checked the hinge area... Then the top covering goes on. I removed the tape and let the elevator sag down. Attached the covering to the top to the stabilizer. I then used a thin piece of cardboard to force the bottom covering up through the hinge area. Then kept covering. I needed three hands, so I didn't get any pictures... Sorry. But this turned out well. I just wanted to make sure the top and bottom covering actually met at the hinge point. Trimed then got most of the wrinkles out. Then did the other side.

All of this took another 4 hours or so over a couple of days. It looks good, and the elevators move nice and free. Perfect!

Steve

[Stevephoon]

I finished off the fuselage today. Each side took two pieces of covering. There are seams near the rear of the wing. You can't see them unless you're right up next to them. Black on the bottom and white on the sides and top.

I took some beauty shots since the sun is out today. It's too bad that I'm not further along. Today would have been a nice day for a maiden. I don't get many of these types of days in the winter here in Michigan. Initialy I thought I would put some gold trim on. (Monocote Gold) but I kind of like the simpleness as it is. I'll probably keep it like this for a while. The covering still needs a few wrinkles worked out and the rear fuselage still needs to be covered after I figure out what I'm going with the linkages.

There is still a lot to do.... All of the guts needs to go in while balancing neutral and being able to hook the spoilers back into the RX... The latch for the front hatch still needs to go on... The linkages need be figured out, hooked up and adjusted.....

Steve

[vicrider]

That looks fantastic steve, good job.

[pd1]

Steve, that came out beautiful.
The feeling you have right now cannot be found with an arf.

Good job.

Paul

[FishHawk]

Started my wings today and broke the tail end of the A rib. The ribs being very thin must be handled gently and I use a little too much pressure when fitting the rib into the trailing edge. I was wondering if I should put a couple of thin braces on the broken section or will the it be ok?
Second issue , the carrying strip on the shear web came loose again but did not break off so I taped it in place while setting the rib alignment.
FishHawk

[Don Stackhouse]

Fishhawk, the A, B, J, K1, K2 and L rib all get balsa sheeting glued onto their top and bottom edges, no reinforcing necessary. Even on the others, if you crack one, straighten it back out and wick in some thin CA, it should be fine.

Hint, when using the shear webs to help locate the ribs when initially framing up the wing, don't try to push the webs all the way down onto the ribs. Just 1/8" or so of engagement is enough.

[FishHawk]

Thank you for the helpful hints. FishHawk

[gramps2161]

Steve been following along on your build you did a wonderful job with this, and she looks great. Here's hoping for some good flying weather to come your way for a maiden flight.

[Stevephoon]

Thanks everyone for checking in. I think it's turning out nice.

I did some quick balance checks and no matter what I'm still a little tail heavy with everything but the battery up front. The good news is that by just sliding a 2200 mAh battery all the way foreward in the wing compartment I can get it to balance at the beginning of the nose forward range of suggested CG location. With a small/light 1300 mAh battery all the way forward under the wing I balance in the center of the suggested CG range. So, my plan is still to mount the battery under the wing and push all of the electronics up front.

I did hook up the tail feathers. I made a last minute change so that the pushrods cross while exiting the rear of the fuselage. This seemed to allow the most clearance. I'll take some pictures tomorrow and show what I did, just in case someone think's it's a bad idea.

Steve

[FishHawk]

Steve, I hope my build comes out as good as yours. FishHawk

[k8zfj]

i've always like the transparent violet , looks great
will u get her in air before 2013?

randy

[Dimeflyer]

The sailplane is a little harder than the sport or comp, type to fudge things but they will forgive some fudgeing if you keep things tight enough to stay strong guy ,
it looks great as far as youve gotten with it !
There is nothing to compare to DIY ,scratch or kit building to make you feel like you know how to do things right !!
George

[Stevephoon]

Some more progress! The guts are in and hooked up! As shown in the picture the plane balances right on the front edge of the suggested CG range. I built up some sticks for holding the tail servos. I needed this instead of the suggested method because I wanted the ESC wire to run along the side of the fuselage beyond the servos.

I also took a picture of the rear end to show how I connected the tail up. It seems to work fine, but the proof will be in the air!

I have a DX7 for the TX. I used a Delta wing setup with the tail servos connected to the Aileron and Elevator outputs on the RX. This way the right stick controls the tail, left/right and up/down. The AR500 RX I'm using does not have an actual flap output, but it does have a gear output. On my DX7 I mixed the flaps to the gear out and did a mix from gear to gear so that the actual gear switch does not actuate the flaps. Then the spoilers were plugged into the gear out on the RX. Everything seems to work fine!

I power tested the motor with the 10x6 folding prop I have. 290 + watts and about 25.5 amps. Should be more than enough power.

What's left, some more adjustments of the spoilers, double checking the washout, centering the wing and marking it on the fuselage and wing...

and, Oh yea, flying!

Steve

[Don Stackhouse]

C/G at the forward limit is a safe move for first flights, but you will see more tendency to drop the nose entering turns, and zoom coming out of turns. We've found that the handling seems to be the best overall with the C/G about 1/16" ahead of the aft limit. Experiment, and go with whatever results in the handling that is most comfortable for your flying style.

Particularly because of the long tail moment arm, the dynamic stability (the ability to damp out oscillations) is especially high, which also means you can get away with less static stability. I've set the C/G about 3/8" aft of the aft limit, so that the plane had slightly negative static pitch stability (pull the nose up and let go, and the plane wants to pull the nose even higher all by itself, etc.), and handed the Tx to a first time beginner. As long as she could see it, she had no trouble staying mentally ahead of the plane. Don't try that with a plane with a shorter tail moment arm.

[Stevephoon]

Don thanks for the Heads Up on the CG. The plan is for a Maiden tomorrow if all goes well. I double checked everything and everything looks like a go.

Also the weight of mine without a battery is 28.1 oz. Even a little lighter than I was hoping for.

Right now the forecast for tomorrow afternoon is Sunny with winds 1-4 MPH, but 40 deg. Sounds like a good day to try. The way the weather is around here in the winter, this could be the last good flying day for a couple on months or more. (Or I could be flying all winter...)

One last question. How much throw on the control surfaces does everyone like? The plans call for 3/8 in each direction. Is that about right? Right now my low rates is set to that and high is about 5/8 inches of movement. Any expo added ?

Steve

[vicrider]

Good luck on your madien Steve. I have my throws set up like yours, more or less. I fly it mostly in low rate. I do not use any expo. I use a Futaba 8u and have my spoilers on channels 5 and6 mixed together, they operate on the retract switch. One thing you might want to consider is mixing in a little up elevator with your spoilers. I have 25 percent mixed in to mine because with out it the plane will pitch down when deploying the spoilers. I'm sure where the plane is balanced will have an effect on how much it pitches down too.

[Stevephoon]

Well, I took her up today.

The first flight went really well! A few clicks of down and a few clicks of right and she would fly hands off. All I did was some lazy circles just seeing how it flys. The motor was crazy strong for this plane. Probably too much. Here are some pics.

Steve