Nodd

I was given this big beautiful 4m Discus sailplane several months ago. To say I was excited, would be to put it mildly.



Upon closer inspection though I noticed the fuselage was pretty beat up. Apparently the winch wasn't up to hauling this behemoth into the air & she came down hard, trashing the front of the fuselage.



Repairs were made, looks like big globs of epoxy & glass on the inside of the cracked areas fixed her up. Structurally she seems okay, she'd probably fly fine as is. These giant scale sailplanes are so majestic & beautiful in the air, it'd be a crime IMO to fly her looking like this though.



I'm not expecting to get her back to a mirror smooth finish, nor do I want to spend a ton of time/money. So I started by sanding back the really bad areas.



While working on the nose area I came across a bunch of Bondo hiding under the paint. Apparently this is not be the first time this poor plane has been to the body-shop.



The lip around the cockpit was in bad shape. I reinforced the weak areas with some scrap wood & used mini-clamps to hold them in place while the glue set up.

Next I did some glass work, mainly on the inside. I added some bondo to the outside to fill in the cracks & smooth out the rough spots. A few coats of primer & then a coat or two of satin RustOleum & she's looking fairly good...



Started installing the radio gear...



The wings are in fair shape, needs new covering here & there...



I'm hoping to fly her in a couple of days. I have a buddy with an EP Senior Telemaster that's offered to tow her. Will post more shortly.

soarrich

My Feedback: (98)

I've got one of those, it's a AK MODELS 4M Semi Scale Glider. I got mine off e-Bay, but I think Nitro Models sells them now. The fuse was very weak, and the ply made hard points against the side of the fuse. I took all the ply out of the plane and CF'ed insides. I flew it a few times, it flies OK. I never really sorted mine out, I still have it a little nose heavy. I was thinking about getting it out of the attic and converting it to electric, it took so much lead to get it to balance that a electric version would not weigh more. My blade spoilers didn't work well, they jammed and got stuck, so I made my ailerons into spoilerons which worked OK.

Nodd

Yes I'm not expecting great things from this plane but it was free & I figure it'll be a good introduction to giant scale sailplanes. I've heard that the spoilers are a pain, the previous owner said he never got them to work properly. I'm planning to hook those up tonight, if I can't get them working I'll do as you suggested & mix in some spoilerons. Yeap Nitroplanes has a slightly newer version for around $160 which is an insane price for a 4m ship. Hopefully I'll get a season out of her before she falls apart again.

soarrich

My Feedback: (98)

If you make spoilerons, mix in just a tad of down elevator, mine pitched up just a little when I raised them.

thailazer

Great progress, and they do indeed look great in the air. Regarding the nitroplanes version, I wonder if the fuse is glass or that cheap plastic?

Nodd

Thanks for the tip on the spoilerons. I have another sailplane that uses them & I've found pitching up a little can actually work for you. Many folks think spoilerons don't do much to slow things down but they are effective if you let the nose raise up a little (the raised ailerons help keep the wing from stalling). The higher AOAcauses drag that in turn slows things down nicely. You just have to be careful you don't over do it & stall. It looks like my blade spoilers are going to be okay though.

The Nitroplanes add says "...The kit features a gel coated fiberglass fuselage...".

Getting back to the spoilers issues I've heard about... I think the key to getting these spoilers to work is to have the control arm facing the way I have it in the pic below. If its installed with the arm facing towards the camera the spoilers will bind for sure...



They seem to be working fairly well although the servos buzz if I try to close the spoilers tightly. Mine are sitting proud a little, something I'll have to play with.

Getting the Lead Out
I visited my local fishing tackle store & picked up a few of their biggest lead sinkers...



After adding a whopping 27oz (765g) she finally balanced. Total flying weight came out to almost exactly 10lbs (4.5kg)...



She's a big heavy beauty for sure...



Well if I can figure out how to fit this in the car I'll be maidening her tomorrow. I'll post video of the flight (or carnage). Wish me luck.

soarrich

My Feedback: (98)

"After adding a whopping 27oz (765g) she finally balanced. Total flying weight came out to almost exactly 10lbs (4.5kg)..."

See what I mean about an electric version being no heavier? [:@] I have a ton in mine also, I used the 1oz size, but a lot of them.

soarrich

My Feedback: (98)

Here's a couple of pix of mine.

Nodd

Yeah I've found that today's lightweight lipo batteries & brushless motors often end up weighing about the same if not lighter then the usual lump-o-lead in most glider's noses. Very tempting to electrify although hand launching this beast would be an adventure. Might have to hit the gym *grin*.

I love what you did with the carbon fiber, wish I'd seen those photos a few weeks back. If she starts to develop cracks or if I put her in I may very well give that a try.

Nodd

Okay so here's how things went...
She caught a wingtip early during ground roll which setup an ugly back-n-forth oscillation. I immediately aborted by hitting the tow release & naturally nothing happened. Maybe a full second later the towline finally popped off but not before everyone got in a chance to scream "RELEASE"! Thankfully Tommy's Telemaster Senior shrugged off the botched launch & climbed out safely. My Discus never got of the ground so that was unscathed also. Upon closer inspection it was determined that my release servo is too wimpy. Apparently for a ship of this size you need around 100 oz-in of torque, my servo has around 30 oz-in. So back to the workbench, time to beef up that release. Over all I had a good day though, switched to my other aerotow glider & had some nice long flights. A big thanks to everyone there for their help, especially Tommy for piloting his Telly. Will try to fly the Discus again soon.

Nodd

Bigger, Better, Stronger, Faster
Okies so I dropped in a Hitec HS-645MG rated at 107 oz/in. Its just a tad bigger than what I had in there LOL...



Installed and ready to fly...



Now all I need is a tow plane.

Nodd

New problem
After a couple of test pulls my tow-loop started to fray & eventually broke. The machined edge of the metal hook inside my release is apparently somewhat sharp...



I'd love to file it smooth somehow but I don't seen an easy way to get at it. I was thinking of maybe using a braided wire to ease the edges some. I don't want to make it even sharper or create scratches/nicks on it though.

soarrich

My Feedback: (98)

You would have to take it out, then disassemble the release mechanism so you could buff the edges of the blade part that captures the loop to do it right. You could make a metal loop out of MIG wire or a paperclip, then just attach the tow loop to it, but I'd make a bunch of them up, you never seem to get them back after your flight.[]

Nodd

I know what you mean about loosing your tow-loops *grin* I can't complain though as I'm guilty of finding a bunch in my pocket that I didn't make after I get home. The problem with disassembling the release is its riveted together, not to mention already glued into my glider's nose. I could hack it apart & replace the rivet with a nut & bolt but a club mate came up with an easier solution...

How to remove sharp edges on a tow release hook
Cut some fine sand paper into an 1/8" (3mm) strip...



Loosely fold it in half, abrasive side facing inwards & insert into the release...



Close the release & using a back-n-forth action lightly sand the hook. You'll feel things getting smoother after just a few passes (don't over sand)...



Once that spot on the release hook is smoothed manually turn the release servo a tad & work the next spot. Repeat until the entire hook is smoothed.

After sanding I did a quick test with a string tow-loop & this time no fraying! So I believe that issue is now resolved too. Thanks Bernd for the tip.

KiwiKid

Thanks for all the work put into this thread and the "Nose Job" thread.

I have one of these "ugly ducklings" in the build queue and seeing what you have done with your builds is really helpful.

Mine will be used for ridge soaring alot. I have some mates with tow planes, but also want to fly it in some large local parks,
so have one of the dorsal electric motors kits that FlyFly sells to try out.

Shame about the maiden, at least the model got away unscathed. You are obviously experienced at towing, but what we tend
to do is have someone balance the wingtip at the start of the run until the airspeed is sufficient to allow aileron control to take over.
With my powered version, I have some streamlined wing tip wheels which will hopefully allow a ROG takeoff.

Slope Pilot

Thats neat.

Nodd

A slightly confused individual over at the Wattflyer forums thinks because this sailplane is named "Discus" that its a DLG (discus launched glider). Here's my response *grin*...

Where the launch peg goes is easy, its where to find a Na'vi to launch it for me, that's the problem :-P

da Rock

It's certainly a sweet thing to do, to have your wife help hold your airplane.

However, you should give her a larger wardrobe budget. Arrhhhh..... uhhhh...... on second thought.......... hmmmmmm

kenh3497

How could ANYONE confuse that with a DLG.............

I do think a two handed launch would be possible. Kind of like the hammer throw in track & field events.... or NOT

Ken

Nodd

I'm headed to an aerotow event in Delaware to try give her another try. Wish me luck.

thailazer

With a glider that big, you must need a full scale Pawnee to get it up! Best of luck on the flight.

kenh3497

Have a great time this weekend with your Discus. I'm sure if you get off the ground it will be a a blast to fly. BTW, just what is used for a tow plane?

Ken

kenh3497

Never mind... I watched your video.. Pretty cool!!!!

Ken

Nodd

This sailplane I plan to take to aerotow events where they usually have giant scale Pawnees, Pilatus Porters & Cubs. This weekend there was even a turboprop Porter at the aerotow, sounded very cool. Locally I know a few flying buddies that have 1/4 - 1/3 scale EP Cubs capable of towing a four meter sailplane. For our Easy Gliders/Raidins we have a Fun Cub with an over sized motor. That actually managed to tow my heavy 100" sailplane, quite impressed. We also have an assortment of Cubs & Telemasters in various sizes. Basically we're not lacking for tow planes *grin*.

Nodd

Back to Square One
Well the good news is she flies, flies quite nicely actually. The bad news is she suffered a hard landing & now looks pretty much the way she did when I got her, all banged up. So I'm back to square one.

The Good News
Lets start with the good news. Here's a video I took at an aerotow event (the first part features my Discus in action)...

View the Maiden Flight Video

The Bad News
One of the two spoilers failed to deploy during landing. I'd noticed it was glitchy the day before but made the fatal mistake of figuring it'd be okay. So when only one spoiler poped up she started to yaw badly. I retracted the spoiler & came in hot, very hot. Rapidly running out of runway I pushed forward on the stick & planted her down... thud. It did the trick & got her stopped before the tree-line but at a cost...







So what to do now?
My plan is to strip out everything in the nose & fiber glass the heck out of the interior. Basically do what everyone suggested when I first started this thread. Although I'd done some glass work, most of my previous repairs were purely cosmetic. This time I'm thinking structural.

Glassing the inside of the nose shouldn't be a problem. My biggest concern is the crack where the tail-boom ends & the tail begins. I'll have to glass on the outside to fix that, hopefully without making her look even more ugly than she already does.

Anyway given the way she flew, I think she's worth repairing. She's a good ship but has some structural issues. Something tells me this'll not be the last round of repairs.