Product review: DW Hobby Rainbow flying wing V2

About

Ah! Its been a long time i haven't been reviewing a fixed wing model, lucky me they send over latest stuff from DW HOBBY models which is a delta wing or very known as flying wing.   I received this kit on the 6th October 2016 last year from Banggood.com took me sometime to gather some parts to build it that is because its in kit which only to be able to get it run by 2017 until i found proper micro size parts for it and most importantly a budget.  Honestly its kind of annoying to received it since it was in kit because i need to chuck out some money to purchase some necessary parts to get it running....money drain out of my pocket again just to test and review it...that's bad and the parts required for assembly are tiny. Checking out the package; the box deco is pretty neat, it reminds me of TECHONE products which comes it slim portable rectangular box.  Inside is colorful booklet, some parts, the models itself and balsa wood for the main body assembly which i don't like about it because instead of standard cavity to place the electronics into the EPP body like most flying does they used the balsa body to house the electronics which is not so aerodynamic implementation on a flying wing.  At the time of writing this wing consider the most affordable and cheapest flying model around USD$20 in kit form...of course i didn't mention about the shipping cost plus all those electronics but still its way cheaper to go since this wing only needed small quantity of parts to make it a complete set of ready to fly unit provided you supplied your own radio.  For your info this wing comes in two type of models depends how they were powered,  the "Pusher" type (rear propeller driven thrust) and the "EDF" type (Electric Ducted Fan type for jet thrust).  I got a "Pusher" type because EDF is just way pulling too much power and over kill to make it fly especially if you're a sloper fan at the beach...keep it classic and simple. At first before the build i didn't expect much fun or performance out of this kind of kit especially an EPP because based my experience EPP plane are slightly slower and wobbly performance than solid EPO type wing like the Z-84 and other fast planes...i used to fly EPP profile plane and they are fun flying Cow to fly around the park. So the box was left in the hangar for so long months until i manage get my feet back with proper parts then build and maiden the Rainbow Wing V2 .... i was wrong about the "cow" thing after its successful maiden flight...more true story to tell coming up next.

Specification (as describe by vendor/manufacturer)

Package included (kit form - assembly required):
1x Rainbow Flying Wing EPP kit
1x A bag of building parts (pushrods, propeller and etc)
1x Pieces of balsa parts template
1x Colored manual book
1x Some carbon spars

Build, flight performance and review.

Assembling the plane is pretty much straight forward process just like assemble 3D profile plane, i use mostly "ALTECO 110" super glue based on 'Thyl-cyanoacryl ester' chemical bonding to glue the parts in place which is suits best for EPP foam and for lightweight bonding than using hot glue.  This flying wing uses lot strips of carbon fiber spar to keep the wing straight and rigid.  One of the most annoying part of the build was trying to trying to fit the electronics hardware and motors under wooden balsa body case which is also part of the motor mounting housing, is way too narrow and small to fit everything under the wooden cavity box .  I have to use thimble thumb size ESC and radio receiver under the balsa housing and also use smaller size motor to seat properly behind the motor mount.  The stock factory motor angle was a bit awkward, it has more 'up' thrust setup than straight toward the back like any conventional motor angle style does on flying wing so there bunch of argument in the forum telling which is right and which is wrong but for me i'd keep it that way as defined by manufacturer manual. As for motor i salvaged from 5 years old DIY quadcopter model from Hobby King store probably rated at 2200kv, runs on 10A ESC with 5x3 GWS prop.  As for battery i lug in a RHINO 3s 610mah 20C li-po pack which common used on my 3D profile plane.   This wing is quite picky about the servo size, you won't able to fit standard size 9g servo which is way to big and also heavy if you concern about making a perfectly lightweight build flyer.  The most vital modification necessary or compulsory to do is to reduce the Elevon surface movement stiffness on both side of the wing.  The Elevon surface and the main wings are connected/bridged by a thick EPP form instead of using flimsy pivot or plastic pivot like any pro builded wing, the thickness of the foam that holds the Elevon makes it hard to flex around or pivot/swing up and down which will put more 'push and pull' stress load to micro size 4.1~5g  servo even for 9g type servo.  What i did to 'relax' or soften the Elevon movement was to use a pen knife and cut a straight line along the groove of EPP foam that bridged between elevon and wing surface leaving only 3x bridge of 1cm width size worth of EPP foam connected between them making it easier to flex around with less material bridging together. For Elevon control i ended up using micro size 4.1gram Emax ES9051 Digital Mini Servo that fit nicely (with some empty gap on servo place holder), strong enough to put torque pull on the Eleven control and light enough to keep it overall build float in the air.  Overall i manage to keep the full flying weight about average 156gram as measured using cheap digital weight scaler.

On its first maiden day i did had some few error launching it causes crashes on to the ground due to insufficient Elevon control to pull the flight surface which ended several cracks on the wing just behind  the servo place holder after face-plant on soft sandy beach which makes me realized how fragile this Rainbow Wing V2 can be.  The next day after gluing back the cracks and added extra EPA throw on my radio transmitter the maiden flight went successful with minor up Elevon click on the up trim button and off it goes straight into aerobatic maneuver.  Immediately i fell in love with the plane because it flew as commanded and as what i wanted to make it move in the air as i move my control stick around.  FYI i have dozen number of flying wing platform build to fly and enjoy around the park include ones that flew and glide around the beach but the RAINBOW WING V2 seems to have the attributes of every capability of my previously owned wing all into one small package.  It able to fly fast with minimal amount of thrust as shown in the video where i always keep my throttle max between 50~70% push only and have great vertical power.  Probably the slim narrow aero foil design all over the wing surfaces make it easy to break the air  and keeping forward motion with less wind resistance. Surface Elevon control seems to responded very well with less delay and the wing surface along the reinforced carbon spar doesn't flutter a lot when diving  high speed flight which usually happened on generic EPP type wings like my Hobby King Combat Wing (Red Eagle brand).  Overall no matter how hard i bash and flick a quick turn, barrell roll, loop and etc the RAINBOW WING V2 showed a great solid performer in the air.  When you demands for it the wing shows! Great!

The only down side of this plane is that its not as durable as any standard EPP based flying wing known to be used as general 'Combat wing' around the slope/cliff side to knock around with opponents unlike the TECHONE POP WING or TECHONE/HK BONSAI despite having the same design outline.  The EPP foam seems to crack easily between the servo area and the motor mounting which is where the most thinnest and vulnerable area if pilot tends to crash head-on into the ground. Even hand catching the wing seem to add in stress point on overall wing structure so i had to catch it gently. This plane is highly recommended for seasonal or advance R/C flyer who knows how to fly and land without crashing it.  For beginner R/C pilot best to look away and find wings with beefy foam all around that can withstand high impact or crashes.

About the flight time i generally getting between 5 ~ 7 minutes of  run time doing lots of speedy low passes, fast vertical aerobatic rolls and loops with throttle stick between 60~70% throw.  But if i were to cool down the throttle just gliding with the wind around the beach like a glider we're looking at about average 7~9 minutes.  All these flight time were performed on my small RHINO 3s 610mah 20C li-po pack which i used them a lot on my 3D profile plane.

Videos/Medias
Here are sample of video of  i posted on my Youtube channel contain test review on DW Hobby Rainbow Wing V2

• Product gallery:  DW HOBBY - Rainbow flying wing V2 kit (800mm) 
  • Video:  DW Hobby Rainbow Wing V2 - Fun flying day
  • Video:  DW Hobby Rainbow Wing V2 - Part 2 Test flight
  • Video:  DW Hobby Rainbow Wing V2 - Part1 unboxing and assembly

Vendor/seller

Here are list of reputable vendor/seller which i bought from and also verified by community forum discussion groups. Also i've experienced buying from these places that have good support and services:

Seller Banggood.com:  DW HOBBY Rainbow V2 Version 800mm Wingspan

Build parts (as recommended by manufacturer):

• Servo: Emax ES9051 Digital Mini Servo
• Motor:  1404 2900KV
• Propeller:  GWS 5x3
• ESC:  Red Brick 10A ESC or anything between 5~10A ESC rating
• Li-po Battery:  2s 200~400mah Li-po
• Receiver module (FrSky): FrSky D4R-II 2.4G 4CH ACCST Telemetry Receiver (on my radio combo only)

Support group:

Places where you can find help and resources related to this product:
Topic: Rcgroups.com - Dancing Wings RAINBOW Wing BUILD and review
Topic: Rcgroups.com - DW HOBBY Rainbow flying wing

Summary

If you manage to keep your build as light as possible then RAINBOW WING V2 is a whole new level of fun flyer.  Its small, agile, fast, can glide slow and very aerobatic capable plane well suited to any area to fly either at beach, sea side or park size area. If you're pro flying some aerobatic maneuver, flipping around in the air, some speeds and need portable size to put at the back seat of the car then this is for you.  For newbies who are into flying wing...hmmmm i guess you need to look for more beefy EPP wings to handle some crashes if you're clumsy enough.  The only part i don't like about about this Rainbow wing V2 is because overall structure down and under the fuselage was made out of balsa wood to house the electronics and as landing skid which more likely to break apart or detached after repeated flight.  Some forumer manage to DIY some improvement to fit their preferred setup to make it more robust and durable. If you already have this kit no worries because there's always lots of improvement to work on it if you're good with some crafty tools at home.  As for me getting old (lazy) prohibits me from some mods so i'd stick to the original setup cause it flies ok and fun unless i did manage to break it.  So what's my verdict on this flying wing?,  i'd give 6/10 rating for being structurally fragile but overall for being fun flying and highly maneuverable that matching my flying skills i'd give 9/10 rating for making my weekend a big smile.