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Gambler+ from Wright Brothers RC

Mitch Gerdisch enters the realm of magically powered planes with a review of the new discus launch glider from Wright Brothers RC. (Before and after video of launching this glider can be found in the HLG Pro Clinic video review!)

Splash

Introduction

My Gambler+ waiting for launch.
My Gambler+ waiting for launch.
Wingspan:48” (1.25m)
Chord:6” (15cm) at center
Wing Area:256 in2 (16.5 dm2)
Weight (as specified):6.3-6.9oz (179-193 g)
Weight (as built):7.4oz (210g)
Wing Loading (as specified):3.5-3.9 oz/ft.2 (10.8-11.7 g/dm2)
Wing Loading (as built):4.1 oz/ft.2 (12.7 g/dm2)
RX Battery:4-cell 270mAh NiMH pack (weight ~ 1.2oz).
Radio Equipment:Berg Microstamp RX; Hitec HS-55 servos.
Manufacturer:Wright Brothers RC
Designer:Allan Wright
Kit Price:$60

I’ve been flying R/C for about four years now and, up until recently, I could always see what was powering my plane – namely the motor and prop on the nose. But, this year I found myself being drawn into invisible power sources. It started with a slope plane -- the natural forces that keep it aloft continue to amaze me. But, I wanted to enter the realms of magical sources of power and that’s when I started thinking that I wanted to try hand launch gliders. After all, what could be more magical than using some sinews of muscle and Sol’s furnace to make a plane fly?

So, when the Gambler+ from Wright Brothers RC came available for review, I quickly threw my name in the hat. The Gambler+ is the discus-launch glider (DLG) successor to Allan Wright’s original Gambler, which was designed as a side arm launch (SAL) glider. The main difference between the Gambler and Gambler+ is that the original Gambler was a V-tail while the Gambler+ has a cruciform tail. The vertical stabilizer extends above and below the tail boom. This allows the lower part of the stabilizer to counteract the torque put on the upper part during the discus launch, such that no special presets on the transmitter are needed to keep the plane stable on launch.

Allan developed the Gambler+ with the beginning DLG flyer in mind. His goal was to provide a relatively inexpensive entry into DLG gliders for the novice. I personally think Allan has succeeded in achieving his goals. As you’ll read below, the Gambler+ is an absolutely complete kit that builds into an airplane with a large performance envelope in which the novice can learn, grow, and hone his/her skills.

The Kit

The kit is delivered in a well packed triangular shipping container. Upon pulling the kit out of the shipping box, one finds a package that actually looks more like a kite package than a model airplane kit. But, I guess in a way that makes sense.

The kit is very complete. It includes:

  • Full size plans,
  • Instruction manual,
  • Laser cut parts,
  • Carbon fiber boom,
  • Sheeting, dowel stock and trailing edge stock, and other wood items,
  • Exotic materials: carbon fiber rods, Iron-on carbon fiber ribbon, Kevlar thread, Kevlar cloth, fiberglass cloth,
  • Pushrods, Du-Bro connectors and control horns.

When I do the math, I’m amazed that the kit only costs $60. The builder only needs to provide glue, epoxy resin, tools, radio equipment and some time.

Construction

When it comes to balsa kits, I’ve built traditional die-cut kits as well as self-jigging laser-cut kits. The Gambler+ falls in between. Although the Gambler+ offers laser cut parts, it is not a self-jigging type of kit. It is more like a traditional balsa kit where building pins and sandpaper are your friends. As the following table shows, the total time for me to build the kit was not too bad, but this is not an ARF...it IS a built-up kit that takes some investment of time on the builder's part.

Construction Time Summary

Steps (as per Instructions) Amount of Time Needed (minutes) Notes
1–4: Fuselage and boom construction45
5-9: Wing hold down and fuselage tops/hatches90Skipped step 7
10-12: Shaping and attaching nose cone, and fiberglassing the fuse75Didn’t add the CF to the sides.
13-17: Center wing panel45
13-17: Right wing panel30Getting faster ...
13-17: Left wing panel20and faster.
18: Wing dowel30
19: D-tube assembly75Includes sanding/shaping the D-tube/LE.
20: Gluing the wing panels together30
21: Sheeting center of wing30Includes a bit of sanding.
22: Attaching wing hold down reinforcement and checking wing-fuselage fit30
23-24: Ironing on the CF ribbon60
25-27: Attaching the tailfeathers45Excluding covering.
28-31: Control linkages and radio equipment installationUntimedRadio installation time will depend partially on what equipment you use and how skilled you are at this part of the process.
32: Attaching launch peg10Done!
TOTAL620About 10 hours to build minus covering and radio installation. It probably took me an additional 6-8 hours to cover the plane and install the radio equipment.

Construction Details

The included instruction manual is extremely thorough with plenty of pictures. So, I’m not going to replicate it here. Instead, I will share some notes I made while going through the steps in the manual.

Steps 1-4: Attaching the Boom and Building the Fuselage

Yippee, the boom is pre-cut for you! The instructions imply it might not be, but it is. Also, when you take out the Kevlar thread, you may be tempted to think that it is a single piece that has come unraveled. This is not the case. There are three pieces of thread in the kit and you should only use one in this step.

Steps 5-6: Adding the Wing Hold-down Block to Fuselage

The instructions say to take a 1” piece of TE stock, then cut in half to make two 1/2” pieces to make a filler block behind the wing bolt block. Well, if you do this you will find that the filler block is a bit short when inserted in the fuselage. Instead, I inserted the TE stock into the fuselage and marked how long the pieces should be and then cut.

Also, don't fret, the kit includes a pre-tapped and CA-hardened wing hold-down block. This is one of those details that makes the Gambler+ a user-friendly kit to build.

Step 7 (optional): Adding a Javelin-throwing Peg.

Javelin-throwing peg? We don’t need no stinking javelin-throwing pegs!

Steps 8-9: Finishing the Fuselage

It wasn’t immediately obvious to me what the “3/16” x 3/16” hatch support” was. It turns out that it is found on the 3/16” (the thick one) laser cut sheet. There are actually two of them on the sheet. They are simple, rectangular parts.

Step 10: Shaping and Attaching the Balsa Nose Block

Step 10 is one of those big sanding jobs with which I generally have a love-hate relationship. I hate having to sand and shape big hunks of wood such as the nose block in the Gambler+. Yet, I also love how nice balsa is to work with and I love getting that final shape to appear out of what used to be merely a block of wood. But, it is a dusty, somewhat lengthy job requiring the builder to focus on the task at hand. Fortunately, although there are some other sanding/shaping tasks in later steps, the nose block is the biggest task as such. So, once the nose is done, most of your dusty moments are behind you.

Also, the instructions say to look at the plans to see in which direction the nose block grain is supposed to be. My copy of the plans did not provide this information. You can kind of tell from the pictures in the manual, but I also checked with Wright Brothers RC - the grain of the nose block should go in the same direction as the bottom sheet of the pod (i.e. a tail to nose orientation).

Steps 11-12: Glassing the Fuselage

I decided to glass the fuselage, but skipped adding CF ribbon along the sides. After glassing the fuselage, I felt it was strong enough for my purposes. Later flight tests proved it was strong enough. Well, I guess they were actually landing tests. Well, really, they weren’t landings as much as they were boinks. Anyway, the fuselage is plenty strong with the resin and fiberglass cloth.

One little trick I came up with in this step was to drill a hole through my building board (which is a ceiling tile and is easy to drill holes in) and then insert the tail boom through the hole to let the fuselage dry.

Steps 13-16: Building the Center Wing Panel

As stated in the instructions, the trailing edge of the ribs must be fully against the building board when glued in place. Furthermore, note that when you do this, the front part of the ribs will rise off the building board. This is OK and is expected given the airfoil used in the plane.

I removed all the ribs from the laser cut wood at one time and marked them lightly in pencil with their number (e.g. R1, R2, etc.). I used the plans as a guide, and this made the assembly steps easier. (Allan indicates that on all future kits the ribs are labeled by the laser, so this step is not necessary for those buying the model after this writing!)

Step 17: Building the Outer Wing Panels

Given how the outer wing panels are shaped and the angle between the ribs and spar, I found I had to widen the spar slot in the ribs a tiny bit to allow them to line up according to the plans. To do this, I simply used 240 grit sandpaper and took just a couple of swipes on the inside edges of spar slots in the ribs.

Step 18: Installing the Wing Dowel

I actually slid the dowel with the dowel support on it into the fuselage and then slid the center wing panel down onto the dowel support. I figured this would help make sure things were positioned properly.

Steps 19-20: D-Tube Sheeting and Wing Assembly

To make attaching the D-tube sheeting easier, I soaked them in some water. This allowed the sheeting to be bent around the airfoil shape of the ribs easier. Also, the water acts as an accelerator for the CA.

Also, when sanding the TE to match the airfoil, I put masking tape along the top of the ribs near the TE. This protected the ribs from stray swipes of the sanding block.

Step 21: Sheeting the Bottom Center Wing Bay

My version of the instructions had a misprint in them. It said to use scrap 3/32” pieces for the wing bolt area on the wing. It should have said to use 3/16” pieces.

Step 22: Installing Wing Hold-down Reinforcement and Checking the Wing-to-Fuselage Fit

Now that I had a couple of sheets of balsa on the bottom of the center wing panel, the wing did not sit in the wing saddle any more. As indicated in the instructions, I needed to sand the wing bottom and wing saddle a bit to get the fit nice and flat again. I needed to sand the wing saddle until the trailing edge of the wing sat flat on the bolt block.

Steps 23-24: Applying the Iron-on Carbon Fiber Ribbon

I don’t know what to tell ya, here. If you’ve never used iron-on CF ribbon before, I would follow the suggestion in the manual and do some practice runs on scrap wood first. You don’t want the iron too hot and it won’t work if too cool. With my Hobbico iron, I found setting the dial at the second tick seemed to work best. Regardless, I have some less than attractive spots along the wing. And, unfortunately, I used transparent covering. So, my poor building skills ended up on display for all to see. Fortunately, I hope to have this plane in the air more than on the ground. Who cares what a few hawks think of my building skills?

Step 25: Attaching the Vertical Stabilizer

Although I found using 3M77 very handy when glassing the fuselage, since the pieces of material used in this step are small, I decided to just use a glue stick instead. This allowed the Kevlar to be held in place and even repositioned as necessary, without having to deal with spraying.

Step 26: Attaching the Horizontal Stabilizer

Well, even after double and triple checking everything, I managed to attach the horizontal stabilizer a bit off kilter so that it was not square with the wing and perpendicular to the vertical stab. Let this be a lesson to you: quadruple check this step before gluing. The “good” news is that my horizontal stabilizer came loose after one of my initial flights. So, I was able to reattach the horizontal stab square to the vertical stabilizer and wing.

For the repair, I decided to use polyurethane glue (e.g. Gorilla Glue) instead of CA and it held up better. But it did break again. This time, the pylon itself broke just above where the Kevlar ended.

Which brings me to suggest a different approach than that in the instruction manual. When sizing the piece of Kevlar cloth used to hold the horizontal stabilizer to the pylon attached to the boom, I would cut a piece that not only goes around the boom and on both sides of the pylon as shown in the plans, but also folds up onto the bottom of the horizontal stab itself. This will add strength to the stabilizer-pylon attachment.

Editor's Note: Have to love a proactive manufacturer! Allan indicates that he likes Mitch's approach and all future runs of the instruction will be changed to include this recommendation.

Steps 27-29: Attaching the Control Surfaces and Horns

The only thing worth mentioning here is that in step 29, I got confused about which side to attach the rudder control horn. Because I had just completed step 28 and cut the slot in the boom on the left side, I was thinking "left" and attached the rudder control horn on the left side instead of the recommended right side (I’m a right handed launcher). Oh well, I decided to leave it as is since there is no interference between the two control surfaces or horns anyway.

Steps 30-32: Installing Radio Equipment

You'll need to install the radio equipment as per the instructions to get the plane to balance right. See the following section for some lessons learned with regards to batteries.

Control throws

Oops! The manual does not address control throws. In talking to Allan, he suggested 30 degrees for the rudder and 10 degrees for the elevator.

Some Lessons Learned: Receiver Batteries and Getting to the Proper Flying Weight

While building the plane, I kept thinking, “DLG = heavy forces = needs lots of glue.” As a result, I went through at least ½ oz of CA in building this plane. Add to this a rather poor choice in receiver battery packs (initially) and I ended up with 1/2oz of lead in the nose and a plane that weighed 8.4oz. This is 1.5oz over the upper limit of the specified weight range. So, let’s review a few things in the hopes that you can learn from my mistakes. After all, that’s what I’m here for.

My glue-o-rama approach was likely not necessary. The CF ribbon really will take the bulk of the forces at play in the discus launch. I think I could have easily saved ¼ oz by being a bit lighter on the glue. Also, I think I could have gone lighter on the epoxy resin when fiberglassing the fuselage.

Choosing and configuring a receiver pack is a place where relatively big weight savings are possible. Initially, I used a “classic” 270mAh NiCad receiver pack (like that sold with a Hitec radio). It weighs about 1.8oz and is made from some old technology (i.e. fat and bulky NiCads). Unfortunately, this pack along with my Berg Microstamp receiver couldn't fit in the nose of the plane. This forced me to move the receiver to a position under the wing. This also required adding ½ oz of lead to the nose to get the plane to balance.

I contacted Allan Wright about this. According to him, the plane really requires the receiver and battery in the nose to get it to balance without needing additional weight. So, he pointed me to some smaller cells that he said should fit in the nose easily. They are 280mAh NiMH cells manufactured by Tieg that weigh 8g (0.28oz) and are 14.5mm long, and 16.5mm wide. He also mentioned that I could use a Li-Ion cell from a cell phone pack. A single fully-charged Li-Ion cell charges up to 4.2V, which is enough for running the receiver.

I ordered a bunch of the Tieg cells from Balsa Products and made up a couple of packs in a side-by-side configuration and was able to get the RX and battery pack in the nose. Initially, I also kept about ¼ oz of lead in the nose as well to get it to balance on the spar. But, in various threads, Wright states that 3/8” behind the spar is OK as well. This is where my plane balances without the lead.. So, once I was comfortable with the plane, I removed the last bit of lead.

As far as covering is concerned, I thought about using Solite/Nelson Litefilm. I’ve used it before and it is very light but also rather fragile in my opinion. So, I decided to follow Allan’s advice for the covering and use Transparent Oracover from Hobby-Lobby for the wing and tail feathers and “regular” Oracover from Hobby-Lobby for the fuselage. This was the first time I had used the transparent Oracover and found it quite nice to work with. It’s thicker than Litefilm which I found made the Oracover easier to work with. And, the transparent Oracover appears to be tougher than Litefilm. But, I’m sure I paid a weight penalty using the Oracover instead of the Litefilm.

My final AUW with the Tieg cells and it balancing just behind the spar is 7.4oz. So, I ended up about 0.5oz over the upper end of the given weight range for the plane. But, I really don’t think it’s making much of a difference in the plane’s performance.

At the Flying Field

As per the instructions, I started out with some javelin throws to trim the plane out. Then, I went with some side arm launches (SALs). This the was the first time I had ever flown a hand launch glider and I found the increased height of the SAL over the javelin throw somewhat addicting. After doing SALs for a couple of flying sessions, I finally decided to try a discus launch.

Up until that time, my only exposure to discus launches was from some short videos I had seen. Not only had I never done a discus launch, I'd never even seen a discus launch in person. But, I decided it was time to try. So, I grabbed the launch peg, looked down towards the ground, and started turning around in a discus-launching sort of way. And, it worked. Although I still have a ways to go with respect to launch height, the discus launch technique is definitely more fun and, not surprisingly, gets the plane higher than using SAL or traditional javelin launch.

One of the great things about the Gambler+ is that it does not require any sort of presets on your transmitter to keep the plane stable during launch. Some planes require setting up a preset configuration (e.g. rudder trimmed and/or ailerons trimmed) that is then switched off after the plane is launched. The Gambler+ does not require any such switching from a launch mode to a flying mode. Any radio that supports at least two channels can be used without having to resort to getting help from a computer. I put together a short video of me flying the plane. There wasn’t much lift on the day the video was made, but from it you can get an idea of how the plane launches and flies. And, again, no presets were used.

Downloads

Conclusion

I've put a good deal of flights on my Gambler+ so far (hundreds of launches) and although I still have a ways to go in terms of improving my launches and thermal hunting, I've seen glimpses of what the plane can do and I can't wait until my skills can fill its performance envelope. And, this is part of what makes the Gambler+ unique in the DLG world. The plane allows someone to enter the DLG part of the hobby with a relatively modest investment. And, yet, it offers enough performance that the novice DLG pilot can learn and hone his/her skills without worrying about outgrowing the plane.

Going forward, I plan on improving my skills by flying the plane every chance I get. Also, I will be reviewing the new Handlaunch Pro Clinic training video just released by Radio Carbon Art that I hope will allow me to push the plane higher (stay tuned to the LiftZone for that review as well). Finally, I hope to enter some local HLG/DLG competitions so that I can pick up hints and tricks from more experienced pilots. I expect my Gambler+ will be leading me every step of the way.

Editor's Note: The HLG video review is now live! And includes before- and after video footage of Mitch launching the Gambler+.

Acknowledgments

A big thanks goes to Sal Carcerano (RCGroups handle: Sal C) for his help videotaping my flights and snapping the action shots.

Discussion

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Old Jul 25, 2004, 09:43 AM
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Michael Heer's Avatar
Stockton, Ca. USA
Joined Apr 2001
9,252 Posts
Hi Mitchell:
I very much enjoyed your review! Michael Heer
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Old Aug 17, 2004, 08:52 AM
Jeff Carr
Ft. Mill SC / Charlotte NC
Joined Mar 2001
2,633 Posts
Nice review

Allan is one very nice guy. Its nice to see someone who will adapt his model and plans set to accomadate everyone.

He is a class act.

Jeff
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