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Nitro models pusher Bobcat?

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Old 05-02-2007, 02:02 PM
  #1601
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Default RE: Nitro models pusher Bobcat?

OK, I had a bad day. Tried my maiden flight on the Bobcat and had a serious wreck. Everything looked good on the ground but the engine went rich on take off and at about 20 feet in the air the engine just quit. The plane was at relatively low speed and immeadiately rolled to the right and went in nose first. There was absolutly no chance of recovery. There is severe damage to the fuselage, it is almost complety broken off at the wing. Our local expert, says it looked very tail heavy acting to him, however, we checked the CG after the accident and it was right on the 10.3 inches even with a full tank of fuel. I'm not sure at this point if the plane is repairable. This is very disappointing but certainly not the first time I have ever lost an airplane. And, yes, to those who wish to ask, I did have a deflector on the Tower 75 exhaust pipe to keep back pressure from richening the egnine.

Best wishes and good safe flying.

Heli-NuBee (Roger)
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Old 05-02-2007, 06:50 PM
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Default RE: Nitro models pusher Bobcat?

Quote:
Our local expert, says it looked very tail heavy acting to him, however, we checked the CG after the accident and it was right on the 10.3 inches even with a full tank of fuel.
Sorry to hear this story, losing a plane on the maiden is a bummer for sure. Not sure how your local expert was able to conclude that the plane was tail heavy if the engine flamed out on takeoff at only 20 feet off the ground. The plane was most likely just slightly past stall speed and nose up when the engine quit and there's only one place to go after that. Checking the CG after a bad crash is pretty tough to do, hopefully you double checked it before the flight. At any rate, I doubt the CG had much to do with the mishap. Hope your next outing is better.
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Old 05-02-2007, 06:58 PM
  #1603
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Default RE: Nitro models pusher Bobcat?

Quote:
ORIGINAL: Heli-NuBee

OK, I had a bad day. Tried my maiden flight on the Bobcat and had a serious wreck. Everything looked good on the ground but the engine went rich on take off and at about 20 feet in the air the engine just quit.
Sounds like your engine may have gone lean, if at an vertical angle the engine quit. or maybe there were fuel draw problems. I'm assuming the tanks were plumbed correctly.
The Tower .75 likes to run more on the rich side but does not like to run lean at all.
Was the engine broken in? What did the glow plug look like after the mishap?
Sorry to hear...
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Old 05-02-2007, 08:58 PM
  #1604
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Default RE: Nitro models pusher Bobcat?

Fiberglass should be repairable. I've seen an original Bobcat plow in at high speed and it is now flying again. Which way was your clunk pointed? You may have drawn air if you installed with the clunk forward.
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Old 05-02-2007, 10:08 PM
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Default RE: Nitro models pusher Bobcat?

I crashed mine on its maiden busted the fuse up about the same place u did i fixed it with fiberglass mat and resin on the inside it was a very easy fix it was busted up prety bad now its stronger than before and has 15 or so flights on it dont give up !

Cg on mine and my buddys is 10.5 we flew today with no winds had a blast this is a fun plane

Good luck

Jason
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Old 05-03-2007, 07:54 AM
  #1606
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Default RE: Nitro models pusher Bobcat?

Jason, way to go. Never give up on glass. Use CA to piece together and get everything aligned, reglass from the inside and use lightweight body filler to fill the remaining holes and gaps.
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Old 05-03-2007, 08:05 AM
  #1607
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Default RE: Nitro models pusher Bobcat?

A guy in our club just test flew his. I believe it's the nitro models but not sure. He used an axi outrunner with a 12x10 pattern prop. It has retracts as well. It flew great. It was screaming by at a little over 1/2 throttle. He cranked it up and blew off his canopy Here's a pic
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Old 05-03-2007, 08:40 AM
  #1608
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Default RE: Nitro models pusher Bobcat?

I appreciate everyone's input. The tank is installed as shown on this thread with the outlets facing the front of the airplane, the clunk towards the rear and the fuel lines run around the tank back to the engine. I believe the engine went rich, not lean. When I was doing my break-in runs using a tractor prop to keep it cool, the engine had a tendancy to be quite rich in the mid range while set properly at both low and high range. It would quite often load up and quit at about 1/2 throttle. I had adjusted the low range to a point that I thought I had that situation cured but I guess not. We ran the engine for a short time at low rpm before take-off because we were doing a range check before the first flight. I think the engine crankcase loaded up and simply went way to rich at 1/2 throttle resulting in a flame out shortly after take-off. The fibreglass fuselage is severely broken but probably repairable. However, it probably will never be very attractive again. I wish I could just get a new fuselage from Nitro Planes.

Best wishes and good safe flying.

Heli-NuBee (Roger)
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Old 05-03-2007, 09:58 AM
  #1609
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Default RE: Nitro models pusher Bobcat?

Roger,

Check out this thread for pictures of a rebuilt plane after the fuse was crushed from tip to wing and split in half. Look for the red Bobcat posts 519, 553, 554 & 603. http://www.rcuniverse.com/forum/m_33...21/key_/tm.htm

If you are willing to put in the time you can get these results yourself.

Mark
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Old 05-03-2007, 10:45 AM
  #1610
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Default RE: Nitro models pusher Bobcat?

Check what I received today from Weston-UK for my OS 55AX...
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Old 05-03-2007, 06:46 PM
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Default RE: Nitro models pusher Bobcat?

Quote:
ORIGINAL: Heli-NuBee

I appreciate everyone's input. The tank is installed as shown on this thread with the outlets facing the front of the airplane, the clunk towards the rear and the fuel lines run around the tank back to the engine. I believe the engine went rich, not lean. When I was doing my break-in runs using a tractor prop to keep it cool, the engine had a tendancy to be quite rich in the mid range while set properly at both low and high range. It would quite often load up and quit at about 1/2 throttle. I had adjusted the low range to a point that I thought I had that situation cured but I guess not. We ran the engine for a short time at low rpm before take-off because we were doing a range check before the first flight. I think the engine crankcase loaded up and simply went way to rich at 1/2 throttle resulting in a flame out shortly after take-off. The fibreglass fuselage is severely broken but probably repairable. However, it probably will never be very attractive again. I wish I could just get a new fuselage from Nitro Planes.

Best wishes and good safe flying.

Heli-NuBee (Roger)
Roger,

What prop were you running?

and..you might want to check your low end settings, I have noticed that as far as Idle this engine will accept a wide range of low end needle settings and idle just fine however, you really need to fine tune the low end setting for the transition.

Best of luck, sorry to hear about the crash.

Leighton
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Old 05-03-2007, 07:49 PM
  #1612
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Default RE: Nitro models pusher Bobcat?

I do not own any Tower engines but I have to agree with AGR413. The low speed needle setting will affect the mixture all the way up to wide open. They really should give this needle a new name because it controls much more of the throttle curve than just the idle. If your engine was loading up at half throttle, the low speed needle was most likely way too rich. Kinda curious though why you were only at half throttle for takeoff and climb out.
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Old 05-04-2007, 02:56 AM
  #1613
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Default RE: Nitro models pusher Bobcat?

Quote:
ORIGINAL: Stick Jammer

. Kinda curious though why you were only at half throttle for takeoff and climb out.
I was thinking the same thing, maybe next time line it up and go to full and keep her on the ground for another 1-200 feet. Then you'll know whether if she's too rich to take off. Or have someone hold the nose and give a few throttle up and downs to check responses before launch. Don't be too anxious to fly if you're engine isn't functioning properly. Another 5 minutes on the ground can save dozens of repair hours. We've all been there at one point or another...
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Old 05-04-2007, 10:33 AM
  #1614
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Default RE: Nitro models pusher Bobcat?

Received my replacement canopy in today's mail.

Believe it or not, I got exactly what I ordered...White.

Sorry, P-51MAN

PM
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Old 05-04-2007, 01:12 PM
  #1615
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Default RE: Nitro models pusher Bobcat?




Quote

There are no issues with the gear in the stock position. After flying about hundred flights in the stock gear, I installed retracts in the same positions. issues flying with the stock locations you probably have other issues going on.???????




Guess after reading another post of yours re holding the model on the runway for another 1-200 feet I guess the Issues with myself and most flyer's is that they do not have the luxury of having more than a 200 feet of runway to begin with so that Is why I recommend to reverse the gear location. Then you will be able to rotate after 100 feet or less on a grass strip.

Cheers
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Old 05-04-2007, 01:16 PM
  #1616
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Default RE: Nitro models pusher Bobcat?


Quote:
ORIGINAL: PointMagu

Received my replacement canopy in today's mail.

Believe it or not, I got exactly what I ordered...White.

Sorry, P-51MAN

PM
Thanks anyway !!!
I e-mailed Nitro about them sending me the wrong color, They gave me a RMA number and said to send them back but they didn't say what they would do about it. So I am going to send them back and hope for the best. I don't know if they will refund the shipping cost to send them back even though they made the mistake but we will see.

Thanks again.

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Old 05-04-2007, 01:57 PM
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Default RE: Nitro models pusher Bobcat?

Quote:
ORIGINAL: GSK




Quote

There are no issues with the gear in the stock position. After flying about hundred flights in the stock gear, I installed retracts in the same positions. issues flying with the stock locations you probably have other issues going on.???????




Guess after reading another post of yours re holding the model on the runway for another 1-200 feet I guess the Issues with myself and most flyer's is that they do not have the luxury of having more than a 200 feet of runway to begin with so that Is why I recommend to reverse the gear location. Then you will be able to rotate after 100 feet or less on a grass strip.

Cheers
Cheers,
I was merely suggesting letting a new or troubled engine wind up (and down the runway or strip) for a stretch before taking off that way you may be able to spot trouble before gaining any crash altitude. I didn't think having a 150' runway (1-200 feet) was too much of a luxury anyway but I guess I'm lucky. Model at 0, run down strip to min. 100', rotate...or... 50' runoff room
Don't read too much into that. If you have the stock setup correctly and you're engine is running smooth, there is no reason you can't rotate in 100 feet or less. On the other hand, flying from grass, sounds like your suggestion of reversing the gear may help out with rotation off the weeds.

Beers
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Old 05-04-2007, 05:06 PM
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Default RE: Nitro models pusher Bobcat?

Original: GSK

Quote:
Guess after reading another post of yours re holding the model on the runway for another 1-200 feet I guess the Issues with myself and most flyer's is that they do not have the luxury of having more than a 200 feet of runway to begin with so that Is why I recommend to reverse the gear location. Then you will be able to rotate after 100 feet or less on a grass strip.
I have no doubt that with a good power plant this plane could get off the ground in 100 feet or less but landing it on a 200' strip is tricky to say the least. We have 600' of grass at our field and some people can't set down a trainer. At any rate, 200' is awful short to land most planes.
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Old 05-04-2007, 05:19 PM
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Default RE: Nitro models pusher Bobcat?


Quote:
ORIGINAL: Stick Jammer

Original: GSK

Quote:
Guess after reading another post of yours re holding the model on the runway for another 1-200 feet I guess the Issues with myself and most flyer's is that they do not have the luxury of having more than a 200 feet of runway to begin with so that Is why I recommend to reverse the gear location. Then you will be able to rotate after 100 feet or less on a grass strip.
I have no doubt that with a good power plant this plane could get off the ground in 100 feet or less but landing it on a 200' strip is tricky to say the least. We have 600' of grass at our field and some people can't set down a trainer. At any rate, 200' is awful short to land most planes.
HaHaaHa Yep I guess there are a few around, Our grass strip is 160 feet long and It is Ok for the Bobcat the way I have set it up , comes In slow nose high stops in 50 feet or less from touchdown ,
We are having a working Bee today to lengthen it out another 40 metres,,, mainly because th pattern ships and the large scale ships cannot stop In time
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Old 05-05-2007, 07:32 PM
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Default RE: Nitro models pusher Bobcat?

So has anyone seen the Bobcat with the 'retract ready' option? It costs $10 more, but there isn't much other information on the Nitro Models website. For example, anyone know which retracts it's ready for?
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Old 05-05-2007, 07:40 PM
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Default RE: Nitro models pusher Bobcat?

Anyone know what size bolts attach the booms to the wings..I want to switch the plastic bolts for metal. I know it is between 4 and 6 mm....

Thanks

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Old 05-05-2007, 08:14 PM
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Default RE: Nitro models pusher Bobcat?

They're 4mm. I found some with a phillips head at my local hardware store. Smart move changing to steel.
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Old 05-05-2007, 08:30 PM
  #1623
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Default RE: Nitro models pusher Bobcat?


Quote:
ORIGINAL: robert92679

So has anyone seen the Bobcat with the 'retract ready' option? It costs $10 more, but there isn't much other information on the Nitro Models website. For example, anyone know which retracts it's ready for?

I'd say send 'em an e-mail or call for more info. If the "Retract Ready" version is as poorly built as the fixed gear blocks, it probably ain't worth it.
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Old 05-06-2007, 12:12 AM
  #1624
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Default RE: Nitro models pusher Bobcat?

Quote:
They're 4mm. I found some with a phillips head at my local hardware store. Smart move changing to steel.
thanks SJ, I figured it out, and just finished swapping them out....just waiting for the battery to finish cycling, and a final balance check, and hopefully it will fly tomorrow......


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Old 05-06-2007, 04:45 PM
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Default RE: Nitro models pusher Bobcat?

It Flies !!


Windy as heck today, but it was more or less down the runway. It did the leap-into-the-air thing, so I need to lengthen the nose strut. Got it trimmed out and it flies pretty decently (considering the conditions) Rolls are unbelieveable...!!!! The glow plug let go (we found out later) part way into the flight...resulting in a dead stick landing on rough ground three feet short of the runway.... Guess what?? The stock landing gear blocks held.....the only damage was a slightly bent main gear leg.... Easily bent back at the field (too easily, perhaps....) Noticed a heck of a nose down pitch when the engine quit, though....

Second flight went much better, but still getting a nose down pitch when coming off the power...and running out of up elevator.

Running a 46 FX with an APC 10-8 pusher....did not try any full throttle speed runs due to the wind an turbulence, althoug my son did a horrific dive from about 800' but he had the engine at idle...it was smoking when it came low across the field!!

Got a few things to do before the next flight......




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