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Frazer Nash FN5 gun-turrets


Fidd88
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Crikey, my thanks, that's just made my day! It's nothing most people couldn't do. I taught myself to use Fusion 360 CAD early on, which allowed me to send .stl files to 3dprintuk, who then sent the "bits" back in the post. I then discovered that SLS Nylon, was both dimensionally very accurate, and crucially, could be tapped with threads down to M1 threads, allowing sub-assemblies to be screwed together, rather than glued. This has two benefits, it allowed for more efficient "nesting" of parts, which reduced the cost of printing larger parts, but it also allowed for the reversal of assembly if I got into a jam with the build sequence. This turned out to be vital, as in effect, it was akin to building a real turret, but with "4 foot long" screw-drivers, so tool access was a major consideration in the sequence of the build.

Other than that, building them was fairly straight-forwards, other than making the compound-curved perspex panels for the cupola, to get the true shape of it. The other related problem was learning to draw compound curves in CAD, which was tricky. This meant that certain features such as the chordal brace stiffeners and the ammo feed-chutes were repeatedly drawn until they were got right. I never really managed it with the chordal brace stiffeners - the green structure that goes from the arch to the top of the main supporting silver side-piece of the turret.

Fusion 360 can still be downloaded and learned for free, although with some functionality unavailable. Have a go! It takes around 2 months of practice and working through tutorials to get quick and accurate with it, and maybe another two months to really master compound curves. There's a very helpful set of forums if something defeats you...

If there's anything you want to know more about, just sing out. My Youtube channel which has multiple films documenting the build can be found by searching YT for "Fidd88". I fear I'm no David Lean, and some are pretty dull, being made more to remind me than for public consumption, but some are interesting.

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Hi all,

Lots of recent practice flying my little foam E-flite "Apprentice" - basically a Cessna 150/172 style high-wing monoplane, but with no operable flaps, undercart or variable-pitch prop. It has a wing-span of around 5 feet, and all the modern bells and whistles in the form of gyros, "panic buttons" and so forth that make learning so much easier these days. I've been flying 2-3 times a week, and can fly and land it even in strong gusty wind conditions without breaking anything although once in a while I have to throw an approach away rather than trying to rescue an approach that's gone pear-shaped. This is mainly because the landing patch is only half the size of a tennis-court, with high uncut grass of 3+ feet all around, so "landing long" just isn't an option. It's not unusual to hear a little whisper as the wings ever so lightly brush the tops of the high grass in the undershoot!

Now that I've cracked landings, both into and cross-wind, I'm now conducting low and slow manouevering flights to really work on rudder and aileron coordination and accurate trimming before I start to look around for more complex model. At the moment I'm getting 10-12 minutes a flight, and reckon I should manage 14 minutes before the battery gets to 50%, if I don't hammer the throttle too much.

Brilliant fun, but I need to get back in the workshop!

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  • 2 months later...

Hi all,

The last few weeks have been busy on the RC flying side. I've done over 100 hours on the "Apprentice" with only one crash. I'd been getting more confident and doing aerobatics, and forgot to switch the control-defelection from high-rate to low rate before landing, which would give fine control instead of the rapid inputs required for aeros. I'd made a pig's ear of the approach and so went around in the normal way, however because of the rate still being high, the aircraft went suddenly vertical at about 15 feet, before executing a very pretty power-on spin-entry - and then ploughing into the ground. The engine-mount, fuselage and tail all suffered damage.

After a couple of weeks I've replaced and repaired all the damage, and should be ready to re-maiden it tomorrow. I've also been building a Dynam Hawker Hurricane, which has flaps, retractable undercart, and should presently be able to carry a gimble mounted FPV camera. I'm getting some stencils made to paint all the roundels, (rather that using the stickers) and will be converting the insignia and letters to that of a 303 Sqn example. I've also added yellow prop tips to the 3 bladed prop, and will add "oil-leaks" and other weathering. Pics to follow in due course.

Hur4.thumb.jpg.a11c5bcc4995f1268d8056d982ab80e5.jpg

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  • 5 weeks later...

Yes, I'm a member of the BMFA for my regular RX flying, but also of the LMA as the Wellington project is a much bigger airframe than they deal with, so I'm also a member of the LMA for design scrutineering for that project. We had a phenomenally busy Club Night here, with some 20 pilots turning up for flying - likely one of the last Wed Evenings that'll be flyable until the other side of Winter now, so everyone was having a last flit. I'll still be flying on the weekends, MET permitting.

I need to get on with getting the Hurricane airworthy now, and start learning about FPV flight once I've got the measure of LOS (line of sight) flying the model in the normal way.

This evening I drew up the proper exhaust stacks for the Hurricane - Dynam supplied me with ones for a later marque of Hurricane/Spitfire with the 6 stacks a side, rather than 3 (doubled) with the "fish-tail" end section. Not easy to draw. Pics to follow when printed and fitted. I need to buy a new TX, and a Crossfire unit for extended range, which should make the control connection to the TX bomb-proof at the ranges I'll be flying. It also bumps the video reception range to well over 4km without drop-outs. Being Digital video it lacks the extreme range of the older analogue jobs, but it's not legal to fly FPV beyond line of sight in this country, so much more than 1km isn't needed for this size of model. So my possibly erroneous understanding has established. Probably!

By the by, I came across an very interesting youtube channel of a Texan model-maker, working in metal, who is currently producing a series of model metal-working machines - lathes etc. Amazing stuff, as it all works! I'd love to gave a small watch-maker's lathe/mill but there's no way I can afford it as well as other tools and materials I know I need for the Wellington.

See: 

 

 

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