RE: Batteries running-in and swollen batteries
I don't know if break-in is good or irrelevant, seems like it's a good idea. I break-in new packs on a test stand where I can monitor individual cell volts and overall output. Stand is equipped with a low cost motor that can handle 30A for 6 min. Packs are allowed to cool completely before charging after each run and the process is repeated 5X. Using brand name packs I've not experienced any early failures - but it may not be absolutely necessary. A much more important practice as packs age is to check the individual cell volts at the beginning of charge. The balance connectors on packs (and any extensions) deteriorate with use and can provide false info to the balancing circuits of the charger. Of course, that means the balancing attempts of the charging system will be in error, possible over / under charging some cells. Kinda defeats the purpose of balancing! It's very important to determine if errant cell voltage is correct or a connector problem before "mis-charging" the pack! Sometimes cleaning the connectors will fix the issue, sometimes "tightening" the connector is needed, and frequently several strands of the balance lead are broken at the connector resulting in big voltage drop when balancing current is flowing. A little observance / maintenance here will result in longer batt life.
Posted on: 9/16/2012 9:09 AM by Author "EHFAI" in the forum "Electric Pattern Aircraft"
http://www.rcuniverse.com/forum/fb.asp?m=11230012

RE: 150 meter rule.
nonstoprc The ET GPS specs state position accuracy of 2.5m (8.2 ft) and speed accurace of 0.4 m/s (0.9 mph). I've found the repeatability suitable for pattern use. When using the pressure based altitude sensor the absolute altitudes may not always agree with the GPS data, but the delta is consistent. The GPS uses dual antenna to accomodate rolling / inverted flight and the pressure system can be affected by pressure changes at the pitot reference port when the airplane is pitching / rolling. So, there is a little noise in the data. With the large volume of data available it's not hard to smooth it so as to see what's going on with the airplane. For example, in figure M it's real easy to measure the entry / middle / exit altitudes and the max altitude of each leg close enough to see errors and make adjustments in one's flying until the errors disappear. My observation is that large errors recorded with the ET are also noted by judges and the judges precision isn't generally as good as the ET. So - all in all - a useful tool for working on geometry and position. Can't beat a good coach for S & G.
Posted on: 9/15/2012 9:47 AM by Author "EHFAI" in the forum "RC Pattern Flying"
http://www.rcuniverse.com/forum/fb.asp?m=11229319

RE: 150 meter rule.
The resolution of the ET GPS appears good enough (usually using 9 sats). For example, one can easily determine "roundness" of rolling circles (or 8's) as well as size, as these are in a horizontal plane. Vertical maneuvers are more difficult, some of which lies with the ET viewer. The data are compiled so as to present a track relative to time and we fly a sequence in the same space (box). So the track of each maneuver overlays the previous - it ends up looking like chicken scratch. That means each maneuver (or a couple at most) must be done individually, which is very time consuming. Some work has been done to translate the data into a 3D "box" which would allow an entire sequence to be scrolled through on a maneuver by maneuver basis referencing the time base. It would also be possible to look at a maneuver from various viewpoints. I'll let the persons working on this to comment further if they wish - but work in progress. Another trick that might work is to switch the logger off/on in flight (which starts a new data group) to limit the overlaying of maneuvers during a sequence - haven't tried that yet.
Posted on: 9/14/2012 8:03 AM by Author "EHFAI" in the forum "RC Pattern Flying"
http://www.rcuniverse.com/forum/fb.asp?m=11228305

RE: 150 meter rule.
Joe The speed thing is another whole can of worms. I've measured both airspeed with a pitot and ground speed with GPS. Of course, the GPS speed is only valid in level flight while the wind must be factored into the pitot speed. One things certain - constant speed is more of a perception than a fact! Even a simple loop that appears to be flown at "constant speed" will actually vary considerably throughout the maneuver. Usually I fly a sequence or a practice session, then apply the data I'm interested in to Aresti of the sequence(s) flown. Actually, altitude is the most telling as one can observe entry / exit alts, loop dia, etc. So, I don't have data handy that shows just level flight speed at some throttle setting (something to work on). Picking data from sequence entry or rolling maneuvers the 70 - 80 mph number is pretty close. Yes, the box gets short quick @150M - explains why a lot of designers / pilots have a focus on slower speeds and other pilots fly way out. Unfortunately, I tend to use this data to sort out new sequences / equipment and don't really keep good files - at least with coded names that make sense a year or so later. I've learned a couple of "tricks" for using the ET GPS, (at least mine) doesn't work above 6v supply - I use a 5.2v reg between it and the power source. Mounting the GPS RX in the wing works well (1/8" x 1 x 1 slot in the foam) - CF and power unit stuff can block the signal. Initial satelite acquisition takes a couple of minutes - each power up during that days work then are quick. Lock on to sats in the pilot box, then the closest distance shown each pass is the distance out (in front of the pilot).
Posted on: 9/13/2012 11:57 AM by Author "EHFAI" in the forum "RC Pattern Flying"
http://www.rcuniverse.com/forum/fb.asp?m=11227429

RE: 150 meter rule.
2Sunny A nifty way to determine your flight distance is to use the EagleTree datalogger with GPS. The data translate directly into Google Earth and will show your flight track relative to the runway. Use the measuring tools of GE to measure the distance out. You'll also be able to observe if your flight path is parallel to the runway, consistant in distance, and straight. I think that you're correct in that many folks fly outside of 200M, so many that it's become the norm with many judges. A side consequence is that those flying at 150M tend to be penalized for lack of smoothness and small errors which become more visible when occurring closer. Flying slower smoothly and accurately at 150-175M is more difficult than a fast open style at 250M - hence rules requiring downgrades for flying too far out. I don't believe excess distance is downgraded properly much of the time because it's not easily determined until really excess. Also, a pilot / judge who flies at excess distances is unlikely to downgrade others for what appears normal basis their style. Of course, there's no downgrade out to 175M (why aren't the poles there?) and this is a good distance. I think you'll find the successful pilots in major competitions tend to stay within this limit. Earl
Posted on: 9/12/2012 10:24 AM by Author "EHFAI" in the forum "RC Pattern Flying"
http://www.rcuniverse.com/forum/fb.asp?m=11226237

RE: CAELESTIA NEW F3A 2011
Looks good Chad. What are the wing weights?
Posted on: 3/21/2012 12:46 PM by Author "EHFAI" in the forum "Electric Pattern Aircraft"
http://www.rcuniverse.com/forum/fb.asp?m=11009738

RE: Source for some Nomex honeycomb
ACP Composites has honeycomb panels. http://www.acpsales.com/OnlineStore.php?cat=4965 .
Posted on: 3/8/2012 2:20 PM by Author "EHFAI" in the forum "RC Pattern Flying"
http://www.rcuniverse.com/forum/fb.asp?m=10991877

RE: Question for lucky 18MZ owners
Jim The TX S Bus program center offset minimum increment is the same 0.25 deg as you report for the programmer. The end point minimum increment is 0.5%.
Posted on: 2/28/2012 4:03 AM by Author "EHFAI" in the forum "RC Pattern Flying"
http://www.rcuniverse.com/forum/fb.asp?m=10979643

RE: 2 Meter Pattern Plane Servos ?
The question I originally set out to answer was "Are the servos strong enough so as not to result in control surface slowing while moving for a snap roll". My goal was to measure the servo current draw during this condition and use that info to study the speed of the control surface on a bench rig. The elevator / ail snap set-up measured was a DR step function, stick activated, with minimal AFR limiting and no expo - pretty simply on/off (switch safety) max travel, which then transitions to normal behavior after the initial "hit". Initial observations were that current was high on the elv and "normal" on everything else. Knife edge loops were then flown to observe max rudder current draw which was relatively low. Measurements during normal F3A sequences were considerably lower, in fact, lower than I expected. The same servo was then mounted on a rig and connected to linkage geometry / control surface dimensions as the airplane. The same current sensor was installed and the servo driven from the airplane RX using the same TX program used in flight. A variety of springs were attached to the "control surface" until the current signal / amplitude matched that observed in the airplane. Another rig fitted with linkage / pot so as to provide a voltage output was connected to the "trailing edge" of the "control surface". The voltage output from this rig was fed into a PC stripchart (poor man's storage scope) which provided a means to measure travel vs. rate and can be expanded sufficiently to measure / observe the time from start / stop of movement. With this it was apparent that the rate slowed noticeably with the elevator servo and not with the other servos during the snap inputs. Changing the elevator servo to one 20% or so more powerful eliminated the slowdown. That's really the info I was interested in. Jim, as I recall the current draws measured in "normal" flight maneuvers were consistent with Ola's data. The rig draws were higher, as the load was set for max observed flight current. I'll send you the flight current files, I don't recall the details (been a year or so). Most of the rig current set-up was done with real time observations that I didn't record. When I get a chance I'll post some of the chart recorder files. Also interesting to set the rig up for "normal" loads and explore the different starting / speed characteristics of different servo types - but that's another story
Posted on: 2/5/2012 3:45 AM by Author "EHFAI" in the forum "Electric Pattern Aircraft"
http://www.rcuniverse.com/forum/fb.asp?m=10943913

RE: Epoxy CA hinges in place?
It's important to recognize that all CA hinges are not equal. An easy test is to grasp a hinge with two pliers butted together at the "hinge line" and try to separate / tear the hinge apart. Many tear as easy as paper, others can't be torn. I find Radio South Pro hinges always pass this test and hold up for thousands of flights in both glow & E powered pattern airplanes.
Posted on: 2/4/2012 5:47 AM by Author "EHFAI" in the forum "RC Pattern Flying"
http://www.rcuniverse.com/forum/fb.asp?m=10943143

RE: 2 Meter Pattern Plane Servos ?
Here're some data that may help you decide. I consider fast / constant servo speed critical for precise flight performance and choose the fastest servo with sufficient torque. I wanted more information as to what "sufficient torque actually was, so I designed an experiment in an effort to find out. Peak current draw was measured in flight on each servo during high load maneuvers, snaps, knife edge loops, high speed rolls, etc. Servos were of both brushless & digital variety. Servo voltage was regulated 6v from a LiPo source and the aircraft was a typical 2m E powered pattern model. These data were then used to measure servo speeds under load at the same current draw on the bench using a rig built for this purpose. A significant observation is that the servo speed is relatively constant until current draw reaches 60% of stall current. Probably a good target is 40% of stall current - here're data observed in this testing. On elevators, 2 X 60 oz in servos exceeded 60% of stall current (SC) and slowed measurably - changing to 75 oz in servos dropped the current draw to around 50% SC and speed is maintained. On ailerons, 2 x 128 oz in servos drew 30% of SC. On rudder, 1 x 300 oz in servo drew 20% of SC. Basis these results, it appears that minimum digital servo torque for this ariplane might be 150+ oz in for elevator, 75+ for each aileron, and 100+ for rudder to prevent servo slow down during stressful maneuvers. Be aware that linkage ratios will factor into this and that for this test ariplane the elevator linkage amplifies surface movement to increase travel speed (which will also increase servo load. Generally it's believed that stronger servos have more "holding power" and I didn't address that issue in this experiment. My "feel" over the years is that the digital servos provide more solid flight which may be related to better holding power. It was noted that servo current draw is extremely low in level flight in calm and very rough air.
Posted on: 2/4/2012 4:31 AM by Author "EHFAI" in the forum "Electric Pattern Aircraft"
http://www.rcuniverse.com/forum/fb.asp?m=10943066

RE: new spinner idea
Some time ago I made some measurements comparing the air speed behind the spinner of Tru-Turn spinners with their lightened backplate and with their Turbo-Cool spinner which has fan shaped spokes on the backplate and openings in the cone. http://www.truturn.com/cgi-bin/store/agora.cgi?keywords=cool&ppinc=1aelectrics130&maxp=30 I chose to measure airspeed, as motor temps are very dependant upon air ducting. Measurements were taken in flight using a pitot tube mounted 1/4 inch behind the spinner at a midpoint between the shaft and outer diameter. Results with no spinner, a standard spinner / solid backplate, a standard cone / lightened backplate / and the fan backplate - vented cone indicate the most flow speed with no spinner (comparison point for others) and no flow with the solid backplate / cone. The lightened backplate and solid cone resulted in airspeed of 35% that observed with no spinner. (This cone had larger than necessary prop cut-outs.) The fan backplate / vented cone provided 60% of the airspeed provided with no spinner (and looks way better). My conclusion is that a spinner with an internal fan and cone openings provides significantly more airflow than other systems. The cooling benefit of the extra airflow is highly dependant upon how the air flows through / over the motor.
Posted on: 1/31/2012 6:11 AM by Author "EHFAI" in the forum "Electric Pattern Aircraft"
http://www.rcuniverse.com/forum/fb.asp?m=10936596

RE: Will YS ever go gas/petrol?
The crop of available 2-stroke cycle engines, both SI & glow have developed around intake & exhaust functions that compete for cylinder volume. A technique not explored (to my knowledge) is a bottom feed 2-stroke engine. This system has intake ports around the bottom of the cylinder and poppet type exhaust valves in the head. A blower supplies intake air (can be supercharged) into the bottom of the cylinder which sweeps the exhaust gasses out the exhaust valves - fulling charging the cylinder. The crankcase compressing loads of a 2-stroke or YS are also absent from the piston downstroke. Kind of a hybrid 2 stroke having the cylinder filling of a 4-stroke (and the complexity of one) with the smoothness of a 2-stroke. Most of these type engines are large diesels - think locomotives - but it would be fun to look at the possibilities of a small model engine. Another possiblity is turbocharging the 4-stroke cycle engine. Our rpm range is high enough that turbo lag shouldn't be an issue. The turbo would not only add power, but act as a muffler. Most engine design options seem academic with electric motors doing a good job simply, but still fun to think about.
Posted on: 1/16/2012 11:27 AM by Author "EHFAI" in the forum "RC Pattern Flying"
http://www.rcuniverse.com/forum/fb.asp?m=10911770

RE: Pattern Rules Proposals
Bob An experience requirement for proposal submitters would sure cut down on discussions like this forum. OTOH, observations from a fresh perspective and / or "out of box" thinking has the potential for providing good and useful proposals. I suspect we're better off allowing proposals from all quarters and relying upon the experience of our contest board to sort it all out - these folks usually way exceed the experience requirement you suggest. A proposal that might keep the older generation more interested and competitive would be some form of score handicapping. I favor 0.5% addition to the score for each year of age, say above 55. Could really be made interesting if 0.5% were deducted from scores of those below age 30.
Posted on: 1/7/2012 4:09 AM by Author "EHFAI" in the forum "RC Pattern Flying"
http://www.rcuniverse.com/forum/fb.asp?m=10895958

RE: Futaba 18MZ
Steve Stick spring rate has often been a topic with the 14MZ. Will the 18MZ have a higher tension adjustment range, an option for high tension springs, a retro fit for higher rate springs, or will I need to wind my own again? I do have one on BO.
Posted on: 11/2/2011 8:19 AM by Author "EHFAI" in the forum "RC Radios, Transmitters, Receivers, Servos, gyros"
http://www.rcuniverse.com/forum/fb.asp?m=10793429

RE: CD Appreciation
Nuttin "softy" about saying "Thanks".
Posted on: 10/26/2011 1:44 PM by Author "EHFAI" in the forum "RC Pattern Flying"
http://www.rcuniverse.com/forum/fb.asp?m=10783865

CD Appreciation
We enjoy our participation in pattern events, the flying, awards, comradery, parties, and eats. The "historical" contests are pretty much expected to be there each year. We practice for these events and focus on the competition, knowing that if we show up and judge a couple of rounds the show will go on. Without contests we'd have no place to enjoy the challenge of matching our hard earned skills to those of others. The folks that make this happen year after year are the local event CD's. These folks make all the preparations, from getting club approval (for a low - no profit event), to providing score sheets. The logistics of putting on an event are considerable and the risk of a low turn-out real. We should all take a moment now, as the season is winding down, to offer a big THANK YOU to all the CD's and clubs that hosted pattern events during the year.
Posted on: 10/26/2011 3:02 AM by Author "EHFAI" in the forum "RC Pattern Flying"
http://www.rcuniverse.com/forum/fb.asp?m=10783028

RE: New Hacker ESC Senstrol
Essentially this system provides the same rpm for a given stick position regardless of battery voltage or motor load within the capability of the power supply (battery). Not much different than getting the same rpm for a given stick position throughout a flight with glow. Nothing here that changes the need for pilot throttle inputs, it just makes the result of those inputs more repeatable. Flying a loop with current systems at fixed throttle will result in more current draw on the up side and less on the downside with (relatively) constant rpm (same rpm for a given kv / voltage) but nobody flys loops with fixed throttle - this won't change that (gravity is still involved). As far as the "no feedback / control loop rule" this system isn't really any different than the position feedback system used in servos - a specific control position for a given stick position. Feedback from a pitot tube or GPS speed sensor to a control loop that maintained a speed without pilot control is outside the rule - this system isn't that.
Posted on: 10/6/2011 11:56 AM by Author "EHFAI" in the forum "Electric Pattern Aircraft"
http://www.rcuniverse.com/forum/fb.asp?m=10751571

RE: North Dallas 2011'
I'll be there. BTW, there was concern regarding drought related fire risk, that issue has been resolved and the contest is on.
Posted on: 10/4/2011 8:28 AM by Author "EHFAI" in the forum "RC Pattern Flying"
http://www.rcuniverse.com/forum/fb.asp?m=10747977

RE: Alternate ESC's
I haven't done much research in this area. I'm using the 90A Hacker Comp (Jeti) controllers with the F3A brake. These are the units that were included in the original Hacker Comp motor / controller package. I've used these for thousands of flights with the C50 Comp / Neu / Q80 motors and they've performed flawlessly. As long as they continue to give excellent service I probably won't try something else. The currently available batch of controllers provide output voltage as a function of input pulse width (stick position). Four + years ago I suggested that a controller would better serve our needs (pattern flyers) if it controlled motor rpm instead. So far there's been no significant response to that from the controller manufacturers, but I'm still waiting. With this type system one would set the max motor rpm at full stick to something near what is currently available at the end of a flight (as battery voltage drops). This would provide consistent power relative to stick postion throughout a flight, avoiding the excess power presently available early in a flight when battery voltage is up and (probably) save power for later in a flight. Some might consider this to be very "YS like" in that a given stick position would always result in the same motor rpm - then if we could get the battery to lose weight toward the end of a flight [;)]
Posted on: 9/15/2011 9:23 AM by Author "EHFAI" in the forum "Electric Pattern Aircraft"
http://www.rcuniverse.com/forum/fb.asp?m=10717809

RE: Pattern weight rule - why?
Tim Actually FAI - F3A is AMA class 406. Granted, subject to F3A rules as defined by the CIAM F3A Subcommittee. We have representation on that committee. In fact, many of the "new" things in pattern were conceived by our rep who was chairman of the committee for years. I don't believe that we (AMA classes) have been dictated to by FAI other than by our failure to participate. That's our fault. We've active representation now (Derek Koopowitz) and I assure you that any input to him will receive consideration. The NSRCA has taken an active role (rightly so) in ensuring we have active representation, communication, and participation in both AMA & F3A. Pattern as a whole is much better served by being a part of the global community. That being said, the AMA classes serve well to provide skill development with reasonable opportunities for advancement and competition for the casual competitor. Not everyone has the skill or desire to compete at the top level. For sure, F3A takes more work and costs more than many wish to dedicate to the sport and that's fine, hence AMA Masters being our "destination class". But F3A is the globally recognized epitome of pattern, so it really doesn't serve the sport, or individuals, well for AMA to adopt contrary rules. Certainly there's room in the AMA rules to allow variations in weight, noise, etc. so as to minimize cost and make competition available to as many as possible. We have a Pattern Contest Board that works hard to achieve this. OTOH, it's reasonable that the basis of the AMA rules and practices coincide (and they really do for the most part) with those of F3A.
Posted on: 8/26/2011 1:23 PM by Author "EHFAI" in the forum "RC Pattern Flying"
http://www.rcuniverse.com/forum/fb.asp?m=10688398

RE: Cajun NATS
Brandon I did some checking with Gene, Dave, Jon and the plan is to fly P-13 (only) at both the Cajun Nats & North Dallas contests.
Posted on: 8/20/2011 2:47 PM by Author "EHFAI" in the forum "RC Pattern Flying"
http://www.rcuniverse.com/forum/fb.asp?m=10679096

RE: Cajun NATS
Scott Need to verify the date for North Dallas - Don & club website show it as the next weekend (Oct 8-9).
Posted on: 8/19/2011 2:30 PM by Author "EHFAI" in the forum "RC Pattern Flying"
http://www.rcuniverse.com/forum/fb.asp?m=10677821

RE: Cajun NATS
Todd If you want to upgrade a little there's a new Drury Inn / Wacker Barrel about 12 mi east on I-10.
Posted on: 8/17/2011 11:52 AM by Author "EHFAI" in the forum "RC Pattern Flying"
http://www.rcuniverse.com/forum/fb.asp?m=10674782

RE: P13 - P15
P/F 13-15 are here: CIAM - Meetings - 2011 Plenary Minutes - Plenary Minutes Annexes 7-8. Download the latter, it's a zip file that I couldn't open with WinZip, but it opened fine using Powerarchiver listed on the CIAM site.
Posted on: 7/8/2011 12:25 PM by Author "EHFAI" in the forum "RC Pattern Flying"
http://www.rcuniverse.com/forum/fb.asp?m=10612075

RE: Crowley, LA,
It was so good that we're keeping it a secret!
Posted on: 4/12/2011 7:01 AM by Author "EHFAI" in the forum "RC Pattern Flying"
http://www.rcuniverse.com/forum/fb.asp?m=10458083

RE: Something new from Hebert Competition Designs
Sorry - didn't mean to hijack this thread with the Jenny, a spur of the moment thing. Bryan / Brett will have a bipe in the air a long time before I do. Bryan, the composite fuse front to carry the loads mated to the balsa rear section to save weight is a good idea. Hope you can solve the overall weight / stiffness equation. Retracts went out of favor as much because of long (wobbly) struts as anything - the low bottom wing allows for short struts which makes them practical. Still kinda kool to have those wheels go away!
Posted on: 3/23/2011 4:05 PM by Author "EHFAI" in the forum "RC Pattern Flying"
http://www.rcuniverse.com/forum/fb.asp?m=10418461

RE: Something new from Hebert Competition Designs
I'm going a little different direction with a bipe.
Posted on: 3/23/2011 8:05 AM by Author "EHFAI" in the forum "RC Pattern Flying"
http://www.rcuniverse.com/forum/fb.asp?m=10417568

RE: Hacker Q80 help needed
Burt The motor should not require anymore effort to turn when the prop is tightened. If it does and the wave washer is in place with the flat portion of the aluminum washer forward (toward the collet) and there is spinner clearance, there is some problem that need be resolved by Hacker.
Posted on: 1/5/2011 1:27 PM by Author "EHFAI" in the forum "Electric Pattern Aircraft"
http://www.rcuniverse.com/forum/fb.asp?m=10241752

RE: Neu Gear Box Clean & Lube
Brian I'd expect it to be fine. The high temp limits are a little lower than the Shell Stamina, but no big deal. The moly won't contribute much at the pressure levels in our gearboxes - but it won't hurt.
Posted on: 1/3/2011 6:57 AM by Author "EHFAI" in the forum "Electric Pattern Aircraft"
http://www.rcuniverse.com/forum/fb.asp?m=10236020