Ruby^tm Quick Start Operation Guide

Here is just the bare minimum instruction needed to immediately begin enjoying Ruby's essential benefits of assisted and autonomous flight and preflight check. It assumes that Ruby is installed and configured in your plane and you already have some experience flying model airplanes. See the complete Operation Manual to learn more about features and customization not described here.

Contents:

Safety, and Responsibility

Always assume the worst can happen.

While a Ruby^TM system that is properly installed, configured, and in good condition greatly reduces the chances of your plane crashing, it is still possible for your plane to crash. There's not much any flight stabilizer or autopilot can do if, for example, it or another critical component fails, the panic button is invoked in a dive too close to the ground, or strong winds overpower the plane.

Ruby itself is not bulletproof. Something as small as a drop of water in the pitot tube could prevent it from being able to keep your plane in the air on its own. There's also the possibility that you are presenting Ruby with an unusual set of circumstances that haven't been considered or tested yet, or that an error in design or code has escaped uThere's testing.

• Read the operating instructions carefully.

• Always be prepared to take immediate manual control.

• Don't fly beyond the limits or rules of conventional remote controlled aircraft.

• Carefully read and follow the AMA Safety Code. In particular:

• Don't fly over populated areas or anything you can't afford to crash into.

• Be sure that the plane is always kept within good range of the eyes, transmitter and receiver of you or someone on an active "buddy box".

• Do not allow children to fly without supervision.

For younger children and new pilots, it is recommended that an adult be in control during launch and land, control is only given to a to child once plane is at loiter altitude, and an adult is always standing by, prepared to grab the transmitter and assume immediate manual control.

As the operator, you alone are ultimately responsible for safe operation and bear all potential liability for damages or injury that may occur during operation, including those that may result from failure of any component, including Ruby.

Beware the Ruby-controlled propeller!

On the ground, the greatest potential for danger resides in the propeller and throttle. If radio contact between your handheld transmitter and receiver suffers loss or interference -or- if while in autonomous or altitude hold mode, your throttle control (usually the left stick) is not in the “off” position (usually the position bottommost / towards you), it is possible for Ruby to suddenly apply full throttle without warning in an attempt to climb back to loitering altitude. Although Ruby has safeguards to make spontaneous throttling unlikely, it's still possible, even when the plane is resting on the ground. Until you have moved the throttle stick to the "off" position and are certain that the plane is receiving your handheld transmitter signal clearly, always approach and hold the plane as if the propeller could be powered full speed at any moment. Make sure everyone around the plane is aware of this danger. It's a good habit to hold your thumb on top of the base of the throttle stick when you have the transmitter in hand.

Different transmitters use different channels for the throttle. If your Ruby is configured with the wrong channel for throttle, the propeller could spin as soon as power is applied to the plane. Remove the propeller or power to the motor whenever powering your plane with new or changed Ruby configuration or firmware.

Stay tuned for advisories

As Ruby is tested and used in new applications and conditions, we may find need to issue additional safety advisories. Make sure that we have a good email address for you in our mailing list (contact support@uthere.com to change your address), or check for the latest updated version of this page on the internet (http://uthere.com/products/ruby/warnings.html) often for updates.

The Modes

Ruby currently operates in three different modes: Manual, Aided, and Autonomous. The plane will respond very differently to your stick inputs on the handheld transmitter depending on the currently selected mode.

You normally select the mode using a two or three-position on your handheld transmitter. Typically, this is the "gear" switch / channel 5 on your transmitter.

To select various other than manual and aided mode, it may be necessary to flip this switch back and forth a specific number of times as indicated below. When doing this, start and end with the switch in the position furthest away from you. Count each time that you flip it towards you. Flip the switch in a "deliberate" motion, but don't pause more than a second between flips. Sometimes, if you flip the switch too quickly or slowly, Ruby will not count all the flips, so watch the plane's behavior to be sure that it's in the desired mode. If you have a 3 position switch, it doesn't matter if you flip all the way towards you (manual mode), or just to the middle position (aided mode), but flipping just to the center position will cause less thrashing of throttle and controls.

The modes are summarized in the Field Reference Card which you may want to print and take to the field.

If handheld signal is lost, Ruby will automatically enter autonomous mode.

Manual mode

In manual mode, the remote control simply behaves conventionally, as if Ruby doesn't exist. The joysticks on the handheld transmitter move the plane's control surfaces directly.

Manual mode is engaged by moving the gear switch to the position closest to you. Mnemonic: "Pull the switch towards you to grab direct control of the plane."

Aided mode

Aided mode is engaged by moving the gear switch to the middle position (or the position furthest away from you if you only have a two position switch).

In aided mode, Ruby essentially provides “cruise controls” or “training wheels”. Instead of controlling the plane's control surfaces directly, you now simply tell Ruby where you want the plane to go. Ruby can take care of airspeed, altitude, pitch, roll, heading or turn rate for you, or let you control them in a simplified way. A child with no prior experience can steer the plane around the sky intuitively without having to worry about hitting the ground regardless of what he/she does with the right stick. This is not just for beginners, however. It can be indispensable to expert pilots in situations such as degraded visual contact, fatigue from turbulence or instability, uncertainty about airspeed, difficult launching or landing, distraction on the ground, or an itchy nose.

Throttle stick = Climb rate or altitude hold

Altitude hold

When the throttle stick is pushed all the way forward, Ruby will try to maintain the plane at a particular altitude:

If you engage altitude hold above 75 feet agl, Ruby will simply lock the plane at its current altitude.

If you engage altitude hold between 25 and 75 feet AGL, Ruby will set target altitude to 75 feet AGL and climb aggressively to that altitude.

If you engage altitude hold below 25 feet AGL, Ruby will set target altitude to 400 feet AGL and climb aggressively to that altitude. In this way, aided mode can be used to assist hand launches.

Ruby will actively increase or reduce throttle to keep it very close to that altitude, regardless of maneuver, air currents, or target airspeed (elevator stick). It will coordinate pitch with its throttle changes so that airspeed remains constant. If you push the elevator stick forward to increase target airspeed, Ruby will automatically apply more throttle while maintaining altitude.

Climb rate / power

In any position below 95%, the throttle stick behaves as a conventional throttle, simply controlling the amount of power delivered to the plane. Ruby will change pitch as necessary to maintain target airspeed. Because of this, you can think of throttle as controlling climb rate exclusively, without being linked to airspeed as when you control a plane manually.

Pulling the throttle stick all the way towards you shuts off the motor completely and causes the plane to glide downward.

Pushing the throttle stick almost all of the way forward will yield maximum power and climb rate.

In this mode, if you push the elevator forward to increase target airspeed, Ruby will dive to reach that airspeed without changing throttle.

Aileron stick = Roll angle or heading hold

When the aileron stick is centered, Ruby locks onto the current heading, automatically banking the plane left or right to keep the nose pointed in the same direction.

When the right stick is deflected to the side, Ruby will maintain a fixed roll angle and turn rate that is proportional to the deflection. For instance, holding the stick all of the way over to the right will keep the plane in a steep 60 degree banked turn to the right. Holding it half way to the left will keep it in a gentle 30 degree bank to the left.

To change heading or to circle, get accustomed to holding the stick at a fixed angle rather than pulsing it as you would a conventional aileron in manual mode. Remember that under aided mode, the stick controls roll directly, not the roll rate. If your plane is being tossed around by heavy turbulence, it's best to just hold the stick at desired angle and patiently “trust” Ruby to ultimately bring the plane to that angle.

Elevator stick = airspeed

When the elevator stick is centered, Ruby will maintain a default cruising airspeed, typically about 25 knots for sport planes and 17 knots for gliders. Moving the stick pushed forward will increase airspeed, up to a maximum of 40 or 50 knots. Moving the stick all the way back will decrease airspeed down to a preset minimum airspeed just above stall.

Note that Ruby aided mode simplifies the control of climb rate and airspeed by isolating them. Whereas in manual control, the throttle and elevator stick can both affect climb rate and airspeed, in aided mode, throttle controls climb rate exclusively, and elevator stick controls airspeed exclusively. This separation of functions simplifies control, but can be a little counter-intuitive to someone accustomed to "shooter" video games or pressing on the gas pedal to make a car go faster. Isolating climb rate and airspeed is the way real pilots “manage energy”, especially when landing or soaring.

If you want to reduce altitude in aided mode, reduce throttle, and leave the elevator stick = airspeed alone. This will cause the plane to glide gently towards the ground while still maintaining an ideal airspeed, instead of diving with runaway airspeed. For this reason, you'll probably find that it's easier to make good landings using aided mode, especially in unsteady wind. You can trust Ruby to maintain airspeed regardless of your throttle setting or wind gusts. See the section “Landing: Aided Mode” below.

 

Moving the rudder (left) stick from left to right currently has no effect. It does not move the rudder.

Autonomous mode

If you have a three-position toggle switch on your transmitter, Autonomous mode is engaged by moving a three position switch to the position furthest away from you. Mnemonic: "Push the switch away from you to give all control of the plane to Ruby."

If you only have a two position switch, autonomous modes can be engaged by pulsing the gear switch as shown below.

Ruby will also enter autonomous mode if your handheld signal is lost.

In autonomous mode, Ruby takes complete control of your plane, but you can override controls by moving your control sticks.

There are three "submodes" which you can select by flipping the gear switch back and forth from the position furthest away from you:

 

• Loiter at current location and altitude

Ruby will loiter there in a circling, pacing, or hovering pattern, depending on strength of the wind, until you switch to a different mode.

To engage:

With a three position switch, simply flip the gear switch once to the position furthest away from you. If the switch is already at that position, flip it from furthest to middle or closest position exactly one time.

With a two position switch, flip the gear switch from furthest to nearest to furthest position high exactly three times, starting and ending at the furthest position.

Move the throttle to the full position so that Ruby can use anything up to full throttle if necessary to maintain altitude.

 

• Return to home and loiter:

Unless your battery is low, engaging "return to home" will cause Ruby to immediately head for thehome location that you designated at preflight (see below) and begin a climb or power-off glide to reach 350 feet altitude.

To engage:

With a three position switch, flip the gear switch from the furthest position to middle or closest to top position exactly 2 times, starting and ending at the furthest position.

With a two position switch, flip the gear switch from furthest position to middle or closest position exactly 4 times, starting and ending at the furthest position.

Move the throttle to the full position so that Ruby can use anything up to full throttle if necessary to maintain altitude.

 

• Perform autonomous landing:

To engage:

With a three position switch, flip the gear switch from the position furthest away from you to middle or closest position exactly three times, starting and ending at the furthest position.

With a two position switch, flip the gear switch from furthest to middle or closest position high exactly five times, starting and ending at the top position.

Move the throttle to the full position so that Ruby can use anything up to full throttle if necessary to maintain altitude.

Ruby will also automatically enter autonomous landing mode if contact with your transmitter is lost or the battery becomes low while in any other autonomous mode. Entering autonomous mode and observing whether the plane is loitered or flown towards landing approach is one way to use Ruby to check your battery.

Read more about autonomous landing below.

 

 

Controlling the autopilot

You can modify Ruby's behavior while it is in autopilot mode simply by moving the sticks:

Throttle

The position of the throttle stick determines the maximum throttle that Ruby is allowed to apply to maintain altitude or landing glidepath. Normally you will just push the left stick all of the way forward to give Ruby unlimited use of throttle when it wants it. Moving the stick all of the way back to “off” prevents Ruby from using any throttle, causing it to glide to earth while following the same loiter pattern over the ground as if it were still at 350 feet altitude. (This generally undesirable – it's not the same as auto-landing.)

A common mistake is to forget to move the throttle forward whenever autonomous mode is engaged. A worse mistake is to leave the stick all the way forward after the plane has landed.

WARNING: Make sure the throttle stick is in the “off” position when the plane is on the ground. If handheld signal has been lost, or Ruby is in autonomous mode and the throttle stick is not all the way off, Ruby may suddenly apply throttle to try to climb to loiter altitude and bring your plane home safely. Ruby knows to shut off the throttle if altitude is near the ground or plane seems to have stopped, but there are circumstances such as landing up on a windy hillside or unusually severe drift of sensors which will cause Ruby to mistakenly think that it's still flying.

Airspeed

Ruby will maintain optimal airspeed in autonomous mode, automatically increasing if necessary to make at least some headway against strong wind, and slowing down to hover over loiter point if strong wind makes this possible.. Move the elevator stick forward or back if you'd like Ruby to fly faster or slower than it normally would.

Roll

You can temporarily override autopilot direction by moving the aileron stick left or right. It will behave as in aided mode (see above) as long as the stick is not centered. Once the aileron is centered, the plane will turn back to its autonomous course.

“Panic button”

The gear switch can also be considered a “panic button” because aided or autonomous modes can often be used to quickly rescue your plane from a bad situation. As soon as you push the gear switch forward to the middle or furthest away position with sticks centered, Ruby will immediately try to level wings and establish sedate airspeed, even if you're spinning, stalled, inverted, or diving. Unless your plane is below 100 feet altitude, Ruby will also try to minimize the chance of structural overload by actively regulating wing loading as it pulls out of a dive. (Below 100 feet, Ruby will assume that chances and consequences of hitting ground outweigh the prospect of snapping a wing.)

Ruby can normally recover a plane gracefully from most airspeeds and attitudes without excessive altitude loss, but chances of irrecoverable situation ending in ground impact increase as you fly nearer to the ground. For that reason, you should try to keep training and stunts that might require a “safety net” above 200 feet altitude.

Remember that in order for Ruby to autonomously climb to safety from low altitude, you will have to push the throttle forward to authorize it to use throttle.

Preflight

(See the [video].)

(Preflight is summarized in the Field Reference Card which you may want to print and take to the field.)

At the beginning of each flying session:

• Turn on handheld transmitter.
• Move throttle stick to the “off” position.
• Connect power in the plane.
• Confirm that the plane can be made to operate correctly in each mode:

Flip the gear switch to the position closest to you to enter manual mode. Confirm that all control surfaces move smoothly and in the correct direction as you move the joysticks. Moving the right joystick to the right should cause the right aileron to go up and the left aileron to go down. (If you don't have ailerons, moving the right joystick to the right will cause the rudder to move to the right.) Moving it forward should cause the elevator to go down.

If you have a three position gear switch ,flip it to the middle position to enter aided mode. Confirm that Ruby is moving the ailerons in a way that would roll the plane to maintain a fixed heading,, and that it's moving the elevator in a way which will keep the nose pointed down about 30 degrees.

Flip the switch to the position furthest away from you to enter loiter mode. Confirm that Ruby is moving the ailerons in a way that would maintain level wings or a gentle bank angle, and elevator moving in a way which will keep the nose pointed down about 30 degrees.

• To tell Ruby where you'd like it to loiter and land ("setting home"):
  
  
  • Place the plane on the ground at the exact location on your field / runway where you'd like it loiter and land, pointed in the desired landing direction.
  • Flip the gear switch to the position furthest away from you (autopilot or aided mode).
  • While holding your aileron/elevator joystick in any corner (i.e. bottom left), flip the gear back and forth between furthest and middle or closest position exactly five times. You should end up with the switch back in the furthest position. Ruby will immediately wag all control surfaces at once to acknowledge. Be sure to let the stick go back to center position now. Wait five seconds while Ruby performs a preflight check. Ruby will then indicate with aileron or elevator whether or not the position was stored and it's OK to fly (see below). If the elevator wags up and down, the landing direction and location were successfully recorded to permanent memory and the preflight showed all systems ready for flight.
    
  • Warning: Be sure that Ruby's loiter and land position is a desireable one and not i.e. your crowded pit area. If you do not tell Ruby where you'd like it to loiter and land and a previously stored position is not nearby, Ruby will use the position at power-up or last preflight.
• Ideally, to really be sure that all systems are configured and working correctly, perform a quick "test before first flight".
  

After every battery change, and ideally before each flight:

It's not necessary to perform the above step every time the battery is changed. The home location and direction are stored to permanent memory. It is however necessary to perform a "preflight" every time the battery is changed, and preferably before every flight. It just takes a few seconds:

• Move the gear switch on the handheld transmitter the position farthest away from you for "aided" or “autonomous” mode.
• Make sure your plane is stationary, with pitot tube shielded from any wind. Unlike the above procedure, the plane doesn't have to be level or located at desired landing location or direction.
• While holding your aileron/elevator joystick in any corner (i.e. bottom left), flip the gear back and forth between furthest and middle or closest position exactly three times. You should begin and end with the switch in the position furthest away from you. Ruby will immediately wag all control surfaces at once to acknowledge that it is commencing preflight. Be sure to let the stick go back to center position now.

The plane will now re-zero sensors, removing any drift that might have occurred since last preflight.

Ruby will also check critical systems to tell you if it's OK to fly.

In about 5 seconds, it will wave control surfaces to indicate the status of the plane.
(If you have the expander plugged in, its red and green lights will continuously indicate the plane status).

If the aileron and rudder wave to the left, or the red light blinks alone,
DO NOT FLY. (Mnemonic: It is shaking its head “no”.)

If the aileron and rudder wave to the right, or both the green and red lights blink while the plane is stationary, the plane can be flown with caution, but Ruby may not be able to fly it, or the battery may be getting low.

The specifc problem causing the "Do Not Fly" or "Caution" is indicated by the number of wags of the aileron and rudder or flashes of the lights. See the Field Reference Card for a table.

If just the elevator goes up and down, or the green light blinks alone, all systems are good. (Mnemonic: It is nodding “yes”).

If Ruby nods the elevator 5 times, the plane is within 30 feet the "home" location that it will return to and land at in autonomous modes. If you see this while the plane is still in the pit area, it's a bad indication that you'll need to correct by taking the plane out to a safe landing spot and "setting home" as described above.

If Ruby nods only 3 times, the plane is more than 30 feet away from home / landing location.

You can move the gear switch to the aided or manual position and takeoff!

If you're not able to get "All systems are good" indication:

• Check that airspeed / magnetometer, gps, and motor power sensors are plugged in
• transmitter turned on
• fresh battery   (be sure Ruby is configured to expect the voltage of battery that you're using. By default this is 3 cell / 11.1 volts)
• GPS blinked when first powered up, but is no longer blinking (meaning that it has successfully acquired satellites)

Preflight will not end with an "OK to fly" indication unless the GPS has acquired a fix. When the fix is acquired, the red light on the GPS module will stop blinking, and Ruby will make the servos come to life as the plane is moved if you're in aided or autonomous mode. Outdoors, a wait of a minute or two after power up is typical if the GPS has not been used for several days. About 10 to 30 seconds is typical otherwise. If you're still having difficulties acquiring GPS, see [Troubleshooting GPS].

If you've checked off all the above and haven't found the problem, please send a copy of a data recording file from the sdFlash to us at support@uthere.com, and we'll probably be able to tell you exactly what's going on at a glance. (When we make the PC software available, you'll be able to tell yourself.)  

Takeoff

Because it automatically manages airspeed as well as pitch and roll, Ruby's aided mode can make runway and hand launch takeoffs easier, even for experts.

• Make sure the plane is pointed in the desired direction / lined up with the runway or path that you wish to initially want the plane to take. This should be into the wind as much as possible.
• Move the gear switch to center position to enter aided mode (not autonomous).
• Move the aileron stick to one side briefly, then re-center to lock the heading.
• To be certain that Ruby aided mode is working properly it's a good idea to rock and pitch the plane for a moment and see if control surfaces are moved appropriately.
  See "Test before first flight".
• Smoothly move the left stick all the way forward to enagage altitude hold mode and apply full throttle.
• For hand launch: Wait a second or two for motor to reach maximum RPM. Do not launch if the motor does not sound like it is at full power. Throw the plane as you normally would, generally forward and slightly upward.
• For runway takeoff: When plane reaches sufficient airspeed, Ruby will automatically raise the nose and begin climbing.
  
• Gently move aileron left or right if necessary to change heading as plane climbs. Steep turns should be avoided at lower altitude.
• You normally won't move elevator forward or backward to change airspeed during takeoff. Ruby will maintain an optimal airspeed well above stall.
• When the plane reaches 350 feet, it will level off and maintain that altitude unless you pull the throttle back from the 100% = altitude hold position.

To abort takeoff: move the throttle smoothly to off position. Move the aileron to left or right if necessary to keep the plane lined up with the runway. If plane is already airborne, refer to the last part of “Landing” instructions below.

Landing

Aided mode:

Aided mode makes landing easier by managing airspeed, energy, and heading hold, allowing you to simply adjust glideslope with throttle, and crab angle with touches of the aileron.

• Note which way the wind is blowing, and plan a landing into the wind as much as possible to minimize landing groundspeed.
• Put the plane in aided mode if it isn't already.
• Steer the plane into a good position for final approach. This will depend on plane, but will be roughly 75 feet altitude at 500 feet range for a sport plane and 50 feet altitude at 500 feet range for a glider. Circle and adjust throttle to climb or descend if necessary to target altitude. Apply some flaps if available and necessary to steepen glideslope and allow lower airspeed.
• If the wind is coming partly from the side, be sure to “crab” the plane into the wind so that it maintains a course in line with the runway.
• Adjust throttle until it appears that plane is descending on a slope that will end at desired touchdown point.
• If you find yourself too high even with throttle completely off or in a glider, you might use the aileron control to make gentle “S” turns to shorten the glidepath a little. Depending on the wind and characteristics of your plane, you might also be able to use the elevator control to steepen the glidepath by decreasing airspeed.
• As plane gets within about 5 feet of ground, you might gradually pull back the elevator to “flare” the plane, reducing airspeed and descent rate, floating the plane over the runway until touchdown. Unlike conventional landing, it's OK to pull the elevator all the way back. This will tell Ruby will fly at minimum airspeed above stall. Note that small wind gusts can cause stall at low airspeed, so it's best to let Ruby fly at normal cruise airspeed (elevator centered) until just above ground to have wider margin above stall. On very gusty days, you might land with elevator a little forward.
• Move the throttle to smoothly zero as you reach desired touchdown spot.
• Be sure to the throttle is stick all the way off before handling plane.

To abort landing, move the throttle forward smoothly to apply full throttle, and refer to “takeoff” directions above.

Remember that in aided and mode, the elevator stick controls speed. It doesn't directly control pitch, so it's can't be used very effectively to “hop” or “spike” the plane to avoid hitting an obstacle. If you can't avoid an obstacle by moving aileron to turn laterally, switch briefly to manual mode.

Autonomous landing:

Autonomous landing puts the plane on the ideal glidepath from the beginning. You can use this mode to line yourself up for the perfect aided or manual landing, or you can simply let Ruby take it all the way to touchdown.

Autonomous landing mode is entered by flipping the gear switch three times, starting and ending in the autonomous position. The plane will immediately steer towards an ideal final approach entry point in a direction that you determined when you performed preflight. When the battery drops to 10.7 volts while Ruby is in autonomous mode, it will attempt an “auto land”.

Remember that unless you stored a fixed home point in permanent memory, Ruby will land at the location and point in the direction of the plane at the time of the most recent preflight. Enter aided mode to abort the auto landing if this is your pit area!

Be sure to push the left stick all the way forward when you initiate auto land. This will authorize Ruby to apply throttle as necessary to reach ideal entry point and follow desired glideslope.

When beginning “auto land”, Ruby will by default first fly about 600 feet from landing point and enter what it believes will be the ideal final approach glideslope, typically about 75 to 100 feet above ground. It will circle or pace while climbing or descending to that entry point if necessary. [More info about Ruby's autonomous landing pattern.]

After reaching final approach, Ruby will do its best to keep plane lined up with runway and maintain straight glideslope to target touchdown point.

Ruby does not currently actually detect proximity or contact with the ground - it thinks it's always flying and a little drift in the barometric altimeter or slope in your landing field can lead Ruby to believe it's still a few feet off the ground when it's not. So, as the plane gets within a few feet of ground, move throttle stick to "off" position. This is necessary to prevent possible damage to propeller, motor, or ESC as Ruby tries to climb back onto glideslope.

Helping Ruby to land

Ruby can usually make a fairly good landing on its own, but with your assistance, a gentler and more accurate touchdown is possible.

The main issue is that it's common for the pressure altimeter to drift by as much as 20 feet during a long flight (5-10 feet more typical). An alternative ground ranger (i.e. sonar or optical) is not yet available. Not knowing precisely where the ground is, Ruby just descends slowly until it makes contact.

You can help Ruby to make a softer landing by smoothly pulling the elevator stick all the way back to reduce airspeed to minimum as the plane gets close to the ground, starting about five feet above the ground. You can help it to make a more precise landing by smoothly moving the throttle to “off” as it gets close to your desired touchdown point.

Ruby is usually able to use GPS to bring its landing path laterally within 5 – 15 feet of target, even in crosswind, but if course modification is needed, you can always override the autopilot by moving aileron from center.

Be sure the throttle stick is all the way off before handling plane.

 

To abort landing, switch to aided mode and move the throttle forward smoothly to apply full throttle. Refer to “takeoff” directions above.

Remember that in autonomous and aided modes, the elevator stick overrides target airspeed. It doesn't directly control pitch, so it can't be used very effectively to “hop” or “spike” the plane to avoid hitting an obstacle. If you can't avoid an obstacle by moving the aileron to turn laterally, switch briefly to manual mode to perform the maneuver.

Warnings, "gotchas", and Tips

Avoid "home" being anywhere you wouldn't want the plane to land

If you don't set the home position as described above in "setting home", Ruby will use the home position that was last stored, but only if it is less than a few hundred feet away from its position at first GPS fix after power up and if that home position has been set since firmware was last updated. Otherwise, Ruby will simply default to the position of first GPS fix after power up. This can lead to a dangerous situation if you first applied power someplace like a crowded pit area, since Ruby would try to land there in auto-land mode.

To be sure to avoid such a situation, always pay attention to how many times the elevator wags at the end of preflight. If it wags 5 times, you are less than 30 feet from the home / landing target which is a bad indication to see in the pit area, but a good one to see if the plane is where you want it to land. It will wag just 3 times if you are more than 30 feet from home / landing target.

Changing trim on your transmitter during flight

Putting in more than a little trim during flight can cause Ruby to think you're holding the stick in a deflected position to constantly turn or fly at a different airspeed. In autonomous mode, this can cause Ruby fly in endless circles and drift downwind. [more info]

Return to home mode triggered by lost radio contact

If radio contact is lost even briefly while in aided mode, Ruby will automatically enter "return to home" mode (or "auto land" mode if battery is low).

If your mode switch is in the "manual" position, Ruby will go back manual control as soon as signal is regained. This can be a dangerous "gotcha", since Ruby may reenter manual mode without your realizing it. If Ruby has entered "return to home" mode due to signal loss, be sure that your mode switch is in an aided or autonomous position, or be prepared to resume manual control at any moment.

If your mode switch is in the "aided" position, Ruby will remain in "return to home" mode even after radio contact is regained. As always, deflecting your aileron stick from center will temporarily override autonomous mode and cause it to respond as in aided mode, but when the stick is returned to center, it will steer back towards home or final approach rather than in a straight line. To get Ruby back into aided mode, simply move the switch momentarily away from the aided position, then back to it.

The ultimate panic: Shutting off your transmitter during flight

Moving between modes using the toggle switch can be hard to do in a panic. Sometimes it's not clear to Ruby that you've made a "flip" that should be counted. It's often necessary to observe the behavior of the plane to confirm that it has entered a desired mode such as "return to home". Simply throwing the switch forward to aided or "loiter at current position" should give you enough time to regain your composure and calmly move to "return to home" mode, but certain unusual situations such as having put in transmitter trim during flight can cause it to circle and drift downwind instead of holding a heading or returning home.

If you find yourself in a complete panic with your plane having flown out of visual range, and yourself unsure of how to get it into "return to home" mode, your best option of last resort may be to simply turn off the transmitter. If (and only if) your failsafe has been configured correctly, this will cause Ruby to unconditionally enter "return to home" mode. It will return the plane home and circle until you reassume control, and it will commence an auto-land once the battery becomes low. You can reassume control at any time by turning your transmitter back on and flipping the mode switch momentarily to "manual" mode.

If Ruby's GPS or other sensors are compromised and preventing it from navigating it back home, Ruby will shut off power and attempt to bring the plane to earth as gently as possible in a slow spiral descent, holding controls at fixed positions if the IMU is not functional. If you're able to regain good enough visual contact to fly the plane manually while the Ruby is in this state, turn your transmitter on and fly it back in manual mode.

You should do all you can to avoid situations in which you end up turning off your transmitter. Ruby greatly reduces the odds of a bad outcome, but there are circumstances in which Ruby cannot prevent a crash.

**Note: Some transmitters / receivers are not able to reconnect after the transmitter has been shut off. It's also possible for your failsafe configuration on your receiver or Ruby to be incorrect, making Ruby oblivious to loss of signal. Be sure to test the behavior of your system when the transmitter is turned off and then on again.

 

What's next:

See the complete Operation Manual for additional features, ways to alter Ruby's behavior from that described above, high performance usage tips, and interesting insights into its technology.

There's a great deal of potential designed into Ruby hardware that has yet to be unlocked. Visit http://uthere.com often for free firmware downloads containing new and improved functions, and to learn about upcoming add-ons that will open new worlds of technology to you.