|Jul 24, 2012, 11:46 PM|
I dont think it was a stall, it had plenty of speed and throttle. Too much throttle I think.
I know some other guys have flash planes but I started this hobby about 2 years ago to get into FPV. I started with the Heli then went to the Bixler and now this is the pride of my fleet. The Heli now flys 3D, the AXN and Falcon wing park fly, I have a FunJet that I built with ridiculous power that I have not yet been game to fly, there have been many Park Jets destroyed in practice for the Fun Jet and the SW has well over $1000 invested from the Ground Station to the plane. For $84, I want it to be the best it can so I'm ordering another.
Here's the ground station recording. It's all staticy because I was flying LOS and hadn't even worried about putting the antenna up. You can here the motor running pretty hard but my Castle ESC log only shows a peak of 25amp and mostly about 20amp. If you can see throuh the static, I had a reasonable amount of speed on and I had hit RTH. It's Dragon OSD which only controls the surfaces when the sticks are centered so I still had control.
Here is the flip from the previous flight.
After examining this flip some more, it seems the flip only happened at high speed. I was gradually pulling up elevator with no effect and then all of a sudden it fliped. Then it was nose down and diving but much slower after the flip and I was able to pull out rather quickly.
|Jul 24, 2012, 11:46 PM|
Joined Apr 2012
AXN's seem to be embarrassingly indestructible. I thought I destroyed mine, ordered a new one. Got sick of waiting for HK and decided to rebuild it. It flew better than before, not before new but before I had many crashes, broke the wing a few times, tail off a few times etc. Now its nearly better than new.
Now since I have 2 I'm going with a 600Watt engine and 4S battery and see what it can do.
I'm sure the Skywalker is not as robust, hopefully I will finish my 1900mm version shortly for LR FPV.
|Jul 24, 2012, 11:48 PM|
That crash could have been due to a lot of things, but I doubt very much
that it had anything to do with flexy tail or horizontal stab as very
few people have broken the tail in the air.
And the SW doesn't do "flat spins", unless the wing is broken in the air,
or separated from the fuse (due to not using all the rubber bands properly).
How are you using your four rubber bands?
Frankly I've never seen a SW flying in such a messy state.
The SW doesn't like vertical dives as the wing's high lift airfoil generates a strong
forward pitching moment and it may try to pitch forward in a vertical
dive so much that there's just not enough elevator authority to pull out,
but it doesn't look like that's what happened here either.
That might have been problem with previous flip.
Was that SW even FPV piloted? Most folks don't fly that "hard'
while FPV piloting, since you just can't see where you're going
when you yank and bank that much. I see in
reply a moment ago, that it was LoS. That explains the general
discombobulated starting attitude. FPV piloted, this probably
wouldn't have happened. This plane will do acro (loops, rolls, inverted), but it is
not a 3D plane, and shouldn't be treated as such.
|Jul 25, 2012, 02:43 AM|
Only a small fraction of OSDs have an artificial horizon and could
have indicated the fact that a steep bank had turned into a steep dive.
RTH wouldn't have helped unless I knew I were in trouble, which I
didn't until I heard the plane hit the ground 100 yards away.
The lesson I learned from it, was make sure to only fly places with
lights visible in all directions which has worked quite well.
I still don't fly with an OSD or RTH at night.
|Jul 25, 2012, 03:35 AM|
|Jul 25, 2012, 04:09 AM|
Thanks for telling me my SW flies really bad. I didnítí know. LOL.
I went to my usual test area but there was an event on there. I had tested RTH there before and know I have plenty of space to fly. I was a bit disappointed that I couldnít fly there as I had loaded a waypoint route of about a 500m square. I in Canberra, Australiaís Capital City and I donít like to fly too far away around here as if something went wrong, Iíd be struggling to get my plane back. The place I flew this time was close by but I donít know anyone in the area. My usual FPV place is 3 hours drive away and my mate who lives there, is in Japan at the moment.
When I couldnít fly my usual test area I should have just gone home but I had a friend with me as a co-pilot and I was as excited to show him as he was to see it.
At no time did I fly it upside down but I did fly pretty fast and in a pretty tight banked circle. Thatís it. I levelled out and pulled up elevator and the next thing it rolled upside down, I used ailerons to roll back right way up and then it nosed down and spiralled into the ground. I could have possibly corrected the spiral had I had enough height but I just want to know why it happened in the first place?
|Jul 25, 2012, 05:07 AM|
Further to last.
I am unsure if this happened in flight or as a result of the crash but it supports what I thought about the HS lifting.
When I was picking up the pieces, I noticed this little bit of slack in my Dragon Link Antenna wire.
(see pic 1)
I didn't think much of it at the time.
Then I noticed the indentation in the foam from the HS retainer.
(see pics 2 and 3)
The the retainer had only indented the front and not the rear.
(see pic 4)
Then I found the HS had come away from the VS. It was still firm but had obviously lifted at some stage. I had glued this when constructing with some glue left from my Bixler. I didn't glue it for retention strength, just to ensure a perfect fit with the HS level with the main wing. Note: I am applying some pressure for this photo.
(see pic 5)
Then I found moving the HS like this
Caused the slack in the Dragon Link Antenna wire like pic 1. The HS wont move vertically on the air frame near enough to cause the wire slack, it needed to twist heigher on 1 side, the side with the antenna.
(see pic 6)
Note: I am not a gorilla, I'm just a bit hairy.
|Jul 25, 2012, 06:37 AM|
|Jul 25, 2012, 06:44 AM|
Those came with the older SW's, I like them more as well,
"(see pic 6)
Note: I am not a gorilla, I'm just a bit hairy. "
|Jul 25, 2012, 09:13 AM|
Taking time to install FPV components correctly and good flight preparation are still the best insurance that you will bring back your plane whatever the equipement in it.
|Jul 25, 2012, 02:29 PM|
Regarding the recent mis-haps...here's my two cents:
- AHI and especially OSD are huge helps with night flying. It is easy to get disoriented with where you are and a bit with attitude too. Many times at night and even sometimes during the day in a new area I relied on the ETOSD "RADAR" to guide me home. The AHI is a huge help too and works with RTH to ensure a stable flight back home.
- Stabilizing the main and tail is a good idea if you're going to be hard on your SW or are heavy and fast...here's what I've done that has successfully and fully strengthened the SW:
- 1-2 wooden spars across the top full length of each main wing half (use a solder iron to melt out the channels)
- At least two full wing length strips of fiber tape across the bottom of each main half
- vertical CF tube down the full length of the vertical stab and into a drilled hole in the boom CF tube...epoxy the connection outside and in the tube as well (this is important because otherwise with use the connection will stretch and become less effective)
- horizontal CF tube from front to back across top of the vertical stab to keep the back of it from pitching backward and forward (you'll have to put it on either the left or right side as there's no room down the center.
- thick and short CF tub underneath and tight up against the bottom of the wooden screw-down plate...to keep the plate from tilting side to side and for extra lateral stability at the top of the vertical stab
- flat wooden spar across top of horizontal stab (1.5in x approx 6in)
- two short (approx 1/2in aluminum spacers epoxied to the bottom of the horizontal stab up against the bottom of the wooden spar that goes across the top and aligned with the screws (ie screws go down through the center of the spacers) This allows for a rock solid connection to the vertical stab wooden screw plate when tightening down the horizontal stab.
- two CF tapes (1/4in) vertically placed to the left and right of center running the full boom length to keep the boom from twisting...this is necessary because as you fully stabilize the tail all of the tension occurs in a twisting of the boom.
It's a lot but it's worth it. Of course there's a lot of added weight but who cares if your running a decent motor
|Jul 25, 2012, 03:11 PM|
wire slots is actually still nose heavy. On a conventional aircraft balanced for
stability, the CG is always in front of the center of lift of the wing. This means
weight ahead of the center of lift is pulling the nose down (which I'll
call "nose weight" even though it has little to do with the nose, while
the horizontal stab has to generate downforce (negative lift) to to push
the tail down to offset the nose weight. A nose heavy plane requires
more downforce be generated by the horizontal stab to balance it.
A true tail heavy plane has the CG moved back behind the center of lift, and
it would require the horizontal stab to generate positive lift to hold itself up.
True tail heavy condition is severely unstable because the plane will
pitch down as it speeds up, and pitch up as it slows down which is
The stock CG location at the wiring slots is severely nose heavy.
15mm behind servo wire slots is still nose heavy. Getting
back around 25-35mm behind servo wire slots is closer to optimal.
At that point, CG is very close to center of lift, and the horizontal stab has
to generate *very little* downforce. In other words, it works less hard,
and is less prone to flexing during normal flight.
However. As I mentioned, in addition to the balance of nose weight
and downforce, all non-symetrical airfoils have some forward
pitching moment. As they generate lift, they're trying to pitch forward.
This forward pitching moment has the same effect as nose weight
and thus must be balanced with downforce from the horizontal stab.
But the magnitude of the pitching moment changes with airspeed
so you can move the CG back to optimal, as long as you keep your
airspeed in check. If you overpower the plane, or put it into a vertical
dive, the forward pitching moment will be so strong it overwhelms
the elevator (bends the foam surface itself) and you may not be
able to pull out, until you slow down. If in a vertical dive, pushing out
inverted may be the only way to recover. Best just to not get it
into that condition.
badly. It generally flies itself, just fine.
departure of the horizontal stab, which leads to sudden increase in
angle of attack of main wing, and tip stall to spin), but my SW has *never*
done that and I fly it very hard. How much elevator throw do you have?
It would take a massive amount to induce a stall in the stab, but it's
possible. As you move the CG back, you must reduce the elevator throws.
|Jul 25, 2012, 03:20 PM|
and I've found it to be very slow to respond to sudden changes. I was only
flying about 100 feet up, so it'd be hitting the ground about the time
the OSD started to indicate a large altitude drop. I have an OSD on
my X8, and see this lag all the time. I've done a fast vertical climb
and then waited 4-5 seconds for it to *start* to indicate a 300-400 foot
For whatever it's worth, this is what I was doing flying in the dark
in rural Kansas.
Everything was perfectly fine as long as the fireworks were going, but then
their torch went out. All downhill from there (not shown in vid).
All I needed to stay oriented were a few lights on the horizion, but
they just weren't there for most of the circuit.
|Jul 25, 2012, 03:23 PM|
with 10Ah worth of battery, and some have probably done
quite a bit more than that. Some folks also build very heavy. The main limitation
with a heavily loaded SW is not the flying, but simply launching it fast enough
to get flying.
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