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Bobcat 50 notes (nitro Planes)

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Old 11-24-2009, 05:26 PM
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MartyH
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Default Bobcat 50 notes (nitro Planes)

I just finished building the Nitro Planes Bobcat 50. I said "build" because this is a "builder's ARF", it definately doesn't just fall together. Anyway, I have about an hour of runtime in the air now and it's a super smooth flyer! CG is set at about 10.25" and empty weight is 7 1/2 pounds with fixed landing gear. The engine is an Aviastar .46 with an O.S. #8 glowplug and running Wildcat 15% helimix fuel. There are a few things I would do differently if I built another one....

1) The Bobcat was built because I was looking for something to put time on an Aviastar .46 so the engine was a given. A 46 really isn't enough for this plane even though it is within the recommended range. It works but it really needs a .61 or even a .75.

2) I'd make sure I got an airframe designed for the fixed gear if I'm running fixed gear. This airframe was "retract ready" and was a pain in the butt installing fixed gear in it.

3) I wouldn't bother installing servos on the rudders. i'd save the money and the weight. I'd set them up in a fixed position with a pushrod so they could be statically adjusted. It would also help keep ballast weight in the nose down. I'm running 3.5 ounces in the nose even with the .46.

4) I installed 3" wheels in place of the tiny stock foam wheels since we have grass runways here.

Nitro Planes Bobcat 50 (gray & orange) $128 delivered to my door. I'd build another!

Marty


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Old 11-24-2009, 06:08 PM
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Default RE: Bobcat 50 notes (nitro Planes)

Here's my Neocat (same thing, different color). Mines electric on 6S Li-Po's. Pretty fast, I'd say about 120 out of a dive. I like the rudders, but I also used mini's on the ailerons and one elevator servo in the stab. .90 sized Scorpion outrunner....best part? No ballast! 6.5 pounds RTF, less fuel. :P
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Old 11-24-2009, 09:51 PM
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Default RE: Bobcat 50 notes (nitro Planes)


ORIGINAL: MartyH

1) It works but it really needs a .61 or even a .75.
I flew my friends with a tower .75 and a 3 bladed prop, it was a good combo.

2) I'd make sure I got an airframe designed for the fixed gear if I'm running fixed gear. This airframe was ''retract ready'' and was a pain in the butt installing fixed gear in it.
The stock nose gear constantly failed, what a PITA.


3) I wouldn't bother installing servos on the rudders. I'd save the money and the weight. I'd set them up in a fixed position with a pushrod so they could be statically adjusted. It would also help keep ballast weight in the nose down. I'm running 3.5 ounces in the nose even with the .46.
I bought one because I like the way my friend's FLEW but I'm thinking of leaving the rudders and stab off and flying as a flying wing or a canard. I just won a 30 size one I may test with, it'll be 4s electric.






4) I installed 3'' wheels in place of the tiny stock foam wheels since we have grass runways here.
We had to do that too. I was thinking of using DuBro plastic LG mounted under the motor. The stock main LG have the torsion bars mounted the wrong way.
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Old 11-25-2009, 07:37 AM
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MartyH
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Default RE: Bobcat 50 notes (nitro Planes)

There are so many versions of these planes. On mine, the torsion bar landing gear are mounted correctly.
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Old 11-30-2009, 01:03 PM
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Default RE: Bobcat 50 notes (nitro Planes)

I too have the Grey and Orange version. Yep, a builders ARF. No trouble with the fixed gear on mine, but replaced the missing screws for the fins. Used one servo for the elevator and using a .61 ST engine. Not sure how I want to mount the fuel tank.
I also have one in Patriot colors I'm going to sell. I think they are worth the money, but 8 servos for a four channel plane is a bit much.
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Old 12-01-2009, 08:03 AM
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Default RE: Bobcat 50 notes (nitro Planes)

Did you mount the servo up in the horizontal stab? I have seen that done.

If I had it to do over I would:

-pin the rudders with ground adjustable linkages
-use a single elevator servo mounted in the horizontal stab.
- find a way to get a square pack all the way up in the nose in front of the nose gear. The battery is a flat pack and located just behind the nose wheel currently.
-power with a Tower 75 2 stroke or similar.

My plane came in at 7 1/2 pounds with fixed gear as weighed on a calibrated digital scale. It's supposed to weigh 5 1/2 pounds according to the manufacturer. Not a chance! I'm using a lightweight .46 engine (it's not enough really) which required 3.5 ounces of lead up front with the 2700ma 5 cell battery. Imagine the ballast needed with a larger engine! So, I'd get those two rudder servos and one elevator servo off the tail which would help with that. I'd probably use a Tower 75 ABC engine.

I saved weight by using monokote instead of the supplied plywood hatches and screws in the bottom of the plane. It cost me weight when I installed 3" wheels for grass runway use. The supplied soft foam wheels were like and inch and a half and weighed nothing but they'd never get the plane out of the grass at our flying field.


I have a couple dozen flights on my Bobcat 50 now and really like it and the Aviastar 46 that's powering it. I just wish the plane was lighter and that I had more power (not the engine's fault). I will be building another at some point but for now I'm satisfied with what I have.
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Old 01-05-2010, 09:53 PM
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Default RE: Bobcat 50 notes (nitro Planes)


ORIGINAL: MartyH

2) I'd make sure I got an airframe designed for the fixed gear if I'm running fixed gear. This airframe was ''retract ready'' and was a pain in the butt installing fixed gear in it.
No kidding... I bought one what seems like a couple of years ago, and am just now getting around to building it. The vibe I get from this is like you said; It's not an ARF in the sense that it's convenient. Like for example a beginner who wants to fly sooner and doesn't want to build, so he gets a KAOS ARF and slaps it together one weekend. It seems more like a set of built wings and a fuselage and airplane raw materials. It's up to you to make it into a plane. The manual is useless, and I think it even shows the wrong CG. I literally tossed it aside. Well ok, I use it to mix epoxy on.

The gear situation is sink or swim. I just want to emphasize that unless they have changed the manual, you better know how to put gear blocks in a wing. No issue for a builder, but it's not plug n play for a beginner.

Anyway, I'm going to use a TT61 heli engine with 11x7 APC. I thought the bigger head would let the pusher run cooler at the expense of drag. Maybe too cool, we will see. I plan to just fix the rudders with dowel rods, and cover over the gaps, no adjustment. I am going to use a thin wing servo in the stab. Extension cable is needed.

http://www3.towerhobbies.com/cgi-bin...?&I=LXCRS4&P=7



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Old 01-07-2010, 01:49 PM
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Default RE: Bobcat 50 notes (nitro Planes)

Marty.......I also mounted the elevator servo in the tail boom. Using a ST .61 for power. Trying to use other tail boom servo for the rudders......a little tricky. Too cold to fly and cold in my shop too, I have cabin fever. I MAY have offset the engine a little, need to check it again. Is it STILL left thrust on a pusher if the prop tips are closer to the wing on left side?
I have not even checked wheels yet, but with an 11" prop, clearance is close.
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Old 01-07-2010, 06:45 PM
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Default RE: Bobcat 50 notes (nitro Planes)

I put an OS.50SX on one then a Jett .50 even bought the Jett pusher muffler for it.

YEP it needed some nose weight. flew ok but really needed more power.

I have the .25 size me thinks the JETT .50 will give it a kick in the pants
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Old 01-28-2010, 09:21 PM
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Default RE: Bobcat 50 notes (nitro Planes)

How are you guys setting the CG, with a full tank or empty? Inverted or Normal? Also what CG measurement do you like?

I have only flown my Bobcat 50 twice and it was very pitch sensitive and never really got to doing the dive check or inverted check to see how the CG was. Little nervous about future flights after the gear is all fixed. Thanks.
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Old 01-29-2010, 01:52 AM
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Default RE: Bobcat 50 notes (nitro Planes)

IIRC, the fuel tank is pretty much right over the CG so I'm not sure how much it matters if it is full or not. I used spring air retracts on mine and they worked well. Flew mine with a Tower .75 and an 11x8 Graupner pusher and it was pretty good power for it.



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Old 03-07-2010, 03:26 PM
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Default RE: Bobcat 50 notes (nitro Planes)

What is the correct CG for the 50" bobcat?
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Old 04-01-2011, 11:45 AM
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Default RE: Bobcat 50 notes (nitro Planes)

I just flew mine for the first time yesterday. On the first flight, it took alot of runway and then went almost straight up. Im thinking it is tail heavy but it did trim it out in flight with some up evevator. I have to check that. Im curious if the main landing gearis preventing the plane from taking off earlier since its placed kind of far back. I used alot of elevator and all of 300 feet of runway until it took off on a 60 degree climb until I corrected it. I may adjust the landing gear forward a bit, but I dont want the prop to not be protected. It has two flights on it but I think I will make sure the CG is 10.25in from frontmost leading edge. The manual sugests more then that. I agree, a .46 is not enough when going vertical, but a good flyer atleast.
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Old 04-01-2011, 04:25 PM
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Default RE: Bobcat 50 notes (nitro Planes)

ORIGINAL: JRAC19K

I just flew mine for the first time yesterday. On the first flight, it took alot of runway and then went almost straight up. Im thinking it is tail heavy but it did trim it out in flight with some up evevator. I have to check that. Im curious if the main landing gear is preventing the plane from taking off earlier since its placed kind of far back. I used alot of elevator and all of 300 feet of runway until it took off on a 60 degree climb until I corrected it. I may adjust the landing gear forward a bit, but I dont want the prop to not be protected. It has two flights on it but I think I will make sure the CG is 10.25in from frontmost leading edge. The manual sugests more then that. I agree, a .46 is not enough when going vertical, but a good flyer atleast.

I had a clone of a Bobcat that did this too. The mains are too far to the rear. I learned to get use to it, plus raise the nose by extending the nose wheel a bit helps it rotate. I would let it get plenty of speed for takeoff then nudge the elevator back but be ready to push it quickly back to level.

I remember my first takeoff with it. It was.........exciting.

If yours flairs nicely for landing, then don't mess too much with the CG.
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Old 04-24-2011, 02:28 PM
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Default RE: Bobcat 50 notes (nitro Planes)

What motor you using on 6S?
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