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Discussion in 'General Discussion' started by ChrisMohrSr, Oct 7, 2013.
If I take off too slowly my Phantom has a tendency to tip forward a bit. Why is that?
Your props are out of balance. I had some carbon fiber props and it was happening to me. In fact I was getting some erratic behavior from my Phantom. I switched to some stock props and it is smooth flying.
Or your Phantom is merely front-heavy (with a gimbal?), doubt it's the props, as the motors will compensate for prop differences.
if it flies normal once it's in the air you're ok, otherwise run advanced calibration to help keep the gyro's in check.
sometimes it seems like mine wants to tip forward, so I just take off pulling my right stick back a little bit,
I've got balanced props and mine does the same. I like the nice clean slow take off but its not possible so I take off fast. Its an easy fix. and free.
Mine takes off and lands as slow and as gently as I want it to. I can hold a hover about 5-6 inches off the ground if I want.
"ChrisMohrSr"]If I take off too slowly my Phantom has a tendency to tip forward a bit. Why is that?
Take off in Atti mode & give it heaps, if you have the centered throttle, max it out then let the stick go once off the ground, flick to gps mode. Works for me
Another tip on this is to make sure you leave the Phantom on a flay, level surfice while the IMU warms up.... if it is on unevenground I have had it tilt before. Also don't fiddle with it during this time. If you move it too much it will through it out a bit. I didn't think much of this to begin with but after a few impatient fiddles with battery cable and camera I've seen adverse effects (not major, just noticeable).
My assumption has been this: I have been surprised by the fact that there seems to be very little very little attention paid to keeping the additional payloads in the Center of Gravity. The Phantom design takes liberties with COG that fixed wing birds wouldn't think of. I am primarily talking gimbals and cameras here. They are hung under the front of the bird....to eliminate landing gear in the FOV of the camera.....throwing off the COG. The fact that it works at all, I assume, is that the various balancing mechanisms, reading the levelers, compasses, accelerometers, etc. correct for the inevitable tilt and adjust rotor power to achieve level.
BUT, preparing to takeoff from a level base...the bird has NO WAY of knowing what the weight distribution is, and how to adjust various motor powers to balance UNTIL it actually lifts off. If the COG is to the front, it initially powers all motors equally...the bird starts to lift....then lists to the heavy side...inevitable starts to side that direction...then the balancing mechanisms take over and it flattens. Actually, the exact same argument can be made about propeller balance, although prop weight balance does not translate as directly into reduced or increased lift, but LIFT balance between props is another unknown UNTIL the bird actually loses contact with the ground and begins to tilt...and inevitably slide...then corrects.
My bird slides forward on liftoff most/all of the time and m assumption has been because of the Off-center COG. I could be completely wrong in my analysis but this I what makes sense to me.
I moved COG +1 cm on X axis with Gimbal + Gopro3 + CCD FPV camera on front. Just climbs straigth up
"I moved COG -1 on X axis with Gimbal".
This probably qualifies as a stupid question....as I only recently got the computer controller program working and have not actually adjusted anything yet....but I assume that you "moved COG -1 on X axis with Gimbal" in the computer setting....so the bird's onboard controller is aware of and corrects for the front loaded COG from the very start??
Deleted... double post
Those who never posted their "stupid questions" now are crying because their phantoms flew away or crashed. I did mine when I began with quads. I prefer to be a stupid questioner than a smart crashed pilot. :lol:
Yeap, when you change COG values the FC "assumes" new values requires more or less correction on 1 or more motors / rotation etc. for keep it hovering and avoid events as tipping. Not related to GPS corrections just for horizontal / vertical alignment while flying.. Hey I posted a mistake. My value in X axis was +1 not -1. Really the COG havee to move forward because heavier stuff moved in front of phantom
I want to agree with that reasoning, but the NAZA manual and wiki are very clear that if the CG is *forward* of the GPS module, the value entered for X must be negative. (In the manual illustration, the green lines are negative values.) In other words, it represents how far the GPS is behind the CG. Positive value if the GPS is in front of the CG, negative value if it is behind the CG.
If you don't mind a test, it would be helpful to see what happens if you replace your +1 with -1 and see if it makes a difference.
Try new landing skids; they can help you move your center of gravity.
54! And fold?
http://www.helipal.com/carbon-fiber-fol ... s5hlcdeff4
I have tried a few variations on skids. They were not all that great. They may be a bit heavy but I do like my new skids. They are night and day.
wow, anyone else have anything to say about these. I might buy them.
It looks like there are a few versions now. This was not the case when I ordered last month:
I almost forgot, the rear section is a battery tray and clamped on with two Tarot gimbal mounts. The side mounts for the FPV transmitter and GPS tracker (or whatever) are removable. There are ways to trim down the weight on this thing and it is easy to mod. The Carbon tubes could be cut down etc. I would say that one could probably knock off 100 grams and it would not take a lot of creativity.
My Phantom came in a little hard today and the carbon fiber landing skids absorbed all of the shock. It would have been hard enough to scratch up the stock skids.
1 month old Phantom flew nicely out of the box. Thought I could increase performance by upgrading to carbon fiber blades purchased from Amazon. Maybe not. Did have a fly away on the first flight with new blades but determined that it was caused by interference from the WiFi on the GoPro Hero 3+ and failsafe got it back safely. Can any of you experts help me determine if this erratic bahavior is caused by propellers or something else?
http://www.youtube.com/watch?v=cohzBORT ... load_owner
Carbon Fiber blades are much stiffer than the stock blades. The aircraft is going to be more sensitive in handling. Whereas the stock blades have some flex in them, that absorbs some of the bumps, the CF blades do not.
Also, when you were flying in GPS mode-was there any wind? The aircraft will tend to compensate to try and hold position by increasing/decreasing the speed of 1 or more engines. This is especially apparent during windy conditions.
Last; be very careful when landing with CF blades. If you tip over, they are likely to shatter. IMHO, since you are new-you should go back to the stock/plastic blades and fly those for awhile.
I don't see anything unusual in your video......