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Author Topic: E-36 "Puzzle"  (Read 14305 times)
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OZPAF
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« Reply #25 on: July 13, 2016, 08:17:33 PM »

Thanks for the description of the laying up of your composite booms. I assume that you wax the inside of your mandrel for release - but do use anything else - Vaseline or similar to help the release or is the smooth mandrel sufficient?
John
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Tapio Linkosalo
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« Reply #26 on: July 14, 2016, 12:09:53 AM »

I wax the outside of the mandrel, which is a solid, tapering piece of steel. The wet laminate (fibres and epoxy) is laid directly on top of the waxed mandrel surface, so I do not think there should be any vaseline or other greasy substance - it would only mix with the laminate while laying, make it weaker and not help in the release. The multiple layers of wax are enough to release the surface tension, and thanks to the mandrel being smooth and tapering, the tube can be released once the friction is broken. 
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« Reply #27 on: July 14, 2016, 08:23:52 PM »

Thanks Tapio. Good luck with your E36 flying.

John
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Tapio Linkosalo
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« Reply #28 on: August 03, 2016, 02:52:23 AM »


Did some more test flying the other day, and indeed it seems that the 300mAh 45-90C NanoTech battery is fine for a 5 second motor run (I was able to fly 2 or 3 climbs on the same battery, perfect trim and settle to glide each time), but for 10 seconds the battery voltage drops, and then the model attitude turns more vertical, following a stall on transition.

I ground-tested the one 350mAh Nanotech which I have, and in a static test the motor RPM persisted for full 10 second motor run. So maybe that battery would be better for the longer motor run, even though it is 10 grams heavier (29 vs 19 grams). Maybe it would even gain more altitude despite the higher weight? Unfortunately my RDT is being repaired, so I cannot do more test flights in a few weeks....
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« Reply #29 on: August 03, 2016, 03:59:35 PM »

Thank for your fine report on your model. Concerning lack of steam on 10s with nano 45-90 300mAh, I only have some altimeter readings. And they consistent reads about 25 m less altitude compared to double 5 s readings. (95 vs 165 meters)
So a better battery seems right.
Do you have some logs from these last flights?

Jens
 
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USch
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« Reply #30 on: August 03, 2016, 04:45:36 PM »

but for 10 seconds the battery voltage drops, and then the model attitude turns more vertical, following a stall on transition.

This sentence puzzles me, Tapio. Voltage trop means less power and (normally) a less steep climb. Or does the turn open because of lower airspeed? Opening the turn is also like adding incidence and that could be the cause of a steeper climb. Or not enough wash-in on the right wing?
Just guessing....

Urs
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Tapio Linkosalo
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« Reply #31 on: August 04, 2016, 01:27:10 AM »

Jens, unfortunately I did not have a logger onboard. I need to redo some wiring so that I can connect both logger and RDT at the same time... But the pattern seemed similar as in Sweden, first five seconds tight spiral, then moving to a more loopy pattern. As described below:

Urs, the pattern is somewhat similar than with my "Pimenoff #18" model, with which I also made a few test flights. #18 probably has a bit more dacalage than Puzzle, and also much weaker motor. For the first test I launched it in the same attitude as I launch the Puzzle, and the model made a large loop, had to DT it before it crashed. I then recalled that it needs a flatter and more banked launch, and changing the launch attitude resulted in a nice, if not as steep upward spiral. The Puzzle seems to be about the same. For the first five seconds it goes in steep, but somewhat banked spirals upwards, and if motor is cut at 5 seconds, the model slips right due to the bank and settles to glide without a stall. But with the 300mAh battery failing, after that 5 seconds the climb pattern transitions more to the like of #18 launched too steep: the right bank reduces, model takes a more  straight attitude, and due to the lack of the bank it starts to pull up, vertical or even going to straight, inverted climb. If the motor cuts here and the model is banked slightly to one way or other, it typically rolls and then settles to glide without too much altitude loss, but if it has no bank, then it just finishes the loop and looses quite a lot. I still have not been able to picture, what happens during the latter 5 seconds. Maybe the roll rate to the left is too high and therefore the model is not banked enough to maintain spiral. Looking back at the trimming of my #18, when I reduced the decalage I also had to reduce left thrust of the motor, so possibly reducing left thrust also on Puzzle would help? Or using a battery that does not fade after 5 seconds. Need to try that first!

Another issue that I need to deal with is the glide turn. Currenlty the model glides in very open left-hand turns (almost 2 minutes per one full turn), which probably would not work in thermal conditions. My attempt to add tail tilt for right turn was a failure, it totally spoiled the climb trim. I have not yet tried what impact adding tilt for left turn would have, but will try once I get my RDT working again. Or maybe I'll build another model to test and only start messing with this one when I know more about the trims. I might try another model with rear and above fuselage fin, if that makes a difference in the climb&glide pattern.
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« Reply #32 on: August 04, 2016, 05:35:26 PM »



This reply from John Thompson may nail the problems with constant pattern. Unless safe constant power, no safe climbing trim. ?
I have had some strange experiences with bad cells. The pattern is completely gone.
Per Grunnet has some very high thrusters which only are safe for 6s...

Jens 


   
Re: Blizzard E36
« Reply #86 on: April 15, 2016, 04:28:25 AM »

A couple of years ago I used high power - courtesy of Peter T who does my motor selection - I was getting about the same height 300 feet or so in 5 seconds . !0 second runs were impossible, out of control .
I also increased wing area using a 7 inch chord (with and without undercamber ), total weight I think was in the order of 185 g . I built very rigidly , no carbon booms they flex,( I even tried putting ant the four corners so to speak 3mmx 2 mm longerons on the outside to try to stiffen ) and if they do not, they are too heavy , so regular balsa box . wings Mylar plus tissue .
In fact from memory I built about 3 or 4 of them with various configurations , high , low pylons , lots of downthrust  etc but all were erratic . My final conclusion was that it was the power train that caused the problem .
With a IC engine I would never launch a model without ensuring that the revs (acoustic Tach ) are in the right ball park , models are too touchy when flown to the limits to permit otherwise .
This as of now is not possible ,without a lot of complications ( and what does it do in the air ?) I think with electric motors . I tried same battery , freshly charged , after one run when it is warmed up . Heating battery whilst charging and heavens knows what combinations with other batteries, all to no avail . I also tried different props , the most reliable , but not the ones that got the highest, used small props at high revs , any variation in power I surmise was evened out .
I have not pursued this at all , finding it a bit tame , I am more used to wanting 500 feet at least , in 5 seconds . But every one to their own . I still like to think that I am the quickest ( when checking club mates runs on the ground) one on the watch to ensure a max  4.99 second prop stop , anticipation some call  it, just glad at my age I can still operate a watch . But such small differences can mean the differences between winning and  loosing . This controlling the length of the run needs a bit more sorting out , I think. Such as utilising an electronic timer which is set at 4.9 or what ever , some one should be able to come up with some test device which ensures the same for all ? I know that E36 is popular for it's simplicity but people will always look for advantages to keep interest up, no doubt .  All in all there surely must be a way of ensuring a consistent battery output , but here again maybe not ? Could one have a Controller that ensured the same revs ?  With the marvels of electronics something might exist or be made ?
Do not ask me though about F1Q ,which I foresaw would morph into a powered glider class. Not my style I think ?
John 

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Tapio Linkosalo
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« Reply #33 on: August 05, 2016, 03:05:28 AM »

Yes, I recall reading this this message and my experience with fading power on 10 second motor run seem to confirm the notion that constant power would be needed for consistent trim on a locked power.

John asks about suitable electronics to keep the power constant, and there is, indeed, such devices present. There is a feature called "governor" for speed controllers. This is intended for (RC) helicopters, where the main rotor head speed is kept constant, and rotor lift is controlled by the blade angle. With these beasts, the speed controller is set up to maintain the rotor head speed, measuring the RPM and adjusting the throttle accordingly. Typically the servo signal for the throttle is used to define the desired RPM (so that you can use the throttle to stop the main rotor).

However, there is a catch. For a FF model you would also need the brake to stop the prop after motor run, and in helicopters the break is not needed. Actually it is quite an undesirable feature, as applying brake on a large rotating mass (the main rotor) would cause some damage. So most helicopter speed controllers do not have brake. And hence cannot be used for FF models.

Incidentally last spring when I was building the Puzzle, I ran into a two-man freeware project BlHeli, where two German guys have been developing speed controller software for helicopters and multirotors. Their helicopter main rotor software has (naturally) governor, and just last spring their latest development also includes the brake option for the software. Their software fits a multiple selection of speed controllers based on Atmel processors, the catch is that you need to get programming devices and flash the new software to the speed controller yourself. Takes some tinkering, but can be done.

So my Puzzle uses the Afro 20A speed controller (which is nice and compact to be 20 amps controller) flashed with BlHeli software version 14.6 (the first one with the brake function). But, another catch: the governor can only try to adjust the throttle to maintain the head speed (or in this case prop RMP), but it cannot do miracles. If the battery fails too much, then it cannot keep the RPM. Which is the case with my model, the RPM is fading. One option would be to adjust the target RPM low enough so that the governor only reaches 100% throttle setting at the end of the 10 second motor run. But, this would mean losing potential power and climb speed at the beginning of the flight! So I did not have the guts to adjust my throttle setting ( -> governor target RPM) low enough to keep it constant for 10 seconds on that 300mAh battery. Especially as the trim persisted OK on a 5 second motor run! I tend to lean towards the conclusion that even though the governor seems to be a neat solution for the trim problem, the actual answer for consistent trim lies in a battery that can provide a constant (high) current throughout the 10 second motor run. Once you have such battery, then governor can be used to fine-tune the consistent trim .

Having said that, I think that for a F1Q model a governor controller would be very useful. In Q, you do not have such strict weight limits (as your energy quota increases with model weight, so for a heavier battery resulting in a heavier model, you get compensation by getting more energy allowance). Therefore in Q you could use an overly-large battery and then adjust the energy power with a governor. As a result you could use the same battery, freshly charger or already used and still get similar output power and climb pattern. But this is all academic - as John points out in his message, Q has turned into a powered glider, and like him I find it quite boring. I'm much more thrilled by hot-climbing E-36 models! :-D   
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che
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« Reply #34 on: August 07, 2016, 07:43:05 AM »

To simple me I would have thought that the requirements for a 10s run (UK rules) 'rounds' model is quite different to a 5s run FO model, so why try and get the same model to do both well ? After all we have SBTs in F1A these days specifically for FOs; we wouldn't use a thermal model would we ?

I currently have only one E-36 and it flies a very consistant patten in non-windy conditions (I say that as I have only flown once in the wind and I suspect I wasn't launching it correctly). I've had problem with a high-power motor cutting out my ESC during 10s runs but that was solved with a larger (325mAh) battery albeit at increased weight. It thermals well and it fun to fly.

With a 5s run it doesn't transition well and so my 2nd model will be more suited to FOs and I'll trim accordingly. Of course being a glider guy I have no real idea what the trim will be but I guess it will be interesting to find out. If I had the inclination I'd certainly build a model like Tapio's 'Puzzle' - it seems the way to go for a 5s run.

CHE
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john thompson
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« Reply #35 on: August 08, 2016, 04:34:27 AM »

Che  is right and more folk are doing just that . What I was mainly referring to, was the challenge to trim the "high " powered model for 10 seconds . I found that even on 5 seconds it was inconsistent but about manageable , on the 10 seconds though it was very unreliable , so ,hence with current motors and batteries , I think one has to accept less than 100 % performance to get some consistency .
Yesterday at Salisbury at the SAM1066 gale the usual 2016 weather was in force . 16mph on the ground , much more up higher and very turbulent  ( vintage glider at top of 300 foot line down in 43 seconds etc ) the E36 folk were talking that not only do you need a 5 and 10 second model but also a windy weather one . So now for this simple class you need three models plus back ups .
John
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danberry
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« Reply #36 on: August 10, 2016, 10:32:01 AM »

You need one well-trimmed plane.
Maxes on a 10 second motor run should be a given.
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Tapio Linkosalo
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« Reply #37 on: October 12, 2016, 09:54:37 AM »


Eventually the weather co-operated, and I had a chance to test my Puzzle with the 360mAh battery. In the attached pictures (second one zooms in the climb phase only) you can see the results. The two red lines are with 300mAh battery, the fading of the voltage and power on 10 second climb is easily observed.

The second climb (dashed blue line) was with the same setting as I have flown all summer, it turned out that even with the 360mAh battery the trim was not as it should be, but for the latter half the bank/yaw of the model was reduced resulting in a more loopy pattern, and less-than-optimal pull-out. I reduced the left thrust slightly, and this seemed to improve the pattern, holding on to nice spiral all the way to 10 seconds climb. With the 360 battery the RPM and climb speed do not seem to fade towards the end, so for a 10 gram weight penalty I guess this is the way to go. Actually last summer I managed to pull a decent full 10 second climb from a 300mAh battery, but that was right after topping the battery on a charger. Today, at 5C temperature I was pulling several consistent climbs from the same battery without charging in between. Thus going down the list of flights, the overall altitude reduces a bit, this is due to flying on a used battery.

There is one blue climb that is out of the pack. This was a failed launch (the model turned in my hand to the right when releasing). It climbs at normal speed until 80 meters (but actually going too steep and loopy), at which altitude it pulls to the back and flies horizontal for a while.

One interesting feature was trying to trim the glide turn. So far the model has been doing quite wide open turns, up to 2 to 3 mins for a full circle. Good for calm, but not so for thermal conditions. At some point I tried to add tail tilt for right turn, but this totally messed the climb, the model veered sharply to the right at launch, then went flat and I had to DT it. This time I tried to add tilt for left turn (the model shows a slight tendency for left turn without tail tilt). It turned out that I can add the left tilt without  problem, eventually with tailplane parallel to left center section the model glides in tight left turns, maybe 20 to 30 seconds per full turn. Interestingly, even at such tight turns there is no tendency to spiral in (at least not in the calm). The transition now is much like a catapult glider, from the right bank the model slips right to horizontal straight flight, then the tail tilt bites and turns the model to a left hand glide turn.
 
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Re: E-36 "Puzzle"
Re: E-36 "Puzzle"
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Tmat
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« Reply #38 on: October 12, 2016, 03:20:16 PM »

What about a Thunderpower battery like this Tapio? http://www.thunderpowerrc.com/Products/325-mAhR/TP325-2SR70J
325 mah, they claim 70C continuous discharge and 23 grams versus 30.
more expensive than the Hobby King batteries I know but 7 grams is worth it?

Tmat
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« Reply #39 on: October 12, 2016, 03:22:35 PM »

That is the battery I use. They are hard to find at the moment. Local hobby shop says they are on back order. I bought mine on Amazon but can't find them there last time I checked.
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« Reply #40 on: October 12, 2016, 03:45:28 PM »

I bought some Thunderpower G8 Pro Force 325mah 70C batteries for E36 a few years ago.
These seem to be out of stock everywhere at the moment. But The Thunderpower Rampage 325mah 70C are perhaps the replacement? They are in stock on the Thunderpower website.

Tmat

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« Reply #41 on: October 12, 2016, 06:18:50 PM »

Thunderpower Rampage 325mah 70C

 A quick search has that battery listed on several sites and they are available for pre-order, so they are probably the replacement for the G8 ProForce.
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« Reply #42 on: October 13, 2016, 02:25:31 AM »

Have not tried the Thunderpower, guess it would be worth trying. Then again, the batteries seem to be developing fast all the time. Currently the NanoTech 350 seems to be able to provide the 12A that my motor draws for the 10 second run. Maybe it is time to try more prop... :-)

Honestly I think it would be time to start considering means to limit the power in E-36, the current development is over the roof. The best flights in neutral air, with 1o second motor run climbed to 150 meters (without topping the battery prior to launch nor warming up the battery!), and the model DT'd at 2 mins with over 100 meters altitude. That would equal almost 6 minutes still-air time.
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« Reply #43 on: October 13, 2016, 01:01:09 PM »


I've been wondering - what would happen if I replaced the current APC E 6*5.5 prop with 7*5? The latter has smaller pitch (even measured), but much wider blades in addition to the larger diameter, and (therefore?) the static current draw is higher. Is it just better acceleration, but then lower maximum speed? If so, it seems from the altitude graph that the model reaches constant vertical velocity in just 0.8 to 1.2 seconds, so if the top speed is lower then the 7*5 would result in lower altitude. Hmmm.
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« Reply #44 on: October 13, 2016, 02:17:43 PM »

Tapio, Your graph shows a sink speed of aprox 0.4 m/s which I think is indicative of decent air? I have not heard of an E36 with such a low sink speed in neutral air. That would do over 2 minutes from only 50 meters climb. Unrealistic??


Tmat
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« Reply #45 on: October 13, 2016, 02:42:53 PM »


Honestly I think it would be time to start considering means to limit the power in E-36, the current development is over the roof. The best flights in neutral air, with 1o second motor run climbed to 150 meters (without topping the battery prior to launch nor warming up the battery!), and the model DT'd at 2 mins with over 100 meters altitude. That would equal almost 6 minutes still-air time.

Yes, the top planes are impressive on a 10 second motor run. 5 sec? Not so much. It wouldn't surprise me at all to have the 10 sec. dropped to 7 sec. in a couple years. Problem is most of the US based timers are preset for 5/10/15 sec motor runs so new timers would be in order.  I say give the class a couple more years without any changes. (Dropping the 15 sec time to 10 sec is under consideration in this years rule cycle. I think that is a no-brainer. So no changes after that one Grin) The planes are lots of fun!
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« Reply #46 on: October 13, 2016, 02:45:51 PM »

Thanks again Tapio for your sharing on your design. I'm also a bit shaken about your sink rate.... Your climbs are fine but not records. F1S may be childish but we do own the eagleview! Forget ThunderPower. Buchwald has tested against NT300 (i lab) and they are not worth their price.
See you at Rinkaby next time. And we are working hard to match you!
Rule Changes? At this stage i Europa not needed in my opinion.
Cheers Jens




  
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« Reply #47 on: October 13, 2016, 02:58:35 PM »

Forget ThunderPower. Buchwald has tested against NT300 (i lab) and they are not worth their price.


I've seen this mentioned several times. I don't know about testing but they are quite effective at Lost Hills! I'm going to check and see what Clint Brooks used when he set the AMA record at this summers Nats.
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« Reply #48 on: October 13, 2016, 03:12:46 PM »

@Derik: Personally I have never dared to fly 15 s. Europa is small and the ocean always close. We also fly do F1S here with 10s rounds.  So why not  go for 5 s ordinary rounds and take it from there? With Tapios sink rates I would have 200s or more.
Jens
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« Reply #49 on: October 13, 2016, 03:25:28 PM »

Tapio, Your graph shows a sink speed of aprox 0.4 m/s which I think is indicative of decent air? I have not heard of an E36 with such a low sink speed in neutral air. That would do over 2 minutes from only 50 meters climb. Unrealistic??

Probably some good air. You can see the variation in the different graphs, and the two topmost show slower sinking than the rest, so they are likely to be in some buoyant air.
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