Anyone have an estimate how long an .049 Surestart will last on 1/3 oz. of fuel? I have an old small square metal tank that is about 1/3 oz. and I'm wondering how long I'll get out of it before I second guess myself and buy a 1 oz. tank. Thanks

Hmmm, well, I usually get 15 to 20 minutes off a 2oz. tank (mileage may vary depending on model), so do the math.

ZZ.

2.5 minutes give or take a couple of minutes.

I would guess maybe 2 minutes. A real accurate answer would be test run it with that tank a few times and time it.

I typically get 6.5 to 7.5 minutes on a 1oz tank with a Surestart depending on the weather and needle position, etc.

Another thing to consider is the prop.

If you run a 6X3 the RPM comes down fairly significantly compared to the "Safety Tip" 5 X 3 and that will affect the duration as well. If it runs 2 minutes on the 5 X 3 it should run at least another minute to minute and a half on the 6 X 3.

Thanks, I'm definitely looking for longer flight time. Maybe something around 10-20 minutes. I'm going to do some more digging in my stuff. I'm always rediscovering things I've put away to use someday.

I generally run a 6x3 and get 3 minutes out of a tanked reedie, which is about 1/4 ounce, so your tank should go about 4 minutes ,,and a 1 oz tank should go 12 minutes roughly...Rog

If glow fuel was made with ethanol instead of methanol wouldn't it need less nitromethane and heat glow plugs better, I've just never heard of it?

Possibly, but it would drive up the cost of the fuel a lot.  The stuff is expensive enough as it is.

I think this question has come up before at RCU and the answer given was that methanol supports the catalytic action, but other alcohols not as well / not at all.

In high performance motor sports, it's always been methanol, methanol, methanol.
Last time I checked it sold for $3.00 / gallon.

With .049s the prop governs the rpm and the fuel economy. It makes no difference whether it's a TD, Medallion, or Babybee....if the same size engine is held to the same load and RPM the mileage will be pretty much identical. This assumes the engine isn't throwing a bunch of fuel out the front bearing.

Not as easy to notice on the smaller engines but nitro percentage has a large affect on fuel use as the nitro bears oxygen which requires a richer needle to keep from being lean. My glow helis will fly almost twice as long on 15% as they do 30% just from where the needle ends up being to get it in tune. Not worth it to me in a situation where I get 8 minutes anyway, but on a backplate tanked reedie you have less options Todd

Another variable just or fun: SPI vs non SPI piston / cylinder combos (Should you decide to sup-it up) also have a noticeable affect on performance / fuel economy.

On the same engine, an SPI setup will need about 3/4 to 1 turn richer needle to account for the extra air ingested by the SPI effect. You get significantly more power (about 1000 rpm's) with the associated increase in fuel consumption. You still get a decent autonomy with the 10 ml tank on the Black Widow but it becomes almost pointless on a Baby Bee's small tank.

Texaco set up?
Texaco is an endurance event and uses bigger props to acheive longer run times. I dont have a clue as to the effects of the head on the endurance. Is it lower compression? additional head shims? I'll watch for an answer too!

True-but in Texaco you're using way bigger props than normal for 049 and holding revs down to 7-8000. Here in NZ we're using APC or GWS electric park flyer props-8x3 or so-some have even tried 9" with varying results.
The 5-fin Texaco head is exactly the same as the std 325 low compression head on the inside. You always have the choice of adding extra gaskets of course, and quite a lot of our guys are running 3 gaskets under the Texaco head. I don't know how much fiddling it is worth getting into with fuel mixtures. 10% or 15% seems to be about the max used here in Texaco.

Back in the 60s and 70's in Class B team race which was completely glow dominated-unlike the smaller classes (FAI and 1/2A) which were diesel dominated, people were using all sorts of weird and wonderfuel brews-containing isopropanol, cumene and various other exotics in the search for greater economy.

The simplest option in this case is simply go to a bigger tank-but if you are constrained by the model geometry to a small tank then perhaps some fuel experimentation is in order. I would expect that 5%-10% isopropanol should not significantly impact on the way the engine runs, but improve fuel economy to a degree. The only caution with isopropanol is to ensure that you get good quality stuff-some of what is sold-'rubbing alcohol' for example is quite 'wet'-containing quite a lot of water.

ChrisM
'ffkiwi'