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Swanlander's blog
Posted by Swanlander | Jul 18, 2007 @ 03:59 PM | 3,133 Views
Flew the beast again yesterday afternoon, noticed that the yaw oscillation is rudder induced taking a few cycles to disappear. Also wind gusts caused wild roll changes.

I have looked at other biplane wing span/tail moment ratios and have come to the conclusion that the dihedral must be halved. I will attempt this at a later date when I have not impaired my senses with a couple of pints of beer!

The other issue with yesterday's flight was the loss of one ESC. It screamed as if the pinion grub screw had loosened, but worked when I launched. One minute later I had only one motor working. After landing, a sniff of the PC board confirmed that it had "let out it's smoke This was the first time I had tried a new set of Lipos on the second motor.
Posted by Swanlander | Jul 16, 2007 @ 06:52 AM | 4,244 Views
1. Vibration blurrs the video.

Solution:
Move the cg of the camera close to the line between the suspension points at the booms. Also fitted silicone tube isolators. No more problems.

Took her to Wales for the inaugural UK-AP meet, fantastic weekend!

2. Now there is no vibration, the video is almost watchable, except for the sick-making motion of the aircraft when straight and level. Looks like dutch roll of some sort. I suspect using the same dihedral as a monoplane SS (but with two wings) means it is spirally too stable.

Solution (I think!):
Increase the fin volume by extending the tail moment. After all, this is why I made the booms adustable. (I even left some extra servo cable length for this very reason!) Will try this when there is a weather window.
Posted by Swanlander | Jun 27, 2007 @ 07:00 AM | 3,276 Views
All up weight with 14oz Fuji 3500 is 44oz, which gives a wing loading of around 6oz / sq ft. Pitch stability is good, with plenty of elevator authority to flare deadstick. Slight yaw trim change under power, but nothing untoward. She climbs shallowly with the current motor, but this will be addresed shortly!

Turns are amazingly tight, and she flies very smoothly. I need to make all my control inputs very gentle, as the video shows up any small bootful of rudder.

I hand launched poorly on the third flight, having moved the camera back 2". The trim change meant a rapid pitch up, combined with an unintentional 45 degree bank at release!

I applied full right , plus down elevator and waited.........Amazingly she clawed her way back to straight and level and powered away majestically!

The low wing loading of 7 square feet of wing helped here, most other low powered models would have snap-rolled and bit the dust!

I have changed the camera mount to bring the CG of the unit close to the mount centres, also I fitted silicone tube anti-vibration mounts to secure the camera rail compliantly to the booms. Ground testing shows a marked improvement, with no noticable camera blur in video mode. More flight testing is needed now.
Posted by Swanlander | May 19, 2007 @ 04:08 AM | 3,433 Views
Now I have all the bits it is time to start!

Wings are fitted with 3mm dia carbon tube spars instead of the stock glass rods, the Trailing edge is cut off to insert the rear spar at the aileron hinge line. All fixed with heavy duty gaffer (Duct) tape as I don't trust the transparent film supplied. Holes were pre-cut to fit and bind the interplane struts to upper and lower wings.

Now I have to make a jig to support the wings in their relative positions so I can bind the struts to the spars.

19/05/07
Posted by Swanlander | Feb 03, 2007 @ 08:43 AM | 3,916 Views
Now the aircraft modification is just about as I want it, here are the stats:

Fuselage + Wing supports, 3 servos, ULTRAFLITE D/13/32 motor,
3:1 ratio turning APS 9x6 Prop,Tsunami ESC and camera mount = 450g
Flight Battery 1200 "Flightpower " 3p1s lipo = 81.4g
Wings Strengthened and fitted with 2 servos = 180.5g
Fuji E900 camera with 2x AA cells = 220.0

Total = 999.0g (35.5 oz)
Wing loading is 10.14oz/sqft

(Stock slowstick has a wingspan of 46.3" and area of 505 square inches = 3.5 sq ft)

Next SS to be a bipe



3rd February 2007