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RE: Designing a new pattern model - 9/4/2010 6:49 PM   
MarkGrabowski


 

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quote:

ORIGINAL: Alex Voicu

Hi Claude,

At the moment i am only able to work during weekends, which makes the progress a little bit slow.
Anyway, sheeting the fuselage with balsa is a tedious job and i think it took longer then assembling all the lasecut parts. I tried different techniques, like planking (covering with narrow balsa strips) and bending balsa with water just to see which one works best. Pictures will follow in a week or two.

The fuselage is 160mm wide and 345mm tall, but i've been playing with a slightly different canopy shape that will reduce the height of the fuselage to 338mm. The rudder is about 400mm tall.

Alex, is the balsa you used on the top, curved parts of the fuselage the same thickness as the flat sides? If not, how thick is that balsa compared to the sides...
Mark

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RE: Designing a new pattern model - 9/4/2010 11:46 PM   
Alex Voicu


 

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quote:

ORIGINAL: MarkGrabowski
Alex, is the balsa you used on the top, curved parts of the fuselage the same thickness as the flat sides? If not, how thick is that balsa compared to the sides...
Mark


Hi Mark,

Initially i used 1.5 mm balsa for all areas. Anyway, i recently stripped all the balsa sheeting and re-covered the whole fuselage. Flat sides are still 1.5mm, but this time i used 2mm balsa for planking the curved areas to compensate for the final sanding.

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RE: Designing a new pattern model - 9/5/2010 12:03 PM   
highfly3D


 

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Status: offline 		that is lot of work..

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RE: Designing a new pattern model - 9/7/2010 10:07 PM   
MarkGrabowski


 

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Status: offline 		Alex, I really like the way you've blended the vertical fin and the top of the fuselage without resorting to the large chunk of balsa carved and sanded to fit. Could you please post a few more photos of this area, if it's not too much trouble? Thanks for sharing in this build!
Mark

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RE: Designing a new pattern model - 9/7/2010 11:45 PM   
Alex Voicu


 

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Status: offline 		The fuselage is now film covered so i can't take more detailed pictures, but i found a few old images. I hope it helps.

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RE: Designing a new pattern model - 9/9/2010 12:53 AM   
Alex Voicu


 

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Status: offline 		Well, it's finally (almost) ready to fly. What's left to do is set the wing and stab incidences and program the radio.
It's just a prototype and i'd like to fly it before our local contest, so i didn't have time for pretty color schemes. It's a little overweight, but removing the spinner will make it legal. I will post more details the following days.
Some pictures, in higher resolution than usual:



























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RE: Designing a new pattern model - 9/9/2010 1:44 AM   
wildwillie3


 

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RE: Designing a new pattern model - 9/9/2010 4:04 AM   
rt navi man


 

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Status: offline 		I am a newb to pattern flying, I am a machinist by trade and I must say have enjoyed watching your building skills at work

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RE: Designing a new pattern model - 9/9/2010 4:10 AM   
Rendegade



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Status: offline 		Gorgeous Alex, outstanding!

Just needs two more things: a left and a right wheel pant!

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RE: Designing a new pattern model - 9/9/2010 7:41 AM   
MarkGrabowski


 

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Status: offline 		Alex, be sure to post a picture of your equipment installation without the canopy...
The plane looks wonderful, I hope it flies straight and true!

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RE: Designing a new pattern model - 9/10/2010 6:56 PM   
Gregg G


 

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Status: offline 		That's amazing Alex. Your accomplishment is so impressive. Your very talented.

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RE: Designing a new pattern model - 9/10/2010 11:07 PM   
guille2006



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Status: offline 		AMEN!!!!!

What a plane!!!!
Tell whatever but Pattern ship doesn't need so meny colours and strips everywhere for being nice... they're outstanding just white, and this plane is even nicer in all white.
Again, congratulation Alex; great job!!!

Guille

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RE: Designing a new pattern model - 9/16/2010 11:20 AM   
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Status: offline 		Can't say anything alex....Superb !!!

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RE: Designing a new pattern model - 9/16/2010 9:43 PM   
Alex Voicu


 

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Status: offline 		Thanks everyone for the kind words, i really appreciate it.

Wheelpants would look great indeed but i need to save weight where it's possible. I attached a few shots of the interior and the weight list, so please let me know if you have any ideas for saving weight.

The Scorpion S5525-225kV motor is very powerful, on a fresh set of batteries and using a 19x12 APC propeller i had 3600W on the wattmeter so i had to limit the throttle curve at 92%. I'm still getting 3200W but at least the current dropped to an acceptable value during static tests (~82 A). The ESC is a Castle Creation ICE 80HV and the batteries are Rhino 4900's lightened by removing the shrink wrapping and cutting the wires short.

Edit: so far i have 3 solutions for the weight problem:
1. remove the spinner - easy fix, but spoils the lines of the plane;
2. build a lighter cowl - the one in the pictures is one of the first attempts, i can probably save at least 20g building a new one;
3. buy HV servos and remove the regulator (saves 38 g but it's quite expensive).


fuselage..........................1039
cowl...............................125
canopy.............................117
rudder..............................70
gear+screws........................144
wheels+axles........................50
taiwheel assy.......................20
left wing..........................327
right wing.........................325
left stab...........................96
right stab..........................96
wing+stab tubes.....................80
motor..............................690
ESC.................................98
10s battery pack..................1200
receiver............................25
rx battery..........................55
spinner.............................45
propeller...........................70
rudder servo+carbon horn+screws.....70
elevator servos (2)+screws..........60
aileron servos (2)+screws..........120
control rods........................22
regulator...........................38
servo leads.........................60
wing adjusters+screws...............21



total.............................5063


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< Message edited by Alex Voicu -- 9/16/2010 11:11 PM >

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RE: Designing a new pattern model - 9/16/2010 11:10 PM   
MarkGrabowski


 

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Status: offline 		Alex, this is a prototype and earlier in this thread you mentioned that you did not use the very lightest balsa so all things considered, your finished weight is very respectable. Maybe you can save a few grams next time you layup the composite parts? I believe you said that the plywood used in the frame was 1.5mm regular plywood... does someone (even if it's from overseas) make 1.5mm lite ply? Go test fly it and enjoy the fruits of your labor! Once you get the incidences right and make any decalage changes to minimize mixing, you could certainly offer short kits for sale to help recoup your development costs....
we are entering the winter building season and the marketplace is crying out for a reasonably priced, well-engineered pattern kit!!!

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RE: Designing a new pattern model - 9/16/2010 11:46 PM   
iflyrctoo


 

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Status: offline 		Very nice plane Alex.

You could get it under easily with a different motor such as a Plettenberg. Did you run a single 4 wire lead back to the elevator servos instead of seperate servo leads? That would be good for 10 to 15 grams. A Jaccio regulator is 15 grams instead of 38 (Not sure it's available where you are). You are close. I'm sure with a little tweaking you will get it under.

Joe Dunnaway

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RE: Designing a new pattern model - 9/17/2010 5:01 PM   
guille2006



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Status: offline 		In our UAV we changed battery in order to save some weigth too; we had TRU RC 3P 4S (11.1@16A) weigthing 1216g and now we went to a custom pack: 3P 3S (11.1@15.8A) which weights 1068g.
Maybe you can give a similar approach to your system; I can give you more detail on monday if you have interest...

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RE: Designing a new pattern model - 9/17/2010 8:32 PM   
NJRCFLYER2


 

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quote:

Edit: so far i have 3 solutions for the weight problem:
1. remove the spinner - easy fix, but spoils the lines of the plane;
2. build a lighter cowl - the one in the pictures is one of the first attempts, i can probably save at least 20g building a new one;
3. buy HV servos and remove the regulator (saves 38 g but it's quite expensive).


Alex:
I will save you 26g on that regulator for free. Send me a PM with your mailing address and I will send you one Tech-Aero PLR5-E programmable regulator to replace that 38g regulator that you now have.



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RE: Designing a new pattern model - 9/18/2010 12:03 AM   
Alex Voicu


 

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Status: offline 		Thanks everyone for the tips, it's really helpful.

I couldn't find 1.5mm liteply anywhere. I can get 3mm liteply here, but weight is the same as 1.5mm regular ply. A kit version is in the works, just need more time. Should be at least 150g lighter, so weight shouldn't be a problem.

A lighter motor or lighter batteries would solve my weight problem, but i have to be careful before changing them because CG will be pushed further back. CG is currently at ~30% MAC, so i have to think about that too. It's also quite expensive to make such changes.

Thanks Ed, that's a very generous offer but following the advice i got here on PM and from local pattern pilots, i already ordered a Powerbox Digiswitch today.

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RE: Designing a new pattern model - 9/18/2010 12:29 AM   
wagen017


 

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Status: offline 		Alex, I don't know how particular they are in Rumania, but here weighing planes is not something done at our national contests. Although there is a 5kg(+1%, so 5050grams) rule, it has sort of been decided by the flyers we don't really push for this. So I would just go and fly & enjoy!

Volkert

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RE: Designing a new pattern model - 9/18/2010 12:38 AM   
Alex Voicu


 

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Status: offline 		Well, our national contest is very strict about the rules. Weight and sound checks, dimensions, battery voltage, everything is done by the book.

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RE: Designing a new pattern model - 9/26/2010 7:06 PM   
Alex Voicu


 

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Status: offline 		I finally took the model out to the flying field for the maiden flight yesterday. The conditions were not ideal (overcast, strong crosswind) but even considering the limited practice i had this year (only 6 flights with a foamie), i just couldn't wait any longer.

Take off was short and all the trim needed was 1 click of right aileron and 1 click of up elevator. First flight was a little shy, but by the third flight i was confident enough to try a knife edge loop. It went very well, probably just needed to add throttle sooner in the second half. With more practice it will be perfect.
Knife edge pulls a little to the belly, but i completely expected that having the CG so far back. Downlines are very slow, and even if the entry speed is higher the model actually decelerates on its way down. I forgot to switch to rudder high rates for most of the stall turns, so i can't comment on that at the moment.

I attached a few pictures from the flying field and 2 videos. First one shows the maiden flight, so it's a little boring and for the second i tried to gather more aerobatics from different videos. Don't expect too much from these videos, i was just flying around trying to get used to the plane.






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RE: Designing a new pattern model - 9/26/2010 8:19 PM   
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Status: offline 		Hello Alex

Great job.
I thought the name was Hypnose !
regards

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RE: Designing a new pattern model - 9/26/2010 9:42 PM   
David Bathe



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RE: Designing a new pattern model - 9/26/2010 10:06 PM   
apereira


 

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Status: offline 		Looks awesome, very good speed.

Congratulations!

Alejandro

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