DeviousDave

The Norvels weren't particularly good heli motors, and make a LOT less power than I think this Picco will.

AndyW

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Hi Dave,

Well, in my opinion, the Norvels were good motors all around. The problem was that Norvel wouldn't listen to Dave when he reported that they were all set up far too tight. As such, they seized up and bent rods regularly. The last batch from Norvel, the ones selling close out for 25 dollars, have been set up a lot like late Cox engines. Easily runnable from the getgo with no break-in required. I preferred a BIT of a pinch but better light than too tight, I guess.

You may be right about power but my LM versions of the .06 did 19k on 25% on a Tornado 6 X 3. Greg, once your done, can you give us some figures?

But the point I hoped to make was that the LM Norvels pulled their far heavier machine quite decently. The much smaller and far lighter T-Rex types would likely do well in that regard. In fact, this was one of the projects I had started back in 2007 before the roof caved in on me. I had already adapted an exhaust throttled, LM Norvel to rear exhaust and that can be seen here. http://www.youtube.com/watch?v=RiLit...eature=related and here, http://www.youtube.com/watch?v=qHD3D...e=channel_page is an early version where I tried to use carb throttling along with a custom, rear exhaust muffler. Using an exhaust throttle ala LiteMachines worked better and is simpler to hook up.

But still, as you suggest, the .06 might not do the job. In that case, I've got several LM .074 Norvels to try.

A big issue is adapting the LM clutch to the main gear of the T-Rex and much searching found me the right pinion,,,, metric and quite special.

The rest of it will be stock.

Mr Cox

I don't know much about the helicopters but in airplanes the Norvels are the standard to which other engines are compared...
I think airplanes are quite demanding on the engines actually, compared to cars that mainly need high revs if there is no gear shifting available.

In helicopters it seems to me like one would prefer a high torque rather than just a high power at high revs. In other words a diesel would do well, while a car engine would require a gear box? Also, I can't imagine hovering a few meters away and having an engine at full bore (30-35k ?) being very pleasant or relaxing... [X(]

But please show us all wrong and beat the Norvel on a 6x3 prop!

gkamysz

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Torque does not fly anything. Torque at RPM commonly known as horse power does work. In a heli, which has gearing anyway, it doesn't really matter what the RPM or torque output of the engine is as long as the right amount of HP is available. You generally run the engine at an RPM near the peak HP and it's always at that RPM regardless of load. Because the engine runs at one speed, it's easy to design a muffler that is very effective. Heli engines, in general, are not loud.

Ok, to the shop to produce some swarf. Photos to follow.

MJD

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Someone who gets it... someone who actually knows the difference between HP and torque.. what a blessed relief.

MJD

combatpigg

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For most of the 1/2A performance designs that get flown here, the 5x3 is a good benchmark prop to compare engine performance with. The AME .061 turns it about 26,000 which sets the bar at a pretty good height. I think my old Fora could only turn it about 24-25,000.
An engine in the Picco's price range would be expected to turn a 4.2x4 in the mid 30's.....but this prop isn't practical for most models. If it can pull a speed prop in the mid 30's or better, then that will be quite a find for the speed guys.

AndyW

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Therein lies the difficulty, in part, in understanding torque, RPM, prop diameter and pitch, drag, wingloading etc. etc. as to how all of this relates to how well any particular model flys. Load a diesel with a bigger than glow prop and it will run slower, just as if it were a glow engine. BUT, that prop will still keep chugging along in the verticals far better than the glow version on the same prop. The glow will sag due to delivering less torque. SAME power from the same engine. BUT, larger props tend to be more efficient at certain airspeeds so that adds to the confusion. Put a small prop on glow at 30K on a heavy, draggy airplane and the prop will cavitate and you'll pretty much go nowhere. Same plane, same engine but make it a diesel along with a bigger prop and now you have a whole new plane.

From Encyclopedia Brittanica.

+++++++++++++++++++++++++++++++

Torque also called MOMENT OF A FORCE, in physics, the tendency of a force to rotate the body to which it is applied.

The torque, specified with regard to the axis of rotation, is equal to the magnitude of the component of the force vector lying in the plane perpendicular to the axis, multiplied by the shortest distance between the axis and the direction of the force component. Regardless of its orientation in space, the force vector F can always be located in a plane parallel to the axis.

In the figure, the force vector F lies in the plane parallel to the line OL; the component FL, being parallel to OL, has no moment about OL, while the component FP, lying in the plane perpendicular to OL, has a moment, or torque, about OL equal to FP * d, in which d, the shortest distance between FP and OL, is the moment arm or lever arm.

+++++++++++++++++++++++++++++++

Posted is the figure. Geez.

Kind of reminds me of a piece on "The Learning Channel" Where they were trying to explain to the average viewer, how a plane flys. The usual Bernouli explanation was given along with loads of tech jargon.

Quite simply, for the layman, they could have just said that the wing "scoops" the air and this provides lift. Sure it's simplistic but for the average viewer, it's perfectly adequate. And if it's not to any particular viewer, that could stimulate them into finding out more,,, instead of turning them off.

But this was about a Picco car engine being adapted to fly an airplane. I'd guess that the engine could be run with a variety of props on a standard fuel (25%) and that would give a fair comparison to other engines. Naturally, I'd convert it to diesel, just to see.

If anyone picks one up for cheap, I have a NIB Norvel .074 for trade. This would include a turbo insert.

Mr Cox

You wont fly anything without torque either...
I'm sorry if I was a bit unclear there, I had no intention of starting a debate on that issue actually. But given two engines that produce the same power I would prefer to have one with a higher torque since it would run at lower revs when producing that power.

Sorry for sounding a bit sceptical, it is just that car engines tend to pop up everynow and then. People seem to think they somehow managed to do something special in these when in fact the same rules apply to them as those that have already been used in airplane racing for a number of years...?

Not so long ago there was a lot off fuss around the Fuji engine (shown below). It was originally designed for cars and seems to work well there (as I have understood it) and it is was then adapted for airplanes. It turned out rather heavy and low on power. I'm still waiting for people to show off their creations or even to show any plane that has actually been in the air with that engine in the front... [sm=72_72.gif]

gkamysz

My Feedback: (19)

Making a high torque engine is much harder than making one that has a decent amount of torque over a higher RPM range. My comment was specifically about the application in a heli. If you are turning a prop on the crank this is a different story. If you have gearing available, displacement limited, and peak performance is the goal high RPM always wins.

You don't have to explain to me how torque, RPM, HP, work together to provide the resulting performance.

The Picco is just interesting at this point. I'll figure out how how well it works soon. I'm skeptical of this engine right now too. There is only one way to find out what will really happen.

DeviousDave

I'm not saying that he Norvels didn't make enough power for flying a heli, just that for a proper heli-one that will compete with modern electric 3D types, it will have to have a better power to weight ratio RTF than the LMH series did. I did a BUNCH of testing on the early Lite Machines helis.. The first attempts were with a VA .049 with a throttle at a time when they were using the TD. That was a great powerplant! Then, I switched to an Astro 020. Hover power (including the wires attached to the whatt-meter) was 69w. Just about any 1/2A will deliver that and more, with the exception of the reed valves.

As for gearing, I'm betting that Small Parts Inc. will have what we need. I'm planning on using the clutch design from the LMH to keep from shredding gears-it's pretty heavy. Luckily, I won't have to make another clutch shaft as with the VA with it's prop stud crankshaft.

DeviousDave

A lot of the reason that people have troubles with getting power out of a racing or car motor is that they don't prop it correctly. Even standard 1/2A props don't work well on modern 1/2A's. I remember getting my first instruction sheet for the VA .049 in 1993 or so and it saying to just forget what you know about props as the ones commonly in use were meant for a 50 year old engine. Those thoughts stuck with me over the years. The Torque Curve of a Cox motor works very well with a 6-3. Put that same prop on an AME and it's just too much. Doesn't mean that the motor is a POS, or not worth experimenting-it just means that you aren't using it properly for it's intended use. Same thing with racing or high performance .15's-my Dad has a Conquest he runs an 8-4 on and bagged on it because it's not fast..... The engine needs a 6-6!

If this Picco is timed as wildly as I suspect it is, a 4-4 prop may be too much. You never know until you try.

RocketRob

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To quote Carrol Smith... "Torque wins motor races while Horsepower sells motor cars"

RocketRob

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Tag Andy - you're next

AndyW

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Well, that reminds me of the Enya 11CX. This was a full ball bearinged, true AAC engine, adapted from their top car engine at the time. As I recall, it was a real brute for its day, IN CARS. As an airplane engine though, it disappointed. Yes, I stuck on the same prop that I used on what it replaced, an OS Max .10. The Enya flew my small Pitts better but not so much better as I had expected given the HP quoted for the engine. Prop selection was my undoing but I did have that big Pitts cowl to clear. I eventually turned it into a diesel but never did get to try it that way on the Pitts. Not after I discovered that a stock Norvel .15 was no heavier. Car engines don't need to be light.

I'll be getting a Picco eventually and will convert it to take a prop. I have the perfect test bed for it but that'll have to wait a few months. We're enjoying the coldest winter in decades. Global warming is a fickle mistress. I thought we'd be dodging coconuts by now.

My definition: torque is a twisting force measured in ounces or pounds at a given distance from the axis of rotation. When we buy a servo, we always want to know the torque. BUT, we also want to know the speed as well, giving us a better picture of what we're getting. Anyone can make a super fast servo (good) but it might sacrifice torque to get that speed (bad). It all depends on the gear ratio. A strong AND fast servo depends on the motor and amplifier. A strong AND fast engine depends on ????

For years we saw HP figures come from the engine makers. Then we found out that these figures were derived not quite at the RPMs we'd typically fly the engines at. Lots of confusion stemmed from that. But that only means that the marketing guys won over against the engineers who knew better.

My impression about cars is that they have the need to accelerate very quickly, out of the turns. This means high speed and low torque on the engine which will be geared down to provide the torque needed to do the job at the wheels. Aircraft have far different needs. Anyone remember gear boxes and belt drives for airplanes? That didn't last long, did it?

We may just find out that car engines are car engines period. OR maybe there's a simple fix to make them great airplane engines. Fun trying.

gkamysz

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I got sidetracked on mine. I made a new head, but not the rest of the parts. Looking through my youtube subscriptions I found Andy's new video.

http://www.youtube.com/watch?v=8vxwmZI2HlU

DeviousDave

What size prop Greg?

MJD

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I bought one at the time people were raving about them. I put on a 7-3 Graupner as I recall and it didn't blow me away off the bat, but I do need to get it out and back on the stand. But talk about a bunch of metal hanging out in the breeze - that carb has enough real estate to turn it into a .40 size. How fast does it need to turn to be happy and productive?

MJD

digital_trucker

The notes on the video said it was an APC 6x2 trimmed down to a 5x2.

combatpigg

My Feedback: (3)

MJD, the Enya .11 will do pretty good work with a 6x4 on a clean plane. IIRC it will turn this prop about 21-22,000. Without at least a 4 pitched prop, this engine is just another noise maker.

I've never run a 1/2A Picco, especially not to drive a prop.....but I suspect it needs lots of nitro to get a higher fuel flow rate through large intake passageways and to replace torque lost due to early exhaust timing.
60-65% nitro is not unheard of.

MJD

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I'll toss an APC 6-4 on it on the test stand and see what it thinks. If it doesn't run fast enough I'll unload it until it does then give it a few minutes on the bench until it behaves. What sort of nitro content is it set up for stock, do you happen to know? I'd be tempted to use anything a VA or the like would enjoy, as in 30% nitro and 22-23% oil, sort of a standard small engine gonzo sport choice to me. I'll have to dig to see if I kept the box and bits in case there were shims or whatnot there. Bin a while. This isn't one of those "run only all-castor" engines is it..? I think it should be happy on a syn/cas blend.

MJD

RocketRob

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Well here's mine,

Ah hmm 4.2x4 and 37,400 rpm out of the box with out a proper break in

146mph pitch speed

I think I like it!

RocketRob

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Oh and I have one at Macs Products for header fabrication. Can't wait to put a CS pipe on one.

And a noise maker it is - sortof a satanic howl

skaliwag

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Rob.. Are you trying to match the Shuriken's #'s

RocketRob

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I think this is in Cyclon and Profi territory without a fricken hassle bladder on suction with a carb to boot.

still a bit heavy however.....

Don't know anything about shurikens except the last two on the bay went for $250 and $350 I think - I paid $28 formy motor, $34 for a complete OS .10 (for the carb), $8 for OS turbo plug, and I think around $15 for Toki prop driver and nut, and 15minutes on the lathe spinning down the head.
I'm happy

combatpigg

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ROB, That's incredible! I'm pretty surprised.
Sign me up!