H vs X Frame - RC Groups
View Poll Results: Which frame is more suited for FPV racing?
H Frame 32 25.00%
X Frame 86 67.19%
Other 10 7.81%
Voters: 128. You may not vote on this poll

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Mar 17, 2016, 02:42 AM
What can possibly go wrong?
Poll

H vs X Frame


As the sport of FPV Quadcopter Racing becomes more main stream, the opportunities for career and profit will follow. Sponsorships, racing league winnings, small businesses, etc.

Alongside racing, freestyle stunt routines will also have similar opportunities. Though as we are seeing, racing seems to be gathering more public attention, and thus higher potential earnings for the pilots. So for the sake of simplicity, I'd like this thread to only pertain to racing.

I understand races on the professional level will most often be held on specific, identical quads built by the company hosting the event. So even if there is a notable advantage to flying an H over an X or vise versa, in the end it may not matter.

Though for the sake of knowledge and discussion it can only benefit us to discuss and further understand how these two frames compare in flight tendencies in the paramiters of racing.
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Mar 17, 2016, 10:06 AM
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NutBag's Avatar
It's all regurgitated, they'll tell us anything to sell their wares to the ever wanting addicts.

3 year old blackout mini H frame and an Alien, the worlds most popular X frame... But the Alien has purple bits...whaaaa

I think pure Xs like the Kreiger fly nice, they suck for mounting GoPros etc though.
Last edited by NutBag; Mar 17, 2016 at 10:12 AM. Reason: Pic
Mar 17, 2016, 01:08 PM
Registered User
An X frame with a long body that is the same size as an H will fly exactly the same.

Where an X frame makes sense is using small components and getting rid of all that wasted space.
Mar 17, 2016, 04:46 PM
Registered User
I have flown two designs so far that we are working on. One is similar to a H frame and the other is a true X frame.

I have to say the X frame with the same rates etc flips and roles faster. Don't get me wrong the H frame flies great but I think there is something to be said about the X frames. With regards to rates etc just add more to the H frame quad and you have for the most part the same feeling of an X frame for racing.

The X frame we have designed is not like any of the frames out there. I see a lot of talk about frontal area and removing it from the frame, that's great but then to only stick a battery under the frame that adds a lot of this frontal area back into the equation, does not make any sense. We have used this battery area to allow for easier equipment installation, if your going to have the frontal area of the battery why not make it useful right.

Why do we want to put the battery on the bottom of the frame? I have tested bottom mounted top mounted and center mounted and I can say I like center mount the most and top mounted right behind the center mounted configuration. By center mounted I mean center the props to the battery looking at it from the side. The way I fly and land I don't think a bottom mounted battery would last long anyway, maybe in the grass, but I run a lot in parking lots here.

I think for racing though a well tuned X frame or H frame can win on any day with equal pilots flying them.

Bill

For free style something I suck at maybe an X frame would do better I am not sure.
Mar 18, 2016, 01:41 AM
What can possibly go wrong?
Seeing as the poll clearly shows pilots preference for X frames, I wonder why every large racing league uses H frames. Surely the builders are experienced in the sport, and thus (according to the statistics provided by this poll so far) are likely to also see the advantages of X frames.

It must be some technical or monitory limitation then?
Mar 18, 2016, 11:48 AM
Registered User
Large leagues like DRL and Dubai? They both needed to run heavy HD equipment so I think they were forced in the H direction for now.
Mar 18, 2016, 04:30 PM
Registered User
X is better for pure racing. It simply has a smaller aerodynamic frontal area and uses less material. But there is no room for additional equipment beyond the bare essentials.

There are several x frames with fpv capability that are in the works. I imagine within the next few months there is going to be a major shift to X. More than we have already seen. There are more specialty products which make smaller builds easier. Things like integrated flight controllers and PDB, integrated flight controller and VTX etc. As more products like those come about we will have less need for H frames.
Jul 26, 2016, 12:06 AM
Registered User
I'm interested in reviving the thread but mainly to address the differences in flying techniques. Flying an X is much different. They look like gnats in the air. Anyways...

1. With the much lower frontal aerodynamics the X seems to fly faster with much less throttle. My TheoryX, at 60 percent throttle, will go as fast as my Vortex at full throttle. There is a difference in motors, but I need to add that the batteries seem to last just as long if not longer. It doesn't mean much without metrics. But we haven't had the opportunity to stop watch and log battery results.

2. With much less frontal area, 45 camera tilt is also a different animal. You might have had 45 on your H, but you were pushing air, and it was being deflected down. Somewhat like a spoiler, so unknown to you you were either pulling back more or adding throttle. Not so with the X. It has different aerodynamic issues but it seems more idelic. The motors seem much less hindered and acceleration seems much much faster.

3. The part I hate. Where the camera is located. Landing an X is a pain. Best way is to come in quickly and low, and 180 and back it down quickly. Unless your landing on asphalt. Because the landing gear on an X is the battery LOL. Having the camera high causes me 2 issues. It's still the same old yaw and aileron roll but now you get a high centered camera movement. On many H the camera is the lowest part of the rig. If you can see individual blades of grass you've got it just right. On an X, if you see individual blades of grass you're likely to see a whole lot more because you'll be looking out of the grass.

4. The X does seem much more damage resistant. It's lighter. There is elasticity from the blades for much of the unit. During an impact the battery is at the rear, so the front of the frame takes the hit. The antenna is still the thing that gets the ragging. HH said put a stubby on the ThryX I guess they forgot what happens when you hide a TX antenna between Carbon. The whole thing is lighter so during an impulse there is less inertia, and therefore less kinetic energy. I have not broken a blade yet. Bent yes, broke no. The frame I have is thinner, but with less weight it truthfully appears to be elastic during the impact.

5. The slalom. Much harder. Much more Yaw movement. Very little time to look at the obstacles during high speed maneuvering. With the high centered camera and high camera angles you are seriously advancing your turn entries. Start your turns a whole lot earlier, and your braking because there is less body to use as a brake or airfoil.

These are just a few things I've been contemplating as I go from ZMR that was maxed out and a vortex because the vortex ended up being a good value, to the X frame. That ZMR was way faster than the Vtex but I was always tinkering with it
Jul 26, 2016, 01:21 AM
Registered User
Wrecking Ball's Avatar
Well, you cant really compare H to X unless they have exactly the same components, tune and weight.

I have both X and H frames with completely different components, but to be honest I dont see the difference. They appear to fly differently because of the weight, cg location (on longitudinal, lateral and vertical axis), and for the most part your tune and quality of your FC/escs/motors and props of course! The lighter the frame the more nimble it is, the less inertia you need to fight during turns thus you will have faster laps. However it will be the least stable one.

Drag... the quadcopter itself is not the most aerodynamic aircraft for sure. 4 props at 70 angle at full throttle create huge amount of drag, so reducing the frontal area will of course help, but again I dont see the significant difference with my quads.

Some pilots even claim that H frame should be better because the increased distance between front and rear arms allows rear props to get "clean" air, thus increasing performance. Check shendrones orca history - they actually went from x-frame to h-frame in this new design, and I own 2 mako (similarly looking true-X aeropod).

I came to conclusion that the most important qualities of fpv racing machine are (in order from the most important to least important):
1) reliability, durability, easy maintenance and parts availability; how well the frame can protect the internal equipment;
2) FC/ESC/motor quality and performance;
3) fpv gear and tx/rx quality (both airborn and ground equipment - VTX/VRX, antennas, camera, goggles/monitor);
4) flight battery quality and performance;
4) weight - 300-320 gramm on 5 inch (without battery) is a sweet spot, you can run lightweight 2204 motors without sacrificing the performance; if the frame is heavier, then you will have to compensate that extra weight by installing more powerful motors (2205-2206), but look! we are increasing the weight also. I run triblade 5050BN on 2204-2300kv rotorgeeks motors and the quad (330g with leds and transponder) is ballistic and I can actually squeeze 2.5 minutes out of 1300mah 4S SMC battery on a track. 2205-2300kv will make you choose bigger and heavier 1550mah battery or you will run out of juice before you finish the usual 2.5 minute heat.
You see I havent mentioned the frame layout, because I do not honestly think it is important. Most important things are how good you are as a pilot and if you can trust your equipment. That's my opinion.
Last edited by Wrecking Ball; Jul 26, 2016 at 01:53 AM.
Jul 28, 2016, 09:45 AM
Registered User
I think for competion, an x wins. Less angular momentum.

Otoh, for people that just like to fly race style, or freestype, the H is more more easy to build on, and can offer much better protection for the compoments. My H wont ever pitch or yaw as fast as an X. But on rolls, it wins any day xD

Imho the difference is so small, that the better pilot wins with either.
Jul 28, 2016, 10:37 AM
Team AlienWarpSquad
Quote:
Originally Posted by Wrecking Ball
You see I havent mentioned the frame layout, because I do not honestly think it is important. Most important things are how good you are as a pilot and if you can trust your equipment. That's my opinion.
Quote:
Originally Posted by Rabenklau

Imho the difference is so small, that the better pilot wins with either.
^^^ yep, that is what makes the difference.

Another point not mentioned in discussions above is:
How rigid the frame is especially with high power setups. If the frame flexes then it will not fly well. This is one of the issues with many 'clone' frames like the ZMR's compared to the BlackOut and also the Alien's compared to some of the cheap clones.
I have an Alien and it does fly way better than my two other frames (H style), but rigid is one thing this frame has.
Not to say don't buy those cheap frames as they are great when a beginner or as a bash around quad.
Jul 29, 2016, 08:38 PM
Registered User
We have done a lot of testing with our X frame with regards to battery placement and find that the battery place close to the prop center line helps with rotation from one flight direction to another.

We find not landing on the battery is a Plus as well.

We have been able to get the weight down to 317 grams by replacing the steel prop nuts with aluminum as well.

225 MM frame
Viper 225X
Aug 26, 2016, 07:20 PM
Registered User
Sure, true X frames (pod style ones with the lowest drag/weight etc) will go faster and roll quicker, but something I have noticed is that x frames never seem really seem quite locked in and smooth for freestyle/acro.

At first I thought it would just be down to the tune, but lot of people suggest that it is more about the distribution of weight. Something about having weight spread out along the pitch axis that gives them certain stability in flight that provides fluidity/smoothness that some people (me included) really like.

If you don't believe me, go watch videos from top pilots doing freestyle on long-base frames (people like johnnyfpv) and then go watch another top pilot doing freestyle on a true x (pod style) frame (zachary thayer who won the us nats for freestyle etc) and there is a distinct difference in how the quads handle in the air.

Just a musing, but it is affecting whether I'm gonna get a helix (or similar) or a more acro-orientated frame for my upgrade from my zmr.
Aug 27, 2016, 01:33 PM
Registered User
Scratchbuildrc's Avatar
Quote:
Originally Posted by gryffcook
Sure, true X frames (pod style ones with the lowest drag/weight etc) will go faster and roll quicker, but something I have noticed is that x frames never seem really seem quite locked in and smooth for freestyle/acro.

At first I thought it would just be down to the tune, but lot of people suggest that it is more about the distribution of weight. Something about having weight spread out along the pitch axis that gives them certain stability in flight that provides fluidity/smoothness that some people (me included) really like.

If you don't believe me, go watch videos from top pilots doing freestyle on long-base frames (people like johnnyfpv) and then go watch another top pilot doing freestyle on a true x (pod style) frame (zachary thayer who won the us nats for freestyle etc) and there is a distinct difference in how the quads handle in the air.

Just a musing, but it is affecting whether I'm gonna get a helix (or similar) or a more acro-orientated frame for my upgrade from my zmr.
I agree, I voted for an h frame for racing because you want to be really locked in on the long runs, which is something I havent seen with x frames. I would definitly build an x frame for freestyle though..
Sep 05, 2016, 02:06 PM
Registered User
Quote:
Originally Posted by airsiler
We have done a lot of testing with our X frame with regards to battery placement and find that the battery place close to the prop center line helps with rotation from one flight direction to another.

We find not landing on the battery is a Plus as well.

We have been able to get the weight down to 317 grams by replacing the steel prop nuts with aluminum as well.

225 MM frame
Viper 225X

Is this the same frame in the photo below? I found it on Armatten's site.. If so, which one is the latest iteration? Or are they dif models?


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