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Jun 08, 2010, 01:49 PM
Houston. .we have a problem.
FOX ONE!'s Avatar
Anyone flown their birds recently?
Last edited by FOX ONE!; Jun 22, 2010 at 11:42 AM.
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Jun 23, 2010, 08:53 AM
Registered User
hklagges's Avatar
Quote:
Originally Posted by abagnalejr123
Anyone flown their birds recently?
Check out this guy here:
http://www.xwing-crew.ch/index.php?o...86&video_id=34

Cheers,
Henrik
Jun 23, 2010, 09:11 AM
DJI Supporter
Sid3ways's Avatar
LMAO, who needs a dolly when you can take off on the gear and jettison it after takeoff?
Jun 23, 2010, 10:02 AM
Registered User
What the hell happened there? Why did it dip so much after take-off?
Jun 23, 2010, 10:26 AM
Registered User
hklagges's Avatar
Quote:
Originally Posted by Jammo
What the hell happened there? Why did it dip so much after take-off?
Probably overcontrolling... with all these control surfaces the Su-47 is incredibly agile.

Cheers,
Henrik
Jun 23, 2010, 10:56 AM
Registered User
Makes sense.
Jun 23, 2010, 02:35 PM
DJI Supporter
Sid3ways's Avatar
Looked like it needed an insane amount of trim and the elevators/canards weren't at the right neutral angle to begin with. Either that or he put a cinder block under the canopy.
Jun 30, 2010, 03:48 AM
Registered User
Awesome with the cow's bells in the back

It gives a godd idea of switzerland lol
Jun 30, 2010, 06:59 AM
Fly, crash, fix, repeat
f4addict's Avatar
Mtn_commando, how did your maiden with tuning gyro's go?

The guy in the video was trying to loose some weight off the plane so instead of doing all the hard word, he found a easy method. Just rip the landing gear and doors off.!!!:-)
Jun 30, 2010, 08:17 AM
Registered User
Mtn_Commando's Avatar
No maiden yet, been unable to find time. Will post a report as soon as she takes to the air.
Aug 01, 2010, 01:55 PM
Registered User
Mtn_Commando's Avatar
Ok gentlemen, I finally maidened her yesterday. The delay was because I was looking for a paved runway. I finally joined a club that has one.

Actually, I had cold feet so I asked one of the field experts to maiden her. AUW was 2750 grams. All gyro gains were at 0%, and thrust vectoring was kept off.

First takeoff was aborted because she ran out of runway (around 100 feet). Ran into the grass and that caused the front retract to dislodge. With some 5 minute epoxy, she was ready to go again.

Second takeoff, we started right at the beginning of runway, allowed her to pick up good speed and lifted off like a rocket in around 150 feet. VERY tail heavy, said the pilot! Also very touchy on the controls. We knew immediately that we had to bring her back down, the pilot was struggling to keep her under control (and he's a GOOD pilot). Power was enough, but it was way tail heavy and that made it very hard to control. Easing back on the throttle caused her to nose up dramatically, almost looking like a cobra .

Anyway, he was finally able to get her down. Landing was a little rough, she came down almost vertical on her tail. Thrust vectoring nozzles dislodged and both of the rear retracts snapped right at the wheel. But the rest of it is unscathed.

So, looks like I overcompensated for the CoG. I had it at about 3.5-4 cm (so 1-1.5 cm behind factory setting), and that was definitely too much. On a positive note, the repairs are easy. Looking forward to getting her back in the air next weekend. I'll be extra careful to keep CoG exactly at 3cm.

She was definitely a head turner though
Aug 01, 2010, 02:09 PM
Flying Hazard
SU-4ever's Avatar
I'd have used the gyros.

That's the trick on Tail heavy planes!

Good to know it lives to fly another day, better luck next time!
Aug 01, 2010, 02:37 PM
Registered User
hklagges's Avatar
Hello there,

thanks for the field & damage report. Some comments below.

You can shorten the takeoff distance enormously by switching the TV nozzles on. With them, you can (or at least I could, and I have a Su-47 with a similar AUW as you have) rotate after 10-15 meters (30-50 feet).

Regarding the tail heavyness: This plane seems to be really tricky. You had it at "1-1.5 cm behind factory setting". When I tried it at 1.5cm behind factory setting, it was tail-heavy as yours - terrible. But when I had it at the factory setting, it seemed nose heavy to me - where is the sweet spot? Maybe some pre-trim of the control surfaces (canards 3 up, elevators 1 down) would help more than moving the CoG backwards?

Regarding the touchyness on the controls: Absolutely. It is easy to overcontrol it. I am considering to remove roll from the canards and elevators and have it only on ailerons and tv nozzles.

The head-turner effect is there, but that means there is even more pressure on the pilot!

Cheers,
Henrik
Aug 01, 2010, 02:40 PM
Flying Hazard
SU-4ever's Avatar
Leet's see what happens with the Gyros, I'm really interested in your results!
Aug 01, 2010, 03:10 PM
Registered User
Mtn_Commando's Avatar
Hi Guys,

Thanks for the feedback. SU-4ever, did you mean you have used gyros on this plane? Or on some other plane? How were your results?

Henrik, since 2.5 cm is too forward, and 4 cm is too far back, I guess the logical thing to do is keep it at 3.25cm. Have you managed to work out a setting that somewhat works? I think i'm going to reduce throws by 50%, maybe increase expo from 35% to 50%


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