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F5-RES Rules discussion


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From the rules that we have produced and with Anthony's help, this is my interpretation of what is permitted. Is that correct?

 

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John Minchell

Like the rules clarification - and another vote for F5RES - to keep it inline with the F3RES.

John M

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I am having a little difficulty with construction – use of carbon.

It says spars and leading edge can be carbon – there is no mention of the trailing edge (it is almost a spar).

I can also understand there are no Carbon D-boxes over either balsa or foam...... You get to the very expensive F3K constructions. A few strips of carbon are allowed on the fuz, but what about little strips of (straight) carbon over the edge of the ribs ?

In other words construction as in attached photo. (which any competent builder could do)

Elevator.JPG

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It's as it says Anthony. The rule is a wooden airframe with the permissable exceptions of carbon LE and spars. TE needs to be wood. 

It makes it difficult to build wings with very thin trailing edge segments and keep them usable.  Makes an interesting challenge. Ony. Last F3-RES, I added a second carbon spar in about 30mm in front of the spruce TW which seems to have worked OK so far

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In that it's a spanwise member the TE could be considered a spar - needs clarification.  Rib caps aren't mentioned in the CFC allowed list so I assume they are not allowed.

I note that Boron Fibre Composite is not prohibited.  Plywood is a composite material but at least it's made with wood - except 'liteply' - I think that's old cereal boxes.

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I would consider a trailing edge as a spar, in that it stops the trailing edge from going wigly. You will note in the photo that there is no carbon on the front, because I removed a tiny bit and put it on the back, so in that structure there is less carbon than allowed.

Then there is ultra-high molecular weight polyethylene used for living hinges - some class that as a composite.

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Response from Holland

 

Hi Martin,
Only the LE, Spar and wingjoiners can be made of something else than wood. For example GFK/CFK.

So the TE must be made from wood and cap strips are not allowed.
Also 1/3 of the fuselage must from wood (frontpart) the boom can be made from carbon.

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Martyn, sorry (or not) for "picking," it is far better to have a set of rules that have been heavily debated and clarified, than a set of flimsy rules that can constantly be abused - which would then cause discontent.

One last one, the spoilers on my Ava are made of carbon, they are rigid and thin. When closed they are a perfect fit, and will not warp. I don't like spoilers, but prefer flaps (for braking)........ But the rules are the rules.  I have tried just balsa ones, but in the end put a layer of very thin glass on both sides and they are far better.  Do I presume these can (also) only be made of wood. Bear in mind I could make a good case that they were part of the spar system and became seperated when I cut them out.

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Graham Lorimer

Anthony

You refer to your AVA and the make up of Spoiler etc, is this a model that would comply with F5RES?

Mine is a 4 meter wingspan and fiberglass / carbon fuselage, I thought these would be ruled out based on size and materials used.

Looking forward to your reply, I hope it will clarify a few issues for me.

 

Graham

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28 minutes ago, Graham Lorimer said:

Anthony

You refer to your AVA and the make up of Spoiler etc, is this a model that would comply with F5RES?

Mine is a 4 meter wingspan and fiberglass / carbon fuselage, I thought these would be ruled out based on size and materials used.

Looking forward to your reply, I hope it will clarify a few issues for me.

 

Graham

I don't know if an Ava style spoiler is compliant, so I asked.  Obviously an Ava is nowhere near F5RES spec. The reason I ask is that it works perfectly -"the carbon fibre moving bit"   Just about everyone that flies a glider has seen an Ava - hence it makes a good reference point.

I have (out of lazyness) made spoilers just from balsa, and not been happy with them - unless a perfect fit, they will act as spoilers before they are deployed, as spoilers.

I do have some nice 3mm balsa that would do though - see photo.

Spar.JPG

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Graham Lorimer

OK Understood

 

My AVA has enlarged Spoilers made from Sheet carbon fibre, they tuck away nicely but work very very well when deployed.

 

Graham

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3 hours ago, AnthonyB said:

I do have some nice 3mm balsa that would do though - see photo.

 Sadly, the reinforcement will have little effect structurally, placed half-way through the thickness - it's on the neutral axis.

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 Moving backwards slightly.

I have been pointed in the direction of the USA 2019 provisional rules derived from the amended 2019 German rules.  (It doesn't get more confusing I hope). I have had a read through and it clarifies some (many) of the points that have been raised above including one that has been raised privately regarding spoilers. I have renamed the file with a (USA) suffix but with the exception of section 10 which is directly related to the USA, I think that I will rework this again for F5-RES.  It should be a simple task, it is far clearer than my own initial attempt.

It doesn't specifically address the issue of carbon rib caps but interestingly does include carbon spar caps which I built into my first F3-RES. It also doesn't address  specifically CF TE as a spar but as a CF LE is specifically included, I believe that we can assume - especially with confirmation from our Dutch friends -  that the TE section should be wooden.

It does specify in much greater clarity the location of the start line (position) and landing markers which is a bonus.

 

Attached...

2019 English F3RES Rules Set Draft (USA).pdf

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I have now revised the document for a UK F5RES but have a couple of questions. There are some typo and reference errors in the USA document but its not too bad. Could be easily anglicised, the German roots are still showing.

 

My questions relate to

2.3.3 . I need better words to described the radius of the pointy bit of a spinner

5.3 I don't understand how this would work if a pilot is moved to a different group. How would his aggregated score be dealt with?

9.5 I don't understand how the number of fly off qualifiers could be calculated in advanced unless it was simply one (or two etc). from each preliminary round group.

 

Attached...

 

2020 English F5RES Rules Set Draft v0.4 Draft.pdf

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2.3.3 Radius of extreme nose or spinner is checked with a template.  The 7.5mm F3B one is used as an example throughout the FAI soaring rule book.  A 5mm radius version is used in F3K.  Here's the F3B rule.....

77964D2D-91F1-4B89-9C62-D53C9221995A.thumb.png.377b37fd036fe88d380d9c4b7d9bc624.png

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5.3.  This is standard practice in the F3K rules and probably other classes - I would need to check.

The pilot(s) getting a reflight in a round, fly in a new group composed of the reflght pilots and made up to a full group with pilots chosen at random from the rest of the competitors.  A pilot selected at random can decline to fly.  The reflight pilots get the score they achieve on the reflight.  The random pilots get the better of their existing round score and their reflight score.

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9.5

You don't have to have a flyoff.  The number of flyoff competitors is not calculated, it is the CD's choice and they must be announce the existence of any flyoff and the number of competitors involved before the contest starts.  Here it is mandated to be between 4 and 8.  (Other class rules may have guidance like a certain percentage of the competitors.)

In Free Flight, only competitor tied with a perfect score at the end of the prelims go on to a flyoff.  The  RC glider concept of the top 'n' competitors starting a new contest the end of the first one seems odd.  You could win the prelims and come last in the flyoff?  Your prelim position means nothing once a flyoff starts.

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This part nails the carbon..

A model must be predominately wood construction. The following methods are allowed:

2.2.1. Open ribbed wing surface, solid wood surface, “D-box” wood surface, or a combination of solid wood and ribs.

It's the “wood surface” that does it (other than leading edge).

This set of rules is elegant.

You start with the start line (8m apart) – facing into wind.

The landing points are 10m down wind, which is reasonable. (8m apart).

At the end you turn round and face the landing point. You are now 10m (33ft) away from were you want to land – Too far for me and most I have observed.

A line written  “The contestant may approach to within 2m (or 3m) of the line of landing points, but no closer until the round has ended.” This would keep everyone back from the landing area until everyone has landed. There is a safety aspect to this. (the original 10m is far safer – but I (and others) like to be closer)

It was the continental use of 2m that complicated it all.

I was told (long ago) - Spread your fingers and the curve, where they meet your hand is minimum curvature. A 1p coin is 20mm diameter (10mm radius) and so 5mm radius is very small - I would prefer to be hit by a 20mm radius nose if you are going to hit me. Domed nuts are allowed at 5mm - again too small.

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17 hours ago, mikef said:

 Sadly, the reinforcement will have little effect structurally, placed half-way through the thickness - it's on the neutral axis.

You are right about structural strength. I placed a 1lb weight 9 inch from a fulcrum and there is a notable bend. Oh, wait 1lb is 454g or the weight of a full model. Perhaps the lower surface (below carbon) is under compression and the one above under tension. The only reason for that, would be to have a "wood" surface. Given a layer of profilm it would go un-noticed. Now try with a straight sheet of very light plain balsa.

PoundW.JPG

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