Mar.10, 2014
Small unmanned aerial vehicles (UAVs) are extremely flexible devices, and can often used in aerial surveys, photography and environmental monitoring. But most of the designs are expensive and time-consuming to produce. Engineers in The University of Sheffield Advanced Manufacturing Research Centre (AMRC) with Boeing's new Design & Prototyping Group has designed and prototyped an innovative small unmanned aircraft using advanced design tools and 3D printing technology.
The airframe parts were all printed using a fused deposition modelling (FDM) technology. To save material cost and building time, the AMRC team designed each part of the structure specifically for additive manufacture so that it can be printed without any need for support material.
"By understanding the capability of the FDM process and the associated software, we were able to manipulate the design to contain a number of unique features as well as preventing build deformation," says Mark Cocking, additive manufacturing development engineer in the AMRC Design & Prototyping Group.
Using Stratasys Fortus 900mc FDM 3D printer, the team was able to improve wing structures from a simple wing skin to a more sophisticated design with integrated stiffeners. A semi-monocoque internal structure helps prevent deformation during build, withstands aerodynamic loads in flight, and allows for easy assembly. "All parts required for the airframe can be combined onto a single build within our Fortus 900, taking less than 24 hours with ABS-M30 material," says Cocking. "Before design for additive manufacture optimisation, this airframe would take over 120 hours to produce."
"The optimum configuration for the diverse requirements of aerodynamic performance and FDM manufacture appeared to be the blended-wing body." said development engineer John Mann who led the detailed design. "This type of design has a number of advantages and, most importantly for this project, lends itself to FDM technology due to the smooth leading and trailing edges over each half-span."
The final airframe design allowed all features to remain below the critical angles beyond which support material would be required. It comprised only nine parts – two wings, two elevons, two spars, two wing end fences and a central spine – "all of which were designed to clip together with a pair of short spars attaching each wing half and providing additional rigidity, and snap-on elevons controlled by servos mounted in the aft of the body." notes AMRC. They were all 3D printed without support material.
All images: AMRC with Boeing
The team also used computational fluid dynamics (CFD) modelling to optimise the chosen design and assess flight characteristics such as lift, drag and pitching moment over a range of angles of incidence.
"The finished aircraft has a wingspan of 1.5 metres, weighs under 2kg, and can be easily split into two halves around the central spine for easy transport." explains AMRC.
In its first test in the Peak District, the aircraft showed good stability and low aerodynamic noise at speed. "Following successful flight testing, we are now further optimising the airframe to incorporate blended winglets and twin-ducted fan propulsion," says senior design engineer Garth Nicholson. "Future planned developments include full on-board data logging of flight parameters, autonomous operation by GPS, and control by surface morphing technology. We're also investigating concepts for novel ducted-fan designs."
Through partnership between industry and academia, the AMRC Design & Prototyping Group have demonstrated that design for manufacture of relatively large thin-walled parts can be optimised for the FDM process. The techniques of printing only build material with no support structure can provide significant savings in time and cost for specialist UAVs, such as those for helping search for survivors in disaster areas.
Posted in 3D Printing Applications
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FYI The full case study and test flight video clip is here: http://www.amrc.co.uk/featuredstudy/printed-uav/ Thanks for the comments!
Eli wrote at 3/12/2014 4:52:25 PM:
lots of people are doing FDM UAV's. the fact it was done without support is not new, but it's a nice airframe!
IzieaB wrote at 3/12/2014 1:21:11 PM:
Yru, 1. FDM was invented & patented in 1989, by the co founders of Stratasys. All other versions off FDM machines since then have appeared after key patents expired, the RepRap included. So in fact, 'we' (whoever we are..?) have always been behind if you wish to look at it that way. Although that notion is also flawed because at one point there were no players. 2. The RC sail plane reference really does not mean anything, the point is that the UAV as per reported article flew. 3. I cant be bothered to answer the others - read the article again...
yru wrote at 3/11/2014 10:13:45 PM:
IzieaB, it's yru by the way, I don't know what kind of printer you use, but in RepRap world trying to print without suport is standard, it's quicker and more "green". I made my own attempts in wing printing some time ago and they are quite heavy and still to slow to produce, plus it really asks for some custom slicer mods. Should realy publish those. Ask google for rc sail planes and weight, "Dave's Aircraft Works foaMe-163 Komet" for example. So for me, it's funny, we bring to the public the technology and always feel like being few steps behind the big players, yet in some aspects, it's quite the opposite.
IzieaB wrote at 3/11/2014 4:26:48 PM:
hey yur, I think if you read the article above fully it states the airframe is under 2kg and is not powered (as this is the next stage), therefore it was gliding so pretty light. It also says they have already test flown this design so it must be strong enough. The amazing thing here is the size at 1.5m and the fact they used no support material !? It is a VERY quick print for sub 24hrs to fly and there are no tools required as it says it 'clicks' together. The University of Southampton created a UAV from SLS process which took them weeks to print and required an engine - so in terms of creating a flying UAV quickly this is a significant step forward in designing FDM for manufacture. I wonder how many flights it can make without problems? Want to see more!
yru wrote at 3/11/2014 10:39:33 AM:
RepRap user have been doing it for years now :) question is, how light did they manage to print it and will it be strong enough.
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