Prop selection for Max Thrust Riot

[Stuart Marsden]

The Max Thrust Riot has become very popular for good reason, being described with movements reduced as a good trainer to a fully aerobatic aircraft with movements increased. I have returned to our Sport. I now have one of these fine machines and would be interested in tried and tested prop combinations on 2200mm 3 cell packs with original ESC. Your thoughts please. Potty Flyer

[Colin Carpenter]

Stuart - mine' s still flying on the original after 250 flights. I have tried an APC 12/6 CLONE which was a little noisier but still got 7 minutes of aerobatics . Colin

[MattyB]

Forget "tried and tested" - one slip of the keyboard is all it takes for someone the other side of the world to accidentally trash your motor or ESC. The alternative? Reach for the wattmeter. Here's my method:

1. Run the stock setup at maximum power on the ground and note the max current pulled. Alternatively if you have a current sensor and a TX with telemetry capability you can do this in the air.
2. Is the max current within 10-15% of either the max motor or (more likely) the rated ESC current? If it is you don't have enough room to increase the max wattage without replacing the limiting component with one that can handle more current. Stick with the current prop or if you want more speed go down 1" in diameter and up 1-2" in pitch and restest.
3. If you have more than 15% on both the motor and ESC, you can increase the load (and therefore current) on your powertrain. For more thrust go up 1" on the diameter but keep pitch the same; for more speed up the pitch by 1-2" and keep the diameter the same. Retest with the wattmeter to make sure none of your components are overstressed.
4. Fly the new combo and see if it is to your tastes. Remember increasing power and current decreases flight time, so set your timer at least 2 mins shorter for the first flight and check capacity used afterwards. If you don't like the new setup return to step 1 and repeat.

Good luck, and happy experimenting!

Edited By MattyB on 07/05/2016 19:39:11

[Stuart Marsden]

Many thanks, I have a watts meter and willexperiment this way. I just wondered if fellow flyers had come up with better solutions. The standard props appear crude, I struggled tobalance one of the two supplied. More advice welomed Potty Flyer

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[MattyB]

Yeah, stock props on parkflyers at this price point tend to be utter junk - my Dad's foam-E Acrowot came with a prop seemingly made of cheese. He stuck on a genuine APC-E and got substantially more thrust for less amps!

Edited By MattyB on 07/05/2016 21:22:45

[Geoff S]

After a little contretemps with reversed ailerons (don't ask because I don't know!) on my original Riot with over 200 flights to its credit I bought a new airframe and so it's like my grandad's hammer (3 new handles and 4 new heads) and keeps soldiering on. There are very few flying sessions when it's not in the car.

It still has the original motor and esc both rudder and elevator servos have been replaced with metal geared ones from Airtek because of stripped gears. The original prop lasted a very long time but has been replaced with a cheap 12x6 from HobbyKIng which seems to perform more than adequately for my very modest flying skills. I can't remember exactly what the current draw is but it was checked and found to be within the limits of the supplied esc (30 amps IIRC).

I had few flights yesterday. Each lasted about 8 minutes actually in the air (9 minutes after the taxi out and back) and the batteries (2200 3S) still had about 25% capacity (I was impressed by my new, and expensive, Graphene pack which still had a 40% reserve!). I do practice a lot of throttle control but my flights are quite aerobatic and usually include at least 2 touch and goes because I'm trying to improve my landing skills.

So I've never really bothered about further experiments beyond removing the steel weight and increasing control movements. It is, without doubt, the best value for money model I've had in terms of flying time v workshop time as well as cost/flight. I love it.

Geoff

[Stuart Marsden]

Thanks for that, different battery suppliers appear to give different results, I am using Overlander via Inwood Models and get consistent 7 minute flights on the standard prop and setup, leaving about 80 percent in the cells above 3.75 per cell. PottyFlyer

[Former Member]

[This posting has been removed]

[Old Geezer]

Sort of the same subject - I swapped the manufacturer's 12 x 4e for a same spec' APC on my Parkzone Sukhoi - seemed to go much better, and less noisy too.

A question for the experts, are noisy prop's less efficient? Thinking about it, noise = turbulence (I guess) which by it's very nature means some of the energy that should be expended pulling my Sukhoi through the air is wasted overcoming drag on the prop' cutting it's spiral through the air, which is evidenced by the greater noise produced by the rotating prop'. ( I know, the prop' is a rotating wing, not a screw, but you get the idea. )

[Geoff S]

Posted by Percy Verance on 08/05/2016 08:15:54:

You just have to get those landings right Geoff. After all, there's one every flight......

Edited By Percy Verance on 08/05/2016 08:16:39

In my case there's often several but we all land eventually. It's just a case of if the model is ready to take off again without a lot of workshop time ... or even at all

Geoff

[Dave Hopkin]

Posted by Gurth Scriven 2 on 08/05/2016 08:29:43:

Sort of the same subject - I swapped the manufacturer's 12 x 4e for a same spec' APC on my Parkzone Sukhoi - seemed to go much better, and less noisy too.

A question for the experts, are noisy prop's less efficient? Thinking about it, noise = turbulence (I guess) which by it's very nature means some of the energy that should be expended pulling my Sukhoi through the air is wasted overcoming drag on the prop' cutting it's spiral through the air, which is evidenced by the greater noise produced by the rotating prop'. ( I know, the prop' is a rotating wing, not a screw, but you get the idea. )

Energy in a system is never lost, it is converted into different forms - Thrust, Noise and Heat, that applies to any system.... so the noisier a prop is the more wasteful its being with energy

[J D 8]

You are not wrong Gurth,the correct name for a prop is an Airscrew .but prop has become the standard term like Shock has for dampers on a car.

[Andy Butler]

I swapped out the stock prop for an APC-E 12 x 6 and it has more power and is a fair bit quieter too. I also put slightly bigger wheels on it rather than the foam ones it came with. I have a 9 minute timer linked to the throttle stick programmed in to the Tx and the batteries come down with about 25% left.

[Stuart Marsden]

I have bought one of these props. I am also advised the 13x6 will also improve performance without drawi down the battery significant. Has anyone tried this?

[Geoff S]

You say you have a wattmeter, so the only way to find out is to try it. Just make sure you keep the current well inside the rating for the esc (30 amps IIRC). I don't think the motor specification is published so you're going to have to assume it matches the esc. Whatever the current, a quick test (< 30secs) is unlikely to cause any damage. I would say you're OK if the current stays under 25 amps. What current draw do you get with the existing set up?

Even with the higher maximum current that fitting a bigger prop will entail, if you exercise reasonable throttle management then overall endurance may not change too much. If you fly flat out the whole time then obviously you'll exhaust the battery sooner than with a 12x6 prop.

Just make haste slowly and check the battery after each flight and extend/reduce flight times accordingly.

Geoff

[Stuart Marsden]

Many thanks for this, I get watts metre out and some extensive tests. Best regards

[Jonathan W]

The original prop on mine was too far out of balance to be much use, so I replaced it with a Master Airscrew Electric 12 x 7. This has been fine for the past couple of years or so.

Edited By Jonathan Whitelegg on 11/05/2016 23:51:17

[Stuart Marsden]

Interesting, as my original prop was just the same. Have you done any tests with a watts meter or is it a case it's works, that's good enough? I would be interested in how long your flights are. Best regards Stuart

[Jonathan W]

I did test with a watt meter at the time and the result was "safe", though I can't remember the details now. The original motor and ESC remain intact after more than 2 years use. I set my timer to 8 minutes. When I changed to the Master 12x7, it needed less throttle than with the original prop for the same performance. The Master is a nicely made prop, with a very thin and accurately formed under-cambered section.