Crunchie Planks - Page 12 - RC Groups
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May 13, 2012, 02:14 AM
608 km/h!
josh18's Avatar
Hey Andrew, did you ever try it after a big dive with some height left? I reckonthat would look pretty cool!
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May 13, 2012, 05:42 AM
Wind, hill, ... I'm keen ...
AvB's Avatar
I don't remember Josh! I think I just tried it on the Shorncliffe slope. But I remember some of the older more experienced guys viewed it with great suspicion ... I think they thought it was a dumb idea and that I should learn to do a proper "slide up the slope and turn into wind and plop it in" landing. But it really worked well. Better than stuffing it up and cartwheeling into the fence or on the road. It just completely stopped right where it was and fell down.
May 13, 2012, 05:17 PM
608 km/h!
josh18's Avatar
Makes me think of setting a Ninja Star on a switch for DS, as my rates always seem too low for it. You wouldnt want to hit it during the lap though!
May 13, 2012, 07:39 PM
Planes dress doors...
Rhys Porter's Avatar
Ah Josh - I think that's called a self destruct button if you hit it during a lap lol
May 13, 2012, 07:43 PM
608 km/h!
josh18's Avatar
Haha, I can do that on my own! Too often...
May 16, 2012, 01:01 AM
Registered User
Gordysoar's Avatar

Using brakes instead of guessing about them

As most you may know I have flown rc sailplanes in more places with more guys than anyone else on Earth....

Its one of things that seperates my comments from the rest...I try stuff where most talk about what might be.

Take a look at the Zupair Z1 plank. There are NO FLAPS on it. as I mentioned in my first post here on the has landing brakes that look like flaps. They pop; down 90 degrees and cause little or no pitch change.

90 Degree flaps are not camber, they are simply big flat devices that cause a lot of drag.

The wings you guys are flying are not thermal why does the topic of camber, or crow come up in the discussions?

Yes you can put mulitple surfaces on any slope wing....they'd have the same benefit as an 8 track tape player.

Slope planes are for going fast and zooming around looking cool. Brakes allow you to avoid scarfing up the skins or causing chaos on the slope trying to do some cool crabbing manuever to burn off speed and lift in order to plop down.

But if you could cause the model to come to a near slop yet have full could simply pick it out of the air.

Check out the Zupair's video showing the 'flaps' in flight action.
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May 16, 2012, 01:40 AM
608 km/h!
josh18's Avatar
Hey gordy, wth the zupair being a sweps high aspect wing, if the flaps or brakes are at the inner part of the wing then they would be acting very close, possibly even foreward of the cg due to the wing sweep. This, to me is the reason they have little effect on pitch. Try this on a propper plank and see what happens. Considering a well tuned pw51 plank can need only a couple of mm elevator travel, even if the brakes snapped to 90 degrees "instantly", you would be in the ground or at least out of control before you could blink. Feel free to prove me wrong if you have a video of it but I cant see it at all possible to brake a plank using only down flaps. Maybe some form of spoilers near the cg would do a similar job to what you discribe.
Cheers, Josh
BTW, it looks like a great plane!
Last edited by josh18; May 16, 2012 at 01:50 AM.
May 16, 2012, 01:55 AM
vespa's Avatar
Zupair is not a "plank". The substantial sweep greatly increases pitch damping and the location of the flaps greatly lessens their pitch effects.
90 degree flaps are absolutely camber. Not only by definition but in practice. I use 90 deg on most of my (tailed) planes and the pitch effects are enormous -- increasing nearly linearly throughout the entire flap deflection range.

What I have found useful for some planks is to setup a switch to put both ailerons nearly all the way up. Surprisingly I have never been able to loop like this, no matter how I try. The stall is so immediate that they simply go right into a slow, stable, bobbling "hyper-stall" descent from any speed or attitude, even inverted. Unfortunately, roll control is limited, pitch control is non-existent, and the descent is very steep so it's not be suitable for all planes.
May 16, 2012, 02:09 AM
Planes dress doors...
Rhys Porter's Avatar
That was the same wing I was talking about earlier - Now I see it's very different to a Windburner at Cactus!

Z1 With Flaps (0 min 40 sec)
May 16, 2012, 02:39 AM
Entropy is happening!
Jim.Thompson's Avatar

Swept wing - not a plank!

I'm with Josh here Gordy! Your very nice model is no plank, that's for sure.

Very impressive though!

May 16, 2012, 03:55 AM
Deniable plausibility
Shedofdread's Avatar
If you want proof that a 90deg flap IS camber, look a the 'Gurney' flaps on the TE of racing car wings and the reason we put them there.

Years ago, I had a plank based on the Kowalski (?) Phonix - that had a 'letterbox' airbrake in the middle of the centre panel. Worked OK.

I'd love to see someone try this
Scan Eagle Landing (0 min 38 sec)
with a model. But failing that, the net has the 'spectacular' effect
May 16, 2012, 04:23 AM
Auzzie built planks
timbuck's Avatar
This is how I land my brakes..

This is a back side cactus ridge a few days ago..

Composite Plank Hand Catch... (0 min 35 sec)
Latest blog entry: More colours
May 16, 2012, 04:55 AM
Planes dress doors...
Rhys Porter's Avatar
Haha Tim that's crazy... To stand in the face of a warhead 60 and catching the damn thing is truly nuts...
May 16, 2012, 05:04 AM
Auzzie built planks
timbuck's Avatar
Originally Posted by Rhys Porter
Haha Tim that's crazy... To stand in the face of a warhead 60 and catching the damn thing is truly nuts...
WARBURNER 48... 1.1kg..
Windburner wing with warhead fuse.
Latest blog entry: More colours
May 16, 2012, 05:20 AM
closed due to popular demand
Last edited by ibuild; Oct 19, 2013 at 03:30 PM.

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