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Old Sep 30, 2010, 11:00 AM
just Some Useless Geek
Chicagoland
Joined Oct 2008
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Quote:
Originally Posted by frednjess View Post
Here's my KF wing project page...
Hey! <still> Gotta keep 'em sep-a-rated.
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Old Sep 30, 2010, 11:39 PM
That Guy Who Flies Wings.
La Vista, Nebraska
Joined Mar 2007
395 Posts
Quote:
Originally Posted by Freddie B View Post
Cool project, simple and BIG! Don't take any of those Heli dudes at the La Vista field or they will ban you forever! Your video looked like the B-2 doing a flyby! LOL. Back to KFm discussions, sorry!

Fred
Well, I'm kind of in good with the heli crowd...Damn their rotor wing madness!
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Old Oct 01, 2010, 09:31 AM
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United States, DE, Bear
Joined Apr 2007
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The first test wing is ready for first flight. A pitot-static system is built into the leading edge for airspeed measurement. The wing airfoil is almost identical to the one posted by Viking earlier. The wing will fly as a KFM2 first. A KF strip will be added for KFM3 testing. The strip will be removed, the ailerons flipped (so the gap stays on the bottom), then the wing will be flipped and tested as a KFM1.

The wing has a rectangular planform and tip plates. Removing the plates and testing wing tip options is a possible later possibility.

Two other wings have to be built a KFM4, and conventional airfoil. The conventional airfoil will have the same profile as the KFM2 just continued with a smooth contour to the trailing edge. This airfoil is what Viking is approximating with his current KF3P test wing.

The Eagle Tree FDR can record prop rpm and motor current. This combined with airspeed, will allow me to fly the different wings at the same level flight airspeed and altitude, and record the current necessary to maintain that airspeed. The difference in current will be proportional to the drag of the wing when creating the same lift at the same airspeed.

I have no idea how long all this testing will take. It requires reasonably calm winds and many flights per wing. As much as I like to do engineering, there are a number of other airplanes I would like to fly as well. I'll keep you informed.

Roger
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Old Oct 01, 2010, 10:50 AM
High Altitude Flyer
viking60's Avatar
Fairplay, South Park, CO
Joined Sep 2005
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Roger,

Sounds like a great test approach! We'll be very interested in the data which you can log with your on-board test equipment setup.

VIKING
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Old Oct 01, 2010, 11:03 AM
just Some Useless Geek
Chicagoland
Joined Oct 2008
2,543 Posts
Roger, are you measuring true airspeed with something like a How Fast?
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Old Oct 01, 2010, 03:44 PM
Addicted to building...
Freddie B's Avatar
Omaha Nebraska
Joined Feb 2006
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Roger,

I really like you reasoning and approach. This data will be most welcome. I have stumbled into the confusion state which way to go with KFm in the near future, and this would help a lot so as not to duplicate your efforts at this time.

Fred
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Old Oct 01, 2010, 05:46 PM
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Useless, The Eagle Tree FDR is something like the How Fast. It records and also transmits the recorded data to a hand held receiver. The FDR records indicated airspeed. True airspeed will require manual calculation. My field is at about 70 feet MSL. If I fly the same indicated airspeed, keep the altitude low (say about under 50 feet above ground), and the conditions are not too different (pressure and temperature) the true airspeed will be very close to the indicated airspeed for all the tests.

My helper (wife) will be able to read the airspeed and altitude from the FDR and let me know how much I need to correct for a given pass. With sufficient passes at various airspeeds, I should be able to normalize the data, and come out with something useful.

The great thing about the Eagle Tree is that the data can be saved in a format that just about any spread sheet can process. I post my data on this thread, so it will be available to anyone who wants it.

I'm posting a couple photos of the new wing on the converted Slow Stick. The brass tubes sticking out of the leading edge are the pitot and static tubes for airspeed/altitude. The second photo shows the KF strip added top the wing to convert it from a KFm2 to a KFm3. The wing mounts were configured so that the KFm2 can be turned over, and it becomes a KFm1 without having to adjust the wing incidence angle.

Roger
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Old Oct 01, 2010, 06:41 PM
Jack
USA, ME, Ellsworth
Joined May 2008
17,131 Posts
Roger,

Have you flown the KFm3-SS hybrid yet? I have a not yet built SS and really would like to do something about the miserable wing it comes with, your project wing looks like a great idea.

Have you posted any details on your wing? Dimensions or any details on the spar or anything?

Jack
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Old Oct 01, 2010, 09:17 PM
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United States, MA, Tyngsborough
Joined Jun 2010
288 Posts
Plane testing

If you want to test a KF wing, mount it on uprights on the hood of your car, hang out a sunroof or a convertable. You can add fish scales to the up rights to measure drag and lift.

If you want to test while flying it, fly it infront of, beside or over the top of your car. In the latter case with a sunroof or convertable.

Find a good driver, a windless day and a companion to drive the car.

QED
(quod erat demonstrandum)
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Old Oct 02, 2010, 10:44 AM
fix-it-up chappie
tolladay's Avatar
Valley Village, CA
Joined Jan 2002
2,262 Posts
Quote:
Originally Posted by maguro View Post
Useless, The Eagle Tree FDR is something like the How Fast. It records and also transmits the recorded data to a hand held receiver. The FDR records indicated airspeed. True airspeed will require manual calculation. My field is at about 70 feet MSL. If I fly the same indicated airspeed, keep the altitude low (say about under 50 feet above ground), and the conditions are not too different (pressure and temperature) the true airspeed will be very close to the indicated airspeed for all the tests.

My helper (wife) will be able to read the airspeed and altitude from the FDR and let me know how much I need to correct for a given pass. With sufficient passes at various airspeeds, I should be able to normalize the data, and come out with something useful.

The great thing about the Eagle Tree is that the data can be saved in a format that just about any spread sheet can process. I post my data on this thread, so it will be available to anyone who wants it.

I'm posting a couple photos of the new wing on the converted Slow Stick. The brass tubes sticking out of the leading edge are the pitot and static tubes for airspeed/altitude. The second photo shows the KF strip added top the wing to convert it from a KFm2 to a KFm3. The wing mounts were configured so that the KFm2 can be turned over, and it becomes a KFm1 without having to adjust the wing incidence angle.

Roger
Nice work, Roger. Looks like you have found a way to bring more objectivity to KF airfoils. Maybe I should say, "good science." That is high praise where I come from.

Like many others here, I am eagerly awaiting the results of your data.
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Old Oct 02, 2010, 08:47 PM
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Test flew the SS today. It did pretty well. I need to change the prop out to get some more speed. I will have to change the motor out to get a lot more speed, but the wing works great. I mounted the FDR, but haven't downloaded the data yet. Nothing in the data will be of use for this project, but it will let me know how well the hardware is working.

Jack, here are a couple photos for you. They were taken to record how the pitot-static system was mounted, but they also show how the wing was built. I posted the info earlier, but the wing is a 41"x11" rectangle. The wing is built almost exactly the way viking posted in is cross section. A carbon arrow shaft is glued at the 30% chord point (where this wing has max thickness). A 1/" square hard balsa spar continues where the arrow stops. You can see this in the second photo. Viking uses one more foam spar than I did. His spar goes where the air hoses are. I didn't find it necessary. I glued the spar at the step to the top foam sheet. I did this so that I could make minor adjustments in location to make sure the curvature came out just where I wanted it. The ailerons are as close to full span as I could make them. The are made from 1 1/2" aileron stock.

You can see my wing template just above the wing in the first photo. I used the template to make sure the wing had the planned shape. Just a FYI, the template has the curvature of the conventional airfoil I will eventually use as a control.

I will post the maiden flight video tomorrow.

Roger
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Old Oct 04, 2010, 08:48 PM
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Here is the video of the maiden flight of the KF Stick. I have to say that this plane is fun to fly. I think I'll go through a lot of batteries doing "testing".

Sorry to say, that the FDR data was lost. Maybe next time.

Roger

KF Stick (4 min 7 sec)
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Old Oct 04, 2010, 10:15 PM
Jack
USA, ME, Ellsworth
Joined May 2008
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That's really a nice flier, Roger. I can see where you might have some trouble maintaining your scientific posture and slipping into some simple fun.

And thanks for the details too.

I can't see any aileron servos or hardware, are those (or is that?) mounted to the stick or on the bottom of the wing?

Jack
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Old Oct 05, 2010, 01:22 AM
Addicted to building...
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Omaha Nebraska
Joined Feb 2006
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Roger,

Cool seeing your video, but some requests. I've been flying my BB mod with KFm2 wing, and I'm trying to evaluate some general behavior related to the wing.

Wondering your take as a pilot on these issues. Rolls, and roll rate, plus behaior on shape, alltitude loss, etc. Roll with and without rudder assistance. Inverted flight. Turning radius acceivable without altitude loss. Aileron effectivness in steep climbs, level, and diving manuvers (differances). Aileron response in vertical climbs, like as in a stall turn, hammerhead, etc type climb. Adverse yaw with and without rudder assistance. Snap rolls (aileron, rudder effects, and spins, flat or otherwise. Complete stall, power on, power off?

Any reports welcome.

Fred
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Old Oct 05, 2010, 09:53 AM
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Jack, the aileron servos are under the wing just ahead of the step. The radio, FDR, transmitter, etc are attached to the fuse with lots of Velcro strips and straps. It's hard to see as it is all under the wing.

Fred, I've built five KF winged airplanes. Every one of them are different. Three had no ailerons. Well one (the BBAP1) I converted to ailerons, but with all the dihedral in the wings the ailerons were not effective. All three of these have KFm3 wings. Stalls are almost nonexistent. In my Blu-Guppy demo video I stalled the wing on landing. You can see the airplane get slower and slower, then it lowers its nose a bit and just keeps flying. If I did that with my other sailplanes I would have been struggling to keep them from hitting the ground.

My other two KF airplanes are KFm2 wings with ailerons. One is a 150% version of the SE5a designed by Tony65x55, and the other is the KF Stick. They couldn't fly more differently.

The SE5a is a drag generator. It starts out with a huge flat front, then adds two sets of wings, struts, etc. For a slow flier the SE5a climbs well, and glides like a dream. I shut down the motor when I start my base leg on landing, and still floats half way down the field before landing. The ailerons are very effective in that the plane rolls beautifully. At high angles of attack there is a lot of adverse yaw even with a lot of aileron differential. No matter what the bank angle the airplane will fly straight as an arrow. No turning tendency at all. If you want to turn it, you have to either bank hard and pull it around with elevator, or use rudder. With coordinated rudder turns are beautiful. Bank and yank turns loose altitude, coordinated turns do not. I even made some very tight flat as a pancake turns using full rudder. The rudder does not induce any bank. I only did one spin with the SE5a. I did it the way I taught my flight school students. Approach a level power off stall, as the stall begins to break apply full elevator and rudder and hold them. THe SE5a entered the spin and did three turns before I neutralized the rudder to stop the turn, and then leveled the plane and added power. It was a text book spin. No aileron was needed. I have done a couple of almost knife edge turns with the SE5a that were about a wing span in diameter with no apparent altitude loss. The SE5a doesn't so much stall as mush. It maintains the same attitude and just descends a bit faster. Stalls are done power off, as a power on stall results ends up being a hammer head or a tail slide (of sorts). Hammer heads require little or no aileron to keep the wings straight, just lots of rudder. The ailerons (all four of them) are effective up to the stall.

The KF stick is a totally different beast. The video above contains 99% of the flight time on this plane. I have two different levels of aileron differential on a switch. The lower level was what I used in the test flight. It seems to work great. I hardly touched the rudder on the test flights. With no dihedral at all, the ailerons are amazing. The plane hangs in the sky. Look at the landing. It wants to float. Add too much elevator and it gust sits there waiting for you to reduce it a bit. I have a lot more testing to do before I can answer all your questions, but for now my impression is: Wow. I am really looking forward to finding out more about how this wing handles.

Roger
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