Build Log Slipso400: Club/sports 400 pylon racer with plans

[pldaniels]

Originally Posted by Stuntman

Yeah I like to use triangular stock and would probably go to a soft light 1/4 sheet. Then you can really get into it with the plane (something about plane shavings, be it balsa,

I know what you mean about shaving away being theraputic (except when I'm shaving my face). 1/4" side sheets I preume you're meaning? You could probably get away with pushing the whole fus sides inwards except for the nose, would be a tight fit, depending on what you do with the ailerons (I'm using torque rods with the heat-shrink join menthod). As for glassing, I was going to use 25g/m.sq across the entire fus. Last time when I partially glassed the fus it cracked on a bad landing where I didn't glass.

Paul.

[pldaniels]

well well - no one in the "big city" had any cells of any reputable form, sometimes this place is terrible.

Anyhow, it's nearly midday here on Saturday and I need to finish up the slipso by tommorow afternoon, should be do-able.

Paul.

[shhhhh!]

Paul,could you describe how to do the brown paper and white glue technique? Thanks,Dave

[pldaniels]

Dave,

It's not too hard (Really!)

What you need -

1. Brown paper (supermarket, book covering brown paper)
2. PVA/Whiteglue/Elmers
3. Creditcard/squeegee

Cut out your brown paper to approximately the size you want to cover, much like with ironon films. There is usually a shiney and a rough side of brown paper, you apply the glue to the rough side.

Mix up your PVA with water, the exact consistency is dependent on your brands, for the stuff I get here I use 1:1 PVA:water mix, for thicker glues like Weldbond you may need more water. The consistency you want is similar to slightly thick milk and it should be easially brushable like paint. The key is that you need enough PVA that there will be enough for the bond but thin enough to make it brushable - experimentation is the key.

Brush on a light layer of pva/water onto the balsa, this sets up and seals the wood a bit.

lay your brown paper rough side up and brush on the PVA/water mix, make sure you go all over the paper else you'll get some strange wrinkling effects

When the brown paper has been wetted, lay it over your balsa, you'll find that you will need to fairly accurately place it as it tends not to want to move around much once you've put it down.

Now, working from the center of the wing, with your creditcard start smoothing out the wrinkles, you'll find there will be some amount of PVA/water that comes out the ends.

There may be some wrinkles in your work, don't panic too much as we can sand this out later.

By now you'll probably find your wing is starting to 'warp' a bit from the water, this is where you need to make sure it's weighed down with some non-sticking metal or plastic items. Be aware that where ever you pin the wing down it will tend not to dry (lack of air exposure) so make sure you use relatively small contact areas ( I used right-angle aluminium ).

Once the wing has dried you can either leave it as is (and cover with laminating film or something else) or you can sand back the wrinkles which will roughen up the entire surface and apply more layers of PVA/water mix.

If you can get a perfect setup initially then you can just immediately paint or cover with film, the choice is up to you.

Hope that has helped a little bit - perhaps next time I do it I'll do a small video.

Paul.,

[pldaniels]

Okay, just sat down after putting the 2nd coat of WBPU onto the fus (glassed with 25g/m.sq)

Here's a couple of photos.

Shaped fuselage waiting to be covered


Fuselage mounted onto its 'stand', this allows me to move the fuselage around without having to touch it directly.


Waiting for the first coat of WBPU to dry. I initially painted the fuselage with one coat, applied the glass when it was still sticky (it pays to wait 10 mins rather than trying to put it on immediately)

[pldaniels]

FINALLY, at long last I'm done...(well, it can now go for a maiden flight)





Paul.

[pldaniels]

Well, the Slipso400 (#2) has survived, isn't that all you needed to hear?

Speed has definately improved (I suspect because the wing is a lot slicker than the CA/glass) but the model isn't as responsive (because it's more nose-heavy this time) however that's not a big issue as I'm still getting used to the pace.

The slipso holds a 30~45 degree climb but won't pull might further than that without slowing up.

Landing is a bit hotter though fortunately with the experiences from last time it's not so fear-inducing, I just chop the throttle as it passes me going down-wind, travel another 30~40m, turn around, wash off speed and height, line it up and slowly feed in some elevator and it _usually_ landed near enough to me.

All up I'm very happy with this build, it's progress from the previous one.

AUW is 373g with a 128g 8 cell 5/4AAA 830mA NiMH pack.

Paul.

[pldaniels]

Oh, one rather important comment --- heating is a big issue. I really need to work out some ventilation before I toast the magnets on this sp400 can.

Paul.

[Arbo]

Congrats. That wing looks a bit more slippery.

I'd try a little scoop up by the nose and an exit hole, perhaps behind the TE of the wing... that should get some airflow in there.

[pldaniels]

Arbo,

I ground out the underside of the removable rear half of the top canopy, so there's a nice exit vent there (especially onto the low-pressure side of the wing) but I will still have to add an entrance hole up by the nose as you suggest.

Another idea I saw with the F5B's was to actually put holes in the wings over the fus section - was an interesting idea.

I've left the flux band on the sp400 - should I rather take that off?

Paul.

[Stuntman]

Yeah, rip that flux ring off - that should give you a little more rpm.

I was going to suggest a hole in the wing. Youve got to get that air out

Looks really nice and classic with natural finished balsa and paper with black trim.

Shawn

[pldaniels]

Shawn,

Just got back from my 2nd flight. I added a cooling scoop in the nose to get some air in, also to let me test the temperature of the motor (with my finger ).

Flight seemed a little longer (WOT the whole way) and managed to cram in 10 laps of an imaginary circuit (but I have to start learning to turn LEFT, not right).

When the plane came down the motor was fractionally hot to touch. That is it was on the 'bareable limits' of human skin, though personally I'd rather not leave my finger on there longer than 2 or 3 seconds.

On the bad side of things, the black/brown wing seems to be impossible to see clearly at some angles when the sun makes it all "black" - only way I rode out of it was to "trust" (hope) that I was looking at the top-side of the plane assuming that nothing bizzare had happened at the last turn

And now here's a pic with the scoop...

[pldaniels]

Too low, too slow, down-wind... CRUNCH.

Classic tipstall situation. I was finishing up a nice 4 minute run, ESC cut out, I was at the far end heading downwind and low on altitude. I _should_ have just lined it up and landed it immediately without turning.... instead I tried to bring it down to my location and turn it into the wind. It was about 1.5m off the ground, slowing right up, I knew what was about to happen, tried to throttle up but it was too late, all I did was send it to the ground (throttle can be reactivated after it has been reset to zero for a few seconds).

The entire front area up to F2 has folded up like some neat origami. Wing is perfectly fine, everything beyond F2 is perfectly fine. Motor has a bent shaft - I'm really going to have to learn how to straighten these, can't afford to keep buying new ones.

Paul.

[SargeNZ]

Paul, I have been holding out but I really must have input now

Now that's TWO speed 400 racers you have boogered, Whereas my Sorta-sokol on the other hand is still going strong .........I'm just trolling.

I really suggest you bite the bullet and get some nice Kan nimh or something similar unless you already have, that and get used to landing fast.

Another thing, cold morning + finger thro cooling hole + cooking motor = burned finger.

Good luck. Sarge.

[csisfun]

Hi Paul,

Nice plans, makes me wanna build one! Just wondering; where is the peak of the airfoil indicated on the wing plans?