sbritton

I'm considering the Bobcat 25, but the website just does not provide enough info to make an informed setup. Specifically what I'm looking for:

1. A PDF version of the install manual.
2. What Brushless motor would be a good choice for a really really fast model (90-120mph). (I have 3,4,5,& 6 Cell Li-pos available)
3. What diameter motor is needed to use the supplied motor mount?
4. If you don't use the supplied motor mount, how else could you mount it?
5. Should you use an inrunner or outrunner?
6. How many & what size/spec servos are required?
7. Is it possible to use retracts? If so, any ideas on make/model?

Thanks!!

opjose

Ok here we go..

1 - The manuals are merely pictures anyway. Other than the C.G. and a basic "pointer" in the right direction, you should be able to put the plane together yourself w/o the manual... it's actually a pretty easy build if you have prior ARF experience. If not you'll need help.

2 - Re: Motor It's up to you. I'm putting in a 500-600 watt Tower Pro ( BP hobbies sells it as a BP 2915-5D See: [link=http://www.bphobbies.com/view.asp?id=V450327&pid=W392031]CLICK ME![/link] ) motor that I have with a 60A Tower Pro ESC from Nitroplanes.

This plane will SCREAM with a high pitch smaller prop and an 11v LiPo pack...

3 - The motor mount has oval cutouts to accept different sized motors. Anything in the 300-500 watt range should fit fine. More may require only minor modifications.

4. - That would be up to you. You would basically be recreating the supplied mounting "box" which already pretty good. Check the threads on the bigger .52 bobcat, and see how others have mounted everything from electrics to turbines on that plane. The mounting platform is IDENTICAL on the .25 bobcat, basically a slab of VERY hard wood which has a thick fiberglass fuselage over it... I remove a lot of the fiberglass on my .52 to mount my oversized engine lower... the sturdyness of the wood used there was impressive.

5. - Re: In/out runner

Sounds like you are new to this. Inrunners are typically used with gearing systems. Outrunner is the way to go with the Bobcat .25.

6. - Six Micro servos, preferably higher torque onces... Those 8.00-9.00 ones Nitroplanes sells work work great for this as their torque is good.
Just make sure that the ESC can accept the load or it will cut out... for instance many of the E-Flite ESC's will cut out with more than 2-3 non-E-Flite servos... their one board BEC is trash....

7. - Micro ( plastic ) retracts may be possible. Hobby-Lobby has a few that may be suitable.

Frankly I wouldn't bother though. The plane will be very fast as is, and installing the Micro retracts is going to involve a good bit of modifications... you sound quite "new" to this so I'd advise against it. The nose steering alone will be a pain.

sbritton

Great...thanks for the wonderful response & details.

I'm actually pretty experienced with electric planes but this one seemed to really be lacking good info on their website like other planes usually do. So far I have owned a FuntanaX50, Ultimate Bipe, Stryker F27C, Typhoon, Fliton Extra 330S, Fliton 540Mini and my fav is the Kyosho Kelly F1 racer (yep...all of them electric). Okay...my wife gets on my case about the fleet already.

The motor issue really threw me for a loop as the pictures of that red mount appear to surround the motor, which means an outrunner would not work, but their site said to use an outrunner. Like I said, I haven't seen that kind of mount before so assumed it was a typo and an inrunner is what is needed. But sounds like you have this one dialed in pretty well.

I think you are likely right about the retracts as well. Seems to be more hassle than it is worth for something this small.

I'd be interested to hear how fast folks have gotten this model to go and the setup they have (prop & motor). Obviously the Stryker I have with it's upgraded himax motor and 4S battery gets well over 90mph. The Kyosho Kelly F1 easily hits 100mph...but Im still trying to dial that one in by playing with different props..

opjose

The motor mount can accept a standard Outrunner "X" mount and screws w/o problems. The motor is then mounted outside the box.

The box is big enough to accept a rear mounted outrunner as well.

This plane is heavier for it's size than the Stryker and has a very sleek profile, so speedwise it should keep up with the Stryker w/no problems.

However you can easily fit a bigger battery and ESC than what the Stryker can accept, so it should haul with the motor I have for it.

I use the same motor on my SuperSportster EP and it is very fast.

The one thing I don't quite see vis-a-vis the printed specs, is the weight of the plane.

The docs say it will come in at 3.9 lbs.

I'm more inclined to say that with the electric motor it will come in closer to 2.6 lbs. Much like my SSporster... which has a slightly bigger wing span.

opjose

Re: the number of servos required.


It depends...

One for each rudder, two for the elevator ( one on either side ), one for each aileron, one for the throttle ( if glow ), and one for the nose wheel steering...

So it's seven or eight...

opjose

On another thread there is a question about using the 500T motor.

The 500T motor is rated at about 250 watts output.

The specs state that the AUW of the plane is about 3.8lbs ( which I seriously doubt... ).

That would produce a fairly LOW power to weight ratio.

At 2.6 - 2.8 lbs, which I believe most setups will come in at, you get a bit more respectable ratio of close to 98watt/lb.

Since the prop will unload in flight, especially on electrics, this may give you decent flight characteristics, but the plane may not be able to accelerate when traveling straight up.

I prefer a MUCH higher ratio to attain very fast speeds, so I am putting in a 500-600 watt motor into my plane and a 60A ESC to go with it.

wingbeat

My Feedback: (2)

Opjose-

Thanks for all your posts on the Bobcat/ Falcon 25. Some great info!

I haven't decided what to power mine with yet. Looking at 2 -stroke, but have researched quite a bit on inrunners.
I wouldn't rule them out. Afterall, non-geared inrunners are used by some of the fastest e-powered rc planes, F5D , "hotliners", pylon racers! (megas, neus, plattenberg, etc.)

There's a few of us over on rcgroups trying to sort it out a decent 100 mph+ system. Looks like Tumbler has got a Medusa 36- something-something on the way to run on 6S with great numbers. (He also fitted retracts!)

I'm looking at using a Mega I bought- 22-30-2. Run on 5S the charts tell me I'll get 160 mph prop speed, 100 ounces of thrust!
Amps will be high at WOT- around 52. That's a 900 watt input/ 826 out. lol.
But of course, the online calcs can be waaaaaaaay off, so this is probably very optimistic.
I'm not sure a small 5.9 x 5.9 speed prop will really generate that amount of thrust.

Haven't looked at any numbers for an outrunner on 3S - have you flown your tower motor yet?

cheers,
'beat