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Fun fly typical design


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Morning all,

 

Curious about the design of the fun fly planes.

 

Any good reads to that are specifically related to fun fly? Looking for a primers/intros to read and catch up with while I learn to fly this season. It also looks like a great way to rapidly hone developing basic flight skills.

 

I do already have a model aerodynamics book, but hoped there might already be a web article or two kicking around more focused on these unique machines!

 

 

 

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Not sure about where to go for good reads.

 

Fun fly recipe - lots of power, little weight, structural simplicity - aerodynamics take a back seat.

 

Pilot skill is very much prioritised over "fancy" airframes.

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Fun fly airframes are badly named, hooligan plane is better. As Nigel says above, but note little or no stability, and do stupid things at very short order. 
Not for beginners, as the reason they are simple to build is they get broken. 
 

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3 minutes ago, Nigel R said:

...aerodynamics take a back seat.

 

On that subject, sorry! 😂

 

I was interested to see asymetric rather than fully symetric wing sections. I would like to understand why there seems to be a preference for such short tail fin & rudder to wing spacing. So short that some have the horizontal tailplane and rudder set further back, with it being limited by downwash off the main wing.

 

Other than that I think you've largely answered my question thanks! What sort of power to weight ratios are they aiming for in the entry level class?

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1 minute ago, Don Fry said:

Not for beginners, as the reason they are simple to build is they get broken. 
 

 

In an earlier edit of this post post I did ask are they as they are because of trends and or being easy to rebuild, but scrubbed that just in case it came across wrong...

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11 minutes ago, DocPrinter said:

 

On that subject, sorry! 😂

 

I was interested to see asymetric rather than fully symetric wing sections. I would like to understand why there seems to be a preference for such short tail fin & rudder to wing spacing. So short that some have the horizontal tailplane and rudder set further back, with it being limited by downwash off the main wing.

 

Other than that I think you've largely answered my question thanks! What sort of power to weight ratios are they aiming for in the entry level class?

One of the events within the Fun Fly class is climb and glide. You have a fixed time duration of motor run and then the object is to glide as long as possible before landing. This is why more 'lifty' semi symmetrical wing sections are favoured. Also none of the events involve inverted flight so there is no real need for that symmetrical wing section.

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Posted (edited)

 One thing not yet mentioned is large control surfaces with big movement.

  My still serving Limbo dancer with OS 46 and mini pipe.

SAM_0475.JPG

Edited by J D 8
spelling
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I believe some have symetrical sections, thick wing sections, do they have short moment arms when compared to wingspans ? The extra wide chord makes it look that way, I agree. Large control areas, light built, low pitch props, extra diameter for pull rather than speed. Set up well the stall is pretty much non existant and liberties can be taken, lot of fun.

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33 minutes ago, Don Fry said:

Fun fly airframes are badly named, hooligan plane is better. As Nigel says above, but note little or no stability, and do stupid things at very short order. 
Not for beginners, as the reason they are simple to build is they get broken. 
 

With reduced power and reduced control movements they aren't that bad as trainers if using a buddy box.  I used  a Ripmax Dare-U, a very early funfly type model, as a trainer when I had nothing else airworthy for training and the beginners soon got the hang of it.  Because they can fly relatively slowly even raw beginners can keep up with them.  Mine had an OS25FSR.

148603076_RipMaxDare-U.thumb.jpg.c503b95be1626072042dd061b9fc8448.jpg

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1 minute ago, Robin Colbourne said:

With reduced power and reduced control movements they aren't that bad as trainers if using a buddy box.  I used  a Ripmax Dare-U, a very early funfly type model, as a trainer when I had nothing else airworthy for training and the beginners soon got the hang of it.  Because they can fly relatively slowly even raw beginners can keep up with them.  Mine had an OS25FSR.

148603076_RipMaxDare-U.thumb.jpg.c503b95be1626072042dd061b9fc8448.jpg

 

Agree, tone it down and it'll be o.k.

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5 minutes ago, john stones 1 - Moderator said:

...do they have short moment arms when compared to wingspans ? The extra wide chord makes it look that way, I agree.

 

Fair point. I was looking at a youtube video and hadn't really appreciated the lightness of the models. So I guess if anything exceptionally large chord for the weight and low aspect ratio with the horizontal tail plane/elevator as close as they dare to the main wing.

 

Screenshot_20240501_112126_YouTube.thumb.jpg.919fd0236bec58b51b07fb891e5cebf9.jpg

 

Screen shot from:

 

I do realise that is no where near a sensible starter model.

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Its interesting how that model in Docprinter's videos is going back to the original US-inspired funflys such as the Jerry Smith's Smith Special and Smith Super Special (below)with their monowheel undercarriages (well nearly in that case) and carbon tube fuselages.

902854465_SmithSuperSpecial.jpg.8bd3d1416106547b96576aaba3839b89.jpg

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With a low wing loading and reduced control movements, they make very good second models.  Against them is that they can lead to bad habits in approach management which can lead to difficulties when flying more heavily loaded models such as warbirds. 
 

An example was a friend who was frustrated by lack of progress - a number of his models suffered from his efforts until he bought a Limbo Dancer - all of a sudden, he had time to recover from situations which would have resulted in a stall or heavy landing and his confidence soon started to return. 
 

I do have some concerns over typical current trainers - often they behave like a de-tuned fun fly and it’s difficult to teach the nuances of approach control where coming in too fast/high can be rectified by rapid loss of energy with little inertia being carried.  The typical 5 foot .46 engined trainer of a few years ago was much better in this respect. 

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It depends what you want your trainer to train you on. Orientation and basic control, sure, flyweight foamie ticks the box. Heavier trainers also make you learn energy management.

 

Some funflys...

 

Another good example of the stick/boom type is 'Stickit IV'.

 

Stickit IV (oz7904) by Dan Stevens 1991 - plan thumbnail

 

plan / article availabile on outerzone:  https://outerzone.co.uk/plan_details.asp?ID=7904

 

 

And another 90s design, Fan Dancer:

 

Fan Dancer (oz15020) by Peter Miller 1991 - plan thumbnail

 

https://outerzone.co.uk/plan_details.asp?ID=15020

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Posted (edited)

I've got a XFly Glastar V2 ready to fly, but missed some perfect flying weather due to family birthdays and a break away! Will be starting soon. I appreciate that's a light weight and will follow it up fairly soon after with a balsa trainer that I've been repairing. I'm guessing my Fun Fly adventures will be hapening sometime after passing the A Cert. Which plane that's with depends how quickly I get the balsa plane sorted!

Edited by DocPrinter
Typo correction.
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4 hours ago, Don Fry said:

Fun fly airframes are badly named, hooligan plane is better. As Nigel says above, but note little or no stability, and do stupid things at very short order. 
Not for beginners, as the reason they are simple to build is they get broken. 
 

Not sure what you've flown but a good fun fly is far from unstable its quite the opposite manoeuvrability doesn't equate to instability, The Fusion fun fly is one of the best out there and has a ballistic climb rate, mega tight loops  and with up ailerons/ crow  can do insane dives with out gaining speed, glides superbly and is one of the best  planes ive flown and is very stable when treated aggressively so far ive never flown an unstable fun fly, I'm sure in your hands a Junior 60 is unstable😂

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More a case of neutral stability rather than positive stability from dihedral - lateral and longitudinal.  Your funfly tends to stay in the attitude it was put into, whereas a trainer style model will tend to recover to a level attitude if left alone.  An unstable model will diverge from level flight without constant corrections.

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26 minutes ago, Jason Channing said:

Not sure what you've flown but a good fun fly is far from unstable its quite the opposite manoeuvrability doesn't equate to instability, The Fusion fun fly is one of the best out there and has a ballistic climb rate, mega tight loops  and with up ailerons/ crow  can do insane dives with out gaining speed, glides superbly and is one of the best  planes ive flown and is very stable when treated aggressively so far ive never flown an unstable fun fly, I'm sure in your hands a Junior 60 is unstable😂

On the subject of a J60,  used to put the trani down to roll a fag, having got it lit, I pick the trani up, and corrected the direction of travel. I have been round the block. Are you sure you wish to chuck in the complications of crow breaks to a beginner. Or mega climb rates, which from memory suggests mega dive rates, and instantaneous acceleration.

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28 minutes ago, Don Fry said:

On the subject of a J60,  used to put the trani down to roll a fag, having got it lit, I pick the trani up, and corrected the direction of travel. I have been round the block. Are you sure you wish to chuck in the complications of crow breaks to a beginner. Or mega climb rates, which from memory suggests mega dive rates, and instantaneous acceleration.

dont k now, but my junior 60 does beautiful rolling circles, Not sure who the beginner is though. A fun fly as per the orignal post has these qualities

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49 minutes ago, Jason Channing said:

dont k now, but my junior 60 does beautiful rolling circles, Not sure who the beginner is though. A fun fly as per the orignal post has these qualities

From memory, I sold mine 30 years ago, but I remember the design was a machine without ailerons. A rolling circle would be difficult I think. The beginner is DocPrinter, who started the post. 

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