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Author Topic: E-36 Pulsar  (Read 4909 times)
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Tapio Linkosalo
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« Reply #50 on: April 16, 2018, 09:40:18 AM »

How consistent is the climb pattern? If it goes wrong, does it start ok and then veer off later? My Puzzle is quite sensitive to battery state, if the power fades then the climb pattern goes off. Large enough battery in good condition and fully peaked ensures good climb pattern.
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Tapio Linkosalo
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« Reply #51 on: April 16, 2018, 11:04:46 AM »


How consistent is the climb pattern? If it goes wrong, does it start ok and then veer off later? My Puzzle is quite sensitive to battery state, if the power fades then the climb pattern goes off. Large enough battery in good condition and fully peaked ensures good climb pattern.

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USch
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« Reply #52 on: April 17, 2018, 02:53:27 PM »

Here a breakdown of weights. As usual there was a surprise and at the end at least 5-6g I could not track down.

Wing 32g
Tailplane 4,8g
Fuselage 110,2
TOTAL 147g

The fuselage can be brocken down into:
fuse structure           27,2g
Cobra 2204           23g
NanoTech 350mAh   30g
ESC YGE 12A               6g
Prop                           4,6g
Timer                   3,5g
Servo D47                   5g
Motor mount           5g
Altis height sensor      2,4g
tail balance weight   3,5g
TOTAL                  110,2g

Fred, I dont know what you mean with southpaw, but I am surely a left-paw  Grin and launch with the left hand. Never got to launch consistently with my right arm (and I dont care).

And now about inconsistent climb and generally about small stability margin. During homework for a new model I run normally the Beuer formulaes for neutral point (NP) and stability margin for the CG. This model has the CG 7,5% in front of the NP. Looks like enough to my experience for fast power models. But the model often bunts during climb and I have to stop the motor via RC, could be underelevated. If the launch goes straight up it might stop in a nose up attidude and stall heavenly, loosing half the height, so again either underelevated or to small a static margin Huh But if one looks on the graph it stalls, but without increasing the amplitude. Turn during the climb is minimal, less than 1 turn in 10 sec, so next time I definitely will try to give 'em more circling power.

Urs

Louis, yes sometimes I play with friends with fast electric boats, but submarines........never  Shocked
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Tapio Linkosalo
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« Reply #53 on: April 19, 2018, 12:22:50 AM »

Never seen a E-36 bunting... so maybe your CG is too far back. Anyway, my experience of trimming Puzzle is that the decalage is the major feature dictating the turn rate of the climb. When I have the model turn too much I move CG aft and reduce decalage, and thus the model turns less tight. So moving CG forward should cure your bunt and also increase the turning rate. Prop side thrust may need to be adjusted too, but I feel that the "loopiness" of the climb induced by decalage is the first order feature defining the turn rate.
 
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« Reply #54 on: April 19, 2018, 04:50:10 AM »

Urs,

Thanks for the weight break-down. A total of 64 grams for the structure is very good. I doubt there is much fat left to work off, other than the 3.5g tail balance weight. An adjustable pylon might eliminate the need for weight at the tail, but the added weight of an adjustable pylon would probably be considerably more. 

The photo of the speed boat brought back memories of a plastic racing boat I had as a kid back in the late 1950s. But mine was powered by a small and weak electric motor---not very exciting. It did develop a leak, turning into a submarine---that was a bit more exciting.

Louis

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USch
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« Reply #55 on: April 21, 2018, 11:40:48 AM »

Went flying..... Grin Grin Grin Roll Eyes

Got up at 5.00AM to be at 7 on the field, pheeeeew.......
To follow Tapio's advice I drilled away 0,5g of tail-ballast to move the CG forward. But the real boomer was a flap to induce more left roll during climb. Still not really consistent as I like it, but sure on the way to it. The second shot of the flap is more to show you our nice flying field rather than the appendice. Third one is the result of the best flight at about 8.00 AM, no numbers to not shock anybody  Wink

Urs
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USch
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« Reply #56 on: June 02, 2018, 12:53:02 PM »

Hallelujah...…

after another month of flying (also winning a comp) and thinking, I tracked down the matter of bunting! A happy man  Grin Grin Grin Cool is reporting.

I had a dream and calculated the force the tailplane has to develop to keep the balance during climb. I knew the speed during climb, about 22m/sec against 4,5m/sec during glide. The force acting on the tailplane works out to be 25g which pull down on the tail boom. So I blocked the fuselage on the working table and put a 25g weight on the tailplane platform. The nice little tail boom flexes near to 5mm  Shocked Shocked Shocked and that means a change in incidence of 0,66°. No wonder the model bunts if it reaches a sufficient speed during climb!

How to stiffen the boom? First thought was to glue a rectangular carbon section, one on top and bottom. But on the finished fuselage it was difficult to fix the rods, keep'em straight and assure that it touches everywhere. So out came the spool of boron thread from which I made up bundles of 5 fibres and started gluing them on the boom with cyano, light and fast  Grin. After 3 tries (15 fibres) on top and bottom I thought to have enough rigidity gain to test the model. Because in the meantime my queer mind had worked out a theory saying that a little flex could be helpfull in the transition  Roll Eyes 

Today I went flying and it worked more or less as I had hoped for. One full turn in 10 seconds and a bit of bunt after 8,5 sec. Heights are always around 180-220m and sink speed about 0,55m/sec.

Urs
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danberry
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« Reply #57 on: June 02, 2018, 06:02:38 PM »

How does it do on the 5 sec motor? Do need to re-trim it to get a transition on 5 secs?
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USch
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« Reply #58 on: June 04, 2018, 02:12:56 PM »

I was so happy I had solved the question that I kept running 10 sec climbs. Mind, I did about 8 flights and recovery's, grass is by now about hip height so doing a recovery from 200-300m is eating your energy at a fast rate.

Next time I will certainly try 5 sec motor runs. I dont see any problems for the transition but that might be wish-thinking  Wink

Urs

PS: how comes nobody from your side of the pond writes what's going on in the USA?
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PeeTee
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« Reply #59 on: June 04, 2018, 02:32:55 PM »

Urs,it all seems to go on Facebook --which I don't use  Roll Eyes
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USch
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« Reply #60 on: June 04, 2018, 02:35:58 PM »

I'm afraid they have to do it without me too, no friend of FB and smart phones, just an old dinosauri.  Cheesy

Urs
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DerekMc
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« Reply #61 on: June 04, 2018, 03:30:10 PM »


PS: how comes nobody from your side of the pond writes what's going on in the USA?

The main E36 developers in the USA don't post on Hippocket or Facebook.  I fly E36 but I'm not a developer of the class. I copy.
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Derek
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« Reply #62 on: June 04, 2018, 03:34:43 PM »

Derek, you may not be a developer but you have one of the sweetest signature:

They fly better when you smile!
 Cheesy Grin Grin Grin

Urs
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DerekMc
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« Reply #63 on: June 04, 2018, 03:43:11 PM »

Derek, you may not be a developer but you have one of the sweetest signature:

They fly better when you smile!
 Cheesy Grin Grin Grin

Urs

Thanks!  I like it Cheesy
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Derek
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« Reply #64 on: June 04, 2018, 03:43:39 PM »

 Grin Grin Grin

I like it!

Peter
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OZPAF
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« Reply #65 on: June 04, 2018, 08:29:24 PM »

Quote
The nice little tail boom flexes near to 5mm  Shocked Shocked Shocked and that means a change in incidence of 0,66°. No wonder the model bunts if it reaches a sufficient speed during climb!

Good one Urs. It bring memories of similar troubles we had with F3B models many years ago. This particular model was turning tightly on the speed course on cold days but in our hot summer sun - the turns were opening up for the same elevator throw.

After estimating the tail loads at speed - we did the same thing - stiffened the boom and the problem was solved. The heat was softening the epoxy on the tail boom, but it was still not stiff enough. We then had a standard test of no more than a 1/4 deg change at the tail for a 1 kg load.

It's a pity so much has moved onto FB -it's not a good place to have long discussions and even though I use it - it is very distracting.

John
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danberry
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« Reply #66 on: June 06, 2018, 02:25:26 PM »

I was so happy I had solved the question that I kept running 10 sec climbs. Mind, I did about 8 flights and recovery's, grass is by now about hip height so doing a recovery from 200-300m is eating your energy at a fast rate.

Next time I will certainly try 5 sec motor runs. I dont see any problems for the transition but that might be wish-thinking  Wink

Urs

PS: how comes nobody from your side of the pond writes what's going on in the USA?


The reason that I asked about the 5 sec run and transition ---

You are apparently going over the top as you approach 10 secs which leads one to think that you aren't up to speed at 5 secs. That would hint that a transition won't be wonderful at 5 secs and the 5 second motor run is all that actually matters in either event.
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USch
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« Reply #67 on: June 06, 2018, 04:45:52 PM »

Got what you mean, Dan. Next time I surely try the 5 sec. climb and report on it. It is quite probably that the models accelerates during at least 8 sec.

In the meantime I ordered some alu-carbon-alu tail booms which should be much stiffer than the Avia Sport Skinny we all use.

Urs
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USch
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« Reply #68 on: June 17, 2018, 10:51:35 AM »

This morning I made a new trip to the flying field to do five second flights and give the batteries some airing, otherwise they might get lazy  Wink

I did only 5 launches because they where so much similar one from the other that it seemed useless to go on. I had absolutely nothing to change, just up and away. Max. height was from 110-117m, very exiting  Grin Grin Grin

Looking at the climbs from below they did not seem to loose  altitude in the transition. Only looking afterwards at the graph's 4 out of 5 have some swoop at the top, but without heavy loss.

At the end of the month we will have a competition and probably I will fly it with 5 second motor runs.

Urs
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« Reply #69 on: June 17, 2018, 08:25:19 PM »

That must be a nice feeling Urs. Boom flex most definitely the culprit of your earlier problems.

Good luck in your contest.

John
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Tapio Linkosalo
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« Reply #70 on: June 17, 2018, 11:43:57 PM »

Wow. To my eye looks like perfect transitions.
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Duncan McBride
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« Reply #71 on: June 18, 2018, 08:21:05 AM »

Double wow.  100+ meters on five seconds is tremendous. I have been trying to build E36 ships as close to the 120 gram limit as possible and use the smaller racing drone motors.  I was happy to see 90 meters on five second runs, but you have raised the bar considerably.  Great work, and thanks for sharing.
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Tapio Linkosalo
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« Reply #72 on: June 18, 2018, 08:53:31 AM »

I do not think that 120 grams is a target to aim too hard for. Several tests and simulations suggest that slight increase in weight does not impact glide much to mention, but if that 10 extra grams for a larger battery gives you 10 to 20watts more power, then that has a big impact on climb altitude. So a strong stiff model, powerful motor and large enough battery is the way to go!

110 meters on 5 seconds. Uhh. Way too much performance. I'd hate to go to 3/5 seconds motor run, but that is what the performance calls for.

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DerekMc
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« Reply #73 on: June 18, 2018, 12:53:02 PM »

Last I heard 120 meters is what Stan Buddenbohm and Ralph Ray are getting so you're among the best. Nicely done!
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Derek
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« Reply #74 on: June 21, 2018, 04:52:15 PM »

As declared in the first post of this topic I wanted to learn and explore the latest technic of carbon D-boxes and carbon strip material for most of the wing structure. That meant also to do more than one model to get the feeling how to dimension the members and keep weight down. Right now I am flying with number 3 ship with a 32g wing which feels comfortable to handle and fly, the complet model is at 147g. If I could build a model with exactly 120g flying speed would diminish by about 0,4m/sec and sinking speed by 0,04m/sec. But the model would be rather fragile I'm afraid. Actually I wonder if it would be worthwhile. So I am weight conscious, but without exaggeration  Wink

Now I am finishing model 4 with a lighter wing of 26g, also the fuselage is 3g less, so I will surely be under the 140g mark, even if the new motor might eat some of this gain. Will see....

Conclusion, better a sturdy and stiff model and some Watt more on the propeller shaft  Tongue  Roll Eyes

Urs
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