This will be the project that will refine the final production design.
Update June 22, 2018: Did a couple spontaneous speed runs on 4S and 5S with APC 5045 BN props. Never got to the APC 5050 or 5260’s due to rain.
Update June 20, 2018: This will be worth the wait. The line up is finalized, but not quite polished off and won’t be fully available at launch. The plan is to launch the 5″ race frame sometime next week and at the same time, take preorders for the rest of the line up. However, I am leaning more towards a “build your own ARX” instead of complete kits since all frames (at least the initial line up I have) will be interchangeable.
Update May 30, 2018: This is definitely a challenge. I have spent nearly 100 hours with the CAD models. Things have changed, but progress is definitely being made.
Update May 13, 2018: A lot has been accomplished and the design and the frame line up is just about finalized. The vision I had for the frame has finally taken shape. It took a while but it was worth the wait. Although there have been several prototypes already built, they sacrificed too much in terms of construction and ease of repair.
When Simple Isn’t Simple
I strive to make designs as simple as possible. However, the simplicity made for an atrocious outcome: repairs pretty much meant a complete rebuild. So now, the core design is a little more complex than I would have liked but the result is much better than before: repairs are now simple. When an arm breaks, only 1 or 2 motor screws have to be removed to replace it.
Test flights have been done on the previous (simplified) race version which has a cross section of only 3mm for each arm (12mm total). The concept worked with no issues and feedback was very positive.
Virtual Reality Specs
In CAD, it looks like a happy frame but there still has to be a reality check. This should be next week when the prototype arrives. So right now, this is a preliminary/virtual reality overview of the ARX:
Naming convention: ARX-AB C-D where A is the frame type, B is the prop size, C is for miscellaneous, and D for version number (none for the first).
As of now, there are 5 types planned, however, only the 5″ race frames will be available at launch:
- ARX-5R 4S: 4S Race Frame – 3mm total cross section arms, approx. 45g
- ARX-5R 6S: 6S Race Frame – 3mm total cross section arms, also approx. 45g
- ARX-5F: Freestyle Frame – 6mm total cross section arms, should be able to handle both 4S and 6S
- ARX-5S: Speed Frame – this one will take awhile
- ARX-5L: Lightweight Frame – 2mm total cross section arms, approx. 25-30g
All 5 types will come with stretch mounts which gives ability to quickly change arm shape to fine tune the feel: stretch X, wide X (correct name?), true x, deadcat, etc.
All 5 frame types have parts that are interchangeable with one another. For example, if you already have one type of frame, you can get a “mod pack” that will alter it into a different frame type.
Different arm thickness and length sets (thicknesses to be determined) will be available. The sets also include the required spacers that are specific to that arm thickness/length.
Arms can also be purchased individually if you already have the spacers.
One More Frame – The Time Frame
I hope to get things done and finalized by next week. Keeping everything interchangeable has taken up a lot of time but the base design is almost done.
Also, I have no idea what the demand will be like. Will it be popular? A novelty? Or will it be crap? That’s hard to determine so I’m unsure of how to do this. More than likely, I will do the pre-order thing which will give me an idea of the demand and get the ball rolling. If everything goes smoothly, I hope to start selling in 3-4 weeks.
Update April 11, 2018: Almost ready to have some CF cut for 2 different prototype production designs. I’ve also been toying around with this idea: adjustable between 5″ frame and 6″. Also, adjustable between a true and stretch x. I’ll have to look at it more in CAD, but this looks like a real possibility…
Update March 31, 2018: Design for the first production prototype is 99% done, I just need to review it and double check a few things.
- Calculated dry weight is 24g – I like this but I also don’t like this since I value a strong, crash proof frame. If it ends up being strong enough, great. If not, this could go up a little but I don’t think anymore than 30g total.
- Weight including motor screws, FPV cam screws, and battery straps is 28.5g
- Motor to motor distance is 209mm (this might get reduced just a tiny bit)
- True X design
- Inverted front motors
- Geometrically centered and vertically mounted battery
Update March 26, 2018: Design for the first production prototype is almost done and I hope to send out the drawings for quote in the next week. Once I have the physical frame in my hands, I’ll iron out any issues and go from there. I just need to figure out the FPV camera mounting which will probably be limited to the 20 x 20mm micro size cams.
Weight right now sits at just a little under 30g, but that includes motor screws (aluminum) and battery straps.
Speaking of battery straps – no Velcro, just 2 o-rings. Hard to explain with words, but it will be cleaner and I would like to call it a “quick-change-system”, but the preliminary mock up I did at home had mixed results: it definitely worked great, quicker than Velcro, but not exactly super quick.
March 18, 2018:
Fleshing It Out
Exact details are still wishy washy. Since the XLR project is going be wrapping up next week, the floodgates will open to get this one fleshed out a bit more. Regardless, I took a little time to throw together a few prototype frames today – there are many directions to go with this frame.
The Last Design Hurdle
This is what is comes down to: the weight vs strength game. The design is the strongest frame (gram for gram) that I know of so far. But like any frame, where is the cutoff point? How “weak” should I let it get? To make it worse, this will depend on how easy it is to replace an arm.
Finally Some Info
- In a nutshell, the main thing is the construction method of the arms (patent pending). They have a total width of 3mm but are still extremely strong. This means less thrust is blocked = quieter = faster acceleration = faster top speed = longer flight time.
- There is a small possibility the arms could go as thin as 2mm (pending tests).
- The arm design also allows the battery to be mounted vertically and central to everything: half above the arms, half below. This minimizes the moment of inertia by bringing the mass distribution into a more compact area. This meas faster angular acceleration = less energy is needed to reach target gyro speeds = faster response = longer flight times.
- Due to the “open frame” design, the frame is extremely versatile – in fact, it was brought up by another developer (with an NDA between us) that the design could easily be applied to break the speed, 100m ascent, payload capacity, endurance, and distance records.
Specs (very loose):
- I had hopes that this would be a crazy light frame, but for many reasons, It will be right around a 40g frame for the 5″ basic frame – this is still very up in the air. If anything, it will drop, as low as 30g or 25g.
- Initially, the frame(s) will be 5″.
- 3 (or more) different versions of the frame:
- The basic 5″ true X frame (roughly 30-40g?)
- The basic 5″ stretch X frame
- The Ultralight 5″ frame (roughly 20-30g?)
- Also, initially only full frame sets (along with spare parts) will be sold. Eventually, add-ons will be sold so an XLR type quad could be built.
- The frame is designed to work best with separate ESC’s.
- A lot of things will be clearer by next weekend.
The Prototype Pilot
Obviously, I can fly a quad, but my flying is nothing exciting. To get a true feel for how the frame will be in the hands of a good pilot, I’ll be giving a prototype frame to MetropolisFPV so he can give is a spin and compare it to other frames he has flown. I will eventually hand out 2 or 3 more to get some more feedback. A couple of MetropolisFPV’s videos:
Please feel free to ask questions – I’ll answer if I can and it may help clarify final design parameters.