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Nitro models pusher Bobcat?

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Old 10-23-2007, 09:24 AM
  #2451
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Default RE: Nitro models pusher Bobcat?


Quote:
ORIGINAL: opjose

Beautiful!

Good luck!
Quote:
ORIGINAL: cngaviation

I see. You sure did a nice job on everything. Good luck this weekend.

Thanks guys.. I just hope the weather is ok. Does not look too good but it is early yet.....
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Old 10-23-2007, 09:53 AM
  #2452
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Default RE: Nitro models pusher Bobcat?

Blue - Nice! I love the Shark Teeth!!!!

Looks like a nice retract install, too.

On the retract-ready version, the front wheel has about 1/4 of the wheel still in the airstream because of the flush mount. I don't think it makes that big of a difference in performance, but I gues with the same "everything" yours will be a bit "slippy-er".

Don't let the weather bother you. As long as it's not raining - go fly it. It cuts through the wind easily, and if you have wind coming down the runway, you can really float it in slowly. Set up the spoilerons - you'll be happy with them for landing. They should go up no more than 1/4" max - that is all you need, and it will settle in nicely for nose-high landings.

* * *
I'm going to hook up my onboard video camera this weekend I think, and get some cool video. I'm not yet sure where to mount the camera yet. Any ideas guys? I got it for my heli, but I haven't yet flown with it yet, so I think I'd rather have it on something that will show the speed. (I already know what my neighborhood looks like from above...).

Cya
Mark
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Old 10-23-2007, 10:20 AM
  #2453
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Default RE: Nitro models pusher Bobcat?

Quote:
ORIGINAL: marktur

Blue - Nice! I love the Shark Teeth!!!!

Looks like a nice retract install, too.

On the retract-ready version, the front wheel has about 1/4 of the wheel still in the airstream because of the flush mount. I don't think it makes that big of a difference in performance, but I gues with the same "everything" yours will be a bit "slippy-er".

Don't let the weather bother you. As long as it's not raining - go fly it. It cuts through the wind easily, and if you have wind coming down the runway, you can really float it in slowly. Set up the spoilerons - you'll be happy with them for landing. They should go up no more than 1/4" max - that is all you need, and it will settle in nicely for nose-high landings.

Cya
Mark
Thanks Mark.
I had some decals laying around so I thought I would use some of those as the ones with the plane just didn't seem right. I thought the shark's teeth would look cool on this plane and it came out pretty good. Little tough to line up and took some time but she came out ok.

This was my first attempt at installing retracts and I had plenty of help with advice and pictures from this thread. I originally had problems with the fixed gear blocks coming loose and thought if I had to cut it open I mind as well try adding retracts. Took me a long while and I kept asking myself why I made this into a project, but watching them go up and down at the flip of a switch has made it all worth it. We have about 4 to 5 Bobacats at our field now and mine will be the first with retracts. So it will be interesting to see if there is any noticeable difference.

Although you don't really see it in the pictures, my nose gear will sit down about a 1/4 of an inch below the fuse just like the retract ready version. I think it is due to mounting it on the firewall around the same spot as the nylon piece for the fixed nose gear.

They are calling for a chance of rain this weekend. Hopefully it is just that a chance. I did hook up spoilers as you guys suggested. I adjusted them to a 1/4 of an inch and they are mixed with my throttle. The spoilers go up as the throttle goes down.

Bill
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Old 10-23-2007, 01:09 PM
  #2454
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Default RE: Nitro models pusher Bobcat?

Bill - I wouldn't like spoilers and throttle tied in personally. I like to fly around slowly sometimes to show off the wide range of speed...spoilers + flying slow - not landing don't seem like fun...I can imagine having to hold elevator would not be fun after a while. I'm using a Spektrum heli radio, and I put the spoilers on the Idle up switch (3-position) and I use it as normal, 50% spoiler, 100% spoiler. Much easier to deploy than using a knob IMHO.

I think you'll see a speed difference, but you've raised the "cool factor" at the field in a big way. I'll bet 4 out of 5 guys drop in retracts after they see yours...it's just too cool! I need to slow mine down a bit...they slam shut and open. It's personal preference, but I was watching my buddies plane the other day, and it looks cool going slower (more scale-like).

Good luck on the flight - post some video!

Mark
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Old 10-23-2007, 07:04 PM
  #2455
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Default RE: Nitro models pusher Bobcat?

Xairflyer,
I put together one of the initial versions before they offered the retract ready flavor. I recently ordered one of the latest retract ready versions because I just couldn't pass it up for 105 bucks. I haven't started building the latest one but the wings are not the same as my original. The wings of the retract ready version are quite a bit thicker with a thicker leading edge. The thinner wing should fly a bit faster but the thicker wing allows a little more room for the retracts. I would think the thicker wing will also slow down a bit faster on final which might be a good thing for grass fields. They have also relocated the main gear location farther out from the fuse and the aileron servo bays are farther out as well. The wider wheelbase should be more stable for ground turning as the original tips onto a wing pretty easy. Not a big deal on grass but pavement is a little rough on the wing tips.
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Old 10-24-2007, 05:34 AM
  #2456
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Default RE: Nitro models pusher Bobcat?

Thanks for that Jammer, the thicker wing would help it fly slower OK, my supplier is out of stock of the retract ready version so just have to get the standard one again.
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Old 10-24-2007, 10:22 PM
  #2457
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Default RE: Nitro models pusher Bobcat?

Original: marktur

Quote:
I'm going to hook up my onboard video camera this weekend I think, and get some cool video. I'm not yet sure where to mount the camera yet. Any ideas guys? I got it for my heli, but I haven't yet flown with it yet, so I think I'd rather have it on something that will show the speed.
Don't know what your camera setup weighs but right on the bottom of the fuse at the CG is the best spot. Facing forward should capture some pretty good video coming out of dives and low passes. I recently ordered one of the new FlyCamOne digital video and audio units from Hobby Lobby. I took some video with it strapped onto my Somethin' Extra and it works very well, the video is suprisingly clear and smooth. It's only 3"x 1 3/4"x 1/2" and weighs just an ounce. Has its own internal lithium battery and takes an SD card for recording. A one Gig card holds an hour of video, pretty cool.
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Old 10-25-2007, 12:10 AM
  #2458
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Default RE: Nitro models pusher Bobcat?

I have seen entries about the little .25 bobcat too. we maidened mine last week with fixed gear, pretty much stock build. It required alot of emprovision as the quality isn't the best but got er done. I mounted the ESC under the belly outside the plane..., and cut a motor notch out of the back of the fuse, so the thrust line is down the belly, with about 2 degrees down thrust.

It has a medusa 2500KV and a 6S A123 power system with a 6x4 prop doing close to 1000 watts. Its so damm fast, and small. gets your blood goin. best guess close to 100. Flying it a little nose heavy with no problem. Yes I said 1000 watts, 31,000 rpm. ITs amazing. thats why the controller is under the belly for cooling. I also put a scoop in the belly for battery cooling, and the medusa has cooling fins. I enlarged the hole in the back of the fuse too. HOly smokes this thing goes.!!!! I think you could launch it by hand.

the only thing I dont like is that it is a little unstable in roll, just a bit wobbly. I used all MG servos for flutter since we are pushing the airframe alot faster than designed.

spoilers 1/2 inch is a must for landing, it settles it right down. I think I need just a couple more degrees downthrust, otherwise ok.
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Old 10-25-2007, 11:55 AM
  #2459
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Default RE: Nitro models pusher Bobcat?

Damn!

I'm up to 890 Watts with a 6S LiPo setup, but I'm using a relatively low KV motor, so I'm *****g out at 16-18K RPMs with a 9x7.5 prop.

The plane moves well, but I don't think it has a CHANCE of keeping up with yours.

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Old 10-26-2007, 02:55 PM
  #2460
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Default RE: Nitro models pusher Bobcat?

Hey wasn't there about 115 pages to this thread before? I could have sworn that we were way over 110...
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Old 10-26-2007, 03:23 PM
  #2461
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Default RE: Nitro models pusher Bobcat?


Someone had the "urge to purge".

It was indeed longer.

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Old 10-26-2007, 08:50 PM
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Default RE: Nitro models pusher Bobcat?

THe little medusa on the falcon25 was screamin today. we got 1000 watts at 73 amps on the 6x4 prop and flew it today. the A123's are 2300 mah. after a five min flight the cutoff kicked in at 12 volts. Sure am glad I installed a UBEC on the aircraft...

WHen I checked the voltage it was down around 15 which is 2.5 volts per cell. that is on the backside of the A123 curve.

When I recharged it took 2296mah. so we pushed it right to the edge. Even the A123's were quite warm, and the wiring was warm too. My guess with dynamic loading we may have been pushing over 100 amps on burst.

I changed to a 5.5x4.5 and dropped it 10 amps, and the flight time went to 7 minutes, and am guessing we maybe lost 5mph, and a little static thrust, but its over powered anyway. AGain best guess was about 95 mph or so with fixed gear. amazed alot of folks today. the little medusa rocks. what a great trainer for a turbine swept wing. Oh an must use reflex to get it to slow down.

If I had to do it again, I would get a 2200 kv motor and swing a 7x5 prop trying to achieve about 28000rpm. The A123's depress a little more than lipos, but are flatter. the 6S pack at 70 amps was delivering 14 volts or 2.35 volts per cell under load. by lightning the load a bit and spinning the prop faster, we didnt really lose any top end. it still took off in 30 feet.

Just thought you electric bubbas might like this story. we got 6-7 min flights just like the turbine bubbas today. They liked it!!
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Old 10-27-2007, 07:31 PM
  #2463
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Default RE: Nitro models pusher Bobcat?

Question for the turbine conversion guys. What weight did yours come out to? Mine with a JetJoe 1200 is 11 pounds. Hope to fly it tommorrow if all goes well.
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Old 10-27-2007, 08:45 PM
  #2464
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Default RE: Nitro models pusher Bobcat?

Yours seems heavy at 11lbs have you also fitted retracts ?
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Old 10-27-2007, 08:55 PM
  #2465
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Default RE: Nitro models pusher Bobcat?

Sorry reweighed it 10.5 pounds no retracts but full autostart. Could have saved half pound with semi auto ECU.
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Old 10-27-2007, 10:04 PM
  #2466
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Default RE: Nitro models pusher Bobcat?

Mine came in at 10.3 lbs with retracts, flaps, full auto start and brakes
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Old 10-27-2007, 11:41 PM
  #2467
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Default RE: Nitro models pusher Bobcat?

Man, I'm so ticked off - went to fly fly my Bobcat today, and after 3 great flights with an OS 55, my canopy decided to do a lift and separate. The back half of the canopy was still there, acting as a speed brake - made for an exciting landing. Made it down - the plane if OK, but now I only have half a canopy. I've patched together a canopy by combining what I have left with half of a canopy from my old AV8R - looks like hell, but it will fly Sunday.

I need another, but looks like the only way I can get one is to buy another kit - and I really would rather have the Falcon 120, so I can have a home for my Ram T-500.

I'm tempted to put my Ramtec Fan on the thing with a K & B 7.5 - this combo works fairly well on my old tired (heavy) Enforcer, should work great on this plane with less weight.

Mark
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Old 10-28-2007, 07:52 AM
  #2468
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Default RE: Nitro models pusher Bobcat?

NM MARK

THEY HAVE CANOPIES, GO TO THE WEBSITE, DO A SITE SEARCH (TOP LEFTHAND CORNER) TYPE IN CANOPY THEN GO TO PAGE FIVE. $7.00 EACH. SHIPPING ???
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Old 10-28-2007, 07:58 AM
  #2469
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Default RE: Nitro models pusher Bobcat?

They seem heavy mine was only 9lb 2ozs with full auto apart from the gas can which weighs nothing, I still have the valves, regulator and a metal check valve for filling the gas. Wonder where your weight has came from. I had a 7.4v 1850mah lipo for ecu and 1400mah pack for radio.
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Old 10-28-2007, 09:24 AM
  #2470
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Default RE: Nitro models pusher Bobcat?

Well, got my Bobcat all back together after the safety fence mishap. Made a couple of changes while it was apart. Made the tail boom inner servo bays larger to accept standard size servos and went with a single HS-475HB on elevator and a single for rudders. Made up a carbon fiber tie rod with ball links to couple the rudders together. Much easier (and cheaper) setup than four tail servos and the weight stayed the same. Plus I prefer the durability of standard size servos over the mini's. I also added an exhaust deflector to my homemade muffler extension which points directly rearward now. My initial setup with just the muffler extension created quite a mess in flight, hopefully this will be better.
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Old 10-28-2007, 09:52 AM
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Default RE: Nitro models pusher Bobcat?


Quote:
ORIGINAL: Stick Jammer

Well, got my Bobcat all back together after the safety fence mishap. Made a couple of changes while it was apart. Made the tail boom inner servo bays larger to accept standard size servos and went with a single HS-475HB on elevator and a single for rudders. Made up a carbon fiber tie rod with ball links to couple the rudders together. Much easier (and cheaper) setup than four tail servos and the weight stayed the same. Plus I prefer the durability of standard size servos over the mini's. I also added an exhaust deflector to my homemade muffler extension which points directly rearward now. My initial setup with just the muffler extension created quite a mess in flight, hopefully this will be better.

Do you have enough room under that rod for the rudders to start the plane safely? Looks a little tight.
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Old 10-28-2007, 09:07 PM
  #2472
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Default RE: Nitro models pusher Bobcat?

Maidened mine Bobcat with JetJoe 1200 even at over 11 pounds take off weight flew very well and plenty of power. Think I need to put it on a diet and get some weight out of it could save a bunch by going to a lipo for ecu and 1 5 cell radio battery instead of 2 4 cell packs. Very happy with the plane and engine.
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Old 10-28-2007, 09:16 PM
  #2473
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Default RE: Nitro models pusher Bobcat?

Been thinking about doing that same set-up with the manual start and retracts. Would love to see some video to see how fast she is on the 1200.

Thanks,

Brian
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Old 10-28-2007, 09:18 PM
  #2474
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Default RE: Nitro models pusher Bobcat?

Glad it went well, any pics
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Old 10-28-2007, 09:42 PM
  #2475
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Default RE: Nitro models pusher Bobcat?

Had another club member taking in flight pics but thet didn't turn out very well. Another club member has one with a 60 pusher and mine was faster just tooling around at 2/3 throttle than his was flat out. clean it up with retracts and a little less weight this plane would be plenty fast. Wouldn't want to push this airframe too far.
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