RE: Nitro models pusher Bobcat?  
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    • All Forums >> RC Airplanes >> RC Jets >> RE: Nitro models pusher Bobcat?
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    RE: Nitro models pusher Bobcat? - 9/13/2008 12:12:47 PM   
    cyborg1


     

    Posts: 61
    Joined: 11/24/2005
    From: Bangkok, THAILAND
    Status: offline     		brought my bobcat out to the field today, but didn't get any flights in due to windy conditions. not going to risk bungling it again in a crosswind. anyway, got a tachometer ready today. on a tt .50 heli engine with macs tuned pipe, my apc 11x6 pusher was turning about 14000 rpm on ground, not fully peaked on the the rich side. i changed to an apc 10x7 pusher, and the revs went up to 15000, not fully peaked either. sounds great, i'll have to try the 10x7 pusher tomorrow if the weather allows. it should hopefully be faster than the 11x6, as i'd like to get more speed out of it.

    (in reply to opjose)
           Post #: 3451

    RE: Nitro models pusher Bobcat? - 9/13/2008 12:47:50 PM   
    Jeremy_D



    Posts: 472
    Joined: 2/17/2005
    From: Central Coast, AUSTRALIA
    Status: offline     		Looks great John!! You taking it to Temora?

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    www.aussiejet.com

    (in reply to opjose)
           Post #: 3452

    RE: Nitro models pusher Bobcat? - 9/13/2008 4:41:41 PM   
    BillS


     

    Posts: 3077
    Joined: 9/6/2004
    From: Greensboro, NC, USA
    Status: offline     		Other than the “standard servo” statement and what appears to be an engine mount the airplane appears to be the same as the one discussed in this thread.

    The minimum all up weight is likely to be 7 1/2 to 8 lbs and require some up front balance weight. Some all up weight reports in this thread are up to 10 lbs.

    Wing removal and engine size and many other issues are thoroughly covered in this thread, which is worthwhile reading.

    Bill

    (in reply to Rod Robbins)
           Post #: 3453

    RE: Nitro models pusher Bobcat? - 9/13/2008 5:06:06 PM   
    Rod Robbins


     

    Posts: 81
    Joined: 3/25/2002
    From: Beaverton, OR, USA
    Status: offline
    quote:

    ORIGINAL: bob092

    I don't recommend wing removal. It is more of a pain than worth to feed everything through for reassembly. Some of the later planes actually have bolts to align the wings and hold in place , but directions still recommend attaching permenant. I found a set of Wing Mfg. electric retracts that fit mine pretty good so I placed Dean connectors to be able take the wings off but in flight they seem to seperate a little and cause a slight pitch. Its still able to be controled but afixing mine permenantly. The electric seems a nice way to go if you want to try removing them...no servos to be connected or messed with. WWW.sonicelectric.com has a model DSR46C-A that looks like it will work without much problems. The A stands for Aluminum on the struts which increases the weight that can be handled. The plastic ones will dold 4-6 pounds which is to light so if considering be sure to get the aluminum ones. They are supposedly good for up to 10 lbs from the one site i was checking but others drop the weight to 9 lbs. still within specs.
    You hadn't specified if going with fixed or retracts so I threw this in to help confuse you a little more....lol...good luck.


    Thanks, Bob...

    My Bobcat 50 version has fixed landing gear so that simplifies things. Also, I'll probably rethink the wing removal idea, since it looks like it requires removal and replacement of elevator linkages, etc.

    Looks like this will be an interesting project...

    Regards,
    Rod



    _____________________________

    Rod Robbins
    Beaverton, OR U.S.A.

    (in reply to bob092)
           Post #: 3454

    RE: Nitro models pusher Bobcat? - 9/13/2008 5:23:16 PM   
    Rod Robbins


     

    Posts: 81
    Joined: 3/25/2002
    From: Beaverton, OR, USA
    Status: offline
    quote:

    ORIGINAL: Rod Robbins

    Did you find that the stock engine mount was strong enough to handle the power of the .76 ?


    Check my gallery for how I mounted it.

    I DID use the provided wood blocks but I ground down the fiberglass a bit over the hardwood to make the GMS fit with the same thrust line as a smaller engine.

    The provided blocks are a little soft, so I soaked them in CA ( merely because I was lazy... )... I'd recommend replacing them with something else.

    The underlying wood area where the engine mounts is VERY strong...


    Great info... I found your gallery photos on how you made the GMS .76 fit. I've got a Dremel, so that part will be pretty easy.

    quote:


    I just build a small PVC stand to transport my Bobcat at an angle... I epoxied the wings in place... far less hassle and with the stand I can put other planes in my wife's old van ( which I was going to get rid of some time ago and I ended taking out all but the very front seats, and turning it to the "plane mobile"...)


    What a great idea! PVC tubing is kind of like duct tape, i.e. essential for human survival in today's world. I've got the same kind of van situation as you. I long ago removed all the rear seats from my '03 Windstar and it's become my full time airplane hauler. I've already built a sort of "over / under" rack out of PVC and steel tubing for stacking wings & fuselages separately. I can get four .60 size planes and all the support gear in comfortably. The special rack for the Bobcat will fit nicely into the lower deck, I'm sure.


    quote:

    Strengthen & re-inforce the retract mounting areas.
    sand flat the fuse where the wings attach,
    make sure the Bobcat sits slightly nose high with a positive AOA,
    DO use a spoileron mix,
    make sure that you leave long enough extension wires in the wings so you'll be able to remove/replace a servo w/o having to fish new wires through, which is almost impossible,


    All suggestions appreciated. I'll print out this page and have it with me in the shop.

    Thanks again for sharing your experiences.

    Regards,
    Rod



    _____________________________

    Rod Robbins
    Beaverton, OR U.S.A.

    (in reply to opjose)
           Post #: 3455

    RE: Nitro models pusher Bobcat? - 9/13/2008 5:45:11 PM   
    Rod Robbins


     

    Posts: 81
    Joined: 3/25/2002
    From: Beaverton, OR, USA
    Status: offline
    quote:

    ORIGINAL: BillS

    Other than the “standard servo” statement and what appears to be an engine mount the airplane appears to be the same as the one discussed in this thread.

    The minimum all up weight is likely to be 7 1/2 to 8 lbs and require some up front balance weight. Some all up weight reports in this thread are up to 10 lbs.

    Wing removal and engine size and many other issues are thoroughly covered in this thread, which is worthwhile reading.

    Bill



    Hi Bill,

    Thanks for the reply. I've been trying to use the "Search this Thread" function at the bottom of the page and don't come up with too much. For example, if I search on "wing removal", I only get 7 hits, including your post above.

    Maybe I'm just not using the right search phrase. If I search on "engine", I get "The system could not find any record.", which is impossible given that your own post contains the word "engine". Can you give me some suggestions on search words and phrases?

    I also tried to find this info manually. This thread is a gold mine of Bobcat info, but after scrolling and skimming 20 or 30 pages, my eyes start to glaze over.

    Regards,
    Rod



    _____________________________

    Rod Robbins
    Beaverton, OR U.S.A.

    (in reply to BillS)
           Post #: 3456

    RE: Nitro models pusher Bobcat? - 9/13/2008 6:52:50 PM   
    opjose



    Posts: 6145
    Joined: 11/26/2005
    From: Poolesville, MD, USA
    Status: online
    quote:

    ORIGINAL: cyborg1

    I've found that using a heli engine with the increased head area works great for pushers. My bobcat starts up, idles, and goes through the tuning process without heating up, sagging, or dying out. If possible, try switching the cylinder head to a heli head that matches your engine.



    Wow, a very interesting suggestion, which makes perfect sense.

    The larger head would indeed help pusher planes.

    It seems obvious, but it's one of those "duh why didn't I think of that!" things...



    _____________________________

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    Build em'', fly em'', crash em'' and build more.

    (in reply to cyborg1)
           Post #: 3457

    RE: Nitro models pusher Bobcat? - 9/13/2008 10:07:46 PM   
    BillS


     

    Posts: 3077
    Joined: 9/6/2004
    From: Greensboro, NC, USA
    Status: offline     		Rod,

    I don’t know why the search engine does not work.

    Yes it is a lot to read but a treasure chest of ideas and suggestions.

    Bill

    (in reply to Rod Robbins)
           Post #: 3458

    RE: Nitro models pusher Bobcat? - 9/14/2008 2:40:23 AM   
    Boomerang1



    Posts: 902
    Joined: 6/24/2005
    From: Sydney, AUSTRALIA
    Status: offline
    quote:

    Looks great John!! You taking it to Temora?


    Hi Jeremy, yes, the whole gang is off to Temora, 2 jets for me this time round! - John.

    _____________________________

    Distributor for: Nothing! So my posts can be unbiased.

    (in reply to BillS)
           Post #: 3459

    RE: Nitro models pusher Bobcat? - 9/14/2008 10:10:50 AM   
    cyborg1


     

    Posts: 61
    Joined: 11/24/2005
    From: Bangkok, THAILAND
    Status: offline     		Well, went to the field today, and tried the 10x7 pusher. Overall, acceleration on ground was a bit better, but verticals or climbs weren't that good compared to the 11x6p. I couldn't tell much about speed in level flight, as i forgot my pump for the retracts and couldn't get the gear up. my flying buddies say that it flies fast, but it still seems slow to me, even at full throttle after a dive. anyway, i'm glad that it's up and flying again, next week i'll try the 11x6 again to see if it's actually better than the 10x7p. i still can't locate a canopy for my bobcast. vortex vacforms don't make 1 either. I sent an email to neo planes to see if they have spares, but didn't get a reply as of yet. any other suggestions for canopies?

    (in reply to Boomerang1)
           Post #: 3460

    RE: Nitro models pusher Bobcat? - 9/14/2008 5:55:02 PM   
    Xairflyer



    Posts: 313
    Joined: 12/17/2002
    From: Co. Donegal, IRELAND
    Status: offline     		I got my bobcat from www.planenutz.com in the uk, last time I looked on there site they mentiones that thay had bobcat canopies in stock as I thought I must get one as a spare.

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    www.letterkennymodelflyingclub.com

    (in reply to cyborg1)
           Post #: 3461

    RE: Nitro models pusher Bobcat? - 9/20/2008 11:00:14 AM   
    cyborg1


     

    Posts: 61
    Joined: 11/24/2005
    From: Bangkok, THAILAND
    Status: offline     		well, got 2 more flights logged with the bobcat. speed is picking up, which is great on low flybys, looking awesome! anyway, on my second flight, i left the spoilerons on by accident, and i accelerated down the runway. to my surprise, the bobcat lifted off gently when she got up to speed by herself. good way to take off, because when i manually rotate, the bobcat always takes off at a steep angle. another great use of spoilerons.

    (in reply to Xairflyer)
           Post #: 3462