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Author Topic: Having a change of heart regarding F1Q  (Read 694 times)
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Starduster
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« on: February 19, 2019, 01:44:02 PM »

So, I know that I've been trash-talking F1Q for a while now ("Oh, it's too hard!" "I'm not smart enough")

But, I'm sort of a beta tester for Dan's Timers new Energy Limiter enabled timers.

As you are all are probably aware, I am not a fan of bought airplanes. I enjoy the designing, building and testing of an airplane. I design as much as I can, but I also will build from short kits.

I've started a flight-test program for the new timers, and the first thing I had to decide is what kind of airframe to use?

I flew F1B for a while, but when it became very clear that one must buy the latest and greatest composite airframes to be in any way competitive, I kind of gave up F1B and that's when I started flying electrics.

So, looking around the shop, I've got a few "Old School" F1B's hanging around. Why not use those as my "Flying Laboratories"? As F1Q is not quite as weight conscience as F1B (in fact, there is no weight rule for Q) converting a B to a Q might be just the thing. In fact, after adding all the electronics and the battery, the closer I can get to 550g the better.

What I have decided is to use one of my old Tilka wings, and a Bob White Wake wing. I've built two new fuselages and Horizontal stabs, but they are basically a modified Tilka Fuselage and fin.

I also have a short kit for a Tube Steak III and that wing is a bit bigger (area) than the Tilka or Bob White. Thinking about building that wing.

I actually converted one of my Tilkas to Electric R/C a couple of years ago, and it flew really well.

I have ordered and received two Sidus Energy Limiters. And just last week, I got the two prototype Dans timers.

The hardest part for me was actually trying to figure out where to put all of the electronics in the fuselage. I will post some pictures a little later showing how I figured it out. The weight and balance seems to be pretty good, with a fairly short nose moment.

I started experimenting with the timer/EL/motor/ESC/battery set up, and it is all fairly easy to hook up the whole thing. With the current set up, the total weight is coming in at about 380g. With the power set up, that is giving me about a 18 second motor run. Not bad, but just for giggles, I set the EL for 1650j and got almost exactly 30 seconds motor run. (30.5) So, once I start the flight-test phase, after I get the airplane trimmed, I'm going to start experimenting with adding ballast until I get to 550g. I think it will be a very interesting experiment to see if adding ballast and gaining that much motor run will be worth it.

Along the same line of thinking, I could use the same logic as full-size sailplane's use: for light-lift conditions, remove the ballast and use a shorter motor run. In strong-lift, use the ballast and get the longer motor run.

Now I'm starting to think that with a little more experimentation, one could design and build a big airplane (say, maybe, 25-35% larger than a F1B) and build it right to 550g and really have a competitive airplane.

BTW - Just for giggles, I tried the EL set for 1650j and put it in my Pimenoff #18 and all I got was 8.3 seconds at full power.

I do have one question for you Electrical Engineers out there:

I had been thinking that since the Dans timer has a throttle setting, I could simply reduce the throttle setting and I could get a longer motor run with the same amount of joules. After trying this on the bench, this is not the case. At 100% throttle, I got 18.2 seconds, at 50% I got just a little better, 19.1. Why is this? Is the ESC eating up the energy?

This might turn out to be a fun flying season!
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USch
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« Reply #1 on: February 19, 2019, 02:33:14 PM »

After trying this on the bench, this is not the case. At 100% throttle, I got 18.2 seconds, at 50% I got just a little better, 19.1. Why is this? Is the ESC eating up the energy?

Oh yes, the ESC are not very efficient when switching on-off to reduce actual power output. I dont have exact numbers, just  the fact.

Urs
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BG
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« Reply #2 on: February 20, 2019, 11:52:27 AM »

Have you been following developments on the F1Q/F1s facebook group? The Israelis are leading the world in Q these days. Sitton just won two out of the three world cup events in Lost Hills flying large F1Q models using f1B prop blades on a geared motor. models look like a cross between F1B and F1E ships but with very light wings.

B
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« Reply #3 on: February 21, 2019, 04:31:39 PM »

Following on BG’s comment there is a very good paper by Omri Sirkis on the Israeli approach in the 2017 NFFS Sympo  report. Well worth reading.

Ray
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« Reply #4 on: February 22, 2019, 09:56:00 PM »

Not wanting to rock the boat as I'm not a competitor or too savvy about F1Q or E36 for that matter.   I'm wondering why the free flight community is looking at energy limiters in F1Q rather than the altitude limiters that are being used in the ALES sport of R/C. Please forgive my even mentioning that sport on this forum. It just seems as though using an altitude limiter that can be set for 100, 150, or 200 meters depending on field conditions  would be easier than attempting to limit power output if the end goal is to keep the sport from becoming a money pit for the latest prop, motor, battery combination.  Im sure the units could be built for other altitudes or time limits other than 30 seconds if there were enough demand.  I'm not sure how accurate the units are from one to the next.  It just seems like limiting the altitude of the launch would in the end be easier.  Perhaps this approach would go a long way toward allowing gas and electric power to compete together and cut down on the many events at contests while increasing the number of flyers in each event. Please forgive me for speaking of any elephants in the room, but I need to be enlightened.  If its noise the electrics are lacking we could mount a playing card slapping against the prop.  Many thanks to anyone taking the time to set me straight.  Not wanting ti hijack this thread but it seemed like a good place to ask when I saw energy limiters mentioned Wayne
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« Reply #5 on: February 23, 2019, 02:14:36 AM »

I've brought up the idea of altitude limit several times.  It doesn't fly because its too different from traditional Free flight practice. The goal is to get as high as you can for the class your flying.  Altitude limit is completely opposite.  Personally I think it could be cool.  Slap a honker of an engine on the plane. Launch it straight up so that it is going full tilt when the altitude limiter cuts the engine.  Coast straight up for as long as possible then bunt into the glide.  It would be pretty awesome...
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« Reply #6 on: February 23, 2019, 10:08:26 AM »

Many thanks for your concise and straight forward answer.  I fear that the havoc being unleased on the commercial air traffic by a few carless drone flyers may lead to the sky's being taken away from model air crafters.  Hopefully we free flight folka will remain free to soar to unlimited heights.
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Tmat
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« Reply #7 on: February 23, 2019, 12:05:47 PM »

I've brought up the idea of altitude limit several times. 
I know and I've mentioned and liked the idea for years. Power flyers hate it. Too bad as I like the concept.

Tony
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Starduster
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« Reply #8 on: March 11, 2019, 01:58:44 PM »

I've brought up the idea of altitude limit several times.  It doesn't fly because its too different from traditional Free flight practice. The goal is to get as high as you can for the class your flying.  Altitude limit is completely opposite.

I agree. FreeFlighters tend to be a pretty conservative bunch.

Personally I think it could be cool.  Slap a honker of an engine on the plane. Launch it straight up so that it is going full tilt when the altitude limiter cuts the engine.  Coast straight up for as long as possible then bunt into the glide.  It would be pretty awesome...

However, I don't agree with this. I think that rather than this approach, designers would go down the path of a VERY slow climb, ideally a climb that lasts for the entire duration of the Max, then DT at the prescribed altitude. So, there would be no glide time at all. Essentially an outdoor F1D event.
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Tmat
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« Reply #9 on: March 11, 2019, 02:25:28 PM »

However, I don't agree with this. I think that rather than this approach, designers would go down the path of a VERY slow climb, ideally a climb that lasts for the entire duration of the Max, then DT at the prescribed altitude. So, there would be no glide time at all. Essentially an outdoor F1D event.
Probably, so you make the engine run a max of 10 seconds and that solves that. Either the altimeter cuts the motor or the timer cuts it before the altitude has been reached. Or any engine run that you think is reasonable.

Tmat

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Starduster
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« Reply #10 on: March 11, 2019, 02:46:06 PM »

Probably, so you make the engine run a max of 10 seconds and that solves that. Either the altimeter cuts the motor or the timer cuts it before the altitude has been reached. Or any engine run that you think is reasonable.

Tmat

Yes, but by limiting the motor run, it turns into a F1C type event.

This is why I'm changing my mind about F1Q. The idea of an energy limiter really opens the door to new design ideas. Though the current designs are definitely leaning towards bigger airplanes and slower climbs, I could also see a branch going the opposite way and flying a smaller airplane with a screaming climb. I think a really fun design challenge for F1Q right now is to see if you could design a high power/weight ratio airplane and still manage to get a 30 second motor run. Say, something like a 500 in2 wing, coming in right at 550g. I think the right design could be OOS at 30 seconds.
« Last Edit: March 11, 2019, 03:08:01 PM by Starduster » Logged

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« Reply #11 on: March 11, 2019, 02:52:07 PM »

Don't see that anyone mentioned the maximum motor run for F1Q. I think it is 35 seconds no matter what the model weight.

Louis
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« Reply #12 on: March 11, 2019, 03:07:05 PM »

Don't see that anyone mentioned the maximum motor run for F1Q. I think it is 35 seconds no matter what the model weight.

Louis

Yes, but the max motor run is 30 seconds

(ref: https://www.fai.org/sites/default/files/documents/sc4_vol_f1_freeflight_18.pdf , page 40, paragraph 3.Q.2 )

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Tmat
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« Reply #13 on: March 11, 2019, 03:16:07 PM »


I could also see a branch going the opposite way and flying a smaller airplane with a screaming climb. I think a really fun design challenge for F1Q right now is to see if you could design a high power/weight ratio airplane and still manage to get a 30 second motor run. Say, something like a 500 in2 wing, coming in right at 550g. I think the right design could be OOS at 30 seconds.
Doesn't work that way. With 550 grams you get 1650 Joules of energy. Divided up over 30 seconds that's not a lot. This will climb slowly no matter the wing area. And if the wing is small, it will glide rather brick like no?
To get a fast climb with 1650 Joules you need a short motor run. Which you can do. It's just not likely to be competitive with a slow climbing efficient airplane of F1A size.

Tmat
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« Reply #14 on: March 11, 2019, 04:09:43 PM »

Starduster,

Thanks for the correction---too lazy to dig through rule books.

Louis

PS

For F1Q I could see the advantage of having a fast-climber for windy rounds and a slow climber for hopefully calmer fly-offs. The extra 20+- seconds added to the climb might be the winning margin, assuming equal glide rate of sink.
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« Reply #15 on: March 12, 2019, 02:54:26 AM »

After trying this on the bench, this is not the case. At 100% throttle, I got 18.2 seconds, at 50% I got just a little better, 19.1. Why is this? Is the ESC eating up the energy?

Something not right here as power is proportional to voltage or current squared. ESC losses should be a low percentage. I would measure the motor current and rpm at 50% and 100% and go back to basics. Could the Energy Limiter be misreading at reduced throttle settings?
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« Reply #16 on: March 12, 2019, 04:47:12 AM »

For F1Q I could see the advantage of having a fast-climber for windy rounds and a slow climber for hopefully calmer fly-offs. The extra 20+- seconds added to the climb might be the winning margin, assuming equal glide rate of sink.

In F1B, people use (about) the same climb duration for calm and wind. Why would F1Q be any different?
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« Reply #17 on: March 12, 2019, 06:05:36 AM »

What does 50% throttle actually mean? The number settting is fairly meaningless. You have to adjust it until you get the current/revs you want.
Ron
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« Reply #18 on: March 12, 2019, 07:05:26 AM »

Tapio,

The slow climber F1Qs, at least the ones I've seen, climb at a constant speed. This could cause problems if the flight line is pulled up close to a tree line in windy conditions. I've seen a few struggle a bit after launch.

Almost all F1Bs now use the same motor length/number of strands regardless of wind speed. But I can remember back in the late 1970s/early 1980s using much longer, lower torque motors in "calm air" Wakes. Besides being a logistical nightmare (different motors for different models), the long-run models were rather helpless (and hopeless) in wind & turbulence.

To me, the big advantage of the slow climber F1Q would be the extra time gained in the power portion of the flight. If a fast-climb F1Q gained enough altitude compared to a slow-climb model to make up the extra 20 seconds or so difference in motor run time, then the fast climb approach would be work for both rounds and fly-offs.

Did you see Sergei Vorvihvost's article in the October 2018 Free Flight Quarterly? He claims a 20 to 30 meter advantage for the geared model with F1B type prop using 3J per gram. "...in a fly-off with 2J per gram, the higher efficiency of the geared propeller is an advantage that makes the geared motor unbeatable."

Using Sergei's numbers, it looks like the geared model would be the best choice for all flights in decent weather conditions. Perhaps it would be good to have a "wind & storm" direct drive model in the box.

It's great to have an event that allows a variety of approaches.

Louis
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Tapio Linkosalo
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« Reply #19 on: March 12, 2019, 08:29:29 AM »

Yes, getting clear of ground turbulence may be an issue. But in similar fashion to F1B, you could adjust your motor power in F1Q to start at higher power, and then throttle down. As a matter of fact, in the old days one of my countrymen did just that, started at higher throttle, and after initial acceleration powered down just to maintain climb speed - he did straight climb pattern then, though.

On the other hand, I have seen people take the reverse approach. Start at low power setting just to get the model safely off hand, and then after a fraction of second throttle up. They claim that it helps to avoid initial crashed due to bad launch attitude - the model is settled in flight before more power is applied. I do not know if that really is a viable way to go.

   
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« Reply #20 on: March 13, 2019, 07:38:42 AM »

Tapio,

Thanks for reminding me of all the things you can do with electric power that you can't do with gas or rubber.

Louis
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« Reply #21 on: March 13, 2019, 12:46:10 PM »

Tapio,

Thanks for reminding me of all the things you can do with electric power that you can't do with gas or rubber.

Louis

That is one of the really cool things about electric classes. Lot's to explore!
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« Reply #22 on: March 14, 2019, 12:35:55 PM »

Another (silly) question for you EE Types:

Due to the location of the batteries, I need to install a switch between the battery and the ESC or the Limiter. I usually don't use switches on my other electrics, preferring to simply un-plug and plug in the battery, but in order to do this on my two test airplanes, I would need to remove the wing(s). I don't mind removing the wing to change a battery, but that's kind of a hassle to do after retrieving the airplane after a flight.

So, here's the silly question: does it make a difference if I install the switch on the negative or positive lead? I can't imagine why it would make a difference, but I'm not an electronics guy, so...

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« Reply #23 on: March 14, 2019, 02:12:58 PM »

No, it does not make any practical difference. But normally you would interrupt the black, negative wire.

But I would never put a switch in the power circuit because of the high resistance eating away a lot of power. You could make a sort of emergency stop as used on electric power-boats. It works with a jumper wire and 2 connectors, I tried to sketch it. 2 supplement connectors are still much less resistance than 1 switch. I build it with a little piece of PCB board, about 12x6mm with the copper removed halfway through and 2 female connectors soldered to it. The connectors stick out the thickness of the pylon and are flush with the outside. The PCB is then glued to the inside of the pylon. When you take off the wing to change the battery you connect one wire to the board and the other to the ESC. Once ready you connect the jumper wire from the outside. Actually you can leave the jumper connected to one connector and only close the circuit when you are ready to fly. There can be a lot of different solutions using basically the same principle.

Urs
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Starduster
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« Reply #24 on: March 14, 2019, 02:25:37 PM »



But I would never put a switch in the power circuit because of the high resistance eating away a lot of power...

It works with a jumper wire and 2 connectors,

Another example of the great information that can be found in this forum!

Of Course! A simple jumper wire set up! I love this, a simple, elegant solution.

Thanks so much, Urs!
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