RE: Nitro Planes Bobcat
 

Yes a small amount, if I recall correctly about 4%-6%.

RE: Nitro Planes Bobcat
 

The mix makes the elevator go up or go down when the flaperons are deployed?

RE: Nitro Planes Bobcat
 

Hi again OpJose,

I just wanted to double check with you where should the ailerons and rudder travel should be measured (according to the instructions travel), on the widest or on the narrowest part of each control surface?

Also, as per your previous comments, I know that the elevator central position should be measured on top of the stabilizer instead of the bottom, but what about the aileron central position? should I make the ailerons level with the lower or the upper part of the wing?

Finally, this is my first pusher airplane, how much should I enrich the mixture of my OS 55AX so it won't overheat?

Any other flying tips you could give me?

Thanks.

RE: Nitro Planes Bobcat
 

Hi Opjose

Do you find your GMS .76 to be over powered at all. I'm thinking of puting an os 75 ax on but i'm worried of being overpowered.
Also, do you program up or down elevator to be mixed with spoilerons

Thanks

12zw

RE: Nitro Planes Bobcat
 

Apologies for reviving such an old thread, but I just got this plane and would like some help. opjose please reply;)

I just test flew this plane and it did get off the ground without too much effort. I have a 46size electric motor mounted on the back with a 13x6.5 prop on a 5S pack. I have the motor pointing up a bit so I'm assuming after reading this thread that this helps it get off the ground. I took off knowing the plane was a bit nose heavy.

When in straight line flight, I noticed the elevator had enough throw to get the nose pointing up/down, BUT it only comes back up after having to pull back on the elevator about 3/4 down. It will keep pointing down with no movement until I reach that 3/4 point. I know the nose is heavy but I never experienced this before. It's almost like the nose does not want to come back up, but when it eventually does, it comes up quick!

My question here is, should I lift my ailerons up a few degrees to fix this? I will ensure its balaned properly on the next flight, but does this model require this "up" aileron to help up elevator controls? Does this plane experience difficulty in raising it's nose when pointed down?

Or do u suspect I'm seriously just nose heavy?


Please help me find/confirm my fix.

Also, should I add this up degrees on my ailerons to fix this problem, Will this "spolieron" I'm reading about not affect my takeoff. Ie. Will I not go vertical now on takeoff?

Im also glad I read this forum. I set my flaps to go down on landings.. This would not work on this plane? Correct? I should make them go up 1/4 inch to get the nose up on landings?

For the record, first landing bent my 4mm retract legs badly. The landing was hard. I put in some some spring dampened oleos now, but there's still alot of work to be done to fix them nicely. I still find it amazing how much thinking and work can go into getting the landing gears to function correctly... It's been two weeks now and still working on every kink in my retract system..

Thanks for any replys...

RE: Nitro Planes Bobcat
 

The mix makes the elevator go UP slightly to compensate for the slight loss of lift caused by the spoilerons ( reversed flaps ).

RE: Nitro Planes Bobcat
 

I'm not sure I understand you.

The motor does not need any additional up thrust ( rear or prop side of motor pointing a bit up ), it should be level with the mounting blocks/surface.


I assume by "down" you are talking about STICK movement on your TX not elevator movement on the plane.

If so, have you set the elevator so that the trailing edge of the control surface is LEVEL with the top part of the forward part of the elevator?

This should give you just a bit of upward deflection of the elevator when the TX is at stick center.

This plane needs a bit of speed for the surfaces to be effective too so flying to slow will make it mush around a bit like what you are describing.

I don't understand what you are saying... you say "it will keep pointing down with no movement".... what "points down"? The plane in flight ( it goes into a dive? )???

Check your linkages and surfaces it also could be that the servos are not moving the elevator up when the plane is in flight due to blowback forces.

Push a bit on the elevator as you move the stick back to raise the elevator... make sure the elevator comes up smoothly in spite of the slight force against it.

No raising the ailerons kills lift, which we want for landings... but not for normal flight.

Your ailerons should be level at stick center.


No it reacts much like any other jet... it will not raise it's nose if it is going too slow, but at speed it reacts to stick inputs just fine.

Double check that C.G. ( with the tank EMPTY! ).

With the elevator set with the slight upward deflection as I mentioned before, the plane will fly hands off WITHOUT dropping the nose, at 50-70% throttle using the engine you have on it.

With a larger engine it takes even less throttle to keep it flying level.

Absolutely NOT!

The spoileron's are to help shorten landings and roll-out.

They kill lift, so that you can bring the plane in nose high, like a real jet, and keep the nose high after the main gear touch down.

The longer you can keep the front wheel off the ground the faster the plane stops.

No, spoilerons are turned OFF for takeoff.

Flaperons ( dropping both ailerons ) is a BAD idea for this plane.

Because of it's swept back wings, flaps will make the plane less stable at low speeds and make it mush even more just after take off.

Don't use them!

Landings should be very smooth with this plane, but you must maintain throttle and airspeed.

Your "dropping nose" symptom may be working against you at landings.

Once you correct that, landings will be easier...

DO NOT attempt to use spoilerons until you have the nose drop problem sorted out, as spoilerons will only make a bad situation worst.

RE: Nitro Planes Bobcat
 

Thanks opjose!!!

I really appreciate you taking the time to answer some of my questions!

Much appreciated! will let you know how the next flight goes..

Regards

RE: Nitro Planes Bobcat
 

BTW: I should have clarified.

Normally pusher plane C.G. is affected adversely with a FULL tank.

In other words filling the tank moves the C.G. BACKWARD ( bad ), while in a regular tractor plane a full tank moves the C.G. FORWARD ( good! ).

The C.G. for this plane is given with an EMPTY tank, but in reality it should also be checked with a full tank to make sure the C.G. doesn't move TOO far back in this state.

Am currently assembling my Bobcat 50 ~ that's what the colourful sticker on the box says (although curiously the enclosed instruction manual is labelled "Bobcat 52"). Anyway am tossing up which powerplant to use ~ an ASP 61 two stroke or a Saito 80 four stroke (the Saito would be turning a 3 blade broad pitched prop)

Would be very pleased to hear from anyone who has used either engine of that capacity.

"I popped out the control horns and moved them over one tick on the servo, so that the trailing edge was level with the back of the upper part of the stab..."
Do you mean you set the elevator in a slightly UP position?

Yes, the middle or bottom of the trailing edge of the control surface should be level with the upper trailing edge of the stab.
In other words the elevator should be UP about six to seven millimeters.

Also remember that the stance of the plane is important.