Jon H

I wouldnt touch them with a 10 foot pole. Obviously no brand is 100% perfect when it comes to reliability, but you are stacking the deck in your favour sticking with known brands like Futaba, Savox and hitec. As there appears to be no significant saving when it comes to cost either i would simply walk away.

https://www.kingslynnmodelshop.co.uk/savox-sg-0351-standard-size-digital-4-1kg0-17s/ Same price, better servo. Normally i would agree the 311 is fine, but they arent £5.99 any more and do not offer great value.

digital servos hold slightly better, are slightly more accurate etc so can give a slightly more crisp feel. Its pretty subjective mind you and i only use them as they happen to be good on the price/performance ratio while still being a known brand rather than a no name from ali express. Using 4, 5, 6.5, 9 and 11kg analogue and digital servos over the years i cant tell the difference in the air. The models i fly, my flying style etc. Generally i just dont notice the difference. Admittedly my acrowot xl with savox 352 digitals is noticeably crisp and responsive, but as i have never flown it with other servos i cant tell if its better/worse. On the power useage, its not a concern in a model like this. If you had 10 high power (10kg plus) digi's and were slapping the controls about like an animal it would matter, but i use 6v nimh batteries and have no issues. For the model you have digital is no advantage, but if you are buying 4 servos for X cost and you can get digital then i would do so as you can use them later. The savox also share output splines with Futaba and have the uneven number so you can mechanically centre the arms with ease. Hitec do not have this and i have stopped using their servos because of it. I had 4 hitec servos going in a model and they all had wonkey arms which required a bunch of sub trimming and faffing about. This was impossible for the ailerons as i wass using a y lead, so i swapped in some futaba's instead.

Check out the savox 351. Similar price and marginally better spec as its digital. I use them all the time in my WWII stuff on ailerons/rudder up to 90 inch

The problem is, you want the negative expo as it is an aid to things like a landing flare as you end up with softer sticks at greater deflection allowing greater accuracy. However, the servo rotation argument is pretty meaningless if, like many, you fit a 2 inch servo arm and reduce the servo travel to 20% to get the required deflection. Very few go back and move their control linkage closer to the servo or fit a smaller arm. All of this can be achieved without the 5p approach. There is also a misconception about switch flicking as it is mostly confined to takeoff/landing for my warbirds, but hardly ever at all for sport/aerobatic models. I have them set to do all i want them to on a single rate for the most part. To be honest though switch changes are such a non event i am not sure why its such a concern.

Obviously i cannot speak for you but there should be very little workload associated with having a flying rate and a landing rate. Assuming you use the landing rate for takeoff as well its only two switch flips per flight. Admittedly i am very used to flipping switches as most of my models need me to flip gear up, elevator rates low and timer start all within the first 4 or 5 seconds of the flight. Landing is similar with switch flips needed for gear down, flaps half, elevator rate high, aileron rates as required, flaps full. I make my life easier though by flying a proper landing circuit with points of reference on the downwind for each action. This means each is spaced a few seconds apart giving ample time to keep up with proceedings. in either case, i have a practiced procedure stuck in my head and i never deviate from it. Its 2nd nature and i do not even think about it, i just flip 'em. While i can understand the desire to keep things simple you can degrade the performance of the model with this approach as the setup is a compromise. Having two sets of rates, or a flight mode for different phases of flight gives you enhanced controllability and hopefully, more enjoyment of the model. My Warbirds would be so difficult to fly/land without having the setup i do and i wonder if this is why so many folk struggle with warbirds. Its not the model, its the setup.

Its been done about a million times, usually causes a disturbance in the force once we all get going 😉

You do sometimes get engines that just dont work for some reason. I had a saito 180 that never ran as fast as the other one i had and behaved more like a 150. When you run as many engines as i do the differences between them become very stark, even when they have identical theoretical performance. I have test run batches of engines here where some run as expected, but others are just more 'alive' than their mates, while others seem flat and dead by comparison. They all do the same rpm at the top end, idle well etc and so all pass their test run. Its just they have different characters for some reason. I am probably the only person that would actually be able to tell the difference, but to me its very apparent. In the case of the NGH, i wonder if the cam was incorrectly installed due to the timing mark itself being in the wrong place. Had this on an enya 53 that a friend asked me to run in. It just didnt perform, so i checked the timing and saw it was wrong. The timing marks were correctly put together, but the angle of the cam was wrong. I spotted it right away as the enya and laser cam timing/cam profile are extremely similar and it just looked wrong. I compared it to my own 53 and this confirmed my suspicion.

Poor Flyboy didnt know that 😉 I use rates alot on the warbird stuff. I normally need more elevator authority for takeoff/landing and have a higher aileron rate to help me out when landing in choppy conditions. The high rate is also there to help me if an aileron servo decides to die as the increased authority will be helpful if i am down to one, and vital if the servo fails when it is not in the neutral position. If it failed at full deflection on low rate, i need a higher travel from the remaining one to stand a chance of over powering it. Sure its a very unlikely scenario, but its not impossible and its just another line of defence against a loss of control.

18x8 should be very acceptable for a 30cc class 4 stroke. I recommend 18x8 for our 180/200 as more or less the standard prop and i would expect 7500-8000rpm ish depending on the engine and the brand of prop. Aerostar props run fairly fast, so i would be expecting near the top of that rpm range for our engine. Saito always seem to want their engines to rev like mad while spinning a tooth pick. Not sure why. The little saito 45 i have in my Nieuport is turning a 15 inch prop at 6400rpm flat out and i have no bother with it at all...as long as i do not use full throttle for more than about 10 seconds as it then it gets a bit annoyed with me as the temperature rises. As i never need to fly it flat out its simply not a problem. The saito 170r3 i recently worked on recommends a maximum prop size of 16x8 using 15% nitro fuel, but i ran it very happily on a 17x8 using 5%. In fact i wouldnt dream of running it on anything smaller or using more nitro. It ran fine, and even better once i tweaked it. In any case the manual says a 15x8 will run 9400rpm, which works out to 2.4hp calculated. My 17x8 effort ran at 7800rpm or 2.28hp calculated so the engine is still quite comfy in its torque band. Thrust was up by about 2lbs, max pitch speed down a bit, but the thrust increase likely negates this. Propeller tip speed was down by nearly 12m/s so tip noise would be reduced as well. In this instance, there is no disadvantage to the big prop. Incidentally, you can often run larger props with low nitro than you can high as lower nitro fuel slightly reduces compression ratio due to the leaner (number of turns not actual mixture) running of the engine and less incompressible liquid in the cylinder. The petrol radial here will be more tolerant of a big prop as the ignition will not advance with the increase in head temperature like it would in a glow engine. Personally, i would expect to see 7500-8000rpm on an 18x8 and went looking for rpm numbers on these engines as your 6500rpm target seemed low. Reading reports online of 18x6's on these engines running in the 8400-8800 range, then subtracting the 500rpm/inch broad estimate of increased load from the 18x8 vs 18x6, we end up at 7400-7800rpm which is in line with my own prediction. If you are only seeing 5000rpm on an 18x8 there is either a substantial mixture problem, or you are missing a cylinder. If its only running on 2 that would explain the big loss of power. In your earlier video it was running on 3, but you may have an intermittent fault on a spark plug or something causing a cylinder drop out.

How many RPM did you get? and on which prop? I know i have made mention of this a number of times during this thread but you cannot tune/setup/operate engines by fixed numbers. This many turns on a needle, so many rpm, this cylinder head temperature etc. Engines a more nuanced and at our end of the scale they vary massively day to day. As an example, if i say to a customer that one of the Laser engines should do X RPM of Y propeller, i know that anything +- 200rpm on that figure is perfectly normal. Unfortunately, trying to explain to customer A that his engine is fine at 8400rpm despite customer B reporting on a forum that his example of the same engine does 8800rpm on the same prop is very difficult and customer A feels he has a dud engine. But is it the same prop? Different brands will run at different speeds despite the same DxP. In fact i have two seemingly identical APC 16x8's here and they run 500rpm apart when tested back to back on the same engine. It seems APC changed the design somewhere along the line as customers have reported similar issues to me and even sent me their props to test. Also where does customer B fly? Is he in a hotter climate, colder, higher altitude etc. There's a customer in Austria who is half way up a mountain and his engines rev like crazy as the air in thinner. Power is down for the same reason, despite the higher rpm. Day to day variation can easily be 200rpm even here in the UK so the engine might have been fine. Clearly if you were 1000rpm down something is not right. Without observing your procedures for running the engine and having all the data its hard to say what the problem is. However i fear that inadequate adherence to tuning procedures, unfamiliarity with the engine, unnecessary fiddling and dismantling of the carb (in my view as blowing air through a pumped carb can ruin it), and an over reliance on numbers is likely to be the root cause of your problems. If Morris finds a dead otter in the carb or other problem then fine, i will gladly eat my words but i do not think he will find much. If there is a dead otter in the carb why is it there? Where did it come from? Always wash out your fuel system and check for otters (or more likely, grass and fluff).

Nice catch. This is why my maiden flights are timed at 5 minutes with nothing beyond takeoff, trim, stall test, land in the schedule. Once on the ground wing off and inspect everything. 2nd flight is a little more exciting but another inspection post flight. Last model build i found a broken bracket for one end of the elevator servo after flight 2 while inspecting it before flight 3. Needless to say i packed it up and went home with 2 flights only.

Agreed. This is the key point though, need. If they need it then by all means go ahead. I have on mine, and its fair enough. My beef is using 30% straight out of the gate while flying around with twice the rates the model needs. This is not helped by donkey recommendations from many kit manufacturers when it comes to both c/g (too nose heavy) and rates. My order of operation when setting up a model would be c/g, rates, test fly, rates adjust, fly, rates adjust, fly, c/g adjust, fly, rates, c/g, rates etc...with those two set, then expo is the clincher if you need it.

I rarely use it on anything. I do have 10% on 1 channel each on 2 models as it was just the cherry on top when it came to the setup, but its 2 out of 36 primary flight channels in my fleet. I would always recommend you start with none, get the rates right (most models are flown with very excessive rates which makes them twitchy) and then add some expo at the end should you need it. When it comes to setting the rates the ailerons are easy as you just keep lowering them until you get the maximum roll rate you want at full stick deflection. Similar story with the elevator, just keep decreasing it until you feel you are running out with the stick hard back, then add a little back in until its comfortable. I have flown loads of models where you never move the stick in a circle bigger than a 5p piece as the rates are so high. Its not a nice way to fly so drop them down and use the full stick travel instead of expo.

I flew on Saturday for the first time since September. The field was like a marsh, but my nieuport 17 was able to handle it. Its very grubby now, but did look great against the angry sky.

If its been MMM modified it will may have the intake 'upgrade'. I say it like that as i took a look at this upgrade part with the 170 i worked on and the design concept is fundamentally flawed. It is still an improvement on the saito effort, but the holes into the crankcase are utterly pointless. The claim is they improve bottom end lubrication, but this isnt true as there is nothing forcing fuel forward into the case. Shoving fuel into the crankcase is daft concept anyway as fuel in the crankcase will not aid lubrication. Pure oil getting past the rings will lubricate better than oil diluted with a boatload of methanol, to say nothing of the corrosion issues. There will also be loss of differential pressure during the induction stroke due to increased volume in the induction system and this will reduce fuel draw. There are other issues too. Multiple direction changes for the incoming charge, used oil being recycled into the induction charge, no venting of residue from the crankcase... I was not at all impressed so made a much simpler job which worked very nicely. Although, bit of a lightbulb moment. If it has the MMM intake upgrade you need to make sure the crankcase vent is blocked. Failure to do so will result in a massive intake leak and all sorts of tuning and fuel flow problems. This might explain some of your problems if it has the mod and your breather is open. You will need to ask MMM about the spec of the engine to work out what it is you actually have. If it is in stock saito form the breather needs to be open.

Yikes that idle is rough as a badgers backside. Its only running on 1-2 cylinders at idle with the 3rd (likely no2 cylinder) only popping in and out from time to time. While this is partly due to the less than stellar induction and conrod geometry induced timing problems it should not be that lumpy. I recently rebuilt a saito 170r3 glow and it was pretty smooth running in its stock form and better still after i modded the intake. Even with a slight rich misfire on no2 cylinder the engine ran very smoothly so i would suggest this is running very rich still. You mention you keep adjusting the various needles but what procedure are you using to do it? The numbers of turns mean nothing (other than perhaps to signify a problem if they substantially differ from the saito specs) and the engine cannot be tuned this way. It can only be tuned while running and it should take only 2-3 minutes to set both needles if standard procedures are used.

First and foremost it is impossible to tune an engine by counting turns on a needle. It simply cannot be done that way so dont worry about the number of turns and just tune the engine using the standard procedure Martin has outlined until it runs correctly. The engine should also have been delivered back to you from MMM with the needles in their last running position. I would have left them alone and just fired up the engine, there was no need to move them. The type of carb used on that engine will not allow you to blow through it like a glow carb so i wouldnt not be concerned about that. It is also pumped so you may find you get no/low fuel flow while the pump is dry. Seeing no fuel flow you open the needle, the pump primes, and now you are slobbering rich as Martin describes. This should be easily identified by puffs of black smoke from the exhausts. A petrol engine this size will use a microscopic amount of fuel at idle so do not be surprised if the thing seems to be completely closed off. Stale fuel cannot be ruled out (unless you know its fresh), i would also be looking at the ignition side too and make sure all 3 sparks are in their correct places, ignition battery up to spec etc. My gut feeling though is the engine is simply mistuned, and its probable there are some procedural issues on your side leading to this poor state of tune. Petrol engines do not respond the same as glow and handle differently. Using glow procedures and knowledge when dealing with a petrol engine can be problematic. If you are able to shoot a video of the engine running and post it here it will be much easier to diagnose running and procedural issues.

I would check out the kit offerings from pegasus models. Many have slab sided balsa fuselages with foam core wings and deckings for the fuselage. They are usually quick to build and difficult to screw up as the wing is already set and building a banana is almost impossible. The fuselage is a simple box structure with the tail end of the fuselage sides pinched together. All you need to build one is a flat table and some squares (i use old CD cases due to availability and cost) for an accurate build. With all that said, the final choice of model will boil down to personal preference but also your current level of ability. There is no point building a lovely model which is beyond your current level. The choice of power plant is also helpful to know as it guides the size of the model. If you are able to provide these details we can probably offer more accurate recommendations.

I think the SB is for Sbus compatibility and there might be a higher voltage tolerance on the 3008. I have 2008's in plenty of models and they have worked very well for me.

What about a hard takeoff? I have had retract pins bent on takeoff after hitting a bump of some kind. On one occasion some mud accumulated and prevented smooth retraction as well.

If you didnt move the needle much between 20% and 10 its likely still pretty rich, and this may explain the idle issue. Make sure the main needle is tuned for peak performance and dont be shy leaning it off. Even if you go too far and it suffers a lean cut you wont damage anything.

What sort of idle rpm are you seeing slim? These little engines do not always run as slow as bigger ones. I think my 26fs is happy around 2500 but i cant remember off the top of my head.

The issue comes if they bind and continue to draw current. Then you can drain your flight battery before its time to land. As for the park fly micro retracts i guess you can run them without a separate power supply, but i wouldnt be doing it on anything big.

I wouldnt take the chance personally. While they are admittedly quite big the electric retracts in my sea fury draw masses of current and when testing them they would knock my futaba rx into failsafe about 50% of the time due to current spikes. On test i saw spikes over 6amps and constant draw around 1.5. I also tested their protection features and found they did not react very quickly to being jammed. In fact, they managed to crush my hand through one of the wing skins when i was a bit slow getting it out of the way, and this did not trip their protection features. In any event i would find space even in a small model to wedge a battery in there as its not worth the risk. That or i would simply use air.