Multiplex Fun Cub

[Andy Mc]

Posted by Tim Mackey on 01/09/2011 10:54:01:

At the very best, you will only see around 10.5V under load on a 3s lipo.

10.5 X 26 = 273

Still a long way short of 350 though, so sounds like you need a bigger prop.

Thanks for the info Tim, I just put my Watt meter on my Sebart Angel and the three cell pack was giving 10.3v, 43.5a and 449 watts. My Flightpower batteries are about 2½ yrs old now. I assumed that a freshly charged pack would be 12v plus and would drop a bit during the flight as the power was used.

 

I'm just making a test rig for this Multiplex Power-set motor to give that a test.

[Klippy]

The thing is, the Mpx motor is 840Kv with a 13x4 prop, to my mind, to approach anything like 30amps on 3s you're going to need 2000Kv+ or go to a 6s setup.

Stephen Grigg used the power setup from Mpx and was very happy with it but I don't think he measured the current.

[Andy Mc]

I picked up a universal motor mount from my local today so now I can bolt the motor to the bench.

On the bench I'm getting 11.3v, 22.2a, 251 watts @ 7700rpm on the APC 13x4e.

 

The battery is a 3 cell FlightPower Evo30 3200 mAh that I use in my Angel, but I'll get a couple of 2200 mAh packs for the Fun Cub to get started.

 

This should give me about 100 watts per lb, I'd like more but I'll see how she flies on this setup.

Edited By Andy Mc on 02/09/2011 19:39:48

[Tony Smith 7]

Mine flies nicely on around 160W with a Turnigy 3530 motor and 10x5 prop.

[Andy Mc]

Thanks Tony, it's good to know that she'll fly ok on 160w, some planes seem to need more watts per lb to fly, but the Fun Cub doesn't seem to be one of those judging by what I've read.

 

I'll just get it built and in the air now to see how she goes.

[Stephen Grigg]

Youll love it Andy and with mpx power itll be fine.Mine hasnt been flown lately because its developed a massive vibration.I can still fly using gentle power but its no where near as much fun.Mine is very well used now and I believe the problem is fatigue of the fron of the fuselage.I may try a new fuselage as mine has micro cracks everywhere.No hurry itll be ideal for winterIve tried a differnt motor and a new shaft.Ive an adequate motor that has done no work in a Southerner and may swopthat into it just to make sure its the fuz

[Seamus O'Leprosy]

I really think MPX need to improve that motor mounting system, the same one in my Acromaster is a nightmare.

[Stephen Grigg]

Theyve been using that method for some time I believe !!

[Gaz Elliott]

Check to ensure the mount is stilll completely attached to the fus. mine had a vibe on the twinstar. the mount was loose the first time then another time the plasctic sleeve was not completely stuck to the foam.

[Seamus O'Leprosy]

Yes I have had all those problems even though I followed the instructions on the addendum sheet. I just don't think the mount is up to the job, particulary when using powerful motors.

[Steve W-O]

The Twinstar and Funcub use two very different mountings.

 

My Twinstar has ply mountings to take the brushless motors. The standard plastic Twinstar mounting doesn't look very good, but it seems to do the job OK for those who don't change it.

 

The Funcub mounting is the same as the Mentor mounting, but the Funcub vibrates on full throttle (in the air, not static) and the Mentor does not, even when using the same mounting plate, motor and prop (easy to swap over)

 

Stephen, how many screws have you got holding the motor to the mounting plate? I only had two to start with, adding two more made no difference.

 

Next thing I want to try is a 3 bladed prop

[Stephen Grigg]

Yes I have just the 2 also,and and the twin star is very different but very small motors especially when brushless.

[ericrw]

On the demise of my Magister, I'm thinking of obtaining a replacement model; either a Funcub or a Mentor. What characteristics or qualities does the Funcub have over the Mentor ?

[Seamus O'Leprosy]

Flaps, a tow hook and bigger wheels

[Terry Walters]

Hi all fellow MPX Fun Cub owners!

 

Guess who got one for his birthday yesterday from SWMBO! I think she thinks it would be a good trainer for her!

 

Have to wait a bit before putting it together because I am away for a week or so.

 

I think I've got the makings of a decent power train up in the workshop but will need to rummage thro' the stocks to be sure.

 

What servos are you using for elevator and rudder?

 

I'll keep you posted with the 'build'!.

 

Terry

 

 

[ericrw]

Flaps maybe but not importent to my flying skill. Towing and big wheels not at all !! Anything else ??

[Seamus O'Leprosy]

Eric flaps are so much fun and on the Fun Cub you can drop them and fly at a walking pace with full control. and do short take offs and land in a ploughed field with the big wheels!

[Steve W-O]

Posted by eric loakes on 18/09/2011 15:43:22:

On the demise of my Magister, I'm thinking of obtaining a replacement model; either a Funcub or a Mentor. What characteristics or qualities does the Funcub have over the Mentor ?

 

 

 

I have both, and have flaps on both.

 

The Mentor is more like a conventional trainer, though it can do reasonable aerobatics in the right hands. It does need a longer take off run, and most people find it needs quite a long landing run, but it can in fact fly very slowly, and with the flaps rolls less than 15', but that is flying it on the edge of stall on approach.

 

The Funcub is as its name says, fits easily on one seat of the car (or in the boot), will take off from the top of the car, and on a moderately windy day, land vertically. It is comfortable to fly round a single football field, and can fly from small areas even if surrounded by trees.

 

Mine does not have the big wheels, but they would let you fly from longer grass than you could get a normal plane to move. I also don't have a very powerful motor. Gives good flight times from a 2200mAh battery.

 

Although people say it will land itself, it is still great fun to practice spot landings with, and I don't think easier than any other plane, though it is more forgiving than a normal plane just to get it down. It will drop a wing, but it looks like it has stopped before it does.

 

I've taken mine up in a strong wind (I had to be checked off by a new club, and couldn't wait any more!) when some one with a wot4 wouldn't fly after trying and finding it too strong to cope with. It wasn't exactly a smooth flight, but it wasn't scary.

 

I always take it with me, I know I will always get a flight in.

[ericrw]

Thanks Steve,which one of the two, Funcub or Mentor, copes best with windy conditions. say 10 to 12 mph. ??

[Steve W-O]

Posted by eric loakes on 18/09/2011 18:15:58:

Thanks Steve,which one of the two, Funcub or Mentor, copes best with windy conditions. say 10 to 12 mph. ??

 

 

 

I would rather fly the Funcub when it is windy, but the Mentor flies a straighter line.

 

Putting it very simply.

 

If you put two 4000mAh batteries in the Mentor, it is quite stable, and flies for at least 45 minutes!

 

Depends on where you are going to fly, can you head into the wind without going towards people or a no-fly zone?

 

With the Funcub, it is much easier to avoid things and places, you can take off and land across the strip (well the landing bit is up to your confidence with it)

[Klippy]

Terry, I used BRC 9gm units, they work great but you might have to pack out the servo bays a bit.

The Funcub doesn't have a tow hook option, the Mentor has, but don't got flaps, at least mine don't, did you cut your Mentor wing to add flaps after market Steve?

[Seamus O'Leprosy]

Sorry Tony you info on the Tow hook is erronious, as detailed in the instructions

"17. Aero-tow mechanism
The aero-tow mechanism 47 can be installed at any time.
The aero-tow unit should be glued in the recess in the righthand
wing panel. Set the servo to “neutral” and fit the output
arm on the servo, facing directly forward. Connect the towrelease
pushrod 48 to the servo output arm, then bend it to the
shape shown and cut it to length. Secure the servo in the recess
in the underside of the wing with a little hot-melt glue or cyano.

Fig. 25 "

 

Fun Cub MANUAL

[Klippy]

Seamus, you're exactly right, just shows, check facts before opening mouth! What's bothering me is that I have both a Mentor and a Funcub, the tow hook is fitted to the Mentor, but not to the Funcub, so I should have a spare laying around, but I don't!

[Seamus O'Leprosy]

Thats OK Tony. I know cause my mate has a fun cub and was all excited about his tow hook and now is too chicken to tow anything.( EFF when are you going to shed those feathers)

[Steve W-O]

Posted by Tony Prince on 18/09/2011 18:37:30:

Terry, I used BRC 9gm units, they work great but you might have to pack out the servo bays a bit.

The Funcub doesn't have a tow hook option, the Mentor has, but don't got flaps, at least mine don't, did you cut your Mentor wing to add flaps after market Steve?

 

 

Yes, I added the flaps, the Mentor has an allergy to the ground sometimes.

 

Now I can land it with a 6' roll, it comes in like a leaf falling, lot of stickwork to keep it heading the right way, and strangely have to use the ailerons not rudder, I think because I have a lot of differential, and the up going aileron is like a paddle in the water, drags it round to that side.

 

 

My Twinstar has flaps too, and an undercarriage