RE: Batteries running-in and swollen batteries
"..Thunder Power recommends no more than 3-5C average discharge for breaking in new packs.." This is 15-25 Amps for 5000 pack, which is too low even for takeoff. Meaning you need to put it on stand for the proccess. How many cycles are needed for a complete break in according to Thunder Power?
Posted on: 9/17/2012 12:21 AM by Author "ytell" in the forum "Electric Pattern Aircraft"
http://www.rcuniverse.com/forum/fb.asp?m=11230706

using old lipo
Are there any safety considerations in using 2-3 year old 5s lipos (Zippy or alike) that were not in use? They are all 20-30 cycles , some were stored fully charged and others approx. half. No special storage conditions (in house) Is there any test criteria that I can use for screening the bad from the good? Would appreciate any tip Yoav
Posted on: 8/30/2012 12:18 PM by Author "ytell" in the forum "Electric Pattern Aircraft"
http://www.rcuniverse.com/forum/fb.asp?m=11211731

RE: 62
As far as I can tell from the photos: 1) There is no rudder trim. Or is there? Was your model ON when the pic was taken? 2) The right aileron trim is noticeable only for the inner side of the ailerons. the outer seems perfectly align with the wings trailing edge. Is this correct? Just to complete the picture, how does it fly? Can you point any bad habit or flying quality that can be attributed to the left aileron trim?
Posted on: 8/24/2012 4:08 AM by Author "ytell" in the forum "Electric Pattern Aircraft"
http://www.rcuniverse.com/forum/fb.asp?m=11204245

RE: 62
can you post a photo from the rear so we could see how parallel is the horizontal stab with the wing and also the ailerons in neutral position (trimmed)?
Posted on: 8/18/2012 3:26 AM by Author "ytell" in the forum "Electric Pattern Aircraft"
http://www.rcuniverse.com/forum/fb.asp?m=11197594

RE: 62
Can you tell if inverted level flight leads to the same result? can you fly upright and inverted hands off with the same trim?
Posted on: 8/17/2012 11:27 PM by Author "ytell" in the forum "Electric Pattern Aircraft"
http://www.rcuniverse.com/forum/fb.asp?m=11197535

RE: 62
I'd suggest heavy wing check first Yoav
Posted on: 8/12/2012 9:01 AM by Author "ytell" in the forum "Electric Pattern Aircraft"
http://www.rcuniverse.com/forum/fb.asp?m=11190381

RE: CG location when fuel is burned
Da_rock, Even though there may be thousands of acting moments that determine CG (the entire AC) only one is changing from start to finish of the flight and that is fuel tank. Therefore it is (i think) justified to neglect all but this moment in calculating a change in CG position. John, you wrote: "Then the distance of this calculated moment is: New Dist to CG from Leading edge = dist * (ACEWT + FUELWT) / New total weight" and then: "Since the total weight is ACEWT + FUELWT " But I say this is not true. We need to compare beginning of flight to end of flight (fuel consumed) and therefore, total weight does not equal the same "ACEWT + FUELWT" because FUELWT has changed and that is why dist has change too
Posted on: 6/17/2012 11:53 AM by Author "ytell" in the forum "Aerodynamics"
http://www.rcuniverse.com/forum/fb.asp?m=11121350

RE: CG location when fuel is burned
John, I perfectly understand that CG will not change if tank is on CG. What I fail to understand is how to show this using datum calculation. If you take moments about (say LE) then you have: Chnage-of-moment = (moment_flight_start)-(moment_flight_end) = dist_to_LE*(weight_full_tank - weight_empty_tank) Since the expression in the last parenthesis is greater than zero, I find that CG has changed Yoav
Posted on: 6/17/2012 10:53 AM by Author "ytell" in the forum "Aerodynamics"
http://www.rcuniverse.com/forum/fb.asp?m=11121307

RE: CG location when fuel is burned
John, These two weights are not the same. the second is lesser than the first becuase fuel has been consumed so FUELWT-1 is grater than FUELWT-2 and so you can't conclude that "dist" remain unchanged All, the point that is still unclear to me is why the datum calculation of CG does not show that CG remain unchanged even though fuel tank (full and then empty) is installed exactly on AC empty weight CG? Thnaks, yoav
Posted on: 6/17/2012 9:35 AM by Author "ytell" in the forum "Aerodynamics"
http://www.rcuniverse.com/forum/fb.asp?m=11121207

RE: CG location when fuel is burned
Sorry for being slow on this... 1. If CG is calculated about empty CG, than the arm is always zero and fuel amount has no affect. 2. If CG is calculated about LE, then the moment of fuel tank is the product of the arm (constant) times the weight of the fuel (changing). As a result, the CG will change as fuel is consumed. Am I missing something?
Posted on: 6/16/2012 10:31 AM by Author "ytell" in the forum "Aerodynamics"
http://www.rcuniverse.com/forum/fb.asp?m=11120257

RE: CG location when fuel is burned
But still, if the tank is located exactly on CG, I'm expecting CG position not to change when fuel is consumed. However, if you calculate CG position with a datume line you will find it changed from full to empty. so waht's going on?
Posted on: 6/16/2012 8:08 AM by Author "ytell" in the forum "Aerodynamics"
http://www.rcuniverse.com/forum/fb.asp?m=11120144

CG location when fuel is burned
I'm a little confused on this one, If the fuel tank is located exactly on CG, there will be no change in CG position throughout the flight. But if you calculate CG position relative to a datum (say leading adge) you will calculate a different CG location when the tank is full or empty. How can this contradiction be explained? Yoav
Posted on: 6/16/2012 7:20 AM by Author "ytell" in the forum "Aerodynamics"
http://www.rcuniverse.com/forum/fb.asp?m=11120104

YS-FZ110 dies on idle only in flight
My YS-110 runs smooth and powerful. No problem on ground checks at all RPM. Throttle transition is also good. In flight ferformance is also very good however, when closing to idle for landing, it will die. One thing I've noticed is considerable air bubbles when throttle in idle position in the fuel line from the air chamber to the engine intake. Is this normal? Would appreciate any tip Yoav
Posted on: 6/15/2012 1:06 AM by Author "ytell" in the forum "YS Engines Support"
http://www.rcuniverse.com/forum/fb.asp?m=11118849

RE: Questions on my 3D hobbyshop Osiris
From what I hear from F3A-Unlimited, this setup should give you enough power for the Osiris. I would recommend to check if you really need the full throttle on the up-line. Try to open the throttle just to keep a constant speed without accelerating. Throttle management in EP is a major issue compared to IC planes. Yoav
Posted on: 6/24/2011 10:55 PM by Author "ytell" in the forum "Electric Pattern Aircraft"
http://www.rcuniverse.com/forum/fb.asp?m=10591249

RE: the rational of trimming
So, back to aerodynamics (the science, not the politics) and trimming, Is there a rational for playing with wing incidence or decalage? I think it is comonly agreed that since the the wing is that flying and everything else follows what is the point in making changes in wing incidence in a pattern model? (assuming fuselage AOA is not a factor) Yoav
Posted on: 6/6/2011 12:40 PM by Author "ytell" in the forum "Aerodynamics"
http://www.rcuniverse.com/forum/fb.asp?m=10559866

Trimming knife-edge flight
Hi, Found an interesting method for knife-edge flight with no need of radio mixing by playing only with CG: Trim your model to fly hands free straight and level. If the model is carrying up elevator trim to hold level flight when rolling to knife edge the up trim will take over and cause the airplane to go to the canopy, the opposite happens when the CG is too far back (credits to Andrew Jesky) Could someone explain the physics behind this? What is this point of CG in which the model will fly hands free in both S&L and NE flight. Is this a point of zero tail lift? Neutral point? or something else? Would you expect that this point will also be close to hands-free vertical lines as well (assuming trust line is OK) Thanks, Yoav
Posted on: 4/23/2011 6:30 AM by Author "ytell" in the forum "Aerodynamics"
http://www.rcuniverse.com/forum/fb.asp?m=10479856

RE: the rational of trimming
Suppose Bryan's method is adopted as described. What flying qualities will you gain? Is it just pros without cons? I can think of at least one big issue, at least for me, as a result of a quite a bit of forward CG which means that your inverted flying will no longer be close to a trimmed (hands-off) flight as upright. So I'm thinking if it would not be wise to follow other trimming methods which are more tolerated to an aft CG and when you're close enough just mix out the remaining problems with your radio. Do you see any flaw with this approach? Yoav
Posted on: 12/13/2010 9:40 AM by Author "ytell" in the forum "Aerodynamics"
http://www.rcuniverse.com/forum/fb.asp?m=10194325

Flat turn
How can a model turn flat with rudder only and not be affected by the greater speed of the outer wing? Thanks, Yoav
Posted on: 12/13/2010 9:15 AM by Author "ytell" in the forum "Aerodynamics"
http://www.rcuniverse.com/forum/fb.asp?m=10194274

RE: simulator for pattern practice
OK, found the problem. Didn't use the .geo file Thanks anyway Yoav
Posted on: 11/24/2010 2:31 PM by Author "ytell" in the forum "Electric Pattern Aircraft"
http://www.rcuniverse.com/forum/fb.asp?m=10156980

RE: simulator for pattern practice
Hi Dan, I didn't know about the grid idea so I rushed to rc-sim.de and downloaded the Farmland-grid scenery into my AFPD but when I loaded the scenery no grid is visible. Any idea if there are any special requirements or procedures for this to run? Thanks, Yoav
Posted on: 11/24/2010 12:49 PM by Author "ytell" in the forum "Electric Pattern Aircraft"
http://www.rcuniverse.com/forum/fb.asp?m=10156780

building is great, what about flying?
OK, you've build the ultimate plane (e.g Nagary's Xigris), but what about flying? You don't find many flying tips in the forums, why? What practice techniques will bring you from sportsman level to FAI? How do you practice a new schedule? A new single maneuver? Do you use a simulator before going to the flying field? Are you using your 2X2 plane for regular training or maybe a cheap foamy until you master the maneuver? Any written stuff on the subject? Interesting links? What’s your view? Thanks Yoav
Posted on: 11/20/2010 7:21 AM by Author "ytell" in the forum "Electric Pattern Aircraft"
http://www.rcuniverse.com/forum/fb.asp?m=10147112

RE: Osiris Kudos
Any idea where the Osiris can be purchased? On 3Dhobbies it is sold out. Yoav
Posted on: 10/13/2010 3:18 PM by Author "ytell" in the forum "Electric Pattern Aircraft"
http://www.rcuniverse.com/forum/fb.asp?m=10066430

RE: x9303 setup problem
Answers: Not sure if the deflections are big enough to be seen on the monitor screen. Can you please explain how can it help me? The flap channel is inhibited I AM using FM for trimming but there is still a difference in the aileron position (only) for each FM unless I change it to trim=com and trim each flight mode separately Thanks Yoav
Posted on: 9/19/2010 9:42 AM by Author "ytell" in the forum "JR Radio & Spektrum Radios"
http://www.rcuniverse.com/forum/fb.asp?m=10012365

x9303 setup problem
Hi Everyone, I'm having a difficulty while setup Spark pattern ship with my X9303 radio. The plane uses 2 servos for ailerons and two halves of the elevator. I'm using 3 flight modes with different ranges in each mode. The problem is seen on ailerons only and can described as follows: when I switch between the modes (with different ranges) the neutral position in each mode is different and you can actually see the aileron moving to a new position each time you choose different mode. The only way I can eliminate the problem is by choosing Trim=COM on Device Sel. screen and than trim all 3 modes separately. Obviously I'd like to be able to use Trim=COM with common trimming for all three modes. In searching for a solution I tried to eliminate using Flight Modes and even programming my model from scratch but with no success. Would appreciate any help. Thanks in advance Yoav
Posted on: 9/18/2010 1:14 PM by Author "ytell" in the forum "JR Radio & Spektrum Radios"
http://www.rcuniverse.com/forum/fb.asp?m=10010770

RE: Spark F3A, from Krill Models - SPAIN TEAM
Hi Jason, It's the Dynamic model with Plattenberg X-30 Evo and YGE-95 ESC. I think I understand where the CG confusion is coming from. Krill specifies the CG relative to root chord (30mm ahead of wing tube) while Bryan suggests that you start the trimming procedure while your CG is at 25% MAC. I tried to convert Krill recommendation to be relative to MAC and got 25%MAC. At this point I'll stay with battery pack on the landing gear assembly (estimate 30%MAC) while changing only Incidences to the starting point and see how it goes. [image][/image] Regards, Yoav
Posted on: 9/4/2010 12:26 PM by Author "ytell" in the forum "Electric Pattern Aircraft"
http://www.rcuniverse.com/forum/fb.asp?m=9980064

RE: Spark F3A, from Krill Models - SPAIN TEAM
That's very interesting Jason because I'm also trying to duplicate Bryan Hebert's trimming method and I've noticed that CG position is a key player in this respect. I currently have my battery exactly as yours (this was before I came across Bryan's method) and the CG position is about 37% MAC which is not only very rear to Bryan's starting point recommendation (25%MAC) but also rear to Krill recommendation (about 33% MAC). Obviously I'm not eager to move the battery as long as I know that Bryan's method will work (minimal radio mixes) by playing only with incidences. Would appreciate your view Regards, Yoav
Posted on: 9/3/2010 12:50 PM by Author "ytell" in the forum "Electric Pattern Aircraft"
http://www.rcuniverse.com/forum/fb.asp?m=9978300

RE: Spark F3A, from Krill Models - SPAIN TEAM
Hi Jason, You were right. Looking at my Spark wing it is exactly like yours and I see the hole near the trailing edge for pin of the adjustor. However, the holes on both the wing and the fuse are too small and need to be file 1-2mm to allow this pin to go through. is this the case on your Spark? BTW what is your CG position? (MAC) are you using the recommended position for battery tray on the landing gear assembly? Regards, Yoav
Posted on: 9/3/2010 7:42 AM by Author "ytell" in the forum "Electric Pattern Aircraft"
http://www.rcuniverse.com/forum/fb.asp?m=9977851

RE: Spark F3A, from Krill Models - SPAIN TEAM
Hi Jason, I think I'm starting to get the picture clear although I'm currently on a business trip (India) so the SPARK is not near by for detailed examination. I'm still puzzled however about the fact that the wing hole near the trailing edge (where the servo leads are exiting) seems to be much larger than the regulator pin, so what's keeping this pin (and the wing) exactly in place when assembled with the fuse each time? Thanks for your patient.. Yoav
Posted on: 9/1/2010 5:24 AM by Author "ytell" in the forum "Electric Pattern Aircraft"
http://www.rcuniverse.com/forum/fb.asp?m=9973403

RE: Spark F3A, from Krill Models - SPAIN TEAM
Thanks Jason, Where the male of the adjuster needs to feet in the wing? Can I mount the adjuster in the front side of the wing? as the plane is already build it will be much simpler than in the rear Regards, Yoav
Posted on: 8/31/2010 10:06 PM by Author "ytell" in the forum "Electric Pattern Aircraft"
http://www.rcuniverse.com/forum/fb.asp?m=9972904

RE: Spark F3A, from Krill Models - SPAIN TEAM
Hi everone, Need some help with incidence regulator installation on the SPARK. So far my bird flew with factory fixed incidence and I'm a little confused of how the wing will be secured to the fuselage when the incidence regulator is installed. Any clarification and installation pictures will be most appreciated. Regards, Yoav
Posted on: 8/31/2010 12:32 PM by Author "ytell" in the forum "Electric Pattern Aircraft"
http://www.rcuniverse.com/forum/fb.asp?m=9971679