UAS Challenge FAQs
Get answers to frequently asked questions in preparation for the next UAS Challenge competition.
Airframes: Ready-made or made for the competition
Question: Are we allowed to use ready-made frames/structures for our unmanned aircraft or do we make it from scratch?
Answer: The UAS airframe and physical control systems shall be designed from scratch, and not based upon commercially available kits or systems.’’ The airframe and control systems design should be your own and not a copy of a commercial UAS. We are looking for innovative ideas.
Batteries
Question: In the batteries section (T3.1.1), it states that 6S 6000 mAh Li-Po batteries with XT90 connectors must be used. Would it be permissible to use an additional, smaller-capacity battery dedicated solely to powering the servos and auxiliary systems, or must all power be supplied from the main battery pack?
Answer: No, only 6S 6000mAh batteries are permitted.
Clarification on Pilot licenses 4.6.1
All flying at the competition event itself will be conducted by the event Safety Pilots and the Flight Safety Officer. The team’s pilot will not fly your UAS at BMFA Buckminster. In terms of your own Pre-Demonstration event practice and testing, teams need to comply with their local Aviation Authority regulations. In the UK that is the Civil Aviation Authority and the UK Air Navigation Orders for safe and lawful flying.
In summary UK teams must ensure the following:
- That they or the University hold an Operator ID form the UK CAA and that said number is displayed correctly on their aircraft.
- That any person flying the aircraft meets the competency requirements set out by the UK CAA, which is typically the Flyer ID element.
- That any flights are only performed under UK CAA regulations, i.e. that they fly safely and lawfully. As they are likely to be flying aircraft near 10kg, this will mean they are likely to be flying in the A3 Open Category.
There is no official need legally for insurance unless any flights are considered ‘commercial’, however the IMechE do require that teams use insurance, for which the British Model Flying Association can help (www.bmfa.org).
A quick start guide on regulations can be found here: https://rcc.bmfa.uk/quick-start-guide-to-model-flying-operation-of-unmanned-aircraft
Commercial flying is often considered a flight performed for payment or reward, but if the pilot is a paid member of staff, that also makes it a commercial flight.
International teams:
International teams will need to comply with their relevant Aviation Authority regulations, which may differ to those in the UK
Communication frequencies and power ratings
Question: What radio frequencies and transmitting power ratings are legal to operate for airborne use in the UK?
Answer: The allowable frequencies for airborne use are specified in Ofcom’s IR 2030 Licence Exempt Short Range Devices: https://www.ofcom.org.uk/spectrum/radio-equipment/short-range-devices (see T4.4 of the rules).
The relevant entries are:
For control of the aircraft and for the FTS:
IR2030/7/1 - 2400 – 2483.5 MHz - ≤100 mW e.i.r.p. frequency hopping
For telemetry:
IR2030/1/10 - 433.05 – 434.79 MHz - ≤10 mW e.r.p. (10% duty cycle limit)
IR2030/1/14 - 865 – 868 MHz - ≤25 mW e.r.p.
IR2030/1/23 - 5725 – 5875 MHz - ≤25 mW e.i.r.p.
COTS Budget
Question: The COTS products budget is set at £1300. I am aware this includes off the shelf components such as motors and batteries etc. Does this also include all material and manufacturing costs too? Is the cost of either the sandwich panel itself or the associated manufacturing costs included in this COTS budget?
Answer: The rules state that the guideline maximum value of COTS is £1,300; it is not a limit but we are looking for the best value for money (competitiveness) of the UAS. COTS, in this context, is for bought-in finished components, e.g. motors, batteries, servos, control boards, etc., (see T2.4.3 of the rules). Any expenditure above the £1,300 needs to be justified. You are not limited to what you spend on materials but you do need to consider whether an aid agency will be able to afford your UAS for delivering the humanitarian aid. We will be judging your business case from your Business Presentation. You also need to consider the environmental impact of the materials that you are using.
COTS structural components
Question: What COTS structural components are permitted?
Answer: Rule T2.4.5 states that “COTS composite components including constant profile spars and beams shall not be used in the construction of the air vehicle”. You may, however, design and make your own spars, beams, etc., from composite sheet material (T2.4.3). You may also buy off-the-shelf aluminium sections, but you should demonstrate that you have done the necessary structural analysis to justify the gauge and section of the component that you have bought. The cost of these aluminium sections should be included in your COTS budget.
COTS structural components
Question: What COTS structural components are permitted?
Answer: Rule T2.4.5 states that “COTS composite components including constant profile spars and beams shall not be used in the construction of the air vehicle”. You may, however, design and make your own spars, beams, etc., from composite sheet material (T2.4.3). You may also buy off-the-shelf aluminium sections, but you should demonstrate that you have done the necessary structural analysis to justify the gauge and section of the component that you have bought. The cost of these aluminium sections should be included in your COTS budget.
Deliverable documents: Structure and content of deliverable documents
Question: Section D specifies the structure and content of the deliverable documents: is this mandatory or guidance on how to cover the subject matter?
Answer: The content specified in Section D for all documents are mandatory. Failure to follow these requirements may result in the document being declared ineligible.
Design Changes
Question: Once the concept paper is submitted, how much is our design allowed deviate from it In case we encounter problems?
Answer: You may make detail changes to your design at any stage as your design evolves and as testing raises issues. You must list any significant changes with an explanation of why they have become necessary in your next document release. These changes should also feature in your Design Review meetings.
Electrical power system – energy source
Question: Is it permissible to use power sources other than Li-Po batteries e.g. hydrogen fuel cells?
Answer: No, only Li-Po batteries may be used as stated in T3.1.
Electrical power system – removable link
Question: If we have a two-engine design does it need to be one isolator, or can a two-engine design run on separate circuits with one for each engine?
Answer: The requirement for the external removable link is for the safety of the operator and so that the Scrutineers and Flight Safety Officer can see that the aircraft is in a safe to handle state. A single link disabling power to all motors and positioned as specified in T3.2 See also the whole aircraft isolation link requirement in T3.2.
Energy efficiency calculation for the Long Mission
Question: How many of the waypoints are included in the Energy Efficiency calculation for the Long Mission?
Answer: For the Energy Efficiency in the Long Mission, all the waypoints navigated will be included to make it fair to all teams. The calculation will assume that you carry the full payload around the maximum 10 waypoints to the first release point, half the payload around the waypoints to the second release point and no payload for the return navigation circuit to landing (e.g. ((Start payload x waypoints to first release point) + (0.5 start payload x waypoints between first and second release point) + (number of waypoints from second release to landing)) / Energy consumed). The points awarded are then allocated according to the table in F3.6.8.
Flight demonstration: PPE requirement
Question: Could you please provide a full list of all PPE that the team will require to be compliant with your risk assessment?
Answer: All members involved in the launch and recovery of the UA are required to wear safety glasses. Other PPE requirements will vary for each team, depending on what tooling will be used at the event, therefore, no specification will be provided by the IMechE; if we did it would state “all PPE required for the tasks to be performed”.
Teams should be advised to consult the Health and Safety Executive (HSE) guidance for PPE at work and demonstrate to the IMechE that they have selected suitable PPE for the maintenance/manufacturing tasks they will be performing, as part of their own Safety Assessment/Risk Assessment. Appropriate use of PPE will be monitored at the Demonstration Event.
Funding: Backup components
Question: If we acquire backup components for the build that may not be used in the final system during the flight missions, should we include it in the budget/ cost declaration?
Answer: No, you need not declare backup components in your cost budget but you may want to mention that you have taken the precaution of buying some as a risk mitigation.
Funding: Declaring sponsor's assistance/costs
Question: We have a sponsor who will be helping us fabricate our frame. If we have to, how do we declare the costs associated with this?
Answer: You need to clearly state what work your sponsor is doing for you. Please take particular note of the words in sections 5.3 and T2.4 of the Rules.
The idea of the competition is that this should be your own airframe and control system design and aside from off-the-shelf components, e.g. autopilots, batteries, motors, etc. should largely be manufactured and assembled by yourselves.
If it is a specialised component/assembly from your sponsor then it should be included in the COTS budget. If the sponsor is helping with specialised manufacturing equipment then it need not but should be acknowledged.
Funding: Backup components
Question: If we acquire backup components for the build that may not be used in the final system during the flight missions, should we include it in the budget/ cost declaration?
Answer: No, you need not declare backup components in your cost budget but you may want to mention that you have taken the precaution of buying some as a risk mitigation.
Funding: Financial assistance/grants
Question: Is it possible for the Institution of Mechanical Engineers to help our team financially in order to cut down costs?
Answer: The Institution is not able to sponsor any UAS Challenge teams directly.
How will the UAS’ water tank(s) be filled at BMFA Buckminster?
Immediately before the aircraft moves to the flightline, judges will pour water into the UA’s water tank from a calibrated jug, with the amount of water requested by the team. The amount must keep the UA’s MTOW within the 10 kg limit. Once filled with water, the team will then load the tank into their aircraft, which is sat on the ground on its undercarriage, from above without the use of tools.
Manual handling assessment
Question: Why is the manual handling assessment on the third day as opposed to the first? It makes sense for a manual test to be the first to be done before deeming an aircraft worthy to fly autonomously
Answer: Manual handling is not an assessment of an aircraft’s ability to fly. That is up to you to determine to your own satisfaction prior to the fly-off. The manual handling assessment is to see how well you have designed an aircraft from a pilot’s handling perspective. They are on the last day because they take comparatively little time and the last day will have less time in which to complete the flights. Historically, we have seen many manual handling flights occurring on the last day.
Mission length
Question: T2.9.1 states that “The air vehicle shall be designed to fly for 15 minutes with 20% battery capacity remaining but ”F4.1.2 says that “All flights are limited to 10 minutes.” Why the difference?
Answer: 15 minutes is a deliberate sizing requirement. We are limiting mission times so that we can get all of the flying done for all of the teams in the limited space of time we have. However, if the flight is over 10 minutes, we don’t want to have aircraft dropping out of the sky, nor unnecessarily deep discharging in flight. You will provide the state of charge at the end of the missions for the purpose of efficiency calculations, and we will be able to calculate theoretical endurance then.
Mission scheduling
Question: Why are teams only allowed to do one mission a day and why are the missions restricted to a specific day? What would happen in the event of bad weather like this year? Would the slots be moved to the next day?
Answer: This is a scheduling limitation and an attempt to encourage teams to arrive with aircraft ready to fly. It is also an attempt to even out bad weather effects – i.e. previously a team may be able to complete all of their flights on 1 day whilst the others are affected by poor weather on subsequent days. Weather is always an operational risk/consideration. Sever weather will be managed on the day by the event staff – we will do our best to make sure that no-one is disadvantaged. However, whilst there are weather operating limits defined in the rules, it is always the team captain’s responsibility on whether or not to fly.
Payload Mass
Question: Is the "payload" mass that points are rewarded for purely the mass of water? And are teams allowed to not release the entirety of the water content until landing? i.e.: keep some water in store for CG reasons post both releases.
Answer: The mass used for scoring calculations is just the water. The intent is that all water is released during the course of the mission. It is understood that there will be some minimal amount of payload that cannot be released. However, as you are being scored on aircraft efficiency, and efficiency will improve as aircraft weight reduces, it is in your interest to release as much payload as possible.
Payload Release
Question: Regarding the water payload release (T5.2), the rules mention that it must be a continuous flow. Could you explain how “continuous” will be assessed during the event? Will there be any measurement method for flow rate, and is there a minimum flow specified for the release to be considered valid?
Answer: This will be assessed by judges on the ground. You should make your flow rate sufficient to be visible. It also benefits your aircraft to drop as much water as possible as your efficiency score will be negatively affected by carrying excess payload.
PDR and CDR submission dates
Question: We are required to set our own Design Review dates but D1.2 has a PDR deliverable date of 16th February and CDR of 20th March 2026. Which is correct?
Answer: Your design reviews should be held in accordance with D3.1.2, D6.1.2 and D7.1.2. You should upload your Design Review report to Mashoom immediately after holding the meetings. The PDR 16th February, and CDR 20th February, dates are the last acceptable date for submission. After these dates, the reports will not be reviewed or scored. These dates are set much later than when we would be expecting you to hold your Design Reviews.
Take-off
Question: You have restricted the use of launch assistance equipment. We understand that this restricts use of a catapult launch and a winch launch but are passive equipment like cast away wheels restricted?
Answer: No devices assisting in the launch of your aircraft are permitted. This includes unpowered launch carts. Any undercarriage must remain with the UA after take-off; nothing must remain on the runway.
Team composition: additional team members at fly-off finals
Question: If we want to add an additional member to the team (giving more than 8 people + supervisor) is this possible?
Answer: Team attendance at the Demonstration Event is currently limited to no more than 8 members per team, plus your Academic Lead or Team Supervisor. This is because of the expected number of teams and the logistics constraints at the BMFA Buckminster site. We will communicate any changes to teams as/when we are able
X Plane
Question: What version of X Plane do we use?
Answer: Please use X Plane version 11, which is available for free at https://www.x-plane.com/desktop/try-it/older/