SEN 1617

Table of Contents - SEN 1617


  1. Q Interpretation ?
  2. Jim Parker on LDA
  3. News?

Q Interpretation
?

 
Extracted from the rules
b) For models without energy limiters the motor's energy in watt-sec over
the motor run is calculated as the measured wattage multiplied by the motor
run.  A freshly charged battery (4.15 to 4.2 volts per Li cell, 1.2 volts
per NiCad or NMH cells) should be used. When the motor has reached full
power, wattage is measured using a commercial wattmeter via 3.5 mm male and
female bullet connectors furnished by the contestant.

I have a question related to the rule above: I read between the lines that it implicitly assumes that the whole motor run should be made with "full power", however the rule fails to say that. So, if I want to make my motor run with constant power, therefore throttling the motor gradually up during the climb to compensate for dropping battery voltage, how is my power measured? Or, if I have a somewhat overpowered power train in the model, and still want to stick to full 20 second motor run, and therefore set my "throttle" to 80% for the entire climb to meet the required power level, how does my power measure then?

Looks like it is perfectly OK by the rules to use partial throttle throughout the flight, but your energy budget just cannot be measured then?



-Tapio-



More Jim LDA

Below are the reports on 2 more of Jim Parker's LDA development sessions, together with words of wisdom from assorted friends.  Originally on FB - with a  couple of pictures


Jim Parker LDA—Training Session #4, SWR Contest Eloy Arizona Jan 2012

Friday afternoon arrive, per forecast strong breeze—flew standard short that I tested last week at LH- all fine. Flew LDA with lower stab OLA angle. Noticeable less pull—more like a strong conventional model. Feeling more comfortable.

Sat morning- breezy so test fly short standard and LDA—not enough confidence to fly LDA in contest. By first round start, breeze droppedp so test flew standard long—landed in mud. First round, solid air-- RDT did not work but I did not know it- could not find model- returned to line for round 2.

Mickey Furman arrived—official M&K representation conference being charged to the factory. Short model ready and positive air so set it up- Mickey asked if set for Max—“Yes, all my models are set for 4 minutes". Good launch, solid air, DT at 1 minute—instant memory of resetting DT at LH windy test last weekend---

Notice that LDA and LSD are only one letter different. Both result in extreme focus on one item and the rest of the world does not exist? I quickly get over the drop—now I can fly the LDA is competition!

Mickey was of great help providing accurate feedback of each launch. He is awaiting his M&K LDA delivery here in the USA when Sergei and Mikhail come for the Feb contests.

Well, three dropped flights with the LDA—bummer. First two are late in the air with OK launches—high by conventional model standard but the model bores thru the air doing 30 sec circles. In LH, calm the circle 45-50. Third launch is poor—did a 150m sprint down wind chasing Brian V’s thermaling model—the legs did not have the stuff—LDA’s must have speed! Starting to think that I my revile Per's brick. Last flight I put in better air and got my first LDA max.

Sat night I'm thinking of the Roland post World Champ comment-- this model (Black Mamba?) good in nuetral to positive air but not as good a standard model in down air. My model would not "Rock and Roll" in light lift--it would not turn down wind and find the thermal. I determined that one of the trim knobs I have not turned was the inboard wing wash in (wing wiggler-WW). In Session #2, I mistakenly made a WW change from which I learned that on tow, wash in works the same as on conventional models. That night I decreased the glide WW and rudder setting.

Sunday morning the nice Eloy days we so love. I forgot my F1H so was able to fly the LDA. First flights looked much better. Mickey provided feed back on my bad habit of releasing the line too late—a tendency I have. Decreasing the glide rudder and wing washing position showed direct coloration to wider glide circle and better glide. The rudder is maybe 1 mm right of center. I have not measured the wash in. On the last flight, slight breeze, overcast sky I made a 96 m launch and did 5:23sec. Haven’t made the 100m-360sec club yet but closing in.

Mickey had a sample M&K LDA program. Comparing launch times:
M&K Parker
Rotate .38 .25
Cruse 1.18 1.70
Bunt 1.14 .75
Total 2.70 2.70

Interesting the totals are the same. I think I have greater stab movement so more distinct rotation and bunt. Andrew Bauer (Ken’s dad) did a NFFs sympo years ago and looked at hard bunt and soft bunts- his conclusion was there is very little height difference—1m better for a hard bunt—this was obviously for the conventional “60-70m” bunt models.

 

 

Chris Edge Jim, my numbers for comparison/interest : Rotate 0.33, Total Cruise 1.2, Total Bunt 1.3, Total Total 2.83. Rotate time came down with stiffer boom. Sections : BE9050 to BE6527 + BE8017. CG 52% ish, hook 12-13mm ish. CHE PS Should that read 'LSD camp' ?

 

Mickey Furman FYI- Programming LDA under LSD might result your model to RIP. PS, it's OK to LOL...:-)

 
Charlie Jones it enlighten Steven Jobs to greatness!
 
Javier Abad Jim, i am getting ready for the LH LDA camp
 

Chris Edge I think they re-planted in at Lost Hills, along with a shrubbery. CHE

 

Jim Parker The photo is from Eloy Arizona-- about 300 miles east of LA, near Phoenix AZ. Home of two of our 36 AmCup contests. Previously crop land- was very large and empty but farming restarting in the area. Also home of a now a speed trap waiting for anxious flyers driving to the field.

Thermals, JIM

 
 
 
 
 

Jim Parker

LDA- Training Session #5 LH, Jan 28,2012

50 F, slight breeze

Spent less time changing the program and more time flying and observing the glide. I use new 200lb spectra line-- this did slow the model down, had to reduce cruise time 0.04 sec.

Also a fine straight rudder and bit more OLA rudder to get the model turn slightly to the right for better recovery. Best 102 m with slight stall at top, 6:50-- very happy. Per last report, reduced rt wing wash in and glide rudder. On this flight the model "wandered"- at one point doing 180 degree left turn, average circle was 60-80 sec. Altimeter showed fairly linear decent. Lift thru 11:00 was very light. On other flights however, even with the wandering setting, the glider would speed up and tighten to 45 sec and descend quickly-- 2 such flight with 95 m launch did 3:00 and 3:30 flights. Hard to compare with no other models in the same air. With my current set-up I have the Roland Syndrome-- at least how I understand his explanation-- in neutral to positive the Black Mamba has very good glide (equal to convention long model) but in even slightly negative air the LDA glides much worse. My observation, again base on my single model flights, the LDA does not seek out light lift.

Can't wait for the LDA federation to arrive in Lost Hills to see if others have solved this issue.

I'm right 100 flights-- all the more respect to Sir Roland.

We've had some rain at lost Hills and have some green grass started. Thanks to Jeff Ellington and his crew for the remove of tumble weeds and mowed grass--the field is in great shape. Praying we get another high pressure zone off the coast during Fab FAI FF Feb and more heavenly flying conditions..

Tony Mathews Watching my friend Jama's M&K model I never saw the behavior that you mentioned. Perhaps the Icarex covering helps??

o   .

Chris Edge Magic angle ................ CHE

Javier Abad Jim,still using the standard medical tape @70% on the wing? and thinner one on the stab?

Jim Parker Javier-- wing has one this thin turbulator, .18mm
Stab has two thin, stacked, .36mm

After getting Tony's post that perhaps the rough surface (Ixcarus) top cover would solve my speed sensitive (tighter circle) problem, I regretted not trying the clear laquer spray that I had packed away in the car. I'll try it next.

Thermals, JIM

Tony Mathews You may lose a few meters in potential altitude, but I think you'll find that the rougher surface will make your glide much less sensitive to

Javier Abad Tony and Jim, we need to compare our results using the clear sparay lacker, mi results looks quite smooth......please bring the can to the field :-)

Chris Edge Would be very useful to track the height changes with modifications to surfaces; I see a Sympo paper in all of this. I'm writing someing for the GB forum on my experiences with these machines (eg effects of stiffer booms and stiffer tails) which will be out later this year


News ?


HI John [i'm not John]

 

Is there any good news about the rubber

 

Regards

shmulik

.....................
Roger Morrell