Author: cjois

A trip down aviation history

~ cjois

EAA’s Airventure at Oshkosh, WI for most aviators is a unique experience each year. The event is the same, the venue is the same, most of the stalls are the same. Yet, nothing about AirVenture each year is the anything but the same. This is one of the reason why 700, 000 plus visitors come to Oshkosh, WI each year. I have personally been there every year since 1997 (when I moved to Chicago) with the exception of perhaps a couple years when my work called for trade overseas and I wasn’t in town to make the trip. Other than that, I do my best to ensure that the third week of July each year is blocked off from anything that needs me to travel away from Oshkosh.  This year, I went in mid-week for my annual pilgrimage to AirVenture. But by evening I knew I hadn’t had enough. So, I woke up really early on Saturday morning and went back again! It was a scorcher of a day. A heat index of 96 degrees. Really hot. But few things deter aviators or those with an aviation passion from doing the rounds at Oshkosh. I was proud to be one of them. 

On this trip though I took a slightly different route around the grounds. They say that the cosmos has nice surprises in store for those who take the unbeaten path… and indeed it had. I struck upon a used parts stall. The inventory of used, discontinued parts was unbelievable. I have been to another such store in Chicago, but to find a store like that in a airshow/convention venue was just a surprise. I couldn’t resist the desire to walk inside. What as meant to a quick 5 min browse, turned into 90 minutes of looking at all of these gauges, fan blades, props, dash mounts, even a few seats from old airplanes. Amongst all of those, my heart got set on two things. One of them was a Gables radio – a NAV unit.  The other was very interesting. It was a display cum control unit for a Rockwell Collins Doppler Radar Navigation system.  An analog computer! I was just amazed by the very construction of this panel. A piece of aviation history! It go me so interested that I waited to get back home and start searching for what it did or how it worked. What follows below is the result of the research.

The panel was part number 162C-1 of a larger ecosystem that collectively made up the Collins Doppler Radar Navigation System. The part was made in 1959.  Upon further research, I found a few different interesting facts.  A full description to come in future posts. 

Thx, CJ

Building a Motion Platform – the basics

~ cjois

For many years now, building a motion platform for a recreational flight simulator has been on my mind. Extending a home-built recreational simulator with a motion seat or motion base is nice science project but is also a meaningful extension to the study of the simulators. Three years ago I had built a small servo-based model of a motion platform with 2 degrees of freedom (2DOF).

https://youtu.be/PFR2ZPfaMWM

Three weekends ago, I started down the path of figuring out a design to make a scale version of a motion platform.

There are several parts to the development of a motion platform that can connect to a PC-based simulation engine. I have had very little experience with any of these steps and so it had to be learning by doing.

The overall set of steps are as follows –

  • Determining how to communicate with a real servo or motor or actuator 
  • Determining whether to use motors, servos or actuators
  • Validating the hardware cards that could interface between a PC and those motors or actuators
  • Writing code to drive those cards that drive those actuators or motors.
  • Powering actuators or motors or servos
  • identifying the right actuators or motors or servos that will serve the platform build
  • Connecting the actuators to the interface cards and then to the PC
  • Writing test code that tests the actuators
  • Connecting the game to simulation platform engine
  • Connecting the platform engine to hardware driver engine
  • Acquiring and transmitting telemetry to the chain above so as to be able to get the game’s motion to reflect realistically on the actuators.

Note that none of the above yet even discusses the build of a platform base or seat. This is just the work that is needed to get the concept validated.

For the simple prototype I chose to go with Progressive Automation for actuators. I also chose to go with MultiMoto Motor/Actuator driver. This card would seamlessly integrate with an Arduino chip. I picked up the LA-14P actuator from Progressive because it had built-in feedback. Needed a power supply and used my 10 Amp, 12V power supply that I use to charge my RC airplane batteries.

Until next time…

CJ

Winter Afternoon Flight

~ cjois

It’s felt great to get up in the air again after hibernating in sub-zero temperatures for over a month. It was crystal clear day. A few bumps here and there but overall a swell day to fly.

The snow had more or less cleared out after a couple above-zero days last weekend.

Traffic was heavy. Everyone wanted to fly, I guess. The Garmin 530, prompted by ADS-B technology was indicating traffic objects constantly. I wished I could have stayed up in the air for viewing the sunset.

Overflew the field at 2500ft before turning downwind for Runway 20.

The DJI Mavic Air

~ cjois

The DJI Mavic Air is one of many DJI UAV products. The Mavic Air is best known for its portability and serves the high-end hobbyist and serious enthusiast range of users. DJI has implemented some very unique design ideas to make the drone portable.

The Mavic Air folds up for storage, is very well built and looks aesthetic. The Mavic Air weighs just under 1 lb. and is very easy to carry around. The Mavic Air shoots 4K videos at 30 fps and still picture capture is performed at 12 megapixels. This works very well for its intended audience. The Mavic Air has a battery endurance range that results in flight times between 18-21 minutes. Strong winds alter battery endurance ranges. In terms of line of sight range the Mavic Air has a 2.5-mile control range using the remote. The drone comes equipped with internal and supplemental storage, the Mavic Air has 8GB of internal memory. The USB-C port allows for transfer of files. The supplemental microSD slot has support for microSDHC and microSDXC media. For power charging, the remote requires Micro USB and the drone has a USB Type-C port to transfer footage.

The Mavic Air is equipped with GPS and GLONASS satellite positioning. The GPS sensors are accurate and reliably enable automated and semi-automated flight modes. The Mavic Air performs well in steady hovering. Its GPS sensors make the ‘return-to-home’ safety feature very reliable. Location detection enforces no-fly zones and is once again very reliable. For example, the system will alert you to get authorization before flying at an airshow location with a TFR around it. There are a number of warning levels. Some warning levels can be overridden with necessary authorization and there are others that can’t be overridden.

The drone supports QuickShots. These automated camera shots move the drone through the air in a predetermined pattern such as a helix or spherical shot and allow for quick capture of the surrounding. This improves productivity and reduces the amount of manual programming needed to get the footage. Even with forward and rear obstacle detection, QuickShots must be used with care. In the QuickShot modes, the drone flies itself, and there is always a risk of collision.

The Mavic Air will fly at 17.9 miles per hour with obstacle avoidance enabled, or at up to 42.5 miles per hour in Sport mode, a mode in which the obstacle detection system is disabled. With a climb rate of 13 feet per second in Sports mode and 5 feet per second in Positioning mode (both using the Remote Controller), the Mavic Air is found be very useful in most situations.

The maximum service ceiling for the Mavic Air is 3.1 miles above sea level. One of the important considerations with regard to UAVs or drones is their wind resistance capability. The DJI Mavic Air wind limit is 22 miles per hour. Beyond this number, the Mavic Air will generate a warning for high winds. This can be somewhat limiting in certain circumstances. The Mavic Air’s obstacle detection and avoidance system is very much reliable. The Air has forward, backward and downward sensors. The Advanced Pilot Awareness System (APAS) leverages all of these sensors. Coupled with this intelligence, instead of simply hovering in place when it detects an obstacle blocking the drone’s path, the Mavic Air explores the situation and automatically adjusts flight to avoid it, either by flying to the side or rising above it.
Burdziakowski, P. (2018). UAV IN TODAYS PHOTOGRAMMETRY–APPLICATION AREAS AND CHALLENGES. International Multidisciplinary Scientific GeoConference: SGEM: Surveying Geology & mining Ecology Management, 18, 241-248.
DJI Mavic Air. (2019). Retrieved May 5, 2020, from PCMAG website: https://www.pcmag.com/reviews/dji-mavic-air
Fintan Corrigan. (2020, January 13). DJI Mavic Air Features Review, Specifications and FAQs Answered. Retrieved May 5, 2020, from DroneZon website: https://www.dronezon.com/drone-reviews/dji-mavic-air-review-features-specifications-faqs-answered/
Yousef, M., Iqbal, F., & Hussain, M. (2020, April). Drone Forensics: A Detailed Analysis of Emerging DJI Models. In 2020 11th International Conference on Information and Communication Systems (ICICS) (pp. 066-071). IEEE.