There's more

[Marty_d]

That'd be a target for every trolley in the supermarket car park.

 

 

[planet47]

Looks okay to me pylon500 but may be you could do an image of the finished product in gold?

 

 

[bexrbetter]

Thanks for the updates P47, appreciated.

 

 

[pylon500]

Best I can do in a hurry...

 

Takes a while to get back into using photoshop, and I was never a pro in the first place.

 

 

 

[planet47]

 

 

 

 

[planet47]

[bexrbetter]

Well done!

 

 

[planet47]

One day soon (I suppose) I will probably have to part with my beloved quicksilver. It was never just a plane - it was also the first thing I ever owned without having to get a loan and the first time and only time I have towed a trailer by myself over a good portion of Australia to bring it back here (thousands of kms at 60-70km/hour over 5 days).

 

It feels like preparing myself to lose a limb!

 

 

[bexrbetter]

It feels like preparing myself to lose a limb!

 

 

[rotax618]

The concept looks good but I can see two problems, unless you have something very heavy to put in the nose or you are planning on sweeping the wings, I suspect that the pilot and pass are not going to bring the CG forward enough for stability. The second problem is getting smooth air to flow around the rear of the pylon into the prop.

 

I have had some experience with this problem when I designed and developed the Boorabee, which is a tandem and therefore less of a problem, I finally solved the problem with vortex generators.

 

Vortex generators can delay the separation of the boundary layer by re-energising it, wings equipped with VGs still stall but at a greater Angle of attack, typically 15-18deg, from the looks of your design the rear of your fuselage is 30-45deg taper. You will probably be better off tapering the pylon 15deg and chopping it off square before the prop ( Kamm tail)

 

Please accept my criticism as an attempt to help. There a far too few people willing and brave enough to design and build their own creation.

 

 

[pylon500]

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.

 

 

[rotax618]

Pushers are always noiser than tractor aircraft, particularly for the persons in front of the prop, pilot-passengers. I think that the noise of the engine and particularly the exhaust is being reflected from the propellor disk forward. I was going to test this by extending the exhaust outlet down and along the boom to exit behind the prop. Unfortunately all of the pushers I built had 2 stroke engines which dont perform well if you modify the exhaust.

 

Another problem I encountered was a pulsing and vibration when I used a 2 bladed prop, this was caused by the prop blades passing through the wing wake in unison, three blades fixed this although 2 blades gave a better cruise.

 

 

[planet47]

This girl has got thus far

 

 

 

[planet47]

It used to look like a boat now it looks like a ship wreck

 

 

[planet47]

The shipwreck has become a boat again yay

 

 

[planet47]

I'm told the other day that soon I will have to look at wing strut material - any suggestions?

 

 

[planet47]

Whoops - I asked a question

 

 

[rotax618]

Lightwing (Hughes Aviation at Ballina) still have strut material, the same as used on their Lightwing, not sure that they have the smaller size but I bought some of the larger section last year. The larger section has about a 32mm internal minor axis.

 

 

[facthunter]

Yes streamline section aluminium, either extruded or formed from sheet folded and riveted at the trailing edge. Could be around a tube. Nev

 

 

[Marty_d]

Yes streamline section aluminium, either extruded or formed from sheet folded and riveted at the trailing edge. Could be around a tube. Nev

Nev, I've been considering streamlining the 701 struts (when I make them). Plan calls for round chrome moly which I've already bought, and I generally try to stick to the plan, but I also know there's a hell of a lot less drag if streamlined.

 

If I do fold a sleeve and rivet at the TE, what's the best method to fix to the tube? Does it only require a couple of rivets top and bottom, or should there be a full length row - if so, does that weaken the strut at all?

 

 

[rotax618]

Rivets do weaken the tube, the best solution is to only rivet the fairing at the ends of the strut and use a high strength double sided tape where the fairing touches the strut tube top and bottom.

 

 

[facthunter]

Having a rivet line at the Trailing edge is not much of a reduction in the section and the number doesn't affect the principle as it does in a stressed lap joint where the total number is significant in reducing cross sectional area. If you have a chrome molly tube why not use something like balsa or foam with a coating held on by straps. It's not load carrying, just streamlining. Nev

 

 

[Marty_d]

Having a rivet line at the Trailing edge is not much of a reduction in the section and the number doesn't affect the principle as it does in a stressed lap joint where the total number is significant in reducing cross sectional area. If you have a chrome molly tube why not use something like balsa or foam with a coating held on by straps. It's not load carrying, just streamlining. Nev

I thought of lapping the fairing at the TE so the body of the rivets are inside the fairing - like this:

 

 

Surely that would be a substantial drag reduction?

 

 

[facthunter]

It will be a substantial drag reduction with a section like that. More so if the rest of the plane has a bit of a clean up, and you are cruising above say 60 knots. Don't put rivets into your main structural tube as it will weaken it and create failure points. Nev

 

 

[Bruce Tuncks]

I agree. A round section is terrible for drag. I have been told that a 1/4 inch diameter rod has the same drag as a Libelle wing.

 

If you make the section too blunt, the airflow will separate before the trailing edge. I used to see this on my early SK Jab with the round trailing-edge struts. You could see the separation point when a little light rain left a line of dust, and those struts left a separation wake of about 15mm.