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Author Topic: Let's talk E20  (Read 69337 times)
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OZPAF
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« Reply #800 on: August 01, 2019, 05:05:38 AM »

Good luck with it Ralph. It will be interesting to see how a possibly faster climb will pan out overall.

Happy recuperation Jon! Fast shut off with prop brake - sounds neat!

Folding props would be nice.

I must have a go at one of these but Super CAP models have grabbed me recently.

John
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Ralph B
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« Reply #801 on: August 10, 2019, 09:16:17 AM »

I just returned home from the Nats in Muncie. I flew the Thermite for the first time upon my arrival in Muncie on Aug 4th. I'm very happy with the model's performance. The climb and power pattern are outstanding. Glide seems to me to be on par with my other E20 models. I came very close to loosing it on one of the short motor run trim flights. I did not noticed that the DT line had gotten pushed up off of the worm gear on the actuator and was actually on the motor shaft rather than the gear. It was high enough after an 8 second motor run that it was finding some air. When the DT did not release I thought I would never see it again. Fortunately it was soft lift and after going up and breaking out of the lift a couple of times it finally came down as did my heat rate!  The next time I flew it on Tuesday the winds had picked up and I felt the glide trim needed more work. I flew the E20 competition on Tuesday evening with one of my other models.

The E20 event this year was very competitive with four pilots making the fly-off round. Attendance was up from last year and we all had a very fun time.

Ralph 
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FF Bruce
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« Reply #802 on: August 10, 2019, 04:26:47 PM »

Ralph, good job. E-20 is always one of our most popular events here in the Northwest. Our club sponsors the Nats event. It is a fun little event and a gateway to the larger electric classes. I'm still flying the first E-20 used to set up the rules it's about 6 years old with hundreds of flights, still wins ever so often. So glad you had fun,that is what it is all about.   
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Ralph B
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« Reply #803 on: August 10, 2019, 08:56:39 PM »

Bruce:

Thanks to you and your club for sponsoring the E20 event at the Nats. It's the highlight of the modeling year for me. I think it's the perfect entry level event for someone thinking of getting into free flight or someone who is returning to the hobby after many years away. I always try to encourage anyone that shows interest in my models to try an E20. I don't think there is another class with a better return for the time and money invested. The current generation of E20 models are capable of delivering really great flying performance. I hope the class continues to grow and becomes an official event. Many thanks to the Willamette Modelers Club for sponsoring the Nats Event.

Ralph
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Yak 52
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« Reply #804 on: August 11, 2019, 09:06:04 AM »

By George I think we've got it!  Cool

https://m.youtube.com/watch?v=VF7NxtasXfg
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OZPAF
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« Reply #805 on: August 12, 2019, 03:17:57 AM »

You might just have at that Jon. Were you able to test the brake as well? Folding props next?

John
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Yak 52
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« Reply #806 on: August 12, 2019, 09:47:42 AM »

Cheers John. It doesn't look much but a lot of work has gone into getting it to this stage. The prop brake works on the bench test in that the prop stops dead. Without the brake the prop will freewheel for half a second. The real test will be in the air testing: in moving airflow.

This will be an 8 second timer for UK Open E20. I'm wondering if there would be any interest in a 20 second version for the US competitions? I've been making some timers on a commercial basis recently. I know Luke N makes them at the moment but I understand he does it in his own time to support the class.

Thanks for the info on the US Nats - sound like it went well. Anyone got any pictures?

Jon
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OZPAF
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« Reply #807 on: August 12, 2019, 08:10:20 PM »

Sounds great Jon and ahh- tempting !

Hope you'll be up and about soon.

Cheers

John
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Yak 52
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« Reply #808 on: August 19, 2019, 08:11:32 AM »

Just finished a flyable version of the dead stop/prop brake Open E20 timer – it weighs 0.8g with connectors and gives 8.4 seconds on my 10mm coreless motor. Shown below with standard Ferry 500 timer (which weighs more!) Pretty much what I’ve been working towards all this time and about as small as I can go without etching a proper PCB (next project!)

I also have a 20 second version  Wink
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OZPAF
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« Reply #809 on: August 19, 2019, 09:00:28 PM »

That's impressive Jon especially at that weight.

John
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atesus
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« Reply #810 on: August 23, 2019, 03:45:45 AM »

This is my new Zenaida E-20. I had designed it some time ago but had not built it. I built it last week in a hurry and got to fly it for the first time at the NW Free Flight Champs in Tangent Oregon - with not much success in the contest, I must admit Embarrassed. Later on though, after adding quite a bit of downthrust, the climb pattern got much better and things started looking up. Still more trim work is needed. I also have to solve the tissue detachment problem from the undercambered ribs. The ribs are cut out of 1/32" balsa which don't offer much surface for strong adhesion. I'll try recovering the wing with pre-shrunk tissue and see if that solves the problem. The overall weight is 31g.

I'm using a K&P adjustable nose button's location ring (visible in the third picture, also see the last picture) as motor mount. It is a perfect fit to the standard motor. This is a piece that's usually left behind after each K&P nose button I install on a small model.

Best,
--Ates
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Yak 52
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« Reply #811 on: August 23, 2019, 04:01:59 AM »

Really like that Ates!

What airfoil did you use? And what timer?

Jon
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OZPAF
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« Reply #812 on: August 23, 2019, 04:42:20 AM »

Very neat Artesus! These things are starting to get to me!

John
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Yak 52
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« Reply #813 on: August 23, 2019, 05:22:10 AM »

Oooh go on John - you know you want to  Cool

There's lots of scope for aerodynamic improvements for you too  Grin
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OZPAF
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« Reply #814 on: August 23, 2019, 05:54:51 AM »

You're right Jon. I'm particularly partial to the idea of using thin low drag airfoils. Hmmm!

Are you up and about yet? I hope that ankle has recovered!

Cheers
John
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atesus
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« Reply #815 on: August 23, 2019, 11:08:11 AM »

Thank you gentlemen!

Really like that Ates!

What airfoil did you use? And what timer?

Jon

Jon, the airfoil is a modified MID103 but don't ask me how I picked it and what I modified from the standard MID103 Grin. I remember I was playing with XLFR at the time, half understanding a quarter of the things Cheesy. The timer is the standard Willamette timer. The white prop is something that came in a batch of props I picked up on Ebay, and performed well based on some rudimentary testing I did at the time on props and batteries for E-20. I should find those results too.

Best,
--Ates
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atesus
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« Reply #816 on: August 23, 2019, 12:26:51 PM »

About 4 years back, I had run some rudimentary static thrust tests on the E-20 propulsion package that I had acquired to see what effect the battery type and propeller used would have on performance. I have no idea how the results will translate to dynamic (e.g. in flight) performance but I thought it was interesting to see that the battery type didn't make much of a difference but different propellers differed significantly in thrust generated. The best propeller I tested (in terms of total impulse - basically the integral of thrust vs time curve) was a unit I acquired alongside many other propellers on Ebay, and I don't know who makes/sells it. I have a few more of those left.

Next I have to complement these results with flight tests though I suspect a different model would like a different propeller. For what it's worth, here are the results.

http://oaklandclouddusters.org/resources/Documents/Articles/In%20the%20Workshop/E-20_prop_battery_study_AG082319.pdf

https://youtu.be/PcFPVVtWI98

Best,
--Ates
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Yak 52
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« Reply #817 on: August 23, 2019, 04:40:45 PM »

Very interesting findings. I have done some similar testing but with a variety of motors and measuring max static thrust because we can use anything in the Open E20 PMFC rules.

Static thrust is one of those problems - ie knowing how much you get in reality  Undecided I think you need to build a wind tunnel next  Grin

Ankle is progressing well thanks John - some way to go but much improved.

Jon
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Yak 52
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« Reply #818 on: August 25, 2019, 05:54:45 AM »

Ates, have you considered the Parrot/King Kong 65mm props?

Jon
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atesus
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« Reply #819 on: August 25, 2019, 01:31:01 PM »

No Jon but I'm ordering some to test. Thank you. While researching that I came across a few more alternatives, I'll order those too.
--Ates
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Yak 52
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« Reply #820 on: August 27, 2019, 11:06:28 AM »

Hi Chaps,

Attached are a couple of pics of my finished Open E20 model for PMFC rules.

33g all up with 51g static thrust from a DD 10mm coreless.
The timer gives a dead stop at 8 seconds and brakes the prop in the glide.
Glides across the lawn were encouraging (I missed the lawn entirely!) Just off to trim it at Ferry now – thunderstorms permitting…

Jon
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atesus
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« Reply #821 on: August 27, 2019, 01:47:21 PM »

Very nice Jon. I like the way the propeller is protected. I need something like that too.
--Ates
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Yak 52
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« Reply #822 on: August 28, 2019, 02:38:01 AM »

Hmm. Folded my wing on the first power flight  Roll Eyes I had too much L thrust and some unintentional stab tilt and the model did a big graceful left arc and lawn dart  Undecided
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OZPAF
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« Reply #823 on: August 31, 2019, 02:46:39 AM »

That was bad luck. at least you know it was too much left thrust now Smiley

John
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DHnut
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« Reply #824 on: August 31, 2019, 03:51:27 AM »

Jon,
       I have purchased 2 E20 kits and motor and timers from SAM at the Nats and will be encouraging Don Spray to join me in a build. I will keep all informed of progress. T\ravelling back from Sweden today so will miss Flying Aces.
Ricky
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