Project Cox .049 r/c & Citabrian Champion

Beautiful work Mauricio!!…. I’m sure it will do it’s aerobatics in a scale like manner….A nice compliment to the Pitts as well!!

Well, for those who are interested in the Citabria Champion, I'll tell you, today I went to try it and here is my experience:
I couldn't fly it, nor could I get it to really go straight and gain speed, the engine's impact kept pulling it to the left making it impossible to fly, I corrected it from the radio, but it wasn't enough to compensate for the effect. In addition to that, I'm thinking about changing the engine, this Cox .049 with a single transfer doesn't have enough power to be able to pull it with authority, I changed several propellers, but it didn't help much, perhaps if it were a larger model, then the wing surface would take care of lifting at low speed. Nothing to worry about, a couple of tumbles on the ground but at such a low altitude nothing happens, so here I am already evaluating whether to modify the fairing, change the engine incidence significantly and also fit a Tee Dee... I think about it a bit... "I was left wanting to do some flights, but they will come!.... the Chambion Citabria has its fame for reducing the size significantly, well, patience and recalculation... greetings to all

Hi Mauricio, the single bypass [no2] SPI cylinder with a muffler will indeed not be the highest power option. A No1 cylinder without the muffler will do, in my opinion, as will a TeeDee 051, even if tamed by a muffler..

balogh wrote:Hi Mauricio, the single bypass [no2] SPI cylinder with a muffler will indeed not be the highest power option. A No1 cylinder without the muffler will do, in my opinion,  as will a TeeDee 051, even if tamed by a muffler..

Thanks András!!...here is the record of the attempted flight...I'll see how the Tee Dee .051 goes.

Mine don’t always fly first time out either Mauricio…. You are on the right track to give it some more power….. Good you have it on video to help analyze…..Looking forward to Citabria’s next flights

Modifications - Adjustments
Engine change:
The BB .049 engine was replaced by a custom TD .051, "The VIKING"
BB transfer number: 1
TD transfer number: 2 with SPI
BB Glow Plug: standard (low compression)
TD Glow Plug: original (high compression)
Propeller was replaced: MA 6.5 x 3.5 by APC 6 x 3
BB RPM MA 6.5 x 3.5 = 10100 rpm
TD RPM APC 6 x 3 = 14900 / 15000 rpm
Engine degrees:
from 1 degree right to 2 degrees right.
from 2 degrees down to 3 degrees down.
Wheel replacement: (increasing the surface and perimeter of the wheels to try to take off from the ground and have absolute control from the radio control)
from: 11mm (width) x 37mm (diameter)
to: 18mm (width) x 45mm (diameter)
Soon the second flight test...

FYI for more power if needed APC 6x3 + 4,883 rpm



Aug 14, 2019
Cox Queen Bee .074 / APC 6x3 Turbo Plug Test 19,783 rpm

Kamtechnik Turbo Plug Adapter Test
Works with the .074  and Tee Dee / Medallion .09 engines
Static Peak 19,783 rpm  / .214 hp - 158w / 56.2 mph pitch speed
Impressive 23.3 oz thrust!
OS P4 turbo plug / 25% nitro / 20% oil
This is now a viable power house well exceeding the TD .051

End of the Citabria Champion
Well, on the 10th of this month and waiting for the right day, between wind and some rain, I was able to find a space to test the Citabria.
Finally, a powerful Norvel .074 engine and a high-speed APC 7x3 propeller were installed. The engine was able to pull about 660 grams, more than enough to get the Citabria off the ground.
So after several adjustments to the controls, I managed to get the Citabria off the ground (grass runway). It was steady there and I was surprised because the adjustments to the incidents had been perfect, the model was going like a rail, without any tendency and at full speed.
I gained height and began with straight and level flights, turning at the tips and resuming the return circuit, without doing any kind of maneuvers.
Suddenly, it seems to me that the model takes a while to respond to my orders from the radio and suddenly I realize that I no longer have control of the model. It continues on a firm course and without strange movements, a clean flight but without controls, as if the electric current was cut off and it does not resume, engine at full speed, because of the height, I had time to do everything, but it did not respond, the model continued at full speed and finally on that flight line I was waiting for it to crash.
And so it was, the model crashed in front of me without being able to do anything.
I am not sure why:
Maybe my new battery is defective, maybe it loses power for some reason.
Maybe the regulator consumes more than it should.
Maybe a false contact leaves me without energy.
Maybe a loss of extra signal for some reason.
I do not know or at least I am not sure. I did some research on my previous videos and I can see that in the video (Part 5 - minute 11.28 https://www.youtube.com/watch?v=G2qr0mUSRRs&t=438s ) when showing the operation of the engine, at minute 11.28 there is a delay in the radio response, this may be the reason, a premature discharge of the battery, perhaps because it was not in good condition, despite being new.
Conclusion: The model flies or flew very well, perfect, it only needs very little control, especially rudder.
It can fly perfectly with the Tee Dee .051, but this will not make it take off from the ground (if it is grass).
The ideal engine should have a drag of at least 650 grams to take off from the ground (as long as it is grass) and a .074 Norvel or even a .09 Cox may be suitable.
Configuration:
Engine incidence: 1 degree right and 1 degree left.
Stabilizer incidence: 0 degrees.
Wing incidence: 1.2 degrees.
Rudder angle of movement: 10 degrees (both sides)
Stabilizer angle of movement: 6 degrees (both sides)
Aileron angle of movement: 6 degrees (both sides)
Final weight of the model in flying order 520 grams.
Ideal propeller: 7 x 3 APC.
Unfortunately I don't have a video as I didn't have the camera available as the weather was not good and as I said at the beginning of the story, I made some time to take advantage of the weather on that particular day.
Unfortunately I don't have a video, since the weather wasn't good and as I said at the beginning of the story, I made some time to take advantage of the weather on that particular day.

I am very sorry for the accident of your beautiful  Citabrian Champion, Mauricio..I hope the plane can be repaired as it is " only" the wing that looks broken? I had a similar case when radio control was intermittently lost, I realized the power plug of the main switch was loosely sitting in the slot of the radio receiver, but I managed to land with the amount of control that was left active for some short moments, "thanks" to some vibrations making periodic contact for the plug in the slot, (so vibrations this time were useful. )

I appreciate the way you are openly communicating both success and losses in your modeling activities, people tend - understandably- to speak more often about success and stay silent about losses. I must admit I am no exception to that, too.

I trust you will make the Citabrian Champ airworthy soon, your summer flying season is just around the corner  in Argentína! Good luck!

balogh wrote:I am very sorry for the accident of your beautiful  Citabrian Champion, Mauricio..I hope the plane can be repaired as it is " only" the wing that looks broken? I had a similar case when radio control was intermittently lost, I realized the power plug of the main switch was loosely sitting in the slot of the radio receiver, but I managed to land with the amount of control that was left active for some short moments, "thanks" to some vibrations making periodic contact for the plug in the slot, (so vibrations this time were useful. )

I appreciate the way you are openly communicating both success and losses in your modeling activities, people tend - understandably- to speak more often about success and stay silent about losses. I must admit I am no exception to that, too.

I trust you will make the Citabrian Champ airworthy soon, your summer flying season is just around the corner  in Argentína! Good luck!

Friend András, thanks for your message, the model looks relatively healthy, but it was crushed inside, they are made to the weight limit and such a height at full speed, from the frames to the sides they cracked, the monokote that is tense, compresses the whole and getting it to the place, is a crazy job and does not really look good, plus it increases weight... I have a ritual for these cases, it is very personal and with respect to nature, that's it, it now becomes part of the universe. Other projects will come. I feel at peace letting it go. Thanks friend!

I hate to see this , but stuff happens good and bad ! I hope you can find the problem and know what went wrong . A lot of very good work went into the model I do hope you can save it

Sorry for the accident Mauricio….I’ve broken my share as well…. At the same time it is part of what keeps our sport exciting….. When we commit something to the air there is no guarantee that we will get it back in one piece again….. But it makes it all the more satisfying when they are successful…..The crash is only a minor thing compared to all the beautiful models you have presented here on CEF…. We look forward to your next avión

Oh NO what a real bummer a glitch in the matrix no doubt!

Friends, I found the problem!....
The problem is the regulator, although I use them often, it is possible that the components of these new ones that I make do not have the same quality of components as the previous ones.
Soon a test video.

OH No , what a shame , such a beautiful airplane. Very Sorry to see this

Lo siento Mauricio porque tu avión estaba una pérdida toda.
I am sorry Mauricio for your airplane was a total loss.

Voomba

There are basically 3 types of people in our sport.

1. Those who have already crashed

2. Those who will crash tomorrow

4. Those who are crashing right now as I type this........

MauricioB wrote:

It's like solving a murder mystery when you reconstruct the scene of the crime......

MauricioB wrote:Suddenly, it seems to me that the model takes a while to respond to my orders from the radio and suddenly I realize that I no longer have control of the model. It continues on a firm course and without strange movements, a clean flight but without controls, as if the electric current was cut off and it does not resume, engine at full speed, because of the height, I had time to do everything, but it did not respond, the model continued at full speed and finally on that flight line I was waiting for it to crash.

And so it was, the model crashed in front of me without being able to do anything. I am not sure why: [...]

Creo que el problema fue causado por otro piloto de sombra, cerca de ti.
I think the problem was caused by another shadow pilot near you.


-¿De verdad? - No, ¡es broma!
Really? Just kidding!

¡Dios le bendiga todo!
God bless you!

Well looks like you have found the problem , I notice a few people are using these regulators WHY ? I never had to do this with the NiCads I was using .