David.....I made some experiments some time ago and determined that glow fuel weighs about 1oz per liquid oz.
If you are allowing 1 lb for fuel....you'll have about 16oz of liquid weight.
You could likely plan for 12oz standard fuel and save a 1/4 lb or more while you are at it.
The reduced nitro (10%) used with the NR will remove half the nitro weight. The oil content will have an effect on the weight too.
You can weigh 1oz of the fuel you intend to use in a 1oz mixing cup and get a grip on it.

Before the 89' NATS in Washington State....I was using the YS RE ss and was running out of fuel on the next to last manouver.
I could not get a larger tank in the airplane (Suprafly) so I mixed my own fuel....13% total oil (8 castor/5 KLOTZ) 20% nitro 2% propolyne oxide.
This mix actually gave quite a bit more RPM than standard 18/20 fuel due to the much reduced oil drag.
The castor kept the engine happy without gumming up the works...and at the NATS I was landing with about 2 oz reserve.
I had to do this to gain more endurance...it's all about considerably reducing the viscosity of the fuel to allow the needle to be closed....less fuel through the engine....
How can you gain RPM with less fuel flow???
Reduced oil drag.
Works great.

Dave

Tim....the last time I used anything like a bladder tank was a baby nipple for control line racing. So what I'm trying to say is I need to learn about Bladder Tanks.
It does sound promising.

The wind was up again today so I got another run on the Rossi. I have it leaned enough to fly with good transition from idle. I can feel the engine coming on.

UPDATE..... I just finished running up the NR Speed 13 after a little over 1/2 gallon of fuel. On this run I tweaked the top end and made an adjustment to the bottom end and the results....

WOW she is screaming!! The transition from idle to full throttle is the best I've ever owned. I'm still running it a little rich on the top end but awesome power coming out of this engine. Everyone was right, it takes a little while to break it in then your in good shape.

Thanks for all the help guys.

Keith

Dave,

that is an interesting thought. I never really put much stock into the density of fuel. What with the conversion of fluid ounces to mass ounces being among the most straight forward in the world of imperial units!

But in short, yes, when I said a pound of fuel weight, I had a 16 oz tank exactly in mind. 16 oz of fuel = 16 oz of weight :-) Given my testing thus far, I'd say that a 16 oz fuel tank is the most prudent with this engine in a practice situation. Naturally, in competition, a 12 oz tank might just get through the routine and be preferable.

Say, is the density of nitromethane substantially higher than that of methanol? I'll have to look into that.

Interesting story. How much fuel were you carrying on the Suprafly? What purpose does the 2% propolyne oxide serve?

Coincidentally, I have just been experiencing improved performance on the Speed 13 as a result of reduced oil drag. I've been running different fuels through it with different total oil content and blends. Going from 20% oil to 17% alone (although the mixture changed) improved engine performance. Not significantly but measurably.

David

Hi Dave Harmon, I've tried sending two PM but still do not see them in my sent box. Can you try contacting me? I live in Broken Arrow. Thanks Ralph

Wow!

I just checked. The molar mass of methanol is 32 g/mol for a density of ~792 kg/m^3. Nitromethane has a molar mass of 61 g/mol and a density of 1140 kg/m^3! Nitro also freezes at -29C while methanol freezes at -98C... I guess the latter is the reason why we can stick our vodka in the freezer (ethanol freezes at -114C). Oops, I meant fly in winter.

With nitro having a density close to 1.4 times that of methanol, it becomes clear that high nitro fuel weighs more. For simplicity and to get a handle on it, If we assume that a fluid ounce of 10% nitro weighs 1 ounce, increasing the nitro content to say the typical 30% "heli" fuel would result in a tared gallon of fuel going from 128 ounces to 133+ ounces. That's not insignificant.

Given your testing Dave, the oil has an even bigger impact. I'll have to look into the loss of weight in going from 20% oil content down to 13%.

David

Keith,

glad to hear all is coming along nicely. Portales is up at 4000 ft so your loss of oxygen will affect performance slightly. I used to live at 7,400 ft in my youth modeling days and engine performance took a significant hit. it was always fun to drive down to the beach (an 8 hour drive at the time) as you could feel your car pull more and more on the highway. This was down in Mexico so we could open up the throttle back in those days. (One still can but it is a little more costly these days...)

I assume you're running the stock NR header and pipe? Have you made any changes to header yet? What fuel are you running?

David

Will, thanks for the suggestion - I'll have to look into the Hyde mount.

UStick in Germany has done some interesting simulator testing with the Brushfire which he modeled into Aerofly (if memory serves). He has an interesting writeup on his experiences both altering the models weight as well as changing its power source (piped glow and electric). I can see the model still flying well at 9+ lbs (which he agrees with) but I'd like to achieve an 8.5 lbs wet model weight if I can.

I'll need to source some gear that will go into this model to reverse engineer things a bit and see what can be done. At present the model is guided by 10 servos (6 fuse, 4 wing) with the limitation that I don't have a 10 channel Tx! Ideally, the servos would all be operated on individual channels.

An Arrow 120 sounds most cool too. It sounds like it will require some glass deck work. How long an exhaust and pipe does the Jett call for? Does it turn 13-14" props?

David

I am running the stock header and pipe. I haven't made any changes to it. You are right about the altitude here. When I would go to sea level to fly in a pattern contest I always tried to get there a day or two early just to set up my engines. It was like having a super charger on them.

I'm running Wildcat 10% with 3 oz of castor oil added to it. I'm probably going to mix a few fuels together to get about 12 1/2 percent nitro. NovaRossi is pretty stun on running 10% fuel.

We should be able to improve performance yet by tuning the exhaust for smaller props. If you plan to turn an 11x7, 11x8, more RPM should be available. With the larger "long stroke" props (12x8, 12x9), the exhaust is actually a little restrictive and a longer pipe may be needed.

I'm reading that Wildcat Premium has 16% oil with a 20/80 castor/synthetic mix. That's pretty low castor content for the beast. No doubt it will perform well but it might be somewhat life limiting in the long run. It's likely a good thing that you added the 3 oz of castor. 5 oz might be even better.

Personally I'd really like to source 50/50 20% oil fuel (e.g., Sig Champion or Morgan 4-stroke) and dilute it with methanol. Find out where the sweet spot is ;-)

David

Hi Ralph...PM sent.

From what they are telling me the pipe should be pretty close. It would be the first one out of 50 or so I've set up...but it is close where it is. The Wildcat fuel was all that I could get and had to go 200 miles to get it. I used to run Wildcat back in the Ducted fan days and it ran very well. Having said that I haven't run a nitro engine in 5 or 6 years so I'm just making guesses. The engine is spitting a lot of oil out of the exhaust so I'm comfortable that the oil is good for now, I now have some Power Master 15% I need to look into.

If I was a betting man, and I am, I'm thinkin the Nova Rossi will be the most powerful engine on the market....time to get it in the air.

Yes....as you discovered...nitro is much heavier than methanol.
On the YS 170dz 4 strokes most everyone uses CP 30% Heli fuel. It also has 22% synth oil....a gallon weighs a ton.
The low oil CDI version of this engine uses as low as 5% total oil....I tried it but the n/v was very sensitive....because the viscosity was so thin that the n/v was almost closed.....so a small adjustment made a large change in fuel flow through the now very small hole in the spraybar. If they would put a finer thread on the n/v it would probably have helped....or changed the taper of the n/v point.
I went back to 15/30 all synth and it runs great.

If I remember correctly....the Suprafly had a 10oz tank...definately short tanked.
With the YS pressure I guess I could have added a header tank but I didn't think of that back then.

The propolyne oxide was a habit I got into mainly for improved idle and as a guard against a flame out on an important flight.
You can also impress your friends by hand starting the YS/Rossi/NR without a battery connected to the glow plug.
That always left em' saying....'How he do dat??'

Prop oxide might be a EPA victim by now....I haven't used it in some time....mainly due to it's availibility. The race fuel shops in LA had it for about $8 a pint.
Today...some guys use 1oz of acetone added to a gallon of fuel.
It works almost as well as prop oxide.

Anything you do to reduce the viscosity of the fuel will give increased fuel mileage and rpm.
You can remove castor and add back the same amount of synth oil and get a performance increase....less viscosity.
Or...use all synth but a thinner viscosity oil.
Or....because castor is such a good lube but thick....you can use a lot less total oil but increase the % of castor while still using some synth...and get still better mileage.
The lower the total content....the more % of the total should be castor.

On a true ABC engine like the Rossi/NR I would not go below 15% total oil due to the critical piston/cylinder fit....some of that needs to be castor.
The YS 60ss had a AAN or ABN piston/sleeve and while ok it really was not anywhere as good as true ABC which is the real quality of the NR and other engines mainly from Italy.
AFAIK....all Japanese engines of this type have never had true ABC. The OS non-ringed engines since about 82' that peel nickle off the cylinder walls are especially pitiful.
I must say though....the YS 60 RE ss running 13% total oil performed in an unbelieveably spectacular way......but I was not concerned about the piston/cylinder fit.
Later on I replaced the piston/sleeve on that engine with a Shadel mfgd pair and got the NR quality ABC. It ran great on 17/20 all synth.

Dave

Yes, on small props I think so too. But I'm willing to sacrifice a header in the interest of verifying the tuning. If it's too short after cutting, I can always go back to stock,

:-D

The actual computed horse power is staggering. We still need to put the YS Classic through its paces (at least I do) so time will tell...

David

Guys.....If you are thinking of adding more oil....don't add castor.....add synth.
Modern engines really do not need castor for good running.
A VECO/K&B 61....yes....22% straight castor, 15% nitro and they run great......with a lot of slobber.
Go to a motorcycle shop and get a quart of KLOTZ KL-200 all synth and bring the total oil to 19>20%
I wouldn't go any higher than 20% oil.....don't need it anyway.

In any event...I think all the engine mfgrs like to spec castor oil because ot corrosion considerations....and they spec excessive oil content as well....they are doing a CYA manouver.
Straight synth of any mfgr is well known to promote rust and corrosion if left sitting....that is why the mfgrs spec some castor.

I have been using Castrol 0-20W synth motor oil available at Wal-Mart as an after run/storage oil.
After every flying session I run out the fuel, then remove the plug, open the carb and shoot a bunch of it down the intake with the shaft hole open....about an ounce.
I put this oil in a plastic ketchup bottle I stole out of a skid-row ptomaine tavern.
Then I put a rag over the head and spin the prop with the electric starter.
Put the plug back in and it's ready for the next time.
This oil does not affect the starting next time out....does not gum up etc.
I have a YS 140 Sport pickled up with this stuff now for 4 years and a OS 91 4 stroke for 3 years at least and they are in perfect condition.....I check them about once every 6 months.
Works great!

Dave

I think were adding Castor because of NR recommendations of 10% synthetic 10% castor 10% nitro and the rest alcohol.