Jon H

I am firmly in the no gyro camp myself. Just learn to fly the model and accept that all models are different and each has its own requirements. Its what keeps me interestd after 30+ years. if it was super easy and the models flew themselves it would get pretty boring

I have asked several times for the deep dive theory chat to be moved elsewhere. I am only posting this to deal with clear errors i do not want picked up as being potentially correct. The spray bar has one job, and it is literally to create the smallest fuel drops possible. This is aided by the pressure drop in the carb causing forced evaporation. This forced evaporation requires heat energy and this is stolen from the carb body etc which is why its cold. I am sure i covered this at school when i was about 13. Much of the fuel/air mixing is done within the cylinder so this assumption too is incorrect. Absolutely not. At about 8 years old we were all taught that water vapour in the air condenses into tiny water droplets as it cools and these are what we see as clouds/mist/fog etc. Methanol behaves no differently and any condensation of the vapour due to cooling will result in larger drops, not smaller. condensate will also tend to cling to the surface cooling it, not unlike the bathroom window after a shower, and then form even larger drops. This is far from ideal and the opposite of your claimed result. However, as we are not cooling the fuel mixture through the carb and the mixture is actually cooling the carb from within due to pressure drop/forced evaporation, this whole claim makes no sense as its completely backwards. The only condensation will be water on the outside of the carb, as this is being externally cooled. Yes, we can flood the combustion chamber and cause the engine to start. Some of the methanol will vaporise naturally and offer a mixture that will fire. The rest is blown out of the exhaust all over your arm. Unless the German book chappy never went to school i would say he is either straight up wrong, i have misunderstood, or the point he was trying to make has been lost in translation somewhere and misreported here causing the confusion. Hopefully its the latter, as the fundamental principals here is basic pre GCSE/O level school stuff and if the book really contains this as reported then thats pretty shocking. So i am done with this now and will be asking the mods to deal with any follow up posts on this subject. If a deep dive engine theory thread is required that can be set up elsewhere as the whole thing is being completely over thought. Its another 'leave it alone' moment, just fly it.

Dont admit defeat too early. My Dad's AM10 was swimming for goodness knows how long before it came free. If you want you could sent it to me and i can chuck it in the ultrasonic cleaner here at work. The fluid we use teaches castor a lesson with no problems.

nah its fine. The whole theory section is technically off topic. A little is fine, but we are getting too far into the weeds now

more info here https://www.enginelabs.com/news/f1-tech-what-is-turbulent-jet-ignition/ However, we should probably start an engine theory thread to deal with all this as we are well of base now.

If you are asking what i think you are (shimming high nitro engines that knock) then there is more to it than just the fuel. The more fuel you are burning the more the compression increases as the fuel is incompressible so you need to shim it to bring the comp down a bit. I believe top fuel dragsters run almost on the verge of hydraulic lock to get maximum power. If i understand this correctly, You do not want the fuel to condensate into drops. You want the finest vapour you can get mixed well with air, so i am a bit confused by this. Unless i am misunderstanding the wording here it makes no sense at all.

anything after 92. All of the discontinued 75's etc should stick with 15

I was under the impression that only one end/side/corner actually fell down. Although i must admit, there are no photos i can find showing a wide angle to see the whole thing.

Why are you claiming on your own insurance? This would be a no fault claim as the car was just minding its own business as you sunned yourself half the world away. so it should all be on the other parties insurance. I suppose the only difficult part is working out who is responsible.

We are in danger of falling too far down the rabbit hole here and are into the realms of personal research for the individual. Although discussing cars, this offers a simple overview of combustion chamber types http://www.secondchancegarage.com/public/585.cfm Saito use hemi, Laser and Enya use wedge, OS and its clones use bathtub. There is more to the story though with bore/stroke ratio, valve size, carb size, valve timing, valve lift, valve duration, pumping losses, squish area....How they all interact is not always predictable and our 180 for example has a really high compression ratio, but other factors mean its still a fairly laid back engine. Also what prop are you using? Revving its rod off will warm it up a treat, but using a 2 foot paddle will also have an impact. If were were designing a race engine this would all make a difference, but we are playing with toy aeroplanes and none of this really matters. If you compare a saito 82, laser 80, and OS81, all of which use different figures for everything listed above, and you run them on the same prop and same fuel its doubtful they will perform by more than a few % different despite all these major differences. I did this with an OS, Enya and Laser 155 and there was very little to choose between them. The winner was dictated by the specific prop it was running and how that worked with that engine. Run 10 different props and each engine would score a few wins, a few 2nd places and a few 3rds. The Laser tended to perform best on bigger props, and the Enya best on smaller props, but with only a few hundred rpm between them on any prop did it matter much? Not really. Its not like changing from one brand to another would transform the performance of the model. Also the Enya and Laser are the most similar in terms of design concept and yet they performed the furthest apart. While i applaud any efforts to learn more about the hobby and understand the granular detail of certain subjects, there can be a tendency to overthink it if you arent too careful. ehhhh not exactly. Knocking is pre ignition, ie the fuel charge fires too early in the rotation of the engine. The cause could be heat, the plug, the load on the engine, the rpm of the engine, many factors play a part and blanket statements are not really possible.

All glow engines will run on methanol and oil, you do not need more than that. Years ago I used straight fuel in some ASP 52 2 strokes i had and they ran just fine. Nitro is included to increase power and make needle settings less critical. This happens as the nitro releases oxygen as it is burned, so you open the needle to allow more fuel in to keep the mixture balanced. This is why high nitro engines guzzle fuel like it is going out of style. Anyway, the larger opening of the needle (number of turns) means that a tuning error of a click or two is a smaller percentage of the whole and so the tuning is less critical. The effect of the nitro also makes the 'optimum' tuning range broader in the first place. Much of the above is over simplified, but i dont have all day or a degree in chemistry to really drill down into it 🙂 In the case of saito part of their request for high nitro is so they can use the fuel as an upper cylinder coolant before they burn it. Spill glow fuel on your hand and its cold, touch the carby of your running 4 stroke and it will also be cold. WWII aircraft engines used water methanol injection to cool charge air, etc. This all matters as the ignition timing of the fuel charge is governed by a balance of things like compression ratio, plug temperature, charge temperature etc. if you increase the temperature of the plug or charge, you advance the ignition. Higher comp ratios increase charge temperature and this can cause knocking when the mixture is leaned for peak power, so you have to cool the thing down. I know some have shimmed their saito engines to reduce the compression ratio and they run very well on straight fuel and use much less of it. All that said, i run my saito 45's on 5% and they are no bother. I test ran a new saito 82 for someone the other day and it ran fine on 5%. It wouldnt hold full power long as it heated up and knocked, but it was new so cant hold that against it too much. I also used to own a saito 450r3 radial and saw the same or increased performance on 5% as rcu forum members in the US running 20%. Mine would also idle fine without glow support but theirs would not. Running lower nitro means the engine will run hotter at idle which helps keep the plug alight. Also with the engine at idle and a rich mix there is lots of the fuel soaking heat out of the engine causing unreliability. To summarise. All standard 2 and 4 stroke engines from any brand use 5% nitro and 15% synth oil. Its literally the only fuel in the world as far as i care. The exceptions in fixed wing are things like ducted fan, pylon or other highly tuned engines. or tiny engines like the old cox motors, or YS supercharged engines. Heli's, cars, boats etc again there are different operational requirements so they fuel requirement changes to match. The primary reason for the 'high nitro better' debate is because slow run needles are left sad and alone having never been adjusted from the factory setting. You must adjust your slow running needle as it governs the mixture up to around half throttle. They are deliberately set very rich from the factory as most manufacturers do not test run their engines and they set them rich to guarantee an engine will start. If you do not lean it off (sometimes several turns) the engine will be too rich and run badly. Adding nitro 'fixes' the problem as the mixture is closer to being right, but its not fixed it really, its just tuned better. The same or better result would have been possible with 5%. Oh and it wouldnt be one of my posts without mentioning tank placement. Top of the tank in line with the centre of the carb. Get that wrong and the engine will be impossible to tune correctly anyway.

Am i reading that right? The building is unsafe so they are not allowing the removal of even undamaged cars? That seems rather stupid. It must be possible to shore up sections adjacent to the fire and get the undamaged cars out.

Synthetic is fine and the recommended recipe is: 15% oil 30% ether 2% ipn or 2ehn balance as paraffin/kerosene etc Modern synthetic oil is superior to castor and even PAW recommend a fuel with a synthetic alternative now.

not much difference between them

i was wondering about that

I think the 'warplane' is a db models old bill, and the blue/yellow model a db mascot trainer. Not sure about the others.

Why would you want to collect a battered old heap? Makes no sense.

But they wont post stuff. Makes it a waste of time in my view. As for the 180v, bin it and buy the 200 they have on there instead. Its still old, but at least its still supported.

yep, they got it from cranfield if i recall. The issue is the only have the one!

No. Stop. Sintered bronze does not respond well to impact loads and a conrod will see significant impact load. Your motor will only see rotational load, which sintered bushes are good at. So, we are going to try this one last time before i completely loose my cool. Leave it alone. You risk causing greater damage by doing a bodge job repair with the wrong materials and tools. Is .5mm too much? Do you know what the clearance was when it was made? 90's have soft EN24 cranks and ran higher big end clearance than current engines. Exactly what that was i dont know, its not relevant in my day to day work so will have to look it up, but the point is it might not be as far out of spec as you think. In any case, some big ends of that era do not have oil holes and instead have a helical oil way turned into the bush itself. Will you be able to recrate that? And the bronze you are getting. What is it? Ali bronze? Phosphor? Silicon..? They are not all the same and not all of them are suitable. Even if you source the correct material its really not a good plan without the required tooling and knowledge so stop guessing, put it all back together, and leave it alone. You asked my advice as the manufacturer and that is it. Leave it alone.

Really shows it size when it dwarfs the mustang taxing in front of it!

Apparently Merlin engines and parts are quite abundant. This includes new old stock engines still inhibited since manufacture and never run a day in their lives. Less prolific engines are a problem though. The Typhoon restoration mob in Canada have been very quiet about their engine plans, but they have two partial sabre engines (one crashed one cutaway) and i think their plan is to just build a new engine from scratch. This makes total sense to me given modern materials and processes are so much better. If they can do it why not make 2...or 3, or 10...Kermit Weeks has a MkV Tempest airframe and 2 original Sabres. The group who just fixed up the MkII here have a MkV in storage too. It could be done. As i have said before, i think it is getting to the point where the regulators need to have a chat and authorise the manufacture of new engines/engine parts for these aircraft. Most warbird accidents these days are down to engine failure, often at low altitude due to their airshow flying nature, so it has to be a bonus for safety to have a newly manufactured engine fitted made with modern materials and processes. I know some will cry about provenance, but with very few exceptions most warbirds flying today are more or less complete new builds with a name tag riveted to them at the end anyway. And as Martin says, i want to see/hear a Sabre engine flying about the place. I dont care if its an original one or a new one. Its still a sabre and i still want it.

Or not? If the job is not done properly you risk killing the engine today. Brass will not be satisfactory and as it wears it will shed bits of itself all over the place causing damage to other components. I cant understand why leaving it alone is not an option. It works, leave it alone!

I think there is another somewhere too...NZ maybe? I am sure there were 3 MkII's on the go but this one is the only one with the correct engine. In any case, its a monster of thing. The longer wing vs the sea fury is very apparent.

What we have all been waiting for