I'd like to show the forum members the new 500X4 Carbon Quadrocopter.
It is 500mm motor centre-to-centre, weighs 330g,
and has a sliding-locking battery tray typically used with a 3S 2500 pack.
It's the same tray used on the larger multis that can accomodate 6S 5800's.
Can take 30mm motors.
There's no Assembly Guide at this present time sorry, but they are very easy to build and very similar to the larger X4650 and X4950 which does have an Assembly Guide.
I went to the link and have a comment on its design. Please take what I am saying as constructive and not a criticism. The method that you are using to connect the arms to the core appears to use only screws going from the top deck plate, through the carbon fiber tubes, through the lower deck plate. Given the extraordinary vibration of multi-copters, this style of mounting arms will cause two problems after an extended number of flights.
First - The screws will become small files and create larger holes in the deck plates over time.
Second - As the holes become larger you will have an issue in that the arms will begin to rotate which will cause the motor alignment (vertical) to start changing which will cause the thrust vector to also change on those arms that begin to have larger screw holes due to the file/wear affect. This will eventually cause a yaw to occur.
I would consider using clamp mounts like those used in the Droidworx products. They have an alignment stub that fits into an alignment hole at the inside end of the arm which ensures that the motor mounts are exactly verticle and prevent any rotation of the arm even with high flight times. The arn is secured via clamping vs. a screw through all the parts.
Just an observation. Please take it as it is intended - to make a better and more reliable airframe.
First of all, flight time on model helicopters has little bearing on one’s capabilities in aerospace engineering design. Secondly, your hypothesis that the use of carbon fiber infused polymer clamps (CFRP) is added weight is technically correct – however, one set of clamps (outside and inside sets) is 8 grams. Therefore on a quadracopter, that amounts to 32 grams of weight or 1.1 ounces – an insignificant weight when you consider the intrinsic benefit that it provides. The real issue is this; a major consideration in aircraft design for both the hobbyist and the commercial user is survivability and reconstruction costs following a crash. Your design ensures that any moderate crash will result in one or more of the following: 1) The “bolts” shearing and with that failure the real possibility that the “glued” nuts will also detach. 2) The upper and lower mounting plates fracturing due to extreme sheer and torque forces caused by the leverage of the arms twisting against the miniscule binding area between the arm and the mounting plates.
When using clamps you benefit from the distribution of shear and torque forces throughout a much larger surface area of binding between the two horizontal center plates and the significant area represented by the inside of the clamps. If you want to verify my hypothesis, mount two adjacent arms using your design with “bolts” and apply a strain gage while compressing one arm against the other until failure. Then measure the same setup using clamps with only 2 thru-bolts vs. the 4 in your design. Look at the difference in damage. (I already know the results)
Your comment that, “locating-studs . . . . start to melt over time” is remarkable. The clamps I referenced in my earlier comment are carbon fiber reinforced polymer (CFRP). The melting temperature of carbon fiber is approximately 1200 Celsius (2,192 F). Polymers on the other hand have lower melting points. A common polymer used in the aerospace industry and coincidentally, used in the clamps I have referenced is Nylon 6,6. It has a melting point of 265 degrees Celsius (509 degrees F.) If you believe that the alignment nub molded into one side of the clamp assembly is going to melt around the arms of a multi-copter, well all I can say is you must have placed the fusion reactor next to the mounting clamps.
Finally, there are normally two keys to a financially successful product assuming there is a market for that product. 1) Cost of manufacture and 2) reliability. One could also argue that the cost of repair is also a key financial consideration, especially in the hobby and aerial photo markets. Using “glued captive nuts” not only is expensive and time consuming in the assembly process but does nothing to deter the sheer and torque forces on the small contact area between the arm and the upper and lower mounting plates. The actual contact area of one arm in your design has less than ¼” square of area whereas using clamps increases the sheer and torque distribution area to over 3 square inches. Physics and math do not lie.
Best of luck.
I just purchased a Carboncore Hexa 950mm. I will report my findings as soon as I fly it. The arms are not round, but rather rectangular with rounded corners.
Allen, it almost looks like the bolt on arms may be a calculated failure point. It is one of the cheapest and easiest pieces to replace. I can tell you for sure that the plates are not going to fail first. I work in the custom car and race car industry and I have seen all kinds of carbon and Kevlar pieces and the plates are some of the densest carbon I have ever handled. But time will tell and I will share my findings. The nuts are a pain in the ass to glue properly but most the fun is building and tuning anyways.
The carbon plates thes kits are cut from is very hard stuff. It is made by a car composites workshop. Very few customers have bought frameplates as spares. The motor moutns are normally the first thing to hit the ground in a mishap.
Some new carbon pieces are now included in the kits to help install the captive nuts.