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 11-19-2007, 01:30 PM
  #401
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Default RE: Its Bobcat nice

I recommend using the rudders, I use them often on landing and are actually very effective for knife edge flight and four point rolls as well as the usual rudder uses like coordinated turns.
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Old 11-20-2007, 03:51 PM
  #402
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I was pleasantly surprised how well the rudders worked.

Blessings, Terry
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Old 11-21-2007, 04:28 PM
  #403
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So you all would say rudders are a must for the take off roll, nose wheel alone wouldn't be enough?
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Old 11-21-2007, 10:16 PM
  #404
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Default RE: Its Bobcat nice

I would say you NEED the rudders.

The nose wheel gets you aligned on the runway, but it becomes "light" quickly and then it is up to the rudders to keep the plane tracking straight.

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Old 11-24-2007, 01:48 AM
  #405
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Default RE: Its Bobcat nice

The rudders are not needed....I have them on mine, but never used them. A
friend had a new one at the field a couple weeks ago....he didn't even install
the rudders. It flew fine.

FBD.
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Old 11-24-2007, 11:46 AM
  #406
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Default RE: Its Bobcat nice

I dunno. I use them a lot to keep the plane down the centerline.

Once it starts getting light, the nose gear is somewhat worthless.

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Old 11-26-2007, 08:59 PM
  #407
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Default RE: Its Bobcat nice

Guys,

I will be receiving my Bobcat this week. After reading all the threads I could find I still have a couple of questions.

First, I thought I saw a post where someone ran their exhaust down through the wing to the bottom. Is that possible and how is it accomplished? Does anyone make a muffler for pushers?
I hate all the goo that assocoated with glow and I'm sure this plane gets coated with the exhaust blowing forward into the wind.

Second, I see a lot of guys using the Tower 75 engine. Would the AX 75 produce more power? Would it be worth the extra $$$

Thanks,
mike

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Old 11-28-2007, 12:14 AM
  #408
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Default RE: Its Bobcat nice

Mike....the AX will not make any more power for the money. []

The biggest prop that fits on the Bobcat is a twelve incher.

I would go for the Tower .75.

FBD.
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Old 11-28-2007, 01:15 PM
  #409
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Default RE: Its Bobcat nice

Quote:
ORIGINAL: nrthwing

Guys,

I will be receiving my Bobcat this week. After reading all the threads I could find I still have a couple of questions.

First, I thought I saw a post where someone ran their exhaust down through the wing to the bottom. Is that possible and how is it accomplished? Does anyone make a muffler for pushers?
I hate all the goo that assocoated with glow and I'm sure this plane gets coated with the exhaust blowing forward into the wind.

Second, I see a lot of guys using the Tower 75 engine. Would the AX 75 produce more power? Would it be worth the extra $$$

Thanks,
mike

I'm using a GMS .76, although the Tower is rated slightly better...

As far as the exhaust.



Hint:

Venom makes a set of exhaust deflectors that are slightly longer than most.

My Dubro/Tower exhaust deflectors kept coming out, even though I had glued them in place with Canopy Glue...

I then switched to the slightly longer Venom deflectors and I have had no problem since.

They also make a smaller deflector for race cars, which I mounted on the bottom of my bobcat to further direct the exhaust down and back.

This mates with the venom deflector, and I've affixed them together with canopy glue.

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Old 11-29-2007, 08:38 AM
  #410
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Has anyone measured the all up weight of a Bob Cat with a glow engine. I know what the manufacturer suggests but it comes from someone who leaves the prop nut off for pictures.

Bill
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Old 11-29-2007, 09:03 AM
  #411
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Default RE: Its Bobcat nice

Quote:
ORIGINAL: Flyboy Dave

Mike....the AX will not make any more power for the money. []

The biggest prop that fits on the Bobcat is a twelve incher.

I would go for the Tower .75.

FBD.
The thrust would be interesting to know if you have measured it.

Bill
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Old 12-01-2007, 10:02 AM
  #412
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Default RE: Its Bobcat nice

Greetings, My best friend and I have been flying the Bobcat's for a while now and we have ended up using YS 45's with tuned pipes. We are presently turning about 18,000 RPM's with 10-6 APC props. The 45 engine has been doing very well and the plane flies very good. Have had no major problems except when I flew it the first time. Had trouble getting it to rotate but figured that out pretty quickly. Had to set the elevator up trim a little more. It was trying to hold the nose down on takeoff. Overall I have enjoyed the plane very much. It is not the rocket that it looks like it would be but we are averaging a little over 100 MPH with the setups we have now. Very stable plane. Thinking about getting the 120 and see what I can do with it too.
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Old 12-01-2007, 12:42 PM
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Landing gear install help. I have looked over the pictures for installing the stock landing gear in the wings, huh? Can someone please explain the install. I cannot figure it out. The block of wood with the covering and slot in it for the wire does not look like it will fit and be flush with the wing surface. Also what keeps the wire gear from just falling over? Seems I must have to drill a hole in the block for the wire to go in but ???????? So I am not sure how to proceed. Thanks in advance........................
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Old 12-01-2007, 09:34 PM
  #414
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Figured the landing gear out, sometimes I am a real dummy.................
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Old 12-01-2007, 11:49 PM
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Default RE: Its Bobcat nice


Quote:
ORIGINAL: nrthwing

Guys,

I will be receiving my Bobcat this week. After reading all the threads I could find I still have a couple of questions.

First, I thought I saw a post where someone ran their exhaust down through the wing to the bottom. Is that possible and how is it accomplished? Does anyone make a muffler for pushers?
I hate all the goo that assocoated with glow and I'm sure this plane gets coated with the exhaust blowing forward into the wind.

Second, I see a lot of guys using the Tower 75 engine. Would the AX 75 produce more power? Would it be worth the extra $$$

Thanks,
mike

Here is the answer to your question

O.S. .75 AX ABL Engine

SPECS: Displacement: 0.75 cu in (12.3cc)
Bore: 1.02" (25.8mm)
Stroke: 0.93" (23.5mm)
Practical RPM: 2,000-16,000 r.p.m.
Power Output: 2.4ps/15,000 r.p.m.
Weight: 20.39 onuces (578g) w/o muffler
26.46 ounces (750g) w/ muffler
Recommended Props: 14x6, 14x8, 15x7
1 ps = 735.499 watts, 2.4px*735.499 = 1765.1976 watts output at 15,000rpm




Tower Hobbies .75 Ball Bearing ABC Schnuerle & Muffler

SPECS: Displacement: 12.21cc (.75 cu in)
Bore: 26mm (1.02"
Stoke: 23mm (.91"
Horsepower: 2.2 BHP at 15,600 RPM
Weight: 652g (23.0 oz) (with Muffler) (jl10/00)
Weight: 535g (18.9 oz) (without Muffler)
Recommended Props: Break In: 12x6 or 13x6
1 BHP =745.7watts, 2.2BHP*745.7=1640.54 watts @ 15,600 rpm


So if you look at pure watt per rpm efficiency the OS is 10.64% more efficient than the Tower motor.

@ 13,000 rpm that is a difference of 162 watts. The OS will spin a larger propellor which may be where you will see the advantage of the 10% greater efficiency. Not to mention those large props won't fit between the booms of the Bobcat. In this case I seriously doubt you will see the benefit of your extra $100 bones by buying the OS, the OS is also heavier than the Tower motor which means you will need more nose weight and make wing loading that much higher.

I would like to see what the Tower .75 would do with a tuned pipe on this plane.

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Old 12-10-2007, 09:03 PM
  #416
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Default RE: Its Bobcat nice

who makes a tuned pipe for the tower 75
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Old 12-10-2007, 10:55 PM
  #417
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Default RE: Its Bobcat nice

Macs is easy....

First you will need a header...

http://www.macspro.com/headers_side.asp

And then a Pipe.....

http://www.macspro.com/tunedpipes.asp

I have also heard very good things about the Jett Mufflers

http://www.jettengineering.com/accy/jettstream.html

I believe some have purchased rear exhaust mufflers for the Bobcat from Jett?
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Old 12-11-2007, 10:32 PM
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Default RE: Its Bobcat nice


Quote:
ORIGINAL: orstraycat

Landing gear install help. I have looked over the pictures for installing the stock landing gear in the wings, huh? Can someone please explain the install. I cannot figure it out. The block of wood with the covering and slot in it for the wire does not look like it will fit and be flush with the wing surface. Also what keeps the wire gear from just falling over? Seems I must have to drill a hole in the block for the wire to go in but ???????? So I am not sure how to proceed. Thanks in advance........................
I put a hole in both ends of the slot. The slot runs from front to back which seems incorrect. There does not seem to be a hardwood block to hold the gear in either end of the slot. With the wheels in the forward position the other end of the wire will stick through the top of the wing. Haven't decided how to resolve the issues which are design problems. Or lack of design.

Bill
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Old 12-12-2007, 12:38 AM
  #419
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Default RE: Its Bobcat nice

Quote:
ORIGINAL: BillS


Quote:
ORIGINAL: orstraycat

Landing gear install help. I have looked over the pictures for installing the stock landing gear in the wings, huh? Can someone please explain the install. I cannot figure it out. The block of wood with the covering and slot in it for the wire does not look like it will fit and be flush with the wing surface. Also what keeps the wire gear from just falling over? Seems I must have to drill a hole in the block for the wire to go in but ???????? So I am not sure how to proceed. Thanks in advance........................
I put a hole in both ends of the slot. The slot runs from front to back which seems incorrect. There does not seem to be a hardwood block to hold the gear in either end of the slot. With the wheels in the forward position the other end of the wire will stick through the top of the wing. Haven't decided how to resolve the issues which are design problems. Or lack of design.

Bill
Sounds like something is drastically wrong here! In mine and I assume everyone else's planes there was a hole in the end of the slot and the slot was in a block of well somewhat hardwood. And yes they run front to back, you use two nylon hold downs over the horizontal part of the wire on each landing gear.

I loaded a picture of how the gear fit in the slots, this was a picture I took to show that they originally sent me two of the same landing gear so ignore that part.
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Old 12-12-2007, 12:27 PM
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Default RE: Its Bobcat nice

Yes my gear location looks like your picture.

The front of the slot is 3 1/4" behind the CG and the rear of the slot will put the wheel CL 5 7/8" behind the CG. 10 1/4" CG. My experience with other types of airplanes indicates the airplane will not rotate. The airplane will need positive ground incidence and simply fly off the ground when it gets up to speed.

I will rely on your experience and see what happens.

Bill
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Old 12-12-2007, 12:46 PM
  #421
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Default RE: Its Bobcat nice

I think he has the retract ready version and is trying to put in the fixed gear, which is why he is confused about the installation.

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Old 12-12-2007, 12:54 PM
  #422
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Default RE: Its Bobcat nice

As far as I know, there is only a retract version on the 120 size. I have not seen a smaller size fitter for retracts. I did not use the wire gear but bought Fultz's new Scorpion gear (look at their website). It is a very solid and stable gear.

R/C Foolish
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Old 12-12-2007, 01:02 PM
  #423
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Quote:
ORIGINAL: R/C Foolish

As far as I know, there is only a retract version on the 120 size. I have not seen a smaller size fitter for retracts. I did not use the wire gear but bought Fultz's new Scorpion gear (look at their website). It is a very solid and stable gear.

R/C Foolish
My Bobcat .50 came retract ready. ( it's an option on the NP web site... )

I put in Robart 51x retracts which have worked well.


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Old 12-12-2007, 01:30 PM
  #424
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Well I am probably also confused, which is nothing new and wouldn't be the first time. What is the difference when retract ready? My airplane looks like it was made for fixed gear.

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Old 12-12-2007, 01:36 PM
  #425
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Default RE: Its Bobcat nice

The retract ready have the blocks and cutouts for the retracts.

Hopefully you can see it in this picture



What is confusing the poster is that the plane comes with a set of wooden blocks that get inserted into the retract area here...



These get epoxied in place and hold the gear wires BELOW the surface of the wing. Then the supplied covers get put in to fill the hole in the wing area.

FYI: the retract gear area really needs re-inforcement as it gets a LOT of abuse even on gentle landings.

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