Monday, February 18, 2008

Chuck Glider discus launches Gambler AG

This is not a free flight glider. I've been dabbling with the "dark side" and my chosen weapon is the Gambler AG from Wright Brothers RC.

Why am I dabbling in the dark side (aka radio control)? Well, there is method in Chuck Glider's madness. The main reason for playing with RC is to learn about discus launching - what it feels like and how bad launches go!

The latest thing in free flight chuck gliders is the discus method of launching, also called tip launching. This is a field of aeromodelling where free flighters have learned from our radio control cousins (not the other way round, as is usually the case ;) ).

The Gambler is a fine model and I've thoroughly enjoyed flinging it about to play with low level thermals. Best flight so far is nearly 3 minutes
(in wintery conditions). I have not flown it in good thermic conditions yet and am looking forward to that!

The next stage would be to build a free flight DLG! So watch this space....

Thursday, February 14, 2008

Polish Aircraft - Superb Scale Subjects

I've been a fan of Polish planes ever since I watched a full-size Ogar (SZD-45) taking off at an airfield. This is a motor glider designed in the 1970s and is simply hypnotic to watch. No wonder they issued a stamp picturing it (left).

After I had the fortune to fly in other Polish gliders, such as the SZD Junior and Puchacz, I was hooked. They were well made and handled superbly. The SZD-55 is to my mind one of the most beautiful gliders ever.


Now here is a fabulous Polish movie, probably from the early to mid 1960s. It seems to be about wave soaring in the mountains. You need to put the sound on, because the music (Moon River) adds to the effect. Watch out for the footage of an SZD-22 Mucha Standard glider, a model sailplane (at 3:50 minutes in), the Mucha Std being aerotowed by a Gawron (4:40 to 6:30) and the super streamlined SZD-24 Foka glider (8:25).



The Polish aviation industry has a track record of coming up with amazing, ground-breaking and eye-catching designs. PZL means "state aviation works" and no doubt, early on the industry was heavily state funded. After SOLIDARITY and the rise of capitalism, it seems that some of the aviation industry was bought by the European aviation giant EADS. I have never fully understood how the industry is structured and organised. Currently, there seem to be at least two glider manufacturers - PZL Swidnik (who make the PW5 and PW6) and SZD Allstar PZL Sp. z.o.o. (who have a long history in sailplane manufacture).

In the early 1930s, arguably the best fighter plane in the world was the PZL P.11 (photo right). It had these amazing parasol, gull wings. It is not difficult to see why it is a subject for scale modellers, though perhaps not common enough. At that time, the pace of aeroplane development especially in Germany, was very fast and the performance of the P.11 was soon surpassed.



The PZL 101 Gawron was designed in the late 1950s/early 1960s for agricultural and other civilian uses. (Photo left; the tug plane in the video above is one of these). I have not seen a free flight model of it, but it would make a fine subject with those wing tip plates and slightly swept back wings.



The PZL 104 Wilga (left and below) is a fairly common subject for RC models - both scale and semi-scale. With its slightly quirky but cute looks and short take off run, it would make a great rubber or electric free flight model. It makes a good glider tug, full-size and I suppose, as a model.






The PZL 130 Orlik (below) is a very small, ~10m span, 2 seater, highly versatile training plane. It is used by many air forces and the Polish Air Force display team.



The wing planform and the proportions are fabulous (see the three-view below). This would make a lovely model plane.












Unsurprisingly, Poland has produced some fine pilots and aeromodellers too.

Saturday, February 2, 2008

Chuck Glider from one 1/16" balsa sheet: Part 5, FREE PLAN!

The final plan for PLAIN SAILOR is below. Right click to save it.

Flying the prototype revealed a weak point at the fin to fuselage joint. This is because the main strength at that point comes from one side of the fuselage, that is, 5mm of 1/16" balsa!

So, I cut the fuselage at the stab and trimmed the fin down, as it was too big. After re-attaching the tail feathers, the glider was much better behaved. I guess the moment arm of the prototype was too long. Compared to the prototype, the overall length (not including ballast) of Plain Sailor is 18".

Unfortunately, I do not have an indoor venue to fly in, but outdoors in the calm evening air I was getting flights of 25 to 30s. I'm sure that could be improved on with more work on the launch and transition trimming. However, this model was not designed purely for duration, but also for the other "tasks" that make up the one-sheet indoor competition, including longest glide and spot landings.

I used a small pea of blu tack on the left wing and a teeny bit of left rudder to get it flying conventional right - left. Take those trims off and it will go straight and level, since there is no stab tilt.

To make it suitable for outdoor, I would suggest gluing a thread on the LE with CA, increasing the dihedral to 2" under each tip and finishing it with 2 coats of sanding sealer with very fine sandpaper in between them. With its light wing loading it could easily fly away in thermal lift. Higher launches would require a decalage setting closer to 0-0, but as has been discussed before, that can introduce inconsistency in way the glider recovers at the top of the launch.


If you build this simple glider, please let me know how you get on.
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