XJet

When I first put my Norvel 061 in a plane (my littler-stick) I tried a 6x3 Tornado prop (as per the instructions I think) and it was quite disappointing.

After switching to a Cox 6x3 (black) I was much happier and have put a liter (pint and a half) of fuel through the engine like that.

Yesterday however, I thought I'd try a 5x4.

I didn't expect too much because my Littler stik was not exactly over-endowed with vertical performance and I thought that a coarser pitch with smaller diameter would only worsen that situation.

Well I'll be blowed -- the Stik now flies about 15 mph faster (or seems that way -- I estimate its straight-and-level speed to be around 45-50mph) and the vertical performance is about 30% better.

Now I'm well into my second liter of fuel :-)

I'm now running 20% castor oil instead of the 10% castor/10% CoolPower I ran in the last batch and notice that the engine loads up a lot more when it's been idling for a while -- like when opening the throttle up while doing touch-and-gos. Anyone else noticed this?

I don't care much though -- this stik is now even more fun to fly with the extra grunt I've got from the new prop.

My admiration of the little Norvel continues to grow.

Lynn S

I flew my .049 Norvel for the first time today. The plane seemed to go faster with a 6x3 Master Airscrew prop over the 5x3 cox "rubber ducky" It really turned up with the 5x3 but the rpms fell after two or three minutes. Maybe it went through the fuel faster due to turning so many more rpms. I'm not sure if the plane was going any faster with the smaller prop.
It is a sweet little engine, very steady, and more than happy to run in any position I could put it.
I have a .061 AME too but I'm not ready for that one yet.

gcb

Some folks seem to like the APC 5.7x2 on the BigMig .061. Norvel engines like to rev.

George

Edit: Oops, I don't think APC makes a 5.7x2, make that 5.7x3 or 6x2...sorry. []

Japanman

My (limited) experience with little props is that the stated pitch seems very inacurate. I do wonder if the majority of older props moulds were made by hand and more or less by eye- they sure seem that way. The newer props made with cnc by comparison seem much more consistant in the pitch.

J.M

Oh yeah, I have found the same sort of thing running castor- I think less of it vapourises in the chamber and tends to be more globby and thereby tend to putout the glowplug at lower rpms.. But I don`t care either- I think upping the nitro by 5% may improve it - you are running about 15% nitro?

SST

My Feedback: (2)

Try a Cox gray prop and hold on...They're all I use on the small engines.

MikeSell

My Feedback: (2)

Finding what works for you is the name of the game. Too few people actually compare props and performance. Most just stick on a recommended prop size and brand because "thats what I had" or "I asked at the hobby shop and this is what they gave me." I found major differences in thrust and needleing with different brands of props.
I do not agree that Norvels like 20K rpm better than 16K. Much of that has to do with the prop and the plane it is used on. Flyability is the name of that game.
I have club members making appointments with me to tune their Norvels to run as well mine. One of the first things I do is change their props.

BMatthews

Quite right Mike. I've also found that what works with a given engine on one model may not be right for the next.

I wonder what a 5x3 Cox grey would do for you Xjet? More revs than the 5x4 but less pitch may make for less overall speed but I'll bet the climb would be a honker! And then there's the APC 6x2. This one save my bacon on an overweight Nostalgia class free flight model I did.

Tom @ Buzzard Bluff

[quote]ORIGINAL: MikeSell

<I do not agree that Norvels like 20K rpm better than 16K.>

I've been waiting to hear that for a looong time. Seems all I see is "Put a 2.1x.03 prop on , feed it 90% nitro and jump back"! Dannit! I don't want to hear an engine shriek like its gonads are in a vise. Noise does not work make IMO. So tell us how you manage to make the Norvels get down and grunt. I'm waiting with bated breath. I'll bait it with bourbon if it will help. Tom

Settle down there Stobaugh!

cali_dream

I couldn't agree more. Seeing the NORVEL engine designer at the flying field sheds some light on this. He tries an APC 5.7x3, then a Cox 6x3, then something else. He adds a copper shim under the plug, removes one, etc. The most knowledgeable engine man I know plays around with these combinations just like the rest of us!

When you ask him about it, he will say similar things, it's not worth studying it all scientifically with a model it's easier to experiment. He once told me that 20% of his engine designing process is done by formulas and the rest is just tweaking things, too. Make the venturi a little smaller, a little bigger, etc.

Often in representing NORVEL I feel a bit strange saying the best way to tune up your motor is by experimentation, the newer guys always find this interesting. "Really?" "Yeah, just try a few things and see what works!"

Have a great flying weekend! -Ed

BMatthews

The old control line speed flyers know all about this method. For sport flying so many just assume that the tried and true formula is fine and never venture outside of the box.

A few years back I made a hot rubber Coupe d'Hiver model. It had replacable blades. I made and played with 4 sets before I found one that worked as I wanted. I probably could have made another 4 and found a further 10% in performance.