A simple build Plank with KFm4 section.. with WOW! factor.. Called it the "Nifty" - Page 3 - RC Groups
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Jul 11, 2009, 05:12 AM
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davereap's Avatar
Rained off here today as well.. what do you use for streamers?

Sorted a motor, and cut a 9x5 down to 7.5x5, I just hope it fits my motor mount

edit added
I doubt you will find a faster build than this, and I now think that the build can be simplified with a bit of thought towards the motor stick fittings onto the wing... how yet I am not decided.
Last edited by davereap; May 06, 2010 at 06:51 AM.
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Jul 11, 2009, 06:22 AM
RIP Azarr - "Old age is not for sissies"
Azarr's Avatar
Quote:
Originally Posted by davereap
Rained off here today as well.. what do you use for streamers?

Sorted a motor, and cut a 9x5 down to 7.5x5, I just hope it fits my motor mount
We're just using standard crepe paper rolls ~ 2" wide. The Muncie combat group cuts them in half on a band saw, but we haven't bothered. We have 19' of one color with a 1' contrasting color at the end and just tape them on with packing tape. Seems like we hit planes more than streamers, hence the search for simple, quick, cheap

Azarr
Jul 11, 2009, 06:54 AM
Onward through the fog.
Cybernaught's Avatar

Plank Build in PI...


Cybernaught checking in:

I finished my Plank in about 3 hours from start to finish but it took from 6:30am to almost 1:30pm with visitors and receiver problems.

I'll upload a few construction pics with comments and if I maiden tomorrow, as I plan, I'll upload the video too.

I use cheap white poster foam for 90% of the build because that's what's available here in the Philippines I make tips, skuff guards and bumpers from a form of EPP that is used for wall insulation, after removing the silver stuff from one side. I KFm4'd the wing at 50% and used no wood in the build at all. FG reinforced tape is used to cover the front half of the wing and my foam sheets are 1/2" thick by 2'x2' square. Size is 24" x 12" and all three pieces come from one sheet. 2x11 7/8 elevons are added to the 24 x 12 basic wing and make the size overall 24" span by 14" chord. That about 336 sq in or 2.3 sq ft.

I use Popsicle sticks for control horns and Hot Glue exclusively for fastening. Very thin colored tape makes the aesthetics less boring and it works best if applied over a layer of the FG reinforced stuff. The quality of materials available here is quite poor as a rule and I have learned what works for me through trial and error. Stainless steel wire is available for pushrods and I order what radio gear, motors clevises etc, that I need, from HobbyKing in Hk.

My planes are built from what's in my head not from plans and they always morph as they grow into being. Nothing turns out as originally planned. That's just my way.

Cross your fingers that the maiden goes OK. I have a feeling that this will be a handful to fly!

Great addition to the hanger, Dave. Thanks for your efforts.
Steve.
Last edited by Cybernaught; Jul 11, 2009 at 07:02 AM.
Jul 11, 2009, 07:07 AM
gpw
gpw
“There’s no place like Foam”
gpw's Avatar
Cyber, Great build using "What you got".... Looks Super !!!!

Thinking a 3:1 Aspect ratio would be less roll sensitive ...hmmmm???

All the planks we flew were a handful.... Couldn't take your eyes off em' for a second... But were loads of FUN !!!
Jul 11, 2009, 07:09 AM
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davereap's Avatar
Azarr.. just tried the 2208-21 with a cut down prop ( 9x5 cut to 7.5x5) I am getting static test results of 10300 rpm and 1/2 throttle gives enough power to go up vertical..full power and its a job to hold by one wing, whilst I measure the revs...Max power static is at 15.5 Amps and 170W which is a bit much for this motor which is quoted as a 13A Max.. another 1/2" off the prop might help but I will fly it as it is now and hope the inflight power drain is slightly less

To compare the other motor using a 9x5 prop was giving 24oz thrust at 8400 revs..again at 15A

I am going to leave the 2208 on and try it. the speed should be better and theres more than enough power for this size model

GPW ....Its not roll or pitch sensitive I just have wide elevons and loads of movement...just reduce the aileron movement for a slower roll... my ups and downs were all 35mm when just moving the stick on one axis only.. reduce to 20mm and it wont twinkle quite as fast.. If you make a higher aspect ratio you might loose the ability to get the fast roll... mind you 20 seconds with a knife and you can get what AR you want..
Taking your eyes off a model...bad idea.. did that a long while ago, ended up trying to fly someone elses plane whilst mine was going down

Steve ..you can fly the thistle well, this should fly very similar, just go on low power for a while..
Last edited by davereap; May 06, 2010 at 06:53 AM.
Jul 11, 2009, 04:19 PM
Onward through the fog.
Cybernaught's Avatar
Quote:
Originally Posted by gpw
Cyber, Great build using "What you got".... Looks Super !!!!

Thinking a 3:1 Aspect ratio would be less roll sensitive ...hmmmm???

All the planks we flew were a handful.... Couldn't take your eyes off em' for a second... But were loads of FUN !!!
Hey gpw,
It's all fun! When you want to fly you'll find a way to put things together.
thank goodness for HK suppliers!

It's 5am and windy. Sky just starting to get a bit light now. Why am I up this early on a Sunday morning? If it's too windy to fly I may take the Plank to the flying site and try some glide testing Here I have some trees blocking the wind down low.

Dave,
I figure I'll probably launch on 1/2 throttle or so I have a feeling that this will do well with some adjustment and a BW motor but i'll fly it the way it is first to get a feel for what I'm getting myself into. Putting on a BW will lower the weight even more with the small battery and that setup pulls the Thistle very well. The plank is a lot lighter than the Thistle. Between 3 and 4 oz difference!

When there is wind before daylight it's usually not a good sign. Cross your fingers guys...

Steve.
Last edited by Cybernaught; Jul 11, 2009 at 04:39 PM.
Jul 11, 2009, 06:47 PM
RIP Azarr - "Old age is not for sissies"
Azarr's Avatar
Well, I got the basic building done, still need to add the equipment. I had a 27" piece of depron just asking to be used so I ended up with an 85% version. 27" span, 13.5" chord, basic wing is 6mm depron with 1/4sq balsa and 3mm depron for the step. CF rod on the leading edge for "protection" during combat.

Azarr
Jul 11, 2009, 08:10 PM
flyin' fool
goldguy's Avatar
Another nifty design, gotta try one for sure. Got a 12mm innie and some tiny servos, so goin' small.
Jul 11, 2009, 09:00 PM
Onward through the fog.
Cybernaught's Avatar

Change made...


I swapped the 2822 for a BW motor and made minor changes to the servo-arnm/pushrod setup. Power is less but it went to 285g for an AUW of 10oz matching your 4.3 oz/sq ft, Dave. Balance is dead on 20% with room to move it either way. The Plank should fly slower than my Thistle Mk4 and be more aerobatic. I may even get longer flight times since it should fly on less throttle. Throw may be too much though. We'll see. I think this is a good mod. I'm feeling good about it and for some reason it doesn't look quite as ugly as it did before. Hmmmmmm

Way too much wind and rain is threatening. No idea when it will maiden.

Pix below. We're going to have a fleet of these things before it's over. too bad we cant get them all together for a "Plank-fun-Fly".

Mabuhay,
Steve.



Edit:
This thing goes together so fast it may be the world's first scratch-build "ARF".
Last edited by Cybernaught; Jul 11, 2009 at 09:14 PM.
Jul 12, 2009, 03:06 AM
Registered User
davereap's Avatar
Azarr.... nice and bright.. I would recomend the addition of the tape covering, in your case use clear tape....it stiffens and makes everthing more damage resistant...fully covering the elevons will keep them from flexing too much.. I know from experience that a hard hit and sudden stop will tear a wing from the back going forward to the step...I also know how hard you have to hit a tape covered wing to put it out of action...
I am waiting on the rain to stop so I can try the 2208-21, and its just starting to brighten up now.( 9.10a.m here) The smaller higher reving prop should give me about 1/4 more top speed.. the numbers revsxpitch give a theoretical top at 48mph..actual, I havnt a clue

steve...I cant wait for the flight, have your up rates at about 25mm up and down ...and down rates at 15mm or there abouts.. and when you get it sorted I bet you put back that more powerful motor..
Jul 12, 2009, 06:35 AM
Jack
jackerbes's Avatar
Here is the progress report on my 32" x 16" FFF build.

It is glued up, and partially taped. Next will be to insert the 3/8" square stick for the motor mount in that hole in the leading edge, then get the nacelle built and glued to the bottom of the wing.

I made the spars from 1/4" x 3/8" basswood because that is what I had on hand. I also slid some 1" +/- FFF filler strips down in to the wings after they were glued up. That induced a slight curve in the KFm strips and also added some filler inside the wing so that there is less give in the strips when you grip it for launching. I am a side arm frisbee toss launcher too, just like Dave. It is the perfect launching method for all my wings.

The wing is at 235 grams as you see it in the photos.

I had to run out to the LHS yesterday afternoon and pick up a motor mount, the E-flite EFLM1915 was the choice. At $4.99 for one motor mount, that ran the material bill up from about $2.00 for tape and foam to $7.00 or so. This is turning in to a major investment. :>) If I were more patient, the GWS GWEMM28T plastic mounts at about $1.50 each would have worked as well and helped with the costs.

This a really an easy build and applying the tape was a no brainer because it was nearly all straight flat runs. I cut the elevons and hinged them with the colored tape as I was applying it. The black bottom will be very visible from the ground, I like that.

The Mainesoon rains came back during the night, no rush on getting this finished up...

Jack
Last edited by jackerbes; Jul 12, 2009 at 06:41 AM.
Jul 12, 2009, 07:07 AM
Registered User
davereap's Avatar
A nice sunny day now with rather strong winds, and a field full of footballers... oh well they will have to go home sometime... what a cheek footballers on the football pitch when I want to fly
Last edited by davereap; Jul 12, 2009 at 07:14 AM.
Jul 12, 2009, 07:53 AM
Onward through the fog.
Cybernaught's Avatar
Quote:
Originally Posted by jackerbes
Here is the progress report on my 32" x 16" FFF build.

It is glued up, and partially taped. Next will be to insert the 3/8" square stick for the motor mount in that hole in the leading edge, then get the nacelle built and glued to the bottom of the wing.

I made the spars from 1/4" x 3/8" basswood because that is what I had on hand. I also slid some 1" +/- FFF filler strips down in to the wings after they were glued up. That induced a slight curve in the KFm strips and also added some filler inside the wing so that there is less give in the strips when you grip it for launching. I am a side arm frisbee toss launcher too, just like Dave. It is the perfect launching method for all my wings.

The wing is at 235 grams as you see it in the photos.

I had to run out to the LHS yesterday afternoon and pick up a motor mount, the E-flite EFLM1915 was the choice. At $4.99 for one motor mount, that ran the material bill up from about $2.00 for tape and foam to $7.00 or so. This is turning in to a major investment. :>) If I were more patient, the GWS GWEMM28T plastic mounts at about $1.50 each would have worked as well and helped with the costs.

This a really an easy build and applying the tape was a no brainer because it was nearly all straight flat runs. I cut the elevons and hinged them with the colored tape as I was applying it. The black bottom will be very visible from the ground, I like that.

The Mainesoon rains came back during the night, no rush on getting this finished up...

Jack
Nice looking build so far, Jack.

She should be easy to see with the black tape on it. Hey, regarding your "Mainesoon" Does it look anything like this???
Too windy to fly. (0 min 14 sec)

I took this around 1:30pm today. As you can see I didn't get my maiden done!
WX never cooperates when you want it to.

Dave,
You may be right about the more powerful motor but I know what times I get with the 500mAh batt on the BW so I figured it'd be a good choice for the maiden. That is if the wind ever decides to ease off a bit.

Mabuhay Guys,
Steve.
Jul 12, 2009, 09:03 AM
flyin' fool
goldguy's Avatar
Time to get out the Simple Delta.....................
Jul 12, 2009, 09:05 AM
D'oh.. Dumb Left Thumb
dekan's Avatar
Just what I was thinking


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