A Yolo Wizard posted:

Theres no way thats going to be cheaper than the hking one with good shipping (I got a pair super quick at $36 w/ my platinum account)

n.. posted:

i tried. ordered it a month ago. usps hosed up and accidentally returned it (?). wasted half a day in line at the post office because they send poo poo w/ signature required (why? they've never given a straight answer on that). finally get up to the window and "uhh, it's not here.. looks like it got put int he wrong spot and sent back."

i'm done with hobby king, the extra $15 is more than worth my time and sanity.

bring back old gbs posted:

Also, they do the annoying "legitimate" business thing and list the EXACT cost of the items and detail that it has lipos, etc. So you're paying extra fees to pick stuff up as well. It's shady as poo poo but I like that other less reputable places will just say "hobby parts, $5.00" and bypass all that.

dreesemonkey posted:

What does everyone thing about some of the toy-grade quads? My friend showed me his Syma X8C over the weekend and it seemed really cool as an "intro to quads", especially for ~$80. Flight time was good even when pulling his gopro around.

Obviously you guys seem to be into rolling your own, but are the toy grade ones a good place to start?

Combat Pretzel posted:

Is sealing up a 250 quad, to reduce wind turbulences, worth the additional weight of the plastic?

bring back old gbs posted:

Yeah Symas are fine to get your feet wet. $80 is a lot for a toy grade though unless it's one of those FPV Hubsan ones

Hubsan x4 and Blade Nano QX get recommended often but neither of those will come close to lifting a gopro

MrYenko posted:

Probably not, unless you're racing at 60mph+ on the regular.

bring back old gbs posted:

The biggest issue for quad aerodynamics seems to be that they can fly in any direction. With planes and boats there are body lines that give away direction of travel because the aero/hydrodynamics? are built into their basic function. How do you do that to a quad that can go full throttle and instantly change directions?

Nerobro posted:

I'm not even sure that's true. I'd like to see some testing.. but those flat arms out in the wind are really awful for aerodynamics.

Combat Pretzel posted:

Is sealing up a 250 quad, to reduce wind turbulences, worth the additional weight of the plastic?

MrYenko posted:

They certainly are, but any effort at cleaning up a quad that I've ever seen has dramatically increased not only the cross sectional area as it applies to forward flight, but also the area of structure under the rotors. My gut feeling is that at the low speeds that quads generally operate at, you'd be better served trying to minimize structural size and mass, rather than attempting to improve the C/D.

Nerobro posted:

I've got ideas for taking care of that. I've outlined them earlier in the thread. There are "unstallable" airfoils, that still provide the drag reduction of an airfoil. Heck, just some standoffs to raise the prop disk, and a "nose fairing" would more than halve the drag of the arms. It's fairly easy to design a fairing that's aerodynamic in at least two directions.. the two that matter for a quad are forward, and "up". The warpquads with the vertical stack of battery, flight controller, camera.. are going the right direction with that.

ImplicitAssembler posted:

That's fine, but you need all 3 dimensions for a racequad. The biggest factors are props and weight with CG trailing at a distant third. Aerodynamic efficiency on something where 90% of the surface presented to the airflow is the props is largely relevant, more so when it comes at the cost of weight & strength.

This is still worth reposting, though: http://fpvlab.com/forums/showthread.php?37954-World-speed-record-with-250mm-(or-under)-size-quad
This is made for straightline speed only, but it's still interesting.

Nerobro posted:

Imagine getting a free 20% more thrust. That's what you're going to get with good aerodynamics on the arms. You can trade that for smaller props to make the thing more agile.

Making the fuselage .. wing-ish.. would give you more more thrust to throw at corners without needing more horsepower.

... I'm going to need to break out the math on this, aren't I?

Bad Munki posted:

ImplicitAssembler posted:

Sure, break out the math. Better yet, build one and prove it.
You may be able to get 20% more thrust in some situations, but it will come at a cost in others and most definitely will come at the cost of more weight and less durability.
Again, look at the fpvlab thread and see how much trouble he has getting it to work for a quad flying in a straight line.

Nerobro posted:

I've got some testing equipment .. I can do that. I "should" do that. I'm not talking 20% more thrust in "some" situations, i'm talking 20% in ALL situations. If you're getting 20% more thrust, you can afford some weight. Arm fairings don't need to have any effect on durability. An aerodynamic fuselage definitely leads to "more things to break"

I have checked that FPVlab thread. I like it a lot. He's doing a lot of things right.

Nerobro posted:

Imagine getting a free 20% more thrust. That's what you're going to get with good aerodynamics on the arms. You can trade that for smaller props to make the thing more agile.

n.. posted:

Well I'll be damned, by some miracle usps pulled through and delivered my teensy cam/vtx from HK.



This is hilariously fun. Need to figure what the best motors i can use with the beef's brushed board are for maximum oomph, because it flies weak af like this.

dreesemonkey posted:

What does everyone thing about some of the toy-grade quads? My friend showed me his Syma X8C over the weekend and it seemed really cool as an "intro to quads", especially for ~$80. Flight time was good even when pulling his gopro around.

Obviously you guys seem to be into rolling your own, but are the toy grade ones a good place to start?

ImplicitAssembler posted:

Well, you could probably become pretty rich if you can come up with a practical design that offers 20% more thrust.
You have access to a a wind tunnel? Aerodynamics software?

mashed_penguin posted:

I don't think that current race quads are lacking top speed, maneuverability or power to an extent that aerodynamics would really add much. Most races seem to be lost at the moment through attrition in that most pilots are crashing out and not finishing or not posting the best times before they wipe out.

Maybe one day people will get so good at flying the the things that a little bit more straightline speed matters or endurance formats will become a thing and aerodynamics might make a difference. But at the moment everyone is flying grossly overpowered carbon bricks on short racetracks for a few mins at a time. I don't see fancy cowlings etc trumping durability any time soon.

Combat Pretzel posted:

Do you think something like this to wrap around the arms would help something thrust-wise?



--edit: Or would the peaks need to be angles forward (and backward respectively) to deal with wind facing the drone during flight?

Nerobro posted:

Cheap wind tunnels come in the form of the tops of cars. If I need to simulate the drag/thrust on a airframe strapping it to a car and giving it a go is a fair shot.

Nerobro posted:

For example, if in free air, you're making 600g of thrust on a 5x4. That means you've got 18 square inches of swept area. (excluding the motor area in the middle) On a ZMR250, that arm is eating two square inches of your swept area. That works out to something like 70g of lost thrust due to prop-wash blocking. "any" kind of fairing would get you 52g back. Or 200 some grams for the airframe as a whole.

ImplicitAssembler posted:

And just how will you measure the drag?

quote:

..and you're going to do this for all attitudes?

quote:

Except that you still have the low pressure that the prop creates in front, a gap behind the prop and the arm,etc, so s straight calculation of Cd wont work.

Nerobro posted:

That's kinda the idea, and that's better than a flat arm. But if you're doing something like that, you might do an actual airfoil and do even better. Below a 3:1 aspect ratio, airfoils really don't stall. If you did a teardrop shape, with the tail going towards the rear of the quad, in addition to getting less drag from the flat arm, you'd also pick up some forward thrust.

Combat Pretzel posted:

Kinda like this then? I guess I could fillet the edge to make it teardrop-ish.



I still need to make the counterpart. The other one was symmetrical and less work. There's only so much airfoil you can emulate before things get way too big. The edge has already only distance 3-4mm to the prop.

sigseven posted: