From an R/C plane to a racer !?

[First time Juke]

Re: From an R/C plane to a racer !?

Here is the R/C plane website today I started this thread with:

http://homepage.eircom.net/~skycam/C-17A_Globemaster_III/

It has got paint on it too.




BTW: My finger is pretty ok already...just superficial wounds.

[First time Juke]

Re: From an R/C plane to a racer !?

Tigershark II R/C project goes on:

Today 20:30-21:30 hours I broke the test engine in and top rpms were 14 900 with a 7/4 Master prop. 1/12 scale model weighs 1,5 lbs..so it is very tiny and hard to see in the air, but very soon I will try to get it airborne. I am ecpecting 16 500 -18 000 rpms when 35 % nitro is used in the fuel.

To learn more about 1/12 scale models go to www.rccombat.com there is an airracing section as well. I have flown and build half a dozen of those WW II era fighter models so far.

There is something mystical about the TS 2 racer..it looks really agressive and fast..I just hope all that looks will be turned into speed like the original design goal was. It is not like a Mustang, but it is also not as small as Heston J5 nor Me 209R, but it is a bit smaller than a Tsunami racer was and has moderatly more swept wings, but nothing like a Learstang Vendetta or MA II.

One peculiar thing I have already notised; it has got a lot more wingloading than anything I ever build in that scale before. So a steady hand and good pair of eyes will come handy when this baby flies properly. Landing speeds may be hair rasingly high ( no flaps either ).

Well see ya later,

Juke T / Oulu

[First time Juke]

Re: From an R/C plane to a racer !?

Ok Guys,

I wanted tell the news of the flight attempt of TS II racer.

After I tought that everything was ok, I tried to toss the model in the air ( by myself ) when 12 000 rpms with an 8/6 ( high pitch ) prop was indicated. Result was the fastest snap roll that I have ever seen which ended to lawndart maneuvre....luckily the field was very soft and damage was almost unnotissable ( thanks to the 20 G:s structure ! ). I had no time to even put my hand into the stick to try to recover when the whole episode was over !!!!

Several questions raised and a crew of experienced modellers who were around tried to figure out the problem. It is pretty certain that no further attempt will be made before adequate answers to problem will be found.


I think what the problems were:

There was no opposite aileron trim added before take off toss.

The engine is not pulling to the right at all ( some modellers think a degree to the right is good ).

Someone should have thrown it for me.

Elevator was damaged earlier during the transport and when glueing them again the the left elevator side is pointing half a degree more up than the right one....this results an enhanched twisting motion along with torque that is uncontrollable when plane has practically no airspeed where the ailerons could start to compensate the twist.

Also the plane was trimmed to pull slightly to avoid a dive at the toss start.

Plane may also have CG little bit behind too..that may be a big problem at the time when aeroplane is not fully in an aerodynamical state of flight, but rather an projectile.

Since the plane is like a 1/2 A model it has no rudder control available.

So that was it.

So far I have adjusted more compensating force to the aileron and fixed the little twist in the elevator.

What else should I do to make sure that the vicious " snap roll - lawndart-maneuvre " could be avoided ?

Is it possible that the engine is way too weak for the job...a 14 000 rpm engine could have more pull and bring it faster to the needed speed range where controls start to work again and plane actually flies ?

Grateful of all possible advice.


cheers,

Juke T

[First time Juke]

Re: From an R/C plane to a racer !?

One more thing.

There was also an Eurocup competition for a R/C aircombat and again like last year a guy flying a BEARCAT model based on my plans won...with a large margin...some competitors were from Sweden. 70 % of the models were Ki-61 "Tonys" some Corsairs, Hellcat, Me 109, FW 190 D-9 and Curtis Hawk models were around too and an Il-2 and a Zero. Impressive collisions took place too and in the final two planes lost half of the elevator...one was able to fly a long time with a throttle and aileron control only ! Two engines due to head on collisions are still missing in the " jungle ". That was very exciting when 7 best pilots were in the air at the same time.

adios,

Juke T

PS: I will also make a direction change for the engine on TS II racer model (1 degree to the right ).

[Race5]

Re: From an R/C plane to a racer !?

Juke,
The first thing I would look at if it snapped instantly is CG. That is assuming you got a good throw. I would double check that before making another attempt. I am not a fan of hand launching a ship such as yours either. High HP and wing loading rarely makes for a successful hand toss unless you really know what you are doing. I would go for a bungee launch, either a ramp type or a cart type. The elevators being 1/2 degree off would not make nearly enough difference to induce a roll like that.

[AirDOGGe]

Re: From an R/C plane to a racer !?

I use to hand launch a lot with much success (fields around here were too rough for langing gear). Here's a few things that come to mind, (If you have done a lot of hand launches in the past with other planes, then you probably are already aware of them).

First I'd check the CG, but that's easy to check in the field.
The other item I can think of is not enough airspeed.....Give it a solid toss, like throwing a glider straight ahead. I have my planes trimmed neutral, but I throw it a couple of degrees of up angle relative to the ground. Don't pull up too soon...fly straight and level until airspeed increases enough for better control.

Perhaps you should try yours with an 8/4 or 8/5 prop instead of an 8/6 to bring the rpms up a bit...More nitro will wear the motor faster, burn thru plugs faster and make it idle less reliabily. Remember, fine pitch is best for take-off, while coarse pitch is best for cruise/higher airspeeds once in flight. You might need less pitch for hand-launching.


Last thing that comes to mind is power-to-weight. A friend once had a ready-to-fly electric cessna 28 inch wingspan). It really was too heavy for the stock motor....every attempt resulted in nose-up flight for a few yards and always resulted in a snap to the ground.

---------------------------------------------------

This was one of my favorites. It was originally a Carl Goldberg Ranger 42 (all foam). I split the wing and rebuilt it to remove the dihedral, added full-span ailerons, installed a larger wood elevator in place of the narrow foam one, glassed the bottom to withstand ground abrasion from belly-landings, and popped in an OS FSR .10 ABC motor instead of a .049 (I love the OS FSR motors). A small extension was added to the muffler to reduce the amount of oil that collected on the side every flight.

It flew like a dream, despite the extra weight of the fiberglas, larger engine and 4-channel system (full size servos, not minis). I ran a 7/4 prop to keep RPMS in a decent range and help the hand launches (15% nitro for good throttle range).

(photo taken around 1982)

[First time Juke]

Re: From an R/C plane to a racer !?

Thanks AirDogge and Race5,

I needed some reassurance after that failed attempt. I did change the prop to a smaller pitch. The CG is at 1/3 from the front. Hopefully the plane will advance the field more than 6 yards next time. I will also use less pull for the elevator.

later,

Juke T

[First time Juke]

Re: From an R/C plane to a racer !?

Ok,


I made two more attempts and now advanced 20 yards !

Now I know what the problem is:

When I have to apply opposite aileron the wing looses lift and it comes down since it does not have sufficient airspeed.

For the next flite I will adjust both ailerons 3-4 degree down..this way I'll have some flap effect from the oversize ailerons ( flaperons almost ) and hopefully also able to tune 2000 more rpms from that engine !

Plane is increbibly robust...on 2nd flight it hit the turf at 90 degree bank and I only had to clear the dirt from the spinner and prop, refuel and put the wing back to its place.

0n 3rd flight I managed to straighten the plane before impacting into a rye field...wing attachment dovel was broken, that was all the damage done.

------------

Stay tuned for the next attempt.


later,

Juke T