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aeajr
477 Posts |
 Posted - 05/21/2008 : 3:37:30 PM
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This is a reprint of the article that appeared in the June 2008 edition of RC Soaring Digest. www.rcsoaringdigest.com The photos can be seen in the RDSD version of the article.
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HAVE YOU LOOKED AT RES LATELY?
By Ed Anderson
Aeajr on the forums
Here is the path that many glider pilots take. They start on a typical 2 meter foam or wood rudder/elevator glider and find they enjoy soaring. Soaring is fun, it is relaxing and challenging all at the same time. You don’t need expensive fuel, electric starters and you don’t need big brushless motors and Lipo battery packs. And you don’t need all the support equipment that goes with this stuff. An inexpensive hi-start, a cheap radio, an open field and the energy in the air is all you need to join the birds. This is great stuff!
As is usual, once they get good with their starter plane, they want to move up. So they go to the club glider master and ask for advice on the next glider. “Oh, well if you really want to do it right, you should go to a larger plane because bigger flies better.” OK, no argument there.
“And you should get a full house glider and a real sailplane radio”, advises the soaring master. And so the excited pilot gets a 3M full house whatever. If he has enough money he may buy into one of the composite planes. He gets a hot shot sailplane radio too. This thing has switches and dials and mixes and flight conditions galore. Now he is going to become a soaring master by the end of the month!
In some cases this works out very well and in others, the complexity of the planes and the radios become a real challenge. A lot of money is invested and all of a sudden flying gliders has become complicated and expensive. And the soaring master says, “if you really want to launch that megaplane, you need a winch.”
What happened to easy, relaxing and low cost????? And if you break it, well now we are talking composites and bags and molds and a lot of money at risk. HELP!
This is nearly the path I followed. I actually had a couple of 2M RES gliders. I really liked them, but I wanted to be a real glider pilot so I moved on to a 3M full house sailplane plane and a 9 channel sailplane radio. While I struggled to get all this mixing and camber changing under my belt, I learned a lot about how to fix full house glider wings and fuselages. And finding and staying in lift was more demanding than when I was flying my Spirit. (Yea, I had my launch mix on when I meant to be in thermal 1.)
Of course there was RES but that was for those nostalgia pilots and the woody kit builders, not for me. I was going to fly unlimited competition. I had launch mixes and landing mixes and camber and ..stuff. And I had access to a club winch. I was beyond RES.
I am happy to say that, today, my usual flight routine skips the crashing phase. Camber changing and the like are now part of my daily flying routine. But it took awhile as I am not the sharpest knife in the drawer. And I did not practice as carefully and with sufficient focus to really get command of all these tools that were in my hands.
HEY BUDDY, LET’S TALK RES.
Sailplanes that are designed around rudder, elevator and spoiler controls were once the standard. They were the hot competition planes and they were the design of choice for most pilots. There were no computer radios so any kind of mixing for a full house plane had to be done mechanically. That was tricky and potentially troublesome.
However, with the arrival of affordable computer radios it became easier and less expensive to go to full house gliders. So going full house, rudder, elevator, aileron and flap, became more practical, and the path of choice for “real sailplane pilots”.
Somewhere in this evolution many of today’s pilots skipped RES sailplanes. They were considered “beginner” planes. Real glider pilots used ailerons and flaps, right?
Lately I have been reading about the new generation of RES ships. I also started seeing them show up at Eastern Soaring League unlimited sailplane contests, being flown against the full house ships. And the pilots who were flying them were not beginners. These were pilots who had full house ships and fancy radios. So, why were they buying and flying RES ships?
I can’t say for sure when this RES resurgence started, but it seems to have occurred around the time that Dr. Mark Drela introduced his Bubble Dancer RES sailplane. The Bubble Dancer was based upon a built up wood design and a carbon/kevlar spar. This spawned a whole family of related designs, which include the AVA, the Topaz, the Soprano and others.
To be sure, there are many R/E and RES planes of the past that have been great flyers, but I have not seen too many of them as gliders of choice at Eastern Soaring League unlimited class contests. But these new birds are showing up in the hands of experienced flyers.
These new generation RES gliders are very light, but they are not fragile planes. They can take hard launches yet are so light that their ability to float and hang in super light lift may give them a competitive advantage in light to moderate conditions. Add some ballast for those windy days and you can increase their penetration ability quite a bit.
Some of these high-end RES planes are using similar airfoils to the full house ships. And the bent wing RES design makes them supremely easy to manage at the edge of visual range offering the less experienced competition pilot the confidence to range out to work that fringe lift. And for a sport pilot, this is the fun, relaxed experience they fell in love with back on the R/E 2M glider.
So, I took the plunge and bought an AVA. Oh my goodness, what a wonderful experience. This is the feeling that got me involved in sailplanes in the first place. This is the easy flying, low-pressure feel that I fell in love with on my Spirit and my Sagitta 600. But this is a big plane and it launches like a competition plane. I like this experience.
My Supra and my Thermal Dancer both fly great and I love them. At 64 ounces and 59 ounces respectively, they have wing loading just under 9 ounce per square foot of wing area. They report and work lift very well. Using my sailplane radio I can reshape their wings in flight to do all sorts of neat things. I have no intention of abandoning these full house wonders.
But the AVA, and similar RES planes in this class, are working in the 35-50 ounce range with wing loading in the 5 to 7 ounce range. These are real floaters that can rise on a whispered wish or the byproduct of a franks and beans lunch. In calmer conditions, flying the AVA almost feels like cheating because it is so easy to sky the plane out. My friend’s Topaz has a similar feel. They are nothing short of amazing.
My full house birds need all of my attention all the time. By comparison, the AVA practically flies itself, leaving me more freedom to watch the air and the conditions. And since I don’t need launch modes, flight modes, camber modes or any other modes, I can’t make a mistake with my dials and switches. Fly smooth, pay attention, rise on the thermals, and just enjoy!
When the wind picks up, their very light wing loading can leave these planes feeling like leaves on the breeze. So, do you put them away? NO! You ballast baby; you add lead!
I wrote about ballast in last month’s RC Soaring Digest. Adding ballast increases the range of conditions these planes can fly. And adding ballast can increase the pilot’s confidence to work that lift higher and longer and further out.
The AVA, for example is typically in the 40–45 ounce range, depending on your equipment and options. Mine is 44 ounces with a center landing skeg, a ballast tube and a modified split spoiler that has two servos. This yields a 5.7 oz. wing loading on a 127” wing.
We had some gusty conditions last weekend with some over 10 mph. I was able to fly the AVA just fine, but with an added 9 ounces of ballast, it smoothed out nicely and rose beautifully in lift. This increased the model’s weight and the wing loading about 20% giving me a much more comfortable flight experience and better penetration without having to use a lot of down elevator to penetrate into the wind. I would not necessarily add this much ballast under these conditions, but this is what I had and I wanted to see how the plane would fly.
Since I plan to fly the AVA in a broad range of wind conditions I plan to make up a 16 ounce ballast package as well to take it up to 60 ounces, or about a 36% ballast load. However even at 60 ounces the wing loading is still under 8 ounces per square foot of wing area. I have heard of competition pilots adding ballast to over 50% of the plane’s weight for this and other RES planes in this class.
And ballast is not just for competition pilots. Any sport pilot who looks at a 10 mph wind and leaves the plane in the racks should start working with ballast. It will add a lot of flying days back onto the calendar.
WHAT ABOUT MY RADIO?
You can fly any RES ship on a simple three or four channel radio, like the Hitec Neon or the Laser 4. On a RES ship, in mode 2, you put the rudder on the right stick so you do all your flying with your right hand. You use the third channel, to raise the spoilers, which reduces the lift of the wings to help to bring the plane down to a nice landing. If you can control this on the left hand, you have the perfect combination.
Depending on the RES plane, you will probably need to add some up elevator to hold the plane more or less level or it will start to dive. With elevator compensation the plane can settle down on a flat glide for a nice controlled landing near you, or on the landing tape for points.
If you are going to buy a radio but are on a budget, most of the introductory computer radios have a flap to elevator mix built in. You will use it as a spoiler to elevator mix, which is the same thing but may need negative numbers to get the right motion. Having this one mix can make a RES plane supremely easy to land as the elevator compensation becomes automatic and you can focus on the plane. You won’t need all the other fancy mixes, flight conditions and the like that the full house glider pilots love to debate. With RES it is so simple to fly successfully.
Systems like the Spektrum DX6i, the Hitec Optic Sport and similar entry level computer radios have more than enough capability to bring out the best in your RES ship. And, while they are not real “sailplane” radios, they give you enough in options to get into full house sailplanes if you ever decide to go that path. Then you can lust for that 8-12 channel mega mixer, but for your RES glider you won’t need any of that fancy stuff.
Some radios may allow you to put the spoiler control on the stick while others put you on a dial. Some only offer you a three-position switch for closed, half open and fully open spoilers. While that may seem quite limiting, if you practice with it, that should be enough control for all but the most precise work. In fact some people prefer the 3-way switch because the response is known and consistent. If you have the option, being able to operate the spoilers with the left hand while you fly with the right is best. Again, I am assuming a mode 2 radio arrangement.
Even though I have fully variable spoilers I tend to deploy them at half and full most of the time. The variability just lets me ease them in, but I have a half way stop on my control so I can feel that mark. If you practice with those settings you will know how to use them and you can become quite accurate with your landings.
SPOILERS VS. FLAPS
One advantage spoilers have over flaps is that they raise the stall speed, the plane will stall at higher speeds than when the spoilers are closed. If you slow too much you can retract them, the lift of the wing will increase, and the plane will continue to fly. In this respect they are more forgiving than flaps.
With flaps you decrease the stall speed so you can slow the plane way down and keep flying. But if you slow down too much, pulling the flaps in will increase the stall speed and you may not have enough speed to keep flying. So, if you apply too much flap too soon, then retract, you may stall and drop. And if you do this at 20 feet you may not have enough room to pick up speed to reach flying speed again. Don’t ask how I know. (Yes, please put the pieces in the bag.)
I have tested this theory more times than I care to remember, unintentionally. It holds true every time. In my early full house experience I proved this over and over. My Legend has the scars to show for it. Combine this error with a high wing loading plane and you have a wonderful lesson plan for learning to repair wings and fuselages.
Net net, once you have flaps out and the plane slows, you may not be able to safely retract them. You don’t have this problem with spoilers. See, RES is simple and forgiving.
Now, the full house competition wizard enters and says, “ You know with the flaps on a full house glider you can slow that bird down real nice and just about walk it up to the landing tape to nail the best landing score. You got no flaps on a RES plane.” He strolls out with a smile.
Of course he is right. But with a plane in the 5-7 oz/sq. ft wing loading range, the plane already flies slow so there is little need to slow it down. I just float it up to the landing tape, pop the spoilers and put the nose down. In fact my first day out with the AVA I almost hit the spike at the center of the circle, twice. I have never done that on any of my full house planes.
WHAT IF YOU LIKE TO FLY IN CONTESTS NOW AND THEN?
If you like to fly in contests but don’t plan to accumulate a lot of specialized contest planes, RES may be your ideal plane. RES planes can be flown in most unlimited contests as well as RES specific contests. So one plane can be your contest plane for both.
If you build one of the wood RES planes then you can also fly in woody and maybe some nostalgia contests too. Check the rules, but wood planes like the Bubble Dancer are legal in contests like Wood Crafters, even though they have carbon in the spar. Build a Bubble Dancer and you can now fly woody, RES and unlimited with the same plane. That is something you can’t do with your 3M composite full house plane.
And there are kit makers like Polecat Aero, Skybench and MM Glider Tech that offer RES kits for very reasonable prices. And the AMA has a plans service available so if you like to build from plans, check with them. If you like to build, don’t overlook RES.
Many of the wood kits either call for carbon reinforcement of the spar, or can be modified to take it so you can fell confident making strong launches and get some pretty high launches without having an all composite plane. I can say my old Legend, with a carbon capped wood spar, can take a full pedal launch on our club winches. Wood is not just for nostalgia anymore.
Wood RES kits can get you into the running on a low budget. Now you have to practice! Whether you are flying wood, or one of the high-end composite RES ships, a well-practiced RES pilot can do pretty well in most contests. I have read many report of RES pilots scoring well or winning unlimited contests against full house pilots.
If the conditions are light and you have a light RES ship, you may be at a competitive advantage against the heavier full house planes. And if you have practiced with ballast, wind does not have to be a reason to drop out. So, don’t hold back, go challenge those full house guys and go for the gold!
TAKE A LOOK AT RES
Look around and you will see RES ships popping up like dandelions on my front lawn. They are fun, they are great flyers and they just might be the best next ship for your fleet.
RESOURCES
If you are not familiar with Spoilers, this article may be helpful:
www.skybench.com/report/spoilers.html" target="_blank">http://www.skybench.com/report/spoilers.html
Some of the RES planes and suppliers mentioned in the article can be found here:
Spirit 2M RES
www.greatplanes.com/airplanes/gpma0530.html" target="_blank">http://www.greatplanes.com/airplanes/gpma0530.html
Bubble Dancer
www.charlesriverrc.org/articles/bubbledancer/markdrela-bubbledancer-3m.htm" target="_blank">http://www.charlesriverrc.org/articles/bubbledancer/markdrela-bubbledancer-3m.htm
AVA
www.kennedycomposites.com/ava.htm" target="_blank">http://www.kennedycomposites.com/ava.htm
Topaz
www.soaringusa.com/products/product.htm?product_id=16708&category_id=293" target="_blank">http://www.soaringusa.com/products/product.htm?product_id=16708&category_id=293
www.skipmillermodels.com/topazs.php" target="_blank">http://www.skipmillermodels.com/topazs.php
Soprano
www.isthmusmodels.com/product_info.php?cPath=21_27&products_id=97" target="_blank">http://www.isthmusmodels.com/product_info.php?cPath=21_27&products_id=97
Skybench
www.skybench.com/" target="_blank">http://www.skybench.com/
MM Glider Tech
www.mmglidertech.com/" target="_blank">http://www.mmglidertech.com/
Polecat Aero
http://polecataero.com/products/ezbd
AMA Plans Service
www.modelaircraft.org/plans.aspx" target="_blank">http://www.modelaircraft.org/plans.aspx
(765) 287-1256, ext 506.
Discussions on RES Sailplanes
AVA and Topaz – Too Light?
www.rcgroups.com/forums/showthread.php?t=843256" target="_blank">http://www.rcgroups.com/forums/showthread.php?t=843256
RES or Full House – Which is Better?
www.rcgroups.com/forums/showthread.php?t=859132" target="_blank">http://www.rcgroups.com/forums/showthread.php?t=859132
What RES Planes Do You Guys Like?
www.rcgroups.com/forums/showthread.php?t=839959" target="_blank">http://www.rcgroups.com/forums/showthread.php?t=839959
Have you RESed lately?
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Best regards,
Ed Anderson
Long Island Silent Flyers
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mikel
106 Posts |
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aeajr
477 Posts |
Posted - 05/28/2008 : 3:44:50 PM
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Great link Mikel, I hope others will add similar links or will tell their RES stories.
Frankly I just rediscovered RES and can't understand why I ever put it aside.
See ya at the ESL contests.
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Best regards,
Ed Anderson
Long Island Silent Flyers
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Edited by - aeajr on 05/28/2008 3:45:11 PM |
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Have You Looked At RES Lately?
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