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Linkage pushrods flex on FT Storch

nhk750

Aviation Enthusiast
#1
The title says it all. is there a better pushrod other than the ones in the speedbuild kit? I am seeing allot of flex on the elevator pushrod and some flex on the rest. I saw the post about making stiffer pushrods, but I'm just looking for something a little stiffer without all that work...
 
#2
You can get heavier gauge push rods from many hobby stores, they do add weight. The best way is to put the push rod in a sheath that you can glue or bolt down to the air frame everywhere except a few inches at the ends. Flite test has done this some by putting a zip tie around the push rod and gluing the zip tie to a hole in the foam. One of my balsa planes has extremely light pushrods. I think they might be 1/32 steel or something. All that was needed to make them work was 3-4 small 1 cm long plastic tubes glued to the air frame at intervals to keep the wire rigid. Same concept as how the brake cables on a bicycle work.
 
#3
The method I use is bbq skewers, heat shrink, super glue and wire or bobbie pins for the z bends.

If you have had any ultra micros you know the drill....

Put the z bends in the control horns with a good 2 inches on each. then take a bbq skewer and slide two 1" or so heat shrink tubes (of similar diameter) to the middle of the skewer.

Place the skewer on the push rod wire and slide the tubings over the wires and the skewer. You may have to cut the skewer to allow space for rotation.

Dab some super glue on the skewer and wire under the tubing and let it run, apply heat to shrink tubing and repeat to other end whilst centering control surface.

Attach two skewers for longer distances or just move the servo closer to the surface and buy servo extensions, and a heaver motor.

It is stiff and light and super diy but perhaps a bit of a chore.
 

nhk750

Aviation Enthusiast
#4
Both great ideas, first I need to fix my Storch....Had a bad crash yesterday involving trees and high tension power lines...anyway, the empennage is almost severed from the fuselage. I'm devastated...I think I can fix with some hot glue and extra foam board (the W&B will be crazy though), possibly make a new fuselage...the wing survived however...I'm ok...physically...
 
#5
Both great ideas, first I need to fix my Storch....Had a bad crash yesterday involving trees and high tension power lines...anyway, the empennage is almost severed from the fuselage. I'm devastated...I think I can fix with some hot glue and extra foam board (the W&B will be crazy though), possibly make a new fuselage...the wing survived however...I'm ok...physically...
Sorry to hear you crashed. I did that once with a balsa park flyer... not very pretty. One tip on your repair, hot glue is really heavy so go light on it. It is much better to replace sections with new material. My suggestion would be to use hot glue to tack the broken pieces in place. You can also use tape, skewer sticks, and pins to hold pieces in place. Once the piece is tacked on, make a splice joint to strengthen it.

First, pick the largest flat surface that makes up the joint. Cut off the exterior paper and core foam to make a slot on either side of the break. Use spray adhesive to glue some lightweight printer paper on the inside paper wall that remains. This will act as a doubler to reinforce the skin. If you have access to both sides of the foam, put this doubler on the back side of the paper before cutting a slot.

Next cut a piece of foam board that is about a half inch larger then the slot you cut. Remove one side of the paper and cut the foam back to the size and shape of the slot. You should now have a slot cut in the surface with only the back side paper and doubler patch remaining. You should also have a piece of foam just big enough to go in the slot with a border of about a half inch of extra paper around the edges. Use spray adhesive or gorilla glue to glue this foam patch in the slot.

Repeat these steps for all major flat surfaces requiring repair. Once at least 3 sides are patched and cured, remove the tape, hot glue, and other stiffeners and repeat the process for the parts of the joint that were hot glued or inaccessible with the tape on.

If the glue was applied correctly, this process should leave you with an air frame that is actually stronger then before the crash and only marginally heavier. Sorry for the long description. I would have made a video, but I don't have any foam board right now to demonstrate with and my hobby budget is tied up with other projects.

You can always just hot glue it back in place and deal with the weight if you need to be back up in the air immediately. I prefer to add as little weight as possible.
 

nhk750

Aviation Enthusiast
#6
Nice!, You got my brain working now... I like the repair method, I'll throw a few pics up when I get a chance. Probably going to pic up some foam board at DT and give scratch building replacement parts a try too.
 
#8
I've built two Storches now. The length of the control rods are fairly short. Especially if compared to the Explorer or the Sportster. I wonder if its your hinges having a tad to much glue causing them to be stiff. Just a thought
 

nhk750

Aviation Enthusiast
#9
Ya, its the first foam board I have made and the rudder hinge was a little stiff for sure. I may do the tape weave hinge on the next build. I am going to scratch build a new fuselage this week since we have big storms here in the Pacific Northwest for the next week and cant fly anyway.
 
#10
Ya, its the first foam board I have made and the rudder hinge was a little stiff for sure. I may do the tape weave hinge on the next build. I am going to scratch build a new fuselage this week since we have big storms here in the Pacific Northwest for the next week and cant fly anyway.
Stormy on the we(s)t side also? Over here on the eastern side of the state we had a big wind blow through last night that wiggled one of my towers and knocked out the power to another this morning. You know it is blowing when a customer says the power lines were a little sparky.

If you do repair that fuselage, you can probably thin out those glue hinges by running a cloth covered iron over the glue surface or better yet scraping it with a hot knife on low. Just make sure not to stay in one place long enough for the heat to soak through in to the foam.
 

nhk750

Aviation Enthusiast
#11
I messed up the whole bevel cut thing and had to tape and use to much glue on the hinges. I just cant seem to perform the magical bevel cut. Josh makes it look so easy, maybe I will try sanding next time...

I also noticed that hot glue doesn't stick very well to the water proof foam board. I'm using the regular white board next time and Minwaxing when done.
 
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#12
The method I use is bbq skewers, heat shrink, super glue and wire or bobbie pins for the z bends.

If you have had any ultra micros you know the drill....

Put the z bends in the control horns with a good 2 inches on each. then take a bbq skewer and slide two 1" or so heat shrink tubes (of similar diameter) to the middle of the skewer.

Place the skewer on the push rod wire and slide the tubings over the wires and the skewer. You may have to cut the skewer to allow space for rotation.

Dab some super glue on the skewer and wire under the tubing and let it run, apply heat to shrink tubing and repeat to other end whilst centering control surface.

Attach two skewers for longer distances or just move the servo closer to the surface and buy servo extensions, and a heaver motor.

It is stiff and light and super diy but perhaps a bit of a chore.
just like this guyhttp://forum.flitetest.com/showthread.php?29359-how-to-make-strong-pushrods
 
#13
Here is a short video of the crash and a pic!
View attachment 75691
What I would do to fix that would be to cut off everything below the horizontal stabilizer and replace a section of each side plate. You probably only need to go about 3-4 inches forward from the front of the horizontal stabilizer. That is the structural part of the aircraft. You may also need to replace a portion or all of the bottom plate if you don't wish to have a seam. Here is the splice technique for joining the patch material to the fuselage. Make sure to double check where you should be using score cuts and full cuts to get it to properly overlap.

IMG_20161014_090809_797.jpg

IMG_20161014_090821_565.jpg

IMG_20161014_090828_845.jpg

IMG_20161014_090838_178.jpg
 
#14
I messed up the whole bevel cut thing and had to tape and use to much glue on the hinges. I just cant seem to perform the magical bevel cut. Josh makes it look so easy, maybe I will try sanding next time...

I also noticed that hot glue doesn't stick very well to the water proof foam board. I'm using the regular white board next time and Minwaxing when done.
The difference between my first build and my second was quite a bit. Practice may not make perfect, but I guarantee it will help. Dollar Tree foam board is cheap. Get an extra sheet and make a couple three elevators. You can practice the "45" and the glue application technique. I have found through experience when Josh said get off as much glue as you can, he really means it. Your finished part will move up and down freely when finished. Keep at it. You'll get it.

Jim
 
#15
I messed up the whole bevel cut thing and had to tape and use to much glue on the hinges. I just cant seem to perform the magical bevel cut. Josh makes it look so easy, maybe I will try sanding next time...

I also noticed that hot glue doesn't stick very well to the water proof foam board. I'm using the regular white board next time and Minwaxing when done.
What temperature of glue gun are you using, and with which type of glue stick? The white foam board will absorb a lot of stuff so make sure to wipe off as much of the miniwax as you can after you have evenly applied it. I would think that if you use the right type of hot glue, it should stick just fine to the water proof foam board. That is what the foam board was designed for after all.
 

nhk750

Aviation Enthusiast
#16
I like the repair method above, I will try that this weekend. My glue gun is the Adtech 100. I purchased it new, but have had problems with it leaking and jamming, making the building process very difficult. I just got a new 200 model that FT recommended and will try that with the next build. I think I did use too much glue. I got the glue sticks from FT, but they were really cloudy, so I just got some from Michaels that are totally clear and will try those next.

I may just build a new fus for the Storch, but will try the repair method first...

One nice thing about where I live is that there are Dollar Trees all over the place and foam board is cheap, probably cheaper than spending the labor trying to repair the damage.

Back to the control linkage rods, I might try his method, but I was worried about all that extra weight from making these. Probably ok on the bigger stuff that has a lot of torque like elevator surfaces, but I will see how the rods bend once I make a good hinge...

I sure am learning a lot.
 
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nhk750

Aviation Enthusiast
#17
IMG_2173.JPG

I did a combination of the above repair and a reinforcement on the tail I saw in another FT build video.
Kind of ugly, but she will fly again!

BTW, my wife says Im addicted to FT build videos...