Composite Arf or Krill?????????

[The_Wreck]

	Quote: Originally Posted by pepatrick
	One of the Johns from J&J tail wheels has just finished building a 3.0 Yak and Krill Yak for the himself and the other John from J&J...He will probably have some good comments about the two as well...

Phillip is right, we completed the Comp-Arf 3.0 Yak about 4 weeks ago and just got to maiden it last weekend.

For info on building the Krill Katana (which is similar to the Yak), you can't get much better than Joe's thread at:
http://www.flyinggiants.com/forums/f...tana-39-a.html

Build Comparison

Concerning the build, there is substantially less work to do in putting together the Comp-Arf than the Krill, but neither are bad if you have a fair amount of building experience. Phillip listed a lot of them above, but to me there are some good and bad things I think need to be pointed out:

Comp-Arf:

• Aileron Servos are a pain to install and I am just not crazy about the method they use to install them. The outboard servos are just ridiculous. We ended up creating an allen tool out of a 3 foot long dowl to get them installed. Making a quick change at the field a much more difficult task.
• Also concerning the ailerons servos. They are mounted in the center of the wing depth wise. This means that in order to get good throw on the ailerons you must use 2" arms on the servos which is really longer than you need and you give up a lot of mechanical advantage, or you have to hack the wing up to allow the ball link and linkage to clear the skin of the wing. You can see this on several of the build threads for this plane. This could easily be cured if the servos were mounted closer to the bottom skin of the plane.
• The wings will Chew up the fuselage during flight, so putting some type of clear vinyl on the fuselage is a must to protect it.
• Have to glue canopy to Hatch, which is easy to screw up. (This can be done with care, time, and patience, of which I have little, but I do have good friends with plenty of it)
• The control arms are installed at the factory (which is good), but they are not square with the hinge line so they tilt and move to the side as the control surface moves back and forth. This is not a huge problem with ball links, but could easily be fixed at the factory.
• The cowl vents are junk and everybody I know has them break in half on a regular basis, Wayne I believe has solved the problem using silicone to absorb some of the vibration, check his build thread listed below. On John's plane we chose not to put the one's on the top of the cowl since they are not functional anyway.
• I really like the short cowl ring on the Comp-Arf.
• The supplied hardware is nice, but we switched most of it to STD dubro 4-40 and titanium pro-links.
• Tank Tray is nice and goes right on the Wing Tube.
• I like the wing tube compared to the Spar setup on the Krill. Wish it was Carbon Fiber....Composite-Arf just seems logical and a CF one is about 1/2 lb lighter.
• Landing gear is kind of heavy, but it is really strong. However, this means it has no give and even the best pilots get hops on landings sometimes.
• The hole to mount the stabs is pre-drilled with a metal grommet in the stab. Super nice and an area that has caused problems for me in the past.

Krill 37% Yak

Some Pictures of my build can be found at:
http://www.flyinggiants.com/forums/f...sembly-19.html

The major difference is the weight difference. The Krill feels dramatically lighter and more fragile than the comp-arf. The skin is thinner and the formers in the fuselage and ribs in the wings are some type of laminated Foam. The skin of the comp-arf is strong enough that it does not have nearly as many formers or ribs. I am sure the wings are really strong on the Krill see the picture below of Ivo Krill sitting on a Katana wing.

• Hard to complain about things the factory should have done differently, because they do not do that much for you.
• The Aileron servos are attached to wood blocks glued to the hatch in the wing. I have had numerous problems with this setup in the past. The blocks come unglued or break. IMHO this setup sucks. However, The hatches are boxed and very strong so it is a simple conversion to surface mount the servos. Which is my preferred mounting method anyway. It is comforting to be able to see the servo and makes for easy changes in the field. See this post: http://www.flyinggiants.com/forums/470904-post224.html
• The cowl is large but it is easy to convert an internal mount which cleans up the outside appearance of the plane: http://www.flyinggiants.com/forums/470898-post222.html
• The paint lines on my cowl did not quite match up.
• All the surfaces must be cut out so the control horns can be glued in. Not a terrible job, but one that requires some patience and measuring. At least you can ensure they are square with the hinge line.
• You must check and maybe set the incidence, some people had theirs spot on from the factory, I had to adjust mine slightly, I hope I got it right, time will tell when it flies. If it is off some this is not a huge issue, just adjust the incidence and glue another biscuit to the inside of the fuse.
• Motor Dome must be mounted to the firewall, Easy to do, and it makes other parts of the build a lot easier, because it makes it easy to access the inside of the plane from the front.
• Must drill blind into the stab tubes through the wing and secure with screws. Some people can do this in their sleep (Joe), I feel like Ray Charles when doing it and seem to bat about 75% on hitting the tube dead center.
• Like Phillip said the canopy is fantastic and pre-painted. However, I wish that it had a little more Hatch associated with it. This makes reaching the forward wing bolts a lot easier if part of the top front part of the plane came off.
• Tank tray must be fabricated. See the pictures at the thread above. We chose to hang it from the top to make access to the wing bolts a little easier for my large and muscular arms.
• Landing gear is light and is really strong. Comes with nice light foam ball bearing wheels.
• Comes with wheel pants but I prefer the Spats on the Comp-Arf. I am not going to use them.
• If you want a can tunnel you must build it.
• Tailwheel is very heavy and the tire is not very durable. Fortunately I can solve that problem myself: www.jjtailwheels.com

Flying Comp-Arf 3.0M Yak

It flies really well, snaps are crisp and straight, flies at really constant speed, great down lines, rolls great. Mixing is minimal and it floats around even at 40+ pounds. If IMAC is your thing I do not think you can go wrong with this plane, but a DA150 on Cans is getting pushed to its limits with this plane at this weight. It manages OK with a 2-bladed prop, but struggles with a 3-Blade. See Wayne Matthews build thread, he is an IMAC extraordinaire, and flies with us at GMA. He just switched to a DA170 and is extremely pleased with it. http://www.flyinggiants.com/forums/f...5sp-build.html

I believe to get the Comp-Arf to really shine 3D you may need to set the balance a little bit further aft than most would like especially if IMAC is your game. I experienced a fair amount of wing Rock on Phillip's plane when doing an upright harrier, and his balance was set where it took some down elevator to hold an inverted 45 degree upline. I am not saying that there is not a balance "sweet spot" to be found, because I have not have enough flights to really experiment with the balance. I typically like my planes to require a little down elevator for level inverted flight, and to hold an inverted 45 upline.

I think for 3D the biggest obstacle for me on the Comp-Arf would be the power, there is no substitute for good acceleration when playing around close to the ground. On a 150 and cans and a 32-10 2-blade the Comp-Arf reminds me of my old TOC1 17.5lb 50cc Yak with a DA-50 and pitts muffler. It hovers around half-throttle and pulls out reasonably strong. Nothing like a 27-28lb 35% plane on a DA-100, My Dalton would rocket out of a hover compared to the old TOC1 and this Comp-Arf. I have yet to see this plane fly on a 2-Blade with a DA-170 and Cans.

I have no experience with this plane and a 150 on pipes, but they could totally change my opinion if the power is a lot better.

I can tell you if 3D is your thing then there needs to be some mods in my opinion to the Comp-Arf. You will need to modify the elevators and ailerons to get more throw. The Ailerons can be done pretty easy by sanding the gap, and the elevators require some judicious use of the dremel on the holes that the phenolic mounting horns go into. Look up some of Mark Trent's stuff, he is the best resource I know of for making the Comp-Arf planes more 3D capable.

Flying the Krill

Not much I can add for now since I have not flown it. However, I can make some observations. You can get great 3D throws without any problems right out of the crate with 1.5" servo arms. The plane will be between 4-5 lbs lighter than the Comp-Arf, so it should have excellent pull out with a 150 on cans with a 2 or 3 blade. And be ballistic on a 170 (As Wayne said when revving his 170 at the field "Yeah Baby!!" He likes to rub it in that he already has a 170)

The wing thickness is 3" compared to 4+" for the CA. This should make for good IMAC flying and based on my experience better 3D flying. The wings should stall easier and be more stable in a high-alpha attitude.

Hope this post was informative and not too long.

John

[andywynn]

Thanks PePatrick and John, what more could i ask for. Very detailed and informative. I still have reservations about the looks of the Yak. I think its going to be a case of heads or tails!!!!!!!

[pepatrick]

When I first saw the plane..My impression was less than enthusiastic...I saw it (the very plane I purchased) at Joe Nall..and even then it did not get me too excited..I was to busy looking a Composite-Arf Extra 260 that I was druling over. It was Ray Labonte's plane..a 2 year old Comp-Arf that looked like it was just built yesterday...This guy does it right..anyway..before I get too far off track..I saw the Krill fly..It looked much better in the air than on the ground..and I started to do a little research on it..the ugly looks started to grow on me..(see my above post..yeah the ..hot bodied ugly chick)..To make what is becoming a long story short...I went to look at a used Extra 260 in S.C...the guy had the Krill (from the Nall) there..and I jokingly asked if it was for sale...At first..it was not..but by the time I left there it was..so now its mine..And they guy I bought it from..bought another one (different scheme)..so he was pretty impressed with it..

[bpetty620]

This is true i did like the yak enough that i bought another one. My new yak should be ready in about two weeks, i have flown both the katana and krill yak, for me the yak is a better IMAC plane than that of the katana, reason being less wing area. the katana flies just as good but in snap's the yak is cleaner, the katana seems to barrel roll throw a snap even with a lot of ailron. the yak has a long tail that help's too, but for the most part i just like the looks of the yak over the katana


Bradley

[pepatrick]

Bradley..You will probably have yours done before mine...I am still waiting for the DA-170...I hate waiting for toys.

[Pittsflyboy]

Subscribed

[guus]

I am also looking for a composite plane and I find the best advantage about composite-arf that you can buy spare plane parts (wings stabilizer etc) in case of a crash.
the plane don't have to be that big but the extra 2.1 has not so stunning paint job so the extra 2.3 is at pole position and the krill katana 28% at second.
But still looking going to buy after the winter (still saving the money to buy)

[nickb]

You can buy spare parts for the Krill's rom Phil at Skyline.

[guus]

	Quote: Originally Posted by nickb
	You can buy spare parts for the Krill's rom Phil at Skyline.

OK what is the site ?????

[nickb]

http://www.skylineaviationonline.com/

[mrs66]

i would not go another krill after my experiance the krill look great fly great but if something wrong dont ecpect any support i would go comp arf at least they listen to u

heres my story sorry but http://www.flyinggiants.com/forums/f...rill-wing.html