Extreme Speed Prop Planes Discuss the need for speed with fast prop planes (Screamin Demon, Diamond Dust, Shrikes or any REAL sound breakin'''' plane)

Its Bobcat nice

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Old 12-31-2007, 09:45 AM
  #451
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Default RE: Its Bobcat nice

Allstardude17,

opjose is correct the Bob Cat is an airplane for the experienced flyer with considerable experience. It also requires building experience because of the lack of instructions.

Below are two URL's of airplanes that might be better first time airplanes.
http://www.texasrcplanes.com/arftr.html
http://www.texasrcplanes.com/arfsptr.html

Good luck.

Bill
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Old 12-31-2007, 03:09 PM
  #452
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Quote:
ORIGINAL: allstardude17

hey thanks for that site..sounds like a good idea..i have talked to people that have been flying for years and say they still crash every now and then..so insurance is def a good idea..thanks for the help
Remember that the insurance is not for your plane, it is so YOU don't get sued by someone and have to pay for it.

To make that insurance effective, you must ONLY fly at AMA sanctioned airfields, which means you must be a member of a club and fly at their field.

Many clubs have great facilities.

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Old 01-01-2008, 04:37 PM
  #453
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Default RE: Its Bobcat nice

ohhh..ok..makes sense
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Old 01-01-2008, 04:43 PM
  #454
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Default RE: Its Bobcat nice

Belonging to a club is the best way to keep this hobby/sport going.

All two often municipalities and cities are enacting ordinances against RC craft because of the idiot who decides to fly his electric or glow plane on his own.

People become concerned or scared of what they perceive to be a danger, and the next thing you know such activity is banned over a wide area.
Already there are too many such regulations and restrictions.

All it takes is one overzealous newbie to kill someone with his jet or plane and RC will see a serious assault by the rest of the country.

The clubs promote safety and community conciousness and shed a very positive light on the sport/hobby when properly run.

Check em out. It's worth doing.

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Old 01-05-2008, 10:31 PM
  #455
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Default RE: Its Bobcat nice

I've started a build thread on my bobcat. Need to take some more pics of the progress.

http://www.rcgroups.com/forums/showthread.php?t=790307
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Old 01-05-2008, 10:42 PM
  #456
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Default RE: Its Bobcat nice

Nice thread, although I'm a bit surprised to see that you are going to lock out the rudder.

I find that I need it for landings to keep the plane on the runway as it runs out.

The nose gear doesn't get enough authority until the plane has significantly slowed down.


A sure sign of a draggy airframe is that the plane slows down quickly once you chop throttle.

I've had problems landing mine as it seems to keep moving forever once I chop the throttle on landing.

I wouldn't quite call it draggy, especially with the performance I've been getting with a GMS .76 engine.


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Old 01-06-2008, 01:29 PM
  #457
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Default RE: Its Bobcat nice


Quote:
ORIGINAL: opjose


Quote:
ORIGINAL: allstardude17

hey thanks for that site..sounds like a good idea..i have talked to people that have been flying for years and say they still crash every now and then..so insurance is def a good idea..thanks for the help
Remember that the insurance is not for your plane, it is so YOU don't get sued by someone and have to pay for it.

To make that insurance effective, you must ONLY fly at AMA sanctioned airfields, which means you must be a member of a club and fly at their field.

Many clubs have great facilities.

Are you saying that the AMA insurance is only good if you fly at a sanctioned Field? That is not my understanding. I will check into it but AFAIK it covers you whenever you fly. I'm not saying it is not a good idea to join an AMA sanctioned club, it is. I belong to one myself, but I flew at Mile Square Park in Orange County for years and it was a public park where anyone could fly. I am certain our insurance was good there because I knew a few guys who needed and used it.

Blessings, Terry
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Old 01-06-2008, 02:05 PM
  #458
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Quote:
ORIGINAL: still4given

Are you saying that the AMA insurance is only good if you fly at a sanctioned Field? That is not my understanding. I will check into it but AFAIK it covers you whenever you fly. I'm not saying it is not a good idea to join an AMA sanctioned club, it is. I belong to one myself, but I flew at Mile Square Park in Orange County for years and it was a public park where anyone could fly. I am certain our insurance was good there because I knew a few guys who needed and used it.

Blessings, Terry
Yup check the verbiage.

You must be flying on a club field and in turn the club must belong to the AMA.

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Old 01-06-2008, 02:54 PM
  #459
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Yeah its been a tough decision for me. I plan to wire up the tail booms for this reason. If I find I can't handle the plane well without rudder I will be popping the servos in for it. I have a nice wide runway to land on so we'll see! Whats the final concensus on a good CG? Also any suggestions on setting up the rake on the landing gear (ie nose down, neutral, or nose up?).

Quote:
ORIGINAL: opjose

Nice thread, although I'm a bit surprised to see that you are going to lock out the rudder.

I find that I need it for landings to keep the plane on the runway as it runs out.

The nose gear doesn't get enough authority until the plane has significantly slowed down.


A sure sign of a draggy airframe is that the plane slows down quickly once you chop throttle.

I've had problems landing mine as it seems to keep moving forever once I chop the throttle on landing.

I wouldn't quite call it draggy, especially with the performance I've been getting with a GMS .76 engine.


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Old 01-06-2008, 03:39 PM
  #460
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Default RE: Its Bobcat nice

....10.3" on the cg, nose up attitude....1/8" "up trim" in the elevator.

FBD.
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Old 01-06-2008, 11:09 PM
  #461
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Default RE: Its Bobcat nice

Did any of you guys use an incidence meter to set the tail boom? Seems like there is so much room for error?!
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Old 01-06-2008, 11:25 PM
  #462
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Default RE: Its Bobcat nice

The booms screw onto the wings with no wiggle room. The horizontal stab fits into recesses
in the booms, and there is no wiggle room there either. But the way they fly shows that it is
set up quite nicely.

FBD.
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Old 01-07-2008, 07:58 AM
  #463
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Default RE: Its Bobcat nice

Yes there is a lot of room for manufacturing error and the people manufacturing are not modelers. Shimming the front tail section mount up 1/64" on the wing changes the stab angle over 6 degrees. A wide range of stab angles might not effect the way it flies. But it seems logical based on other airplanes that the speed would be affected. On conventional airplanes as the aileron sweet spot is found the speed goes up significantly maybe 8 to 10%.

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Old 01-07-2008, 09:30 AM
  #464
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Default RE: Its Bobcat nice


Quote:
ORIGINAL: opjose


Quote:
ORIGINAL: still4given

Are you saying that the AMA insurance is only good if you fly at a sanctioned Field? That is not my understanding. I will check into it but AFAIK it covers you whenever you fly. I'm not saying it is not a good idea to join an AMA sanctioned club, it is. I belong to one myself, but I flew at Mile Square Park in Orange County for years and it was a public park where anyone could fly. I am certain our insurance was good there because I knew a few guys who needed and used it.

Blessings, Terry
Yup check the verbiage.

You must be flying on a club field and in turn the club must belong to the AMA.

DO you have a link for that? I looked through everything I can find and I see no verbiage that limits the insurance coverage to AMA sanctioned fields. I would really like to see where you got that.

Thanks, Terry
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Old 01-07-2008, 12:06 PM
  #465
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Default RE: Its Bobcat nice


Quote:
ORIGINAL: still4given


DO you have a link for that? I looked through everything I can find and I see no verbiage that limits the insurance coverage to AMA sanctioned fields. I would really like to see where you got that.

Thanks, Terry
Found it.

I misquoted ( senior moment... ).

The statement applies to people involved with the "introductory" pilot program that states that coverage is NOT provided on non AMA sanctioned sites.

That is the statement I remembered, but I forgot that it only applied to introductory members.


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Old 01-07-2008, 01:03 PM
  #466
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Default RE: Its Bobcat nice

Are you guys gluing the wings to the fuse or just bolting them in? Same for the booms?
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Old 01-07-2008, 01:09 PM
  #467
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Quote:
ORIGINAL: z06kal

Are you guys gluing the wings to the fuse or just bolting them in? Same for the booms?
I glued my wings in for strength, but bolted the booms in so I could get to the wiring in case I wanted to replace a servo.

Whatever you do, make sure you allow for servo removal or replacement...

If you don't leave enough of the extension exposed, this can be difficult if you forget.

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Old 01-07-2008, 01:30 PM
  #468
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Default RE: Its Bobcat nice

I glued my wings on too, and I drilled out and through bolted the booms to the wings.
The booms are held on with super wimpy nylon bolts....no joy. I used steel screws with
washers and nylon locking nuts under the wing to bolt the booms on. They aren't going
to fall off. I also epoxyed in and screwed on the horizontal stab.

FBD.
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Old 01-07-2008, 06:28 PM
  #469
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Default RE: Its Bobcat nice

I bolted the wings on with 1/4" nylon bolts, changed the boom hold down bolts to steel and re-enforced the boom hold down nut installations with plywood and epoxy.

I have not updated this but it details how I put the wings on.

http://www.rcuniverse.com/product_gu...65&kit_id=4554
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Old 01-08-2008, 10:17 AM
  #470
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Default RE: Its Bobcat nice

I bolted the tail section to the wing with steel bolts and the wings with nylon bolts. The airplane would be difficult to repair if it could not be disassembled. Of course some don't ever need to repair. Not me. I need to repair often.

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Old 01-09-2008, 11:50 AM
  #471
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I went a little overboard on the rear mains (wanted to make sure it would clear my 12" prop good). As a result, my nose gear is about 1/2" shorter than the rear mains. This will give a couple of degrees of negative incidence. I saw some reports of trouble rotating with negative incidence. Does anyone have any first hand experience with this on this plane? I have a 600x100 ft runway to work with and I have a hard time believing with such a very large elevator that the plane won't rotate when it’s going 50mph down the runway and you give it full deflection? I’m also considering using spoilerons for take off to counteract any negative lift the wing is producing, I heard that the plane ballooned pretty good when spoilerons were used and maybe this can be a solution?
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Old 01-09-2008, 11:58 AM
  #472
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Default RE: Its Bobcat nice

I can attest to the fact that you MUST have positive incidence on this plane.

Otherwise it will run down the runway forever until it has sufficient lift to overcome the negative incidence, at which point it will shoot straight up w/o enough airspeed.

Change things to at the very worst have zero or a slight positive incidence.
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Old 01-09-2008, 01:05 PM
  #473
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Opjose: Interesting so you had the model run down forever and then suddenly shoot straight up, stall and fall back down misserably? My plane should have unlimited vert so not sure how bad this will effect me. You could pull the nose back down before it stalled once it was airborne? Also how bad was your negative incidence, what was the difference between rear wheels and nose wheel?
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Old 01-09-2008, 01:17 PM
  #474
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Quote:
ORIGINAL: z06kal

Opjose: Interesting so you had the model run down forever and then suddenly shoot straight up, stall and fall back down misserably? My plane should have unlimited vert so not sure how bad this will effect me. You could pull the nose back down before it stalled once it was airborne? Also how bad was your negative incidence, what was the difference between rear wheels and nose wheel?
I got the plane's nose down, but I was lucky because it was wallowing around.

Having "unlimited" vertical really has nothing to do with it.

With the .76 engine I have no problems what so ever with verticals.

The problem is that the wings suddenly go into a high alpha and the control surfaces become ineffective, causing the plane to wallow around, while you are very close to the ground. I almost lost the plane as a result.

After this I adjusted the incidence and take offs have been uneventful.
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Old 01-09-2008, 01:28 PM
  #475
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How bad was your negative incidence? Ie difference in inches between mains and nose?
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