Interesting report on the fuel blend - sounds extremely promising!

I can't believe how expensive that AVGAS is!!![X(]

Oh, wait, 30% nitro glow fuel is how much??

My SAP 180 is working so well with 89 octane pump gas that I am loath to mess with it, but wondering how much better it would be without the 10% ethanol. I have a marina nearby and seem to recall reading or hearing that boat gas doesn't have ethanol.

As my funky schedule has it, I am off tomorrow and flying (the wind is forecast to subside) and will try the 16x12 pattern prop, and perhaps some 93 octane pump gas. I have a spare 1-gallon fuel container that happens to be empty at the moment.

OK, well, it is very satisfying to see that we have a totally working and mimimal-maintenance setup and have the luxury of experimenting a little.

I would venture a guess that we will see a LOT more of these engines in pattern next year!

Bob,

I am very interested in your findings with 93 octane pump gas. I don't think the engine will have any problems with the 16x12...it turned the 17x12 at least as well as any other 2 stroke I've had and definitely a little more rpms than I wanted. Temptress is rather low drag airframe so it picks up speed fast.

I have a 16.5x13 apc from 8 or 9 years ago that I used on the webra 145 and 160 during break in. I don't really want to go to a 13" pitch (maybe on the 3 blade) because speed gets a little out of control. Had that problem with the glow 2 strokes too. The SAP actually outrevs the glow engines which just means even more speed. Sound would be very nice though so it's just another experiment.

I may have found the problem with sagging when turningthe 18x12 hybrid...I think the vent was getting blocked just enough to cause a problem. Regardless, that prop trimmed to around 17.5" should work fine. Yet another experiment.

Electric is making great inroad into pattern as I had predicted 7 or 8 years ago when I saw an early large electric model perform with early lipos. No it wasn't Jason Shulman...he came about a year after that. Now I hear that you can buy a 10s set of Zippy lipos for pattern at under 90$. And guys are reporting at least 40 cycles so far. Point is that electric pattern is finally competing well with some wet power set-ups regarding cost. However, the SAP engine with it's lowest costs all around will probably never be equaled. Cost per flight is..what...15c per flight?? Also, I think that when guys see how easy the table manners of this engine are they would possibly consider it. Just love those 1 flip starts. Just the ticket for me since I hate starters

BTW I decided that I will attend next Saturday's contest. Hope to see you there

Ethanol has inherently less power than iso-octane (the main ingredient in gasoline). I recall reading somewhere that 10% ethanol pump gas has about 95% the power of non-alcohol bearing gasoline. Might have read that in Wikipedia (a wealth of info on gasoline in this free source)

Short of increasing compression and using 100UL or LL to get more power, this should be a simple experiment to see if pure gasoline indeed outperforms the 90-10 mix in this application.

Increasing compression is not necessarily an answer.... it may actually hurt the easy field manners of the engine. It might get very finicky and that wouldn't help anything. Curious to know if Todd has tried that tho

Matt,

Well I sold my Focus Sport w/YS 110 so I guess I'm all-in, having already ordered another SAP 180. In the future, I expect to own nothing larger than a .46 2C or a .91 4C, glow, and when those wear out... maybe smaller electrics (Vanquish, Sequence) for practice at the local field where glow power may soon be extinct.

It's still pretty windy here this morning. Maybe it'll calm down a bit later today and I can get in some practice and try out the 16x12, but I've got to say that there's something special about the 15.5x12W and I doubt it will be bested. It hits a very nice sweet spot wrt noise, thrust and speed.

I have the extra 15.5x12's from Graves and I'll bring one for you to try at Jackson ...IF... I can make it.[&o] I have hit a very bad snag with work, which I'll explain by way of e-mail to you, Rick W, Ed A and Anthony R. I should know later today whether it's a go or no-go.

Here is the math; Gasoline has 115,000 BTU/gal, ethanol has 75,700 BTU/gal. So, for a 90-10 mix, you have 0.9 x 115,000 + 0.1 x 75700=111070 BTU/gal. 111070 / 115000 = .966 or 3.4% less BTU/gal than 100% gasoline. The entire ethanol thing is a big political scam, but that is a different topic.

Man, is that a mouthful of truth. Ethanol as we now know it would not exist without subsidies (tax dollars) because it is not economically feasible on its own. The simple fact is that it takes 7 units of energy to produce 6 equivalent units of corn-derived ethanol energy.

Something wrong with that equation. I hope cellulosic ethanol (using enzymes to break down any plant waste) can prove to be truly economical.

There was a MAN article within the last few months on the practicality of running glow engines on ethanol fuels, and the bottom line is... it isn't. Don't think we will be running our SAP-180's on ethanol anytime soon. Methanol boost, maybe?

So, next time I am at the track (NHMS) playing with cars, I will bring home some good ole' NASCAR/ Sunoco 100 octane no lead, 100% gasoline, for the planes and gain some "free" power.

You can feed a person for a year with the corn it takes to fill your gas tank! ETOH in your gas tank, (car or airplane) as stated earlier , is a "Big Political Scam"! ETOH robs efficiency! I think the better numbers some of us are seeing with the avgas can be attributed to the fact that it contains 0% ETOH. If you can find pump gas with no alchohol, buy it and fly it and I am pretty sure you'll be surprised.
This info comes from my PHD chemist flying buddy and my experience trying to get gas milage from my car.
Let us know where you can get the real gasoline.
Thanks,
RC

By the time I got done pecking this out, you smart guys already stole my thunder.. It looks like we are all on the same page! BRAVO!

Rick,

What makes Avgas so appealing to me other than the free power, is several fold:
Avgas must conform to FAA standard and is the same formula whether you buy it in Alaska or Florida....must be very consistent everywhere in the country. Can't state that with any certainty about autogas which is basically at the mercy of the local blender
Avgas has practically no smell and I really like that. Autogas isn't too terribly objectionable smellwise, but why smell the stinky stuff?
Avgas has a much much longer expiration date than autogas...not that we will keep it for 6-12 months, but it's good to know that you can. It simply buys usage margin.

About the only negative is the cost which is highly variable. A quick search on-line revealed prices for a low of 4.40 (from my local airport, lucky me) to a high of 6. Still a far cry from glow fuel, any type

I wonder what gains you could get with an oxygenated fuel such as VP Fuels Q16?

I think that there is some documented evidence that methanol works pretty well as both an energy booster and oxygenator to gasoline (isooctane and heptane mix for the most part). The problem with methanol that I have is that if we start to use this as additive, then some of the maintenance benefit goes away. I'd suspect that bearing problems would return for example. I'm not sure that it's something I'd want to do long term....as an experiment to see, then no problem

The maintenance issue is a good point. Methanol will attract moisture and quickly cause corrosion of any metal parts, and could hurt the carb seals and diaphragms depending on the materials used to make them. That is one problem the E-85 type fuel is causing in vehicles not specifically designed to run on it.

Just in case anybody is arriving late at the party and getting the impression that it takes a special brew to extract exceptional performance from the SAP 180, rest assured that excellent power is available with 87- or 89-octane pump gas, even with 10% ethanol mandated in this region of the country. I am using 89 octane pump gas, and with an APC 15.5x12W (my favorite prop thus far) and the ES 30G tuned pipe, performance with my 10.5 lb Focus II is absolutely superb.

Took delivery of my second SAP-180HP today, Serial #600! For my next pattern plane (whatever it might be) I already have the Macs header and will soon order another ES 30G pipe, and I also have the Tech-Aero IBEC and switch/reg and a couple of servos and some of the linkage bits. Got to build another soft mount.

I agree! The video I made that showed it spinning a Vess 18-6 at 9500 was Mobil 87 octane winter gas with 40:1 B&S oil from my local hardware store. It is what I was using in my leaf blower from last Fall. If I can't get 10K on NASCAR gas with Royal Purple syn at 80:1 then I am going back to the cheap stuff.

Good Point!!!

We have an excellent recipe already that we posted a page or two ago for piped set-up of the SAP. The rest is gravy as far as I am concerned. None of the exotic combos we are discussing have more than a few tankfuls under their belt. The 87-89 octane recipe has several gallons under its belt. If we were to look at the Sport thread on the SAP, then there's maybe 50 gallons total of the 87-89 stuff

I looked back through the thread but I didn't find the information on the turbo hose. 

Can you post a link for your source of turbo hose and/ or specs?

Thanks

Direct link: [link=http://www.siliconehose.com/commerce/ccp11370-870id4-ply-silicone-saej20-compliantgl-c40-087.htm]Silicone Turbo Hose[/link] Look under the "Categories" list on the left, at the bottom is "silicone turbo hose". Get the .870" inside diameter stuff, which sells for 83 cents per inch.

Also search this thread for posts about the JB Weld lip I made for the pipe, and also Matt's posts on the button-head screws for the header, which all keep the hose from slipping.

[link=http://www.rcuniverse.com/forum/fb.asp?m=9623509]JB Weld Lip[/link] on the ES 30G pipe (Hmm... I posted it only on the Sport thread)

[link=http://www.rcuniverse.com/forum/fb.asp?m=9645509]Matt's button head screws[/link] on the header.

Although the turbo hose holds up to heat fairly well, it will likely greatly extend its life if it is shielded as much as possible from direct exhaust gases. I am using an [link=http://www.rcuniverse.com/forum/fb.asp?m=9687199]aluminum spacer[/link] made from a 1-inch length of .875" OD wing tube, inserted into the turbo hose before installing. Using this, the exposed area of the turbo hose is very small, no more than 1/32" total.

Matt can update you on his results with the [link=http://www.rcuniverse.com/forum/fb.asp?m=9694367]Teflon PTFE coupler[/link] he is using now. For me, the silicone turbo hose is working extremely well, but it requires doing it the way we've figured out by trial-and-error.

If you figure out another way to do it or another coupler material, it's always nice to add to the database!

As Bob suggested, here's an update on the Teflon coupler.

It is holding up well so far after 15 tankfuls (1 gallon). I originally also used an ally spacer under the PTFE, as Bob uses under the turbo hose. It turned out that this spacer just couldn't be held tightly enough under the PTFE and slid back, making a racket during flying (hit against the pipe stem). After the first day of flying I removed the spacer and have flown without it ever since. I left the 1" separation space between the pipe and header tho. No problems after about a dozen or so flights.

I am sure that eventually the teflon will burn through...it is rated for 500F continuous service and I am sure the exhaust gas is hotter than that. But it is fully exposed to cooling air so it may be fine for quite some time.

Minimally, there are two coupler solutions as indicated. It's a good idea to use the ally spacer under the turbo hose. Silicone rubber holds it in place fine. It may not be as good an idea to use it under the teflon...it's impractical, noisy. If you decide on the teflon, get the 1/16" wall material X 7/8" ID. Must use some type of bump on both the header and the pipe stem to keep it from sliding apart. The button heads work well and the 20 awg stainless wire holds great and is light.

If you have clamps of the correct size use those. I don't reccommend worm gear clamps... one could easily overtorque the pipe and destroy it. Use spring types

I can confirm Matt's nix on the worm gear clamps. My ES pipe's throat is a bit out of round because of my use of them during the coupler experimentation period. Fortunately the turbo hose's malleability compensates for this nicely and leakage past the zip ties is extremely minimal, perhaps 3-4 drops of oil from exhaust residue after several flights.

On the prop front, I got to try the 16x12 pattern prop today and it worked very well. It delivers performance that is extremely close to that of the 15.5x12W. I don't know if it is cold, hard objectivity or sentimental loyalty influencing my preference, but I think the edge still goes to the 15.5x12W, but only by a whisker. Both props are very quiet - and totally acceptable - in the air compared to the 18.1x10, but the 15.5x12W is a bit more 'torque-y' and a smidge quieter. Perhaps this is because - when you look at the props' side profiles - the 15.5x12W has a bit more of its pitch at the root.

But to be honest, if someone were to install one of those two props and not tell me which one it was, I probably would not be able to figure it out based on performance and noise - they're both excellent, with unlimited vertical.

I have tried to get good results with the 17x12 pattern and the 17x12W, but for me they have just not delivered the authority in vertical, sagging after a while, as reported earlier by Matt. Not horrible, just clearly not as good as the smaller-diameter props.

Matt, I'll have both props for you to try when I'm in Jackson this Saturday. Developments broke my way at work and so I will be able to make it.

Flew the Extreme Flight Extra 300 78" tonight with the pipe. It is simply an incredible flying plane...I have it setup for 3D and even on the first flight I was quite comfortable with it after 5 minutes! Did some aerobatics with it and it was simply sweet! I was very happy!

The engine powers it very nicely. The Extra with the SAP-180HP and everything in mine came up fully loaded, ready to fly at 11.5 pounds.

I have some heavy duty grey silicon hose (about .200" wall) on mine with about a .100" gap on the pipe and so far so good...but only have 1 flight on it and some running time on the ground. I used 2 rivets on each tube (side)...which I was not nuts about right now...but will figure something out really nice in the next few weeks. Still have a ton of other new parts on the burner.

Anyway...it's taching 9500 rpm on the ground with the special 3D prop which is 18.5 inch in diameter...it pulls unbelievably well! Will do a pull test sometime soon.

Todd, your baby just loves the pipe!

In the past couple of weeks, I've had guys flying very large and expensive IMAC rigs wowed with the performance of my Focus II with the SAP-180HP. There have been very few fliers who could resist asking "Whoa, what engine is THAT??!!"

The other thing that factors into this equation is the stoichiometric ratio required to combust the different fuels. The Air:Fuel ratio for gasoline is approximately 14.65, while the ratio for ethanol is 9.00.

This means we use 14.65/9.00 = 1.62 times as much ethanol operating at the same rpm setting.

Because we burn 1.62 times as much ethanol the power comes out SLIGHTLY greater in favor of pure ethanol, simply because of the increase in fuel burned.

This assumes burning straight gasoline vs. burning straight ethanol and is somewhat simplified of course.

You are correct with your last sentence as well. Ironically ethanol is very cheap to make from sugar cane, and we could import from Brazil cheaply, but Iowa 1) grows corn and 2) nominates presidents. The subsidies for domestic ethanol won't end any time soon...

I greatly appreciate the work of Matt, Ed, Todd, and others on this engine. I love flying pattern planes but don't like messing with/maintaining my YS engines, and I don't appreciate feeding them the 20/20 fuel or 30% heli fuel at over $30/gallon. This thread has provided me with a great amount of food for thought. I am looking at selling my several very nice YS engines to get a Syssa engine, plus the fuel savings over a season or two would cover all the cost of the ES pipe.

~Brett

p.s. the stoichiometric ratio for methanol is 6.0 I believe, which is part of the reason why a glow engine of similar size will produce more power than a gasoline engine, although it burns over twice the fuel in the same amount of time...

Brett,

Exactly right, one needs to burn a lot more fuel to get equivalent output when using alky based fuels. That doesn't matter as much in my view...what matters is the associated cost. Why burn twice the fuel for a given amount of power? If there was some kind of magical improvement in the operation, then okay, maybe I see it and I include the 4 stroke in there. The big negatives to 4 strokes to me is their shake and their fuel. They do give more mid throttle torque, but so what? If I need more output I just advance the throttle a little more. The SAP 180 probably doesn't have the pure output of the YS 170 but isn't far off.

On the SAP, I am getting rid of all my glow stuff and converting over. The field manners of this engine are so good that it simply makes best sense for me to do that. Now that I've experimented enough with pipe, prop, carb and fuel settings and have arrived at a good recipe, it's time to burn fuel.

Not to mention the complexity of the YS engines. I bought a used P-47 with the YS 110S and ran it once, and am thinking of selling it and an OS 120AX to pay for another Syssa for it. Cheap gas, easy fill dry breaks like from Jersey Modeler, no playing with all the pressure lines like the YS, and no ugly muffler hanging out the cowling with the Syssa.

This is exactly my line of thought on the issue. I LOVE engines and think the YS is pure mechanical joy when they run right. However I can guarantee my engines will die in the air if I get them a touch too lean (which is difficult to determine, btw). The cost of the fuel is hard to bear, especially as we are running out of local hobby stores that can/will stock the required fuel. The remaining stores usually have car fuel by the quart, and maybe a gallon or two of 10% Omega or Cool Power, and that is about it.

I was seriously considering converting my YS to spark on glow with a cheap RCEXL ignition and 1/4-32 plug, just to have the tighter control of the ignition point, better starting characteristics, and eliminate the preignition kickback at full throttle, but gave up a few years ago when I moved across the country. I love the handling characteristics and CHEAP flights of my IMAC planes on gas engines.

I recognize the Syssa engine won't quite keep up with the YS 1.70 which is fine with me, as my current plane flies very well with the YS 1.40 (with an APC 15x10) currently installed. The SAP-180 will be a huge increase in power over that. I will likely look for a (used) somewhat larger and draggier airframe when I get a SAP-180, and the Focus II seems to be nearly perfect for it and isn't really prohibitively expensive (it is about the same cost as a decent 50cc IMAC plane).