dear all,
after making the f14 nish plane using acrylic sheet, almost a year ago,  i wanted to make a similar one in Depron, since the acrylic one flew beautifully inspite of being heavy.
used the YAP 20 inch f14 plan from RC groups and made this one, using 4mm Depron.

1. 4mm Depron and packing tape.
2. Little screamer park jet and 4.1x4.1 prop
3. Metal gear 9 gram servos
4. 25Amp esc castle creations.
5. Assan receiver.
6.1050maH lipo 3 cell

On the first launch, it torque rolled un-controlably and crashed. The beautiful nose was completely damaged. Still continued to fly after course repair on the field, and did lot of experiments. Finally arrived at 4.1x4.1 prop as the best drawing only 13 amp at wot. The initial prop was drawing about 22 amps. Also noted the best CG position.

After this remade the nose using solid high density thermocol.
Again tried the plane today. it was very nice and beautiful. pl note how critical is to experiment and arrive at the optimum power set up.

thanks for watching.

ashta

the first video

Video taken today after the nose change.


thanks for watching.


ashta

Very nice.  

did some simple decorations on my F14.

after the initial finetuning, it now flies beautifully. Fast and slow, very stable.

The real advantage is that it just takes only about 12 amps at 3cell lipo and wot. (most of the time it flies at 1/3 of throttle) so i can use 1000mah/ 20C lipos safely.

pl see the latest video.


thanks for watching.

What was the initial prop ?  It would be a lesson/example for all on how even small prop differences can cause double the amps draw, there by killing (some parts of) the setup.

initial prop was 5.1x5.1 ( not 100% sure it could be 6x4 also.) and at wot it was about 22 amps. i use little screamer park jet motor.
but the point is as Anwar said, the importance of arriving at the failry efficient prop combination for a given set up. this when ignored, will end up burning lot of watts and puffed cells.

Can we say with confidence that calculations alone is not enough, when it comes to electrical setups ?  For example, in this case, why were you not able to correctly estimate/calculate the amps draw initially ? Was it because the datasheets of something was not available, or it is because that there is always an element of unknown ?  And, a watt-meter is the only sure bet ?

PS: I am trying to make this an even more interesting/educative thread

Calculations is a good starting point and should always conclude and confirm with actual measurement.
few main l factors, that i guess will  affect and deviate from calculated vs actual.
1. KV variations from unit to unit. ( this is the most imp factor esp with cheap chinese motors)
2. Type pf prop used. We. atleast i end up using agin cheap props and they may not behave exactly as per the originals.
hence for me proof of the pudding is in eating and i always measure, adjust and optimise.
ashta

Quote from: anwar on March 24, 2010, 02:59:25 PM
Can we say with confidence that calculations alone is not enough, when it comes to electrical setups ?  For example, in this case, why were you not able to correctly estimate/calculate the amps draw initially ? Was it because the datasheets of something was not available, or it is because that there is always an element of unknown ?  And, a watt-meter is the only sure bet ?

PS: I am trying to make this an even more interesting/educative thread

Quote from: Ashta on March 24, 2010, 06:21:16 PM
hence for me proof of the pudding is in eating and i always measure, adjust and optimise.
ashta

Thats a great wisdom Ashta for newbie like me. From my Chuck/Balsa experience I know kit/plan/Building  building much different from Plug and Fly. But how much surprise to expect is the only thing unknown. 

Would be maiden-ing  my F-22 Raptor this week. Hope your tips help.

thanks ujjwaana.
i was out of sation last three days. hope that you had a great maiden

Astha,

I watched all and could not figure out what adjustment were needed in the first place Call me dumb if you may, but in all three videos, the model flies beautifully (at least that's what it appears to me). So if you could provide pointers on what to look at and why the setup needed tuning it would help newbies like myself.

regards
Pankaj

Pankaj, that makes me the second idiot (Now let's wait for the third!) even I thought she flew beautifully.

Ashta Sir has reached a level of Self Actualisation (Maslow - Hierarchy of Needs). There was once a carpenter who used to delicately carve patterns into the rear panel of an almirah / cabinet even though that rear panel would be against the wall and nobody would ever see it.

When the carpenter was asked why he took so much of trouble to create something that nobody would ever see, know or appreciate, he replied, "I would know and that is all that matters.........."

Ashta Sir .....

Cheers!

VC

dear VC,
Kindly do not praise me so much. Truly i do not deserve it, and pl call me ashta, i apreciate that. And VC if i have an advantage it is only due to the amount of time i might have spent and nothing great about it. It is only a question of time for any body.
to be specific on fine tuning, u will find the following.

1. The plane is trying to do a torque roll during launch in the intitial viodeo.
2. The current with this initial prop was about 22A at 3 cell.
3. After few experiments, the current has been brought down to 12 A and now there is no torque roll tendency at the launch.
ashta

Ashta Sir,

I refuse to call you by your first name. it has nothing to do with your age vis-a-vis mine. It has to do with your knowledge and humility as compared to mine.

Hope you will empathise with me.

Warm regards,

VC

torque roll? is that the way the model banked to the left hand on launch (around 15seconds into the first clip)? How to determine if that is not weather/wind induced?

in the first video u can clearly see the torque roll during the launch, the bmodel banking to the left.
in the second and third video, u do not see this since as u can see the prop is changed, (white prop.)
now to determine whether it is due to wind,  is to check if wind was there during that time.
also if u have done a glide test and if it is gliding well with out any bad tendencies, then it is due to some force caused by the motor/prop.

ashta