|Oct 20, 2009, 10:16 AM|
You know I did that KFm3 build on the Zagnutz that is described here:
That build was the fruit of a detailed nine section HowTo that started at post #2215 of the Zagnutz thread.
After all of that, and some long weather delays and stuff I I had three very frustrating sessions of trying to get it to fly. It was rendered damaged beyond practical repairs at the last session and had not flown well at that point.
We (my much smarter FB and I) were battling a pitch sensitivity problem that we just could not get a handle on. We worked CG, the elevon deflection, expo, servo travel, etc., etc., trying to find a location that would stop the thing from doing these harsh transitions from pitching up or diving. Towards the end we had a point where we could get it flying fairly level but elevon deflection would turn that in to a sharp dive or climb. And that lead to the inevitable high speed impact that put it (and me) out of it's agony.
I had moved on to a KFm4 build by then and didn't look back at the KFm3 failure. Still not sure if it was me, the build, the KFm3, or what.
|Oct 20, 2009, 06:39 PM|
I had the same problems with a KFm3 on an earlier pod and boom pusher. I think the difference in lift between a good working KFm3 and KFm2 is minor and the forgiving qualities of the KFm2 by comparison make it the better option. KFm3 is the only notched foil that has ever given me problems.
To quote a former infamous President: "I feel your pain."
Got some flying time in with the Buzzard yesterday and Tata did his first launch and first "real" solo. Seriously, his landings are better than mine!
Build thread has been started.
New vids posted 10/21/09
|Oct 21, 2009, 06:49 AM|
Isnt it nice when youve got your plane flying that well all the time...really nicely sorted that Buzzard
Tata nearly had that hand catch... the younger fliers pick the game up so much easier than us oldies.....
|Oct 21, 2009, 05:57 PM|
Thanks for the comments and support Guys,
Tata is doing very well for a newbie and We got the van back so we can take a couple of planes out later. I plan to see if he can handle the Assassin.
I will start on the second Vesper today, Lord willing and the creek don't rise! When it's done we will see if Tata can handle it. While I build I'll be adding pictures and info to the Vesper build thread.
I have an order on the way from HK and when the stuff gets here I'll set up a plane on the second HK 2.4G TX and then we can fly two at the same time.
Heres the latest video's on the KFm2 Vesper. Hope to get more flight video today as well.
BTW: I ordered a small EDF to just play around with. do any of you fly the ducted fan models? Anything I should know?
|Oct 22, 2009, 01:29 AM|
Ipoh, Perak Malaysia
Joined Jul 2006
One thing you should keep in mind with EDF models is that the acceleration is nowhere as good as with a prop plane. Don't think you can goose the throttle and expect the plane to respond immediately with a burst of speed to get you out of trouble. Unless, of course you have a very over-powered EDF system.
|Oct 22, 2009, 01:39 AM|
|Oct 22, 2009, 04:34 AM|
Just to play with. I figure I'll design a 24"span floaty jet- type flying wing around it. Small light KFm2 and try to keep the airframe weight down really low. I also have a gyro on the way but the way the Vesper is flying I don't think I'll need it. At least not for that plane.
We had a pretty good morning flying today and when Edna got back from the Market this morning she had two boxes from Hong Kong so now I have the new 2.4G TX. Christmas in October!!! I have it set up on the Buzzard for Tata so we can both fly at the same time now. Maybe we can see how that works out tomorrow if the weather cooperates.
I have installed a big 3s Lipo in the new TX like my other one and I numbered them on the front for for clarity. See pictures. I love it when packages arrive. I also got 3 Turnigy 1300mah lipos because all my Zippy Litemaxs are puffing. I won't buy them anymore. They cost me 12 bucks each and the Turnigy has the same capacity at higher discharge rate for around 8 bucks each.
Well maybe tomorrow I can start a new Vesper. I think Tata can handle one and it would be nice to have two of them up at the same time. Besides I need to photo the construction for the build thread.
Things are good and I'm staying busy.
BTW: Tata flew the Assassin 36" KFm4 on the lower rates and did OK. Only problem was when he tried to catch it while I was landing and it carwheeled and busted up the tip but 5 minutes in the garage with the hot glue gun and it's ready to go again.
Thanks for the positive comments on the videos. I think more people will come around to flying KF notched wings when it gets more known how well they fly.
|Oct 22, 2009, 11:49 AM|
Joined Oct 2008
Learning how to catch a landing plane is a skill that is acquired through lots of broken FFF. My technique is to come in low, then come up to head height as I cut back on power. I've seen video of one guy who consistently comes up and stalls right in front of his hand, but I could never do that in a zillion years.
One thing for sure: the KFm2 makes catching much easier because of the reduced stall speed and higher AoA. I wonder if everyday sport flyers will adapt it just for that reason...?
|Oct 27, 2009, 12:43 AM|
Second Vesper ready for maiden.
Vesper #2 is ready to maiden and the build thread is ready for viewing.
This differs from the original Vesper in that the use of EPE for a pod-skid and for the tip plates should make it a bit more robust. I used a larger battery to get the balance right and I provided much more ventilation for the gear. I expect the flight characteristics to be much the same as the airframe shape is not changed at all.
Any comments and suggestions on the build-thread would be appreciated. It's the first one I've attempted and I think it illustrates some creativity in "use of materials" in third world countries.
Lee mentioned in an earlier post about the Plank-roll and Plank-loop problems. In an effort to keep the basic design, which I like, and to improve the handling I'll be doing a Mark II version with more sweep.
As is, it's quite flyable as long as you don't go crazy with "Crank 'n Bank" type flying and extreme throws. It's not a beginner's plane but I find it fun, if a bit tricky in the wind. 20% MAC CG is 4.2" but I find that 3.75" to 4" on the original makes it better behaved. Too rear a CG and it becomes a handful fast, and over controlling becomes a big issue then.
I like the looks a lot and minor mods should make it a bit more pilot friendly.
|Oct 27, 2009, 05:38 AM|
I have now found another NO-NO for these wings
....The HO229 wing maiden shows it is a poor flyer, yes it flew but had some problems, all down to how I built it
I used steps and wing thicknesses the same as a previous wing that was ok, but forgot just how narrow a wing the HO has...
With a tip chord of only 4" and a depth of 30mm ...the ratio of depth to chord has made the wing go poorly...depth 30mm chord 100mm ..30% does not work...
a poor result so watch your %ages
Steve I think this could apply a lot to your builds, as you have to make thick wings because of your materials.. What are your %ages for the good wings, and have any turned out poor?
BTW... an excellent build thread for your Vesper
My previous wings that did work well are
.... a sloper with ...same 30mm thick wing at 14% depth/chord at the tips down to 10% at the roots ..tips 210mm root 280mm ...glides very well
.. and Zagnutz 25mm thick wing......10% at tips ..8% root.... flys and glides very well.
So I thought 30mm would be ok again....BUT it wasnt...I must admit I looked at the ends and wondered if it would be ok, because they looked too thick and out of proportion...
Vikings work shows a 10% wing is good as a guide target...less = faster ..more = slower..
So Ive got to chop the wing to reduce the %ages and fly again..
Considering how far off my %ages are its a wonder it flew as well as it did..
|Oct 27, 2009, 08:37 AM|
Interesting reading Dave, you and Steve have down so many different things and know so many details.
I'm sort of wondering how we can better describe or express some of the basic factors like chord, step height, wing thickness, step location, etc., with an eye to preserving the details. That would help us see or know what was actually built as we read about how it flies. Maybe help us get a feel for what the traits or effects of the variations are.
How can we express that better in our posts here so that it is easier to summarize the details of he various builds? A detail summary or one line statement for one wing half that says more about the build? Maybe something like:
KFm variation-half span/Root chord/Step location/Step height/Root Thicknes/Tip chord/Step location/Step height/Tip Thickness
This would be my KFm4 Zagnutz:
Is a description like that a little too unintelligible?
Maybe something like this would be better, it would be more self explanatory:
KFm4-half span: 24"
Root chord: 11"
Step location: 5.5"
Root thickness: .75
Step height: .25"
Tip chord: 5.5"
Step location: 2.75"
Step height: .25"
Tip thickness: .75
Or have I crossed the line on unnecessary details here. I do enjoy reading all the numbers...
|Oct 27, 2009, 10:18 AM|
When we do a build all that info definately needs to be included. But whatever we include someone else will build as they like to, rather than as we did...
A long description like that first would loose me.. I could never remember the order of info..so KFm4 is about what I would read..
but a complete spec list should always be included.. with extra details on AUW ..Area.. motor, prop battery etc... As much info as possible at the start of the build is best
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