Let's discuss all general aspects of R/C CROSS COUNTRY SOARING here.


The main website for the XC SOARING COMMUNITY is www.xcsoaring.com


R/C CROSS COUNTRY SOARING combines RC THERMAL DURATION FLYING with FULL SCALE RC CROSS COUNTRY FLYING and mixes it all up with a team on the ground in a chase vehicle. For a good overall description of a contest and the duties of the team members, I wrote an article for RCSOARINGDIGEST.COM covering the 2006 contest starting on page 32 here-

http://www.rcsoaringdigest.com/pdfs/...SD-2006-08.pdf


Many of us hope this thread will increase interest and answer the many questions people have about XC Soaring and the gear needed to participate.



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Dean

Why has the RnR SBXC dominated cross country RC soaring for so long?

I see some planes around that have about the same span but it seams that RnR has the secret formula or something.

Originally Posted by dr_sprocket

Why has the RnR SBXC dominated cross country RC soaring for so long? I see some planes around that have about the same span but it seams that RnR has the secret formula or something.

In one word, availability. RnR has made hollow molded planes for around 20 years. I think the SBXC is their most enduring design because XC doesn't go through the continual reinvention that TD/F3J ships seem to experience. Having molds for all the parts makes the production of kits commercially possible, hence the availability of a well-developed, successful design.

The other successful ships flown over the last 20 or so years that XC has been popular were mostly one-off creations of their pilots, built to the task. Usually the designer/builder made a fuse mold. That was generally all that you would start with to build an XC ship, everything else was up to the builder.

There are some big European planes that seem like they would be good for XC, but there is more than size that has to be taken into account for a good XC ship. Visibility at altitude is a key factor, along with being able to land almost anywhere without damage, and the ability to save a flight by taking a low small thermal. When these are factored in, many planes that at first look usable aren't a good choice.

JT

Land almost anywhere without damage?

How is the SBXC designed to accomplish that?

Originally Posted by dr_sprocket

Land almost anywhere without damage?

How is the SBXC designed to accomplish that?

Mass and fuse/wing skin thickness.

Originally Posted by dr_sprocket

Why has the RnR SBXC dominated cross country RC soaring for so long?

I see some planes around that have about the same span but it seams that RnR has the secret formula or something.

The 5kg (11lbs) FAI rule applies to XC soaring, and the SBXC and MXC are designed to meet that weight including vario, GPS, etc. There are many higher-performance large gliders available, but many exceed 5 kg flying weight.
Also, a good XC glider sacrifices some performance for visibility at altitude, which is why XC gliders have a relatively deep chord and hence lower aspect ratio than higher-performance gliders.
They're relatively easy to land because of the relatively low wing loading, and good XC pilots find suitable LZs... : )

Dieter Mahlein, ShredAir

Originally Posted by dr_sprocket

Land almost anywhere without damage?

How is the SBXC designed to accomplish that?

Multi-function control with flaps. An experienced pilot can land an 11 lb SBXC with remarkable precision. Don't get the idea that they are bullet proof, but try to land a 4M Euro ship at something below Mach 2 sometime.

JT

Have any of you guys flown the new MXC?

Originally Posted by dr_sprocket

Have any of you guys flown the new MXC?

Yes. Think big Millennium. More chord than an SBXC so a bit easier to see at altitude. I find it a bit loggy close to the ground, but I have only flown a friends very early example of the MXC. The ship has evolved a bit through the first 5-10 that are in use. Of the 10 teams that flew California Valley, I believe 3 were flying the MXC, three flew home brews, the rest SBXCs.

JT

I have a 5m plane I bought a few years ago. Actually, WS is 15 or 17 depending on the tips. it's called a Condor. Seller said it was one of a kind.



Still don't have a good way to launch it. Nearest winch club is about an hour away. Does anyone have any tips about auto-towing one of these things?

Originally Posted by bigjohn

I have a 5m plane I bought a few years ago. Actually, WS is 15 or 17 depending on the tips. it's called a Condor. Seller said it was one of a kind.



Still don't have a good way to launch it. Nearest winch club is about an hour away. Does anyone have any tips about auto-towing one of these things?

We have successfully car launched while participating in the Soaring Safari. The appratus was a glorified hi-start (geez, I hate saying that anywhere on RCG). We worked out the vehicle speed and tested the gizmo at our club field. Launches were a bit higher than normal winch launch, based on Alti-2 altitude data.

25' of ~1/2" ID heavy wall tubing tied into a loop (use a Carrick Bend, a sailing knot) to form the loop so it can't pull out under tension, with a metal ring strung on the rubber before looping. 500' of winch line and a chute onto the ring. The rubber loop is mainly a shock absorber, though it will store a little energy for a zoom. We don't push the rubber too hard.

We lash the rubber around a trailer hitch, then the truck drives out until the line is deployed. Helper and driver are in communication, cell phones work fine, or FRS radios. On command the driver accelerates to 21-23 mph (no more) and helper throws the plane. At the top of the launch, helper tells driver to stop, pilot uses the stored energy in the line/rubber for a reasonable zoom (for an XC plane). Reel in the line and hit the road.

JT

Check this one out

http://www.rcgroups.com/forums/showthread.php?t=873174

Joe

how do you guys normally launch the SBXC's ?

dh

Originally Posted by dhauch

how do you guys normally launch the SBXC's ?

I have seen some guys hand launch them (sometimes with two hands) and I have assisted Don Richmond ROG his SBXC.

Ryan

Originally Posted by dhauch

how do you guys normally launch the SBXC's ?

dh

RC Cross Country Soaring (1 min 48 sec)