Jon H

You can learn on any model you like to be fair. If you wanted, you could learn using a 50 grand jet but i wouldnt recommend it. For me the most important factor is the support and training you are going to receive. Will you be going it alone in a park or friendly farmers field? Or are you going to join a club and be taught using a buddy box and all that? I would recommend the latter, and with that you can skip some of the more basic models as the instructor will get the thing in the air and then hand it over to you. Once you are suitably terrified, he will land it for you. As your skills improve you take on these other aspects of the flight. If you go it alone you are at the helm from the first instant and might even manage to crash before you have left the ground. If the model is a hand launched affair then you are quite literally throwing it into the unknown. As a result you have to pick an extremely basic/stable model which will ultimately not last long as you will out grow its capabilities quite fast...assuming it lives that long as takeoff/hand launch related crashes could wipe it out before you get anywhere. This is why i would strongly recommend a club. I would avoid twins of any flavour for the reasons already mentioned by the others, but the high wing/low wing argument is a little fuzzy these days. if someone showed up asking me to train them, and had the same 82inch span 150 4 stroke powered Spacewalker that i have it would be no bother as the thing is a big floaty pussycat which (due to its size) is very easy to see at a distance and not too phased by the wind. Given you are looking for something smaller i am not suggesting you rush out an buy one, just that blanketing all low wing models as difficult to learn with is not an accurate statement as many are very well behaved. Cap232 however, or a Spitfire, not recommended!

Ah yes well its a complicated attempt to save my SCASP 400 radial. One of its main issues is the valves. Some clown decided it would be fun to use valves made from cheese. And not a nice hard cheddar either, more of a baked camembert. In any case, the valves wear at an alarming rate and loose their seal after about 2 hours of running. I am bored of fixing them, so i thought 'would laser valves fit?' They do, the heads are not a bad size and they seal well, but the stems are too short for the existing valve guide and spring setup. So, what if i ream the heads and fit Laser valve guides, valves, springs etc...would it work? can i achieve the required accuracy? This is why i plan to experiment with a busted head before i mangle the ones on the engine. If i can fit the new valves, do i then need to make new rockers or can i shorten the rocker shaft mount post in the head? I also need to fix the rear crank bearing mounting plate as the bearing just falls out. I need to fix the front housing as the front bearing also just falls out, and....i forget, there is something else i need to do but cant remember what it is. Either way, there is much to do. EDIT. Wait, i remember. Make new piston rings and/or, see if i can make new liners and fit current Laser pistons and rings to increase capacity and performance.

both sound perfectly fine for my experiment. can you please send them to me at laser? its easier as someone is always around to receive it. Do i owe you anything?

Thanks ED, an os91 head would be perfect if you still have it

Computer says no to your video 😞

Does anyone have a busted ASP 70, 80 or 90 4 stroke cylinder head kicking around? If the exhaust port is ruined or something like that i would be interested in it for a little experiment. I dont want to mangle a good head if my experiment fails so if there is a busted one kicking around that isnt needed please let me know

i dont think i can remember the last time i saw any engine at any club i have flown at throw a prop. Clearly you chaps are doing something wrong if you are throwing props that regularly. Like i said, i havent had one escape in probably 20 years or more and none of my engines have locknuts even. I do however keep an eye on my prop nuts being tight as many are wood and this can alter with conditions, but this is just normal maintenance. A flooded engine may have its prop spun off by the starter, but that's your own fault for flooding it and it can happen to a 2 stroke just as easily (more so in fact). As for the dirt in the fuel line, why is your fuel dirty? Even so, the prop should not fly off as the engine will simply suffer a lean cut and stop. As for the saito inlet kits, one came with the 170 i was to working on and i didnt use it. The design was fundamentally flawed and would not do what it was advertised to do. It would have had a negative impact on the engine in a number of ways and i would not recommend them. Dont get me wrong, the saito effort is not spectacular either, but the so called upgrade is not well thought out at all. I dont care for either fuel but absolutely stick to the opti given the two fuels you have available. Going forward though i would try a lower nitro fuel and see how you get on. I ran the 170 on the 5/15 fuel i use in everything and it would idle happily just over 2000rpm without any glow support. I left it like that for a few minutes and it still throttled up on all 3 so i considered that a win. some years ago i had a 450r3 and ran it on 5 nitro with 15 synthetic and 2 castor (it was before i saw the light). I was able to match or exceed the performance of chaps in the US using 20 and 30% nitro and i didnt need the glow support they did to keep an idle. These radials are not that responsive to nitro so it will not offer the advantage it might in another type of engine. High nitro fuels demand a greater physical quantity of fuel in the engine and this cools the cylinders making a flame out more likely. The lower nitro fuel will allow the engine to remain hotter at idle and this will aid in keeping the glow plugs alight. As i have mentioned before i run my OS 4 cylinder using the 5/15 fuel and have not lost a cylinder on it in the 3 or 4 years i have been flying it, and my ASP 160 twin uses the same juice and gives no flame out problems either.

The one labelled FA45 is a MKII and was introduced around 1988. The other one is a bit of a crossover of MkI crankcase with the later monolithic cylinder so i would put it a few years earlier. Great little engines. I have 3 of them and while not massively powerful they are dependable, quiet and economical. The later 45 specials up the power, but are not quite as nice when it comes to the handling.

Are they? Not had any engine throw a prop on me since about 2007, and even then it was my fault! Martin your engine sounds pretty good but i would take the time to make sure your slow run needle is as lean as possible. Do this with the glow support off. It will not cure the no2 issue, but it will help. I recently did some mods to a saito 170 radial and was able to make changes to the induction which improved the engine a fair amount. I also confirmed my suspicion that a geometry issue with the master/slave conrods causes each cylinder to have slightly different cam timing which is why they all run differently. I did have some other ideas for improvement, including an air bleed for the no2 cylinder, but it ran well enough and was totally reliable without glow support so i just left it alone. As for the cooling, i would leave it for now. The cooling will not work very efficiently on the ground as its lacking the slipstream it will see in the air. Once in the sky it should work much better.

Normally i would agree, but the budget range from simplybearings have proven perfectly acceptable in a number of engines i have refurbed over the years. That said, 6001 and 608's are hardly expensive even from a brand name so its not really an issue in this case

I suspect you are outside of the tuning range of the engine with that fuel. Change the fuel as 20% nitro will not be helping you at all. The high nitro fuel will require the main needle to be opened further to correct the mixture. Its likely you are simply beyond the adjustment range of the air bleed screw and the engine is just drowning. It wont manifest when upright as the fuel is able to drip out of the carb but inverted it just floods the intake. The excess of fuel will also over cool the engine at idle causing a flameout. The high nitro might also be leading to the engine running excessively rich and this will make things worse as well. The OS blurb suggests a 5% nitro and 15% nitro blend, each with 20% castor 🤢 I would reset the airbleed to half open, tip some 5% nitro 15% synth oil fuel into it and give that a go. it will raise the engine's operating temperature and bring the thing back into its tuning window. I have not tried it inverted admittedly, but my FS26 is very happy on this brew as is the battered old fs40 i rebuilt some time ago. that little 40 gets absolutely thrashed in my seagull challenger and is quite happy with all of my abuse.

Well i was working on the basis that my 'modellers' category covered your first two points, club and youtube 'experts' are covered by point 3, and the last...well, i will leave it to your imagination 😉

I closed the laser tech thread as it was too much of a battle. Every comment i made was argued to the ends of the earth and it just became too tiresome. However, my top 5 list of common problems would be something like this 1. Modellers/Club 'experts'/Forum 'experts'/Youtube 'experts' 5.Tank placement

Yea absolutely. I used a small 4ah motorbike battery here at work and it worked fine. Alas its dead now. Apparently leaving it hooked up to the charger but having the charger off at the wall drained it stone dead. oops. My 6s 3000mah lipo is good for probably 6 months of starts if i used it every weekend. Its why i keep killing my starter lipos. they last so long i forget to charge them regularly and kill the cells.

Yea most likely. Not all brass tube is created equal either and some is full of impurities that allow the methanol to really get into the material and do damage. Generally is fine as long as they dont stay submerged all the time so drain your tanks when finished.

Certainly is and google provided this handy equation showing water as the largest exhaust product. Methanol Oxygen Carbon dioxide Water 2CH3OH(l) + 3O2(g) --> 2CO2(g) + 4H2O(g) This does assume perfect combustion though, and we arent going to achieve that very often.

I use one of these (or similar) https://sussex-model-centre.co.uk/products/maxi-fuel-filter but its a 6 of one half dozen of another debate which specific filter is best

I have had half a dozen twins over the years and all of them had the engines dead straight. None of them caused any issues and nor has prop rotation. In fact these days i mount all of my engines dead straight in all models and just get on with it. The side trust argument is a hangover from the old days of freeflight where the model had to be trimmed to fly on its own. outside of a few specific use cases its more or less irrelevant for RC flight. We have a tall waggly thing on the tail to keep the model straight and i just use that. Also remember that being electric is not a guarantee that you will not have to deal with thrust asymmetry. Variations in components can still cause issues and you can still have failures of one kind or another causing an engine failure. Twin's glide like stones so you must maintain your airspeed if you do loose a motor. If you dont, its all over.

This is a good shout. I use a course filter as the pickup to strain out big bits like grass which may fall in the bottle. I then use a fine filter at the other end and plug that into the model for filling. The model has no filters on it as the fuel has already been double filtered before making it to the tank. By the way, which engine have you actually got in the model?

I think there is an echo in here John 😉

12v and a 3s (maybe 4s if you need more spice) lipo would work fine. I use a 6s on my beefy 24v starter and while i do occasionally weld the switch on, its rare. The trick is to make sure the engine is wound back to compression so you do not stall the starter. Stalling the starter will weld the switch together if you have the high current capability of a lipo. A small motorbike starter battery can also work well but is obviously heavier. If all else fails a well set up engine will hand start with ease and all you need is a foot long offcut from a broom handle. Beyond that a manual fuel pump is fine. I have used a prolux fast fueller hand pump for the last 10 years or so here at work and its not dead yet. For glow one of those battery on a stick types is recommended assuming the glow plug is easy to access. This is similar to the ones i use here at work and will probably be man enough for 100 starts or more. https://nexusmodels.co.uk/collections/glow-starters-clips/products/j-perkins-glo-start-clip-l-2500mah-nimh-charger-3pin-5508216

Yes absolutely. Adequate safety precautions must be taken as its deadly stuff

As i have posted before i am testing some 2k clear intended for use on custom painted motorbikes. Its half the price of the modelling equivalent and my test model is looking good a year into the test, which is much better than the guild fuel proofer originally used as this lasted about a week before giving up the ghost.

I have also come to the conclusion that you need a 2 part paint to resist glow fuel. Nothing else seems to work at all.

Having another go at listing my partially built DB Spitfire for sale with a better photo. Condition is the same as in the OP. I was looking for £250, but am keen to shift it so open to sensible offers.