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Old Nov 12, 2012, 07:55 AM
Radiodel-hooooo
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Maybe look into motocross gas boosters already made and optimized for the job.
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Old Nov 12, 2012, 09:25 AM
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Originally Posted by jockstrap View Post
Bert - you're convinicing me

I've just scouted around for oil prices and good glow synthetic seems to be around $66 per gal here if you shop around vs about $40 for caster.

Do you think caster alone (say 20%) is sufficient with methanol ? can i go lower - say 15% on caster or maybe not?

does the large amount of oil foul the spark plug at all ?

I think a 50% savings on going to 0% nitro and a spark - whilst maintaining virtually the same power may be a good thing - as for approx $60 for a cdi unit - that money will VERY quickly be covered and way more saved as flying time goes on during the year..

Also Bert - have you had any experience running gas and glow fuel mixed togather?

I read somewhere I could mix 2L of gas with 1L of glow fuel (20% nitro 20% oil) and end up with a good mix to run on a spark ? That would end up at a good price as well.. (possibly need some acetone to assist the oil mixing with gas)... any comments on that?
I have no experience with sparks and castor, but as far as I know, in the US virtually everybody is using castor, and I have not heard any stories about "spark and castor don't mix".... but I would not be surprised if full castor only might give problems. But that is only a hunch, I have not touched castor in years myself.
As far as I know, keeping one plug soaking in Acetone in you fieldbox solves that problem, and contrary to glow, you can thus "recycle" the sparkplugs....

For glow, there is no doubt, 20% Castor will do.
In my experience, I would say 0% Nitro, and 18% of a GOOD glow lubricant (Klotz, Carbulin, Aerosynth or Aerosave) should be sufficient, based on leaning out to the max.

I base that on my experiment with the fourstroke, where after the spark conversion and leaning out to the max, I needed to increase oil content by 1/5 (from 10% to 12%) Which is in line with the theoretical reduction in fuel consumption by 20%. (and yes, I did not just guess that, I started after the conversion with 15% oil, went gradually to 10% in steps of 1% and found 12% to be the best).
Combine that with the fact that with glow ignition, in a 2-stroke, 15% Carbulin on 0% Nitro functions OK, Than it follows that with spark ignition and 20% reduced fuel consumption, an oil content of 18% will give the same amount of oil through the engine.
I would personally not go any lower than that.

Yes, the CDI unit earns itself back: on my fourstroke, I have more or less run 10 litres through since conversion, and I need another 20 litres and it will have paid for itself. For that heli that will be one season, max. Power on 0% Nitro, 12% oil is equal to even slightly better compared to glow and 10% Nitro, 10% oil, but consumption is noticeably lower. And on glow, the engine would not survive even 5 litres of the 0% Nitro mix....

I have no experience with mixing of glow and gas, and I am not intending to get that either.... Too much possibilities for lubrication to go wrong. I am sticking to Methanol, but will convert gradually all helicopters to sparkers, because I am seriously convinced of the running and handling, and the ease of adjustment.

No more problems glowing or starting, no more worn or burnt out glow plugs No more engines that stall while carrying the heli to the pad, just charge your ignition battery and GO!

Maybe I will one day try a ringed engine on gas, but at the moment I have too many experiments going on....


Brgds, Bert
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Old Nov 19, 2012, 02:51 PM
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Proudly presenting:

The Liquid Cooled RC Helicopter!

Vario Xtreme liquid cooled engine.wmv (7 min 19 sec)


Brgds, Bert
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Old Nov 19, 2012, 03:52 PM
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As if multi blade heads aren't trouble enough...

Nice video. It suddenly occurs to me that the cooling flow keeps going even after the motor stops.
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Old Nov 19, 2012, 04:22 PM
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The problems with multiblades are a general misconception:

You have to learn to fly a multiblade (or an unstabilized rigid in general, a 2-blade without flybar flies exactly the same) but once you get the specifics, it is really not that hard. The strange thing is that people are perfectly willing to spend 6 months learning to fly, taking the risks of crashing etc etc, but seem to be completely and utterly NOT prepared to spend the approximately 5 hours (say, 15 to 20 tankfulls) of flight time to adjust to a rigid.... With the excuse that they don't want to crash it, while in fact the chance you crash your multi during the learning period is fairly small to almost non-existent, as long as you are careful.

I fly two 450 size multies, a 2 blade rigid .60 sizer and a 4 bladd 6 ft Gasser as well and all are without E-stab.

And yes.... the cooling circulation starts a bit slowly (it takes aprrox 30 sec idle before the first faint circulation is noticeable) but it continues until the engine is completely cooled down after stopping.

Brgds, Bert
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Old Nov 19, 2012, 08:23 PM
Radiodel-hooooo
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It works ! Well done but now the real test is in summer or even USA desert or sem-desert conditions. I hope it does prove worth your efforts.
Just a tease here but do you have a patent on the canopy stretcher seen at about 1:00 ? Pretty cool.
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Old Nov 20, 2012, 01:48 AM
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It works ! Well done but now the real test is in summer or even USA desert or sem-desert conditions. I hope it does prove worth your efforts.
Just a tease here but do you have a patent on the canopy stretcher seen at about 1:00 ? Pretty cool.
Maybe it's me, but what do you mean by Canopy Stretcher?

Been thinking a lot about possible improvements to the system lately, Not because I encountered cooling problems, but just to keep the mind busy, and because I am fully aware all parts and bits are crude, handmade (or should I say hand-butchered ) and therefore not optimal.

There is a lot to be improved, but the bottom line is, it definitely works, and as with all common systems, there is always room for improvement

Currently I am working on a membrane pump incorporated in the backplate of the motor, not because I am encountering problems, but to make the system independent of the positive G forces. But I am somewhat hindered by my machining equipment and my supply of roundstock.

What I have found so far, is that as is now, convection flow does a good job up to just below take off, and also in FF, there is no vapour forming due to the higher airflow around the radiator. When heat load increases or speed decreases, vapour forming occurs, and that is a real boost to the flow, and limits the temperature very effectively: no matter how much steam I see in the upgoing hose, the engine keeps running consistent. It is not really visible, but during that video, there is a fair amount of steam forming happening during hoover, but I have not lost a drop of water. I really like the fact that the system is more or less self controlling, but don't like that I am depending on positive G, hence the pump.

Logically, I have not yet any experience with hot climates, but the temperature difference of 10 degrees C that I have encountered so far did not seem to make any difference at all.... Probably I will have modified with a new radiator design long before summer arrives.

Brgds, Bert
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Old Nov 20, 2012, 02:27 AM
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Originally Posted by Brutus1967 View Post
Maybe it's me, but what do you mean by Canopy Stretcher?
At the 1 minute mark, the video distorts and everything stretches vertically... nice effect. I didn't spot it before because I was watching a Harry Potter film on the tv, eating dinner, buying something on Amazon and watching your video on my phone all at the same time...

Anyway, the proof is there. You definitely made the most money with your high flow water jacket.

And I figured as much with the multi blade/rigid head setups... but some of us fear the unknown and would rather gaze in amazement. It's easier to assume you are amazingly talented.

Cheers,
Vince L.
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Old Nov 20, 2012, 03:41 AM
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At the 1 minute mark, the video distorts and everything stretches vertically... nice effect.
Ah.... here I just see the motion flicker a bit, but no stretching, or at least I didn't notice it


Quote:
Originally Posted by Vince77 View Post
but some of us fear the unknown and would rather gaze in amazement. It's easier to assume you are amazingly talented.
Hehehe, if I were really that talented, I would have made a little bit more out of it than just these basic lazy eights....

But, OK, lets keep it at "I am amazingly talented and you all are NOT... "

Just kidding.... it is really not that hard, just getting used to something different.

I have never understood why people would accept the fact that you need to learn how to fly anyway, and let's face it, all of us have had a point where we thought all those video's are just all fake and it is simply impossible to control a helicopter, but when somebody (probably somebody you don't even know personally, you typically read about it in mags or forums such as this) tries a multiblade for maybe one or two tankfulls, gets scared and declares them "nearly unflyable", then suddenly and strangely enough everybody takes over that opinion....

I have been scared of them too for a long time, but when I was "forced" to fly one (my buddy built one and asked me to maiden it) for me it was immediately clear they are flyable. Different, and because of that, "difficult" at first, but absolutely just as flyable as any flybarred heli is to a newbie....

So I can understand, people believing others in saying it is difficult, but I cannot understand people trying for 5 minutes and giving an unjustified verdict in the first place....

In fact, and this is true: I have as an experiment, used that same helicopter in the video, as a trainer to see how an absolute newbie would fare with it, and to be honest, I could not see a difference in progress compared to the other guys training on a flybarred rotor. In fact, when that guy changed over to flybarred, he had some serious problems readjusting to the "easier" system....

So far, a number of people in my flying crowd have made the change, and none of them has crashed due to the "difficult characteristics" of the rigid rotorsystem.

Brgds, Bert

EDIT: but apologies for the off topic rant.... are there any new developments on the gasser-conversion front?
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Old Nov 20, 2012, 05:56 AM
Radiodel-hooooo
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By the photos it looks like a normal mechanical system, nothing looks stupid. Ultralight and snowmobile motors have a nice fuel pump design that works reliably, but we either changed the diaphragm each spring, good or not. A good bit large and heavy for your heli.
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Old Nov 20, 2012, 06:06 AM
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The problem is not in designing a pump, and also not in weight (I can design a pump weighing less than 25 grammes, no problemo). The problem is in making it with the means availlable to me.
But that will be a nice project when I'm back at sea....

Brgds, Bert
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Old Nov 30, 2012, 09:09 AM
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Progress on a cooling water pump

And since I am back at sea, here's an overview of the progress so far.

Unfortunately, I forgot to bring my AL75 aluminium "weld" stuff, so I can not complete the project while on board....

Anyway, as can be seen in the pics, I made a new backplate for the Rossi (didn't want to drill holes in the original one), two pump plates containing the in and outlet porting and some cavities for the flapvalves to move around, and a rubber valve "gasket" made out of an old inner tube.
A supple membrane made from a chemical resistant glove should withstand Methanol and oil, but maybe I need to find better material for that.

The pump has a designed stroke volume of roughly 1 cc (.06 ci) but that is of course not going to happen at full 15000 RPM.
But if I am getting a volumetric efficiency of 5~10% I should be allready getting a flow of 12-25 grammes per second, and that should do it. (of course I am hoping for more... )

Parts missing are the in and outlet connections....

Brgds, Bert
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Old Mar 03, 2013, 02:02 PM
Radiodel-hooooo
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How are the conversions going ? Spring is on the way and I could use a noisy helicopter.
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Old Mar 03, 2013, 04:34 PM
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I guess there is less and less need for conversions.
OS has a .90 (15 cc) gasser helicopter engine out and I think everybody is waiting for even smaller versions.

Brgds, Bert
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Old Mar 03, 2013, 04:37 PM
Radiodel-hooooo
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Probably $3000.

I hope it's reasonable, I read about an hour's flight on a 20 oz tank. Actual is about $450, I'll have to wait on a DLE or RCGF.
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