A simple build Plank with KFm4 section.. with WOW! factor.. Called it the "Nifty" - Page 2 - RC Groups
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Jul 09, 2009, 02:48 PM
Use whatcha got!
msmith's Avatar
Making strips from a plank is a great way to save money... You can go with the yardstick and a knife, or get one of these: http://www3.towerhobbies.com/cgi-bin...?&I=LXAA63&P=7

Surprisingly enough, my LHS actually had one of these in stock recently... Will have to see if its still there.

-ms
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Jul 09, 2009, 04:24 PM
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davereap's Avatar
balsa stripper..thats the same one exactly I bought years and years ago, and it goes up to just about that 3/4" width..seriously a must have tool.. and it is a cost effective way to make strips at any size... that and a david's balsa plane and a permagrit wedge shape sanding block..etc etc..

Ive just posted a video back on page 1 post 15..

With the 18% COG position I had it trimmed for a steady run at about half power, so when more power is added the model climbs and will eventually loop. even so the plank will loop or change direction fast and tight.
What it wont do is high alpha slow.
On its second flight today I moved the COG to 20%.this is nearly as far as it will go..retrimming for a half power cruise made the powerup give less of a climb, and inverted need only a touch of push.. But oh boy does it come round fast, if banked and yanked it reverses direction so quickly you almost miss it..The rest of its flight is still stable and easily controlled..so the next test flights will be at 20% with more slow and high alpha.. then I can try just a bit further back.. I would like to get slow high alpha, but we will have to see if is is capable and stable..
As my other half said in the video...." pretty nifty init " ..do you need that translated ? ...hence it is now named the "Nifty"
Last edited by davereap; Jul 13, 2009 at 05:22 AM.
Jul 09, 2009, 09:55 PM
Registered User
bullseye000's Avatar
Dave did you put any reflex in the elevons like the robot birds plane pictured above? This looks like it would be a fun flier.
Jul 09, 2009, 11:50 PM
Registered User
All i can say is COOL. I really really like the design. More videos
Jul 10, 2009, 02:23 AM
Registered User
davereap's Avatar
This really is a simple fun flier... named it now as the "Nifty" ..thats what my other half called it..

The recomended starting point for the COG on the KFm4-plank is at 18% and it has 3-5mm reflex up set on the elevons. ( launch and trim at just over half power )...Note this is a safe starting point, not the best COG which is further back..
when you get back to 20% there is still a touch of up needed and you need to go easier on the elevator untill you get used to it, it now responds almost as quick to the elevator as it has always done to the ailerons, movements are 35mm each way for any individual control... more when mixed.... Do have lower settings if you want a less responsive flier... I use 70% expo so I can have a gentler flight but still have all the movement when required.
It is still stable at 20% and inverted needs a slight push to keep it level.. so I think the COG can go back some more, do take it slowly though wont you...

The robot birds plane has a forward COG 12% and what looks to be a fair old bit of reflex. Its a nice flying model says the reviews, and bounce proof because of the foam it uses.. also looks nice with the decor.. a good'n

edit....I just had a longer fly all at 20%.. rather too windy today , the plank will fly slow enough to travel backwards.. it tends to wobble a bit at these slowest speeds holding high alpha, ( would tips fins extending lower help here ?) but it is always controlable... At normal speeds it handles the wind nicely, always smooth.
20% loops can be made very small.. back flips are possible.. there is definately a bit more rearward cog movement to get, inverted is still needing a push to keep flat.
Last edited by davereap; Jul 13, 2009 at 05:34 AM.
Jul 10, 2009, 07:01 AM
Jack
jackerbes's Avatar
We need to get another one of these in the air. I think it is a good candidate for me for a front yard sized flier so I cut one out of FFF yesterday. That worked out great, I got all the parts (all three pieces) out of pieces in the "big FFF scrap" pile. It's cool when you can start a build without having to cut a new sheet of FFF.

I'm not trying to to build quick, I wonder how long it will take to get another maiden report on the The Plank.

Jack
Jul 10, 2009, 08:11 AM
gpw
gpw
“There’s no place like Foam”
gpw's Avatar
Why not use Foam spars ???? LIGHT... Probably waaaay stronger than we'd need ... Perhaps a skewer embedded in the center for the overly concerned ... that's where all the stress is....
Our B2 is merely two pieces of FFF glued together (PB3 wing and KF strip, no other reinforcement) ...flown Many times , no troubles... Plank done like this would be a Feather...
For easier balancing with lighter gear , you could always extend the nose a bit ???
Jul 10, 2009, 09:28 AM
Registered User
davereap's Avatar
It depends on how you fly, but ive had wings fold before, and I am sure even if you really try hard ...you wont break this one..

leave out the balsa spars and you might be sorry.. The stresses on the wing when you give it full elevator must be high, cause it comes about in a flash, and I do mean a flash.. and you have about 6oz of battery and motor wanting to carry on in the original direction..

It is however a good idea to try some lighter builds..or some different sizes..depending on what foam bits you have arround... mine is great for here, where we are always getting 8-10mph winds..Fly it jet like and its well smooth, or just cruise it arround
What I would also like to try is a higher kv hot motor..I think this wing will take a lot more power through it.. but perhaps it might be wise to strengthen the elevons if anyone goes that route..

yes please... get another going for a second opinion...its a shame we are all so spread out, the original concept is for a streamer towing combat wing.. now that would be fun, but I doubt my reflexes are up to that..
Last edited by davereap; Jul 10, 2009 at 09:34 AM.
Jul 10, 2009, 09:42 AM
Use whatcha got!
msmith's Avatar
Quote:
Originally Posted by davereap
...the original concept is for a streamer towing combat wing...
Now thats something that I could get into...

I'm a sucker for combat...


Besides the typical dart combat (standard dart, round dart, tandem dart, martian dart, etc.) that we've done in the past, we've actually flown combat with epp Skyrays (gpw literally cut my motor off of my F4D and its a pusher!), we've flown combat with his Big Simple Fokker biplane and my eStarter (no kidding), and we even tried combat with Trainer 1's, but they were so slow and 'Trainer Like' (imagine that), that we couldn't even get close to each other, but we did laugh a lot...

If/when I get time to build this one, I may deviate from my normal 'change everything into a profile fuse' mentality and build the box fuse per the plans b/c I found a hot wind CCDR on the bookshelf last night that is already setup for a firewall mount.
Jul 10, 2009, 01:54 PM
jclassic1
I have noticed in the vidio,s that this wing seems to fly a bit fast for a new flyer with only a handfull of nutball flights to go by.Will this one be too quick for a novice flyer.


John
Jul 10, 2009, 04:30 PM
RIP Azarr - "Old age is not for sissies"
Azarr's Avatar
Quote:
Originally Posted by jclassic1
I have noticed in the vidio,s that this wing seems to fly a bit fast for a new flyer with only a handfull of nutball flights to go by.Will this one be too quick for a novice flyer.


John
I would guess it depends on your nutball. From the video it seems very stable in flight and appears to slow down pretty well. I would think maybe some smaller elevons or very little throw and some expo and it would be fine. It certainly won't self right like the nutball does with all that dihedral. (I do love that plane)

Funny, I was thinking it seemed slow and needed a higher Kv motor

This looks like a good build for our combat program. Unfortunately we're required to use the TP 2408-21. If the weather is bad this weekend I'll probably build an 90% version (720mm = 28.35") I'm thinking 3/16 sq for the spars, 6mm with 3mm KF steps. That should bring the weight down some and work well with the motor we have to use.

Azarr
Jul 10, 2009, 05:55 PM
Registered User
davereap's Avatar
The nutball is one of the best fun designs Ive found, I think suitable for beginers and great fun for more advanced fliers...I always plug the big ones, and have more than a few now..A 36" KFm4 is my latest build and I love it..
This plank will fly steady ..check the circuits in the middle part of the video.. but it will not self right itself like the nutball does, and it does not have the fantastic slow speed harier like stability.
The plank will stay in the attitude you put it, which means you have to fly it all the time, but it does not give you any problems because its so smooth in what it does..

To fly this you need to be ok with flying ailerons and elevator, and past the need to have the stability that a nutball gives you..

Dont make the elevons smaller... decrease the throw and have lots of expo.. for steadier flying only fly at 3/4 power it will cruise nicely like that..

Speed... you are correct ..as i said in post 23 a higher kv might be a way to get some serious speed out of the thing..Its speed at the moment suits me, I have a preference for slow and low, hence the love of nutballs, This as it is, gives me enough performance. It has good vertical and I can keep up with it. It also is more suited for the flying site I use.. Not too fast to be a cause for concern from other users on the field..
Jul 11, 2009, 12:19 AM
jclassic1
When flyers mention use plenty of expo to fly certain models how do you manage without a computor radio.I have a Futaba Skysport 6a which has no programming options.This does tend to stop me building some of the models I would like to try.

John
Jul 11, 2009, 04:20 AM
Registered User
davereap's Avatar
John Thats a problem... you can only use dual rates and fly with less movement untill you get used to it... or you can have longer sticks on the tranny..some have screw out ends for length...
I must admit I flew with the standard sets for more than a few years.. but the computer sets make everything easier. and now, well I wouldnt use anything else.
Expo lets you make larger stick movements for less control surface movements when near the centre stick position and this just smooths out heavy thumbs. Or shaky old nerves..And thats just one benefit of a computer radio.
If you can afford one you wont regret the outlay...the new tx 6's on 35Mhz are about £85...
I just treated myself to a ff10 TX the module type, unfortunately only on 2.4G, So I took out their 2.4module because the futaba REC's are too expensive..and replaced it with a 35 module from my ff9c... I replaced that module with a corona 2.4G set and then bought 4 of their REC's for the cost of just one futaba REC.. The corona stuff is working well..
All that gear should see me out...

Azarr Ive got one of those 2408-21 motors so I will try it and see how well it suits... from reviews it would seem the motor will give less thrust, but on a smaller prop it might give it better speed..its an easy experiment to try.
The 32" plank will fly on reduced power with no problems, but as you said a smaller version will suit your specified motor better
Last edited by davereap; May 06, 2010 at 06:47 AM.
Jul 11, 2009, 05:06 AM
RIP Azarr - "Old age is not for sissies"
Azarr's Avatar
Quote:
Originally Posted by davereap
[

Azarr Ive got one of those 2408-21 motors so I will try it and see how well it suits... from reviews it would seem the motor will give less thrust, but on a smaller prop it might give it better speed..its an easy experiment to try.
The 32" plank will fly on reduced power with no problems, but as you said a smaller version might suit your specified motor better
Plus we're dragging a 20" streamer. For combat I've tried wings up to around 32" and with the equipment we're using something in the 26-28" range seems to come out right in both wing area and weight. (still looking for the holy grail combat plane, quick and cheap to build with great performance) We're supposed to have rain off and on all day today so I should be able to get to it. I'll post pictures if I can.

FWIW, we're abusing the heck out of that motor. We're running them at around 160 - 180W and I've been surprised at how well they've held up.

Azarr


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