Morning All Backers,
Wishing you all a happy holidays.
We would like to start by sharing our launch video with you (homepage of website), we ask that you please don't share it publicly as this will only delay the launch further:
In regards to the progression of vehicle development, with every test session we are learning something new, as as the vehicle becomes more and more reliable - new issues start to arise that need addressing. I would like to take you through a few of them.
- Bogey center track engagement
We have found the addition of guides on the center engagement helps significantly to reduce the number of track throws. While on dry and smooth surfaces such as roads, sand, dry grass ect... this works very well. As soon as the vehicle was used on wet sticky mud / wet grass they would bind up the tracks and cause motors to overheat.
These have been significantly developed over the last 4 weeks to a solution that tries to minimize compromising the effectiveness of the engagement, while keeping binding problems to a minimum. They are also now easily removable should a user decide to run the vehicle on surfaces that cause build ups of debris.
- Thermal Management
The vehicle being a sealed metal chassis, cooling of the motors, batteries and ESC's has been a challenge. Due to several other issues, we never experienced the full extent of these problems until we were able to run the vehicle for long enough to experience them. Immediately running a second set of batteries was near impossible due to the residual heat from the first 30mins of running.
We developed our own thermal datalogger to monitor temperatures of ESC's, motors, intake, internal and exhaust air to help develop a cooling solution.
Over 60H of testing was conducted and 2,300,000 datapoints collected. A solution was found:
Open air - our stock setup, how the vehicle was run up until this point
open air x2 cooling solutions tested, both significantly outperforming stock setup
Sealed chassis, further analysis
- Electronics Issues
Ever since Hobbywing released the Gen 3 version of the electronics, we have had consistent ESC failures. Significant effort has been made ensuring the thermal performance of our cooling solution is adequate as shown above - hence eliminating thermal problems as a cause of this.
Currently trialing Castle electronics and have had another ESC let go. With the ESC's being the unlikely failure point; we are investigating further but yet to find the cause. We are in contact with both Hobbywing and Castle trying to find a solution and a possible reason for the failures.
- Cab strength
While the cab failing is not a functional issue - it would be rather annoying for our customers. This has been addressed with the addition of a roll cage. Designed and made in the last 2 weeks:
We have established a change we wanted to make to this design and it is currently being manufactured.
- Drive wheel strength
The drive wheel has been SLS printed nylon for the last 6 months but after a number of failures we have made the decision to upgrade this to machined extruded nylon. This is significantly stronger by at least a factor of 2.
Have been trialing a few options for upgraded color options should users want it. Example of a hard wearing anodized coating:
With the first snowfall in the UK this month, it was an opportunity to test the vehicle in the snow for the first time.
Unfortunately significant design concerns were brought to our attention to do with the drive wheel. Snow would compact in the central track engagement, compact, melt, then freeze and form ice. We will be addressing this with some new design options & confident the proposed solutions - however, with snowfall very unpredictable in the UK, we will need to figure out how to test this.
The new extruded & machined wheels are a much smoother surface than the textured SLS nylon wheels, so this may be enough to stop snow from sticking alone.
- Wiring & electronics
We are manufacturing custom PCB's and wiring looms for a better user experience & control.
That's all for now, along with what we are working to fix over the next weeks.
Happy Christmas from Xtreme RC!