Official Freewing Twin 70mm AL37 Airliner Thread

[GliderGuy]

Never could quite understand why the tail end would bend and fall off. Then I see in your video that you don’t use the tape that comes with the plane. I’ve had some fairly hard landings but not to the extent that your video shows. I think the tape helps. I’ve never had any indication that the tail end on mine has ever even thought about bending.

From each side carbon rod up to the top center and over to the other side carbon rod is an unsupported glue joint as you know.

It’s all a matter of how well the assembler makes this glue joint. Did they score the faces of the foam with a razor knife? Did they use sufficient glue? Etc…. The variables can make for a weaker glue joint.

A hard landing, or multiple hard landings, or a moderate crash into an unseen hole (YouTube video) provide sufficient stress to open this glue joint.

My #1 AL37 did it, too. I was flying off a short runway area and could not allow ANY float. I had to “drop her in” so to speak. The glue joint opened up after several landings. Repair included adding internal braces across the seam.

After I wore out #1 and retired her, #2 bird got the carbon rod treatment. I drilled two small diameter holes into the foam running parallel to the side carbon rods but located on either side of top dead center of the fuselage about 2 inches apart from top center. I also read about scoring the foam faces of the joint. When all this went together, now there were 4 carbon rods supporting the joint. 2 small ones about 4 inches long each at the top and the 2 long side rods. Actually, even hardwood dowel rods would work. Anything to strengthen the bare glue-only joint across the top.

This glue joint isn’t about to split now….cosmetic joint tape added or not.

As posted prior, pilot error and the distraction of a non-extended main gear lead me to fly #2 bird into a lamp post. UGH. Total loss. I can happily report #3 bird got the same carbon rod treatment at the top and isn’t showing any signs of splitting even after several hundred flights.

Also, posted earlier, addition of carbon glued onto the top skin of the wing INSIDE the wing wiring channel is a proven way to prevent foam cell boundary cracking on the top wing skin. Bird #1 was retired because of this…got too ugly to look at….see below (my poor attempt to repair the cracks didn’t work).

#3 isn’t doing this. Even after lots of non-scale aerobatic flying. The added carbon inside the wing wiring channel works like a charm.

-GG

[xviper]

Took your advice and added some more internal support with a few wooden spars glued around the seam, and my third flight felt awesome and completely locked-in. I had some issues with the battery moving and shifting the CG a bit on the first 2 flights as well, but have that sorted now too. Appreciate the help! Here are the 2 sketchy first flights, ha:

Never could quite understand why the tail end would bend and fall off. Then I see in your video that you don’t use the tape that comes with the plane. I’ve had some fairly hard landings but not to the extent that your video shows. I think the tape helps. I’ve never had any indication that the tail end on mine has ever even thought about bending.

[ndrew3]

Don’t feel bad - I broke my #1 AL37, too. Same thing / hard landing. Take heart. After bracing was added, I flew her until I wore her out. No more fuselage issues.

Also, suggest you read:

https://www.hobbysquawk.com/forum/rc...176#post301176

https://www.hobbysquawk.com/forum/rc...435#post301435


-GG

Took your advice and added some more internal support with a few wooden spars glued around the seam, and my third flight felt awesome and completely locked-in. I had some issues with the battery moving and shifting the CG a bit on the first 2 flights as well, but have that sorted now too. Appreciate the help! Here are the 2 sketchy first flights, ha:

[GliderGuy]

Don’t feel bad - I broke my #1 AL37, too. Same thing / hard landing. Take heart. After bracing was added, I flew her until I wore her out. No more fuselage issues.

Also, suggest you read:

https://www.hobbysquawk.com/forum/rc...176#post301176

https://www.hobbysquawk.com/forum/rc...435#post301435


-GG

[ndrew3]

Yes….known issue and discussed in this thread. A proven solution is (before assembly) to insert some short carbon rods into the fuselage top near the top center…one piece on each side of top center. The side rods are not sufficient unless you did an excellent job of gluing this fuselage joint. Typically, a perfect glue job is not made.

Post assembly, however, your option is to glue in several pieces of bracing inside and in several places along the seam from the top around to the sides. I even did this with hot glue, but CAUTION you can get a bad burn.

Packing tape may not be the best answer…needs to be a more permanent fix. This joint sees a lot of stress.

Check the bottom of the fuselage, you may find compression fractures. I had to add some external bracing there, too. But…the bottom is out of sight.

If you are good at cosmetic skills, you can trench each side of top dead center of the outside of the fuselage and insert/glue in some carbon or plywood into the trench. Fill/sand/paint - Could even use the white tape provided in the kit to cover your work.

Bottom line….make it STRONG by any method you choose. Tape is NEVER a permanent fix for anything.

-GG

Perfect matching paint / Home Depot

Yeah, I have a couple of decent pieces of wood I was thinking of using as spars for the top and bottom, think that should help a decent amount. Glad to know it wasn't just bad assembly on my part, but wish I would've known before I assembled it! Thanks, man

[GliderGuy]

Has anyone had issues with the back half of the fuselage kinda falling off/drooping down? I took a pretty big slam on my maiden flight landing after the battery shifted forward, glued it back up and it happened again on my next flight with a much better landing. The 2 carbon spars through the fuselage are fine and not cracked or anything, but still doesn't seem super solid.

I just went through and lined the inside where it meets with packing tape which should help, but is this common for you guys? Anything else you've done to strengthen that area where it connects?

Yes….known issue and discussed in this thread. A proven solution is (before assembly) to insert some short carbon rods into the fuselage top near the top center…one piece on each side of top center. The side rods are not sufficient unless you did an excellent job of gluing this fuselage joint. Typically, a perfect glue job is not made.

Post assembly, however, your option is to glue in several pieces of bracing inside and in several places along the seam from the top around to the sides. I even did this with hot glue, but CAUTION you can get a bad burn.

Packing tape may not be the best answer…needs to be a more permanent fix. This joint sees a lot of stress.

Check the bottom of the fuselage, you may find compression fractures. I had to add some external bracing there, too. But…the bottom is out of sight.

If you are good at cosmetic skills, you can trench each side of top dead center of the outside of the fuselage and insert/glue in some carbon or plywood into the trench. Fill/sand/paint - Could even use the white tape provided in the kit to cover your work.

Bottom line….make it STRONG by any method you choose. Tape is NEVER a permanent fix for anything.

-GG

Perfect matching paint / Home Depot

[ndrew3]

Has anyone had issues with the back half of the fuselage kinda falling off/drooping down? I took a pretty big slam on my maiden flight landing after the battery shifted forward, glued it back up and it happened again on my next flight with a much better landing. The 2 carbon spars through the fuselage are fine and not cracked or anything, but still doesn't seem super solid.

I just went through and lined the inside where it meets with packing tape which should help, but is this common for you guys? Anything else you've done to strengthen that area where it connects?

[vduniec]

Nice shot, but I can’t tell if you painted it silver...or is still white? If it’s painted silver, what paint did you use?

Thank you.

I sprayed it with spray paint. The color is called Aluminum. The wings, engine pods, cargo doors and empennage are painted Boeing Aircraft Company Gray. I gave Home Depot the Federal Standard number for it and they color matched it in paint sample. FS 16515.

If I were to paint it again, I’d select the Chrome Silver color. The Aluminum is too grayish and dull to my eye.

[ndrew3]

Finally finished mine up! Pretty happy with it, definitely a couple mistakes though.

Made a little build video as well just for the hell of it: https://www.youtube.com/watch?v=i6Uo4oOMESE

[Sky Wolf]

In flight shot of my AA 738 in the silver bird livery.

Nice shot, but I can’t tell if you painted it silver...or is still white? If it’s painted silver, what paint did you use?

[TomHintz]

I actually got some time to paint and do some lettering. Looking forward to getting this thing in the air!

[vduniec]

In flight shot of my AA 738 in the silver bird livery.

[Topshot19]

Got the maiden done finally! Ordered a gyro for it so it will fly nice and locked in! Fun seeing the blue belly with the delta logo.

[Sky Wolf]

My buddy “Crazy Juan” had an exciting first flight of his new AL-37. Got the basic Motion RC version, with no mods. But exciting maiden, nonetheless!

[GliderGuy]

You can always type these….more properly:

Solid State Gyro or….

Microelectromechanical gyro

While solid state accelerometers are used inside these tiny marvels vs spinning wheels, the function is as that of a gyro.

AND….gyro is easy to type!

Hint: Not that you would not, but keep the mods symmetrical to both sides. I once flew with only one winglet on (waiting for glue to dry). BIG MISTAKE. The roll this induced was BAD!

Side story: Many years ago, I was given a tour of the USS Francis Scott Key (SSBN-657) nuclear submarine during which the engineer discussed the INS (inertial nav sys). A tiny Beryllium sphere suspended in a vacuum held in place with a magnetic field spinning at many thousands of RPM and its orientation was measured by lasers to give the computers the needed INS info. I was impressed! Current INS technology is improved on this…no doubt.

-GG

[xviper]

True, but fewer letters to type. Not sure these little electronic devices should ever be called gyros. I’ve traditionally thought of a gyro as something that spins very rapidly. There’s nothing spinning inside these things. My first helicopter tail gyro sounded like it had something spinning up.

[mshagg]

Interesting thought. I'll give it a try - only connect the rudder to the gyro and see how high I can crank up the gain.

You could stop referring to it as a gyro and call it a yaw damper then :)

[xviper]

It would be interesting to configure the gyro to have gain only on the yaw axis and move from 0 to 100 during a flight to see how it altered the flight characteristics of the AL37.

Interesting thought. I'll give it a try - only connect the rudder to the gyro and see how high I can crank up the gain.

[mshagg]

I think most airliners suffer from dutch roll due to the immense lateral stability from the extremely long wings and the swept angle, the vertical stabs are already enormous so I guess there's a limit to how large they can get.

It would be interesting to configure the gyro to have gain only on the yaw axis and move from 0 to 100 during a flight to see how it altered the flight characteristics of the AL37.

[xviper]

I got re-acquainted with a fellow RC pilot and I had forgotten that he is a long haul 777 pilot (real one) for WestJet. Since the pandemic, those long haul flights have been curtailed and he got a bit of a demotion to fly the 737 Max8 when they started to get re-certified. I told him I had the model of the plane he normally flies in the WestJet livery. He got very excited and wanted to see it fly someday soon.
Anyway, we got talking about the mods I did to my model, one of which was chopping off the lower winglets because I wanted to help control the yaw waggle a bit. I said that to completely eliminate the waggle, I'm putting a gyro back in. He tended to agree with both mods - removal of the lower winglet and the addition of a gyro. He said that in his Max8 training, they went through various scenarios, one being turning OFF the Max8's yaw damper. When that's done, any passenger sitting at the rear of the plane would most likely upchuck their cookies from the plane swaying side to side. So it would seem that the real Max8 relies heavily on a yaw damper and those planes that have only the upper winglet don't waggle nearly as much when the damper is turned off.
PS. I also fly RC with a fellow from DOT whose team is re-certifying both the Max8 and the Max8 pilots in our city (WestJet's head office).