littlepiston

My Feedback: (12)

JJ1400 MW54 mw54SS jetcat p60 artes super beeL

marktur

Hi All,

We finally got a radar gun. Today we had a 15 knot headwind, and my upwind passes were clocked at 100.6. There were too many planes in the air for me to go downwind. My guess is that it is much faster downwind.

I still have not received my Weston pipe, but I'll report about that when I can.

opjose

With the Falcon, what you are looking for is PITCH SPEED.

The Falcon 1.20 has a lighter wing loading than the Bobcat .52.

Hardware wise they both have the same weight in servos, etc, but the Falcon has a bigger wing area.

I would assume that both engines will work. The FX 160 may give you better verticals, but the AX120 when combined with the right prop mayl unload in the air a bit better due to it's lower mass.

Add to that the lighter weight of the AX 1.20 and you could go either way.

I'm planning on putting in a 1.20 in mine and using high pitched props.

---

My Bobcat .52 SCREAMS with the GMS .76 engine.

A few Turbine guys commented that "I should have gotten one of those to learn how to fly the Kingcat type planes, using the Bobcat as a jet trainer... ".

marktur

My buddy who has the Falcon, just build the Bobcat 52, put a GMS 76 in it. He was significantly heavier than mine, but I didn't get to see it fly, as he was packing up when I arrived. He's got the Weston pipe on it, too. I'm sure we'll be racing and doing radar passes next Saturday.

I was really surprised that I was able to break 100mph! This was in level flight, across the runway after a shallow dive to pick up speed.

I'm still using the 11x7, I'm going to try the wood Zinger 11x8 next time now that I can measure.

PS. TERRY AND OPJOSE - The spoilerons are EXCELLENT!!!! I was having so much fun doing touch and go's yesterday, and the spoilers really made it look great on final and touchdown.

opjose

Yeah the spoilerons make landings easier.

Without them the plane is a handful to land.

I was having a REALLY hard time getting the Bobcat .52 down yesterday. The plane was all over the place.

I had been doing a lot of hard fast rolls prior to this...

After I got it down, I took it to check it out and discovered that I was flying with one working aileron.

The control horn had snapped in two at the base of the horn from the pressure!!!

The base was firmly planted in the surface as normal, and the horn itself was still attached to the metal clevis.

I guess I have to slow down those blindingly fast rolls at speed!

timevac

Hi all
I got a falcon 25 and am going to try os 32 with no landing gear ,no rudder servos.Intend to bugee launch and belly land
(SCARY!!) Total weight 3 lb 2 oz. wing loading only 18 0z/sq ft Might be a good way to wreck a plane though!!!

opjose

Why remove the landing gear?

Remember everything will be in the prop pitch... especially with that engine.

Give it a high enough pitch and the plane will scream... the problem is that the best I've found is a 9x7 3 blade MA prop...

I've flown my .25 at 3lbs 7oz w/o problems, especially once I got the spoileron's dialed in.

I'm considering raising this to raising this to 4lbs 1oz so I can put a second large battery pack in, that would permit me to double the voltage.
My electronics can handle 22v, and I hope to turn the .25 into a missle.

TUMBLER

My Feedback: (13)

I test flew my falcon .25 with Mega 22/30/3 on 4s and about 830 watts. It was ok. Probably 80-90mph. The speed control overheated and had to land deadstick and broke the landing gear block, so will add retracts or hand launch now. I need a better motor combo though cause it was pretty boring at that speed.

I re-covered the whole things cause the Chinacote was all wrinkled and added hatches and recessed all the servos.

Brian

opjose

Nice work.

Post a pick if you would of your servo and hatch assemblies.

TUMBLER

My Feedback: (13)

Here ya go. I mounted the elevator servo in the stab, not in the boom, cut holes in the ribs, and ran the wire through the stab.

opjose

Very nice particularly the rudder assembly.

You have it perpendicular to the control horn doing away with the angled linkage movement of the default setup.

TUMBLER

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Thanks man. Yeah thats the way it really should be and the way the real Bobcat is.

Eric Banner

Hi guys,

The canopy on my 50-size bobcat came off in flight yesterday. The canopy was completely destroyed but did not cause an appreciably trim change and I landed safely without further damage.

Can anyone assist with any information to help in locating a replacement?

Thanks,
Eric

Video of penultimate flight:

http://www.youtube.com/watch?v=OucKVUMAzKQ

TUMBLER

My Feedback: (13)

Eric,

I ruined the canopy on my .25 trying to take the tint off and they told me they don't have them. They are notorious for not having replacement parts. I am carving one out of foam or wood and making my own.

Brian

opjose

Just PM John here.

He's pretty good about providing parts as requested.

oneflyrn

I'm modifying mine to accept cheap hobbico mechanical retracts, a single retract servo for the mains and a standard servo to retract nose gear. No need to go air. Am anti-air retracts. Not that they are bad, just more expensive than necessary. Really liked the mechanicals in all of my Patriots (R.I.P. X 3) so going with them in this plane.

TUMBLER

My Feedback: (13)

delete

opjose

Tumbler:

Did you adjust your ESC's timing to your motor.


I find that it makes a HUGE difference.

You need to hook up a watt meter to reveal what is the best timing configuration.

I tripled my motor's initially anemic output by adjusting the timing and playing with prop sizes.

IMHO with your setup you should be running at LEAST a 10x8 3 blade prop.

TUMBLER

My Feedback: (13)

No waaaay. I am drawing 60amps already with an 8x8. That would be way beyond what the motor, speed control can take. I need to get something that will draw somewhere around 40-50 amps, give me at least 60-70 ozs of thrust and have a picth speed of over 130+ to get it to fly close to how I want.

Brian

opjose

Strange, I put a 10x7x3 MA Prop on mine and it's drawing about 420 watts at 30 amps.

I haven't measured it but I believe I'm getting about 58+ oz of thrust as the plane which weights 3lb's 6oz easily lifts itself and accelerates when pointed straight up.

TUMBLER

My Feedback: (13)

Are you sure you have the same motor? I am well over 800 watts on mine with an 8x8. Mega 22/30/3. Mine is direct drive. Are you using a gearbox maybe?

opjose

No it's not the same motor.

It's a Tower Pro ( sold as the BP2915D at BP Hobbies ).

This motor has a max capacity of about 500 watts, and is supposed to be the equivalent of a .30 sized glow engine.

Since yours is far more powerful, I would assume that it needs an even bigger prop to be able to draw more power.

TUMBLER

My Feedback: (13)

No it doesn't really work that way. It depends on a lot of factors. The KV of the motor, the number of cells you use, etc. For example, on 4 cells and a 8x8 prop mine draws 60 amps and 800 watts. On 5 cells I would have to drop the prop down to probably a 7x7 or less because the motor will turn higher rpms and draw more . The idea being that the more cells you add, the lower your amp draw will be. High volts/low amps is the key to power. You have to find the combination that lets you stay in the range of your motor, speed control, and battery and still give you waht you want.

opjose

Yeah I should have asked you how many cells, etc.

So what are you running?

TUMBLER

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I am running 4 cells. You are using an outrunner, if I am not mistaken. I am using and iunrunner. Outrunners wing bigger props at slower rpms.