BVM BOBCAT setup question
08-26-2016, 02:17 AM
#1
BVM BOBCAT setup question
Bobcat Owners, got a question for you,
I recently picked up a composite bobcat, I set it up with BVs CG (on the little holes in the boom) put about 15 flights on it, and thePlane flies good. I have sold it to a buddy and working on getting him his waiver, and am still helping get it just right. Since I have never owned a bocat or the likes I am not sure about setting up the optimal CG. The engine is a P70 and it has some down thrust in it, two #2 washers under the front of the engine mount. The jet flies great, and lands great, nice and slow nose up, but the one thing I notice is when inverted it takes a good amount of elevator to Hold it level, Normally that's the sign of a nose heavy setup, but this one having the engine down thrust is what is confusing me. Any Bobcat Pilots with insight on this I would appreciate it, I can move some batteries back, but just want to see if this is normal for this jet
Thanks Fellas
I recently picked up a composite bobcat, I set it up with BVs CG (on the little holes in the boom) put about 15 flights on it, and thePlane flies good. I have sold it to a buddy and working on getting him his waiver, and am still helping get it just right. Since I have never owned a bocat or the likes I am not sure about setting up the optimal CG. The engine is a P70 and it has some down thrust in it, two #2 washers under the front of the engine mount. The jet flies great, and lands great, nice and slow nose up, but the one thing I notice is when inverted it takes a good amount of elevator to Hold it level, Normally that's the sign of a nose heavy setup, but this one having the engine down thrust is what is confusing me. Any Bobcat Pilots with insight on this I would appreciate it, I can move some batteries back, but just want to see if this is normal for this jet
Thanks Fellas
08-26-2016, 02:50 AM
#2
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Bobcat Owners, got a question for you,
I recently picked up a composite bobcat, I set it up with BVs CG (on the little holes in the boom) put about 15 flights on it, and thePlane flies good. I have sold it to a buddy and working on getting him his waiver, and am still helping get it just right. Since I have never owned a bocat or the likes I am not sure about setting up the optimal CG. The engine is a P70 and it has some down thrust in it, two #2 washers under the front of the engine mount. The jet flies great, and lands great, nice and slow nose up, but the one thing I notice is when inverted it takes a good amount of elevator to Hold it level, Normally that's the sign of a nose heavy setup, but this one having the engine down thrust is what is confusing me. Any Bobcat Pilots with insight on this I would appreciate it, I can move some batteries back, but just want to see if this is normal for this jet
Thanks Fellas
I recently picked up a composite bobcat, I set it up with BVs CG (on the little holes in the boom) put about 15 flights on it, and thePlane flies good. I have sold it to a buddy and working on getting him his waiver, and am still helping get it just right. Since I have never owned a bocat or the likes I am not sure about setting up the optimal CG. The engine is a P70 and it has some down thrust in it, two #2 washers under the front of the engine mount. The jet flies great, and lands great, nice and slow nose up, but the one thing I notice is when inverted it takes a good amount of elevator to Hold it level, Normally that's the sign of a nose heavy setup, but this one having the engine down thrust is what is confusing me. Any Bobcat Pilots with insight on this I would appreciate it, I can move some batteries back, but just want to see if this is normal for this jet
Thanks Fellas
J
08-26-2016, 10:20 PM
#4
Good thread as I'm trying to work out the CG issue on my bobcat with a P100. My plane is set up about 1/4" behind the CG holes under the booms but the plane still feels nose heavy. My main problem is when I'm coming in for landing and as soon as I go to idle the plane nose dives abruptly. I have up trim with landing flap and am using a bit of crow. I'm thinking that the plane is still very nose heavy. I'll move CG aft a bit more and see how it handles on the landing.
04-18-2017, 06:19 AM
#6
Join Date: May 2015
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CG and thrustline help for Orginal Bobcat
I bought a used Bobcat last year and still haven't flown it (no manual... can someone supply me one?). I'm the 3rd owner. The 1st looks to be RCPete.
I've read everything I could on setting up the Bobcat. It's funny that the bvm site does not mention weather the setup settings apply to the balsa Bobcat too. This is an older one (balsa with no CG holes). Most references mention the newer composite version. The CG has me perplexed. I drilled holes 9-3/4 from the front of the boom and find the CG is a good 30mm forward (6oz header full, gear down). I had to move all 3 batteries to the behind the canopy latch (about 16 inches) to get the CG 10mm aft of factory. Previously, the batts were under where the pilot would sit. I'm running an older Rabbit... ~P100.
Does anyone else have their batteries located the same? I'm wondering if the composite and the balsa are different animals with different CGs. I do like aft CG with my models... I like the response and I believe it puts less load on the servos.
Also, I've read that the thrust line should be parallel to the aft fuse top. If true, my the thrust line looks to be about half that amount.
This is the freshest thread I could find. I hope someone sees this and can render some help. - Thanks
I've read everything I could on setting up the Bobcat. It's funny that the bvm site does not mention weather the setup settings apply to the balsa Bobcat too. This is an older one (balsa with no CG holes). Most references mention the newer composite version. The CG has me perplexed. I drilled holes 9-3/4 from the front of the boom and find the CG is a good 30mm forward (6oz header full, gear down). I had to move all 3 batteries to the behind the canopy latch (about 16 inches) to get the CG 10mm aft of factory. Previously, the batts were under where the pilot would sit. I'm running an older Rabbit... ~P100.
Does anyone else have their batteries located the same? I'm wondering if the composite and the balsa are different animals with different CGs. I do like aft CG with my models... I like the response and I believe it puts less load on the servos.
Also, I've read that the thrust line should be parallel to the aft fuse top. If true, my the thrust line looks to be about half that amount.
This is the freshest thread I could find. I hope someone sees this and can render some help. - Thanks
04-18-2017, 06:13 PM
#7
My Feedback: (1)
I bought a used Bobcat last year and still haven't flown it (no manual... can someone supply me one?). I'm the 3rd owner. The 1st looks to be RCPete.
I've read everything I could on setting up the Bobcat. It's funny that the bvm site does not mention weather the setup settings apply to the balsa Bobcat too. This is an older one (balsa with no CG holes). Most references mention the newer composite version. The CG has me perplexed. I drilled holes 9-3/4 from the front of the boom and find the CG is a good 30mm forward (6oz header full, gear down). I had to move all 3 batteries to the behind the canopy latch (about 16 inches) to get the CG 10mm aft of factory. Previously, the batts were under where the pilot would sit. I'm running an older Rabbit... ~P100.
Does anyone else have their batteries located the same? I'm wondering if the composite and the balsa are different animals with different CGs. I do like aft CG with my models... I like the response and I believe it puts less load on the servos.
Also, I've read that the thrust line should be parallel to the aft fuse top. If true, my the thrust line looks to be about half that amount.
This is the freshest thread I could find. I hope someone sees this and can render some help. - Thanks
I've read everything I could on setting up the Bobcat. It's funny that the bvm site does not mention weather the setup settings apply to the balsa Bobcat too. This is an older one (balsa with no CG holes). Most references mention the newer composite version. The CG has me perplexed. I drilled holes 9-3/4 from the front of the boom and find the CG is a good 30mm forward (6oz header full, gear down). I had to move all 3 batteries to the behind the canopy latch (about 16 inches) to get the CG 10mm aft of factory. Previously, the batts were under where the pilot would sit. I'm running an older Rabbit... ~P100.
Does anyone else have their batteries located the same? I'm wondering if the composite and the balsa are different animals with different CGs. I do like aft CG with my models... I like the response and I believe it puts less load on the servos.
Also, I've read that the thrust line should be parallel to the aft fuse top. If true, my the thrust line looks to be about half that amount.
This is the freshest thread I could find. I hope someone sees this and can render some help. - Thanks
04-19-2017, 06:26 AM
#8
Join Date: May 2015
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Kelly, Found it! Thanks for pointing that out. For any other newbies, the newer composite and the early balsa bobcats have big differences in their setups. i.e. there is a 25mm difference in the cg location.. which was my problem. I moved all batteries back the original location and it cgs 10mm back from the factory 8.7 inch (from the front of the boom) location. I'll keep it there until I've logged my 1st flights.
Concerning the thrust-line, I was looking a many pics of guys with their bobcats and it looks like there thrust-line is about the same as mine so I keep it there and see how it goes.
Concerning the thrust-line, I was looking a many pics of guys with their bobcats and it looks like there thrust-line is about the same as mine so I keep it there and see how it goes.
07-20-2017, 05:26 AM
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As a follow-up to my last post, I've logged 26 flights. I find that trying to do a missed approach or touch-n go, that the plane wants to pitch down... to the point that in some cases the wheels actually touched before my turbine spooled up. Mine takes about 5 sec from idle.. it's actually an older VT-90 JC. My CG is 13mm back from factory and I have all the elev I can get but still about 1/4' shy of factory high rate. However, I think the main cuplrit is the thrust line. When going slower <100 mph, I have to hold a bit of up elevator but when > 150, she flies level. I think I'm gonna try adding a washer to the aft turbine mount to reduce the thrust angle. My understanding from the posts above is that this will cause a pitch up on power up at slower speeds (due to increased low pressure at the bottom side of the tailplane)
