Welcome to the website of CleanEra, a group of innovators in the field of aerospace engineering from Delft University of Technology. CleanEra pursues its dream of creating a green future for aviation. This dream is made reality by using contemporary designs to build a family of sustainable aircraft, the Zeft family. The first family-member to demonstrate CleanEra’s inventive technology, will be a UAV demonstrator called Zesar.

Finishing the bottom of the windtunnel wings

The bottom part of the wings are finished, the upper part is next. If that is done, the wings itself are finished and the ailerons can be fitted in when they are done. After the wings are made, the workshop will begin to make the centerbody of the windtunnel model. We expect that the windtunnel model will be ready within a month or 2.

img_1529 img_1530 img_1533 img_1535

Interview with DEMO Magazine

In February, the editorial office of DEMO Magazine contacted us if we were interested in an interview. Their idea was to show people from the university just how these projects work, where people with a lot of theoretical knowledge work together with people from DEMO to get their ideas become reality. So their question was how we made our project work and get our windtunnelmodel manufactured by the people from DEMO, and what their role in the design phase was, with adjustments of drawings and advice on machinery and feasibility of concepts. The interview was taken with Peter and Ed from the DEMO team, and Remco and Pjotr from ZEFT. The interview can be found as an internet article or in hardcopy at DEMO workshops DEMO at the university.

Propeller blade production

Today, Remco and Pjotr started production of the first propeller blade, under supervision of François. As a try-out, we want to use carbon fibres in the aluminum molds and later inject them with resin. So the first objective is to get the chopped carbon fibres into the mold, through the small cavities. We decided to cut the fibres into pieces with a length of about 1cm and then use a vacuum pump to suck the fibres in. However, this idea turned out to be unfeasable in practice, hence we tried to blow them through the mold. After inserting several small doses of fibres and blowing them through at 4 bar, the result was not really satisfying. As can be seen in the pictures, some of the fibres got to the outlet of the mold, but most of them clustered together and blocked the way for the rest. In other words, the method with the carbon fibres is not satisfying.

After the failed attempts with carbon fibres, we chose to try producing a blade using metal fibres. These fibres were cut into even smaller parts as used before, having lengths of only 1 to 3mm. Now using the pressurized air to blow these fibres into the mold should give us a mold nicely filled with fibres closely packed together. Only a few fibres at a time were inserted at the inlet using a pincette, as shown in the pictures. In this way, 1 cubical centimeter of fibres was to be put in the inlet manually. However, after the resin was flown through and had hardened out, the blade contained very few fibres and surprisingly a lot of air.

Conclusion from this first production attempt is that close attention should be paid to the airtightness of the mold via testing before injecting resin, and that we should think of another method to get the fibres stacked together in the mold. Some pictures of our first attempts are shown below.

img_1384 img_1398 img_1395 img_1391
img_1401 img_1414 img_1424 img_1410

Windtunnel model manufacturing process

Production of the windtunnel model is continuing steadily in the workshop, during the manufacturing process the DEMO team made some nice shots of the milling process. During milling, the millinghead gets fairly hot, hence water cooling is used to maintain an acceptable temperature of the tool.

One of the movies showing both milling and cooling is shown after the break, it gives a fine impression of how the windtunnel model is being realized, step by step. (more…)

Winglets and aileron hinge production

The workshop at Aerospace Engineering has started work on the winglets. The winglets are about 12 cm high and very thin, making it a difficult part to manufacture. Also the aileron hinges are almost finished and are test fitted into the wings.

img_1297 img_1298 img_1291 img_1289

Aerodynamic design

We are hitting the 6 month marker by now. It seems like a long time, but it has actually flown almost as fast as our aircraft will. Much has changed in the aerodynamic design of the Zesar since the preliminary design. The use of a NACA airfoil has changed to multiple airfoils which we optimized for our flight conditions and also the planform has been further optimised. The optimisation process included models of 3D full potential flow combined with 2D viscous simulations to get reliable results. With the windtunnelmodel manufacturing going along steadily we are all very excited for the windtunneltest where we will find out how close our predictions come to reality!

Although the aerodynamic design took a lot of time, we made our models parametric which means that changes can be applied through the design very quickly. This can be changes in either planform, airfoils or size. This will make the design of the next CleanEra aircraft even more efficient since repetitive work required by the engineer is kept to a minimum. An example of the models we use is shown here, it is a full potential flow simulation of the aircraft using VSAERO.

CFD analysis of the Zesar aircraft

Windtunnel model wing progress

The production of the wings for the windtunnel model is well underway, the crude form of the wings can now be seen. Although the team from DEMO have made much progress, it will take them another month to finish both wings.

Here are some photos to give an impression of how the wings are being manufactured.

img_1195 img_1206 img_1240 img_1244
img_1250 img_1258 img_1260 img_1177

First propeller mold

The team from DEMO have finished production of the first propeller mold!

An aluminum mold consisting of a top and bottom part of the propeller blades of the first propeller has been finalized. The propeller blades will be made of composite material. Next step in the production process is trying to create the blades using chopped fibers. This process is planned to be started next week. When this production process does not give the required results, the blades will be created using the lay-up of fibers and injection of the mold with resin.

Because the Zesar will make use of counter-rotating propellers, another mold has to be created which is mirrored to the one already produced. The drawings for this mold will be directed to the workshop this week.

imag0174 imag0175 imag0176 imag0178
imag0179 imag0180 imag0182 imag0183

Manufacturing of the windtunnel model

The employees at the workshop started with the production of the windtunnel model this month. The workshop is part of the DEMO company, Dienst Elektronische en Mechanische Ontwikkeling (Service for Electronic and Mechanic Development). DEMO is stationed in a number of faculties of the Technical University of Delft, including the one of Aerospace Engineering.

The windtunnel model is going to be constructed out of solid aluminum. The aluminum blocks required by the workshop are sponsored by Corus. This company generally deals with steel, but they also have a well developed aluminum sector. The sponsored blocks are therefore of high quality aluminum and weigh over 350 kg in total. The employees of DEMO require about 6 months to mill around 90 procent off of the material to end up with the windtunnel model.

img_1132 img_1134 img_1137 img_1143
img_1148 img_1149 img_1154 img_1155
img_1162 img_1164 img_1168 img_1175