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Mar 12, 2013, 10:41 PM
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Discussion

H-quad vs. Spider quad


I am planning on building another fpv quad, this one to take hiking with me. Im between an H-Frame and a Spider frame design. The H frame looks simpler, but the spider quad definately looks cooler, and a little more stable/maneuverable.

My question is, whats the main difference?
Are there any benifits of one over the other? Both keep the props out of view and both provide a large space to mount gear.

Whats the main advantages of either?

Thanks guys
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Mar 12, 2013, 11:05 PM
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SeismicCWave's Avatar
X quad, H quad, spider quad what ever quad configurations you can imagine still uses 4 motors and 4 propellers. No matter which way you go your CG still has to be in the middle of the 4 propellers. So any added stability is all in your mind.
Mar 12, 2013, 11:27 PM
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Interesting. Makes sense.

But I heard that having the sweep of the arms, such as a spider quad and Not an h quad, allows diagonal roll stability. For example, I heard that h quads are susceptible to a sort of oscillation diagonally, such as from front left motor to back right motor

So supposedly the sweep of arms on spider quads eliminates this

Just what I heard
Mar 12, 2013, 11:29 PM
aka Helidaho
AeroVideoUS's Avatar
With that being said...

There are definitely differences as an H quad has its main payload stretched the length of the frame so usually it takes more inertia to move the pitch and way less to move the roll. That's been my newbie experience with PID tuning anyway. So for example I have the pitch gains higher than the roll gains on an H-Quad.

Then you get into the frames where the motors aren't equal distances apart (length vs width) and I think those are harder to tune.

I'm no physics major so it may all be in my head but I think primary decisions are on component replacement/availability as well as how well does it accommodate what you want to carry. Of course how cool does it look

Paul
Mar 12, 2013, 11:56 PM
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Quote:
Originally Posted by AeroVideoUS
With that being said...

There are definitely differences as an H quad has its main payload stretched the length of the frame so usually it takes more inertia to move the pitch and way less to move the roll. That's been my newbie experience with PID tuning anyway. So for example I have the pitch gains higher than the roll gains on an H-Quad.

Then you get into the frames where the motors aren't equal distances apart (length vs width) and I think those are harder to tune.

I'm no physics major so it may all be in my head but I think primary decisions are on component replacement/availability as well as how well does it accommodate what you want to carry. Of course how cool does it look

Paul
Okay that makes since as well. Thanks for your input (:
Mar 13, 2013, 01:19 AM
AMA 46133
SeismicCWave's Avatar
Quote:
Originally Posted by corsair2014
Interesting. Makes sense.

But I heard that having the sweep of the arms, such as a spider quad and Not an h quad, allows diagonal roll stability. For example, I heard that h quads are susceptible to a sort of oscillation diagonally, such as from front left motor to back right motor

So supposedly the sweep of arms on spider quads eliminates this

Just what I heard
What you are saying will be the difference in the frame construction. That has nothing to do with the aerodynamics of the machine. Of course the difference in the frame stiffness will determine how well the multi rotor will fly but that has nothing to do with the way the propellers are configured.
Jul 05, 2014, 06:53 PM
Multirotor Enthusiast
Aren't most spider Multis 6 motored?
Jul 05, 2014, 08:34 PM
Team AlienWarpSquad
The spiders in my yard have 8 legs not 6.
Jul 05, 2014, 10:07 PM
Registered User
Spider quads are actually one of the least stable frame there is. The non-symmetrical distribution of the motor means the center of thrust does not line up with the center of gravity. And that makes for some rather unstable flight characteristics.

Quote:
Originally Posted by SteveNunez
Aren't most spider Multis 6 motored?
Actually, the most common spider frames are quads. SK450 Deadcat, Reptile, and the TBS Discovery frame are all spider based.






One interesting spider quad which i would say is stable is the RCTimer Spider. The thing has the balance and motor layout of a standard 450 X-Quad.



And comparing it to the SK450 deadcat which is probably the *least* stable quad ever made.



BTW, i still fly the deadcat. The KK2 is easy to configure so you can tune the power distribution on the different axes specifically for the deadcats layout. And even with the camera far back for crash protection you still can't see the blades. I certainly don't do acrobatics on it tho, the dissimilar power distribution can make for some rather hairy situations if you stress the motors.
Last edited by Hajile; Jul 05, 2014 at 10:17 PM.
Aug 11, 2014, 11:55 AM
Registered User
So would you say that an H-Quad is more stable.

I am looking for good steady/hold position flights with little moving around.
Apr 11, 2015, 07:02 PM
aka Gains
Quote:
Originally Posted by flyandi
So would you say that an H-Quad is more stable.

I am looking for good steady/hold position flights with little moving around.
Tilting the motor's slightly to the center of the quad will also increase stability (feeling like it want's to self level) while reducing efficiency but if you're looking for something more stable why not try a hex? blackout's spider hex is incredible to fly and the bigger 600+ are inherently more stable again.
Jun 02, 2015, 02:13 PM
Registered User
The Center of Thrust diagram is completely wrong.

Assuming right/left thrust symmetry (which we have here), the COT falls on the horizontal green line at a point which is the same distance from the vertical black line on the right, and the vertical black line on the left, which appears to fall ~exactly on the diagram's COG mark.

In other words, COT is halfway between the front thrust and back thrust.

engineer/4.0 physics student.
Sep 24, 2015, 06:50 PM
Drprop
DRPROP's Avatar
The mini H quad is mint for agility and tight handling, but the spiderhex with 6 motors will need more space to play around in ( its got alot of power on a light and nimble carbon fiber frame

i tripped over this while searching for Blackout content and reblogged it
http://www.icktrading.com/blogs/fpv-...e-midair-crash
Last edited by DRPROP; Oct 06, 2015 at 11:18 PM.
Dec 20, 2015, 08:28 PM
Registered User
Hi there,

I am looking for building a spider frame (quad).
Does anyone can help me with some of the technical questions?

- how much I should move the center of gravity?
- any consideration on the angle between motors?
- any considerable improvement on slightly bend the frame on front/back axis (to simulate a dihedral)

best regards,
Marcelo


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