Payload density & damage protection
The AirDropBox Micro UAS airdrop package is designed to protect payloads from 1-5kg in mass; this can be anything from a satellite phone, a radio or a temperature-controlled pack of vaccine or anti-venom vials all the way through to a set of small automotive parts, machine spares, a food package, first aid kit or small survival pack. Obviously the denser items on the list are also more resistant to damage generally, so we have optimised the impact buffer around a payload of about 2.5kg, at roughly half of the system’s maximum payload. Payloads that mass more than this will need to be tougher, or integrate a degree of impact resistance into their design. That’s not to say the impact buffer doesn’t offer protection to heavier payloads, but it is less effective as the mass increases.
It is also helpful to the efficiency of the impact buffer to ensure that payloads with uneven mass have their centre of mass as close to the impact buffer as possible, in order to aid with stability on landing.
It is worth noting that in order to reach a full 5kg payload in testing we used a box lined with plastic and filled with wet sand to the full height of the payload space- it’s not easy to over-load the system. The payload volume is deliberately limited in this way so as to prevent overloading the system as we anticipate many of our end users will be otherwise untrained in air drop.
Descent rate (sink rate)
Understanding the likely sink rate of a payload- particularly an unguided payload like AirDropBox Micro- is key to ensuring that any air drop is made accurately.
The AirDropBox Micro system will descend at a rate of about 11 metres per second with a maximum 5kg payload in the package; we anticipate most teams will want to use as high a payload mass as possible. More detailed data on sink rates at different payloads is available on request.
Minimum drop altitude
Another key factor in drop accuracy is deployment altitude for the system- the lower you can drop from, the easier it is to drop accurately.
The AirDropBox website lists a minimum drop height for all of our systems of 500ft AGL, because this is the altitude we did almost all of our testing at. AirDropBox Micro UAS is however designed to open much more rapidly than other AirDropBox systems, meaning it will almost always open and decelerate to terminal velocity within 100ft of descent; possibly as little as 70ft. However, there is always a risk inherent in dropping at lower and lower altitudes, as the parachutes will have some variance in how fast they open up and dropping too low can cause systems to hit the ground before the parachute can open fully.
The safe drop height could be made lower by having the parachute pack pre-opened in flight as discussed below, but this may not always be the case.
Static line/release lanyard length
The release lanyard requires a fairly sharp tug to break the stitch that holds the parachute pack closed. This shouldn’t be a problem for most systems, but you do need to bear in mind that there will be a short, sharp shock force applied to your system as the parachute releases- it’s not just the mass of the package you have to consider.
What is more likely to be a problem for some teams is the fact that the lanyard remains attached to the UAS after parachute release. The stock lanyard for the Micro UAS system is shorter than for the stock AirDropBox Micro (though some teams that requested their AirDropBox systems early did receive systems with the longer AirDropBox Micro lanyard attached), but it is still longer than most teams will need it to be, and for some this might present a hazard, either that the lanyard might catch on a control surface or tangle a prop, or that the lanyard might catch on the ground as the UAS comes in to land.
The good news on this front though is that there are options to mitigate this issue. The lanyard can be shortened significantly from its stock length, particularly if a heavier payload is used, without impacting its ability to release the parachute; with the stock closing loop material the minimum length is about 300mm. This may be reduced still further by replacing the closing loop with a weaker material, such as a thinner cotton cord. We are able to offer assistance with any such modifications you might require.
There is also the option of having the parachute pack opened prior to launching the UAV. In terms of real-world deployments where the AirDropBox system may or may not be dropped on any given deployment this isn’t ideal, as it would mean the system is essentially “used” regardless of whether the package is dropped or not, but it could significantly ease the issue of how to get the lanyard out of the way if it is simply not used. Obviously if you do this, the parachute must be kept folded up away from any airflow past the UAS so as not to accidentally deploy the parachute without dropping the payload, but we assume teams will pick up on that pretty quickly themselves!
Air resistance
Speaking of airflow, it seems likely that on a very small UAS the air resistance of the AirDropBox Micro system will be much greater than that of the UAS itself, if you leave it hanging underneath. For this reason, I suspect most teams will want to have the AirDropBox system enclosed, or at least “faired in” in some way, using lightweight fairings to reduce the impact on their system’s performance. This naturally creates its own challenges in terms of internal volume and layout for the UAS design, but we think overall it will probably be necessary. It’s important to consider what the aerodynamics of your platform are going to be like both with and without the AirDropBox system installed, though remember, your UAS has to come back without it. Some fairing designs may therefore not be completely suitable.
Considerations for your business presentations
When giving a presentation the most important thing is often to make sure that your audience remains engaged throughout, rather than attempting to cram as much information as possible into your slides and speech; if your audience becomes disengaged, they will stop paying attention to you and will not absorb any of the information you are presenting, which is a waste of your time and theirs.
It is therefore important to keep your slides as simple and visually engaging as possible, and try to limit the information you include in your speech to only the most important items; if your audience wants more detail about a particular item, they can always ask you later on. Keep the tempo of your presentation high and your voice engaged, and make sure you know as much about the subject as possible (more than is on the slides) so that you can elaborate on any given point if required.
Practice your presentation in advance in order to make sure you know it well and can run through it without hesitation and also to ensure that you can complete your presentation inside the allotted time. Practice talking through your presentation in front of a mirror, so that you can see how you will come across to your audience. Time your presentation and ensure you do not speak too fast because of nerves. Hand gestures can be important to add emphasis to points or draw attention to particular slides, but try not to over-use them or fidget with your hands, as this will draw attention away from your face and your slides, which is where you want your audience to be focused. If you can, leave some time for audience questions.
Don’t underestimate your audience: allowing them time to ask questions is hugely useful, as it allows you to limit the information you put into the main presentation to the absolute bare essentials. If something catches their interest that they feel you have not provided enough information on, they will ask you about it and you will know that you are not losing them when you provide that additional detail. This is another reason it is important to know as much as possible about your presentation topic, certainly more than you plan to say./p>