Stryker F-27C Motor Upgrade!

[19000rpm]

Extreme packing tape is a great idea for the leading edge.

Visability with the yellow tips should be very good.

[Gabe]

Yup, it helped a ton!

It really needs the cf tubing though. At WOT she has some torque roll. Need to epoxy the elevons and throw some stronger 2-56 pushrods in there too like 19K suggested. Just running the 3S for now till I get the goods installed.

[Gabe]

Got the CF tubing in today. Only put in the "left to right" spar, and didn't really feel like replacing the stock spars along the trailing edge yet.

I also put in some of the DuBro 2-56 pushrods with Kwik Links.

Man, what a difference that makes. I can almost run WOT on a 3S comfortably with the 6x5.5 prop now. There's still a small amount of torque roll - but I can counter most of it now. I think 19K was right and it was the pushrods deflecting/bending.

Also, I noticed a small crease in one of the elevons after a few flights at WOT. That leads me to believe the torque roll is stemming from the elevon now. With the trailing edge stiffened up, all the force is directed to the elevons - so I'm gonna go ahead and epoxy them tonight.

I also ran a few 4S today but really didn't feel comfortable with the controls. The Stryker is really nose heavy with the 4S and there is a lot of torque roll - which I'm still able to counter - but flying isn't comfortable.

OK, epoxy on the elevons and CF spars in the leading edges, coming up!

[19000rpm]

You're doing a great job of chasing down the weak areas. Weak areas are like gremlins; just when you think you got rid of one it jumps to another area. ;D

That thing must be scary on 4S. I think you made a good choice by grounding it and going with the other mods before something went terribly wrong.

[Gabe]

Well, it seems I created a slippery slope with this whole thing. The elevons now flutter tremendously and I actually ended up tossing her into a building on the launch. So I ran a CF Spar along the trailing edge in hopes of making it stiffer. That didn't do anything except weigh down the rear of the plane. I couldn't figure out why she kept face-planting on the launch until I checked the COG. I added some weight to front and now she flies pretty good (except the flutter). Had to also stick a 4S in there to add weight.

I'm not convinced the flutter is from play in the servos. That's the only remaining component.

[19000rpm]

Those frickin' gremlins! Can you safely bench test it to see where the problem is? At least that way you might be able to see if it's mechanical or eliminate that and work on aerodynamic issues.

[akent]

Well, I launched my Stryker today for the first time in a few weeks.

Uh, well, uh, the wing hit my head when I threw it and it went inverted and then I got control of the sticks and then I hit the WRONG thing.

Poof. I saw chunks-o-foam flying and in the middle of that, and a blue thing that resembled a battery was flying at really fast speeds away from the crash site. There were slow motion folks in the background going, "Oh" too.
I felt like a complete idiot as this was at the flying field in Austin with lots of folks around.

Oh well. I already have the airframe for the DARK build! I may though have to use it to get back to being able to fly this thing.
There were two other Strykers at the field today, but they were both stock. It would have been really fun to show off!!!!
Kent

[Gabe]

OH MAN! How did I miss this post?!

Sorry buddy. I know how ya feel. Just tossed mine into a building the other day (see above).

Well, on a separate note, I was having issues with the power cutting out mid flight. I wasn't sure if it was the ESC or the motor, so I decided to use some batteries I had laying around - 3000mah 40C Zippies!

I put the spare 80amp Hobbywing ESC in there too just for safety's sake. There was a lot of hollowing out to do in the battery bay. She's pretty nose heavy and there's still flutter, but I don't care at this point. The Darkside Build is getting close. The motor finally shipped this week!

Won't be long now boys...

[19000rpm]

Sounds like you may have had a loose wire causing the cut out. I've had that happen in a few of cases. Once at the battery, another time at the ESC and twice at the connectors. A little too much vibration or too much heat and you get sudden silence. Not the sound you're wanting in mid flight. ;D

Look forward to both of your Darkside builds.

[Gabe]

While I was waiting for the Darkside build parts, I opted to try my hand at glassing the old Stryker. Laid down some cloth and used the Polycrylic Minwax with a 1/2" brush. She's been curing for about an hour. I'll keep ya'll updated.

[Gabe]

Lots of stray "hairs" when I trimmed it with scissors so I trimmed it with the hobby knife when the acrylic actually bonded with the foam. Its a much cleaner cut. Gotta try wet sanding now.

[Gabe]

OK boys, I wet sanded her, let her dry and threw some hinge tape on. Total weight without the battery was 1.107 lbs. With the Zippy 3000 mah = 2.6 lbs. The battery weighs over a pound!

TEST FLIGHT RESULTS:

I need a nice clear, long path to toss her, as she takes a moment to build up thrust and lift. I'd say 30-50 yards. I have the elevator stick pegged and she gets going a little sluggish. I may need to try a 7" prop (not sure if the motor can handle the amps though - need an amp meter too).

Did a few passes at half to 3/4 throttle with no issues and no flutter - then I opened her up for a high speed, WOT pass...NO FLUTTER!!!! Solid as a rock and turns on a dime at WOT. She comes in REALLY hot for the landing though. I used about 75 yards of 8'-10' off the deck to slow her down and about 300 yards total for the landing.

I'm pleased - at last! 'Nuff said.

I'll paint her tomorrow and get you guys some pics.

[19000rpm]

Awesome. Probably could use a slightly bigger prop to get a bit more initial thrust. Look forward to the pics.

[Gabe]

Yup yup - I talked to my Darkside boys and they said a 7" prop is the way to go. Gotta order one once I figure out what pitch I need.

Here's the pics of the paint job. I still need to paint the elevons (probably chrome or black) and touch up the drips on the nose:

[akent]

NICE! I really like the color contrast. It really should be easy to see the orientation in the sky!
Kent