FeiJi's blog archive for September, 2012 - RC Groups
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Archive for September, 2012
Posted by FeiJi | Sep 22, 2012 @ 08:58 AM | 5,290 Views
X45WL II - Finless EPP Delta Wing (3 min 59 sec)

Previously I had built a wing (X45WL) in dollarstore foam but after a few crashes it wasn't airworthy anymore and so I promised myself I would build one again in EPP foam. Here is its successor in laminated EPP foam, finless, bigger motor with a little larger dimensions and pretty crash resistant.
Although it looks like a stepped wing in fact there is laminate over the exposed spars on the leading edge that makes for a crude airfoil without an actual step.

Material: laminated 9 mm EPP foam
Construction Time: 3 hours
WS: 700 mm
Root Chord: 540 mm
Tip Chord: 80 mm
Sweep: 580 mm
Wing area: 336 sq.in.
Weight: 350 grams
Wing load: 5.29 oz/sq.in. - WCL: 3.5
Motor: 1800kv 7*6 prop
Batt: 1100 mah lipo
Esc: 30 amp

Used this exceptionally great CG calculator and could have gotten a more exact calculation using multiple panels but I was lazy: http://wingcgcalc.bruder.com.br/en_US/

I am really happy with how well it flies (for me anyway) though it is definitely not spin proof (imagine a tail would cure that but I think the spin is funny). Guess I need to learn spin recovery next. The video shows how to land a delta wing like a helicopter.
Attached photo of approximate dimensions.
Update 9/24: Took it out for a flight this morning at 5:00am and it flies different than before, wing rocking. Nothing has changed, except the temperature which is 15 degrees Celsius colder. Looked at the wing and one is warped now. Nice theory anyway.
UKpdate 9/25: After reironing the laminate and putting some weights on it I got most of the wing warp out and it flew beautifully this morning. I can make it go into an inverted flat spin by rolling it too tightly for too long - there is no recovery though, I have tried everything and nothing seems to work - it just floats down like a leaf.
Posted by FeiJi | Sep 16, 2012 @ 01:53 AM | 4,281 Views
Got it flying pretty nicely now. Bit of a hog at 680 grams but nothing a bigger motor won't cure. No stalls but you can still dive it into the ground if you want.

Forward Swept Finless EPP Foam Wing (2 min 4 sec)

My thick finless wings are very stable while my thin finless wings want to waggle in the turns and I just let them.
Posted by FeiJi | Sep 12, 2012 @ 06:28 PM | 4,576 Views
I have been working on a forward swept EPP finless wing for a week or so and finally after the third version I got a successful flight.
FSwEPP Wing - Forward swept flying wing (2 min 5 sec)

The photos show how I constructed the first version and then I had to modify it by lengthening the nose to get the CG out where it is supposed to be.

This Wing CG Calculator, http://wingcgcalc.bruder.com.br/en_US/ helped me a lot because it allows multiple wing panels and negative sweep. I couldn't believe how far forward the CG had to be placed.

Motor: 1800kv (I think) and 8*6 prop
esc: 30amp
batt: 1100mah
AUW: 600grams
WSpan: 1 meter
material: 9mm EPP that has been laminated with copy shop laminate (very strong)

The video is unedited and taken at 5 am (haven't reset the clock in the video) - had to fly before the campus students woke up and started milling around.

Haven't flown it enough to get a feel for flight characteristics but it seems pretty stable - wind was blowing a bit and it doesn't waggle like my conventional finless wings.

Update: 9/14: flies nice in no wind, waggles in wind. Going to try dihedral.
FSwEPP Wing - Forward Swept Wing (1 min 37 sec)
...Continue Reading
Posted by FeiJi | Sep 09, 2012 @ 06:18 AM | 8,936 Views
I started flying a year ago and this foam Cessna was the first plane I bought but I never flew it. I robbed it of the electrics to build foam wings and learned to fly on them.
Finally last week I put in a new brushless motor, esc, lipo, prop, prop saver and with a new radio maidened it. Great little plane. Very easy to fly and predictable.

Can now do inverted, loops and sort of rolls. I broke the original landing gear and used bike spokes and a couple of cable clamps to kluge one together. Going to change to aluminum flat gear soon.

I love flying wings but this plane is a much more relaxing fly. And it was cheap.

Motor: emax cf2822 (the screws tend to vibrate loose)
esc: 30amp
lipo: 3s 900 and 1100 mah
prop: 8*6 with prop saver

RC LanYu Cessna TW-747-1 Flight (3 min 15 sec)

Update: 9/11 Added pictures of my new aluminum landing gear. Nice strong gear and smooth axles.
Update: 9/15 Wow landing gear is great, tough. Its the simple things. Flying rolls now and outside loops. If I had flown this plane first a year ago instead of learning on wings I would be a much better pilot with more airtime. But the struggle with wings was tough and satisfying.
Rats, flew 40 minutes today and then on last landing hit the landing gear pretty hard - landing gear is fine, but the plastic bracket it is bolted to a little bent in. Still flyable but not as pretty now. Guess that down side of the aluminum gear is that all that force has to go somewhere else now. Well,...Continue Reading
Posted by FeiJi | Sep 03, 2012 @ 10:26 PM | 4,150 Views
I added up the cost of planes, radios, materials ($500) and the total number of hours in the air (21) to arrive at a cost of about $24 per hour to learn to fly in my first year. That includes a computer radio and receivers, lipos, motors, escs, servos, sheets of epp foam, chargers, tools, etc. that I still have use of and two flyable wings.

So my second year of flying should be much less expensive. I had a RTF Cessna in which I used the gear to build foam scratchbuilts. Went through Nutball, UFO, 1B1M, Blucore Wing and my own design to get here with numerous crashes and one lost plane but am very satisfied with my progress.

I have finally gotten the Cessna together with a brushless motor and lipo and new radio and will maiden it tomorrow - taking the long way around.