Stryker F-27C Motor Upgrade!

[akent]

That's awesome, Gabe! I'm right there with ya!

I love this stuff!
Kent

[Gabe]

Got a tip from MoparMyWay on the darkside - as a quick and dirty fix for fluttering ailerons, I painted some 15-min epoxy onto the top and bottom of the elevons. Had to let it dry for 3 hrs though and I ran out of daylight.

He also suggested to lay cf along the trailing edge. LHS only had the flat cf strips. I'm gonna have to get a few hacksaw blades to cut the foam. They have to be laid in like an I-beam with the thin side up. The cf is stronger that way. I'll report back tomorrow with the results.

[akent]

Most interesting!
Heehee!

[Gabe]

Ok, well I solved the flexing problem by laying in the cf tubing along the rear of the plane - not quite on the trailing edges, but rather completing the triangle that the leadin edge reinforcements make. This is the suggested method on the darkside Stryker thread. I also painted the elevons with 15-min epoxy.

Now that there is no flex, all the force is directed at the ailerons, and the flutter is worse than before (straight line). I can't even get past half throttle now. There is some play in the servo horn that may be causing it. They are JR servos so I thought they would be ok. I think it's time for metal gear servos and metal servo horns. At this point, balsa elevons also seem like a must.

[19000rpm]

May 14, 2010 12:13:20 GMT -6 Gabe said:

Ok, well I solved the flexing problem by laying in the cf tubing along the rear of the plane - not quite on the trailing edges, but rather completing the triangle that the leadin edge reinforcements make. This is the suggested method on the darkside Stryker thread. I also painted the elevons with 15-min epoxy.

Now that there is no flex, all the force is directed at the ailerons, and the flutter is worse than before (straight line). I can't even get past half throttle now. There is some play in the servo horn that may be causing it. They are JR servos so I thought they would be ok. I think it's time for metal gear servos and metal servo horns. At this point, balsa elevons also seem like a must.

Yep, something's not tight there. The epoxy should have made the ailerons stiff enough. If you're satisfied the control rods are tight, and not flexing, and the control horns aren't moving then the servos could be the problem.

You might want to also look at the some other HighTech's. They are a nylon and carbon: "karbonite" is what HT calls them. They are very strong, but unlike metal they don't wear out and get slack in the gears like the metal ones do. secure.hobbyzone.com/catalog/HZ/search/HRC33065S.html

[Gabe]

Thanks 19K. I'm gonna see if the Darkside guys can nail it down first. I have a theory that it may be the actual trailing edge itself fluttering. I may add an additional CF spar a few inches offset and parallel to the actual trailing edge.

I've also considered that the cf spar I installed isn't quite flush with the fuse. It sticks up a mm or two here and there. It was my first attempt and it was far from perfect. I'm wondering if the air flow is being destroyed as it passes this area and is causing the flutter on the ailerons.

[Gabe]

Figured it out. Installed the spars along the trailing edge and then I test flew the Stryker and got some sever aileron flutter at 1/4 throttle - but only on one wing. Turns out, the elevon hinge had ripped all the way through on the bottom side on the inner two hinges. After further investigation, I noticed that tears wear starting on the other wing hinges as well. Looks like I need some new elevons. It may not be a pretty fix since some of the hinges had already ripped through the foam and I used CA glue to fix that.

[19000rpm]

LOL, I thought abut the hinges after my last post and then promptly forgot to post about it. ;D

Anyway, you figured it out.

[Gabe]

Yup, bought enough balsa yesterday for the current Stryker and my new darkside build. I will probably use the current Stryker as a test run for the balsa elevon construction, that way if I screw it up I won't be pissed.

[Gabe]

Well, since I had CA Glued the elevons and retainers to the trailing edge of the wing, upon removal this happened:



I was gonna retire this Stryker, but after a conversation with Gryphon from the Darkside, he mentioned a little balsa glued in there would do the trick. He also said I should run a strip or two of Xtreme Tape along the trailing edge to hold everything in place.

The flutter, according to Gryphon, is caused by the gap in between the trailing edge and the elevon. A little hinge tape would have done the trick. So next week, I'll paint the new elevons with epoxy again, stick some balsa in the holes, lay some Xtreme Tape along the trailing edge and some hinge tape between the elevon and the trailing edge.

Sounds simple right?

[19000rpm]

I can see how that happened. The faster you go the more you need a clean airflow.

[Gabe]

Well, I decided not to fix the original Stryker after all. I just paid the $25 for a new fuse and elevons. I'm just gonna switch the electronics over. Everyone's ou of the cf tubing so that will have to wait a few days till my shipment comes in.

In the mean time, here's a look at the new paint job. Still got one wing and the vert stabs to paint:

[19000rpm]

Another great paint job Gabe. You've really got an eye for this stuff.

[akent]

That looks AWESOME, Gabe!!!

Painting FLAMES already?!?!?!?

Yeah, those airframes are really super cheap. It's really amazing.

I'm jealous!
Kent

[Gabe]

Here's the final build on my first generation Stryker. I still haven't installed the CF tubing on the bottom yet, I'm waiting for it in the mail. I also used hinge tape on the top and bottom of the elevons to eliminate the aileron flutter - its gone completely now.

I had the bottom painted candy apply red, but it was too hard to see in the sky so I slapped some yellow on there. I'm waiting for it to dry to test out the visibility again.

The tape I used along the leading edge and over the servos is called Extreme Packing Tape. Its at Home Depot and the Darkside guys all suggest it.

Also, I forgot to purchase the two little holders for the vertical stabs so I ended up hot gluing the stabs in there. They didn't budge on the first flight, and I doubt they will.








Thanks for all the encouragement guys! This was a fun one!