pylon500

Just guessing at the power output (or lack of it) from the Skylark, and low speed airflow, I would be guessing at something in the 34x18 to 36x22 size range. If you don't actually plan to fly the engine/prop, it doesn't have to be perfect. Calculating, marking and carving a prop isn't as hard as many think, the real 'art' is how to lay out the twist and the planform. Really basic propellors like the Scout prop, the Allsize props on the Skyfoxes or many of the WW1 vintage props, use the same concept and simplicity. (I can hear the Allsize lovers getting angry..) Start with a block of wood, laminated if you want, or just a medium weight hardwood (I wouldn't use common Pine, but a nice straight grained piece of Cypress Pine would be OK), I've used darker coloured Maple or Meranti in single block for short use props. The pitch calculations are not as hard as you might think.. Say an 18" pitch, on a 34" diameter prop. A 34" diameter is (Ø x π) which is 34 x 3.14= 106.75" in circumference. An 18" pitch means we want a triangle 106.75" along the base, and 18" high at one end. Using simple trigonometry (or a calculator) you find the angle at the low end of the triangle, 9.57° Lets assume a piece of wood, 34" long, 2½" thick and 4" wide. Draw a rectangle that represents the end of your piece of wood, 2½" by 4". Using a protractor, draw the line that represents the pitch angle from one bottom corner. Take your 34" long prop blank, figure out which way the motor turns (!), and determine the trailing edge at each end of the block. Mark the height as shown by the arrow, on the LEADING edge of the block. (This layout will give you a SQUARE prop!, if you want it tapered, there's a bit more work...) Repeat all the above calculations and markings for each inch inwards along the blank, remember, one inch in on one blade, is TWO inch less for each diameter calculation. You should end up with; All these lines are the UNDERSIDE of the blade section at each point. When the angle goes out the top corner, stop the marking. If that point is more than say 6" from the centre, you may need a thicker piece of wood. From here on, check various youtubes on how to carve (I've got to go to work..)

If you are planning to run direct drive, the old Scout prop would be way too big. I was playing with a couple of Kirby (Tecumseh) 144cc motors back in the beginning, running direct drive props. My last set were 32x16, and could have been maybe a little bigger? Yes, it's a pusher, I was using two of them on a home made trike.

Good point! When do we get w_i_d_e s_c_r_e_e_n avatars?

I use this gif over on Homebuilt airplanes.com, but it would also lose out if stuck in a round hole. (I'm actually amazed I still had this in my computer somewhere!

All the efficiency they gain from the higher aspect ratio wing (which is all it is), will be lost in the biplane interference caused at the strut junction, to say nothing of the section buildup created by the straight strut. NASA, well, I think mainly their students, are coming up with a lot of ideas lately, that don't really make a lot of sense, or miss obvious (counter) explanations that have been known for years. There was a lot of work (and money) spent on trying to prove some nineteenth century bird watchers theories about winglets and like, which I found on youtube; They were trying to prove that a flying wing can be efficient, but really, all it proved was that higher aspect ratio wings are more efficient aerodynamically. Don't get me wrong, I like flying wings, but the compromises involved in getting them as efficient as a 'normal layout', mean dealing with some pretty serious stability problems. It might be OK today what with autonomous artificial stability and stuff, but get it wrong in an airliner, and it'll suddenly turn into a cloud of composite bits and bodies hurtling through the sky....

Sorry Ian, don't like it. No need to follow modern trends (they will come back anyway), it's aimed at facebook and related rubbish to show mugshots, half of us have our planes instead. Planes fit in square holes......

With that much wind, he should have landed on an in to wind taxiway, or the grass somewhere?!

I thought 'Flaps 1' was more a climb-out position, with at least one stage of trailing edge (if not two?) flap for heavy take off and initial climb (below 1000')?

Welcome to GA....

Anybody been looking/thinking about the Kempsey 'Airshow' 1st/2nd October? Was planning on wandering up from Taree, so had a look at the webpage for arrival/departure and program closure times; Attractions - Wings over Macleay Then started looking into entry prices; Tickets - Wings over Macleay And had second thoughts. After a lot of digging I found the arrival/departure times; Getting There - Wings over Macleay So looks like I'm just going to have a normal day flying around Taree.

Doesn't look like a lot of flap, I thought they only had a limited number of positions? Either way, he probably should have had the next one? Was lucky he had the room to set down and get a bit more speed. Also, if the camera was in the same spot, he was taking off opposite the Airbus that landed first?

Crash a plane....?

Doesn't really take much force to collapse a strut, and have the wing fall on the ground.

Any way you can ring these guys to discuss postage/pickup? Trying to track these guys down is all but impossible, I know they're in Moruya somewhere, but that's it.

Yeah, the irony. You can buy a finished almost ready to fly model, cheaper than you can buy the balsa to make it! Although HobbyKing isn't always as cheap as you think, I just wanted 2 roll of solarfilm, and they had a good price ~$12 a roll, but with postage it was going to cost over $44 in total!! Almost cheaper to order another model, and get the solarfilm squeezed into the model box?! I thought only Hong Kong ripped you off with postage?

I was thinking Jabiru maybe?

I guess the 'gull wing' gives you that bit of being different, but a structure still needs to be 'arranged' correctly. To that end, the inner lightening holes are in the wrong place. Usually they would run along the centreline of the beam, as that is the neutral point along the shear plane. Technically, as sheet structures will resist tensile loads better than compressive loads, the lightening holes would more correctly taper down towards the lower cap, keeping more material in the compressive area of the shear web. Just saying...

You need to be careful with some of these 'scaled warbirds'. As a sideline, I looked into what people wanted, SPITFIRE ! was the usual answer, so Sullivan supplied. Almost immediately they cried, 'Can you make it a two seater?!' Idiots, I thought to myself, surprised they didn't want tricycle undercarriage!but that's the way it went; Two seat Sullivan Spitfires, Two seat Titan Mustangs, Two seat Flying Legends Hurricane, and so on. I got to thinking, if they want two seat warbirds, build warbird trainers! I started tossing up between the Chipmunk, and the Ryan STM. Then the company at Bankstown I worked for, got to restore a Ryan! (Here's where my first sentence comes in....) I quickly found out that I, at only six foot, could not fit in the front seat of the Ryan, and could barely fit in the back!! I think a good scale Ryan STM would be about 110%! I then started looking at the AT-6 Harvard, as we worked on them as well, and it actually scaled nicely. Initially drawn to have a 912 up front, the Rotec fitted as well... Not long after I started some drawings, the Flying Legends Tucano appeared on the scene. Inspired by Bryan Gabriel, I looked into a small single seat scaled PC-9, with a 582 up front. Since them I've had a few people interested in the PC-9, but a bit bigger, as a two seater. The scribbles continue...

If you want a Spitfire, and are willing to go the composite route, you should do some serious digging around, and see if you can find the 3/4 scale Mk9 moulds that Scott Winton made for George Markey. They must be out there somewhere?

Interesting! Initially thought it was the English 'Leopard Jet', with American rego to throw us, but looked up Leopard, and it's different..

As mentioned, the 6000 series is more workable than the 2000 series, even at T6 temper. If you look closely at a Spitfire, it's not unusual to see the odd wrinkle and buckle, they were built quick. The usual trick for 'compound' shapes is to do 'steps' between bulkheads, if you sight along the skins, this becomes apparent. Have a look at a Sullivan Spitfire for some ideas, he solved most of them. In stressed areas like the wing skins, using the multiple skin join steps, requires a bit of thought about number of rivets at the joins. A lot of it depends on how complex you're willing to get...

Thought it was a Klemm of some version, but I think Bucker could be right.

At least this owner could get his money back, the hard way...

Looks like a 'Mielic(?) Czech cropduster.

All these things have been worked on, no promise that I've solved all of them yet, but basically as you've said. Aircraft originally designed around a 912s, but there is an EA81 Subaru sitting there at the moment, so the wings may yet get swept. I am looking at an extension shaft for the Subi reduction system, ie, an extension between the block and the reduction system. Am toying with the idea of tall skinny radiator as the trailing edge of the pylon. Will never be able to get rid of the 'pusher' sound, but working on it.