Amokka Race Plank - Page 4 - RC Groups
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Oct 30, 2008, 01:41 PM
Registered User
Marc10's Avatar
Quote:
Originally Posted by Peter Wick
...it would probably very interessting to give an Amokka to a more experienced F3F pilot to hear his opinion. This will for sure boost the development of F3F planks.
That would be very interesting... some people in Spain think that it is not competitive because the lap time in the video was 5-7 seconds.
http://www.miliamperios.com/foro/viewtopic.php?t=114241

Maybe the discussion is too focused on breaking....I assume the first objective is F3F performance, isn't it? (well, I really love the wing too)
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Oct 30, 2008, 02:24 PM
Registered User
Actually I just was very happy with the plane and it`s performance. I was just enjoying it.

How big the gap is between the Amokka and some real (!!!!) F3F planes is, I do not know. But as far as I know and as I see it is the Amokka one of the only serious, means moulded approach, to design a high performance plank. There is still a long way to go, but designing good planks is maybe also 20 years after designing good F3F models. I am actually very sceptical about if it will be possible to come at least close to the performance of an conventional F3f plane.

But on the other hand, I take it as a compliment, that some people trying to jugde the Amokka`s F3F performance, so at least they seem to think about comparing it.

And I am eager to try it. And maybe I will give one Amokka to an experienced F3F pilot.

So far I just wanted to share my pleasure and ruine some prejudices about flying wings.

@shedofdread: If the break from 31 is mounted above the wing it will still affect the pitching moment of a plank.
Oct 30, 2008, 04:40 PM
Deniable plausibility
Shedofdread's Avatar
Peter,

To get around the trim change issue with airbrake deployment, I'll line the centroid of the 'brake with what I estimate the centre of drag to be. In reallity I suppose this will be level with the wing.

I was going to use a modified (cut down) F3x style fuz but to make the brake neat and large enough, I'll have to mould a new, dedicated plank fuz.

Even if F3f planks don't have the performance of their tailled brethren, they do have the advantage of portability. One of my goals is to have a high performance slope model that will go in the boot of my car.

S
Oct 30, 2008, 05:52 PM
Twisted and Confused
flyonline's Avatar
Quote:
Originally Posted by ENGINETORQUE
Not sure If we exchanged PM's - anyway it's dead simple - long extension on the servo arm - servo on it's side and a similar length link to the canopy

Cheers
Ahh, now I understand. I had thought that there was a 3rd link between the servo arm and the pushrod (sort of bellcrank like), but I see that I was wrong .
Oct 30, 2008, 06:13 PM
Registered User
ENGINETORQUE's Avatar
Quote:
Originally Posted by flyonline
Ahh, now I understand. I had thought that there was a 3rd link between the servo arm and the pushrod (sort of bellcrank like), but I see that I was wrong .

I expected problems - thought the canopy would blow back or even open during flight but due to the shape of the Jart it blows shut, so that's good! The brake itself will hold open if you open it at speed, but that's not how to use it, so I only did it to check - servo is just a Futaba 148 - a stronger servo would overcome that but for landing approaches it's brilliantly effective.

Cheers
Oct 31, 2008, 07:42 AM
Registered User
Marc10's Avatar
Quote:
Originally Posted by Peter Wick
And I am eager to try it. And maybe I will give one Amokka to an experienced F3F pilot.
I would like to be an experienced F3F pilot...
Oct 31, 2008, 08:32 AM
Registered User
skirmish's Avatar
Peter. It's a fascinating project that you're involved with as I along with a few of my club colleagues have always had a view that a well designed and constructed plank should be capable of competing well in F3F. While dipping our toes into F3F we tend to be more involved with EPP60 racing and design our models for that class of competition but we are well aware of how fast a well designed and set up 60" model can fly and especially how well they can turn. It would be great to see a plank competing at the top level with the conventional type models. Good Luck with your progress.
Dave
Oct 31, 2008, 08:22 PM
C'mon more Energy
Swoopdown's Avatar
Good on you Peter. Always loved planks ever since my first one.
I have always dreamed of a molded plank. The best I have seen was the Manta but massive reflex in the centre of the wing its clear that its not built for speed.
Good luck and I hope that further testing and set up proves your Amokka to be a real wepon.
Nov 01, 2008, 06:46 AM
The Flying Kiwi
Quote:
Originally Posted by Peter Wick
well, problems are here to be solved.

The problem with the crow setting right now / if you can call it a problem / is more that because of the rather straight leading edge the inner flaps are quite far from CG, haveing a strong impact on the pitching moment. It is easy fx to fly the Amokka just with the innner flaps alone as elevator.
But during crow breaking this down pitching moment has to be compensated by the ailerons. Even the span of the inner flaps are much shorter than the ailerons, the Amokka loses too much lift by the uptrimmed ailerons. So drag is fine during crow breaking, but lift could be better.

Solutions: Another planform or making the inner flaps even shorter. I tend to the second solution.
Peter: I've found thru trial and error, that a 4 servo JW responds quite nicely to a 60/40 split of aileron to flap. It handles like a pussycat, and has about a 30% reduction in landing speed at a max of 30 degrees of flap. Any wider flap , say 50/50 and you have trouble slowing because of excessive pitching moment.

I've been wondering, if having 4 flaps side by side plus 2 ailerons would be a good option for your Amokka. That would allow 2 outer flaps to be diflected down 90 degrees, and 2 inner ones up 90degrees, creating a large amount of drag, with little pitching moment.

I bet it would take a bit of head scratching to figure out a transmitter programme to run it!
Nov 01, 2008, 11:41 AM
Registered User
Dear Ralph

tought about that too. Actually the split flap / aileron is 35% /65% on the Amokka. So we are rather close
The 6 servo idea has come to my mind too, but will complicate to hole system a lot, programming, search for the settings and so on. One thing I actually like about planks is the sheer simpicity. So I am still looking for some easier solutions. One thing i really want to spoil is having ailerons and elevator along the hole span, which in turn kills some otherwise good breaking ideas.
As said before, the discussion still seems to focus to much on that the Amokka is having a serious breaking problem. I don`t think so....it is just not as good as on others F3X planes.....on the other hand F3F is not a landing competition.....landing is more about not crashing.
Maybe the breaking could be more effektiv, if my inner flaps will deflect 90 degrees downward, which in turn will maybe not create a much bigger negative pitching moment as the 20 degrees I am using now. It could well be that at 20 degrees there is still some attached flow on the flap, creating a high amount of up pitch. If the airflow is completely separated, the pitching moment will probably not rise at lot more. I did had similar problems once on a conventional F3B ship, which could easily be solved by just dropping the inner flap a lot more, everything was much more predictable.

Yours Peter
Nov 02, 2008, 02:30 AM
Scorpian 60'' 2012
BMtech's Avatar
Peter: what about using a Gyro for pitch when the flaps are deployed, The gyro could be turned on with the gear switch & as the flaps are fed in the gyro would compensate the pitch change ? ,this is what Ill be trying when I get my 2mt plank finished.

Rick
Nov 02, 2008, 02:42 AM
auto-tune remix
slopemeno's Avatar
A gyro might be a slick idea.
Nov 02, 2008, 12:14 PM
One Idiot is plenty...
Dbox's Avatar
Quote:
Originally Posted by BMtech
Peter: what about using a Gyro for pitch when the flaps are deployed, The gyro could be turned on with the gear switch & as the flaps are fed in the gyro would compensate the pitch change ? ,this is what Ill be trying when I get my 2mt plank finished.

Rick
This is a great and simple idea,I am using gyro in hotliners in speed up to 200Mhp when windy.Stabilize low speed passes,plane goes paralel to the ground without pitching .Gyro slowes down controlls a little ,though.But would be good for landings.
Yuri.
Nov 03, 2008, 05:42 AM
Scorpian 60'' 2012
BMtech's Avatar
Gyro slowes down controlls a little ,though.But would be good for landings.
Yuri.

This could be good as well ,I think a gyro that could be adjusted in flight for set up would save a lot of time & may be some damage on the hot landings

Rick
Apr 20, 2014, 10:51 AM
Registered User

Amokka Race Plank


Hi All

Nearly 5 years ago Peter was kind enough to make an Amokka for me. Unfortunately it’s taken me far longer than I had hoped to finish the plane. Yesterday I flew my Amokka for the first time and I have to say I think it’s absolutely BRILLIANT.

I had thought about using a Linear Drive System but decided to use traditional pushrods with MKS 6100 servos on the flaps and MKS 6125 servos on the ailerons. I made the flaps 300mm long to try and get a good balance between the surface area of the flaps and ailerons for crow braking. For the first flights I used the C of G (48mm), the control movements that Peter suggested and set up a rotary dial on my transmitter so that I could change the trim of the whole trailing edge.

I am very impressed with the speed and energy retention of the Amokka. Even in light slope lift with the occasional thermal it was possible to fly multiple loops with a diameter of around 50 meters. I found the elevator to be very powerful and quite sensitive. After the first 4 hours of flying I have settled on using 35% exponential for the elevator and 20% for the ailerons. With these settings I found it was possible to fly tight F3F type turns without loosing too much speed. My initial impression is that reversal turns suit the Amokka better that knife-edge ‘bank and yank’ type turns.

After some trials I am now using more up aileron (20mm) and down flap (25mm) for crow. Although this doesn’t reduce the speed of the model it is very useful for loosing height on the landing approach.

For future flights I will try moving the C of G a little further back (but not too far ;-). I am also planning to set up a special mix to open the crow brakes on only one side or the other of the wing at a time. I will use these ‘drag brakes’ in place of a rudder for flying stall turns.

As well as finishing the Amokka I’ve also been following the development of the Snap and Spliff flying wings with great interest.

My sincere thanks to Peter for making an Amokka for me. It's a BRILLIANT glider and makes a nice change to the gliders that I usually fly. I am looking forward to getting to know it more and flying it on a regular basis.

Kind Regards

Keith
Bristol
Last edited by groom_k; Apr 20, 2014 at 10:56 AM.


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