x00% FT Arrow, or some other new design?

Tench745

Master member
Anyone put together a larger scale Arrow yet? I've been enjoying my Blunt nose versa wing, and thinking it needs a few tweaks when I finally smash it to bits. I'd like a thicker chord to the center section for full size 2200mah batteries and a way to mount the motor further forward for better balance.
The Arrow seems to do both of these, but its reputation for a weak center section, and its general appearance doesn't thrill me. Nor do I like the thickness of the center section on the arrow where the motor mounts. Thoughts, opinions? I know my versa, but not the Arrow.
I'm looking to build something even lower drag than my versa, smooth, fast, and clean. Maybe I'd even glass it. I'm not willing to throw more power and weight at a draggy airframe to make it faster (the arrow seems very draggy to my eye.)
I guess I've talked myself into some combination/modification of the Versa and a larger Arrow rather than any one alone.
Structurally, the Arrow has about 10degrees more sweep to the wing than the versa, giving it greater yaw stability. I think if the wingtips extended and tapered to an elliptical tip, you may not even need vertical fins. (Merely conjecture)

So, summary: Anyone tried a large scale Arrow? Anyone want to discuss the aerodynamics of flying wings? Anyone want to collaborate on a speed/soaring wing?
 

Bangle

New member
I have designed a scaled up twin arrow with the exact same wing span as a blunt nose versa. I went twin motor as it makes all the components interchangeable with our modified mini arrow, two tiny trainers and two nutballs (we fly as a couple!). Differential thrust looked fun too, though I have yet to test it. It fits a Turnigy 2200mah 3s lipo.
The design flies well, but I had a motor cut out, as I'd used under-sized ESC's. It went into a nice spin after I had a bit of a fight with it and it landed flat and relatively soft so I suspect differential trust will be effective on it. I've spent a few weeks modifying the mini arrow to fly with down-thrust (a huge improvement). Now I will incorporate the set up into this larger wing.
The idea was to have a bigger and slower wing, which cruises. It does this, but will go like hell too!



I will happily email DXF files to anyone interested, just PM me
 

Tench745

Master member
Bangle, I like the dual pusher arrow; it makes great use of that huge prop cutout. What's that about 14"? The dual is a great way to get the thrust without swinging the monster prop that would fit in there if you chose to, but no one could ever launch it without loosing a hand. ;)
So, I plugged both the Versa and Mini Arrow into autocad. Looks like a 130% arrow would have the same wingspan as the versa and is 1/4" thicker with just enough room for a 2200mah. If you threw a center section in on it like the versa I think it looks goofy with that huge cutout. So I redrew some things:
On the left is a blunt nose Versa. To the right of that in magenta is the Mini Arrow. The green is a 130% Arrow.
The blue thing all the way to the right is that same 130% arrow with an 8" center section, minus the cutouts, and with the wingtips extended into an elliptical shape. I'd like to build a wing that can fly without v-stabs, but I don't know if this is possible.
Wings.PNG
 

Bangle

New member
The cutout is 17 inches. I had accounted for a possible need for larger props, but 6x4 on 2204 motors is fine. I took the twin on a flight this morning in 18 mph wind. It flew pretty well, but I botched the landing. I started to flair a little early and a gust flipped me rather heavily into the ground. the battery bust through the spar compartment and ripped the wires out of one motor. We paired up and spent the morning fixing it, and now it is ready to go again. When it did fly, it had a great glide slope and the 4.7degree down thrust made a world of difference. It also makes a real screaming noise as it flies
The picture is of my scale comparison between mini arrow, blunt versa and my concept. (I am also happy to share my DXF files with you if you want them) We are about 3 months into this hobby, and find the fin ends make for more crash resistance, which we both need. They rip off cleanly and are easy to replace. As for extended wing tips, I can't see why they shouldn't work. It seems a common mod on versas and several slope soarer designs are fin-less. I did fly one mini arrow once with a missing fin with very little difference.


Arrows and versas.jpg
 

Bangle

New member
Update:
Flew in 20mph winds with differential thrust set at 30% in a way where one motor throttles down as the other throttles up. I can report that it flat turns so well and flies very like a conventional 4 channel with plenty of yaw authority. I didn't get to test 100% differential thrust, but based on the loss of a motor on an earlier flight, I suspect 'crazy mode' would work.
Unfortunately, i flew into the sun and had a perspective fail, as the top and bottom patterns are similar. I hit strait down at a lot of Mph and totally destroyed the plane. The wires ripped out of one motor beyond help. My wife has just reattached the wires to both servos and the battery is very bent and sat outside in saline solution.
Oddly enough, we are very happy. The design is proofed, and differential thrust works on a wing with pusher props.
Pilot error due to inexperience, the sun and poor colour scheme is neither here nor there. Bit of a shame about the battery, which was quite new, but all in, another twin arrow will set me back about £18. This demonstrates what I love about the self-build element of this hobby.
Now time for a new one!

Here is a photo of the carnage:
 

Tench745

Master member
Sad to see a new plane get trashed, but always rewarding when an idea works. :) Can't wait to see the next one Bangle. I want to build a new wing but I just can't seem to kill my Versawing. Even today, I was performing a full power dive, the motor mount broke free and snapped the prop at full speed maybe 20ft from the ground. Even out of balance and power-off it just glided down and settled at my feet. The thing's like an obedient puppy; full of energy, but always ready to go home with you.
 

Tench745

Master member
I was going through my list of planes in my hangar and realized that I never updated this thread when I finally build a replacement for my Blunt-nose Versawing. I ended up mashing together my favorite things about the Versa and the Spear into something I called:
The VersaSpear. (McB VS for short)
IMG_0433.JPG IMG_1055.JPG

I used wing panels from the spear, and borrowed the center section heavily from the spear. The wing has no dihedral, the elevons are full span, and there is a chuck of poplar that runs from the wing spar into the center section's box-spar. The center section is about the same dimensions as on the Spear, but the chord isn't as thick. I did have to add some lead in the nose even with a 3s 2200 all the way forward to get proper balance.
This plane is great, tracks straight and flies well even inverted. I loved it and flew it a few times at FTFF'17 when I was nervous to fly anything else.

This winter I was flying with my brother and the prototype we were testing didn't last long, thrust-line issues. I had brought the VS along to have something reliable that always flies well so we didn't waste a trip to the field. I had a twitchy servo when I did my control check on the VS but decided that it wasn't time to go home yet and I would risk a flight anyway. I realized that was a bad choice almost as soon as I got into the air. I almost made it back for a landing, but had limited control and found a tree on the way down. I stripped both servos and crumpled the nose a bit. It was fixable but I decided I could do one better next time so the VersaSpear was retired for the electronics. On tearing it apart I found out that I had used Hobbyking's HXT500, 5g, servos. This plane is too fast and the elevons are too big for servos that small, so the next one will use 9gram servos, possibly metal gear for reliability.