Yardbird F-22 With K F Airfoil

[mumblinaviator]

I installed 4mm foam K F Airfoils on the upper side of the wings on my YB-22 to see if I could cure its Pitchiness that is so common to flat wing foamies.

It WORKED! It's much more stable at slower speeds, and the AOA was reduced by at least 10*. Turns are easier and more stable... Basically it handles better in all flight regimes.

Just putting the info out there in case anyone was curious or interested. Pics soon to follow!

[Louis]

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[mumblinaviator]

Right now the step is only as thick as the foam piece I laid down. So about 5mm. I'm thinking of raising the step a bit as suggested by many KF builders.

Right now the Dimensions are 15" x 11.25" x 1.5" x 7.75", and yes I did bevel the leading edge.

All of the measurements were a guess on my part as to how it would work, I just eyeballed what I felt was about 50% of the chord, which is hard when working with a delta. But as I said before, the results are great! I'll test more and post again after I've raised the step a bit.

And yes, the white foam isn't very tactical for the F-22, but it helps tremendously with orientation at a distance.

Enjoy!

[Louis]

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[mumblinaviator]

Get off your duff?? Heck, this thing builds so quickly you could probably accomplish it in one Sitting.... literally!

It flies amazingly well, with or without the KF. You'll enjoy it.

[Louis]

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[mumblinaviator]

^agree about the glue. I've gone strictly to CA and 5 min Epoxy. Even w/ 5 min I have enough time to work the pieces into place if necessary.

In regards to your mods: The support rods from front to aft aren't necessary. The ribbing that's built into the body (both underside and topside) effectively keep it quite stiff in that direction. As for the Elevons, they have plenty of control authority as is if you'd rather not go through the hassle.

Goodluck, have fun!

[Louis]

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[j4ck4]

Hey Mumblin
I've built several F22's with the kf steps and love them. I've gone totally to hotglue on my F22 builds though makes the build a lot faster, and from what I've seen just as sturdy as ca gorilla or epoxy. I mean why use epoxy to mount a piece on a foam plane if the foam is going to tear out in a crash. Hot glue will rip foam out in most instances if you hit anything hard enough that it is going to tear parts loose. Love the build.

[mumblinaviator]

Glad to see the thread has been moved to a proper Forum!

I've put dozens of flights on the 22 since the last posts and it's still going strong. I replaced the harsh white step with Grey 6mm Depron. Same flight characteristics, but w/ a more tactical appearance. It's harder to maintain orientation in flight, but I've had enough flights with it to have a decent "feel" for where it is.

I'm leaning more towards Hot Glue lately, especially for the quick profile type builds, or for areas that need a quick fix. It's heavier than I'd like in most circumstances, so I use it sparingly, but it works great.

Yardbirds Foam Glue is great if you have the time to let it sit for 6 hrs to cure properly... it's strong and lightweight and won't rip away as much foam as hotglue or Epoxy.

[j4ck4]

Thats true I just built 2 yardbirds for FB's the Ultimate Foam Glue from yardbirds is a really good glue. I finally figured out that is almost a contact adhesive type of glue, apply it to one part, stick them together and get good coverage on both pieces. Pull them apart and let it tack for a few seconds or even minutes stick them together and you can barely move them if needed for alignment purposes. Great glue.

[crxmanpat]

I like the Yardbird glue too. What I typically do is put a thin layer on both parts to be joined, mash them together for a second then pull apart again. Then I take my finger and smooth out the glue line and let it sit for about 2 minutes to get tacky.

Once the parts are pressed back together they are almost not going to come apart. I'll usually glue up an entire plane in a single sitting, put some low tack painters tape where needed, then let it set up overnight to fully cure.