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2m f3a plane. Lexicon.


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Hi guys, thought i'd do a bit of a build thread on here of my latest f3a plane. I have posted else where so apologies if you have seen some of these pics before.

I started drawing this up on cad last summer with intention of using it this season, its finished and hopefully we'll get some comps later in the year.

Its a 2m f3a model, powered by a 10s, single drive, geared down (belt driven) electric motor. Some more unusual points being it has an all moving tailplane and a swept back wing.

Heres some pics!20191221_152357.jpg

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Wow. That is some CAD work Dan. I like the fuselage split at the low level, easy to build up straight from the bench.

Does the very sharp taper and sweep back lead to any handling oddities?

Saw your funfly model in the BMFA news too, any chance of some details on it in a separate thread - looked quite an unusual approach to the contest.

Edited By Nigel R on 01/04/2020 10:41:30

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Its an all moving tail so the tail will just sit where it needs to. The wing is set to 0° incidence, as is the thrust line. (2.5° of side thrust). I trim the model for a hands of vertical down line and adjust the up/down thrust in an upline for hands off. This means i'll hold in a bit of up for upright straight and level and a bit of down for inverted. I do this because generaly you will use less mixes and it feels the same whether up right or inverted.

I use cyano to glue all the frame up then mostly aliphatic for all the sheeting.

The swept wing and taper works great, no strange tendancies at all and looks great in the air.

When i build my next funfly i'll do a thread on here

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Hi Barrie, how are you?

I use turbocad, bought it off ebay years ago for about 15 quid, works fine for what i need.

Its sheeted in 3/32 all over. Good compromise between weight and strength. Theres about 70 sheets in total so weight selection is important. Its covered in all white easycote, then im going to spray some kind of design over that.

Dan

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Photos usually get rotated, when uploaded, if you have rotated your 'phone to take them. To avoid them rotating, edit them before uploading, by edit I just mean a simple edit that allows you to save them. They will then upload correctly.

Great work as usual Dan.

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The transition from turtle deck to fin is always a bit tricky, i learnt this method off another build thread on the gbrcaa website.

The first pic shows 9x 1/4" laminates cut to the profile of the leading edge of the fin. These are then carved to shape you need, taken off then hollowed out with a dremel. Came out about 30g

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kc, forgive me if I'm teaching you to suck eggs! Dan's design is based on one used by the current world champion and there are others that have even larger fuselages. What these designs are all seeking to do is to provide as good a performance in knife edge as the FAI F schedule contains a large number of knife edge and compound manoeuvres. The amount of fuselage side area helps greatly when you are performing KE loops or horizontal circles. The other issue is drag and today's aircraft are flown at as near a constant speed as possible whether climbing, diving or flying straight and level. Drag in the downline is also complemented by prop braking either from the ESC/motor or from an IC engine idling.

I can't find a way of attaching a document so I will leave you with a link to the FAI Sporting Code. Go to page 26 for the description of the manoeuvres in F21 and to page 35 for an Aresti diagram of the schedule.

I hope that will answer your question as to why a bulky fuselage is needed in modern F3A aerobatics.

Of course, there is also the matter of fashion. Some pilots love canalysers, others don't. If the world champion is using some aerodynamic tweak then everyone else will also want what ever advantage there is to be gained from the design. At the end of the day though, it is down to the amount of practice the pilot puts in and the ability to perform at your best when under pressure.

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Peter, maybe it's mostly a fashion thing? Perhaps if a top pilot comes out with a stick fuselage or a profile one or just a scale like one and then wins everyone will follow suit! As just a bystander ( = club/sport flyer ) competition aerobatics appears to have gone to extremes now. Everything seemed a lot more sensible when a Loaded Dice or a Graphik were a suitable thing to have for aerobatics. Planes should look realistic perhaps?

Having said that the construction of this current model is magnificent and good to see someone designing and building for himself rather than buying fancy foreign planes.

Edited By kc on 07/04/2020 11:01:06

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You can't do knife edge loops - easily - without a large fuselage and big rudder, so I'd say not a fashion thing, in general. The exact shape, as in how to distribute that large side area, possibly a bit of fashion.

Loaded Dice? It was what was needed for the schedule of the day.

Competition planes will look as realistic as they need to given the rule set.

If you want "realistic" aerobatics, IMAC is the competition for you, it has a scale rule.

If you want aerobatics with a Loaded Dice, there's the retro aerobatics guys.

Your last point, absolutely.

However, I'd qualify that with the fact that most competing pilots are pilots foremost and less worried about building than they are flying and winning. If you have limited time available then practice is where you would spend it.

Edited By Nigel R on 07/04/2020 11:07:16

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