Regal - w/KF Wing (Video, Pictures, Free plans, and Discussion) - Page 11 - RC Groups
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Aug 29, 2007, 07:29 PM
my nCPX is my sim!
30v2's Avatar
Originally Posted by bubbafusion
I was wondering, has anybody built the same basic plane, but with three wing styles; flat plate, KF, and a regular shape? I've seen lots of videos on this site of planes with flat-plate wings and regular airfoils that fly just as well as the Regal. To be the devil's advocate, I was wondering if the extra weight and complexity of the KF has been shown to be worth it.
Actually, there is little extra weight with the KF wing and it is very simple to make once you figure out the right amount of step. Since Kaos has already done that part, this is pretty easy to put together and is MUCH cheaper than buying cf stock to strengthen the wing. And IMO you end up with a wing that is just as strong as any other (if not more so). Also, concerning the weight issue, the KF wing may produce more lift than those other airfoils, which would actually improve flight performance despite any weight penalty.

Now I'm not arguing that there are not other designs that fly just as well, (because there is a lot more to a good design than just the airfoil) but there seem to be advantages in the performance we are experiencing with the KF airfoils. If you add that to the fact that one can produce a larger plane without spending money on cf to re-enforce the wing, this design seems to have advantages that others do not.

Just my 2 cents...

As to the first part of your question, I'll leave that to Kaos to answer.
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Aug 29, 2007, 08:38 PM
Heli's don't fly voluntarily
Kaos2's Avatar
Originally Posted by bubbafusion
I was wondering, has anybody built the same basic plane, but with three wing styles; flat plate, KF, and a regular shape?
Bubba, excellent questions. I've posed the same type of questions on the Kline-Fogelman Flying Wing thread, and it appears that I have been ignored. Further support for your question comes from the fact that foam planes don't really fly like regular planes. Nobody in their right mind would consider a flat plate wing for a 40 size nitro plane (4 - 6 lb.), much less a full size aircraft (1500 lbs and up). By "regular airfoil" I assume that you mean a Clark-Y type. When speaking of the Clark-Y airfoil, that’s another airfoil like the UC that has very poor inverted performance, so it’s not in consideration for a Regal type airplane.

As to your concerns about weight, cost, and complexity, the KF airfoil compares extremely favorably. I’d bet that a spruce spar CA’d to the KF wing will weigh very close to that of a flat plate with carbon fiber spars epoxy’d in place.

Cost of a KF spruce spar is way cheaper than carbon fiber, so KF wins the cost category hands down. Also, if building 33” or less, you can use even cheaper balsa for spar material.

Now for complexity. Once you know what you're doing building a KF wing, they are one of the easiest, fast build wings out there. Installing CF spars to a flat plate is just as time consuming as installing the spar and top skin to a KF wing. I won’t bother to address build differences for UC wings since they don’t have any inverted performance to speak of.

To my knowledge, nobody has performed the tests you've described to date. You may find it interesting to know that I've designed and built an experimental test-bed plane (X-TB) that I plan to fly with various wings. This will allow the direct comparison of different airfoils on the exact same aircraft. I have the plane 90% complete (waiting on hardware to arrive), and (2) wings already assembled for testing. I will be conducting a variety of comparison tests and will be documenting the results with pictures, video and notes. When my tests are complete, I plan to share what I discover. Watch for a thread about my X-TB in the future.
Aug 29, 2007, 08:55 PM
Registered User
bubbafusion's Avatar
Thanks for the answers guys. I look forward to hearing what you find out using the X-TB.

What I meant by regular airfoil was some type of symmetric or semi-symmetric wing. I've built several of them, mostly for scale planes, and they all fly well inverted. I even have one 3D plane with a symmetric airfoil, and it's a great flyer. I'd still argue that you can't beat flat-plate wings for ease of construction. What could be easier than taping a CF rod or other reinforcement to the wing? Also, I recycle my CF through planes as I crash or tire of them, so it doesn't cost that much in the long run.

I'm a scientist (experimentalist) in real life, so I like to see some data. I find the KF wing intriguing and look forward to learning more about it, and appreciate your kind replies, hard work, free plans, and instructive comments.
Aug 30, 2007, 07:26 AM
Registered User
Kaos -

Kaos -

I wandered over here from the BB thread. Curious, as I look down the road, would the Regal make a good aileron trainer or would the BB with ailerons work better? Since I can't fly a 3 channel plane well (yet) my question is hypothetical, but an old guy can dream (zzzzzzzzzzzz) ...
Aug 30, 2007, 09:35 AM
Heli's don't fly voluntarily
Kaos2's Avatar
Originally Posted by elight50
Kaos -

Kaos -

I wandered over here from the BB thread. Curious, as I look down the road, would the Regal make a good aileron trainer or would the BB with ailerons work better? Since I can't fly a 3 channel plane well (yet) my question is hypothetical, but an old guy can dream (zzzzzzzzzzzz) ...
The answer to your question depends on where you are with your personal flight experience and skill. The Regal is designed to go where you tell it to go and, keep going that way untill you tell it to do something else. If you're past the point where you need a plane to try to level itself for you, then a Regal with reduced control throws could be a good option for your next step. You certainly won't need to be a great pilot to fly a Regal. You just need to be to the point that you're happy with a plane that does exactly what you tell it to do. The good thing about building a Regal is that you'd have a different type plane to fly and, one that you can increase the throws on as your skills develop.

Personally, I believe that it's in a person's best interest to learn to fly 4 channels right from the beginning. After people have had a bit of practice on my flight sim, I've been handing my aileron equipped BB to them to fly. Numerous people who have NEVER touched a RC plane before are able to fly circuits with my aileron BB with no problems. Ailerons are no big deal, just a basic function!
Aug 30, 2007, 12:32 PM
Registered User


I need to retire. I have so much to do - maybe a nap first?

Thanks Kaos -

Sep 01, 2007, 04:11 PM
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davereap's Avatar
I had another flying session with my 33" span version today..the winds were even worse than before. At 10oz AUW I was getting hammered. BUT no problems, the controls are well responsive, (still on down rates).
It was a good session for position recovery practice.
The forward speed at half throttle was stationary, but it penetrated well on full power.
The rudder is very effective, it flat turns in about a 6 foot diameter at half power.
Stall turns are a laugh, coming about in its own length.
Inverted needs just a touch of down, the cog is about 1" in front of the step
Knife edges will be ok as giving slightly too much rudder gave an easy climb, but there was much too much wind to get good results today.
all in all a good session

I am now thinking of building the 40" version, aiming for a heavier plane to cope in these winds we have been suffering with all this year

If you are thinking of using this as an aileron trainer, build it with the wing moved up to shoulder level, keep the radio low in the fuz, and dial the control movements down.
The low build cost of these depron models makes them ideal..You can have built four or five of these for the cost of a 40 size trainer
Last edited by davereap; Sep 01, 2007 at 04:25 PM.
Sep 02, 2007, 06:36 PM
Heli's don't fly voluntarily
Kaos2's Avatar
Dave, it sounds like your Regal is as responsive as I'd expect it to be. I can't wait to hear about a flying session after you've tried it in calm air. Sounds like you're having fun.
Sep 03, 2007, 07:29 AM
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davereap's Avatar
Yes its a great little plane to fly...and is very quiet compared to most of my others..
the only problem is our english weather this year, too much wind even on a nice day.

Never mind a bigger and heavier cat version is already being built..I just love this plane....this one will be painted in a suitable american color scheme.

pics will come..... cheers dave
Sep 08, 2007, 08:43 PM
Wuwu's Avatar

Thanks for the plans!

...Is anyone building the Regal? ...
Yes, me too.
...Nigelp - Would love a set of tiled plans - problem is, the only place you can buy 'letter size' paper is in the USA. The rest of the world uses A4 !
Yes It's True.
Wingspan - 38". Why? Because ... A4.
Temporary powered by TP 2409-21 + GWS 8040.
Few pictures of my Regal.
Sep 08, 2007, 10:40 PM
Registered User
I'm almost done with my 40" Blue-Cor Regal. All that remains are some final painting, wheel and motor installation, and final control surface linkages.

I'm concerned about CG, however. AUW with 800 mAH 3S Lipo and Eskay 400X motor is about 17 oz. CG is about at the spar, so I need about 1" further to the front. I plan to order a 2410-09Y outrunner, which will add about .5 oz more to the nose. But that is not enough to get the CG right where it should be (1" ahead of the step). At 17+ oz already, I hate to add ballast weight to the nose, which could take me to 18-20 oz. But that may be all I can do to get the CG right.

Any suggestions Kaos2? You know best about the flight characteristics of this plane.

BTW, nice job WuWu! Any specs, AUW, CG, etc? Be sure and give us a flight report.

Sep 08, 2007, 11:21 PM
Heli's don't fly voluntarily
Kaos2's Avatar
Wuwu, your Regal is looking great! That's some good picture documentation of your build. Can't wait for a flight report.

Nigelp and others, I'm having some PC problems right now with my desktop unit. That's the PC with CAD so, until I get things squared away with that machine I won't be able to help provide a set of A4 plans. Sorry.

van-c, sounds like you're really coming along nicely with your project. As far as the CG is concerned, I would want to have the CG at least 1/2" ahead of the step (for the bare minimum maiden flight). The Regal likes a more aft CG than a tradition winged plane due to the KF wing, but I'd be more comfortable with the 1" ahead of the step CG location for a maiden flight. Temporary weight in the battery compartment should permit this setup. The Regal was designed around a 1200 - 1320 mah Li-Po (3.5 - 4 oz.) and a 2410-09Y motor. Mine came out at 17.4 oz. AUW after the painting. There's a ton of wing area, so the plane should be able to carry a bit of extra weight easily. Also, at 17.4 oz, the plane hovers at about 2/3 throttle. Again, there's plenty in reserve to handle a bit of extra weight for a maiden flight. Once the maiden is out of the way, start removing the extra nose weight until you find the "happy spot".

One more thing. This plane is designed to be very maneuverable so, be careful with your control throws until you get accostomed to her flight characteristics. Davereap has been testifying to her responsive nature!
Old Sep 09, 2007, 12:46 AM
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Sep 09, 2007, 01:30 AM
Registered User
Kaos2, thanks for the pointers.

After cutting out a hole in the former at the front of the battery compartment, I was able to slide the battery forward about 2 inches. But that 800 mAH 3S battery weighs only about 2.25 oz, so it did not have a lot of effect on CG. After installing the aileron servos (as far foreward as practical), adding the wheels and final paint, I will probably be able to nudge the CG forward of the spar to about .5 inch if I add about 1 oz dead weight up front.

I'm also thinking about repositioning the wing. Since it has not been glued in yet, I could open up the wing slot on the fuse and slide the wing aft about 1/2 inch or so. But it depends on how much work it'l take and how much patience I can muster, cause I'm getting eager to maiden this ship!

Sep 09, 2007, 06:18 AM
Wuwu's Avatar

Flight report

Regal can fly litlle fast and very, very slooooooooow!
If motor runs and wing are level - no way to stall.
I'll try to stall - Regal only drop the nose and still flies.
It's very stable and easy to fly basic aerobatic figures!
Landing is easy.
(I'm beginner.)

-Motor (temporary Tower Pro 2408-21 - too much rpm = too much amps) Tower Pro 2410-9Y
-Li-po 3S1P 1200mAh 10C
-Ruder and elevator servo Tower Pro SG90
-Aileron servo Hitec HS-81
-AUW 550g (19,4 oz.)

...Sorry for my poor english
The problem is that I don't know english very well so I could have thousands of things to tell you but I know few words to explain everything is in my mind...
Last edited by Wuwu; Sep 12, 2007 at 05:47 PM.

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