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Stig atle steffensen
02-18-2006, 03:00 PM
I've finally bought a "proper" electric sailplane!
the plane is a : Protech Alpha v2.

I have assembled the parts, only the mounts on the rudders left.

My previous sailplane is a Protech Airblade, wich is a really nice one, but not that big.

I think this one will glide well, and will stay longer up in the air with the engine off then my previous plane, it will be really nice :)

i'll sure post up as soon as i get it up in the air, but it might take some days, because of the weather we have here at the moment..

Image is here:
http://home.minlos.no/~stigatle.steffensen/plane.jpg

(Don't mind me, it's the plane :))


[edit]:
i just finished putting it all together,
and i made a wallmount for it, so that i could place it somewhere in my appartment ;)

final image here:
http://home.minlos.no/~stigatle.steffensen/plane2.jpg




.

Stig atle steffensen
02-19-2006, 06:09 PM
soo, this is how the first day went :
i woke up, 09:30, was lying in bed, hoping for nice weather outside,
and it sure was, overcast, with almost no wind at all.

i was thrilled!
i put on some warm clothes, and gatherd my plane, and went out to the field, 1 minute walk from the door.

There i was, in the middle of the field, and i was gonna fly my new glider..
i was a little scared about it, because of how huge it was compared to my previous plane.. but i was hoping for the best.

Full throttle, and away it went, but it seemed like there was something that was not right.. it did not climb like i expected it too, and it seemed to be stalling all the time, even on full power, so i landed it quite nicely, and moved the battery a little more to the front, and tried once more.
Still the same problem, so i landed, and went home.

I then checked everything, and measured the center of gravity, it all looked ok, so out i went again.

This time it was a little better, but it did not seem to get the speed it should, even at full throttle.. but still, i took a couple of rounds around the field, and landed, and tok some more laps, tried to glide some too, but because of the lack of speed it did not go well..
it stalled, and went straight for the ground, but i manage to recover from it nicely, the hardest part of it all was landing it, because it would suddenly loose speed, and it seemed like i had to land it "quickly" so that it would not crash, but then it just soared really nice just a meter of the ground, and it did not loose speed, so i had to try several times to make it right..

But anyways, when i got back after the last trip i had, i found out that the battery i have in it dont have enought Mah, it has 2100, and should be 3000, so tomorrow after work i will go and get a battery that's needed.

so hopefully then it will be easier to fly it ;)
We'll see tomorrow.

Don Sims
02-19-2006, 07:09 PM
stig, how about some more information. The mai of the battery may not be the issue. Give us some more details of your setup. Motor, Prop, Speed control, plane weight, etc.

Sky Sharkster
02-19-2006, 07:48 PM
Hi Stig, I have to agree with Don, if the battery was charged nearly full you should get the power, just not the duration. I'm guessing it's either over or under-propped, not enough thrust would behave the way you describe. Is a 2 cell Lipo?. The number of cells affect the prop size directly, more cells (volts), smaller prop. I know that sounds backward but the more voltage the motor receives, the faster it tries to spin the prop. To get into the right "curve" of the RPM/Thrust range the prop has to be sized to the voltage. For example, if the instructions recommend a 7 cell NiMH (8.4 volts) and you use a 3 cell LiPo (11.1 volts) you would need to down-size the prop, usually a smaller diameter or lesser pitch. Also, with NiMH batteries, usually the first few charges don't deliver full power, they have to be cycled (charged and discharged) a few times before they put out max power. Anyway, let us know about the motor, prop and batteries and maybe we can help!
Ron

Stig atle steffensen
02-19-2006, 09:24 PM
hmm, i'm looking at the package right now, it says:
batterypack 7,2V 1700 mAh

this is strange, because on the site of the shop where i bought it from, it says that it needs:

-7 cell 3000 mAh battery

the battery i used is :

8.4v sc2100 mAh
everything else is standard.. i dont know the info about the prop-size etc..

from my Superstar Ep kit (used the speedcontroller from superstar Ep aswell)..

To be honest i thought that this would work, since the engine are the same on these two models..

and if i'm not completly wrong, the battery i use has more volts, and mAh then the one it says to be used on the package, so it should work, right?

or am i completely stupid?

and to be honest i have not cycled my battery.. because i've just tried it twice, it could be that also then..

Sky Sharkster
02-20-2006, 01:19 AM
Hi Stig, I don't think you're being stupid at all. It's not the first time a company has given a misleading battery (or motor, or prop) size on an airplane package! You mentioned that the recommended battery on the box is 7.2V (let's forget the milliamps for now) the shop recommended a 7 cell (8.4V) battery and you used an 8.4V battery, right? Each cell of a NiCad or NiMh is 1.2 volts. Wired in series, a 7 cell battery is 1.2(volts per cell) X 7( number of cells)= 8.4 volts. It's the same battery! Oh, it has a different milliamp number but that determines duration, not power. There is a little exception to that statement but it's generally true. Put it another way;
More cells (volts), more power.
More milliamps (mAH number) more duration.
Another way of saying it; Cells are like cylinders in a car. 8 cells/cylinders will go faster than 7 cells/cylinders
Milliamps are like the fuel in the tank. 2000 milliamps will run twice as long as 1000mAh.
So no matter how high the milliamp count is, the plane won't fly better, just longer. Also, higher milliamp batteries are heavier, so it might not fly at all!
I believe from the photos you've posted that the glider is about 2 meter wingspan? If that's the case it likely needs about a speed 600 motor without a gearbox. That motor would take (about) an 8 X 4 prop. roughly 200mm x 100mm. I would strongly suggest you try an 8 cell ( 9.6 volt) battery of between 1100 and 2000 mAh size. That size battery will give you 2 or maybe 3 strong climb-outs, then shut it off and glide. 20 minute flights, easy.
now the reasons why the Superstar flew on the same equipment could be, the SS is lighter, has a "faster" airfoil (less drag) a more efficent prop, the plane is smaller, lots of factors. Right now you're trying to get this plane sorted out. I'd start with an 8 cell battery, then once it's flying OK, begin experimenting with prop blade sizes, maybe a little more pitch (200mm x 140mm) and see what happens. Prop blades for folders aren't that expensive, plus they never (well, hardly ever) break so it's a good investment.
Good luck!
Ron

Stig atle steffensen
02-20-2006, 06:59 AM
Thank you very much for the answer, it really helped me understand this.
But if i dont need to buy a new battery at the moment, then i wont, because i need to save money for a litte while, and after what i can understand i've done correct?

But anyways i'll go to the shop, and ask what they have in stock, and what others who has bought the plane has bought with it.

Yes, the glider is about 2m, it's 180cm wingspan, so you guess very good :)

Stig atle steffensen
02-21-2006, 10:08 AM
today it's really nice weather, as soon as i get back from work, i'll empty the battery, and recharge it, and then give it another go.

and as always : i'll post up as soon as i've tried.

Stig atle steffensen
02-24-2006, 03:12 PM
Now i have the biggest smile i've ever had on my face.

i've been trying to fly this plane, and yesterday i crashed it once more, what happend was that i launched it, and then i went for a turn, too soon after i launched it, so it just flipped over on it's side, and spiraled to the ground..

i went back, and fixed it today, i fixed the servo's so that the flaps wont move at theyr "full movement", and that sure helped, the reason why i had it on "medium" at first, was out of a habit, but this plane really responds well to the stick movement,

Today i had the first full flight!

i just love this plane, even though i've hated it for a week..

it soars well (compared to what i'm used too).
and landing it is a dream.

now i just have to learn the tricks that enables me to make it stay up longer :)

the battery-time seemed a little short, but that may be because i was flying with engine on for some time first..

Jason T
02-24-2006, 03:16 PM
Stig,

Congrats on the flight. When you catch some good thermals you will definitely hooked. :)

Sky Sharkster
02-25-2006, 01:04 AM
Nice going, Stig, I'm glad to hear you got some flight time in. Are you using the 8.4V battery? If so, using it a few times may have helped, now it's "broken in" and should give full power. Your flight times will increase as you get used to flying the glider. The important thing during the climb is to not let the nose get too high, too much angle on the climb will create a stall and you'll lose more altitude than you gained. During the glide, try to turn smoothly and without banking the wings too much...wide, slow turns. If a wingtip starts "rocking" or bobbling up-and-down, it might indicate a thermal there, turn back towards the area where the air had some vertical movement and circle there. Soon you'll see the glider go up! That's about as much fun as you can have and the first time you climb without a motor will bring a smile to your face!
Good Luck
Ron

Don Sims
02-25-2006, 01:37 AM
Way to go! Glad to read it's doing a lot better. The guys have given you some good advice.

Stig atle steffensen
02-25-2006, 08:19 AM
thank you for the tips sky sharkster. and you do give good advice.
it's hard to keep it gliding without stalling a bit, because the plane is so responsive! but i will learn :)
and everything you say, is things i now will have in mind today, when i go out. (It's fantastic weather here today).

And thanks to you too don sims :)

Stig atle steffensen
02-25-2006, 11:38 AM
Been out flying all day, and when i put my plane down the last time, it started to get alot of wind, so i'm finished for the day.

It all went really nice, and i'm getting used to how the plane behaves, and the landings, wich i was most afraid of, goes really well, no problems at all.

most of the time i have to try two times, because the plane settles just inches above the ground, and with too much speed for my liking , so i run out of space, and have to give it one more go :)

But i really enjoy it, and i'm happy that i havent broken a single part in the process, and that it now seems to work like it should.

Stig atle steffensen
02-25-2006, 05:42 PM
heh, been flying all day again..
but this last flight ended a little bad..
i was flying inverted, and got near some trees, this was the result :

Images:
http://home.minlos.no/~stigatle.steffensen/wing/1.jpg
http://home.minlos.no/~stigatle.steffensen/wing/2.jpg
http://home.minlos.no/~stigatle.steffensen/wing/3.jpg
http://home.minlos.no/~stigatle.steffensen/wing/4.jpg

it took me 40 minutes of snowball-throwing before i got it down..

nothing else is damaged. i think i'll try to cover with a big sticker i have, and fill the hole with some foam.
but anyways, it's been a great day :)

Stig atle steffensen
03-04-2006, 04:31 PM
soo... it's weekend, and i was out flying yesterday, everything went well.
and today i had 2 flights, the second one was really nice, had it up in the air for a really long time, and as high as never before.

Then i went in for a landing, and the plane was comming towards me, i then dived, and i could not see how fast it went, then i pulled up a bit, and i heard a "SNAP" and the wing was suddenly looking weird, and it was comming down like a rock.



It then hit the ground, it is snow, so no other parts where broken. wich made me happy, because then

i just have to get the one part of the wing to get it fixed. i just hope they'll get it soon.

8204

TeslaWinger
03-07-2006, 02:01 AM
Landings are funny anyway... Since we are near the ground, clutter causes turbulence so we need to fly a bit faster to keep it flying so a gust won't stall it.

On the other hand, if it is going too fast there is so much energy that the plane would be damaged heavily if it made contact and its glide is at it's best at higher airspeeds- just what you don't want! Without brakes of some sort it's hard putting it down right where you want it but practice sure helps! :D

One thing we all learn sooner or later- you can go fast and you can PULL UP- but don't do them both at the same time! I've ripped the wings off gliders trying to escape thermals that wouldnt let go when I made it overspeed! So much for Plan A!

Flying too fast in heavy turbulence will slap the wings together overhead pretty quick too!

Sounds like you were still trimmed too slow. It should be a bit faster than the stall speed, where Minimum Sink occurs, the main soaring speed for the least loss per minute. A few knots faster and it makes it's Best Glide. They both have their uses and once it is trimmed right you can concentrate on flying as smoothly as possible whenever you fly thru a big upward moving patch of air and it starts to get really interesting! Reducing the throws was a very good move. The less we interfere, the better!

It shouldn't be mushing with the elevator trim centered- it takes airspeed to make lift- and it sounds like you were getting closer to proper trim moving the batt forward. An aft CG is a dangerous thing and it will want to stall severely and drop a wing.

A too forward CG will make it fly faster than it should- but it's not nearly as tricky as being balanced too slow! Make small changes and fly each one. Basically, it'll turn nicer if it is back a bit more and glide further and faster when more forward. I always mark the CG point from the plans on the plane so I can change battery pack sizes in the field and always find the right balance point.

Center your transmitter's elevator trim. Put a straightedge on the stab/elevator- check for dead flat. NOW you have a good reference for making CG changes as you move the battery forward a bit more till it flies just a bit faster.

Glad you got some air! It gets easier- and a lot more fun.
Keep that snow handy!
TW

Stig atle steffensen
03-12-2006, 09:31 AM
thanks for the long and good reply teslawinger :)

i got a new wing earlier this week, but i've been really sick, almost had to be taken to hospital, but now i'm better, so i've changed the engine on the plane (it apparently got broken too), and i've put on all the electrics and checked it.
and put on the new wing, so i'm finally going out to fly it again today.