This was the first fly of my baby, it was my first build, I like it because it's very strong and allows me to learn without crash damages, and a great code that support all design errors, but now I'm on a second stage, I learn somethings and now I want a more efficient cuad.
a) 20 min flying time at least (today 14 min)
b) More stability in windy days.
c) reach 1km min with r modem.
d) Resolve mag field limit.
e) Mantain the portability (no much bigger)
f) Beauty is important for me too ;)
I started this work last year (2014),
First I ligthweight as much as possible, only cup -90 grs, take away an extra floor, etc, total -200grs and reduce vibrations but I have many work to do yet and I think that a post it's the best place to share with you and recive your help, any idea is welcome.
First thing that I'm going to do to continue is to change motors, it has Turnigy 2836 950kv they are old cheap plane motors with bearings near limit with 10.47 CF props and 30A esc, I test them with my ligthest batteries two Multistar 5200 and gives 26 A consumption
Ship weights now 1.47kgs without batteries, with FPV and Dragon receiver and this is the photo
My first attempt to optimize, the result was a complete new cuad, the Tarot that flies 25 min, this my second one.
I had exactly this issue with some 14" props on My Flip FPV Pro.
I had clearance, but only about 1/8".
It simply wasn't enough, they do not hit, but the prop wash streams are so close together that they definitely interfere with each other and produce unusually high turbulence and vibrations in anything other than a perfect hover.
Quiet and good in a straight hover but very noisy under increased throttle or at compensating for a descent and very visible on the video recordings as well.
OK in hover, a mess under throttle.
Switched to 13" T-motor props and the problem disappeared, smooth at all speeds.
From my experience, I think you need a minimum of a half inch prop tip clearance and an inch is better.
I have some APC props and they seem to be OK if a bit flexible, but I am very happy with my T-Motor 13" carbon fiber ones (they are not cheap though).
Thank's for your answer Gary, for anxious I bougth this ones but I'm going to spend more time and wait for 13 ones, what is your flying time with 13 props and ship weight?, another possibility is to enlagre the arms but for five item (mantain the portability) perhaps better the 13 props choice.
While I continue searching the 13 props (perhaps I can have CF ones) I 'm doing some test with this ones, I assemble the four motors and get a surprise :O , looks photos, my cuad isn't simetric
I fly a little in th late afternoon and fly, consumption didn't looks much efficient but a very little test.
I guess if you really don't like the 14" props there would be nothing to lose to cut 1/2" off the ends of them. I have used a pair of scissors first then sandpaper to round off then of course balance them. My first quad I made out of 1/2 square wood for the arms and thin ply for the center. very light. I got just over 20 minutes. This last quad is almost the same design but uses aluminum are and a bit more plywood for the center. Not much weight difference and yet now I only get 13 min. If I had to take an educated guess I'd say weight is %85 of the equation on flight times the rest like motors and prop size can only help a little.
Haven't I read going with a 4s battery and those larger diameter motors is best??
Thanks for posting I might end up doing the same thing after you spend all the time figuring it out. lol
Thank's Richard for the tip, I wasn`t shure if that possible you confirm it is, I'm going to do more test to evaluate them better, i notice that flies under 50% trottle, that indicate me that, or props are little big or I can carry more weight? for example the camera with gimbal or more batteries to fly more time? Sorry the silly question, how I know that motor is not over demanded? for heat?
No question is silly!
I guess I'd say if you could get a copter to hover at below 1/2 throttle maybe even 1/3 your doing pretty good. That landing gear you have there is kinda heavy. My son had some like that. very nice the way they bend but don't break! But they are heavy. Anything you can do to lighten it up is good. Shorten wires where you can. Every little bit adds up to a longer flight time.
ps I would not try and shorten carbon fiber props. That could weaken them and perhaps they would then fail. Just wanted to clarify that. But the plastic ones no problem.
Agreed on shortening CF props, its not worth the hassle.. Unless you really want to deal with cutting them, sanding them, balancing and sealing them back up with epoxy (and balance again), its just easier to get the proper sized propellers...
Also on shortening the wires, long wires make more interference, so twisting and making them as short as needed (not too short, that you cannot work with them) help as well..
If you can hover at under 50% throttle, and motors/escs are cool, then things are going well for you. Less prop size, or flatter pitch can help...
Thank's for your answers, wires I have a lot to shorten, antenna included I'm not cut yet because I'm not shure if I have to enlarge the arms, change them, or change the hole frame but motors wires are prety large, I'm going to weight the legs, thank's for the advertise, when I recive the compass, thank's to Richard helps, APM moves down and all that tall and heavy floor disapears too, parallels perhaps are unnsesary large too, batteries I'm going to try to attach directly to EP as Forrest recommend
I'm sorry I didn't notice that earlier too, I had noticed something off about them, but thought it was just an illusion based on the different colors of your arm.
Now, blowing up your picture and using a ruler I get 3" of clear space from the edge of the black booms to the edge of the center plate and 2 1/2" on the gold arms for the same distances.
Of course those aren't actual measures since there is no way to judge actual quad size comparatively.
But the ratio is correct (and it won't work!)
You might be able to get it to fly, but no amount of tuning can actually fix that kind of assymmetry.
If the front and back prop tip clearances / distances are the same and the side to side are also (even though different than front to back, you can tune out the asymmetry by separating the roll and pitch control PIDs.
I do that on my H style copters all the time.
But that isn't what you have and it produces an asymmetry insoluble by our PIDS you would actually need to separate out each motor and we don't have that.
In your case, if possible, I would just make the gold arm lengths the same as the black ones with the same motor mount to center plate clearance, then you can even use the bigger props without problem and yes the 14" props will generally give 10 to 20% higher efficiency than equivalent 13" ones.
You really need to fix this in any case, you could also shorten the black arms to the same as the gold, but then you would need to use 13" props.
You should also put your GPS on a mast on the center hub too, because the way it is prop thrust will be asymmetrically interfered with by it.
And if you use carbon fiber or carbon filled props they will interfere with the GPS.