TPL33

Bought my Hobbico 60 Mark III trainer three months ago from a guy that would eventually provide me flight instruction. Since then, I've dinged up the two props to the point of replacement. The props that came with the plane/engine were APC 12X8. I went to the local RC store to buy new ones and the guy there said that prop was too much prop for that engine and recommended that I use an 11X7 prop. The OS Engine manual says to use a 12X7 or 12X8, which are the smallest recommended. Do most of you follow the engine manufactures recommendations or just use the prop that works best after trying them out? Should I use the 11X7 or get a 12X7 or 12X8?



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j.duncker

My Feedback: (2)

12 x 6 or a 13 x 4 will be better for a trainer fitted with that engine.

Get grey Graupner props if you can with Masters as a second choice. Avoid APCs as they are more inclined to break when dinged.

JohnBuckner

My Feedback: (1)

First I agree with both j.duncker and the gentleman from your LHS that is far to much pitch for that engine in a twelve incher. Which your engine manual also backs. The OS manuals are an ecellent place to start out with by the way.

I am currently flying a Senior Kadet with the 65LA that one of my students set up and the we found that the APC 13/4 or the 13/5 works very well for him and that airplane.

Now since you are training you can count on prop strikes and you will always needs spares, that is a given. Also for this reason normally I suggest (for training) the Master props simply because they will take more of a beating than most others and keep on ticking.

John

tschuy

My Feedback: (1)

13/4 is probably the best prop for the trainer. Doesn't load the engine up, keeps the plane flying at a manageable speed for a person to learn to fly and it works pretty well as an air brake when the engine is chopped to idle.

As John stated, plan on a few broken props and bring extra's. The APC props have very sharp trailing edges so Iwould recommend that if you get those props, take some sand paper and light smooth the trailing edge to help with the cut fingers. When that is done then of course go back and balance the prop as well. To learn how to do that, perform a search through the forums. But generally it requires a light sanding of the backside of the prop for the heavy blade.

Wood props are generally okay, but I tend to stap away from them as much as I can due to safety reasons when considering my fellow modellers. When one of those let go, its pieces flying all over the place. If I do fly with one then I start my engine away from everyone.

If any nicks or prop strikes to the ground, I don't take chances, just replace it. Hairline cracks are hard to detect and its not worth putting yourself or others at risk.

Maybe I'm overly cautious, but I don't want to be responsible for hurting someone else. I know how it feels when getting bit. I have the stitches and skin graph on a couple of my fingers to prove it.

markhamregular

Like all engine manufacturers, OS always recommends bigger props.
They want to stay in the safe side to minimize their claims.
I have a 10x7 on my 55AX and the recommended is 12x7.
Some people here may not agree with me, but I get the RPMs I want and my engine will run for years.


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52larry52

My Feedback: (1)

I bought one of those Hobbistar 60 trainers to learn on 11 or 12 years ago and after learning to fly it as a tri-gear I converted it to a tail dragger to learn tail wheel flying. It was one of those with the lousy sticky back covering and as it aged it got real ugly. I evently recovered the entire plane with red and white Monokote in a fax Cessna 180 style and I still have it and fly it from time to time. It's a great airplane that I use as a knock around flyer, a warm up plane and a windy day flyer. When your "trained" on it you are not done with this airplane...convert it, customize it and keep it in your hanger. Don't know if they are now covered with Monokote or if they still use the sticky back covering but either way you will like the airplane. Mine also is powered by an O.S. 65 LA and I use a 12-6 Master Airscrew nylon prop. Enjoy!

grosbeak

Whaddaya know - my Hobbistar 60 is a tail dragger now too. I put it in a tree early in 2012 and last fall I repaired the extensive wing damage and recovered the wing. When that was done, I did the tail dragger conversion.



I've decided to try a MAS 11x7 3-bladed prop, and the plane is on skis for a winter fun fly coming up on Saturday.

It's a great trainer and a fun plane all around!

Wing repair thread
Tail dragger conversion thread

jaka

Hi!
A 13x4 or 12x6 APC, RAM or Graupner "Sonic" will give better performance!

52larry52

My Feedback: (1)

Grosbeak, Yes, I remember seeing your repair thread. You did a nice job with the repair, the plane looks good. I didn't remember the tail wheel conversion though. With the long fuselage that these planes have they make a good platform to learn to fly with a wheel in the back don't they, less likely to want to ground loop. I generally only use a 3 bladed prop on a scale plane such as a war bird that would have had a multi blade prop on a full scale ( I like them for static looks) and I get the " it will go faster with a 2 blade" comment all the time. I reply "I didn't know we were racing"!! 3 blades will also help sometimes on planes with a prop to ground clearance problem. Use what you want!

jaka

Hi!
It's not speed you want in a trainer...it's slow speed climbing performance! That's why you use a large diameter, low pitch,two blade prop!

carrellh

Japan has very strict noise regulations so OS recommends very large props for their engines that may not give the performance you want. Lower rpm = less engine noise and less prop noise.
I agree with the several replies that most '60 size' two strokes seem to do very well with 11x7, 12x6, 13x4, and 13x5 props. I started with 11x7 on my first trainer and my instructor was not happy with it, especially when landing. He had a 12x6 with him and swapped it out, and felt it made a big difference. As I learned more I experimented with the APC 13x4W and liked it except for the expense. I broke 3 in one day, trying to learn to land, so I went back to the cheaper and more durable Master Air screw 12x6.