Twisted Hobbys Crack Yak! - RC Groups
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Jan 04, 2012, 11:52 AM
Team Extreme! Team Twisted!
hercdriver7777's Avatar

Twisted Hobbys Crack Yak!

OK guys, as with all my build threads I will put all the info in the first post here and keep it updated.

I know you guys are looking for pics and vid at this point but the fact is we don't have them for you yet. We have 3 view drawings that Twisted is reluctant to put out in the world until the production is on the water. We've got some pics of prototypes that will come out as soon as we've got a real printed production plane to go with them. However, I can give you lots of detail about the design and how we made it.

So the Crack Yak was designed to fit a very specific purpose. In the Twisted lineup of small inexpensive profile foamies we have a lot of stuff that is designed for learning 3D flying. We have a lot of demand for these smaller planes and have gone to great lengths to have a full offering of them. Here's a bit of history leading up to where we are now:

-We've got the Vector, which is very floaty and was designed from the beginning to be a 3D trainer for the most basic of 3D maneuvers like hovering and very slow flying harriers and so forth.

-We've got the Xtra Slick which, is designed as a step up in capability from the Vector. It is great for learning slightly more advanced maneuvers like continuous rolling, knife edge, walls, waterfalls snaps etc... The Slick has been very popular and a great addition to any fleet. For a long time my learning curve for new maneuvers went like this: Sim, Slick, Telink and then Balsa.

-We have the Crazy 88 in there for bipe lovers and to add some spice. That plane will do just about anything and if you are into bipes it is a great plane for learning the ins and outs of what makes bipes a little different to fly.

-Enter RC Factory. Prior to RCF joining up with Twisted all of the small foamies were made in house by Brad by hand. They were also painted in house by Brad and his helpers like Dan. With RCF now on board we have access to their expertise in EPP construction methods, a source for quality EPP foam and top of the line production and printing. The major benefit being that now Twisted is left more time to spend on designing and customer support. It also means we can now get enough kits to meet demand.

-Enter the new power combo. The new motors we have now are way more efficient, reliable, powerful and they come with connectors all ready to go. A major improvement to the lineup across the board!

-With RCF/Twisted we now have the new Edge and Sbach. They are great designs with excellent production and construction details. They are kind of taking over for the current Xtra Slick. They are stiffer, better built and in several ways just an improvement to fit into our bread and butter 3D plane slot.

That kind of brings us up to speed on where we are now. Some time after the Slick first came out Brad and I decided we needed a small EPP profile to add to this lineup that was more advanced than the Slick. We wanted something that had a slightly higher wing loading than the others. We wanted a plane that was stiffer and had a faster roll rate. One that would be more capable and fly more similar to balsa but yet still offer some of the characteristics that would make it a good learning tool for people progressing up the learning curve. We wanted an Xtreme Aerobatics plane that was not just 3D, something a little more precise. The Crack Yak is the end result of a long line of prototypes designed to fit those criteria.

The very first prototype was supposed to be a pattern type plane and Yak was no where in the thought process when I designed it. We tried several different construction techniques to get the most rigid plane that we could. We ended up with a construction technique similar to what is on the RC Factory Clik but it had a laminated EPP wing with three layes a different thickness EPP. Keep in mind this was well before the two companies came together.

The main thing we learned from this first prototype was about SFGs, turbulators, leading edge slots and other aero devices that might help in our design goal. We experimented with everything from canards to spades to vortex generators trying to find out what really works with small EPP stuff and flat plate wings. From these tests we came upon the leading edge design, SFG shape and locations and aileron counterbalance design that would eventually end up in the Crack Yak. We also figured out the right dimensions and geometry of a plane that would yield the flight characteristics that Brad and I both agreed would be what we were looking for.

The end result at the time ended up being too complicated and expensive to kit given Twisted's in-house production capability. About the same time the Telink stuff showed up and we left the project unfinished.

Then Brad got the bug to do a Yak and asked me if I wanted to do it. He loved the old Yak 55 that started this whole small EPP profile segment and wanted to do something similar. I felt that the Yak was over done and that if I saw another model of a Yak 55 I might just poke my own eyes out. The end result of that discussion was that we would look into doing a Yak but that it would be a Yak done how I envisioned a Yak should be.

So, I started working on this thing one night, trying to look at what makes a Yak a Yak and what were the good parts of it. Then I looked at the old pattern plane proto three view drawing that I made and kind of superimposed the Yak three view drawing on top of it and there it was, the most badass looking little Yak there could possibly be. I mean, it looked like a cross between a fighter jet, a supermodel and a Yak 55SP

After I drew it up I sent a copy to Brad and he said, "Holly #$%^, that's different"! He said, "I thought we were doing a Yak, you must be on Crack or something".

We tossed some ideas back and forth and before you could find a tube of Welder's at Lowes I had the first prototype built and flying.

Prototype 1. Too heavy. The construction techniques we used on the pattern plane with laminated EPP wings was too heavy. However, I could tell from this first plane that it had a lot of potential. It flew like I wanted a foamy to fly but needed much more work before we could sell them to the public.

Prototype 2. Too flimsy. We could not get the higher quality EPP in from our supplier anymore and it was making this project tough. I was getting more excited by how this plane was flying. The roll rate was fast! The stalls were clean like and Edge but it would snap and spin like an Extra.

Prototype 3. Wasn't happy with the elevator response. Changed elevator design, moved the stab forward and changed the servo location. This kind of brought the whole flight envelope into focus. I could now see that we had a plane that would out perform the rest of the fleet. It was a joy to fly!

Prototype 3. Coupling. Moving the stab forward changed the coupling and I needed to redesign the fuselage and rudder shape. I was very happy with the design by this point. The rudder response was so perfect now that you could just jam the stick in either direction and it would turn flat all by itself all day long. I have never flown a plane that had so little coupling all the way from small throw to huge throw. If I could get it just a little bit stiffer I would be happy to go to production.

Prototype 4, 5. I got tired of messing with it and my buddy Ken built two of them. We could not get it stiff enough to perform like we wanted partly because we could not get the right density or quality foam.

Prototype 6. I sent Brad the templates and he built one to verify what I was telling about this plane flying awesome. Brad flew it a lot! Then he kept flying it and then couldn't stop flying it! That's all he flies now. He loved it and agreed we were onto something special that people would really like. It's addictive like ______!

So now it was in Brad's hands. He needed to find us the right quality foam and build the jigs and everything to make the plane. Then, RCF came along and the Edge was born. That plane was so stiff and so well built that we both immediately saw that having RCF build the Crack Yak was the missing ingredient to make this plane absolutely phenomenal. Brad sent the drawings to RCF and they very quickly sent us a couple more prototypes.

Prototype 7. Perfect!! I love the work RCF did on the production and oh my god does it fly well. It is such a pleasure to fly and so capable for a little foamy that everyone who I have let fly it has asked to be on the list to get one of the first ones.

Prototype 8. Dan built this one which is exactly the same as mine but Dan tested out the paint scheme to see if it works as well in real life as it did on the computer. It does and WOW does it look cool! This thing should have guns on it!

We made a couple of very minor suggestions on production details and now it is in the hands of RCF to churn out the kits. My understanding is that we should be seeing it soon (Feb maybe). My only request was that we could get them in everyone's hands early enough that people could have them built and ready for SEFF.

Key design features:

Size. It is a little pocket rocket. 32" wingspan. Fly it anywhere and in any space or wind condition. Generally I like the bigger is better idea but in this case we tried several sizes and people who have flown them like the smaller size best. Even in high winds, people liked the smaller version.

Roll rate. This thing rolls fast. If you have flown an Extreme Flight EXP or 3DHS Slick you will experience a similar roll rate here. So many of our smaller foamies have been slow rollers and that's fine for learning the maneuver but with this plane you can now wind it up and go crazy like a depron indoor foamy. Rolling 8s and loops are a blur!

Leading edge. The leading edge on this plane is notched to provide a clean stall break on elevator type maneuvers but also to give less wing area at the tips so that it will snap, turn and roll better. So, unlike a double taper wing that may tip stall to one direction or the other dramatically in a stall this one will stall relatively straight. It gives better harrier performance than a fully tapered wing but still retains some of the advantages of the taper. The notch also seems to act like a little vortex generator which also helps with slow speed rolls and turbulence going over the stab.

Elevator and rudder control. The tail length, position and design of the tail control surfaces make this plane a little more whippier (if that's a word) than the Xtra Slick for example. You can toss it around with the elevator with tight waterfalls and tumbles. The rudder will turn it around so fast that you can do knife edge loops in your trailer.

We are really exited to get this plane out to you guys. All of us have put a lot of work into it and are so happy with it that it is going to be a pleasure for us to see you all enjoying them! Happy flying!

Other than that you guys are just going to have to wait until we get some production kits to get out..
Last edited by hercdriver7777; Jan 20, 2012 at 03:22 PM. Reason: More Pics
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Jan 04, 2012, 11:55 AM
3D Hack
JC Spohr's Avatar

Jan 04, 2012, 12:29 PM
Registered User
Me 2
Jan 04, 2012, 12:40 PM
Registered User
livinma1's Avatar
I am here
Jan 04, 2012, 12:44 PM
Barefoot Birkinsomething
rcbirk21's Avatar
cant wait to see it herc
Jan 04, 2012, 12:54 PM
Justin S
justinsebastian's Avatar
Alright, here I am...where's my crack yak?
Jan 04, 2012, 05:05 PM
Registered User
Are you home yet?
Jan 04, 2012, 05:09 PM
Justin S
justinsebastian's Avatar
If I hadn't seen one in person, I'd think it were a mythical creature
Jan 04, 2012, 05:16 PM
Twisted Realm's Avatar
You guys are to much.
Jan 04, 2012, 06:06 PM
Don't give in to gravity
Gravitycheat's Avatar
Jan 04, 2012, 06:39 PM
Registered User
Well...if it's half as good as described it still sounds like a winner...I'm in for one as soon as it's available...perfect size for the small field I fly at and if it handles wind I'll be set. Have actually been unable to decide which of the twisted planes to buy, gonna wait for this one, I like the "new design " factor

waiting impatiently already
Jan 04, 2012, 06:48 PM
Registered User
out of curiousity....Are you flying this on 2 or 3 cells ( assuming 2 cell 450's )
Jan 04, 2012, 06:49 PM
Team Extreme! Team Twisted!
hercdriver7777's Avatar
2S 450. The new power system has 3S type power though even though it is on 2S.
Jan 04, 2012, 06:50 PM
3D Hack
JC Spohr's Avatar
Originally Posted by Twisted Realm
You guys are to much.
So let's really go over the top...

I've wanted one since I first learned about the project. I still want one and I want to be in on the first production release. Therefore, after Chris, Brad, Dan and their very close helpers get theirs, I want to be #1 on the list.

So here's the list of people who are commited to production run #1:

1. JC Spohr
2. <your name goes here>
3. <more names here>
4. <and here>
5. ....

There you have it Brad and Chris, your first sale.

Feel free to collect names and add the list to the first post or wherever you'd like to track it.



ps - Supersize me - make it a combo!
Jan 04, 2012, 06:50 PM
Registered User
corsair214's Avatar


cool i will take the chick in above pic and ya 'all can have the yak

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