Stage 2 Testing – First Powered Run

Stage 2 Testing – First Powered Run

One of the challenges of starting from where we are with this project is that we don’t have access to RAR’s conclusions about the final size, weight and power of his proposed full sized craft. And that’s important because for scale tests to be truly representative, the test model should be scaled for all three. But we do have some clues. There is some correspondence and we can of course use Crusader 1 as a reference point, even though (as we assume) C2 was designed to deliver even higher speeds than that.

The best of way of starting in this situation is the usual method used by science and technology. Gather whatever information and data you have and from that develop a hypothesis that could deliver your required outcome. Then test it. In this case, the test method is to run a powered version of the model already defined by RAR. Without knowing his conclusions we simply had to build it to those dimensions and then weigh it. We’d also made some assumptions about power output and of course we had a defined size from the model. Stage 1 testing proved that it floated – but would it plane? This is notoriously difficult for any new hydroplane design so we were pretty sure it wouldn’t at this stage. Further support for those thoughts came from the CFD images which when viewed from underneath show just how much of boat is below the surface at rest. But we had to test it to be sure.

With power applied and in conditions that were OK but not flat calm, the model ploughed through the water but wouldn’t get up on to the plane. In fact, it eventually shipped so much water it sank. This isn’t the disaster it sounds because the chosen lake was shallow and once retrieved only a couple of components were worse for wear after their submarine adventure.

Based on those test results, we have now revised the numbers in our original hypothesis defining weight, power and size and we move on to the next test stage. We believe that the model needs to be lighter, so to test that assumption, we’ll first add more power. We’ll also waterproof a few items and add a sealed inlet tract and spray diverter to stop it shipping water. Alongside that, we’ll also recheck some of the CFD images to see how the boat sits in the water based on current assumptions and plan to build a lighter hull. But one step at a time – onward.

See a short video of the engine running …