|Aug 31, 2005, 09:58 PM|
Joined Mar 2005
Need help with Evolution Competition and F5B in general
I want to set up an Evolution Competition from Ripmax. It took me a long time to put enough money aside to achieve my dream i had during the last five years and buy a f5b model. I only had enough money to buy used equipment which took me a while but that is better than nothing.
Its extremely hard for a student to buy the equipment to take part in a competition because its just too expensive. This is a big problem. Many young skilled pilots which are really interested in competition, have absolutely no chance to earn the thousands of euros for competitive equipment. That is exactly the way which leads to a competition class which is not dominated by the skilled but by the wealthiest competitors. Someday you will only see the same faces on every competition.
Back to topic:
The drive is an old KBM39-16-3,7 with a 15" *13" Freudenthaler prop and an 3P Kontronik ESC, powered by 26 very old Sanyo N-1000s (one of the 27 cells already died during storage). Does someone know the current for this drive?
There are some problems which hold me from finishing the setup:
The fuse is made of thin glassfibre. I am not really sure how to reinforce it. I plan to use four strings made of four 1600Tex carbon fibre rovings each. I want to place them in the edges of the fuse under the wing and on the bottom on every side. They would reach from the nose to the tail to reinforce the thin fuse when I pull the elevator ;-)
In addition to that I would use a vertical ring made of four rovings just in front of the LE and a thin layer of aramid with half of the height of the fuse from the spinner to the end of the akku.
The problem is that if I make the fuse too stiff, the wing will be damaged by the steel screws on every hard landing.
Would that be too much or too less reinforcement for the tail?
How could it be done better? Does someone have experience with his own Evolution Competition?
The materials I have are:
- a lot of carbon fibre roving
- some small pieces of the aramid cloth (? g/m²)
- some small pieces of carbon cloth (~160g/m²)
- Balsa wood ;-)
There is definitively no money left to buy any new cloth.
The second problem are the HS125 Servos for the ailerons. I was shocked when I dropped them into the huge hole I needed to cut out of the wing. They are just as thick as the wing. No chance to use a normal servo cover.
I sanded the servos as far as I thought it would be safe. Now they finish in the plane of the wing surface. Does someone now where I can get very thin (red would be best) servo covers for a student-adequate price?
Would it be useful to add flaps to the wing? Will that weaken the wing too much?
I would be so thankful about an active f5b pilot in the range of Berlin or Brandenburg who is willing to give me some tips and show me some flying techniques.
|Sep 01, 2005, 09:38 AM|
Sorry but without flying skill, you will never win a F5B or F5F competition, even with the best equipment.
And with a lot of flying skill, but not the very best equipment, you can still be competitive in national competitions.
The best european pilots are making the airframes, spinners, and props themselves
I do not know the Evolution Competition in detail, but normally you do not need to make a lot of reinforcements to a F5B/F5F airframe.
If you are going to make the reinforcements, then watch out for the weigth increase.
You can not use 26, or 27 cells for competitions, because your max. is 16 Sub-C cells for F5B today, so you need some new (or used) cells too.
But keep up the good spirit, and get the Evolution Competition flying, and do a lot of training with the equipment you can afford, and you will be competitive some day.
|Sep 01, 2005, 09:53 AM|
Given your location, you should be able to locate a pilot within a short distance who could help with this airframe. I would caution you against making further modifications before consulting with a more experienced modeler. Sanding servos to get them to fit was a bad idea, covers are often not used, just tape to seal the hole. Many times, servos to protrude above the wing skin. The flex in the fuselage may be there by design, stiffening it might lead to total destruction on a hard landing, rather than a few cracks that could be easily repaired. Finally, besides the fact that F5B use will age cells prematurely, they also have a shelf life, and those cells may be completely unusable at anything more than "sport" power levels (20-40A or so), at reduced capacity.
Again, I'd find a local modeler to discuss this with, or slow down and address each issue here in detail before jumping in.
|Sep 01, 2005, 11:23 AM|
Joined Mar 2003
For whats its worth, i suffered a hard landing on my evolution , no problems with the fus just a few hairline cracks and some chipping of the gel coat. The real pain was that the steel bolts held firm and the wing holes became elongated resulting in a wing that was no longer abled to be securely tightened to the fus without lateral movement and the bolts also pulled the fastening bolts loose from the fus. I would suggest strengthening around the holes in the wing ( perhaps with the little plastic washers available from aircraftworld) and perhaps using nylon bolts instead!!
|Sep 01, 2005, 12:44 PM|
The fuselage does not need any reinforcement. In a hard landing the boom will break, but it is easy to fix. But if you run carbon all the way down it will still break but be more awkward to fix. The wing is very strong also.
The motor takes about 100A on 27 cells with the 15x13 prop. The performance will be similar(ish) to a legal 16-cell setup. Fly what you have until you can afford new cells. Then use the 39-16 with 16 cells and a 18x19 prop. If you still like F5B you can then buy a new motor and controller.
Regarding your comment about young, skilled and poor pilots...most of us old(er) less skilled but more wealthy pilots were young and poor once. We did not fly moulded models - we built them ourselves from balsawood, foam and veneer.
|Sep 01, 2005, 03:54 PM|
Joined Mar 2005
First, I want to thank you for your answers.
I think, my criticism on F5B was misunderstood somehow. I did not want to offend someone of the "older" pilots. If someone feels so, then please excuse my clumsy words. I did not want to upset someone. I just expressed my frustration which grew during the last years
I did not really want to say that the wealthiest pilot will win every competition. There is still a lot of skill needed to be competitive, but without lots of money and a self built model in Styro Abachi with a cheaper motor and without pushed cells even the most skilled pilots won't be competitive. It would be much easier for me to express my thoughts in german than in english
The problem of a benadble fuse appears at high speeds. This could lead to a very disturbed flight during the turns or at high speeds.
You are right with the cells, but I dont have any alternatives. I have to try the high currents, otherwise it would take a while to buy new cells and the maiden won't happen this year.
Did you make any reinforcements to your fuse? M3 Nylon bolts don't seem to be a good choice to handle the high stresses. I would not feel comfortable flying this model with M3 Nylon bolts
Do you think the boom is stiff enough that it won't bend in flight?
In the past I have built most of my models out of foam and veneer. Unfortunately this would take too much time nowadays.
|Sep 01, 2005, 04:08 PM|
The fuz doesnt need reinforcements as Mike says, but I run carbon tow around the wing opening and under the lip on the fuz where the leading edge of the wing sits.
Be careful of the wing bolt mountings in the fuz, as sometimes overtightening pulls out the inserts if the flange isnt fully intact. This can lead to the wing pealing off in flight. (Dont ask how I know )
I always found the Evo torqued to the left on launch, so be careful of that.
|Sep 01, 2005, 04:16 PM|
I think we all understand your frustration. I started with self made models and second-hand motors and batteries because I could not afford anything else. I then got the chance to buy a couple of moulded models for the 1996 World Championships and my flights improved a lot. But for the 1998 World Championships I had the choice of a brushless motor OR a new model, but not both, so I had to start building my own again. It was only in the last few years that I have been able to buy motors and models...and now I feel that my flying is not as good as it was when I was younger
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