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Old Sep 13, 2010, 09:11 PM
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Freddie B's Avatar
Omaha Nebraska
Joined Feb 2006
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Originally Posted by doughpat View Post
More questions (now I see why this thread is 1000+ pages long...):!
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Which way should the motor turn? (need to know before I make the motor control wires semi-inaccessible)
Counter-clockwise as you face the plane fronm the front.

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I reinforced the LE and TE with a balsa dowel. Should I sand the edge into an angle, or leave it round?
Round leading edges have less drag, your decision based upon what it looks like.

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Hoping for maiden flight tomorrow
Good luck and have fun!

Fred
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Old Sep 13, 2010, 09:17 PM
Jack
USA, ME, Ellsworth
Joined May 2008
17,219 Posts
Quote:
Originally Posted by doughpat View Post
Wonderful video....thank you Wilfor. But just out of curiousity, what would happen if you only taped one side of the hinge with a full length piece of tape? Potential sloppiness? Maybe it will come loose?

Tips on whether to put the control rods on a certain side of the elevator/rudder? I'm thinking I'll put the elevator control rod/horn on the top of the elevator, so that it's protected from the ground, but the rudder one....hmm....
When you do that the hinge will work OK when it is pulled down towards the side without the tape but will tend to lift the tape in the other direction. So a better way is to make a hinge that will tape on the top of the hstab then go down through the slot and and tape to the bottom of the elevator and put two of those side by side in opposing directions to make two parallel tape hinges that cross in an "X" when viewed from the side.

Got you confused enough yet? See if this helps.

View the tape as === for the non-sticky side and xxx for the sticky side. Make two strips that look like this (the periods do not count, they are just holding the spacing):

=====
xxxxxxx
......xxxxxxx
......======

That is two short pieces of tape with the sticky sides overlapped a little and stuck together so one sticky side is up and the other is down. The overlap should be a little bit more than the thickness of the material so that it creates an area (in the hinge gap) where there is no adhesive.

Make eight of those for four hinges and put two side by side at each hinge point. Reverse one of the two pieces of tape so that the two cross over in the hinge gap when the sticky side in on the control surface or hstab.

Seen from the side the two side by side pieces of tape (the dashes) will form an "X" where they cross over and that will control lifting as the horn is pushed and pulled.

----\.../----
.......\/......
......./\.....
----/...\----

Are you going to cover your plane with clear or colored package sealing tape? If so, that tape will also make a nice hinge as seen in the attached figure.

Jack
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Old Sep 14, 2010, 12:00 AM
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Canada, MB, Oakbank
Joined Dec 2004
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Got a bad question to ask. What is the opinion of a 42" BBY in the range of 18 - 20 oz. The fuse and wings are built using only Gorilla Glue, so weight there is standard, for a KF3 wing anyways. But the reason for the extra is that I will be using older full size gear for the electronics. This will be staying at the cottage in summer so I do not have to worry about transporting my little guy back and forth, damaging it, or even have something happen to my radio. Does this still sound do-able to make fly? Motor will be a GWS geared 400, or direct drive 400. Weight estimated is everything but battery. But I will probably keep it at the 18 oz. level.

Also, another quick question. My KFM3 wing is still flat without dihereal, and Ailerons still not cut out. Would it be alright to put an inch of dihereal per side and fly the KFM3 with R.E.T. Thank you.
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Old Sep 14, 2010, 12:32 AM
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Freddie B's Avatar
Omaha Nebraska
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Originally Posted by NEW222 View Post
Got a bad question to ask. What is the opinion of a 42" BBY in the range of 18 - 20 oz. The fuse and wings are built using only Gorilla Glue, so weight there is standard, for a KF3 wing anyways. But the reason for the extra is that I will be using older full size gear for the electronics. This will be staying at the cottage in summer so I do not have to worry about transporting my little guy back and forth, damaging it, or even have something happen to my radio. Does this still sound do-able to make fly? Motor will be a GWS geared 400, or direct drive 400. Weight estimated is everything but battery. But I will probably keep it at the 18 oz. level.

Also, another quick question. My KFM3 wing is still flat without dihereal, and Ailerons still not cut out. Would it be alright to put an inch of dihereal per side and fly the KFM3 with R.E.T. Thank you.
Sounds do-able, but lighter flys slower. There is enough wing area though.

Shouldn't ask me about KFm3 and ailerons right now! Had my fill of that not working out right. Put 2" of dihedral in the 42" wing, don't cut out for ailerons. It will fly better R/E/T, really will!

Go back a few pages and see my flight reports on ailerons with a KFm3. Not good.

Fred
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Old Sep 14, 2010, 01:36 AM
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Canada, BC, Williams Lake
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Freddie my Kfm3 flys great with Ailerons , except i have 0 dihedral in my wing . Makes it a blast to fly
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Old Sep 14, 2010, 01:56 PM
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Freddie B's Avatar
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Freddie my Kfm3 flys great with Ailerons , except i have 0 dihedral in my wing . Makes it a blast to fly
Thanks for that. I did some searching on the advanced theory/science thread, and I am not alone with the situation I had manifest it'self. Some builds had dihedral, effecive ailerons, some no dihedral non-effective ailerons, and vice versa.

When viewing the wing from the front, even with aileron differential, the tops of the ailerons are blanked by the first step. It seems that the second step may just be too close to the hing line. I also have a very low aerodynamic CG, as I sunk everything low to help with stability.

If my plane is too stable, affecting everything else, it is what it is. KFm2 almost done, modified to 50% step at center of wing, 40% at the tips. Also trying a new wingtip design. If this cures things I will have some test data to go off of. If the problem exists, then it is for sure the airframe contributing.

KFm works, as proven by hundreds, if not thousands of builds. KFm3 will be tried on a mid and low wing plane soon in my 'factory' to see the diferance there too.

Fred
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Old Sep 14, 2010, 02:27 PM
Slipping the Surly Bonds
dz1sfb's Avatar
Attica, MI
Joined Dec 2006
10,750 Posts
Fred,
I was a bit disdainful of the KFm wing at first because of my experience on the Blue Baby. Having suspected the airframe geometry as the culprit, I built a test bed model. Based on the BB24, but as a shoulder wing and stretching out the vertical stab moment, I found to to fly more like a gasser model. This was a Kfm2 setup. In fact that model is pictured in this thread as the BB Sport 24. With that sucess under the belt I then proceeded to develop this line of combat design with lowcost components and nice looking models.
http://www.rcgroups.com/forums/showthread.php?t=1012551

The Kfm wing is a good wing. The UC wing is a good wing. Neither is a do-all for everything design though.

Ken
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Old Sep 14, 2010, 03:52 PM
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Freddie B's Avatar
Omaha Nebraska
Joined Feb 2006
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Thanks for that, and I'm going forward too on some KFm airfoil designs.

Cool link, by the way.

Fred
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Old Sep 14, 2010, 04:15 PM
Jack
USA, ME, Ellsworth
Joined May 2008
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Fred,

I've looked for it and can't find it but there was a point in time where a build that had the aileron hinge line about 3/8" from the step did not fly well. So it was decided that it was a bad thing to put the hinge line too close to the step. Shortly after, someone posted a photo of a plane that flew fine with a KFm wing that had the ailerons mounted directly to the step.

So at that point it was decided by the first decision was invalid. And that something else was either making the first build not work or the second build work.

I know you feel strongly that putting ailerons on a KFm3 is a bad thing to do but everyone else that has done it with varying degrees of success does not agree. I still think there is something else at work here between your build and your expectations for the results. I also think that it is not a good thing to condemn it out of hand for everyone and say that it is characteristic of the build.

Just friendly discussion, we can agree to disagree. But I think ailerons on a KFm3 wing are a good thing, especially of the wing has little or no dihedral.

Jack
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Old Sep 14, 2010, 06:46 PM
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Freddie B's Avatar
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Originally Posted by jackerbes View Post
Fred,

I've looked for it and can't find it but there was a point in time where a build that had the aileron hinge line about 3/8" from the step did not fly well...... that something else was either making the first build not work or the second build work.

I know you feel strongly that putting ailerons on a KFm3 is a bad thing to do but everyone else that has done it with varying degrees of success does not agree. I still think there is something else at work here between your build and your expectations for the results. I also think that it is not a good thing to condemn it out of hand for everyone and say that it is characteristic of the build.

............ But I think ailerons on a KFm3 wing are a good thing, especially of the wing has little or no dihedral.

Jack
Jack!

Let's back up, and I hope that my discussion did not insite a mis-conception of what I tried to say.

I'm liking KFm airfoils. I think what I've said is 'MY KFm3 wing, put on MY Blue Baby, was a complete failure ONLY ON THE AILERON issue. Plane flys great, lands well, even performs well if I coordinate some rudder.

I think I've stated that I do believe it is the, or should I say, MY BLUE BABY. We are short coupled, large stab, huge lateral area, and a top wing, plus let's go ahead and blame dihedral! Could be CG issue too, but the plane flys great power on, power off, full throttle, mid and low throtthle (so I ruled that out).

Most interesting thing was how I can get almost no roll action out of the ailerons. (barely blip rudder, wala).

You stated some have success, some not, and that is what I would like to eventually find out. I don't like building the same thing twice, but I am not giving up! I just build slower than some.

So I'm unable to remove some step on wing #1, too much glue. I could add material up to the hinge, but I'm thinking that is not what I want to do. I could add panels to remove the step, flairing it into the ailerons, not going to happen!

I will always wonder: Since I took Tony's plan, built the BB, used his plan to make the KFm3 wing, ailerons and steps where they are shown on Tony's plan, possibly thousands have been built, and mine has terrible aileron issues? (I'm not alone, more success than failures I presume). Oh by the way, if you study Tony's plans, all sizes, he adds dihedral in his design, just less with KFm. AND Tony was a big proponet of KFm, so pardon if I ponder what the heck is going on.

Anyway, let it rest, until I can post some more facts and test results as it relates to MY PERSONAL EXPERIANCES with the BB and KFm3. I am.

I did discover that several people I find to be reliable (and I would include you in that group), have huge success with KFm3, ailerons, and these seem to be mid-wing, low wing, flying wings, gliders, etc. The only place I've heard anything bad, is on short coupled, high wing, aircraft, like the BB. But again, some have no issues at all????????????????????

Also I'm trying the obvious next. Step not so far back, or at least not so close to the aileron hinge line. Simple enough to figure the step/vortex effect is blanking airflow at the up moving aileron. If I had air hitting that big old aileron, it would do something more than it is. The bottom one is working, and is deflecting air, or it wouldn't cause such large amounts of reverse yaw on me. Along with that if the upper aileron was in the airsteam, it would counter act the yaw issue, since it is moving up twice what the lower one is.

So many words, I could be building! Bottom line, My WING is defective, hope I figure out why so I can report back to you all.

Fred
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Last edited by Freddie B; Sep 14, 2010 at 06:53 PM.
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Old Sep 14, 2010, 10:18 PM
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Canada, MB, Oakbank
Joined Dec 2004
690 Posts
Thanks Freddie. That was exactly my thought. Will be doing that instead.
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Old Sep 14, 2010, 11:39 PM
Crash it first, Then fly it
Griffindor's Avatar
The Big Apple
Joined Jul 2008
536 Posts
Quote:
Originally Posted by jackerbes View Post
When you do that the hinge will work OK when it is pulled down towards the side without the tape but will tend to lift the tape in the other direction. So a better way is to make a hinge that will tape on the top of the hstab then go down through the slot and and tape to the bottom of the elevator and put two of those side by side in opposing directions to make two parallel tape hinges that cross in an "X" when viewed from the side.

Got you confused enough yet? See if this helps.

View the tape as === for the non-sticky side and xxx for the sticky side. Make two strips that look like this (the periods do not count, they are just holding the spacing):

=====
xxxxxxx
......xxxxxxx
......======

That is two short pieces of tape with the sticky sides overlapped a little and stuck together so one sticky side is up and the other is down. The overlap should be a little bit more than the thickness of the material so that it creates an area (in the hinge gap) where there is no adhesive.

Make eight of those for four hinges and put two side by side at each hinge point. Reverse one of the two pieces of tape so that the two cross over in the hinge gap when the sticky side in on the control surface or hstab.

Seen from the side the two side by side pieces of tape (the dashes) will form an "X" where they cross over and that will control lifting as the horn is pushed and pulled.

----\.../----
.......\/......
......./\.....
----/...\----

Are you going to cover your plane with clear or colored package sealing tape? If so, that tape will also make a nice hinge as seen in the attached figure.

Jack

that's what I do. I eith cut the bevel, or sand it, which is so much easier and nicer looking. Sanding is also better for a rudder.

My dad will let me buy the readifoam, and I'm going to make a UC wing for my 42" with an RET setup!!!

Can't wait!!!
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Old Sep 15, 2010, 10:52 AM
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Joined May 2009
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Anyone ever just omit the landing gear entirely and do Pete Rose (i.e. belly) landings in 3" tall grass?

I just got really frustrated trying to find an allen key small enough to tighten my wheel collars, so I got to thinking: My flying field is grassy anyway....why the heck am I even putting wheels on this thing?

Maybe I should put some Blenderm tape on the bottom fuse to protect it, if I do go for the bare-bottomed approach. Seems like the plane would fly better w/o gear anyway...no?

Hoping to maiden tomorrow, if the Bangkok afternoon wind will stay down!
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Old Sep 15, 2010, 10:53 AM
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LaGrange, GA
Joined Jun 2009
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Awesome Griffindor! I've got a UC BB42 made out of Readiboard with one of these motors on it http://hobbyking.com/hobbyking/store...idProduct=5354 and it flies like a dream! Good luck with your project!
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Old Sep 15, 2010, 11:16 AM
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Wilfor's Avatar
Canada, BC, Williams Lake
Joined Jan 2010
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Quote:
Originally Posted by doughpat View Post
Anyone ever just omit the landing gear entirely and do Pete Rose (i.e. belly) landings in 3" tall grass?

I just got really frustrated trying to find an allen key small enough to tighten my wheel collars, so I got to thinking: My flying field is grassy anyway....why the heck am I even putting wheels on this thing?

Maybe I should put some Blenderm tape on the bottom fuse to protect it, if I do go for the bare-bottomed approach. Seems like the plane would fly better w/o gear anyway...no?

Hoping to maiden tomorrow, if the Bangkok afternoon wind will stay down!
I Fly both mine with wheels as i land in grass most of the time that would eat the wheels. Make sure you put something on the bottom to protect it though blenderm would work fine or just some clear packing tape .
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