Divinity, 42" KFm4 Slowfying wing. - Page 2 - RC Groups
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Mar 28, 2009, 03:57 PM
Jack
jackerbes's Avatar
ApachePilot,

I messed that up, I need to change the parts drawing to show that four (4) KFm strips are required, two each for the top and bottom.

I'll fix that soon.

And I'll also change the parts drawing to show the full, both sides, wing panel and also a full, both sides, KFm strip. I'll put a dashed lines on the center line on those so that people can make either a full or half template.

The evolution of getting the plans right and getting me trained as a CAD draftman continues...

Jack
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Mar 28, 2009, 04:02 PM
Is it SEFF yet?
reg3's Avatar
Yep, it clears it up. Your drawings need to change to show 4 of the strips required.
Mar 28, 2009, 04:12 PM
Is it SEFF yet?
reg3's Avatar
I must really type slow. Maybe I shouldn't watch TV and look at the laptop.

I wonder how it would fly with the strip only on the top? Have you tried a version built that way?
Mar 28, 2009, 08:31 PM
Jack
jackerbes's Avatar
With only the top strip it would be essentially a KFm2 wing and those have a history of flying fine.

It pretty much boils down to that someone has to try it and then report the results here. Of course, if your going to do that you should build one with the bottom strip and one without it in order to have some basis for comparison. :>)

ApachePilot's wing is essentially a KFm4 wing as far as the arrangement of the parts because it has the strips top and bottom. As originally defined the KFm4 strips are location at 50%, ApachePilot placed his at 40%.

KFm wings seem to tolerate variations in step placement and height. The is no clearing house or laboratory for defining and categorizing the various builds, there are no rules, and there are certainly no KFm police making sure everyone is "doing it right".

But the most common reference for the various builds is the figure here:

https://static.rcgroups.net/forums/a...20Airfoils.jpg

from post #1 of the ** Kline-Fogleman Airfoiled Flying Wing ** thread which is located here:

https://www.rcgroups.com/forums/showthread.php?t=558321

Jack
Mar 29, 2009, 06:22 PM
Father Francis, formerly Apach
New world-view PDF uploaded and edited to post one.
Thanks, Jack....


ApachePilot
Mar 29, 2009, 07:35 PM
John 3:16
Daddy-O's Avatar
Great job on that pdf Jack! Looks great! I'm going kayaking tomorrow, but am planning on starting my Divinity this week. I think I am going to use some 5mm epp that I have sitting around. It's either that or 1/4" blucore. I think the epp will be stiff enough with a couple of cf tubes in it. I want to keep it light and floaty.
Daddy-O
Apr 06, 2009, 07:05 PM
Father Francis, formerly Apach
Anyone else build their own Divinity wing yet?



ApachePilot
Apr 06, 2009, 08:55 PM
John 3:16
Daddy-O's Avatar
I was sick all week last week, and didn't get to it. As a matter of fact, I didn't do much of anything at all. I think I'll have time to get mine started this weekend. I'll take pics and let you know how it goes.
ApachePilot, what is this I hear about you working on Divinity 2? What is that going to be?
Daddy-O
Apr 08, 2009, 11:00 AM
scrapy scrapy doo.
roonroon's Avatar
Hi Apachepilot,

Nice one to build next after the Tribal.
I was looking forward to it and was buzy with other things.
Still no Tribal maidenflight due to bed weather on this side of the pond.

Thanx Ron
Apr 08, 2009, 11:19 AM
Father Francis, formerly Apach
Quote:
Originally Posted by roonroon
Hi Apachepilot,

Nice one to build next after the Tribal.
I was looking forward to it and was buzy with other things.
Still no Tribal maidenflight due to bed weather on this side of the pond.

Thanx Ron

Ron, no problems here...

The weather hasn't been very cooperative this side of the pond either...So....it just gives me more time to design/build. I have a DLG wing I designed ready for electronics. I had to order them online, so it is taking longer than I like. Until then I have another wing design I will begin building later today. 30"span and will be called, (the humming bird).


Keep us all informed...

ApachePilot
Apr 09, 2009, 07:46 PM
Father Francis, formerly Apach

How is this possible? Divinity surpasses the 1 hour mark!!!


I just came in from a very interesting flight with Divinity. I have come to realize that Divinity has thermaling qualities. At 6:30 pm tonight I decided to go out to the back yard and have an enjoyable flight with Divinity. I seen a few birds circleing overhead a hundred yards out or so and about 400-500 feet high. I thought I would send Divinity out to see if I could find the thermal which I knew those birds had to be riding. Well, I found it.... After about 2 minutes climbing in a large circle staying under the birds, I cut power. Long story short, my neck is stiff!!!, I must have found a notorious boomer or something, because Divinity remained aloft for (1 hour and 6 minutes)!!!...That's right...you heard it.... A couple times I had to strain to see her and had to dive until I had better orientation....How is this possible??? I am only using a 430mAh 2s lipo.....my battery is on charge right now and I will keep time on how long it takes to recharge, but....I still want to know how???? I think I need a larger battery if I am going to attempt this again....

Answers/suggestions welcome.......charging took 25 minutes to replentish the pack...


ApachePilot
Last edited by ApachePilot; Apr 09, 2009 at 08:49 PM.
Apr 09, 2009, 09:04 PM
Registered User
Dickeroo's Avatar
Quote:
Originally Posted by ApachePilot
I just came in from a very interesting flight with Divinity. I have come to realize that Divinity has thermaling qualities. At 6:30 pm tonight I decided to go out to the back yard and have an enjoyable flight with Divinity. I seen a few birds circleing overhead a hundred yards out or so and about 400-500 feet high. I thought I would send Divinity out to see if I could find the thermal which I knew those birds had to be riding. Well, I found it.... After about 2 minutes climbing in a large circle staying under the birds, I cut power. Long story short, my neck is stiff!!!, I must have found a notorious boomer or something, because Divinity remained aloft for (1 hour and 6 minutes)!!!...That's right...you heard it.... A couple times I had to strain to see her and had to dive until I had better orientation....How is this possible??? I am only using a 430mAh 2s lipo.....my battery is on charge right now and I will keep time on how long it takes to recharge, but....I still want to know how???? I think I need a larger battery if I am going to attempt this again....

Answers/suggestions welcome.......charging took 25 minutes to replentish the pack...


ApachePilot

That is an amazing experience you've just had. You might need a lawn chair or something where you can lay down so you won't be straining your neck. I'm sure this is a day you'll never forget. Congratulations and thanks for sharing this with all of us.

Dickeroo
Apr 09, 2009, 09:35 PM
Jack
jackerbes's Avatar
Let do the math and see if we can figure it out.

430 mAh = .43 Amps
.43 Amps x 60 minutes = 25.8 Amp minutes

The E-Flite 180 you are using draws about 2.6A max continouse. That would give you 9.9 minutes of continuous full throttle time. (25.8 / 2.6 = 9.9 minutes).

You motor is obviously what will use up the most power. The two minute climb at 2.6A would have used up 5.2 Amp minutes leaving your with 20.6 Amp minutes.

Your receiver and servos are less of a known but we can estimate it. One of my planes with a JR R6UL receiver and four servos draws about 0.13-0.16A setting idle. If I move all the servos it will jump up to 0.22 to 0.29A for a fraction of a second and then drop back down to the idle draw.

Let's say your plane with a smaller receiver and two smaller servos draws half of what that one of mine did. That would 0.08A idle and maybe 0.14A peak. So lets say your receiver and servos draw 0.11A continuous for the 66 minute flight. That will use up another 7.3 Amp minutes or so (0.11A x 66 minutes = 7.26A).

So now you have 13.3 Amp minutes left. And those last you for the remaining 64 minutes of the 66 minute flight.

If you were at 1/4 throttle and the motor was drawing 1/4 of the 2.6A max, it would be drawing 0.65A per minute. And that would only be about 5 minutes of motor on time at 1/4 throttle (13.3 Amp minutes / 0.65A = 5.07 minutes).

Were you using the throttle that little? Was it off nearly all of the time? Or did you only use about 5 minutes of 1/4 throttle on during the last hour or so? If so, then it is all pretty well accounted for.

Do you know how much the battery took on the recharge? How many mAh?

Jack
Apr 10, 2009, 07:34 AM
Father Francis, formerly Apach
Jack,

Thankyou for doing the math...

Flight went as follows:
I plugged in the flight pack and looked skyward for any signs of wind up top ,(looking at the trees) and a few birds caught my eye..Ravens, or so they looked...
That is when I decided to explore Divinitys capabilities. I launched as I normally do at 1/2 throttle and started a casual climb of 15-20 degrees or so for 2-1/2-3 minutes at which point I cut the throttle...
No motor ws used for the remainder of the flight until landing approach. At this time there were a few short burst just to maintain altitude and heading, setting up for landing in my back yard. 15 seconds total throttle usage during this approach. At touch down I unplugged the lipo and found it slightly warm. I waited 15 minutes for it to cool and placed it on charge setting to .5 amp. Total charge took 25 minutes to rebuild the pack.


With that, the pack is ready for another sorte, and the wind is non existant... I love being a early riser....


ApachePilot
Apr 10, 2009, 08:57 PM
John 3:16
Daddy-O's Avatar
I've decided to build this with blucore instead of the epp that I have. I don't see any reference to a spar for this plane, so I assume that the original was not built with one, right? I should get it built tomorrow morning. No promises for the electronics though. I have quite a bit to do tomorrow, so I am squeezing in the build. I expect to maiden it on Monday morning. I'll try to get a video of the maiden flight. No spar, right?
Daddy-O


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