Tony Iannucelli

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Like the guy named SpeedRacer, I'm having some fun and learning things on here. I try to never criticize anyone, and I won't start now. I think we all have a great hobby going for us, and there's no reason to spoil it with inappropriate comments. Much better to give opinions, especially opinions that we know (or think) are true based on experience.

Like Speed Racer, I've been in R/C for a long time, 1972 to be exact. We moved to Florida 12 years ago, and I'm in a great club with 140 guys in it and we fly 12 months. We have three recent National Champions in U-Control as members. We also have some truly expert airplane 3D fliers and several guys that know everything you could want to know about engines of all kinds. We have several electric flier experts. We have a guy who wrote a current best seller on R/C helicopters and writes a regular column for a national magazine. I have learned a lot from all of them and continue to do so. We are all friendly, and no one is trying to one-up the next guy. Truly a rare thing from what I have experienced in many other clubs. That being said referring to what is above on this string....

I can't think of anyone who shuts off the fuel supply to their engine using hemostats any more. I'm sure it works, but a small clip or fuel valve is a much better choice I think. So is shutting off using the transmitter, a much easier choice with cowled engines. Electric starters can hurt your equipment sometimes. We've all seen them slip off spinners while being used. We've all seen guys grinding away with them when it's obvious there's something else preventing their engine from starting. Helicopters sometimes take a little longer to start. Best to find out why before you grind away. Even better, with planes, learn what your engine likes, and hand start it. Believe it or not, it's easier and with the correct technique, it's safer. Chicken sticks are the worst. I can almost always reverse twirl/spin start my engines, mostly OS, inverted, on the side, or upright. It took some practice, but my hands never touch the prop and I can move them off the engine almost instantly. No bruises yet, in decades. And OS engines start with a couple of flips. Hand starting is the easiest way to avoid hydro locks.

When I started in helicopters in the early 80s we were using mostly Schluters made of metal (like Erector sets) with JR120 gyros and hand made blades. We were happy to hover and do flyarounds. Mike Mas, John Gorham, and the Japanese brought us to a more enlightened place, and of course the equipment got better. The Hirobo Shuttle brought thousands of new fliers into the hobby, and the gyros kept getting better. We started using header tanks mounted just below the carb. Some people thought they were to keep the fuel head in that prime position we've been talking about, just under the carb. They weren't. The header tank just helped with fuel foaming and it helped break up bubbles to prevent flameouts. That's all. There's a lot of vibration in all helicopters and fuel foams if the issue isn't addressed. Tank placement in helicopters is very limited. Fortunately the 'natural' position for them is about where there should be, at the bottom of the frame. There have been a lot of attempts at solving helicopter engine variances; running cooler with higher oil content to offset higher nitro (creates heat but more power), pumped engines, YS 'pressure regulated' engines, and now just brute force electric motor power. Actually electrics circumvent the need to fiddle with nitro engines in helis. I suspect it's a main reason they are so popular. Don't like the short flight times myself, but I'm too old and slow for any attempts at 3D now. Like many of you, I am a terror on the simulators however. As a point in argument, I had a DF Violett Sport Shark jet in 1987-89. We used a header tank in that plane because the fuel head in the saddle tanks was well above the engine. I don't know if that's why it worked, but it was sold that way. It did work.

Pumped engines solve a lot of problems with tank placement but cause other problems. Most OS engines start at around 2-21/2 turns open on the main. OS pumped engines sometimes flood at those settings. They work better at 1 1/8 turn open. Pumps have been the answer for pattern flying in my recollection and the Walbro pumps seem to be the answer for radical 3D flying with gassers from observation. We used to mount the tanks at the CG in pattern ships so balance wasn't effected as the tanks emptied. We also had to have tank position very high in the planes because of trike gear retracts, and the nose gear needed a place to go. Most pattern ships didn't have enclosed engines, so clipping the fuel lines with closepins and hemostats were used back in the 80s. But the OS.61pumped SF engines were king in my little word, and still are.

The subject here is supposed to be tank placement. Assuming we are all sport fliers and not experts as has been pointed out, I would finally suggest that a bit high or a bit low might not be noticed by most of us flying our loops, eights, stall turns, and other basic maneuvers. True, the engine RPM is affected, but not enough to matter IF you have the needles set properly, use clean fuel, and the correct prop. Just saying what works for most of us in my club, even the best and most expert of all of us.

CafeenMan

One time I thought my fuel lines my be kinked or that the clunk went forward in the tank and kinked the line inside. So I disconnected the fuel line and blew into one not thinking about the fact there was fuel in the tank.

Or course I blew into the pressure line and sent plenty of raw fuel into my face and one eye. That wasn't very pleasant.

Another time the vent line was kinked and I blew into the feed line which pressurized the tank and when I stopped blowing I got a mouthful of fuel.

There are those times when you know something bad can happen and you think it through in advance to prevent things like that. Other times it never occurs to me that something bad might happen and I just get to it.

Tony Iannucelli

My Feedback: (193)

Some pictures referencing my previous post.

carl24bpool

thanks john.

Refuelling down the carb line seems common sense to me and works fine.

carl24bpool

Toni,

can you advise more on the reverse twirl / spin start?

i always try using a chicken stick first but on the very first start intend to always need the electric starter.

Does anyone have a good guide to hand starting properly. I know you just spin the prop but there must be finer detail for getting a first flip start. Ive tried hand stating the Irvine 40 on my trainer which is upright and even that can take 30 flips or more to get it going.

JohnBuckner

My Feedback: (1)

Carl here is a vidio demonstrating the reverse bump start:

http://www.youtube.com/watch?v=LyvLW...h_0PWTkXPcXnWA

It does require the perfect state of prime and some engines will be easier than others so it may or may not be useful to you. I reccomend to most new folks to stay with a starter at first. And of course if using an inverted two stroke especially with an installation that may demostrate syphoning it neccessary to check for hydrolock manually every time before applying that starter.

John

speedracerntrixie

My Feedback: (29)

Carl, myself I call this a " bump start ". And use it on all 2 stroke glow engines. Open to full throttle, with finger over the carb intake flip around 3 to 4 times. On the first start of the day it may take more flips. You will get a feel for when the engine gets fuel into it. Without your finger over the carb flip a few more times. Again you will feel that the engine is wet. Reduce power to a medium fast idle with the glow igniter on with your index and middle finger on top of the spinner and thumb on the bottom give the spinner a flick clockwise. If the engine has enough fuel it will fire and run the correct direction. If it does not fire then you either have gotten it too wet or not wet enough and have to adjust your priming process to suit. If it fires but is running backwards you have over primed it just a tad. After a few attempts anyone can get to the point of starting this way on the first bump. This however does not work on a hot engine, you need to allow the engine to cool some between flights. In 4 seasons of racing with a modded Rossi .45 I have had to pick up my starter about 6 times.

Tony Iannucelli

My Feedback: (193)

Hi Carl. Not sure if I can articulate how to do it. Let's start by saying I use OS 8 glow plugs, 20 percent nitro and 20 percent synthetic oil fuel, and the proper propellers. Being from the UK, you might not use high nitro fuel, but it might not matter anyway.

Engines run with a mix of fuel, spark, and air as you know. Having the right prime of fuel and a hot glow igniter before attempting to start is important to your success. I tend to over prime my four strokes, almost flooding them sometimes. They like to be "wet", and it makes reverse starting easy. On the two strokes I try to see the fuel in the line entering the carb, then give the prop a few more manual counter clockwise turns to be sure the fuel is getting into the engine. You can often hear when an engine is primed enough sometimes.

Set the prop on compression so that it is parallel to the ground or just slightly more at say two o'clock and eight. Turn the prop backwards so the compression is on the left side, or eight o'clock position.

I put my right index finger and middle finger on the top of the prop and spinner on the right side. I put my thumb on the bottom of the the spinner on the left side. I then twirl the prop backwards by spinning it to the right, hard. Instead of flipping the prop in the normal counter clockwise direction you are flipping it to the right, clockwise. If the mix is correct it will kick back and start straightaway. The engine will tell you if the mix is wrong by either starting backwards or not at all. If it does start backwards, just blip the throttle. It may reverse and start running properly, or quit. Either way. Try again. If you've flooded it, try flipping on the lowest throttle setting. Some engines like cc and some like clockwise when flooded. It won't take long to learn which one it likes. My inverted four stroke installations require little or no priming, side mounted might take a few flips.

Learning the proper procedure may take a bit of time, but it's well worth learning. Practice spinning the prop, that's the tricky part. Practice in your shop, with no intention of starting the engine, just learning to spin it clockwise until you can get it to kickback with some authority. Oh yeah, don't forget to withdraw your hand away from the prop when you twirl it! And don't forget this is for nitro only. Gasoline is a different protocol.

Your flying buds will be amazed with your new skill. Good luck.

HighPlains

My Feedback: (1)

I'm always amazed at the arguments on RCU.

With 50 years of modeling experience, and an engineering degree and I am convinced that tank height is very important in making an engine run well in both inside and outside maneuvers. But if you enjoy just flying around upright, then it matters less.

Best choice for all, just go electric and leave glow fuel to those that watched men walking on the moon.

carl24bpool

Hey buddy,

i don't think I could ever go over to electric permanently.

I love engines. In the uk people like me are called petrol heads.

tuning and running an engine is part of the hobby for me. I love how such a small piece of engineering can produce so much power. I also love the noise compared to a brushless motor. Flying past yourself at full speed o. A nitro is a lovely noise.

Each to their own I suppose.

not to say I wouldn't like an electric for quick and easy half hour sessions but I'll always have nitro as my main method of drive.

byrne1157

I have 2 cents I'm willing to throw in this pot. I've been flying for 4 years now, got a late start at this, but I do have a degree in internal combustion engines and have been tuning from single to 8 cylinder engines, both 2stroke and 4-stroke all my life, so this is a great thread for me to read, and maybe contribute to. Seems to me, the fuel level, pickup tube (clunk) positioning is the cause of all the hoopla. I have a few glow engines, both 2 and 4 strokes, in my airplanes, both upright, and inverted. I learned after fueling my first inverted engine airplane, (an extra 300s), that it did indeed have the problem of siphoning my fuel both into the engine, and out on the run-up stand. I quickly cleared the hydrolock, and started the engine for a successful flight. After the flight, I immediately de-fueled the airplane untill my next flight. This time, I did my pre-flight in a different order. the last thing I did before starting the engine was to fuel it.I gave it no time to siphon any more fuel than was needed to prime it. I have the feeling that the designers knew what they were doing concerning fuel tank placement. This is only my opinion. Proper fuel tank placement is that which allows the best overall performance when the airplane is flown in it's performance envelope. Any other problems arise when the builder installs either the tank, fuel tubing, or engine inconsistant with the manufacturer's instructions. I have found muffler pressure to be sufficient to give the fuel the extra push needed to give the engine the fuel it needs, no matter how I fly the airplane, as long as I fly it within it's envelope.
But, I could be wrong,

carl24bpool

Thanks john. I've done this before not knowing but I was spinning it the wrong way so it would fire backwards. Now I know I'll give this a try.

Thanks again to everyone else. My simple question turned into a great thread for others to use.

i have to say that from what I've read the position must have an effect on running. I don't fly level. I like to throw my pc-9 around quite a lot with lots of g manoeuvres and inverted flight. I think for that reason I need to try and get the tank in the right place.

i appreciate all the facts and figures but as someone said before; if up line and downline flight affect the leaning then surely it does matter? A central tank will minimise this affect, although depending on fuel level it will always happen to some degree. I guess the key is minimising it.

im going to look for one of these clunks that hold fuel as my current ones are Judy lumps of steel / brass with a hole in.

kennyglide

Hi, John thanks for the clear and concise advice .... i can lower my tank only as far as the tank centre line 5mm above the spray bar... i was thinking of mounting a DU-Bro E/Z fill fuel valves (the black plastic ones) just above tank height and i could just turn it off at the valve until i go to start the engine . The reason i wanted to install the valve in a high position is in the hope it will be more difficult for the fuel to move upward into the hose and siphon back down into the carb. I have seen a diagram somewhere where they looped the tank to carb line up higher than the tank in order to stop siphoning( not using a valve). I tried this idea on the bench but if there is fuel in the lower part of the hose it will suck the fuel through. If the fuel from the lower part of the hose is used up by the engine or deliberately drained ... or stopped getting there in the first place by the filler valve ,i am wondering if this would be a suitable setup.... if not using a fill valve maybe just a 3rd line filler and clamp on the carby line..... maybe i'm barking up the wrong tree here , i'd just like to know if these ideas would work and if these fuel valves or looping the hose up higher than the tank are worth while . Would it affect the tank and fuel pressure ? Ken

mike31

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I mount my tanks where ever they will fit. No problems!

Lightspeed1551

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Ask any one with a Grate Planes U-Can-Do with a non pumped glow engine. The siphoning action a will cause nothing but problems.

Jim Thomerson

Only time I have had a siphoning problem was on a profile airplane, Tower 40 side mounted with the muffler down. Metal tank with uniflow, and overflow vent, on top. Muffler line to the uniflow. I would fill through the uniflow line with the overflow vent open. If I capped the overflow first, then hooked up the muffler line, no problem. However, if I hooked up the muffler line to uniflow first, then capped the overflow, the fuel would siphon quite nicely into the muffler.

takEon

My first plane had a poor tank position. I had to takeoff very rich to not go too lean at the end of the tank. It was a hassle. I later learned about tank position. It is especially important when you spend a lot of time inverted or get into aerobatics. The end result of a good tank position is a very reliable powerplant for the entire flight. That dependability is paramount for me.

carl24bpool

I've just taken my Pilatus PC-9 out for two flights. The tank I enter is still around 20mm above the carb. It flew without problem and I flew loops, inverted, vertical climbs, consecutive loops, rolls a plenty, full laps inverted.

It didn't faulter at all.

The engine was probably a few clicks richer than usual but it flew without issue and I used 2 full tanks.

Im im not saying it's not critical, merely posting my findings.

I do have to be careful that fuel doesn't siphon into the carb but on a very low throttle setting it seems fine. It took a few spins on an electric starter to get it going but then it flew great.

JohnBuckner

My Feedback: (1)

You know Carl its actually kind of humorus, I don,t think I or the gentleman from Sweden ever used the word "Critical" in this thread. Nope. But the first use of that word was by the poster who had such a problem with us in his first post.

From my first post my entire effort was to help those who wanted to know how to deal with the ground syphon prpblem and I think I covered it pretty good. If your installation works to your satisfaction and you don,t mind dealing with the problem on the ground then great. I can tell you many folks who for a period ignore the problem (true there are many degrees of the problems severity) tend to grow weary of all the extra work and my goal was/is to help them if they care to listen.

What I don,t want to see is what occurred just this morning in the beginners forum where a gentleman from Australia gave up on an inverted OS 55AX and sold it when I think all he was dealing with was simple syphon and perhaps some flooding tendency.

John

Sport_Pilot

See post #3 the word was vital, which means essentially the same thing. I am with opjose although his math is all wrong. It is not critical for most of us, only for competitors. And, except for controll line facing the vent into the wind the wind pressure has nothing to do with this.

For most tanks with the pick up clunk at the bottom and vent at the top the correct placement is with the centerline below the spraybar. Usually about 1/4 to 3/8" but can be more or less. This is a statics problem. The tank pressure is reduced by the head of the fuel when the aircraft is upside down and the clunk will settle to the bottom so it has the same positive head rightside up or upside down. To prevent the mixture from leaning out when inverted the tank must be slightly low so that the head of fuel makes up for the lower tank pressure when inverted.

carrellh

"Vital" and "Critical" are the exact words used in posts 3 and 5.
Post 3
Post 5

HighPlains

My Feedback: (1)

Try it with tight inside and outside loops.

speedracerntrixie

My Feedback: (29)

Bob, how about an inverted spin? I've seen lots of dead sticks on that one. Like I have said before, it's all about the expectations each of us has on our equipment. There are some of us whom are just happy flying around and as long as the prop keeps spinning and we land the airplane without damage most of the time then life is good. Truth be known there are times that I wish I was that guy. Unfortunately I am the guy who will never be 100% happy with the airplane or the way I am flying it buy then again that's what has driven me to win two local racing championships in two years and a few years ago I was the points leader in the nation in the IMAC advanced class. For me and guys like me we search out every advantage we can that makes our airplanes perform better.

HighPlains

My Feedback: (1)

I know what you mean Shawn. I've seen post by guys they claim never to crash a plane, and that may be true. But that's not me, because I like flying down on the deck. Most maneuvers are pretty controlled, ie, loops, rolls, snaps. But spins have a bit a variation where it sometimes takes an extra 1/4 or 1/2 turn to recover. You might do 3 or 4 hundred identical spins, but then get that one that goes that extra partial rotation is tough when you don't have the altitude. I suspect that thermal activity causes the variation, but have no proof.

My biggest problem is with tail slides. I've let them go all the way down to a pancake landing, but when you get one perfectly lined up it is tough to bail out early.

DaleJEckart

My Feedback: (5)

I have a TF Corsair that I will be building, but I will have no such problems - an inverted DLE 20 will run just fine in it, regardless of tank position