Author Topic: small prop for trainer (Read 906 times)

Peter in Fairfax, VA · « **on:** November 01, 2021, 10:11:19 AM »

Sometimes I wonder if getting a trainer to fly slow is a good idea. Beginners actually like the line tension that comes with lap times.

My question: Are the 10x4 APC props I just ordered for an LA 46 going to be good trainer props? My thinking was the light load would allow less critical needle settings than the Rev-Up 12x5 cut to 11-1/2" I normally use.

Thoughts? If these props don't work out, not a problem, as we'll break 'em soon enough.

thanks,

Peter

Dan McEntee · « **Reply #1 on:** November 01, 2021, 05:41:41 PM »

Give us the specs of what you are flying. What airplane, weight, line length and such. Line tension is a function of several variables and prop is one of them. And are we talking about doing the pattern, at least the beginner pattern? The LA.46 is a lot of engine. I have had them on models where it was difficult to get them detuned enough to be consistent, and was better off dropping down to a .40 or a .35. You can only go so far before it's too low below the curve. Fill us in on the rest of the details.
Type at you later,
Dan McEntee

Peter in Fairfax, VA · « **Reply #2 on:** November 02, 2021, 05:40:14 AM »

At present, the plane/engine combo is an LA 46 on a standard Sig Twister. The student pilot has mastered "basic flight" and is ready to try some loops, lazy eights, etc. Probably using .015 x 58' lines. The plane will do the pattern, though it does sorta stall at points.

Dan McEntee · « **Reply #3 on:** November 02, 2021, 07:20:12 AM »

Quote from: Peter in Fairfax, VA on November 02, 2021, 05:40:14 AM

At present, the plane/engine combo is an LA 46 on a standard Sig Twister. The student pilot has mastered "basic flight" and is ready to try some loops, lazy eights, etc. Probably using .015 x 58' lines. The plane will do the pattern, though it does sorta stall at points.

You should be able to get that combination to run between 5.3 and 5.5 second a lap pretty nicely. Put the smallest venturi you have in it, hopefully down in the .250 range, or you may have to try the old stick in the venturi trick. Check out the wing for any warps, the alignment of the other surfaces, and if the hinges are not sealed, apply some tape to the hinges, being careful not to make the controls sticky. Get a variety of 11-4 props and tach to the 9,000 RPM range and see what the lap times are like and how the model feels. Speed up and slow down with the needle as needed. Check lap times each flight and time the length of the engine run each flight. As you gain some insight into things, try the other brands of 11-4 props to see if they run better, worse or the same. You will see a difference. The 10-4 props you have will probably be too small, but I have used those on .25 and .35 sized engines with good results.

If you have an LA.40, you might want to try the same combination but will need to lean it out some and forget the stick. It will be more in a range where the engine likes to run than it will be with the .46.
Keep us posted,
Dan McEntee

BillP · « **Reply #4 on:** November 02, 2021, 07:48:25 AM »

Ditto on 11/4...

Ken Culbertson · « **Reply #5 on:** November 02, 2021, 09:21:04 AM »

Quote from: Peter in Fairfax, VA on November 02, 2021, 05:40:14 AM

The plane will do the pattern, though it does sorta stall at points.

I trimmed out my Twister to do the pattern quite well using a .46 size electric. It does not like to fly slow. At 5.5 on 58' lines (I flew on 60' at 5.1) it may be too slow to keep from stalling in corners. Sealing the flaps was a huge performance jump on mine. I also found that it cornered better using a 3/4 flap to elevator ratio but it did better rounds using a 4/3. If you are at 1/1 keep it there. I also found that my LA46 (on another larger profile) did not perform well on low pitch props and high RPM's. It may have just been mine but it really purred running a fast 4 on an 11-5.5 or 6. Also got some nice runs on a 10-6 three blade.

Good choice for learning

Ken

Peter in Fairfax, VA · « **Reply #6 on:** November 07, 2021, 03:54:11 PM »

The 10x4 APC on the LA 46 worked out just fine. I like a light load like that, as the needle is less critical. The student pilot did his first loops with no problems, getting in five in his first flight attempting them. Lap times varied a bit, but were about 5.3.

Dan: What is the "stick in the venturi" trick? I get the concept, but not the implementation

Ken: I've been hearing about "sealing the control surfaces" for forty some years, but have lost track as to how to do this. For example, on an existing model with Monokote, silkspan, etc.

Dan McEntee · « **Reply #7 on:** November 07, 2021, 04:17:09 PM »

Quote from: Peter in Fairfax, VA on November 07, 2021, 03:54:11 PM

The 10x4 APC on the LA 46 worked out just fine. I like a light load like that, as the needle is less critical. The student pilot did his first loops with no problems, getting in five in his first flight attempting them. Lap times varied a bit, but were about 5.3.

Dan: What is the "stick in the venturi" trick? I get the concept, but not the implementation

Ken: I've been hearing about "sealing the control surfaces" for forty some years, but have lost track as to how to do this. For example, on an existing model with Monokote, silkspan, etc.

Hi Peter;
It must be a light model, but I'm for whatever works. Just keep things as they are for right now while he builds up handle time. The Stick in a the Venturi Trick is a piece of wood about 1/8" square or so, with a taper on one end and wedged into the front of the venturi. This reduces the size of the venturi and necessitates the needle being turned in a bit more stretches your fuel mileage, and reduces power just a bit. I've had OTS models with less than adequate tank capacities in them and flew with a stick in the venturi of a Fox .35 for years! The 10-4 is obviously working, but a secondary benefit may be what he sees when sees and feels what happens with a 11-4 as far as line tension. But for now, one step at a time. Keep us posted.
Type at you later,
Dan McEntee

Ken Culbertson · « **Reply #8 on:** November 07, 2021, 05:04:55 PM »

Quote from: Peter in Fairfax, VA on November 07, 2021, 03:54:11 PM

Ken: I've been hearing about "sealing the control surfaces" for forty some years, but have lost track as to how to do this. For example, on an existing model with Monokote, silkspan, etc.

It is using thin tape to close the gap between the flaps/elevator and the wing/stab. It stops air flowing through the gaps. A search should turn up some techniques. It is really quite simple and can be used on any surface. Done properly it is practically invisible on the bottom.

Ken

Brett Buck · « **Reply #9 on:** November 07, 2021, 07:36:12 PM »

Quote from: Peter in Fairfax, VA on November 07, 2021, 03:54:11 PM

The 10x4 APC on the LA 46 worked out just fine. I like a light load like that, as the needle is less critical. The student pilot did his first loops with no problems, getting in five in his first flight attempting them. Lap times varied a bit, but were about 5.3.

Dan: What is the "stick in the venturi" trick? I get the concept, but not the implementation

Ken: I've been hearing about "sealing the control surfaces" for forty some years, but have lost track as to how to do this. For example, on an existing model with Monokote, silkspan, etc.

https://stunthanger.com/smf/stunt-design/hinge-options/msg99465/#msg99465

Author Topic: small prop for trainer (Read 906 times)

Peter in Fairfax, VA

small prop for trainer

Dan McEntee

Re: small prop for trainer

Peter in Fairfax, VA

Re: small prop for trainer

Dan McEntee

Re: small prop for trainer

BillP

Re: small prop for trainer

Ken Culbertson

Re: small prop for trainer

Peter in Fairfax, VA

Re: small prop for trainer

Dan McEntee

Re: small prop for trainer

Ken Culbertson

Re: small prop for trainer

Brett Buck

Re: small prop for trainer