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E-flite Ultra-Micro 4-Site BNF Review

Ever dreamed of having a fully 3D capable biplane that's as easy to fly in your own living room as it is in a gym? Then let's take a look as Tim Tworek explores the new world of micro-3D aerobatics with the all new E-flite Ultra-Micro 4-Site BNF.



E-flite's Ultra-Micro 4-Site BNF
E-flite's Ultra-Micro 4-Site BNF
Wingspan:15.2 in.
Wing Area:87.5 sq. in.
Weight:1.10 oz. (w/o battery), 1.25 oz. (w/battery)
Length:17.5 in.
Wing Loading:2.06 oz/sq. ft.
Cubic Wing Loading:2.64 oz/cubic.ft.
Servos:(2)1.7g Linear Long Throw Servos
Transmitter:JR X9303
Receiver/ESC/Servo:AR6400L DSM2 ultra micro 6 ch. receiver
Battery:E-flite 1s 150 mah (12C) lipo
Motor:8.5mm Coreless Brushed (included)
Available From:Horizon Hobby
Retail Price:(BNF)$169.99
Retail Price:(PNP)$109.99

Who would have thought that just a few short years ago that micro r/c technology would grow to be as popular as it is today? I was amazed a couple of years ago when I flew my first sub-5oz. indoor foamy that could fly 3D aerobatics just as well, if not better, than my giant scale airplanes. OH HAVE TIMES CHANGED!! E-flite has revolutionized the way we perceive micro airplane performance and capabilities with their all new E-flite Ultra-Micro 4-Site BNF biplane. Designed by David Payne, the new E-flite Ultra-Micro 4-Site BNF breaks all the traditional boundaries and limitations of micro airplane performance and handling. The Ultra-Micro 4-Site is a do-it-all fully 3D capable micro machine that comes built and ready to fly right out-of-the-box. Just as the ad says, you can truly have this plane ready to fly in the time it takes to charge your battery packs.

The Ultra-Micro 4-Site has only one limitation... the pilot’s skill level. The included stock electronics and power package provided with the Ultra-Micro 4-Site will give even the most die hard 3D/aerobatic flyer a pure adrenaline rush as he performs his favorite 3D maneuver with a plane that weighs in at a mere 1.25 oz. The Ultra-Micro 4-Site is offered conveniently in both a BNF version (which includes the Ultra-Micro 4-Site,(2) 1s 150 mah (12C) lipo batteries, E-flite's Celectra™ 4-port charger and AC adapter) or a PNP version (which includes the Ultra-Micro 4-Site but does not include the charger or additional battery packs).

I have to admit that this was the video that really piqued my interest in the Ultra-Micro 4-Site and its extreme capabilities:

<a href=><b><i><big>Click Here!!</b></i></big></a>
Click Here!!

Kit Contents

My E-flite Ultra-Micro 4-Site arrived in excellent condition thanks in part to a very nicely foam-padded box that has a great picture of the actual model on the box top. I was very impressed with the care that was taken to protect the Ultra-Micro 4-Site through the use of foam blocks and some masking tape which literally locks the Ultra-Micro 4-Site into the box. The Ultra-Micro 4-Site's box also serves as a great traveling case for the airplane: It has a built in handle at the top of the box that allows for easy and safe transport to and from your flying site. I could find no warping or any other damage to the model. For such a small and lightly built airplane I was very impressed that all of the control surfaces and the general structure of the airplane was straight and true.

The one thing that will strike you right away about the Ultra-Micro 4-Site is the highly visible and appealing covering scheme. The scheme shows up great in most any gym or outdoor lighting environments and will definitely catch the eye of anyone around you as you're flying. Here's a good video from the designer, David Payne, from the Horizon Hobby website talking about some of the innovative features and qualities found in the E-flite Ultra-Micro 4-Site.

The E-flite Ultra-Micro 4-Site BNF contains:

  • Completely built and RTF Ultra-Micro 4-Site airplane
  • Preprinted uniquely stamped foam construction
  • (2) 1s 150 mah (12C) lipo batteries
  • E-flite’s Celectra™ 4-port charger and AC adapter
  • Pre-installed AR6400L Long Throw ultra micro receiver/ESC/Servo
  • (2) Long Throw Linear aileron servos
  • Pre-installed 8.5 coreless brushed motor and 130mm x 70mm prop
  • Carbon fiber pushrods and bracing
  • Optional speed brakes

The E-flite Ultra-Micro 4-Site BNF requires:

  • 5+ channel 2.4 GHz DSM2 capable radio
  • Charging the batteries

Item used to complete the Ultra-Micro 4-Site BNF:

  • JR 2.4 GHz X9303 radio

The Ultra-Micro 4-Site Manual

The E-flite Ultra-Micro 4-Site comes with a brief but informative instruction manual. It doesn't need an extensive manual - there really isn't anything to build or assemble. The biggest items that the manual covers are how to bind your DSM2 radio to the AR6400L receiver and properly setting up the control throws, rates and CG.

As with most products found on the Horizon Hobby website the Ultra-Micro 4-Site manual can also be downloaded in PDF format. This is great for those people wondering what it might take to get the airplane ready to fly and what equipment (in this case radio) might be needed. This is also a great option for those people who might be receiving their Ultra-Micro 4-Site secondhand from a friend or fellow club member who does not have the manual.

Binding Setup

As mentioned above the Ultra-Micro 4-Site requires a DSM2 compatible transmitter in order to bind to the 6 channel AR6400L receiver unit. Here are the transmitters that are DSM2 compatible:

  • Spektrum DX6i
  • JR X9303 2.4 GHz
  • Spektrum DX7 and DX7se
  • JR 12X 2.4 GHz

PLEASE NOTE: The Spektrum DX6 (SPM2460) is equipped with DSM and NOT DSM2 technology, and therefore, it is not compatible with the AR6400L receiver in the Ultra-Micro 4-Site.

Unlike most binding practices with Spektrum receivers, the AR6400L doesn't require the use of any type of binding plug or even any type of contact with the receiver unit. Here's the simple steps needed to bind to the AR6400L receiver unit (using a JR X9303 tx):

  • Select the model memory you want for the Ultra-Micro 4-Site.
  • Plug in the 1s 150mah (12C) lipo battery and ensure the LED on the AR6400L is flashing.
  • Move the sticks and switches on the tx to the desired fail-safe positions.
  • Press the bind button on the back of the tx while turning the tx on.
  • The LED on the AR6400L should go solid red once the system has connected.

THAT'S IT!! That's all there is to binding the AR6400L receiver. It really doesn't get any easier than that.

Ultra-Micro 4-Site Features

Spektrum AR6400L Receiver

Type: ultra micro rx with integrated brushed speed controller and two linear servos
# of Channels: 6 channels or 4 channels plus X-Port
Modulation: DSM2
Band: 2.4GHz
Dimensions (WxLxH): 27.75 x 23.45 x 8.10mm (1.09 x 0.92 x 0.32 inch)
Weight: 0.14oz / 3.9g
Voltage Range: 1-cell LiPo 3.2V to 4.2V
Antenna Length: 31mm

Normally this would be the section of the review where I would explain the build of the airplane, or how I installed the servos or power setup, or how I glued on or attached the control surfaces etc.... but in the case of the Ultra-Micro 4-Site, all of that has already been done for you at the factory. Instead, I'd like to point out some of the great features that designer David Payne incorporated into the E-flite Ultra-Micro 4-Site.

The E-flite Ultra-Micro 4-Site arrives with the brushed geared motor already installed. The motor is mounted in a robust plastic radial type mount that is glued to the nose of the airplane. The motor/mounting setup definitely adds some stiffness to the front of the airplane (which I can attest holds up quite well under less than perfect landings or those slightly miss coordinated rolling circles).

The ailerons on the Ultra-Micro 4-Site are powered by two pre-installed 1.7g linear long throw servos. The upper and lower ailerons are connected with carbon fiber pushrods. The aileron servos are capable of giving the Ultra-Micro 4-Site very high throw rates which will please even the most experienced 3D pilots.

The Ultra-Micro 4-Site comes with a set of light weight carbon fiber landing gear that works great on smooth surfaces like that of a gym floor. I've been very pleased with how well the landing gear has held up through the numerous flights that I've put on my Ultra-Micro 4-Site.

The rudder and elevator on the Ultra-Micro 4-Site are operated by servos that are directly mounted on the AR6400L receiver/ESC/servo unit. The Ultra-Micro 4-Site's rudder and elevator pushrods are made of carbon fiber rod and small metal Z-bends that connect to the plastic control horns. The metal Z-bends are adjustable allowing for the accurate neutral alignment of the rudder and elevator control surfaces. The controls on the Ultra-Micro 4-Site operate very smoothly, and I've been very impressed by how well the control surfaces center overall using the stock onboard electronics.

Control Throw Setup

Ultra-Micro 4-Site Features

Spektrum 1.7g Linear Long Throw Servo

Type: Analog
Application: Ultra micro aircraft
Torque: 2.8 oz of force
Speed: sec
Dimensions (WxLxH): 22 x 16.9 x 8.2mm (0.87 x 0.66 x 0.33 in)
Weight: 1.7 g
Gear Type: Nylon
Voltage: - 4.2V

The E-flite Ultra-Micro 4-Site manual recommends two different dual rate and expo settings depending on the pilot’s experience level: an intermediate 3D pilot setting and an advanced 3D pilot setting. I decided to set my Ultra-Micro 4-Site up with the advanced 3D pilot settings. The only thing that I ended up changing over what the manual recommended was the amount of expo. I found that the recommended expo. was a little low for what I'm used to flying with normally. Of course this will vary depending on each pilot’s skill level and flying style, so using the recommended settings is a great place to start. Below are the dual rate and expo. settings I have setup on my Ultra-Micro 4-Site.

My CG was right at the manual-recommended 40mm setting which is measured from the leading edge of the top wing at the center of the fuselage. To me, this setting works out great for both 3D and precision flying with the Ultra-Micro 4-Site.

Dual Rates
Low Rates UpLow Rates Down High Rates Up High Rates Down
Elevator 65% 65% 100% 100%
Aileron 60% 60% 100% 100%
Low Rates Left Low Rates Right High Rates Left High Rates Right
Rudder 60% 60% 100% 100%

Expo. Settings
Low RatesHigh Rates
Elevator 30% 45%
Aileron 35% 50%
Rudder 35% 45%

IMPORTANT NOTE: When setting up your radio, do not set your ATVs over 100%. If the ATVs are set over 100% it could possibly overdrive the servos and cause damage to the servos.

Time To Fly!!!!

Basics Including Taking Off and Landing

E-flite Celectra 4-port (.3A) Charger

Type: 4-Port 1-Cell 3.7V 0.3A DC Li-Po Charger
Input: 4 D-size batteries or optional E-flite AC to 6VDC 1.5-Amp Power Supply
# Cells: 1 to 4 single cell Li-Po
Battery Type: Lithium Polymer
LED: 4
Experience Level: No Experience Necessary

I have to admit that the E-flite Celectra is a pretty cool little charger for the Ultra-Micro 4-Site. It allows the charging of (4) 1s lipo batteries. The Celectra charges at a rate of .3A so you can charge (4) 1s 150mah battery packs in about 30 minutes or less. The Celectra is super easy to use, and the LEDs indicate the charge status of the packs.

  • Solid red LED means the pack is charging.
  • A blinking red LED means the pack is nearly fully charged.
  • When the red LED goes out the pack is charged and ready to use.

For the ultimate in portability, the Celectra can run on either (4) D-size batteries (not included) or it can run on the included 6V 1.5A AC/DC power supply. I think it's time for me to buy a few more batteries!!

The Ultra-Micro 4-Site was made to fly indoors!! While I have yet to fly it outdoors, the Ultra-Micro 4-Site is nearly dwarfed by the size of our indoor flying facility. Our indoor flying facility is nearly the size of 3 high school gyms put together which makes flying indoor foamies a real dream. The Ultra-Micro 4-Site will easily ROG (rotate off ground) on pretty much any smooth surface such as our gym floors and become airborne at about half throttle. On low rates the Ultra-Micro 4-Site feels very well balanced and incredibly stable throughout the speed envelope. I was very impressed by how well the Ultra-Micro 4-Site tracked around our gym and how much the Ultra-Micro 4-Site felt like a bigger airplane. The Ultra-Micro 4-Site tracks just as good as my larger 4-Site F3P foamy if not slightly better. The Ultra-Micro 4-Site is capable of flying at extremely slow speeds, and I was impressed that the controls felt very positive at such extremely slow speeds.

The rudder on the Ultra-Micro 4-Site is very effective, but with the proper expo. set isn't overly sensitive. I found that I was able to fly sustained KE flight using only the advanced low rate rudder settings. There is some KE coupling on the Ultra-Micro 4-Site but not nearly what I was expecting for a biplane. I ended up putting in approximately 6% roll mix and 6% pitch mix to counter a slight pitch to the belly. With the KE mix programmed KE circuits could be flown with throttle and rudder only. Inverted flight with the Ultra-Micro 4-Site is a breeze. With my CG set at 40mm I needed just a slight push on the elevator to maintain level inverted flight.

The Ultra-Micro 4-Site comes with optional speed brakes that tab into place on the back of the outer plane struts. The best way to ensure these stay in place is to apply a small amount of CA and hit it with some kicker. I will tell you from experience that if you lose a speed brake in-flight you will notice it. The amount of drag that one of these speed brakes creates is quite substantial for a plane that only weighs 1.25oz. I have found that the speed brakes definitely slow the Ultra-Micro 4-Site down and greatly improve downline braking and overall top speed. For those pilots that fly in small gyms I think the speed brakes are a great option. However, I have also found that flying with the speed brakes on will reduce your overall flight time since higher throttle application is needed, and the speed brakes slow down the roll rate some. In our large gym, I have found that I enjoy flying my Ultra-Micro 4-Site with the speed brakes removed which allows me to take full advantage of the roll rate and the most flight time obtainable. Using the 1s 150mah (12C) lipo batteries I'm averaging around 5 minutes of mixed 3D/precision and around 4-4.5 minutes of flight time with the speed brakes installed.

Landing the Ultra-Micro 4-Site is a breeze. With as slow and stable as it flies there are no worries when it comes to slowing it down even further for landing. All it will take most of the time is just to keep a little throttle till you are a few inches off the floor and slowly apply enough elevator to lightly touch the mains to the floor. It really doesn't get any easier than that.

3D and Precision Aerobatics

I have to admit that ever since I watched David Payne fly his Ultra-Micro 4-Site on the Horizon Hobby website I had wondered if it was really that good of a 3D/precision aerobatic performer or if it was only capable of flying that well in the hands of the designer. While I may not be as talented of a pilot as David, I can tell you that indeed the Ultra-Micro 4-Site is a tremendously capable aerobatic performer.

WOW! flip the high rates switch, and hold on to your transmitter, folks. This is where the Ultra-Micro 4-Site really comes to life. This little plane was custom made for off the wall (literally) aerobatics. Ever want a micro flyer that was as well coordinated and every bit as stable and exciting as your favorite outdoor aerobatic airplane? Well then the Ultra-Micro 4-Site might just fit that ticket. I found out right away that the Ultra-Micro 4-Site is a pure rolling machine. Most indoor foamies do not roll like my GS airplanes. I struggle with getting the right rhythm (sometimes referred to as “the stir”) during rollers for lightweight indoor foamies. Most foamies need very little rudder/elevator input during the rolling sequence. However, I became immediately comfortable with the way the Ultra-Micro 4-Site rolls. It feels very much like my GS airplanes in a roller, and I was EASILY able to maintain a solid rolling circle after only a few attempts with my Ultra-Micro 4-Site. The Ultra-Micro 4-Site rolls great in both directions but tends to roll slightly quicker on inside rollers than on outside rollers. I'm extremely pleased with the roll rate on the Ultra-Micro 4-Site as it keeps my fingers quite busy during the rolling maneuvers.

The Ultra-Micro 4-Site also really excels at snapping maneuvers. This is one area in which most indoor foamies normally do not excel because of there light weight. Most indoor foamies will wallow through a snap. Not the case with the Ultra-Micro 4-Site. It snaps quite cleanly at moderate throttle settings and actually doesn't lose too much momentum even during KE circles with snaps thrown in.

The power package setup on the Ultra-Micro 4-Site is definitely not lacking in any power. It easily provides enough power for sustained hovers with the Ultra-Micro 4-Site. There is a tendency for the Ultra-Micro 4-Site to start to torque roll some during high power applications in a hover but the effective ailerons are quick to counter any unwanted torque rolling. The Ultra-Micro 4-Site is super stable in both upright and inverted harriers, and I found that with my slight increase in aileron expo. I was able to take out any tendency to wing-rock (finger induced).

I think the one thing that shocked me the most about the Ultra-Micro 4-Site was how durable this little plane is. While flying a roller, I lost sync, and the little Ultra-Micro 4-Site went straight in, landing directly on the spinner. Resulting damage... none. I simply powered back up, and away she flew. Because of its light weight, an accidental crash into a wall or ground will usually result in little to no damage to the airplane. The Ultra-Micro 4-Site also benefits from its pressed foam construction which not only improves the flight characteristics of the airplane but it also seems to be a little more robust than flat depron foam.

Is This For a Beginner?

No, the Ultra-Micro 4-Site is not for the beginner pilot. It's recommended for advanced skill level pilots who are comfortable flying highly aerobatic airplanes in an indoor or outdoor setting.

Photo Gallery

Flight Videos

I'm fortunate enough to be able to fly indoors in a great facility and one that several past and present ETOC competitors also fly in. A couple of those competitors just happen to be past ETOC champion Andrew Jesky and the up and coming young Ryan Clark. I asked both of these talented pilots if they wouldn't mind taking a few flights on the Ultra-Micro 4-Site and with zero hesitation both of them eagerly agreed. I'd say that from the smiles on their faces after each flight with the Ultra-Micro 4-Site that they were as pleased with the airplane as I was.

Below are a few videos of Andrew, Ryan, and me showing off the full capabilities and flight performance of the E-flite Ultra-Micro 4-Site.



So does the E-flite Ultra-Micro 4-Site live up to all the hype? I would have to say without a shadow of a doubt, YES. Its performance envelope is by far one of the best I have ever seen/flown on a micro flyer, and the Ultra-Micro 4-Site flies much bigger than the 1.25 oz. weight indicates. It can easily be flown in an area as small as a basketball gym, and I'm sure it would perform quite well outdoors on those calm summer nights. The Ultra-Micro 4-Site's power system pulls it through the most advanced freestyle routines with ease and comes back asking for more.

If you have ever wanted to explore the world of a true 3D-capable micro flyer the Ultra-Micro 4-Site will not disappoint in any aspect. It tracks as well as any F3P precision indoor flyer yet possesses the power and control authority to perform extreme 3D aerobatics. With flight times in the 4-5 min. range and the ability to quick charge the packs with the Celectra 4-port lipo charger, you can enjoy flying your Ultra-Micro 4-Site all day long. I have a feeling that my other indoor airplanes just won't be seeing much flight time this year thanks to the E-flite Ultra-Micro 4-Site.


  • Pretty much RTF right out of the box
  • Great looking preprinted color scheme
  • Excellent power/electronics package that performs as advertised
  • Awesome flight performance and 3D capabilities
  • Durability


  • None
Last edited by Angela H; Jan 11, 2010 at 07:04 PM..
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Jan 19, 2010, 06:05 PM
Registered User
Kmart's Avatar
That thar' be some flyin'!

Great review, perfect timing! Mr. UPS should be pullin' up any minute!
Jan 19, 2010, 06:10 PM
Registered User
tenzb's Avatar

Great review Tim!

Jan 19, 2010, 06:22 PM
"Because I was pǝʇɹǝʌuı"
bighead93's Avatar
So you like it more with or without the airbrakes?
Jan 19, 2010, 06:29 PM
Test your IMAC!!
sun.flyer's Avatar
Originally Posted by bighead93 View Post
So you like it more with or without the airbrakes?

Here is the quote from the review:

However, I have also found that flying with the speed brakes on will reduce your overall flight time since higher throttle application is needed, and the speed brakes slow down the roll rate some. In our large gym, I have found that I enjoy flying my Ultra-Micro 4-Site with the speed brakes removed which allows me to take full advantage of the roll rate and the most flight time obtainable.
In my indoor flying area I really enjoy flying the Ultra-Micro 4-Site w/o the airbrakes on.

Definitely a terrific flying little airplane.

Jan 19, 2010, 06:31 PM
Test your IMAC!!
sun.flyer's Avatar
I'm sure a lot of folks have seen this but if you have not Seth Arnold shows that the Ultra-Micro 4-Site can be flown inside a small apartment. Sweet flying Seth!!!

Ultra-Micro 4Site (3 min 5 sec)

Jan 19, 2010, 06:36 PM
"Because I was pǝʇɹǝʌuı"
bighead93's Avatar
Originally Posted by sun.flyer View Post

Here is the quote from the review:

In my indoor flying area I really enjoy flying the Ultra-Micro 4-Site w/o the airbrakes on.

Definitely a terrific flying little airplane.

I missed that! I only flew mine with them on...have to take them off...vertical was lacking just a bit! BTW...I tried the 120 14C from the MSR...really nice but you only get about 3 1/2-4 mins max. Really feels floaty on those!
Jan 19, 2010, 06:39 PM
Test your IMAC!!
sun.flyer's Avatar
Originally Posted by bighead93 View Post
I missed that! I only flew mine with them on...have to take them off...vertical was lacking just a bit! BTW...I tried the 120 14C from the MSR...really nice but you only get about 3 1/2-4 mins max. Really feels floaty on those!
You will definitely notice an increase in roll rate and flight times with the speed brakes removed.

The speed brakes are great for those people looking to fly the 4-Site as slow as possible in smaller spaces.

Jan 19, 2010, 07:29 PM
Pants on the ground
xsubsailor's Avatar
Great review Tim
Jan 19, 2010, 07:29 PM
Make the best of all you have
beetyii's Avatar
Well done Tim.


If you want to slow down your 4-site try this instead of the speed brakes :

Jan 19, 2010, 07:39 PM
Test your IMAC!!
sun.flyer's Avatar
Originally Posted by xsubsailor View Post
Great review Tim
Thanks Glenn!!

Great idea Rolf, thanks for posting that.

Jan 19, 2010, 08:05 PM
Watts up ?
OzparkPilot's Avatar
Mine arrives tomorrow - I got it purely to fly inside my living room. Cant wait
Last edited by OzparkPilot; Jan 19, 2010 at 08:10 PM.
Jan 19, 2010, 09:11 PM
Full throttle and supersonic!
Admiral14's Avatar
Wow! Great review Tim. You must be one of the best reviewers here. I know this little bird isn't for me just yet but your review has certainly made it all the more interesting.

Jan 19, 2010, 09:49 PM
"Aircraftus Fragmentum"
kydawg1's Avatar
Nice job.
Jan 19, 2010, 10:35 PM
Test your IMAC!!
sun.flyer's Avatar
Originally Posted by Admiral14 View Post
Wow! Great review Tim. You must be one of the best reviewers here. I know this little bird isn't for me just yet but your review has certainly made it all the more interesting.

Thank you, I appreciate the positive feedback. Glad to hear you enjoyed the review.


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