Xtreme 3D - My 62nd Model

Looking-back to my previous 'BalsaCraft Xtreme 3D' (my 40th model) as the best-flying plane I've ever flown - I just had to have another one

But the kit was no-longer in production, so after several months of searching I eventually bought an un-started kit via the BMFA website . . . but would it now live-up to my high expectations?

The Winter build went well and the model was first test-flown on Monday 6th April, 2009:

The first test-flight showed that the engine thrust-line needed adjusting and also that a pair of stronger aileron push-rods were required

The second flying session was much better, with the engine thrust-line perfect and the aileron push-rods resisting in-flight bending

After the second flight I toned-down the aileron and elevator deflections a little, and then began the third test-flight (on Wednesday 22 April, 2009), which unfortunately ended a little less than perfectly:

What are the odds of an out-of-control model plane flying 'knife-edge' between the top two strands of a barbed wire fence without the fuz making contact with either of the two strands of barbed wire - until it reached a point approximately half-way between the rear of the canopy and leading edge of the tail-group!

The barbed wire cut-off both wings, severed both aileron servo leads, and severed the rear-end of the fuz (leaving it sort-of attached only by the elevator 'snake.' The 'really good thing' about this crash(!) was that the engine didn't make contact with the ground, so it was completely un-damaged

At the time I had no idea what had caused the complete loss of radio control. The radio was working perfectly before and after the crash, so I began to wonder if outside interference was responsible. Interestingly my first BalsaCraft Xtreme was damaged during it's third test-flight too:

(having noticed this I guess I'll need to be extra careful during my current Xtreme's 159th flight!)

Subsequent bench-tests showed that the radio would 'cut-out' if I lightly tapped the Rx with my fingers - but is this the 'cause' or the 'effect' of the crash? I replaced the Rx Xtal and the fault 'went away.' So, providing the radio passes its range-test, I will continue using the same radio gear

Range-tests followed by further test-flights confirmed that the faulty Rx Xtal had caused the model's crash. The model was now flying better than ever following its re-build and it was now time to cut the engine cowl to size and fit it. First the fuel valve and remote glow-plug socket were fitted and then the cowling was removed from its packing and offered-up to the engine - and this is where I discovered the next problem . . .

The Saito 100 was going to stick too far out of the front of the cowl! Of course this is my own fault for not checking things over before starting to build. Had I noticed this problem at that time I could have so easily extended the front of the fuz to compensate. But why didn't I do the normal checks before starting to build? Because I'd built one of these kits previously and I knew that the cowl fitted ok I suppose - but now that I can see the problem I realise that I'd used a much smaller K&B .48 engine on the first model. Dratt!

I decided to extend the front of the cowling and the next pic shows the difference between the stock cowl and my modified one:

The next pix shows how my longer cowl will cover the engine - but of course it's still in it's first primer coat here. I think the new shape's looking good:

And finally, this is the modified cowl complete. I actually think it looks better than the original:

Of course the modified cowl weighs a little more than the original, but this has been compensated for by removing a little of the nose-weight which was attached to the firewall. All-in-all a reasonable outcome I think