Hello! Explorer build

docque

Active member
I built two Explorers and loved them. Both had the issues you talked about (folding wings and tail heavy). I was told that a simple solution is to cut the boom shorter. I haven't tried it because I have other planes I enjoy.
 

rmzalbar

Member
I built two Explorers and loved them. Both had the issues you talked about (folding wings and tail heavy). I was told that a simple solution is to cut the boom shorter. I haven't tried it because I have other planes I enjoy.

I actually tried this, initially. I shortened the boom by shoving it in as far as it could go. This did let me use less weight in the nose, but the plane flew better with a long boom - the reduced leverage meant more trim was needed, which meant more drag, and it was more pitch-sensitive to thrust/throttle.

It wasn't enough, though. I would have had to make it shorter than I did for full compensation, and already wasn't liking the characteristics of the shorter boom. Lengthening the nose cone and tray was definitely the better way to go, and really not much work. I sliced off the tray and spliced in an extension piece, and since I had to replace the nose anyway due to a crash I extended the tracing by 3 inches. I have no lead ballast now, plenty of room for camera stuff, and it flies great.

Here's a photo with the longer nose (and casts/bandages/scars from a crash)
 

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rmzalbar

Member
Okay: New triangulated wire landing struts, axle wing, and horizontal stabilizer. Also, a bit of downthrust added to the power pod, as mentioned before. I placed the wheels a bit further forward of CG to help reduce faceplants. I don't think it will hinder takeoffs with this thing. I also set a low rate profile to make it easier to handle under power. The balance seems to be just about perfectly neutral at the top wing fold, could always add a tiny weight up there if I need to. Guess I'll find out Saturday morning.

20181221_002235.jpg 20181221_002222.jpg 20181221_002249.jpg
 

rmzalbar

Member
Went to the field this morning and (most) everything went very well! Setting the balance neutral was the right thing to do. It made takeoffs and landings possible, and reducing my throws tamed it enough to get me some good stick time. All my landings were wheels-first and while some of them rolled up on the nose or looped, this got better as I learned to add more back-elevator to pin the tail after touchdown. Takeoffs got better too with practice, with less ground-looping, with longer rollouts to genuine tail-lift, followed by a normal roation to takeoff. It's still squirrelly, but manageable and it rewards gentle input with smooth patterns. No crashes, way fun!

Also took the Explorer for a walk with both wings. Smooth sailing and gentle landings there too. Maybe I'll go out in the morning again
 

Headbang

Master member
Went to the field this morning and (most) everything went very well! Setting the balance neutral was the right thing to do. It made takeoffs and landings possible, and reducing my throws tamed it enough to get me some good stick time. All my landings were wheels-first and while some of them rolled up on the nose or looped, this got better as I learned to add more back-elevator to pin the tail after touchdown. Takeoffs got better too with practice, with less ground-looping, with longer rollouts to genuine tail-lift, followed by a normal roation to takeoff. It's still squirrelly, but manageable and it rewards gentle input with smooth patterns. No crashes, way fun!

Also took the Explorer for a walk with both wings. Smooth sailing and gentle landings there too. Maybe I'll go out in the morning again
I got my Explore out last week for a maiden, went well. It flew a little tail heavy, not a big deal for me, but I can see how making the nose a few inches longer would help with battery placement to tame things down. Maiden video to come sometime over the holiday (need to find time to do final edit)
 

buzzbomb

I know nothing!
Oh, but heck yeah! That's an awesome maiden. She looks good, she flys good. "Doesn't like upsidedowness, though?" I've gotta go look that one up. :p
 

rmzalbar

Member
Got the video done!

Last Tuesday maiden of my completely stock, scratch built, FT Explorer

That looks great and looks like it flies very well! Your build is lighter and indeed it looks like it climbs better than mine on the sport wing. I see you built your wing straight across. With the dihedral in mine I have a hard time telling if it's rudder or aileron trim I need, because roll and yaw are so strongly coupled. I would like to try another build for light weight, with a straight across Armin wing. If I fold up the tail boom too badly on this one, I might try making a twin-tailboom with cf tubes, or arrow shafts. That may allow me to use a 10 inch prop for a little extra grunt.
 

Headbang

Master member
There is a few deg of dihedral. Only bracing is tape the full length of the wing top and bottom. Came in at 750g with battery, so it is light thanks to white gorilla glue. It is under powered for loops and such. I found I had to use rudder a lot to kick it around turns. Didn't think about it at the the time, but I can see myself kicking the tail around in the vid. I will be dialing this one in and setting up a buddy box for training others on it this year, that was the main goal.

If I were to do it again, I would also do a straight wing with a spar, lengthen the nose 2", raise the motor pod a half inch and make the rudder larger. And I might do all that except the rudder anyways on this one.
 

rmzalbar

Member
There is a few deg of dihedral. Only bracing is tape the full length of the wing top and bottom. Came in at 750g with battery, so it is light thanks to white gorilla glue. It is under powered for loops and such. I found I had to use rudder a lot to kick it around turns. Didn't think about it at the the time, but I can see myself kicking the tail around in the vid. I will be dialing this one in and setting up a buddy box for training others on it this year, that was the main goal.

If I were to do it again, I would also do a straight wing with a spar, lengthen the nose 2", raise the motor pod a half inch and make the rudder larger. And I might do all that except the rudder anyways on this one.
It's a really good plane for training. Especially with the 3-channel wing, it braves the wind, climbs high, glides great, flies hands-off and lands like an autumn leaf. Very gentle characteristics. Big enough to be easy to see when you go far out. Hand launches would challenging for a beginner at first, although that snow pack seems to fix that problem :)
 

rmzalbar

Member
I've been flying the Fokker a lot over the past couple of days. I live on a hill, so I have a great view of the area and a large "bowl" to fly in. There were a tense couple of minutes when I flew it so far away, that when I thought I had it turned toward myself to return, it was actually turned away, so then it became a featureless speck and then I could no longer tell which way it was headed. I maneuvered to kill its lateral motion, then had to wait.. and wait.. to see if it would expand beyond a point. Eventually, it did. Next time that happens I should remember that if I see it moving left or right, I would then know which direction it needs to turn a 90° to come toward me.

Landing is still a disaster as the wind is always blowing straight up the steep hill I live on. I'm down to my last propeller now, and that one is a 5.75" prop at this point, with all the tip-chipping and filing/balancing to compensate. Landing up a hill into a tailwind.. not fun, but a good skill to have if I master it :)

The few deg. of downthrust I gave to the power pod probably helped, but it isn't enough for that F-pack motor. Full throttle on that sucker just makes it go into an endless series of loop-the-loops, unless you counter it. I don't think it's reasonable to try to tune all that out with downthrust, though. The fact is it's an undercambered old lady with a 2:1 thrust ratio.
 
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