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Author Topic: Let's talk E20  (Read 76483 times)
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Yak 52
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Jon Whitmore



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« Reply #900 on: March 18, 2021, 06:44:47 PM »

That's the correct motor and prop. At least I believe the US rules have opened up now and any 8.5mm is allowed?

Very happy to make you something Urs Smiley
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cvasecuk
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« Reply #901 on: March 30, 2021, 11:37:51 AM »

What happened to the E20 Postal comp?
Ron
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DerekMc
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« Reply #902 on: March 30, 2021, 12:00:05 PM »

What happened to the E20 Postal comp?
Ron


I plan on making an announcement after Easter.  I'm looking at May through the end of 2021. Two divisions: NFFS Rules and E20 Open.

I tried to figure out a way that contestants could report there own scores to google forms (or any online option) but, alas, my computer technical skills are lacking.  If someone knows how to do this and would like to help contact me!

Look for a preliminary announcement next week.
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Derek
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« Reply #903 on: April 02, 2021, 08:44:54 AM »

Derek
I think I have the forms figured out. ill contact you on facebook
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USch
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« Reply #904 on: April 03, 2021, 11:46:47 AM »

Yesterday motors 8520/53500 rev and prop's arrived. Immediately some questions arrived.
These motors are quoted at 53500rev/min. But in the meantime I found the same motor size with 15000 rev's.

  -Do you use this motor with 1 or 2 cell's?
  -Wouldn't it be better to use a slower motor with more torque?
  -The delivery is 2 clockwise (CW) and 2 CCW motors, the difference is visible in the colour code of the power cables, but nobody tells you which is one or the other.
   Do they have different brush directions and/or anticipation?
  -Anybody tried to contain the magnetic field of these motor's? There must be a lot of waisted power!

Next step is building a model, but first I have to finish another project on the building board.

Urs
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OZPAF
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« Reply #905 on: April 07, 2021, 09:06:14 PM »

Quote
-Do you use this motor with 1 or 2 cell's?
I have only used 720's on Scaps up to around 3.5v with plenty of power - so would feel that a single cell would be sufficient - especially for the high reving versions.

Quote
-The delivery is 2 clockwise (CW) and 2 CCW motors, the difference is visible in the colour code of the power cables, but nobody tells you which is one or the other.
   Do they have different brush directions and/or anticipation?

The brushes are of a trailing design and thus the correct rotation is important.
Motor rotation and correct polarity is indicated by the wire color:
clockwise: red +, blue -
counter clockwise: white +, black -

Quote
-Anybody tried to contain the magnetic field of these motor's? There must be a lot of waisted power!
  Interesting idea but would it be worth the extra weight?

John
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DHnut
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« Reply #906 on: April 07, 2021, 11:41:51 PM »

I have used both 1 and 2 cells. The 2 cell was direct drive and the the single cell was for a geared model. Performance is very similar with Ferry 500 on direct drive weighing in at 64 gm and the SAM E20 geared drive at 38 gm and using a Gunther white prop.
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che
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« Reply #907 on: April 08, 2021, 07:18:31 AM »

The NFFS E20 rules specify a 1S LiPo, and most people seem to be following their rules currently. 1S makes sense to me for a simple, lower powered class; we don't want to allow excess power and it to morph in to a smaller E36 class do we ?

CHE
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USch
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« Reply #908 on: April 08, 2021, 01:53:05 PM »

OK, I will use 1 cell as, seems, everybody does.

But can I play with the equipment? Isn't there the fun of model building and flying?

Urs
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Stan
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« Reply #909 on: April 08, 2021, 08:49:25 PM »

The NFFS E20 rules specify a 1S LiPo, and most people seem to be following their rules currently. 1S makes sense to me for a simple, lower powered class; we don't want to allow excess power and it to morph in to a smaller E36 class do we ?

CHE

Too late, with this year's rule changes E20 has become smaller E36. I am not saying that is good or bad.
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USch
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« Reply #910 on: April 09, 2021, 04:27:30 AM »

Too late, with this year's rule changes E20 has become smaller E36. I am not saying that is good or bad.

Could you please explain what you mean?
Not everybody around the world is knowing what NFFS changed actually.
Thanks  Smiley

Urs
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DerekMc
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« Reply #911 on: April 09, 2021, 11:50:52 AM »

Too late, with this year's rule changes E20 has become smaller E36. I am not saying that is good or bad.

Could you please explain what you mean?
Not everybody around the world is knowing what NFFS changed actually.
Thanks  Smiley

Urs

I'm not Stan.  Wink
The original E20 rules per the Willamette Modelers Club used one specific motor and a specific timer.  The original motor is now hard to find so the new rules state a motor size and any timer can be used. The result is more options and more available power.  The original timer used capacitors to set the engine run.  The available energy kind of petered out so you didn't have a hard transition to glide. Most of the new timers have a hard cutoff so you get more power and a full engine run but then transition is trickier.

Pretty much all electric FF classes deal with the issue of quickly increasing power: Motor- battery- prop combinations.  It's part of the fun but it changes the flavor of a simple class like the original E20.
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Derek
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« Reply #912 on: April 09, 2021, 12:44:34 PM »

I must admit to being a little foggy on the changes to USA (NFFS?) rules. There was some info on the F1Q Facebook page a while back if I recall.

As Derek says the original specified motor was a Parkzone 8mm. As I understand it the new rule has opened up to any 8mm coreless and any 1S battery. This doesn't really open the door to E36 style performance as the most powerful 8mm coreless motors still only give maybe 40g of thrust (vs the Parkzones 30g ish IIRC) and there is still a minimum weight limit. These hot motors gobble huge amounts of current though. The Racerstar gives about 35g thrust and is less of an amp hog so it's a nice compromise.

If you want real hot performance then come fly to Peterborough Open E20  Cool we have no limit on power at all  Grin but in reality, trimming ability imposes some self-regulation on this.

Regarding the motor ratings: those numbers are usually no load RPM at the rated voltage of 3.7V rather than Kv (no load RPM per volt). So the 53500 is really 14400 Kv. Is it possible that your 15000 figure is actually true Kv? That said some ebay motor listings may quote the actual RPM with a prop  Roll Eyes   Micro Motor Warehouse are the one outlet that does state motor Kv properly. These are usually between 12 and 18 thousand on an 8mm coreless. It is possible to get higher rated coreless motors for 2 cells but I suspect you would run into diminishing returns with the extra battery weight.

For the Open rule I have found that a 10mm Coreless on 1S 200mAh is a sweet spot for power to weight with 50g or so of thrust and only a couple of grams heavier than the 8mm. A while back I started a brushless set up but didn't finish it. There are some lighter ESC's available now so I should try it again.
« Last Edit: April 09, 2021, 01:04:12 PM by Yak 52 » Logged
DerekMc
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« Reply #913 on: April 09, 2021, 12:55:07 PM »

Here are the NFFS Rules-  I reformatted them to make them easier to read.  Let's see what happens when I copy and paste-

NFFS Rules 2021-2022
Model Eligibility
Projected wingspan not to exceed 20” (monoplane only)
No auto-surfaces except dethermalizers
Model Weight:
Model must weigh at least 1 ounce (28.3g)
Motor Eligibility:
Models must use an 8.5 mm x 20 mm coreless electric motor.
No gear drives are allowed.
Number of Models Allowed:
The contestant is allowed to fly two models in this event.
The contestant must declare a model before attempting the first official flight with that model.
Propeller:
The propeller is not to exceed 2.7 inches in diameter.
Battery:
The battery is a single cell 3.7 volt Lipo battery. There is no limit on Mah capacity.
Motor Timer:
Use of an electronic or mechanical timer is acceptable.
Official Flights and Scoring:
Three flights of up to 90 seconds are scored out of six (6) attempts.
Motor run is 20 seconds.
A motor timer malfunction (fails to shut off or restarts once stopped) is considered to be an attempt
Fly-off flights:
The Motor run is decreased to 10 seconds for the first and subsequent flyoff flights.
The max is increased to 120 seconds beginning with the first flyoff flight and continuing for all subsequent flights.
All flyoff flights are official. No second attempts allowed.
13.10 Attempts:
A motor timer malfunction (fails to shut off or restart once stopped) is considered to be an attempt
A flight of 20 seconds or less is considered to be an attempt
A flight of 20 seconds or less can be used as an official flight if the contestant declares it
« Last Edit: April 09, 2021, 01:12:55 PM by DerekMc » Logged

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Derek
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« Reply #914 on: April 09, 2021, 04:54:30 PM »

Thanks. This is great.

So as it states:

"Battery:
The battery is a single cell 3.7 volt Lipo battery. There is no limit on Mah capacity."

That means that the high voltage 1s Lipo (3.8 V) cannot be used? The way it reads is you can use a 1S any mah Lipo of 25 C, 45C etc., but not high voltage?
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USch
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« Reply #915 on: April 09, 2021, 05:19:40 PM »

First of all thanks for the rule clarifications.

...That means that the high voltage 1s Lipo (3.8 V) cannot be used?...
3,7-3,8V is typical mean voltage and is used to determine any LiPo inclusive HV types.

I wanted to draw your attention to a fact I discovered month ago during a exchange of mails with hobbyking.com. It's about how to define rotation direction of electric motors. All started that I had to buy a motor. Now all drone motors are offered in clock-wise (CW) and counter-clockwise (CCW) versions. Here in continental Europe we define rotation looking from behind the motor, looking in the direction of flight. Looking at the pictures on the HK web page the CCW motors had right-hand threads, the CW left-hand screws, exactly the contrary as expected. So I consulted HK and they confirmed me that they look at the motors from the front. Tonight I scrutinised another web page about the 8520 motors and found that statement:

2.Mearsuring condition
Direction of rotation   viewed from output shaft side


So be aware and use CCW motors for right-hand propellers.

Urs
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« Reply #916 on: April 09, 2021, 08:58:28 PM »

Thanks for the direction of rotation clarification.

Fred Rash
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che
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« Reply #917 on: April 10, 2021, 05:01:47 AM »

I appreciate Derek pasting the 2021 E20 NFFS rules here for all to see. I see these as a good starting point for a world-wide postal event but as a part-time pedant I would like to bring attention to a couple of points :-

1) Battery defined only as LiPo. As others have stated, there are small HV batteries which I've used on E20s and they have better performance than a standard LiPo. I would suggest that the rule would be better if the max. charged voltage was defined as 4.2v. That way you could use HV batteries but have no advantage, and it's an easy thing to process if you're so inclined.

2) The rules state that the motor run is 20s (or 10s for FO) but not when that run is started. So you can (some have ....) tested throwing their model and the motor starting some seconds afterwards - think an HLG with a motor that starts after the throw; the 30m extra is rather useful - just saying. So better to write something like, 'the motor run shall start from release of the model' - it's worded this way in other electric classes this side of the pond.

I would suggest the NFFS pick up on these points for next year.

CHE
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Tapio Linkosalo
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« Reply #918 on: April 10, 2021, 05:31:35 AM »


I fully agree with CHE on point 2. As the small single-cell lipos are mostly intended for micro quad use, they are mostly of High Voltage version. Plus I have heard, that "normal" and HV cells are actually the same stuff, but with different labels. Therefore writing explicitly out that any version of lipo is allowed, but the maximum voltage to charge them is 4.2 volts, make this part of rules specific and clear.

Motor run. My pet subject. I agree that the rules should clearly state that the motor run starts from the launch of the model from fliers hand. But the other end is also unclear, as it is for many other motor classes (FAI included). As motor timing for a small model flying high is problematic (motor sound is low, and seeing the prop stop difficult), my suggestion is that the motor run can be statically verified by the timekeeper before the flight, and motor run end is defined as the time when the prop stops.

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che
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« Reply #919 on: April 10, 2021, 06:45:50 AM »

I'm glad Tapio picked up on the 'ground timing' point - it's the only practical way to do it, so write it in the rules.

When your E20 is at 100m after 20s (they all are, right ?) you can't hear anything but the mooing of the cows and the naying of the horses in these parts.......

CHE
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USch
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« Reply #920 on: April 10, 2021, 06:50:41 AM »

I am for rules which are clear and controllable. Like:
"Hand launch with running motor(s)"
Everybody can check that, no judge necessary

But not
"max. charged voltage defined as 4.2v"
Rise the hand who's prepared to spend his day checking competitors charger if set to 4,2V , instead of flying   Roll Eyes

It is questionable if HV LiPo's are really all that better.
At first glance they seem better because you use them with the same motor and propeller, so 0,15V has the motor running at higher rev's! If you would try to fit a slightly larger or higher pitched propeller on the "low voltage" cells the difference would nearly disappear. It's the WATT that counts....

Urs
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Tapio Linkosalo
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« Reply #921 on: April 10, 2021, 09:23:07 AM »

But not
"max. charged voltage defined as 4.2v"
Rise the hand who's prepared to spend his day checking competitors charger if set to 4,2V , instead of flying   Roll Eyes

It is questionable if HV LiPo's are really all that better.
At first glance they seem better because you use them with the same motor and propeller, so 0,15V has the motor running at higher rev's! If you would try to fit a slightly larger or higher pitched propeller on the "low voltage" cells the difference would nearly disappear. It's the WATT that counts....

I do not think that the statement of maximum voltage in the rules would be for people checking each others chargers. I think in the Free Flight, the rules as rather followed mandated by the code of honour, in other words you follow that as you do not feel that winning by cheating would be worth it. After all, there are many other similar rules. For instance, the rubber weight in P-30. You could easily use 12 grams of rubber, without anyone noticing, and have you ever heard of anyone going aroung and weighting other peoples motors?

Rather the aim of such wording would be to state out that using HV lipos at over 4.2V is not according to the rules. Without writing it out there would be the evergoing ambivalence whether HV lipos are allowed or not.

It is the watts that count. They are the current multiplied by the voltage. Thus HV lipos @4.35 volts translate into more watts.
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raggedflyer
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« Reply #922 on: April 10, 2021, 11:51:35 AM »

But the 4.35v is not for long. Total motor input power during the motor run is the next parameter to consider. Slippery slope!
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DerekMc
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« Reply #923 on: April 10, 2021, 03:17:49 PM »

Th last few posts show how hard it is to formulate electric rules for free flight that will last over time.  The variables are many!
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« Reply #924 on: April 10, 2021, 03:59:01 PM »

Come on guys; this is not a World Championship. We know what the rules mean. Let's just get out there and have fun.
Ron
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