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Jan 13, 2017, 08:36 AM
Proud member of LISF and ESL
Quote:
Originally Posted by Gordysoar
Ed are you asking rehtorically or are you actually building a F3RES and planning on a contest.
I am tracking F3RES development this season, I have an article in RCSD this month on the topic. History here, Europe and Turkey.
Gordy
PS, pretty sure the F3RES rules are posted in the early part of this thread.
As it says in my post Gordy, I am not and have no plans to build an F3-RES plane at this time. Just learning about the class.
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Jan 13, 2017, 08:53 AM
Sagitta Fanboy
Quote:
Originally Posted by aeajr
Do the rules allow the length change?
No, they don't.

Rules are 15m rubber, 100m line, max extension 145m with 4Kg pull at 145m.
Jan 13, 2017, 08:58 AM
Registered User
John Lueke's Avatar
Actually the rules do allow a small change in length.

b) is started with a rubber rope consisting of 15 0.5 meter rubber hose and 100 meters nylon rope with a minimum diameter of 0.7 mm with a knotted into flags.
Jan 13, 2017, 09:19 AM
Proud member of LISF and ESL
Thanks John. So that Theraband Green cut to 14.5 m with 100 meters of line stretched to 145 M total might get you into something like 8.2 pounds of pull. Probably close enough.

From the brief read I have given the rules I don't see any max or min weight for the plane. What is considered a competitive weight for this class?

If we are talking 20 ounces, 1.25 pounds and have an 8 pound pull than you have a 6.4:1 pull to weight ratio. Not bad but not super powerful.

What are the launches like? Much in the way of a zoom?

Just starting to learn about this. Don't mean to distract the discussion. Just understanding the power to weight ratio for the launch.
Last edited by aeajr; Jan 13, 2017 at 09:32 AM.
Jan 13, 2017, 09:47 AM
Registered User
Competitive weight ballpark is 4-500g

Launches are in the 60-75m ballpark, with the short setup, the 10m red rubber from HK and 50 meters line.
Check post #14 for more setups, i.e. other rubber.
Jan 13, 2017, 09:58 AM
Proud member of LISF and ESL
Thanks for the info. About 16 ounces. Not much more than my Blaster 2 DLG which I think it about 12 oz.

So if you get an 8 pound pull on the high start you are at about an 8:1 ratio. Should be a spirited launch. I used to launch my GP Spirit at 7:1 and it would take off like a rocket. I could see the monokote flex.
Last edited by aeajr; Jan 13, 2017 at 10:09 AM.
Jan 13, 2017, 09:59 AM
Sagitta Fanboy
Quote:
Originally Posted by aeajr
Thanks John. So that Theraband Green cut to 14.5 m with 100 meters of line stretched to 145 M total might get you into something like 8.2 pounds of pull. Probably close enough.

From the brief read I have given the rules I don't see any max or min weight for the plane. What is considered a competitive weight for this class?

If we are talking 20 ounces, 1.25 pounds and have an 8 pound pull than you have a 6.4:1 pull to weight ratio. Not bad but not super powerful.

What are the launches like? Much in the way of a zoom?

Just starting to learn about this. Don't mean to distract the discussion. Just understanding the power to weight ratio for the launch.
The top ships come in under 15oz, older designs are up to around 18oz for the heavier ones (note design age is the main determining factor here, the earlier designs are heavier, with the oldest coming in around the 20-21oz weight that has been the standard lightweight 2m area prior to F3-RES developing. The recent designs are the lightest in general)
Jan 13, 2017, 11:45 AM
Registered User
Gordysoar's Avatar

Zagnut has it right


"the amount of pull isn't as important as the need for all the hi-starts to be equal in pull, 4kg at x distance is just the stated maximum to fit in with the simple model construction. best practice would be for the contest host to supply the needed number of identical hi-starts"


Since this is not a FAI regulated event, the high start spec is moot in an event if all the high starts supplied are the "same". The class isn't defined by launch height, so as in TD the launch is only there to get the tasks started.

The launch rubber is regulated so that there is uniformity in launches, not limits.

Of course you guys already figured that out on your own. (who says common sense is uncommon on RC Groups?)

Gordy
Jan 13, 2017, 12:20 PM
Team Horizon Pilot :)
I have green theraband and if you stretch it once reely well than 8 lb is exactly what it pulls . we use blue for our 2 meter events years ago and it pulls to 16
way to strong .
Gavin Trussell
So excited for this event
Latest blog entry: cr
Jan 13, 2017, 12:57 PM
Proud member of LISF and ESL
Time to pull out the Allegro Lite design and apply some modern materials to get the weight down. This is a winch proof wing. Don't need it to be that strong for this. I would bet a good builder could get it under 16 ounces.

Everything old is new again. 2 meter lives!
Last edited by aeajr; Jan 13, 2017 at 01:09 PM.
Jan 13, 2017, 01:57 PM
Sagitta Fanboy
Quote:
Originally Posted by Gordysoar
"the amount of pull isn't as important as the need for all the hi-starts to be equal in pull, 4kg at x distance is just the stated maximum to fit in with the simple model construction. best practice would be for the contest host to supply the needed number of identical hi-starts"


Since this is not a FAI regulated event, the high start spec is moot in an event if all the high starts supplied are the "same". The class isn't defined by launch height, so as in TD the launch is only there to get the tasks started.

The launch rubber is regulated so that there is uniformity in launches, not limits.

Of course you guys already figured that out on your own. (who says common sense is uncommon on RC Groups?)

Gordy
Actually, the histart spec does matter, because many of the designs are very optimized for the histart strength (these are NOT winchproof wings), particularly the lighter designs of the last couple years.

The regulation of launch strength is designed specifically to prevent the technology war that drove the move to molded designs in other disciplines. By restricting the histart strength, they created a situation where not only are the wing designs regulated by materials, but where those wing designs are actually close to ideal for the class.
Jan 13, 2017, 02:18 PM
Registered User
John Lueke's Avatar
I just did some testing with two pieces of green theraband. I tested them separately to see how much variation there was between them. Each piece was 31 ft long when I started. Stretched them to 1x and 2x and only got to 3.2 kg. Had to go to 2.5x to get 4kg. The problem was that after I stretched them to 2.5x they were now almost 18in longer with no stretch! So I don't know if they have some "break in" process then stabilize or if something else is going on. It was cold outside, but I kept them in the house until I was ready to stretch them.
Jan 13, 2017, 03:22 PM
Proud member of LISF and ESL
I have never used Theraband but I have seen latex completely lose its elasticity, when used below freezing, never to return. The rubber became brittle enough that when we pulled it it just failed to contract. Had to throw it out. I think it was a Dynaflite HD hi-start.

I typically will not put a HS out below freezing and usually not below 40 degrees. Either winch or electric under those conditions.
Jan 13, 2017, 05:54 PM
Flying = Falling (Slowly)
dharban's Avatar
Thread OP
The easiest way to comply with the rule is to simply purchase a conforming histart from someone like seta.tech.

A close equivalent (same pull, same energy) can be created from some other elastics as follows:

1. Lay out the tubing you plan to use and measure its length in meters with zero tension (L1).

2. Using a fishing scale stretch the elastic until the pull measured is 4 kg (8.8 lbs). Measure its stretched length in meters (L2).

3. Calculate the required effective length using the following equation:

Correct Length (meters) = (30 x L1) / (L2 - L1)

This length of the particular tubing will have the same pull and will impart approximately the same energy to the total launch system.

To the extent that an alternative elastic is heavier per unit of length of the elastic specified in the rules, two things will happen:

1. The alternative elastic will be longer than the "legal" elastic. This will require the monofilament length to be correspondingly reduced. i.e. if the calculated length of the alternative elastic comes out to 20 meters, the monofilament will have to be shortened by 5 meters.

2. Using a longer, heavier elastic in place of the specified elastic WILL reduce the performance of the system under some circumstances because the plane being launched will have to overcome the weight of a heavier system.

I am not recommending varying from the letter of the rule here. Only suggesting a way to possibly use an existing alternative to get a feel for how the rule is intended to work. The rule specifies both maximum pull and the amount of extension at which this pull is realized. For any given PIECE of elastic, its pull will be defined APPROXIMATELY by the equation;

Force = k * x

Where k is the elastic coefficient (fixed for any particular length of any particular elastic.) and x is the amount of extension.

Energy = 1/2 * k * (x ^ 2)


I hope this will be useful.

Happy Landings,

Don
Last edited by dharban; Jan 13, 2017 at 06:03 PM.
Jan 13, 2017, 06:03 PM
The King Moonracer of balsa.
Windependence's Avatar
Hi Don, you have a PM.


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