RE: Nitro models pusher Bobcat?
Thanks Bills,,,,I'm really looking forward to the maiden flight. I hope the top speed will be over 100+.....will let all know results.
lots of family in greensboro...I grew up just outside of greensboro so I know the area really well..... |
RE: Nitro models pusher Bobcat?
GRAMS one of the older clubs in the area moved to a new field about a year ago. The flight field is on City/County park property and is located in Brown Summit. Miracles never cease. Maybe you can visit sometime.
Bill |
RE: Nitro models pusher Bobcat?
I do,,,,my brother, sisters and dad live there...so I try to come back once a year or so.
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RE: Nitro models pusher Bobcat?
Looks like I am going to end up slightly tail heavy. Anyone experimented with moving the tail feathers forward an inch or so?
Bill |
RE: Nitro models pusher Bobcat?
How much is "slightly"?
Up to .75" is not going to have an adverse effect on the plane, and may even improve landings and rotations... however you may want to add a bit more expo to your rates to offset any increases in sensitivity. |
RE: Nitro models pusher Bobcat?
ORIGINAL: BillS Looks like I am going to end up slightly tail heavy. Anyone experimented with moving the tail feathers forward an inch or so? Bill A little lead in the nose is much easier and won't add enough to the AUW to matter. ;) |
RE: Nitro models pusher Bobcat?
How much is "slightly"? Today was balance day. The stock Bob Cat without retracts needs 4 oz. of nose weight. It has a .45 engine. The sheeted/painted Bob Cat weights 2 pounds more and is very tail heavy even without engine. It needs 11 oz. to balance w/o engine and 15 oz to balance with a .45 engine. A .45 is probably not enough engine. Bill |
RE: Nitro models pusher Bobcat?
Bill,
Been reading your posts, I'm surprised that your turbine bobcat is tail heavy. I sheeted mine, wings and stab, and it was still nose heavy. I ended up puting both the radio/servo battery and ecu batteries as far back as I could to get ut to balance at 10.3". After about 1.5oz added to the tail. Flys fine just had to decrease the ailerons and add a bunch of expo to smooth it out. What Size turbine are you using? Hapyjac www.SouthFloridaJetTogether.com |
RE: Nitro models pusher Bobcat?
Original: BillS
The stock Bob Cat without retracts needs 4 oz. of nose weight. It has a .45 engine. Wow, that seems odd. Mine is stock, OS 55AX with stock muffler, fixed gear, 5-cell battery just behind the nose gear former and I only needed 1/4 ounce in the nose for 10.3" CG. |
RE: Nitro models pusher Bobcat?
I have just started to work on my new bobcat 25.I am mounting a Lambert micro turbine and I wanted to know if there was a certain thrust angle that you guys were putting the turbine at .I know you guys are using the wren 44 on the bigger bobcat so I figure I would do it the same way as you guys are and should be good.
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RE: Nitro models pusher Bobcat?
What Size turbine are you using? As a rough check the airplane was put in the balance cradle without engine and it needed 11 oz on the nose to get the CG correct. An additional 1/3 of the engine weight will be required in the nose to maintain CG. This project is experimental and likely headed towards a prop engine. Bill |
RE: Nitro models pusher Bobcat?
ORIGINAL: BillS Based on the bare weight, wing area and landing description it is easy to believe the landing speed was over 40 mph. Did he have brakes in it? |
RE: Nitro models pusher Bobcat?
Hey Guys,
Anyone know what RPM boost the Genesis pusher pipe for the Bobcat will give for a Magnum 52 engine. Would like to know what to expect from someone who has used them. thanks |
RE: Nitro models pusher Bobcat?
Original: BillS
This project is experimental and likely headed towards a prop engine. Might be a good candidate for doing away with the tail feathers completely and fly it with elevons. I don't recall anyone trying this but yours seems well suited due to the excess tail weight. It's basically a delta wing and it should work considering how pitch sensitive the airframe is to spoilerons and flaperons. In it's present state it sounds like you're gonna need more power than a glow engine can produce as prop size is limited. |
RE: Nitro models pusher Bobcat?
5 degrees downthrust on the turbine version is about right.
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RE: Nitro models pusher Bobcat?
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ORIGINAL: opjose ORIGINAL: BillS Based on the bare weight, wing area and landing description it is easy to believe the landing speed was over 40 mph. Did he have brakes in it? The pictures below show a fixed brake solution to long roll outs. The Bob Cat has not been flown but the brake solution is being used on 4 other airplanes. Bill |
RE: Nitro models pusher Bobcat?
BillS,,,,that looks like a good fix, but I don't think it will work with retracts...The wheel well isn't deep enough to accomadate the rubber...Other than that, it look good.
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RE: Nitro models pusher Bobcat?
ORIGINAL: Meekskin BillS,,,,that looks like a good fix, but I don't think it will work with retracts...The wheel well isn't deep enough to accomadate the rubber...Other than that, it look good. Bill |
RE: Nitro models pusher Bobcat?
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ORIGINAL: Stick Jammer Original: BillS This project is experimental and likely headed towards a prop engine. Might be a good candidate for doing away with the tail feathers completely and fly it with elevons. I don't recall anyone trying this but yours seems well suited due to the excess tail weight. It's basically a delta wing and it should work considering how pitch sensitive the airframe is to spoilerons and flaperons. In it's present state it sounds like you're gonna need more power than a glow engine can produce as prop size is limited. I have an older ST 90 (removable front housing and hope it will run backwards) and a 12 x 8 three blade prop laying on the bench for consideration. It will probably fly with the .90 but minimum flying speed is likely to be in the mid 30's. Your delta suggestion is interesting. The tail section weights 1 pound 7 oz or so with servos. Maybe the delta suggestion can be tested with the skinny Bob Cat first since I have zero delta experience. What is really needed is more wing area. All recent military aircraft have supplemental wing area in front of the main delta wing. The cardboard mockup below of additional wing area might be easy to try. It also might not work. This type of conversation often results in serious breakage. The heavy airplane is simply too pretty to retire. Bill |
RE: Nitro models pusher Bobcat?
would Robart 521w1 work on this baby. Looking to get another for retracts.
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RE: Nitro models pusher Bobcat?
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RE: Nitro models pusher Bobcat?
ORIGINAL: patzane would Robart 521w1 work on this baby. Looking to get another for retracts. I think the retract ready Bobcat is set up for rail mount nose gear, the 521W1's have a firewall mount. The 520W1's have the rail mount. |
RE: Nitro models pusher Bobcat?
Original: BillS
Your delta suggestion is interesting. The tail section weights 1 pound 7 oz or so with servos. Maybe the delta suggestion can be tested with the skinny Bob Cat first since I have zero delta experience. As long as the plane balances at 10.3" with the tail section removed (engine mounted and ready to fly of course) I see no reason why it wouldn't fly. Elevons are just a matter of radio programming. With any experimental test there's always a risk but your "GlassCat" is already going to be an experiment with a glow engine simply due to the weight. On the maiden flight of mine I had about 1/4" of spoilerons programmed in for landing and the test deployment at low speed (with altitude of course) nearly put the plane vertical and probably would have completed a loop if I hadn't clicked them off. There's no doubt in my mind this plane would fly without the elevator. |
RE: Nitro models pusher Bobcat?
I'm looking for a plane to do my 50 required logged flights, as part of my turbine waiver. A guy in my club just put one of these together with retacts, and a OS 61 (I'm not sure which model) and has offered it for sale. Is this thing capable of 100mph?
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RE: Nitro models pusher Bobcat?
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I will let you know next wednesday. My radar gun will be here tuesday and we will be checking the speed on 3 different Bobcat 52. This is a picture of mine with a Magnum 52, Weston Genesis pipe and retracts.
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