Thunder Tiger 40L

[John Muir]

I've just been reading Alex Whittaker's review of this model in the September issue. Very enjoyable read and I like the overall approach and the fact that he's very honest about his opinions of the structure/ potential ease of repair and so on. He has some minor criticisms of the model's handling however, including needing a lot of down elevator when inverted, difficulty getting it to roll nicely and a reluctance to flare on landing.

Now is it just me, or is he not just describing a nose-heavy model. He did fit an OS 46AX which weighs well over 500g when the recommended engines only weigh 465g (TT46PRO) and 357g (TT GP42) and the model does have quite a long nose, so adding up to an extra 200g (8oz) to the front would make a difference. I'd be willing to bet the model was designed around the GP42 as it's supposed to be a trainer and all his observed flaws would magically disappear if he fitted one of these.

Now I'm sure Alex balanced the model before flying, but in my experience kit CGs are often specified too far forward to give 'safe' handling. I wonder if moving the CG back would show this model up in a better light. Might even knife edge better, although I can't see that it would have been designed with knife edging in mind anyway.

I don't have one of these and I've nothing to do with TT, but I just feel that giving the impression that the model has faults (albeit slight) which are really due to choices made by the reviewer isn't entirely fair.

[David Ashby - Moderator]

Thanks John, good points, I'll ask Alex to drop by.

[Alex Whittaker]

David has asked me to reply to your post. There's great merit in your views, John. You certainly could be right. Exactly such thoughts did occur to both Nathan and me as we discussed the model. As you might guess, I did not rush to judgement, but nor would I like to be accused of missing anything. All models are a compromise, and in my experience, few models are flown with the Manufacturer's own brand engines, and many modellers use more powerful engines. I'm not if sure the difference between a TT .46 and an OS .46 is half a pound, since I haven't weighed both engines. I was trying to analyse why I felt that I was not completely satisfied with what is essentially, a simple airframe. I have similar "first low winger" models (well overpowered!) in my shed that frankly have better all round performance. I don't think the TT model possesses anything like a serious flaw. It's a remains a nifty model at a smashing price, I bought the model with my own money, and I rated it highly, but I did wish to acquaint readers with some of the impressions that flying it had raised. Overall, it is a great model for the dosh, and many experienced modellers will fly it as a sports model. If it was one of my overweight home-brew designs, I'd just increase the rudder and elevator volumes. Thanks for the analysis. Speaking as a scribbler, it's nice to be read so closely!

Alex 

[John Muir]

Hi Alex, I must say this is impressive, getting an immediate response from the writer of the review himself! These fora (forums?) really are amazing.
I was just curious as to where the centre of gravity had actually come out on the model, especially relative to the instructions, and if you had tried moving it back. Obviously, you can't do everything in the time available before you publish, and I'm sure I'm like everyone else and wouldn't expect every tiny nuance of the model's handling to be examined in detail, but as it's your own plane, I did wonder if anything had come to light since the review went in, especially as we now have this section on the forum where follow up information could be circulated.
My feeling is that a lot of people who buy this model will use a GP42 or an OS 46LA and it might just be the case that the model performs better with these lighter engines up front and it would be nice to know.
Incidentally, I don't know the exact weight of a 46AX either, but most ball raced engines of this size come in at around 520-530g including silencer. The GP42 is 357g with its silencer, so the difference is at least 160g (about 6oz?), so ok not half a pound, but still quite a lot. The 46PRO is light for its class at 465g, so it's in between. The 46PRO is a first class engine, by the way.
And yes, I've been a subscriber since the seventies, and I read the whole magazine every month, even reviews for models I have no interest in buying. I may be slightly sad, but I bet Mr Ashby likes me.
Thanks for the response gents.