Jon H

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.

all servo/electric retracts need an isolated power supply. A dual battery setup using a modified y lead is simple and effective.

2008-2011 for my model shop service. I always tried to give good advice, much to the annoyance of my boss on occasion. A customer wanted to buy an ASM Hercules (100 inch, 4x 30 4 strokes) and i got in trouble for recommending standard 3kg servos for it as it 'needed' much more powerful digital servos as its a big model. My argument was the size of the model is irrelevant. The model might be big but the control surfaces are small, its pretty slow and generally needs to just wander round the sky looking fat. As time went on i ended up with one myself and it flew fine with standard gear in it. I would also get in trouble for spending time with customers buying nitro cars. If i sold one i would tell them to charge up all the gear and come back the next day. I would show them how to start it and not break the pullstart. I was told this was a waste of time (costing money) and we would make money on selling pullstarts when they broke them. I considered this short sighted as it wont take long to turn a customer off a product if they keep breaking a part and dont know why. Especially when the repair cost was nearly 20 quid a go and an hours work. I worked on the basis that the time spent showing the kid (usually father and son bought the cars) how to do it was not only the right thing to do, but also good for the business as said kid would have friends, and those friends would want a new toy as well. Sure enough, many times friends/brothers/cousins also wanted a car so they could race and it turned out my 'waste of time' was actually time well spent. Didnt stop me getting in trouble though. At laser i have turned many a customer away or onto a cheaper engine as they one they selected was unsuitable. One in particular i recall was a chap wanting to fit our 70 into a flair se5a as his club mates told him the 40 4 stroke on the plan would never be enough. They were wrong, as i have flown the same model using a 52 and it had massive amounts of reserve power. I recommended a saito 45, but they were discontinued as were the 50's and the OS56 was crazy money. He bought a saito 56 in the end and called me back after the models first flight to report that it flew like a pitts special at full power and he was extremely glad he never bought the 70. He then told me about his next project and asked which engine i would recommend. I cant recall the details of that project, but he bought an engine and keeps coming back as, in his own words, he 'values honest advice'. Again though, to give shops some leeway margins on big ticket items like engines, radio and models are pants and that sort of forces them to flog other stuff just to break even. I know shops would be much happier if we all went back to building kits as a tube of glue and 3 sheets of balsa probably has more margin on it than a mid range radio. Anyway, we digress.

In fairness, spektrum rx's are (or at least were) vulnerable on 4.8v packs even using standard servos. I worked at a model shop and the advice we gave about using 6v packs came from Horizon themselves. While it is not unheard of for model shops to flog you something more expensive than you need we were under instruction to do it in this case. There clearly was an issue as they sold that plug in capacitor thing to help guard against voltage drops. Admittedly this was all 10-15 years ago and a great many things have changed since then so it may not be true today. My only spektrum rx's have operated off of bec's in electric models so i have no first hand experience with them on a battery. All of my futaba 2.4 rx's have been fine on 4.8v so i have no worry there. A club mate had some hitec 2.4 rx's that flat out refused to work on 4.8v for some reason, but i have a sample size of only 3 so that is hardly conclusive.

I think cell death in nimh and nicad packs is an overstated problem these days. In the old days of trickle charging and nicad memory etc it was much more of an issue that it is today with a peak charger monitoring what is going on. The memory issue is absolutely the root cause of the issue Cuban points out where just topping the thing up every week didnt do it any favours at all. My batteries are all due a cycle to check their health and i tend to do this every year (missed it last year as i hardly went flying at all), but just keeping an eye on things is well worth while. My Sea Fury battery was detected as faulty as it would discharge more than all its mates in other models when stored over winter giving me a red light on the battery checker when all of the others were still in the low end of the green. Still, this battery had on two occasions been run stone dead flat as the switch got bumped and the model ran flat, before remaining so for weeks at a time. This likely killed the cells so that battery has a knot tied in its lead to mark it as non airworthy and i use it for things like bench work and/or driving electric retracts. I have never had a battery fail in flight and i am still using some packs which are more than a decade old. I delta peak them in the morning before i head out to the field and make a mental note of the time taken to recharge. In regular use i know that i have time to put it on, have breakfast or whatever and then it should be ready in X amount of time. if not, or it peaked early, there might be an issue that needs investigation. Dating batteries is a good idea, and i put that sort of thing under generally paying attention to your gear and just being attentive. It still surprises me that people have absolutely no idea what their gear is, when they last did maintenance (if they ever do any), what fuel they have, what prop etc. Just knowing your gear inside and out is more than half the battle. Oh and i do not consider fixing something broken as doing maintenance. Maintenance is preventative work to stop something before it happens. Fixing a broken thing after its failed is a repair.

huh, thats a new one. i question the logic of using a battery to charge a battery mind you. In any event, as ED says its all about the charge rate. As you have some fancy chargers for you electric gear, you can always snip the end off the USB cable and just make a lead to delta peak it off your existing gear. As for the force required, that will loosen as you use the glow clip and it 'runs in'. Be sure to pull the outer back to allow the inner part to expand around the plug.

I personally use Nimh as they are quick, cheap, and simple. I am also not a fan of burying lithium based batteries in foam and then whacking them on charge. A lipo with a regulator also has more points of failure within the system so is technically less reliable. I use 4.8v 1200-2200mah for my smaller stuff (up to about 70 inch sport/scale) and 6v 3000-3300mah for my big scale stuff. In your mascot i would expect a 1200mah battery to be good for at at least 20, and more likely 30 flights of the duration you mention. As Frank points out, we used to use 6 and 700mah nicads and not think anything of it. Modern 2.4ghz radio use less power than the old 35 meg stuff as well and i noticed this on a model i swapped from 35 to 2.4. As with many things, there is a perception that 'bigger number better'. Where a 40 2 stroke used to do fine we now use a 55. Where a 3kg torque servo used to do we now use a 9kg digital for some reason. 5% nitro was fine but we now use 10 or 15. Batteries are the same. If 700mah is good 3000mah is better, 6v is better than 4.8, so a lipo or life at 7.4v or whatever is better? I dont really subscribe to that sort of thinking myself and select the minimum spec equipment that will do the job and have a required margin so it is not pushed to its limits. Buying bigger number equipment often comes with a bigger number price, and this is not ideal. Clearly you can buy a bigger number piece of equipment at a low bangood price, but i have seen more than a few models bite the dust as their cheap and nasty gear let them down. In the case of the DB Mascot, i would use bog standard 3kg servos, a 4.8v1200 nimh battery and a 35 or 40 2 stroke. Even an old 35fp plain bearing engine would be more than enough. It would be most civilised and have more than enough performance for a little fun.

USB glowplug driver?? what on earth did you buy?

Thanks for the offers guys. ED's heads have landed, complete with an 8 legged friend who was determined to try and crawl all over me. I need to remove one head from the radial to check they are close enough in design for my experimentation and i will go from there.

Considered it, but it would put the carb and exhaust ports on the front of the engine and i also dont think i can get away with 'loosing' that many parts 😉

Probably not soon. I have quite alot on my plate at the moment. No rush, and thanks for the help.

Not enough that a beginner would notice, but it can save you a few busted propellers.