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Apr 01, 2016, 04:28 PM
Genoma² Paris, Fr
Thread OP
Discussion

Genoma². A competitive F5J User Built Glider


Dear Modelers,
F5J is getting more and more popular all over the world. At the same time, the planes are also getting more and more expensive (what I really regret).
I have followed this new category since the early days because I considered that this is the first time a TD glider has to be used for a TD competition (Most other TD categories require fast planes instead of real TD ones). This encouraged me to write some articles in RCSD starting in 2011. After my first plane, design in 2010, I developed new theories starting from scratch using the last F5J regulations published end 2011. The rational and the results were explained in RCSD Nov 2012.
Since this time 58 modelers from all over the world (and from 15 countries) have contacted me in order to get more details. Something like 35 planes are flying or under construction. That's the fairy tale of the Internet.
A few weeks ago, a team of 7 North American modelers approached me to also get some information. They wanted to make their own Genoma² using Ribs and D-box techniques, some of them are thinking of using a foam technique for the fuselage pod as for the 2004 Supra. I have flown the plane in F5J competitions in Europe for the past 3 years and have gained some experience to compare to other « F5J » planes (I also fly Pike perfection & Explorer 4000), I now have more data and better knowledge on the plane. I now have a better feeling as to whether or not the plane is competitive. And it is!
I then proposed to write the first post of the build log they wanted to create.
If you want to have your own top level F5J plane without spending 2000$/€, build yourself a Genoma².
This is an open source plane, and it circles better than any other plane you can find on the market."
Of course you can make any adaptations you want in order to have your own design. Just be advised that behind any dimension, profile, size, weight, etc. of the Genoma², there is a scientific rational. So make your changes in order to improve the plane and share your rational.
The group is already progressing quite rapidly and have been communicating by email. If it looks like some steps have been missed then ask. We will make files accessible in this post.
Marc
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Apr 01, 2016, 04:44 PM
Ok that's high enough
FabFlight's Avatar
I have a first seat in this thread, so I'll provide links to a few key posts & information. I will update links as we progress :

Construction Manual (translated and augmented by the community):
  • Part 1: Elevator and Rudder (Rev. 1 - April 19 2016)
  • Part 2: Fuselage (Rev. 1 - May 3 2016)
  • Part 3: Wing spar and joiners (available soon)
  • Part 4: Wing, molding & assembly (available soon)
  • Part 5: RDS actuators (not yet available)

Key information and posts:
Marc Pujol's publications about the differents Genoma(s):
Other useful stuff:
Last edited by FabFlight; May 03, 2016 at 10:29 AM.
Apr 01, 2016, 05:29 PM
Leonard
mac44mag's Avatar
Count me in!!

Leonard (mac44mag)
Apr 01, 2016, 06:17 PM
Ok that's high enough
FabFlight's Avatar
We've been discussing the spar construction (by email). I suggested to use vertical fibers or +45/-45 degrees. Curtis provided this excellent reference.

What I retain from this is that the tension/compression forces in the shear web are indeed at 45 degrees. There seems to be no tangible advantage to have the fibers horizontal or vertical (both almost the same). But there is when the fibers are laminated +45/-45. According to Drela, that is 2.5x more. According to other publications, 4x more.

On the other hand, in real word testing, all failures seems to have appeared in the joint between the web and the cap, and this seemed to be the overall limiting factor. Most participants acknowledged that wrapping the assembly is the best way to improve this failure mode.

Another thing that I understand from this discussion is that thickening the spar cap is not an efficient way of increasing the strength. I think we should seek help to redesign this aspect of the spar. Personnaly, I would go with +45/-45 webs and solely adapt the width to the span load progression, although I do not have the skills to do these calculations.

Using a laser cutter, we could alleviate the burden to cut balsa at 45 degrees. A standard sheet of 24 x 48 inches x 1/8 in will provide approximately 35 strips of 210 mm x 3.17 mm x 15 mm. Making the +45/-45 lamination is easy with a straight edge and thin CA. Then shape the spar normally.
Apr 01, 2016, 06:49 PM
Registered User
I am looking forward to the build and the discussion on this thread. I hope to be able to contribute where I can and to learn a lot from those more knowledgeable than me.
Apr 01, 2016, 10:14 PM
Registered User
Jebera's Avatar
Hello Marc,

Please share more files and links on the Genoma, please!

André
Apr 02, 2016, 01:47 AM
Genoma² Paris, Fr
Thread OP
First of all, few photos of what it is and what it might be in the future.

First of all, you have some photos in this link (sorry, in French)
http://www.f3news.fr/t3812-une-nouve...-f5j-unlimited

http://www.f3news.fr/t5416-genoma-2012

http://www.f3news.fr/t8592-le-genoma2-2014

Constructing a 4m plane in ribs is a quiet long job. It tooks me 100 hours and I'm not a slow builder. You can also use the "Supra" techniques. This will reduce your building time.
Whatever the techniques you choose, it will be a real good experience because this plane includes all the up to dates building techniques.
And Up to dates, doesn't means complicate or expensive. Standard tools can be used only. Of course, we now can have access to CNC machines, 3D printer, laser cut machine... So take advantage of it.

For the spar, You can discuss a lot on the aim, whether or not you have to put the balsa grain vertical, at 45 deg or horizontal.
For sure 2*45° is the best. Then vertical is simple and really good in terms of resistance and horizontal is the worth.
This rational is valid if you compute your spar in order it breaks if it reachs the limit. But I prefer to compute the spar in order to manage the deformation. I want a limited deformation under stress. After few computation and trial, a margin factor of 2 is a good things. Then, the aim is very less stressed and you can do it the way you want. Personnaly, I took the worth solution without any issues (never broke a wing even in a vertical crash.
The rational of having such factor of 2 has several objectives:
1) Think deformation
2) have some margine because you always do some mistakes in a construction. So be to the safe side
3) think also torsion. A wing never fail in pure flexion. It always died in torsion plus flexion. And torsional behaviour is quiet more "sensitive" to compute. I made a sort of approximation with an excel file in order to have a rough of magnitude. Be sure that torsion is the more important things. So having a margin factor is a way to be safer.
Actually, the genoma2 when constructed with Kevlar, is limited in torsion. It goes flutting aver 80 to 100km/h. Constructed with carbon, the limit is higher. So I recommand you to use Carbon only and to avoid Kevlar.

Marc
Last edited by marc.pujol; Apr 02, 2016 at 02:00 AM.
Apr 02, 2016, 02:13 AM
Genoma² Paris, Fr
Thread OP
During the night, our friend of Saint Remi made some translations that may be very usefull for a non French reader.
So here are some files that will help you in your project whatever tghe way you will construct it.

Marc
Apr 02, 2016, 06:55 AM
Registered User
In the build manual there are references to wood dimensions that I do not understand. In French "4 lattes de balsa 10/10ème ou 15/10ème," or English ", 4 strips of balsa 10 / 10th and 15 / 10th". Can someone explain these?
Apr 02, 2016, 07:00 AM
Genoma² Paris, Fr
Thread OP
10/10 means 1mm thick.
15/10 means 1.5mm thick
etc.
Now you can translate in inches!
Apr 02, 2016, 09:11 AM
Registered User
Rudix's Avatar
Thanks Marc and everyone contributing to this thread, it is going to be a great one!

If I can get my workshop back-log cleared I would love to start on a Genoma²

Rudi
Apr 02, 2016, 11:57 AM
Callused Thumbs
rafterrc's Avatar

At the Start


Back on February 13, I mentioned to Leonard (mac44mag) that I was planning to build a Genoma (no version selected). I had found most of Marc's RCSD articles centered around it, and the French construction zip. My thought, finally somebody has illuminated sesigning a TD sailplane around what I have observed and experienced. The primary difference in the Genoma (all versions) that excited me is the tail boom length, and, thereby, improving lateral and longitudinal stability. This also contributes to it's ability to circle in those tight lower level thermals. This is essentially all I needed to know in order to decide that I am going to build one or two. I am planning foam core Supra techniques, and leaning toward the Genoma 3 with fuselage length at 2.5m. (I'll find some way to haul the fuselage in one piece - probably in a little used 3 horse trailer.)

There are competing objectives present in a build of any kind. In this case, you have flight characteristics on the one hand. Transportability works it's way in for each of us. (I can walk about 20 meters and launch if I want to.) You probably do not want to buy a trailer for the plane. Then there are issues of buildability for your capabilities or capabilities you want to develop. Flexibility is key for me, so it should be able to fly in a broad range of situations and I should be able to take advantage of what I find. You need to decide up front those objectives you want to fulfill in both the building and flying, and stick with them.

There is much about this project that could be intimidating like it's a scratch-built, the buildocumentation is in French, the size, the composite D-box for the built-up wing, making the tailboom and pod. I recommend that you decide that you are going to work through the learning curve on such things. (Although, I believe Cricklewood is working on translating the documentation, I hope with some help from Google Translate.) Curtis has some videos that will help. There's a large amount of information on the Supra.

What follows will be all of us planning to build one making sense of all the details surrounding the build. Seven of us have been communicating by email. I believe this will be a unique build log. Most are about one person building something. This will be a bunch of people figuring out how to build a Genoma, and then building it. Marc has blazed a trail
Last edited by rafterrc; Apr 02, 2016 at 05:26 PM.
Apr 02, 2016, 11:59 AM
Callused Thumbs
rafterrc's Avatar

At the Start


Back on February 13, I mentioned to Leonard (mac44mag) that I was planning to build a Genoma. I had found most of Marc's RCSD articles centered around it, and the French construction zip. My thought: finally somebody has illuminated sesigning a TD sailplane around what I have observed and experienced. The primary difference in the Genoma (all versions) that excited me is the tail boom length, and, thereby, improving lateral and longitudinal stability. This also contributes to it's ability to circle in those tight lower level thermals. This is essentially all I needed to know in order to decide that I am going to build one or two. I am planning foam core Supra techniques, and leaning toward the Genoma 3 with fuselage length at 2.5m. (I'll find some way to haul the fuselage in one piece - probably in a little used 3 horse trailer.)

There are competing objectives present in a build of any kind. In this case, you have flight characteristics on the one hand. Transportability works it's way in for each of us. (I can walk about 20 meters and launch if I want to.) You probably do not want to buy a trailer for the plane. Then there are issues of buildability for your capabilities or capabilities you want to develop. Flexibility is key for me, so it should be able to fly in a broad range of situations and I should be able to take advantage of what I find. You need to decide up front those objectives you want to fulfill in both the building and flying, and stick with them.

There is much about this project that could be intimidating like it's a scratch-built, the buildocumentation is in French, the size, the composite D-box for the built-up wing, making the tailboom and pod. I recommend that you decide that you are going to work through the learning curve on such things. (Although, I believe Cricklewood is working on translating the documentation, I hope with some help from Google Translate.) Curtis has some videos that will help. There's a large amount of information on the Supra.

What follows will be all of us, who are planning to build one, making sense of all the details surrounding the build. Seven of us have been communicating by email, and the energy level is high. I believe this will be a unique build log. Most are about one person building something. This will be a bunch of people figuring out how to build a Genoma, and then building it. Marc has blazed a trail, but I expect that we all will help improve it.
Apr 02, 2016, 12:43 PM
Registered User
I am hoping to talk to someone who builds carbon fishing rods about making a tail boom for me. In the fuselage manual it talks about dimensions for a tail boom, 38 mm diam. tapering to 32 mm or 32 mm tapering to 25 mm. I am looking for suggestions on the optimal, if there is such a thing, tail boom dimensions if one is having one made or building their own.
Apr 02, 2016, 12:48 PM
Registered User
Yes, I am working on a translation. It is slow work but I almost have the first one done, Stabilizer and Rudder. I will link it into the thread once done and will be looking for feedback and corrections.


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