Flyboy Dave

My Feedback: (21)

I know a lot of you Guys bought the Magnum .91 four strokes during the sale
they had at Tower awhile back. What planes did you put them in, and what
props did you settle on ?

I have my own experience with the Magnum .91, and I love the engines.

FBD.

Campgems

14-4 15-4

I like the low pitch props. The only thing wrong with them is that they let me make my approachs to slow. I stalled and brused my 4*60 Friday by going to slow.

I think I had a 13-6 on my first 4*60 when I piled it in. The engine survived, but the plane sure didn't. I replaced the plane and am running a 14-4 on it. Pulls like a tractor. I'm just finishing a GP Super Aeromaster. It's going to be a heavy bugger. I'm going for the 15-4 on it.

Don

driesbabe

Hi Flyboy,
I have a few of the Magnums, and I run 14X6 or 15X4 APC's on mine works well for me.

regards
Dries

speedster 1919

My Feedback: (3)

Dave I got mine sitting on a 60 SPITFIRE. I am a 3 blade nut of the MAS brand. 12x8x3 will be first used but I have an 11x7x3 if the RPM's don't suit me. I bought 2 70's and they will probably like the 11x7x3's. I haven't fired it up yet..........My plane hauler engine blew up and needs my attention first................(VAN)

DarZeelon

Don,


The Sig 4*# planes are all normal planes that are actually designed to fly in the classic sense.

They are not intended to hover statically, or to perform 3-D maneuvers...

So, using a flat prop on this model is counter productive to the way it is intended to fly.


I don't know why you like flat-pitch props so much, but this specific model will fly much better; as it is intended to fly, with a 13x8, or a 12x10 prop.
A flat prop will slow this model down too much on the off-throttle part of the landing approach... and will not develop enough forward speed to fly it normally.

A 4* is not designed, like a 3-D model, to fly for extended periods in a 'mush'... It instead becomes 'mashed'...


Could your unfortunate crash be related to/caused by excessive prop-braking that resulted in a stall???

maineflyer

My Feedback: (44)

14x6 or 15x4W work best for me. Depending on the application

Gringo Flyer

My Feedback: (18)

I really like the 14X6MA. I tried the 14X6 APC and didnt notice much difference so I went back to the MA which is much more economical.

I have mine installed on a Funky 40 which is a 3D plane from CA models. It flies fantastic.

I have another one NIB that I plan on putting in a 4*60 next year some time.

alfredbmor

14 x 6 MA K series.

Cambo

My Feedback: (2)

I know i am going to get yelled at here but i have an MA 14-7 3 bladed prop on mine. I am running it in a hangar 9 hellcat. The sound is just great a fuel economy is even better. I havn't tached it yet but spool up is still VERY nice. I run the magnum on whatever my heli is using (usually cool power 15% heli). I like the extra oil for the in cowl applications.

The plane just ROARS down the runway.

carrellh

Mine are on:
PT-60
Big Stik 60
Four Star 60
All of mine have Master Airscrew K series or Scimitar 14x6 props.

My brother has them on:
Hog Bipe
Super Sportster 60
Astro Hog
Something else (maybe?)
All of his have Master Airscrew K series or Scimitar, or APC, 14x6 props.

I currently run 10% fuel;, my brother runs 15%.
For the type of planes we have, and the way we like to fly, the 14x6 works really well. It seems to be a good combination of speed and thrust. Some of our engines turn a few hundred rpm more than the others so we're thinking of trying a 14x7 on them to add a little more load.

Campgems

More likely by my lack of flying time, and slow reactions. [>:]

Don

blw

My Feedback: (3)

Campo,

Sounds like a good prop choice. Glad it is working out for you.

speedster 1919

My Feedback: (3)

Dave you said sale engines. I do have an older Mag 91-4 on a big stick 60 and slaped a 14x7 Graupner on. It worked OK but is just too much prop for great spool up and RPM was down. I can't imagine a 14x7x3 being a good choice for anykind of speed and performance. I.d like to see what CAMBO is getting for RPM.............Dave I'd try a MAS S2 as opposed to a K series for s#it$ and giggles..............

DarZeelon

Don,


I admire the courage you exhibited, to admit your own faults...

But, a surprising slow down by a model (due to the prop's pitch being too low to support speeds higher than the plane's stalling speed), can surprise even a seasoned pilot and even a full-size pilot in a full-size plane.

...And models don't have a stall warning chime/horn/buzzer, to hint to you to open the throttle, or lower the nose... It just happens 'out of the blue'... Don't beat yourself up over this.

Campgems

I was out this morning flying this morning and one of the guys commented on how "hot" my landings were. Thought I should slow down. I did a couple greasers and then managed to stall it again, trying to follow his advise. No damage this time.

I need to set up the "idle down" function on my transmitter. I just haven't taken time to figure it out yet. I'm not ready to go with the higher pitch props, the low pitch has more than once alowed me to save the plane when I got in trouble. Nothing line being able to jam the throttle from dead idle and have the plane pulling out within a few hundred micro seconds. I guess I'm still a drag racer at heart.

Don

submikester

My Feedback: (6)

There's nothing wrong with a low pitch prop on a 4*# they fly great fast or slow.

I've got 2 of the magnum 91 4 strokes and the best prop for me has been an APC 14x6 for sport. Sometimes I will use a MAS 14x6 but they scare me as they flex so much. Also with good results I have used Zinger 15x4's & 14x6s. 14x7/8 seems to be just a little much as does a 13x8.

speedster 1919

My Feedback: (3)

SUB Think about this--The MAS K scares you-- but when the ground or pavement strikes the MAS K it is not scared. You won't find a tuffer prop...............

Flyboy Dave

My Feedback: (21)

If you sport flying Guys want a big surprise in performance, put a MAS 12-8 K-series wide
blade prop on that Maggie .91FS and see what happens....You're in for a treat. Be sure to
balance the prop, spinner and backplate as usual, at least get them close.

There was another thread where a couple Guys tried them on my recommendation, and
were pleasantly surprised by the performance....much more that was expected.

True, I have seen a MAS prop that did wobble slightly, but not a problem. The engine only
senses vibration from an out of balance prop, not one where on blade is slightly out of
alignment with the other. This of course does not effect the performance of the prop either.

Trust me, for sport flying....the 12-8 MAS is great. [sm=thumbup.gif]

FBD.

rtmusic

Hmmm, I have an old original Bridi Dirty Birdy with a Magnum .91 FS using a 11x10 presently. Sometimes I use a 11x8 to get a little less speed and more torque I guess. But with the 11x10 it has lots!!! of torque and the speed is good, obviously, with the 10 pitch. The 11 size is due to ground clearance mostly, but it revs between 9 and 10,000 very steady too. Recently having trouble with the idle remaining steady and/or dead sticking. Might be time to go through the engine due to the 100's of flights on it. Or time to retire it?

wcmorrison

My Feedback: (2)

I too use the MA K series prop on my Maggy, it is a 14 X 6. The plane is a Great Plaines 60 sized Stik. Unfortunately it took a mid air and now I am down to just an engine. Now flying a Saito 65 on a Ultra Stik knock off, using a MA 13 X 8 K series. Does a good job of pulling a round a fairly big plane.

takEon

13.5 x 8 Graupner . I use it on aerobatic planes in the 65" range. I am very happy with it in this role.

jaka

Hi!
At sea-level a 13x8,14x6 or 15x4 is the best prop size depending on model. For best performance use a Graupner G-Sonic, RAM or APC prop!
Ma is no where as good as those even though the scimitar series is close.