RE: Lomcevak how to??
 

Very good deffinitionn Dan,
I didn't know there were that many variations of it. So in a since, we are all pretty much correct. I also have heard of it being call Headache. Thanks alot Dan for shedding more light on the subject. BTW- I like the Christen Eagle Pitts. I have 1/3 scale S2..[:o]all I can afford...
The closest thing I can afford to a full scale is my Rally 2B Ultralight.

Shane

RE: Lomcevak how to??
 

Let's roll... thanks for that. From what you are saying, which is what I assumed before I posted, is that there should be a diff between left and right entry due to prop rotation. Makes sense they are starting left as that is the direction that will maximize gyroscopic precession effects. Snaps are always more violent to the left, etc. Also makes sense you need to be wide open to maximize the gyroscopic effect. Thanks for the info.

Shane. I posted a link to a description of the five general Lomcavaks back a few posts if you are interested in reading details, but it looks like LetsRoll copied that doc in the last post, so there might not be much more info at the link. The headache is supposedly the loosely translated English meaning of lomcevak. I think more precisely, the def is "headache caused by too much drinking", but since I don't know Czech, I couldn't say for sure. There is a lot of lore on Lomcevaks and it is sometimes hard to sort the BS from fact, but this is my understanding of how this all started.

Checz pilots were flying Russian YAK 18s. (This is why sometimes you here it is a Czech maneuver other times Russian. It is really a Czech pilot flying a Russian plane.) Apparently they were bored, and decided to tumble these planes and had great fun doing it. First pilot to try became disoriented in the tumble, or cracked his head on the dash, depending upon who you believe... hence the name lomcevak (headache.) Only problem with the tumbles was the gyroscopic forces were so large on the planes that cranks were being bent and in one case the engine was nearly ripped from the plane. Early planes (engines and mounts in particular) were not designed for the forces they were applying. In all, four YAK 18s were seriously damaged before the Russians told the Czech pilots to cut it out or else.

I guess from all this what I conclude is that for the best chance of getting a lomcevak done in a model, you need to be wide open and you should perform the maneuver to the left, i.e. exactly as LetsRoll described a few posts ago.

Cheers!

RE: Lomcevak how to??
 

Shane,

Glad to hear you have a biplane. The Christen Eagle you see in the picture is a 1991 model that was built out in Redding, California. My cousin, Chuck Porter is the owner, and we keep the airplane in Dayton, TN at Mark Anton airport. I have been lucky enough to help with maintenance since I was 14, and over time have learned a lot about them. Now he makes me do all the work (if you would call it that...)! Ha! But I figure that having my name on the side of the canopy and getting to fly it is an awesome trade...

Until next time,

Dan Payne
Chattanooga, TN

P.S. The guy next to the airplane in the one picture is Chuck, my cousin. He is an ex-F-86 Sabre, F-100 Super Sabre pilot and retired United 737 captain.

RE: Lomcevak how to??
 

John,

Glad to be of help. Let me know if I can help you out with anything else.

See ya,

Dan Payne

RE: Lomcevak how to??
 

Dan,

Here is my Pitts... I am a proud pa pa!!! It looks awesome comming down the runway a foot of the deck wide open inverted:D:D A friend just buaght the 1/3 scale C- Eagle...NICE!
Later,
Shane

RE: Lomcevak how to??
 

Shane, Awesome Pitts,

It looks like you guys also have a nice fleet of models on the field as well...

See ya,

Dan

CONIC LOMCEVAKS
 

As you all know, the IAC doesn't have the Lomcevak in thier Aresti book because of the factor that it is a gyroscopic manuever. Just wanted to make it clear to everyone that a gyroscopic manuever cannot be judged in competition. The only place you will see this done in a contest is in a 4-minute freestyle where the judging is basically about who's routine looks the most cool.

We all know the 45 upline, quarter roll to the left, left forward stick and right rudder, neutralize ailerons when it breaks Lomcevak. Right?

Ok, now I am gonna give you a manuever that will really make you smile. It is called a conic lomcevak. During this manuever the airplane is actually flying upside down and backwards! Here's how it works.

Pitch the airplane up to about 80-85 degrees. Slightly before vertical

Hard left aileron, Hard right rudder.

As soon as the "wallowed" roll starts to come around to vertical go hard foward on the stick.

When you go forward on the stick, try it both with and without the left aileron and see which gives your model the best results.

Power setting is full the entire manuever.

The airplane will fly upside down and backwards at one point during the tumble.

See Ya,

Dan Payne
Chattanooga, TN

RE: CONIC LOMCEVAKS
 

Lets Roll,

Hey that is EXACTLY what I see when I do what I mentioned when I started this thread! Remember the reverse "J" stick inputs I mentioned? The plane actually flys upside down and BACKWARDS for a short period, sometime its slides backwards(Maybe a horizontal line of about 20'.), sometimes it tumbles depending on the timing of the Aileron inputs. looks real cool whatever you call it. :D

I knew I wasnt imagining it.

RE: CONIC LOMCEVAKS
 

John Willman,
Off Topic if I may, I was look at Carden's site the other day and saw your plane on it. Looks Sweet with the bigger pics. Avitar doesn't do it any justice. I have several freinds that own Carden's and they love em'....
Shane

RE: CONIC LOMCEVAKS
 

It is about time for a Czech to step in... and clarify few things. Lomcovak really does not mean anything in "proper" Czech, it is a colloquial term that can be understood as "one that shakes you violently", coming from the word "lomcovat" (=to shake violently). Can be used for anything that shakes you, like a shot of a very strong brandy or even a cup of strong coffee.

As for the story about Yak-18's, I never heard this one before. From what I know, the maneuver was invented by Czech pilots on Czech airplanes, between world wars.

David

RE: CONIC LOMCEVAKS
 

JohnWillman wrote:
David Kyjovsky:
Hats of to the Czech for inventing the lomcovak (and for changing the way aerobatics is performed today).

As far as I know the lomcovak was first displayed in public by a Czech (Ladislav Bezak), flying a genuinely Czech aircraft (the Zlin 226) at an airshow in Brno (Czech city) in 1958.
At the first World Aerobatics Championships in 1960, the Czechs made a bold move towards dynamic high-g sequences rather than graceful rolls and loops, which were, until the beginning of the sixties, accepted aerobatic style.

The Czech had no need for Yak aerobatic aircrafts since they had their own native aircraft industry (Zlinska Letecka Akciova Spolecnost or Zlin for short) that produced some of the best (IMHO, THE best) aerobatic aircraft in the world of that period (Zlin 226, Zlin 326 and the fabulous Zlin 526). Nowadays they have been surpassed by high performance aircraft (Sukhoi, CAP and EXTRA)

An interesting side note: Today most aircraft use symmetrical airfoils but it hasn't always been like this. I had the opportunity to inspect a full-size Zlin 526 some time ago and to my astonishment I found that the airfoil at the wing tips are markedly undercambered as you would expect in a vintage glider. I also found out that the Bücker Jungmeister used a Clark-Y airfoil.

/Red B.

RE: CONIC LOMCEVAKS
 

Well.. I have the CERMARK SUKHOI ARF. 68" wing. 10 pounds dry. OS 1.60. When I try to do a (PSEUDO) LOM with this plane, It gets tumbling ass over tea cup. It will continue all the way to the ground, spinning about an axis about at the main spar of the wing. It does this at about 1 complete revolution per 2/3 of a second. After several turns, I can often neutralize the controls, as long as I keep the power up, it will continue... at least for several tumbles. It kinda looks like a knife edge spin. Only the wing is nearly horizontal. I venture to say, based on the fact that leaving the power on will continue the maneuver is good evidence that there is some gyroscopic precession going on. I have had planes with modest sized control surfaces that would flat spin to the left, but as soon as power was applied in an attempted right hand flat spin, it would only spin faster. To the left, the precession would clearly pull the nose up.

RE: Lomcevak how to??
 

I had a Hobby Shack Lucky Stik, made before model tech bought Hobby Shack out, that would Lomcevak. At the time I didn't know that was the name of the maneuver, but after seeing the video at the link above I realized it. The way I entered the maneuver was to climb straight up at full throttle and throw a right, upright snap roll and hold it. The plane would eventually stall and flip end over end like the plane in the video. It would do it every time. Ever since I quit flying it I've been trying to get another that would do the same thing, but none have...come to think of it, I've never had another plane that flew as well as that one did, and my stable includes a Great Planes Ultimate Bipe, a Hangar 9 Ultra Stick 40, and a Hangar 9 Funtana.

RE: Lomcevak how to??
 

I'm glad that this maneuver was finaly properly explained without much sweat. Now, I just had a thought. Hypotheticaly if you had some sort of weight at the tips of the prop on your model, wouldn't you thus increase gyroscopic force on your model ? Maybe you could perform a real "lomcovak" with your model.
Ps: By the way that is the proper spelling of it.

RE: Lomcevak how to??
 

I realize this is a nearly 10 year old post, but I just wanted to point out the fact that a Lomcevak IS possible with a 3D ELECTRIC airplane with an OUTRUNNER motor of "significant" diameter. In other words, my Carbon Z Yak can perform the maneauver correctly just like full scale. The big metal can that spins provides enough gyroscopic force that you can actually pretty much sustain a lomchevak all the way to the ground. lol

RE: Lomcevak how to??
 

they can be done with a foamy too, good CG and huge surfaces with extreme deflections