Not CL but cool, RC Sail Plane reaches 505 MPH!!

[Doug Moon]

Sail planes own the RC speed records.  Dynamic Soaring is awesome! 

[Gerald Arana]

That's incredible! I'm wondering how the wings stay together at those G loads......

And what it weighs.

Jerry

[Randy Cuberly]

That's incredible! I'm wondering how the wings stay together at those G loads......

And what it weighs.

Jerry

Chip hyde spent a few days here in Tucson last year getting some coaching on the stunt pattern from Bob Whitely and others and He told us about flying one of these monsters.
They are big and heavy and he said they absolutely Howl as the come around overhead.
The speed increases witheach lap around the oval flight pattern as the wind whips the things up to incredible speeds.  He mentioned speeds in the high 400 mph class!

Personally I was flabergasted, and a little disbelieving until I considered the physics involved.  Some quick math shows that speeds could approach the speed of sound under the right conditions.

Randy Cuberly

[tom brightbill]

This method of flying was discovered by Joe Wurtz, a multi-time national and world soaring champion.  I watched Joe DS with a hand launch glider off the end of an airplane hanger, much to the dismay of the one fellow that was standing in the middle with him.   

[tom brightbill]

My bad, I hit Z instead of S.  Joe's last name is Wurts.  (I better get some new fingers.)

[Russell Shaffer]

Is this the same principle that causes "wind up" in CL?   I asked Paul Walker why our planes wind up in the wind and he told me that the wind adds energy.  I probably wouldn't have understood a more detailed explanation. 

[tom brightbill]

Russell, it's similar except the rotation (flight path) when DS flying is perpindicular to the direction of the wind. Probably not a good idea with a Box Car Chief 😳!

[Jim Roselle]

I had a hard time wrapping my mind around dynamic soaring until I read this, complete with cool graphics.

http://en.m.wikipedia.org/wiki/Dynamic_soaring

Jim

[Dan McEntee]

  I don't think there is a catagory for this type as far as AMA and FAI records go, is there? For an FAI speed record, a specific speed course is laid out perpendicular to the prevailing wind, and the model needs to make a pass in each direction. The Dassle (sp?)is the last sailplane that I did any reading about that had the speed record for a model airplane and at that time it was in the 450 MPH range, I think. A record speed run can't be "wind aided" and the wind is what makes this type of flight possible, and they just shoot it with a radar gun I believe.
   Type at you later.
   Dan McEntee

[Shawn Lenci]

Tom (Brightbill) and Jerry (Arana).....Not to be confused with the cartoon cat and mouse by the same names.  Maybe we should take a Windsong out and try that?  I am sure we can get it up to 40mph or so before flutter would be induced.

Shawn

[Gerald Arana]

Hi Shawn,

I've got some 6 oz. cloth (glass) that we can slap on the wing and stab. That ought to stiffen'em up a tad and add some (very needed) weight too! Should be able to get up to .....oh say 50-60 mph or so!

Jerry

[Mike Scholtes]

As a slope soarer like Jerry, this is really intriguing stuff! My models are compact, strong and very aerobatic, but max out around 60 mph I would estimate. I watched the graphic Jim R posted and I think I get the theory. So, does this mean that the model adds that increment of speed on each lap? If so, it seems in theory there should be no upper limit except maybe the speed of sound where control becomes a major issue. The graphic is really good, I recommend it. I had no idea models let alone gliders could hit such speeds. It appears the lack of an onboard propulsion system is irrelevant in this case.

[John Park]

Learning to fly sailplanes in 1964, I read Philip Wills's 'On Being A Bird' in which he referred to dynamic soaring as "...the one field of soaring in which the birds still outclass us, and alas, I can see little prospect of the human bird ever being able to compete", and I had no trouble agreeing with him.  Yet a manned glider was doing it little more than twenty years after Wills wrote those words in 1953, and now we even have RC gliders doing incredible things like this.  Makes me wonder what impossible things we're going to do next!

[Motorman]

I don't get it, the wind's not going 505mph how does the plane go that fast?

[Randy Cuberly]

I don't get it, the wind's not going 505mph how does the plane go that fast?

The plane picks an added increment of speed from the energy as it crosses the boundry layer.  It maintains most of that speed as it drops into the basically stagnant air layer below the boundry and then continues around and up into the wind again where it picks up the same amount of energy as before.  Then back down into the stagnant layer where it only loses a small portion of what it gained...this cycle continues ad neauseum until something interupts the cycle like a wind change or a folded wing etc.

There are physical limits by induced drag as speed increases and most definitely physical limits to how much energy the airframe can absorb before failure.  The pressure bubble at the speed of sound might be a physical limit depending on how much energy is in the prevailing wind, etc.

It's also likely that the pilot is an important factor in reading the boundry layer to get the maximum boost as speed increases.

It's probably very difficult to fly a glider doing 400 or 500 + MPH!!!!

Randy Cuberly

[phil c]

Wind up is a form of what the gliders are doing.  So is wind flying a CL plane.  If the wind is over 11-15mph or so quite a few flyers are able to keep a plane flying by whipping and doing lazy eights- whip low into the wind, do an inside, then go low inverted and whip into the wind and do an outside.  I haven't seen it but I've heard of guys doing all or most of the pattern with a dead or no engine.

In the 60's thin winged got popular to go fast.  It wasn't uncommon to see one  blow up after a few tight loops in a 15 mph or more.  I tried it a few weeks ago with a Nelson powered ship in 15-20 mph breezes.  It did't blow up but the motor unloaded at least 3,000 rpm(sounded like an F2D) and the line pull doubled to the point there was hardy any bow in the lines, so I quit.

Flying that glider was very hard, amazing in fact.  The pilot actually lost it for a few seconds.  Fortunately they kept it out of the ground.  They never would have found all the pieces.

Phil C