Here’s a video* of the Scratch-built skywalker in a couple of flight tests in Brittany R/C field over the weekend. I had to make a couple of changes in the motor thrust angle as the plane had a tendency to pitch down when the throttle is applied. It was a tad too windy for a flight test, but I was able to fly the plane in previous tests in a similar condition… I wont certainly fly in this condition if it were a maiden flight.
I recently bought the real thing, a 1.9m 2014 Skywalker. I’ll post some build images and the maiden soon.
* courtesy of the wife =)
The new wings I’ve been working on for the last couple of weeks was well worth it.
Here it is last night, with the skin on:
And finally, this morning ater a successful flight:
The 1.4kv turnigy aerodrive motor, 10×6 prop and 5000mah battery gives ample thrust.. the plane can fly really fast.
Stall speed is low.. even lower (it seems) than my 1.4m hitec skyscout. No doubt the airfoil (as close to NACA 4412 in case you’re interested) made a huge difference.
However throttling up causes the plane to pitch down negating the lift.. nothing which some up elevator cant fix though. It looks like I need to put in some more down angle to the motor now that the CG is known.
The elevator also needs to be secured more firmly to prevent it from rolling (wagging really) which affects the flight characteristics somewhat specially when banking.
Will post a video soon!
Well last saturday was THE day.. and it turned out to be a disaster. My worst fears has materialized and the construction decision to cut the CF spars did return to haunt and bite me.. here’s the vid:
Thanks to my videographer (Jas the wife).. for a great seconds from disaster video! =)
The wing connections are finally done. The 2mm (or is it 3?) carbon rods seems to be strong enough for the wings.
Ive also cut the platform for the ESC etc..total weight is 1320grams! Less the motor which weighs 111g thats 1.219kg or 319 grams heavier than my target empty weight of 800g.
The main fuselage is done!
It looks like a gigantic shoe too =)
Found a pilot lying around.. google bot.. and he looks like hes raring to go fly!
A look with the wings (which ill complete tonight):
Did some work on the plane tonight and was able to finish installing the main fuselage section with the wing base on top and added some “strengthening” PVC at the back and front.
At another angle:
Update: a few hours later..more panels..
I have 4 more days to finish this for the maiden. I reckon I can finish the fuselage tomorrow.. the wing attachments on wed, the electronics and servos on thursday and friday.
Crossing my fingers!
Today I finished some important parts of the project. The motor is screwed to a couple of pieces of high density boards which sandwiches a PVC strip(from an electrical conduit). This is installed(ie glued), at an angle, to the base of the plane like so:
The angle (the motor slightly pointing down about 5°) is done to offset the forward and down effect of a higher mounted motor. Doing this angle offset will cause the back of the main wing to have a slight down push forcing the leading edge of the wing to pitch up.
Once the motor mounting is done.. the section where the main wing is attached to the fuselage needs to be made.
The image above is upside down and shows the CF rods that’s used as the scaffolding for the wing base as well as the CF rods where the rubber-bands will be attached. I sure hope its sturdy enough!
Finally, I began making the rest of the fuselage. The space inside is big!
A deeper look at the cave..
Its beginning to look like a real Skywalker:
So far i’ve added about 50g at this point.
Finally finished wrapping the thin foam on the wings.. with all those glue I have to say they’re on the heavy side with each wing weighing approx 288g (including spars).. or a total of 576g.
This means I just exceeded my target weight for this par by at least 200g! Anyway theres nothing much we can do anymore.. just have to continue trudging on until completion.
The main wing is getting there but.. as expected things are getting a bit dicey on the weight department. The total wing weight (without the final “skin”) so far is a hefty 461g!
Here’s the work so far:
The dihedral on the wingtips requires some care to secure:
But it seems to be sturdy enough.. I know all those glue will return to haunt me in grams =(
I began working on the main wing again today and decided to cut the two 1m CF tube spars in two and just stick a bamboo barbeque stick in between, like so:
Bad idea.. this means that the load and wing twisting stress will be focused on the contact points of the bamboo spar and the CF tube which can mean disaster.
At this point i couldnt really revert to using the whole CF spar as the halves are already well glued to the wing. The only option therefore is to just join the wings together permanently and charge this to experience.. $%@$!.
Still about 75% complete.. the main wings now weigh about 320g.. it will most probably weigh about 450g eventually which means I have less than 100g to complete the fuselage. Doesnt look too good, at this rate the plane will probably weigh 1kg empty =S