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This thread is privately moderated by jackerbes, who may elect to delete unwanted replies.
May 17, 2010, 06:33 AM
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Quote:
Originally Posted by jackerbes
At how many volts? You can crunch the numbers a little here:

http://www.rcpro.org/rccalc/PitchSpeed.aspx

With a 6" pitch it would take more than 25,000 RPM, with a 10" pitch more than 15,000 RPM. I'm not sure that either would be practical because of propeller RPM limitations.

Jack
4S 1800mAh 40C lipos. I've seen a scratchbuilt wing do 144mph on turnigy 2836 3700kv with 4.1x4.1 prop on 4S, so that sounds like a great setup
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May 17, 2010, 07:19 AM
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davereap's Avatar
Use high kv ..high powered motors...at high volts.. with a small prop..
I can never believe how small a prop can get some of those racers going so fast...
Have a chat with the people from overlander batteries here in the UK.. they often fly an electric high speed racer in a demo at shows here...its so fast its not credible..looks faster than almost everything except those glow powered racers..and by fast I mean B***** fast...I dont know how its wings take the strain when it banks round..

re the Dart.. its all done bar one pushrod, My KFm4 build as usual comes in heavier at 16oz AUW with a 3 cell 1250 and my overpowering but heavy motor combo that will give 26oz thrust..its an extended 32" span with 3sqft ...The usual build method has produced a nice strong stiff wing...
Last edited by davereap; May 17, 2010 at 07:31 AM.
May 17, 2010, 10:53 PM
Onward through the fog.
Cybernaught's Avatar
Good luck with the Dart, Dave. When do you think you will maiden?

Got some vid uploaded here in Tagbilaran at the Cybercafe.

1.
Slinger Maiden.
This is a podless version of the Featherwing 40 Finless Flying Wing.
Singer maiden.mp4 (3 min 50 sec)


2.
Slinger Session 2
There are some out-takes at the end of this one.
Slinger S2.wmv (4 min 8 sec)


3.
Miss Piggy Maiden.
This is the tapered wing version of the Featherwing podded Finless Flying Wing. Vent holes in the front make it look like a pig's snout head on view.
MP Flies2.wmv (2 min 39 sec)


A couple of pics below too.
I have 4 finless planes and the Featherwing 40 still needs final balancing and a maiden.
Maybe tomorrow!


Steve
May 18, 2010, 07:27 AM
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davereap's Avatar
Yours are all going well...they certainly roll better than my new one

The Dart is maidened and the videos are being processed by youtube right now, so I will post them here asap..
So how did it go.. No problems, the flight was totally fine, its just a matter now of adjusting the COG to its sweet spot, and making the rudder have more effect..
Before I flew I knew I had not enough movement, the hinge tape was too loose and I was dubious.. but it had to fly, and fly it did
So the result is pleasing, the wind here is up as usual and going through the blocks makes loads of eddies and turbulent air, it can be heard on the videos. The dart is a well established design and my heavy KFm4 version goes smoothly, so no complaints, it just needs a much more powerful rudder to suit me..and thats in process now, so more videos tomorrow if the weather holds up

video up ..that was fast
dart-maiden1.AVI (5 min 13 sec)

.
Maiden2 dart xs KFm4.AVI (4 min 20 sec)


edit
next modded with a much bigger rudder, the rolls are better but still poor.
Any more ideas welcomed... I am thinking to cut the total fin rudder size down considerably, because of the kiting previously noticed..then I will have a bigger percentage fin to rudder..say 30-60..and try again..Its so stable its possibly too stable
heres the video
Maiden2 dart xs KFm4.AVI (4 min 20 sec)
Last edited by davereap; May 18, 2010 at 02:03 PM.
May 19, 2010, 09:24 AM
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davereap's Avatar
I chopped the fin again, which gave a slight improvement, the rolls are still poor but the plane is a lot of fun...All I can think is the KFm4 on this is just making it too stable. Ive got a massive rudder here and I can chuck it about like mad, but the roll is slow and out of shape.

.
ruddermod2.wmv (7 min 4 sec)
May 19, 2010, 09:38 AM
fix-it-up chappie
tolladay's Avatar
Quote:
Originally Posted by davereap
I chopped the fin again, which gave a slight improvement, the rolls are still poor but the plane is a lot of fun...All I can think is the KFm4 on this is just making it too stable. Ive got a massive rudder here and I can chuck it about like mad, but the roll is slow and out of shape.

.http://www.youtube.com/watch?v=_MeKsfn2i6s
With a wing that fat (that much surface area), and with the dihedral, no amount of fin is going to give you smooth rolls. I suspect if you made it a flat wing, or almost flat, and tried ailerons, you'd get a better roll rate, but it wouldn't be as gentle a flyer.
May 19, 2010, 10:00 AM
Registered User
Quote:
Originally Posted by davereap
I chopped the fin again, which gave a slight improvement, the rolls are still poor but the plane is a lot of fun... I can chuck it about like mad, but the roll is slow and out of shape.
If you'd like a faster roll rate with less yaw, I'd suggest increasing the dihedral. A quick way to experiment would be to add up-swept wing tips. It's possible to do "axial" rolls with rudder-elevator, but you need a lot of dihedral, and some "down" elevator input when the plane goes inverted.
May 19, 2010, 10:03 AM
gpw
gpw
“There’s no place like Foam”
gpw's Avatar
Perhaps be happy with the classic "barrel roll".. Which the Dart should do easily..
Latest blog entry: Lost plans
May 19, 2010, 11:02 AM
Registered User

improving roll rate?


Dave: great videos, great performance. even if that's all that the plane can do, it's terrific, and i would like to try 1 and see. where can we get details?
i see opinions to improve roll rate: 'increase dihedral'; 'decrease dihedral'.
for all that i know, aerobatic planes have no dihedral, and do rolls with aileron-maybe assisted with rudder-but is hard to roll with rudder only, so i think the plane is fine the way it is, as a stable, slow flying thing.
besides that, as you suspect, side area plays an important role, and how much and where you place it influences the performance. for instance, if too much beyond the center of pressure (like a large fin/rudder), it will behave as a weather vane: easy facing the wind, but when turning, will always want to face the wind again. and if high or low, also.
there was an empirical way to calculate it, in 1 of the books by Frank Zaic, by making a cardboard template. i'll try to rescue my books and see if i can find it. or somebody there has it?
and, if the plane is too stable, another thing that may help is making the step smaller-lower. ????
Last edited by phil alvirez; May 19, 2010 at 12:54 PM.
May 19, 2010, 08:46 PM
Onward through the fog.
Cybernaught's Avatar
I'm working on a KFm2 Featherwing-40 Finless Canard.

I won't cross post and it really belongs on the canard thread so you can see info and pictures here if interested.

https://www.rcgroups.com/forums/show...2#post15126897

Steve.
May 20, 2010, 03:13 AM
Registered User
davereap's Avatar
The Dart thread is here..with plans
https://www.rcgroups.com/forums/show...hlight=dart+xs

My version was slightly lengthened in the chord to 24", built at 32" span and given a KFm4 wing..the fuz is 3 layers of 6mm depron fitted to the wing, with a tube mount let into the front.. at the front Ive added a couple of extra layers on the fuz to strengthen where the mount is fitted..
My wing build always uses the same method, its only varying the wing shape, so a check on my builds will find some illustrations

I know I am moaning about the roll, but in reality its an excellent fun flier... I will say I am enjoying it as much as my Nutball, and in a lot of ways it flies much the same when you make it in the larger sizes, it just comes in at a higher wing loading because of the smaller wing area/span...and thus it flies that much faster...But all in all I highly recommended it..
here are the lines for the dart... some sizes need rounding off..
Last edited by davereap; May 20, 2010 at 03:50 AM.
May 20, 2010, 03:27 AM
Boooriiiiing.
MadMonkey572's Avatar
I'm thinking about building a Superfly-style combat delta out of flat foam... I'm wondering if a KF2 or KF4 would be better since I'm going for maneuverability (or no KF at all??).

Motor would be a Suppo 2212/6 with 6X4, 30a with elevons/throttle only.

Suggestions? Depending on the reply I get I may throw one together tomorrow. Also, is it absolutely necessary for the KF to extend the full 50% of the wing chord? This would be a delta after all and it's pretty much a giant wing.
May 20, 2010, 03:52 AM
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davereap's Avatar
superfly clone here
https://www.rcgroups.com/forums/showthread.php?t=977954
might be of interest... KFm4 build and it goes very well
May 20, 2010, 04:37 AM
Boooriiiiing.
MadMonkey572's Avatar
Perfect! Do you think it would work alright with just a KFm2 or is that bottom foil absolutely necessary?

Thanks for the link, I'm going to work off of that design.
May 20, 2010, 07:02 AM
Registered User
davereap's Avatar
KFm2 will be fine but I think the KFm4 has the edge for aerobatics, its more like a symetrical section.
KFm4 also makes for a stronger stiffer build than KFm2 when you use the method in that link..
More layers give more strength..important if you are doing combat
It also depends on what foam you are using... if depron, then 3 layers KFm4 with tape over will be far stronger for combat..
If 1/2" white foam like steve has to use,, then KFm2 makes a better build..

either way multi layers of foam are better than a single layer for strength.. and sticky tape cover makes the whole thing vastly stronger..

So what foam?


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