|Jan 30, 2013, 10:48 PM|
You Sir.. should be awarded a Phd on the subject of Quads.
In fact, the info is so comprehensive I dont see how a Grad wouldnt use it (steal it, LOL!) for their final thesis.
Being new to Quads, I will have to read this many more times to even begin comprehension because right now Im just at a point of "TMI"..
Thank You doesnt even begin to describe the appreciation for you efforts, which ultimately are to everyone's benefit.
|Feb 07, 2013, 09:58 PM|
TUTORIAL 11 --- X830 ---
AFTER THE CRASH…………….
Yes, it is going to happen. Maybe not today but someday you are going to crash that baby and have the sick down in the gut feeling of total despair and disbelieve. How could this have happened?
Once the really devastating crash happens with much of the copter destroyed many find it hard to continue with this hobby and begin to wonder if they should go back to flying something more forgiving and familiar to them. This is called the “Crash and Burn Syndrome”.
First you go back and relive the crash over and over again trying to figure what you did wrong, why you did what you did and visualize the affects of those actions. Let’s list some of the most common causes of multicopter crashes in no particular order;
1. Loss of orientation due to distance
2. Loss of orientation due to fast high speed maneuvers loosing reference of copter close in or far out
3. Onboard failure of components such as esc’s, props and wiring issues
4. Loss of radio due to range or weak Tx, bad Rx antenna mounting etc…
5. But the most common is over confidence.
I’m sure many will find other reasons but I believe these cover the most common problems.
People, it all comes down to having our head at all times in the upright and locked position when piloting our copters. We must always be vigilant, we are the test pilots and each time we spin up those rotors we are improving our skills, surpassing past limits and expanding our horizon of knowledge.
These steps must be taken slowly and with a watchful eye/ear not only listening to the copter but the visual IQ’s the copter gives in handling and viewing. We must also be wary of the weather conditions and people around us along with obstacles to avoid and where they are located in reference to our copter position at all times. In other words we must always be ahead of the copter!
If you are flying with the copter you are just a passenger not a pilot. You will not be able to react quick enough to avoid situations which lead to crashes.
What to do when the “C” word happens?
First you need to keep your wits about you and make sure no one was injured and no damage was done, well other than your pride. Next pick up the pieces after first completing a post crash survey of the area. Take the time to visualize the flight understanding what you did wrong and/or what occurred during the crash of the copter. This will be important down the road in rethinking, redesigning and reconstructing certain aspects of your copter for better crash survivability.
After you get the copter home you will need to do a complete dis-assembly of the copter. That’s right; you will need to take your copter apart down to bare bones. Why? How do you know other parts are not hair line fractured, bowed, stressed, missing, jammed along with pinched or exposed wiring internally? Without a complete dis-assembly you may have a hidden gremlin just waiting to pounce after you have your finished bird back in the air.
As you disassemble the copter label each component or wire so you know where it came from and where it attaches. Believe me later on you will be scratching your head if you didn’t. It’s also nice to draw out a diagram and label part locations.
Once all parts are disassembled you can inspect them for damage, bowing or fractures. A magnifying glass really comes in handy here. With the X830 the motor mounts under the motor bells are real suspect on hard crashes. They can bend ever-so-slightly but be enough to cause heating and high amp use. Always compare the mounts with known good mounts.
Make sure you thoroughly clean each motor. You may need to take them apart. This is an easy task and one you should get well acquainted with. The motor has a small Jesus clip underneath that needs to be removed from the shaft. Remove the 2 set screws on the prop side of the shaft. Once this is done a good pull on the bell will pull the bell housing off the motor. Inspect the bearing located on the motor bell and on the stator. These should be replaced if dinged or not turning smoothly. You should also replace the bearings at the end of each full flying season under normal use.
You can buy these bearing from Boca bearings. The X830 motors use a 4x9x4mm bearing. Always try to upgrade your bearings to the better bearings when you replace them and always replace both bearings. Boca Bearings is easy to work with and will help you by email if needed to choose the right replacement type. Here are some good links to help you with your motor needs;
RC BRUSHLESS MOTOR BEARING MAINTENANCE & INSTALLATION
TIPS FOR REMOVING SHIELDS & SEALS
RC BRUSHLESS MOTOR BEARING REPLACEMENT
RC BRUSHLESS MOTOR BEARINGS LISTED BY MODEL
Just a quick word on propellers, replace them! After a major crash replace the blades even if they look fine they were under tremendous stress, g’s and rpm’s when you hit the ground. Check the hubs, you may not see any damage or cracks but best to be safe and replace. If the old props show no hair line cracks inside or outside the hub mark them for very limited use only with minimum weight copter configuration.
See Tutorial 3 part 1 for more information on motor and propeller maintenance.
While we are on the Drive System of the copter don’t neglect a good examination of the battery. Look for the obvious bending, cracks, indention's or loose connector. The Lipo is a great advancement in battery technology but is more sensitive to crash damage. If the battery has as a small pinhole puncture which goes unnoticed it can burst into flames, sometimes many hours later.
Close inspection is not only advised but should be mandatory after any crash. If any punctures are found or the battery looks deformed with small bubble or bubblish bowing discard the battery.
As Jengaling always says, bullet connectors are one of the many deadly sins on-board copters. While you have your copter apart it is the perfect time to rid yourself of this culprit. Bullet connectors use spring action to lock themselves into the female connector. Issues I have found over the time of owning X830’s are loose fitting connectors and connectors not soldered fully causing intermittent opens otherwise known as gremlins. These gremlins usually hide inside arms and under electronics where they are not detected during visual inspections. Bullet connectors can be easily pulled apart if not careful.
To rid yourself of this gremlin you will need to cut all bullet connectors and female connectors off and solder the wires together. The advantage of this is no more wiring issues. The disadvantage is it’s harder to replace the components if needed.
Other alternatives include;
You can use high quality gold connectors which are very tight fitting connectors and will not come loose under normal use conditions or loosen up over time.
You can use the poor mans solution without removing the connector. Check that each connector has a solid solder connection to wiring. Take each bullet connector and put a small solder bridge from male to female connector. Once solder cools check connection tight and will not pull apart easily then use shrink tubing to seal the connections.
While we are on the subject of wiring this is a great time to take your Rx connector wiring to the controller and from controller to escs and braid. This should be done to all your video equipment wires along with ferrite rings to complete the wiring fix. The reason to take the time doing this is to cut RFI/EMF noise issues for your FPV equipment. See tutorial 9 for more information.
WARNING: When testing live electronics all propellers should be removed from motors.
You must test your FC system completely after a major crash to insure that the controller is functioning correctly in all modes and no loose sounds are coming from inside the controller when you do the shake test. If some functions are not showing operational in test screens available on the FC site then do not open to try to fix. Micro miniature soldering may be required so it is best just to box it up and send back to dealer if they work on your type of FC. If not, it is a gamble to try to send it back to China. It’s not the companies but the Chinese postal service to blame. Many FC’s of different Manufactures have been mailed back only to sit in a post office for 6-12 months then sent back to the customer or lost forever. The postal system is very bad in certain areas of China.
Main top Hub and bottom Base Cover:
While everything is apart and all electronics removed there are a few additions we need to make to the bottom cover plate.
1. Notice that the controller is just mounted in place with no real vibration protection. A good inexpensive addition to add is the M3x8 vibration dampeners sold by Quadframes.us link here… http://www.quadframe.us/collections/...ation-dampener
2. You should completely copper foil the bottom inside of your base cover and around the esc power cable before reinstalling the FC. Make sure once foil installed that you use a knife to open and clear all vent holes.
3. You should also completely copper foil the top inside hub cover again making sure all vent holes are clear when completed.
Why do we need to go to all this effort? Located directly on the back side of your base cover are your escs. They are emitting a lot of EMI/RFI in the process of operation and produce a lot of noise on FPV equipment and FC systems. Many people post GoPro videos showing Jello and blame it on the motors of a copter when in reality it’s the escs and wiring causing the affect. Since we do not want to obstruct airflow to the escs this is why we cover the inside of the base cover instead of between the escs and base cover bottom. In Part 2 of Tutorial 3 I show an X830 diagram illustrating all the different fields’ encompassing the copter.
Putting it All Together:
1. All screw to nut fittings are loctite but do not get on plastic parts.
2. All motors should match in the horizontal plane.
3. If you installed new motors they will not affect copter calibration.
4. If you installed any new escs they MUST be calibrated separately using the throttle port on Rx or loss of controllability will occur.
5. When doing first test of control systems DO NOT HAVE PROPELLERS INSTALLED.
6. When installing propellers make sure the blades are located on the correct motors, sequence 1-3 (1238) and 2-4 (1238R). Never use loctite to install props, you only need a thin nylon washer at most (optional) and 1/2 lbs of torque on the crown nut. I also use a tiny amount of silicone grease on the shaft and then wipe any excess off before installing prop. This keeps prop from becoming a permanent fixture to the shaft.
7. First real test flight is ON BENCH tied down allowing a little movement so you can verify each motor reaction.
8. Over the head testing is next, holding copter at ¼ throttle with both hands on copter. Test the response of copter when swaying copter left, right, forward and backward. Make sure copter reacts correctly before first live untethered test flight.
9. Keep copter in close, about 10 feet away, for the first few test flights at 3 ft off deck hovering. You are looking for any abnormalities in copter such as glitching, abnormal sounds or erratic movement. This is not the time to go off into the wild blue yonder.
Take it slow and build the trust between you and your copter as you both grow together.
From time to time review my many Tutorials whether you have the V1,V2 or Naza controller system you will still gain some insight from the read no matter which you own. Above all don’t be afraid to ask question on the X830 Thread. No question is dumb except the one you didn’t ask that might have brought you to this tutorial in the first place.
|Mar 02, 2013, 06:11 AM|
Thanks for all this. I have been looking for gps and autopilot information that is on the newbie level. A lot of the threads start like this, but after a few posts it goes into a technical Q&A session
|Mar 08, 2013, 10:31 PM|
Which Battery is best for your application?
This question seems to pop up every so often and I think my answer is always the same; it depends on the application you will be using it for. Nice generic answer huh? Ok today I am going to strive to answer this age old paradoxical question; do we start at the battery or do we start at the motor to arrive at our answer?
Which battery do I choose? What does 35C mean? How would that pertain to my battery selection? Why do I need to know the maximum amps my pack can handle? How do I determine this number? What is the 80% rule? Am I over discharging my battery? Why are my flight times not as advertised? These are just some of the questions we will answer in this tutorial.
Additional information on this subject can also be found in Tutorial 7 “Kv, Motor Designations, Kv vs. Torque and Kv vs. Propeller Choice.”
BATTERY / MOTOR
NOTE: For this tutorial I will be dealing with the X830 D series and mention the I and F series copters. Turbo Ace has not released the information on their motors since they were first introduced on the X830 Copter so I will be using the closes specifications I can find from LotusRC for this motor. See below;
Motor Dimensions in mm - 035x20, Stator Dimensions mm – 028x9, Shaft diameter mm 3.0, Weight 58g
Kv 650, Max output Pwr (W) 240, No load A/V - 0.5/11.1, Test pwr A/V - 1.8/10.5, Max current eff.(A) 15, based on 12 x 3.8 prop.
Batteries offered by WowHobbies;
MG Power Battery 2200mAh 3S 25C Lipo, use: X830 S/D models
MG Power Battery 5300mAh 3S 35C Lipo, use: X830 S/D models
GE Power Battery 5300mAh 3S 35-70C Lipo, use X830 S/D models
How do we go about picking the correct battery for our multicopter needs? To begin working toward a solution in our quest we must first know what the maximum continuous amp rating of our motor is. For the X830 we use 15Amps max continuous amperage to determine the answer. Here is the formula: 4 motors x 15amps = 60amps.
Next we need to decide what MAH battery size we need to maximize our flight time. MAH stands for milliamp hours or the total energy a battery can store at one time. The easiest way to explain MAH is consider it the Gas tank of your copter. The more MAH the battery has the more gas is in your tank. To determine how many MAH we can carry we need to know the base weight of the X830. Specifications say the empty weight is 1088grams without battery, camera mount or accessories but includes the Naza and GPS which weights in at 45grams.
In this example I will be using a 2 axis camera mount with servos 95grams and a GoPro HERO 2 99grams. This gives us a weight of 1282grams. In this case we wish to stay below 2200grams or 4.85lbs AOW. This leaves us with a battery max allowable weight of 918grams. We look for a battery with the most MAH to weight that would fit this criterion. We decide to use the 12000mahXL 840gram 3S Maxamp battery. http://www.maxamps.com/Lipo-12000XL-111-Pack.htm This gives us the largest gas tank for the weight allowed. Note: Never skimp on your battery packs always buy the best you can afford from a well known manufacture. It will pay you back dividends in the end.
This battery has a true 100C rating. What does the 100C rating stand for? The C rating stands for the maximum current (Amps) at which the battery can be discharged under load without damaging the battery. But how do we determine what the minimum C is for our D or I series X830 if we don’t want the maximum time aloft battery expense? This is very easy, we take our formula: 4 motors x 15amps = 60amps and add to that the extra amps drawn by our onboard FC and any other accessories we have connected to the battery in-flight.
When we look at the NAZA Manual we find; Power Consumption Max: 1.5W (0.3A@5V) with a normal of 0.6W (0.12A@5V). Ok that doesn’t sound to bad but if we go back to the top of the manual and started reading through we find if you are flying a copter larger than 650mm OR with heavy load you need to move to the WK-M FC. Down on page 37 of the manual you will also see under the versatile unit that the Red wire power wire output is 4A@5V. So under a heavy load I would think this FC with GPS and Compass can easily pull 3A. This would explain why many people have notice the drop in flight time compared to other FC systems. This 3A should be figured into the numbers above.
When we add the values up we find, 60Amps + 3amps = 63amps are being drawn with no additional accessories. Now IMHO let’s explains why the MG Power 2200mah 3S 25C battery should not be used on this copter. If we take 2200mah and convert to amps we get 2.2amps. Since the battery is available for the units per battery ad, we will do the math. 2.2A x 25C = 55A of available power but wait, we need 63 amps. For people who have been flying this battery with the Naza FC my calculations show that you are getting a maximum flight time of roughly 4.2 minutes while slowly killing the battery life. I highly recommend against using this battery on the X830 quadcopter.
What about the MG Power 5300mah 3S 35C and 35C-70C battery? Use the same math, 5300mah is = to 5.3A x 35C = 185.5A + 3A = 188.5A. This fits within our mathematical guidelines so this battery is good to go with a flight time of roughly 8-10 minutes. We could increase this flight time if we increase the blade size, such as going to the CF 13” props. This would improve our flight time to roughly 11-13 minutes depending here again on maneuvering and density altitude. By the way before you ask the 35C-70C version is just a short heavy burst type battery but normally works at 35C.
What would happen to our flight times if we did go to the 12000mahXL 3S flight pack mentioned earlier? Well this would move us up into the true 30 -35 minute flight time realm! This again would work well with the D and I and converted to single battery F version copters.
What would change these flight time calculations? If you are doing lots of high speed flying with changing directions and climbs you will eat a lot more power and decrease your flight times. If you add lots of extras on board equipment, weight and use the main battery to power them this would also decrease your flight time. If you wish to increase your overall flight times use slow and easy maneuvers with lots of hover time and always think of ways to lighten the load.
The 80% Rule
The 80% rule came about for a reason, not only to protect the battery but also the multicopter. With the X830 copter while the Lipo is under a load the voltage is fairly flat during hard discharge UNTIL you reach about 10% of the remaining capacity of the pack. Once you hit this magic number capacity drops off rather sharply also at the same time your copter starts a descending controlled crash unless you can land quickly. Thus the 80% rule was brought about so you had time to land before damaging the battery and or have to make a controlled crash off field. But how do we calculate this 80%?
Let’s use our 5300mAh 3S 35C pack as an example: 5300mAh X .8 = 4240mAh. This means you can draw down the pack to a maximum of 4240mAh during your flight. Ok, so how do we measure after a flight how many mah we used? First you need a smart charger, one that displays the total mah put into the battery during the charge. Once you have completed charging the number shown represents the amount of mah you put into the battery, in our example case we will use 3900mAh. The formula would be mah inputted / total pack mah x 100 = % or 3900mAh/5300mAh = .7358 x 100 = 73.58%. This leaves us well above the 80% rule and a safely discharged pack.
Flight time by the clock
Ok so now we know how to determine the mah’s we have used during a flight let’s determine how to guess when its time to land based on flight time. The easiest way to accomplish this is with a stopwatch or cooking timer. If you are like me I just don’t seem to hear my beeper go off on the Transmitter if there is a lot of noise in the area. We are going to start by using a 5300mah battery for this example.
First fly the copter for 3 minutes and land. Recharge your battery and see how many mah you used on this flight. Make sure on the flight that you fly it naturally as you normally would. The next flight we are going to double that time to 6 minutes, land and recharge the battery. What is your reading now? Have you reach the 50% point? If you are still in the 50-60% used mah then take it up for 9 minutes and recharge. Do this until you are at the 75-80% value. This is now your real flight time per pack.
Another way I personally accomplish this 80% rule is by using a buzzer alarm on the balance side of the battery set to 3.7volts. This way when it alarms I land and examine the meter. Normally it reads around 3.8volts without a load. I know this setting looses a little flight time but to me it’s worth the savings in battery cost and possible pack failure due to over discharging in-flight.
Personal Observations and Recommendations D series X830:
Wow Hobbies advertises on the D series X830 that it can take 3 different battery setups;
• Standard Battery: LiPo 3S (11.1v) 2200mAh 20C Flight time 6-8 min 160gr
• Extended Battery: LiPo 3S (11.1V) 5300mAh 45C Flight time 15-18 min 380gr
• 2 Extended Batteries in Parallel: 2x LiPo 3S (11.1V) 5300mAh 45C Flight time 23-30 min 760gr
With the additional comments;
• Weight without Battery & Camera Mount: 1088g
• Maximum Load (Standard): 1P 3290g
• Maximum Payload: 2358g = 5.2 lbs. For proper operation and stability please limit the payload to about 2 lbs.
My flight times are based on the standard 12 x 3.8 propellers.
Unfortunately these numbers are not realistic flight numbers as shown with a standard D series X830 with 12" propellers. I have tested X830 copters (own 3) with many battery / weight combinations to maximize flight time with above offered batteries and the numbers do not hold up during testing.
What can you really expect from these batteries based on maximum AOW of 2358grams? If we used the 2200mAh battery flight time would be 3 minutes maximum. Again I highly recommend against using this battery as shown in math earlier in tutorial.
If we used the 5300mAh 45C battery flight time would be 7 minutes before we must land. This is about half the time shown above. The reason for the difference seems to be the calculations were computed on a stripped frame copter with no battery load which would give us 15 minutes of flight time. How close can we get to the numbers above with a battery included? Doing the math we get 1088grams + 380grams = 1468grams which well give us a flight time of 11minutes.
With 2 flight packs added to frame we can do the math. 1088grams + 760grams = 1848grams which gives us a flight time of 19 minutes. Well again if we go by just frame only we get 31 minutes. So finally this explains why people are not getting the flight time they expected from reading the advertisement.
But there is another variable involved not taken into consideration which would let Wow Hobbies off the hook for flight times. IF you did the same calculations with the new CF 13”x5.5” propellers this would be like subtracting 400grams of weight from your copter. That is a big difference and as we have seen in the math if we are working with frame weight only we can hit most of the claims using the 5300mAh battery, why? Because it just so happens the CF blades give you the same performance as if you had no battery pack. This of course is only with the one pack flight time.
Now that you see how easy it is to calculate the flight times above you can try it yourself with the I and F series. Better yet take your own X830 quadcopter weight then take 3290grams and find your % of total weight. Example; 3290 x 33%= 1085.7 which is close enough to 1088grams which is empty weight of frame. Now go to the Lipo battery calculator site and plug in your copter motor 4, max amps 15, max draw of equipment 3A, battery 11.1, battery pack size in mAh and finally our 33% for flight load on slide right side. This will give you the total flight time and the 80% rule flight time based on your inputted information.
With this information you should be able to go out on the market find compatible batteries to maximize your own flight times. Key is buy good batteries with calculated C value needed and to save every gram of weight you can on your copter for maximum performance and flight time.
Battery calculator site;
I hope you have enjoyed this tutorial and don’t forget to check out tutorial 7 for additional information on this subject.
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