LAZY J's modified FT Versa build.

[LAZY J]

Hi all!

Thought I would share my latest build of the FT Versa...

With a couple of weeks of holiday leave up my sleeve and some time planned on the coast coming up I thought I would put together a nice simple flying wing for some slope soaring with a power pod to follow later (if it survives ).

Slope soaring is a real passion of mine with flying wings in particular being something I am all too familiar with... I have found a 100 different ways to modify the trusty Windrider Bee (with varying levels of success and failure), have played with Zagi's and Wild Wings... have spent hours combating, DSing and dune gooning... in short, this particular build is something I am looking forward to!

To be honest when I first started to look at the FT Versa I really did not think much of it - I instantly wrote it off as too draggy and inefficient due to its simple flat bottom aerofoil... still, with curiosity getting the better of me I watched a couple of videos of it in action and was very much surprised by its performance!

Although obviously a great fun soarer built stock, with the idea of this little wing sold I got to work hatching a plan to perhaps squeezing a little more potential out of her.

The list of mods to come is as follows:

Extend the wing as much as a sheet of foam allows for a slight increase in wingspan (adds around a couple of inches), wing area and aspect ratio.
Remove all internal paper to allow for a more traditional curved aerofoil.
Work towards manipulating the foam board a touch for a more semi symmetrical aerofoil.
Replace foam spars with full length 5mm balsa spars of a reduced height giving around a 5 to 10% reduction in aerofoil thickness.
Replace standard foamboard winglets with more efficient higher aspect ratio 3mm balsa winglets.
Bottom hinge the elevons using the RTV silicone hinging technique.
Use covering film for a nice smooth surface finish.

Although I am not expecting massive gains from the above mods the combination of multiple small efficiency gains should add up to a marked improvement in performance... or at least I hope!

So here is where I am currently - all parts are cut, internal paper yet to be removed but all required bevels sanded in (45 degree on wing leading edge and elevons, 15 degree on trailing edge).

 

[JimCR120]

Hello LJ!

When you say up the coast I suppose you mean the Aussie coast, yes?

Very nice details about your passion and the mods on the Versa. I'll be interested on seeing the developments. I assume you've heard of the Prandtl wing. I was hoping to incorporate some of that into my next wing though not as big as what the NASA guys do.

Welcome to the forum.
—Jim

 

[LAZY J]

Hi there and thank you Jim!

Yes, by coast I mean the Aussie coast... I currently reside in Brisbane and travelled south down the coast to a place called Cabarita. This is superb sloping territory with some great low dunes and some awesome headlands with one being an almost sheer 500 ft cliff! Unfortunately this time of year we experience strong off shore winter breezes so the chances of some serious slope time were limited.

One day was perfect but unfortunately was host to two wedding parties... I thought it best not to possibly scare the brides so cancelled that particular day. The second chance I got was pretty good for a maiden with some nice trimming flights but unfortunately was cut short as I will get to below.

In regards to that Prandtl wing I must admit to being not familiar with that particular design. I took some time to have a look and that is some pretty serious (and pretty!) work. From what I can gather they are hoping to manipulate the surface of the wing to adjust the mean centre of drag on each wing panel to counteract the increase of drag inherent in an increase of lift on the outside travelling wing (aka adverse yaw) negating the need for vertical surfaces?! That's some pretty heady stuff and I will be most interested in how you approach this in model form. In my experience flying wings have no advantage over the conventional sailplane plan form other than in the interest of simplicity and durability to be honest... still, I think the ultimate flying wing would be a super high aspect ratio plank (low to no sweep) with a slim profile and short boom with vertical surface. Something I have always planned to do but never got around to.

...not sure what it is about flying wings that makes it so easy to get yourself lost in the possibilities! haha.

So I can now report the Versa experiment has been a success with the maiden being pretty stress free. A tonne of lead in the nose as per standard for most flying wings (leading to a 17oz/500g AUW) and a quick few tosses on a football field to adjust the CG with it finally ending up around an inch rearward of stock (I prefer my wings to be as rearward as possible). This was then followed by some launches off a small headland as seen in the pics below.

As for the build here are some build shots leading on from my first post.

First is a shot of the resulting aerofoil section and 2300mah battery install with 2 x FT servos for control. In hindsight I should have extended the lower surface around another 10mm (ended up cutting the upper surface flush). Receiver hatch was cut into the bottom surface rearward of the spar after the wing panels were joined. Second shot is a mock up with panels joined, balsa high aspect ratio vertical surfaces added and finally sanded with 100grit ready for covering. Leading edge and centre section were taped with packaging tape to keep it as smooth as possible (has proved more than strong enough so far).

Covering was a combination of Hobbyking film, chequered race tape and sign writers vinyl. Two tips I can offer here for sloping (or any other foamy for that matter) is the use of RTV silicone for hinging and the use of everyday electrical tape along your leading edges! Silicone hinging is a super easy, strong and gapless hinging process. Electrical tape along your all important leading edges offers fantastic protection making it surprisingly resistant to dings and tearing... the added bonus is the ability to restore your leading edges at any time with a new layer of tape... try it, you'll be surprised!

In regards to flight behaviour I can honestly say the FT Versa is a great little wing. Setup as standard with a forward CG and plenty of reflex will result in a nice stable and slow wing for light lift. Moving the CG rearward in increments and reducing the reflex results in a wing on par with most other foamy slopers. As per most sloping wings a strong vertical band of lift rather than a light broad band and half pipe manoeuvres are where it will shine.

Unfortunately my flying was cut short before I could head to some higher sea side cliffs due to one of the servos coming loose. At first I put this down to the use of hot glue to secure them... upon later inspection during the following power upgrade I can put myself to blame here! Looking at the remaining servo I found it would not come away without some serious tearing away of the foam... looking at my wayward servo it looked as if I had not applied glue around the outside of the servo leaving only a small dab of glue doing the job under the servo!

So on that note I did not get any worthwhile video but here is a parting shot of her in her element:

Before I wrap this up and move on to the next powered stage I would recommend anyone thinking about soaring the FT Versa to give it shot! Wrap the leading edges in electrical tape, get the CG right with some dive testing and have fun. As for slope soaring the best tip I can give anyone is get used to trimming the aircraft so that you constantly have to hold a bit of back stick... this will make it far easier to keep your speed up and milk the fluctuations throughout the lift band.

 

[LAZY J]

The next stage of the Versa build after returning home was adding a power pod

First pic is of the hack job made for removal of the flight pack and lead plus the relocation of the receiver and placement of the ESC. A FT firewall was then cut down to shape and crudely secured with balsa bastions to be later further supported by the power pod.
To be honest I was a bit worried about placing the receiver between the ESC and motor but thankfully have not noticed any interference or glitches as a result.
The powerpod was made with foamboard, the paper was then stripped to allow for sanding round of all the edges and the whole shebang was finally coated in brown paper applied with a mixture of PVA diluted with water. This was finally covered in light weight spackle and sanded smooth. The tail pipe/ air exit is a small piece of alloy tube and also a bit of an experiment to generate a different sort of noise (following flight video makes me think it may have worked to some degree?).
The cowling idea as seen was eventually scrapped but something I may revisit if time allows.

The second photo is of the completed motor pod covered in film and also showing the battery hatch (electrical tape tab allows for easy hatch removal) alongside the intake scoops for battery and ESC cooling (they work great!).

The third pic shows the source of my scoops. Cheap and cheerful measuring spoons work fantastic and secure well with a bit of hot glue! Also you can see the scoop added that due to the low pressure airflow on the upper surface draws air from around the ESC below.

A couple of other mods seen below were the securing of the vertical surfaces with toothpicks and hot glue after removal of the contacting chequered tape (tore both off on the slope and resorted to tape due to relying purely on hot glue). I also salvaged some Corona MG servos and covers from a sailplane I totalled last season.

... and here she is ready to go with my other FT build (modified simple Storch).

Of course we need a flight video!

This is her second flight with the maiden being a complete non event with a half throttle hand launch and not a click of trim or CG change needed (got lucky I think! lol).

AUW is 450g/16oz minus battery (550g with the 1300mah lipo on board) with the trusty FT "C" size power pack adding the go and a 10x4.7 prop doing the pulling. Currently she is fast enough to be fun, has easy unlimited vertical and is super smooth from slow to fast.

All in all I am very happy with the way this one has turned out to say the least with the only changes I am looking to make is perhaps a cowling and the addition of a faster prop - ANY TRIED AND TRUE RECOMMENDATIONS FOR GO FAST PROPS ON THE FT "C" SIZE POWER PACK ANYONE?

Cheers all!