opjose

Yup a smaller prop seems more efficient on a Pusher for some reason.

I'm running an 11x8 with a GMS .76 engine which is just about perfect, though in a tractor config this prop would normally be too small.

Bobby V

Has anyone used electric retracts in the Bob Cat 50? And could you tell me what I should use.
Thanks,
Bobby V

cyborg1

Opjose, thanks for the info. BTW, I noticed that at about half throttle, the engine runs rough, causing a lot of vibration to the airframe. Half throttle is my cruising speed, and basically where I spend most of my flying time. Is this due to insufficient runin time on this engine, or should I lean the low speed needle a bit nore? I've adjusted the low speed needle for acceptable throttle response, but it is still rich, as I've only run 2 tanks on the test stand. I've also removed the baffle in the power box muffler. Could this be casuing resonance problems too?

opjose

Cyborg1

A rough running engine should not vibrate per-se.

Vibration over and beyond normal engine running is usually do to other factors.

e.g. your make have a resonance that only developes at a certain engine speed range.

Your selected prop may cavitate the air at that speed, etc.

However you certain should attempt to fine tune the engine.

Given you said "powerbox" you have an O.S. AX I presume.

It would be ok to start adjusting the LS needle by now.

Go ahead and bring it in to the point that the engine will NOT hold an idle, then bring it back out about 1/2 turn.

Then test the transition.

airborne14830

I have started to assemble my bobcat 50. My wing halves have blind nuts where the small bar goes. Will the 6-32 screws be enough to hold the wing on along with the large bar? Also, my horizontal stablizer has only one screw for each side, are folks epoxying the stab in place or will th screw be enough to hole the stab?

Crazy4Flight

My Feedback: (540)

Airborne,

screws are not 6-32 they are METRIC.
use locktite or similar product on the screws holding the stab,
make that all the metal screws into metal parts.

Some folks have put the elevator servo in the stab replacing the dual setup. Hitec thinwing works great.

The wood plate, holding the blindnut, in the front of the tailbooms needs to be re-glued!!
Mine came loose!! add triangle stock to secure them.

Start at the begining of this thread for tips from others.

C4F

airborne14830

thanks for the feedback. i will add support to the tail boom. I think I ned to purchase a right angle srew driver to get a good bite on the the screws. My hands are to big for the opening.

Xairflyer

My Feedback: (1)

Yes very important to reinforce the mountings of the captive nuts in the tail booms, I added extra strips of wood to hold them in and extra epoxy.

You dont need to glue in the stab, but it is good practice to check all the screws, booms etc after each days flying to be sure.

BillS

The screws holding the horizontal stabilizer will come loose. I put a dab of Titebond on the screw head after the screw came loose several times. Nylon screws would have been a better choice to hold the horizontal stabilizer.

After several nasty landings I added 1/64� lite ply to reinforce the outside of the booms at the stabilizer screw holes.

Bill

Bobby V

I have a Bob Cat %0 and I would like to put electric retracts in. Can some one tell me what to use.
Thanks.
Bobby V

opjose

Any set of standard sized retracts designed for planes in the .40 - .60 range should work.

However because the plane is NOT designed for electric retracts, you'll have to make some modifications.

I would suggest retracts where the retract servo retainer is built into the retract itself... though this will require two retract servos for the wings.

IMHO air is easier to use.

Romulo

Hi,

Yesterday i tried to take off for the first time with my bobcat 50.

My set is:
OS55AX with 11x7P
3070 kg
CG at 268mm

I just run some meters at full trotlle and the bobcat doesn't gave any signal for take off or just to put the nose up !!
I tried to push all elevator but.......nothing !! Is like he have glue on the wheels !!

When it is on the ground the plane are leveled, so should i put the nose up in the front wheel ?? It helps ??

Does anyone have some idea what should i do ??

Thanks,

[img][/img]

Romulo

[quote]ORIGINAL: Romulo

Hi,

Yesterday i tried to take off for the first time with my bobcat 50.

My set is:
OS55AX with 11x7P
3070 kg
CG at 268mm

I just run some meters at full trotlle and the bobcat doesn't gave any signal for take off or just to put the nose up !!
I tried to push all elevator but.......nothing !! Is like he have glue on the wheels !!

When it is on the ground the plane are leveled, so should i put the nose up in the front wheel ?? It helps ??

Does anyone have some idea what should i do ??

Thanks,

opjose

Two things to do.

- When the elevator stick is at neutral, make sure that the trailing edge of the Bobcat's elevator is level with the TOP of the rear of the horizontal stabilizer.

- The plane should sit with a slightly nose high attitude to the wings. Adjust the landing gear lengths so accomplish this.

In other words it needs a positive angle of attack to the wings or else it WILL stick like glue to the runway!

1-2 degrees are all that is needed.

Romulo

Hi,

Thanks, it was just my idea but because it my first time with this kind of planes i just wont to make sure.

I am also using FLAPERONS, do you know how mutch % should i use ?? i just defined 50% and 70%, its too much ??

opjose

Why Flaperons?

What this plane needs are NOT flaperons but SPOILERONS instead!

Using flaperons actually makes the plane HARDER to land.

Spoilerons help kill lift and slow it down.

Flaperons also push the nose down, so if you used them for takeoff, this may also have exacerbated the problems you are having.

Instead of Flaperons dial in about 1/4" of SPOILERONS, and use this for landings, not takeoffs.

You'll be able to keep the nose higher on landings with the spoilerons w/o having the plane stall out on you so quickly.
This will cause it to act as an air brake.

BTW: Have you flown one of these before?

They are very different than a standard plane, and take some getting used to.

Romulo

The idea of Flaperons i saw in this forum someone who use it, but if it's true that can brake the plane can also put the nose down and for this kind of plane it's not so good on landing.

Maybe you are right, i will try spoilerons, if i can take off first !! ;-)

Can you give me your complete set for your bobocat ??

Actually it's my first time with this kind of planes, but sometime shoud be the first !

It's just take off and see what happends....

Dauntae

I tried the spoilerons and they acted like the elevator, So try it up high and don't have it go too much, 1/4 inch I found to be a little too much, and wait until the plane slows down before putting them on, or it will be like giving full up and it will just climb on you, and you will have to go around for another try. I actually prefer to just land it without the spoilerons and find it easier to control the nose up with the elevator, but it's just a matter of preference I guess. Good luck with it and have fun, it is a lot of fun flying these Bobcat's

Dauntae

opjose

Yes Spoilerons are really to be used when you've slowed the plane down for final approach and they will raise the nose as you've discovered.

It helps to practice with the plane high, until you get the hang of it. You'll find that it is best to raise the spoilerons once it gets below a certain throttle & speed setting.

Once you get the hang of it, you'll discover that it is MUCH easier to land it with the spoilerons on as the plane has much less tendancy to roll over with a tip stall. The airbraking effect of having the nose high also helps slow it down on landing.

I mixed in about 4-6% down elevator with the spoileron to compensate for the slight nose up tendancy ( this is more pronounced at higher speeds, but not uncontrollable ).

airborne14830

i am assembeling my bobcat50 and I don't have the manaul, but what I need to know for now is how far from the fire wall is the engine suposed to be mounted in inches please? Also the low and high rates for the control surfaces.

thanks

opjose

PM me your e-mail address and I'll e-mail you the manual.

It is 7.5 Megs in size so make sure that you give me an address that can handle messages of this size.

airborne14830

Opjose,

check your inbox for the e-mail address. thanks for doing this

Dig it

Flaperons actually caused me to crash. The plane stalled to the right more than once do to low speed and I'm thinking a slight aileron input. No biggy, it can be fixed but be very very cautious with this type of setup. Spoilerons work well but to be honest the plane lands fine without anything other than normal flight surfaces.

Dale

opjose

You have mail!

opjose

Flaperons help to kill lift for a steeper, but faster approach, which the Bobcat loves to do...

They also help to hold the nose high once the main wheels touch down.

Only a slight amount is required, normally only 1/4" or so.

Unless you install brakes or a friction system, the Bobcat loves to roll, and roll, and roll on the ground once it is down, and that is where the flaperons help immensely.

You are not advised to try to use them as you would flaps, in that they DO NOT help the plane fly more slowly... they help landings and rollouts instead.