Aussie Plank

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rotax618

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Joined
Oct 31, 2005
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835
Location
Evans Head Australia
I posted these photos on another thread relating to the Winton Opal, but I think it is interesting enough for a thread on its own.
The photos were captured stills from an old video “Australian Ultralights and their Pilots”, I visited the builder many years ago and inspected the machine - I’m not sure he is still alive as he was more ancient than myself at the time. The airframe is/was in a hangar at South Grafton NSW Australia.
The aircraft is probably classed as a pusher Plank rather than a “Prop in slot” even though the elevator is behind the prop. The engine was an inverted 60hp outboard marine engine using direct drive, the builder estimated 40hp in that configuration, he said that the engine was pretty unreliable which stopped him doing more flight testing.
He reported that the takeoff run was a short 150metres and a similar landing distance, the Plank displayed no vices and had no discernible stall, only a higher sink rate.
The airframe was extremely simple and used a single 100mm tube spar and ply ribs.
I don’t know who I could contact to get permission to put that part of the video on youtube.F7CA16D8-04AA-41C0-95BF-C68BD7918BBF.pngE3F45170-F4F4-4625-8871-7EF588FB2378.png5669628B-5F5F-4FD9-A2BB-35DD7AD80D34.pngC281AEAD-17DE-4F32-80DC-269113A65C3D.pngEDB5E7AB-A24A-4368-98CB-387E8B3C9E92.png583EC46F-FB2F-42BE-BC83-FF64BBB6955C.pngD43D3CFE-E98E-4E4A-8A6E-16240AFC3717.pngA7F8F5F8-FEDB-4F80-BA19-CA79009E55C2.png382B757F-A704-49AC-9387-73ECE03CFBC3.png
 

plncraze

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May 11, 2006
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1,799
Thanks for sharing! The folks who understand flying wings and build and fly them considered them safe machines. The airfoil looks like an inverted normal airfoil. Those are great pictures too. That reminds me of the Skyjacker which now tests in a storage lot. My guess is your builder controlled weight better. Between your creations and the others you find you share some neat machines here. Thanks again!
 

rotax618

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Oct 31, 2005
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835
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Evans Head Australia
There is/are no rudder/s, only endplates on the wingtips, the builder said that it didn’t need rudders the turns are perfectly coordinated, the tricycle UC would help with X-wind landings. I suppose it would fly like a “bank and yank” flying wing model.
 

Topaz

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Jul 29, 2005
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Orange County, California
Personally, I'd want a little more rudder authority on this thing. Other than that, it's an extremely simple, quick-build sort of aircraft. The only performance metric it'll destroy is "speed of build", but that's okay, too.
 
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Mike W

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Nov 3, 2012
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59
Location
Doncaster Yorkshire UK
There is/are no rudder/s, only endplates on the wingtips, the builder said that it didn’t need rudders the turns are perfectly coordinated, the tricycle UC would help with X-wind landings. I suppose it would fly like a “bank and yank” flying wing model.
My plank tends to weather cock into wind as soon as it lifts off. See test pilots report under thread "Plank progress". At present I am doubling the opening of the drag rudders and also making them open together and reduce the landing distance caused by a low drag aircraft.

You have set me thinking that weather cocking on the MW9 is caused by the large aft mounted fins and may be reduced by fitting end plates.

Otherwise the elevons give adequate control for normal flight. We need to modify the model and try it with end plates.
 
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JWP

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Apr 16, 2019
Messages
4
Rotax618, thanks for posting the pictures and info and have a fascination with wings, I have been building RC variations of this form of plank wing for decades in all kinds configurations. I have tried different wing tip types, rudder, no rudder, different airfoils, varying aspect ratios and different construction techniques.. I have come to prefer the low aspect ratio symmetrical airfoil versions. They are extremely controllable and as reported above do not stall, that is if the CG is set appropriately forward enough this is critical to have them fly properly and while it can vary a small amount its not overly forgiving. ( if it isn't set correctly stalling is going to be the least of your concerns ;) ) You can haul the elevons all the way back and it just settles into a flat nearly vertical sink and while slow its still fast enough to make you want to avoid meeting the ground that way. It just goes back to flying as soon as you release your back pressure so it makes a great way to bleed excess altitude and reduce landing roll.. My last version of this uses a tractor configuration instead of the pusher they both have their pros and cons... The low aspect ratio planks have a good speed range and excellent flight performance... If all goes well I hope to start building one full size, been on my mind for a few years but never had the time having recently retired makes it seem feasible now...nothing fancy just a simple wing.. It should be a lot more interesting than the full scale aircraft I have flown to date... The model I am currently flying is a quarter scale version of what I hope to build and I have enjoyed flying it a great deal...My avatar is a picture of it..
 

rotax618

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Oct 31, 2005
Messages
835
Location
Evans Head Australia
I would be very interested to see your model, and how you overcome the lack of visibility in the tractor configuration. I have been toying with a high Arup style wing similar to this model someone has put on youtube.
 

erkki67

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Feb 18, 2010
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Location
Romont / Fribourg / Switzerland
I would be very interested to see your model, and how you overcome the lack of visibility in the tractor configuration. I have been toying with a high Arup style wing similar to this model someone has put on youtube.
love it, and if had folding wings perfect (downward)
DAD0F429-6D58-4976-A47D-6CC74E82F9A1.jpeg 015E992E-C81F-4F23-B2A2-CFA4BA1E20B3.jpeg

An a sturdy landing gear for the big shocks.

now, for a man carrying bird, would a B/S be sufficient for power?
 
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