Balsa Wood Hurricane – the first test flight

As you may have guessed from the fact that the title refers to the ‘first test flight’, it wasn’t wonderfully successful.

 

As you see from the video, the plane quickly veers to the left, flips on its back and drops like a stone.

One  potential issue is with the weight. The flightpath suggests that the centre of gravity is too far back, but the problem could be that the nose is too light rather than the tail too heavy. However, all the talk on the balsa modelling forums I have skimmed is about keeping the model as light as possible. Clearly more reading and experimentation is needed. As a result, you may see my Book Diary dominated by volumes on free flight aerodynamics and the like over the next month or two.

Further examination of the model post-test flight revealed that the whole tail section was slightly twisted, which almost certainly contributed to the model flipping as it flew. I think this problem may have its roots in the original construction rather than crash damage. Therefore, the plane may well be doomed from the outset, and I will have to consider the implications before getting too far with the next flying model. Before that though, I will repair this one (the undercarriage took a bit of a battering and needs re-glueing), and try to adjust the tail surfaces to compensate for both the natural tendency to diverge from straight-and-level flight caused by the rotational effect of the propeller and my shoddy workmanship.

The only possible factor which could have led to such a disappointing first flight which is outside of my control would be the wind. As you can see in the video, it’s a moderately breezy day. Perhaps I should have waited for a calmer period. I also launched into the wind (as much as I could – it was swirling a little in the enclosed garden) which should give the plane more lift. The lightness of the plane, combined with the wrong centre of gravity could have contributed to it gaining the lift too quickly and flipping over as it did.

All in all, a sobering experience, but one which has made me more determined to get it right in future. I suspect my repairs will be somewhat in vain and this model will end up on display only, but even if that is the case, I have learned important lessons from it.

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3 thoughts on “Balsa Wood Hurricane – the first test flight

  1. When you built it I didn’t even realise it was supposed to be able to fly.

    One of hobbies where you will pit yourself against a number of failed attempts, but when you nail it, it will feel glorious?

    • This will feel glorious when I eventually get it right. I think it could take some time and several models, lots of minor repairs and quite a bit of background reading, but rather than begrudge that, I am really looking forward to the process.

      Here’s an example (though not amazingly clear) of what should happen eventually:

      I believe that is an exceptional flight though, as it lasts about 40s. The general consensus as far as I can tell is that something in the region of 20s is pretty good, and if it lands neatly you’re doing well.

  2. As a very late addition to this blog post, here’s an interesting comment I found on the Guillow’s Forum:

    “I’ve never built the 500 series Hurricane kit before, but there have been several good looking ones lately, and when James built one I thought that I might as well, so I stopped by a local hobby shop and bought one. When I got it home I opened the kit, weighed the wood and looked at the plans. Now I understand why everyone who builds one seems to have trouble getting a model with good wing area and an ample tail surface to fly. In proportional terms, this thing has more lumber aft of the C.G. than any other kit I have seen. I’m not sure that even a lifting tail will get this one flying i built according to the plans.

    This one is 2005 production and the wood is so-so. The sheets with the wing parts are very good, each weighs 3 grams, but the sheets with the fuselage formers are 8 grams each. That’s about 17 to 18 pound wood. For this one to fly, without 10 grams of BB shot in the nose, the structure has to be reduced aft of the C.G. and built with contest grade (4-5 pound) wood. Even then, it may need the lifting tail.

    Compounding this is the tiny nose. Hurricanes were a little short coupled in the front, and had very pointy noses. At this scale, there is almost no room for a sturdy under structure to support thrust adjustments”

    This was written by someone who has designed some of the newer kits for Guillow’s, so knows what they’re talking about. It sounds a little like I started off with one of the most challenging models available!

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