48" Divinity II Build***Now with Proof of flight video*** - Page 2 - RC Groups
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May 13, 2009, 06:16 PM
Father Francis, formerly Apach
Well,

I finally made it to the post and returned after a little shopping.

Here we have the final AUW of Divinity II without camera system.

I still have room to grow....


Enjoy!


ApachePilot
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May 13, 2009, 06:54 PM
Radio Up Flyboy!
flynfrog's Avatar
ApachePilot,
thank you for your reply. May I ask for additional clarification please. From your desctiption above, your final step configuration from the Root of 16" is 25% (4") & 50% (8") with a base of 16" (100%). 25% / 50% Top & Bottom.

Is this the same configuration as you Divinity I?

Looks like there is an expansive amount of ingenuity and tolerance in the KFm series (KFm3 as used here). I have discussed this many times with Dickeroo over the last several years. The initial KFm3 had steps at 50% & 75% leaving room for a 25% aileron if size dictated.

Your Divinity I & II designs are very clean and pleaseing to the eye. The videos proves that the planform is stable. Congrats !!

Flynfrog
May 13, 2009, 07:42 PM
John 3:16
Daddy-O's Avatar
ApachePilot,
It looks great! The only thing that was lacking in that second picture of Divinity II on the scale was my zip code on the monitor. Your decals and lettering look great also! I'm looking forward to seeing the proof of flight video. What ever you do, don't crash it. It looks too good to crash.
Daddy-O
May 13, 2009, 07:54 PM
Father Francis, formerly Apach
Quote:
Originally Posted by Daddy-O
ApachePilot,
It looks great! The only thing that was lacking in that second picture of Divinity II on the scale was my zip code on the monitor. Your decals and lettering look great also! I'm looking forward to seeing the proof of flight video. What ever you do, don't crash it. It looks too good to crash.
Daddy-O




Thanks Daddy-O,

Keep checking back, there could be a Divinity II coming to a theatre near you....

OK, at least some plans so you could build your own.....
Proof of flight video will come as soon as we have an hour of good weather


ApachePilot
May 13, 2009, 08:00 PM
Jack
jackerbes's Avatar
ApachePilot,

I think Flynfrog is talking about what the percentage of the chord the wing thickness is at each of the steps.

Maybe I can answer his question. Since you are using 4mm/.158" thick foam (foam board with the paper removed) so the total wing thickness would be 20mm/.787" (five layers of foam) at the back of the first step and 12mm/.472" (three layers of foam) at the back of the second step.

"..Would you please post your KFm6 (9%-6%-3%) at (50%c-75%c) specs? I am courous about the total Airfoil thickness with both Top & Bottom steps. example: at the 50% chord position, at 9% - the effective airfoil thickness is 18%..."

ApachePilot tells me the chord (tip of nose to prop slot) on that is 14-1/2"/368mm so the wing thickness percentages at the steps would be about as follows:

25% step = 20mm high = 5.4%
50% step = 12mm high = 3.3%

The wing center panel or elevons at the prop slot or trailing edge are not considered a step if that is what your third percentage is. But the thickness there would be 4mm or the thickness of a single layer of the foam.

"..My thoughts were to Combine a Top KFm3 with a Bottom KFM1 (single step @ 40%)..."

I don't know that anyone has done that yet or, if they have, if it has been mentioned here. There is no real formal record keeping or archives for KFm details beyond what happens to be discussed and recalled here.

If you try that combination of steps, fill us in on the details as far as how it was built and how it worked if you can. We are always glad to hear more and learn more about the possibilities of the different variations.

"..Are your KFM3 steps 3% apart (9%-6%-3%)?..."

The percentages more result from the combined thicknesses of the materials used (spars if any, layers of foam, etc.) than an attempt to keep them in even percentage increments.

It is another one of the variables to be explored but we've generally found that the KF and KFm airfoils are very tolerant of variations in the step heights and locations. It is almost that nearly anything will work but some things work better than others. And that varies with type of plane and other factors too. A lot of it just has to be figured out for yourself as you build and modify and rebuild. That sounds harsh but it is not intended to sound that that way. :>)

Jack
Last edited by jackerbes; Sep 18, 2009 at 07:01 PM.
May 13, 2009, 10:27 PM
Radio Up Flyboy!
flynfrog's Avatar
Jackerbes,
Thanks for the reply.

I do have some history with the KFm & KFm1 airfoil over the past 3 years. My first introduction was in converting my EPP flat plate 3D plane to the KFm1 (Bottom Single Step 40%) & Then to the KFM2 (Top Single Step 50%). The ship was now stable & gained a Longer glide ratio. Then came the Revert flown at over 8000' ASL, followed by Hells Canyon (6800' ASL) in winds ranging from 3-45 MPH. Again Stable and Stall Free.

At the beginning of the KF thread there is a spreadsheet for calculating the Step height for a given Chord & Sheet thickness. (https://www.rcgroups.com/forums/show...r#post7578976). Later on in the thread is a revised version with cleaner interface. I would like to expand on the spreadsheet to Calculate & Graphically Chart (draw) the different versions of the KFm#. Hence the questions on Step % Percentages.

The KFm# is my airfoil of choice, even though I have a Hotwire CNC Foam Cutter. I would also like to Massage / morph a Standard (non-flat plate) airfoil to include the various Step configurations. It will most likely be an RG-15 (or similar series) airfoil using the Leading & Trailing edges & placing steps in between.

As we have seen, there are few Design / configuration limitations in a flyable KFm# Airfoil. Stable, Stall Resistant, Great glide & Lift capabilities, & of course - a user friendly easy to experiment & build Airfoil.

Flynfrog
Last edited by flynfrog; May 13, 2009 at 11:03 PM.
May 14, 2009, 08:55 AM
Father Francis, formerly Apach
Good morning gentlemen,

I couldn't resist, so last night I added a small bit of color to the bottom of Divinity II so that it would be easier to see up top. Yeah, I have a small bit of confidence in my building. At least I hope it will fly, but the weather is holding me back right now. Also I sealed all the foam and covered all the lettering and decals with a light coat of puzzle saver. I am hoping that that will eliminate any moisture problems with landing an tall damp grass covered with morning dew.

AUW weight came in at 364 grams or 13 ounces RTF without camera equiptment. My first motor to test is said to produce 400+ grams thrust using a 11.1v lipo and 10x3 prop, (which is what I have) so we will see.
Set up as is, I get nearly 3 full inches of travel on my elevons at full deflection, but that is neither here or there. I have differential set to 40% so I am hoping to get a more axial roll out of a flying wing, rather than a sort of barrel roll. I have cut the winglets out of white coroplast to replace the foam ones installed hoping they hold up a little better on landing in less than perfect conditions.

We are ready for flight here; just waiting for a call to launch....

Count down timer has been set and all systems are a go.


ApachePilot
May 14, 2009, 10:15 AM
Registered User
Dickeroo's Avatar
Looking very good, ApachePilot.
May 14, 2009, 10:17 AM
Registered User
3D-Flyer Kevin's Avatar
It does look *REALLY* nice. I can't wait to hear/see how it flies.
May 14, 2009, 10:46 AM
Huge field, little tree... WTH
Danoman812's Avatar
Hey ApachePilot...
I liked your design so much that I'm working on the build myself... only, I'm making mine in the micro version. I've taken your original version (Divinity I) dimentions and have reduced it down to the wingspan of 16". This should be an interesting build... hahaha. I've added your ideas here as far as the wing build-up but, of course in the reduced state. I'll let you know more as I go if your interested.
Hmmmm... I don't think mine will be quite as quick as yours will be. Hahahaha... Looking forward to seeing some pics and vids on the performance of that machine you got there...!!!

Dano...
May 14, 2009, 01:06 PM
Jack
jackerbes's Avatar
Looking good for sure!

Scene: Early Spetember in 1918, on The Western Front, at an aerodrome west of the Saint-Mihiel salient, just at sunrise:

The steely eyed airman stands quietly outside the hanger, polishing his goggles and pulling on his gloves and flying helmet as the ground crews rolls the plane out. He takes a couple of swallows of blackberry juice because that is supposed to reduce the diarrhea from breathing the castor oil fumes in the prop wash. Even the best steely eyed airmen can be distracted by by diarrhea while on a combat patrol. A young Sergeant approaches the pilot, salutes, and says "your plane is ready, Sir." The pilot fights back his nausea and returns the salute, then turns and walks toward his plane...

Jack
May 14, 2009, 03:07 PM
Registered User
Dickeroo's Avatar
Quote:
Originally Posted by jackerbes
Looking good for sure!

Scene: Early Spetember in 1918, on The Western Front, at an aerodrome west of the Saint-Mihiel salient, just at sunrise:

The steely eyed airman stands quietly outside the hanger, polishing his goggles and pulling on his gloves and flying helmet as the ground crews rolls the plane out. He takes a couple of swallows of blackberry juice because that is supposed to reduce the diarrhea from breathing the castor oil fumes in the prop wash. Even the best steely eyed airmen can be distracted by by diarrhea while on a combat patrol. A young Sergeant approaches the pilot, salutes, and says "your plane is ready, Sir." The pilot fights back his nausea and returns the salute, then turns and walks toward his plane...

Jack

Geeeeeeeez.... was that when they invented diapers?
May 14, 2009, 06:08 PM
John 3:16
Daddy-O's Avatar
Quote:
Originally Posted by Dickeroo
Geeeeeeeez.... was that when they invented diapers?
Hahahahahahaha! That is soo funny!

Daddy-O
May 14, 2009, 09:09 PM
Father Francis, formerly Apach

Divinity II, a success!!!!


Tonight the wind died down about 8:00 leaving me about a half an hour of daylight. I had the battery charged for the new Divinity II wing so I called my camera man and told him the deal. We met at the local elementary school field, I will let the video say the rest.



I hope you enjoy.

Divinity II Maiden flight, a success! (7 min 3 sec)



ApachePilot
Last edited by ApachePilot; May 14, 2009 at 10:02 PM.
May 15, 2009, 02:04 AM
Radio Up Flyboy!
flynfrog's Avatar
ApachePilot,

Congrats on another successful design. How would you compare the flight characteristics of the Divinity I & II designs? And to what do you attribute the flight differences?

Flynfrog


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