Help with engine selection
 

Okay, i have been looking at alot of engines but can't seem to make up my mind for a funtanta x50.

It currently has a OS FL 70 turning an apc 14-4 prop about 9300 or an apc 13-4 about 10,500.
The wieght is 18.5 ounces and is balanced perfectly with no additional wieght. I originally looked at saito 91/100 but canceled them out because of the possible shaking it would cause on this airframe. The 70 shakes it enough the way it is. I also was looking at the os surpass 91 4c and the os 91fx 2c. Both would provide more than enough power but an extra 6 ounces of wieght would be problematic and very difficult to balanced considering tha battery is already pretty far back in the fuse. So i have come down to tow engines, the saito 82 and the os 55ax. I understand that there is really no comparison power wise between these engines and saito (given the funds) would be the way to go. But, my os fl 70 would hang this plane, wich is weighed in at around 5.5 pounds, at about 65-70 percent throttle on the apc 13-4 turning 10,300. Now, i have heard of the os 55 ax turning a 13-4 in the mid 12,000's. If this is true it would be putting out an extra 2000 or so rpm's. So would this engine be putting out more static thrust than my fl 70? Would it hover my x50 given these numbers. I am also hopingm, for those of you who have the 55 ax, that transition is good

The benifits of the os 55 ax would be (and please correct me if i am wrong)
100 dollars cheaper than saito
better idle (nothing could possibly be worse than my fl 70 wich idles okay but once the engine is run for a long period of time (above idle) it simply will not return to idle and it becomes very difficult to land)
same weight as my fl so there will be no change in weight or balance
more power and rpms = more thrust
alot less shakes than a 4c
I hope better fuel economy ( my 46 ax will take about 13 minutes to burn through a 8 ounce tank at fuel throttle, and my flights are easily 20 minutes long. My fl burns through a 11 ounce tank of 30 heli in only 11 minutes, even after it was fully broken in and leaned out properly)

Benefits of Saito would probabley be
way more power
cooler sound

So basically, i am asking if i will get a performance boost by switching to a os 55 ax.

RE: Help with engine selection
 

Few engines idle better than a properly set up Saito.

RE: Help with engine selection
 

Ya, i am sure that is true, and i am not douting that the saito is a much better engine. I have heard of reliable 2000 rpms on the 55 ax wich, if this is true, that is right wear i like it.
What i would really like to hear is if it will get a performance increase over my FL 70.

BTW, has anybody put a tuned pipe on it or a pits muffler. Pits would sure look cool but how much of a rpm boost would you get from a tuned pipe.

RE: Help with engine selection
 

If it was me, a Saito .82 would be the way to go and it will idle at 2000 rpm no problem. I would wait and let somebody else find out how good the 55 ax is before putting my money out for it. I think the Saito will turn 15/4 prop as well. A friend of mine runs that combination on a Forty size Funtana and really likes it.

RE: Help with engine selection
 

For 3D nothing beats a big 4 stroke. I have a similar type 3D plane to yours and it is awesome with a magnum 91 4 stroke. It has awesome straight out vertical power and torque rolls at a 1/4 throttle. In 3D, torque rolling at 3/4 power is a little underpowered IMO.

One thing I really like about the big 4 stroke is that fact that you can turn a big prop for huge torque. I am not sure what is the most used 3d prop for the OS 55 but I bet its not going to turn a 14X4 like the Saito 82 or the 14X6 that my magnum spins. That low idle with a big prop is great for 3D.

Before I would spend 150 bucks on a OS55 (which I think is WAAAAY overpriced) I would look hard at the magnum 52. $60 cheaper and similar power. I know you mentioned weight... but for the money the magnum 4 stroke is great and it doesnt need expensive high nitro fuel. I got mine on sale for 149 last year and it was by far one of the best rc purchases I have made.

RE: Help with engine selection
 

;)For the use on the Fantana, go SAITO 82! The 55AX won't get it done. They are smooth and run like a watch! I run on 10% and it loves it.

RE: Help with engine selection
 

I have a bunch of engines and a digital scale so I weigh them. In ozs , OS 46 16, OS 50 18, OS 91 surpass 22, Mag 52 2stroke 18, YS 63 18, Saito 91 19.

Fuel consumption at full throttle is about 1 oz per min per cubic inch for 15% nitro. If you burn 30% nitro power goes up about 10% and fuel consumption goes up more, like 30%.

Most 4-stroke engines produce about 1.1 lbs thrust per cubic inch (YS are good for about 1.3) Most 2 strokes are good for 1.2 lbs thrust per cubic inch. The OS 55 probably isn't magic - it will probably produce 1 lb more thrust than the 46. It probably won't like 30% nitro.

You have a 5.5 lb plane, same as my Mojo 60. A Saito 91 flies it nicely, some run Saito 1.25's on the plane. I am not a huge power guy but I don't see a OS 55 on my 5.5 lb 3d plane. I have flown 4 lb 3d planes with an OS 46 and unless my wife loses her job I won't do that in the future. I have a Mojo 40 (4 lbs) with an OS 50 on it and it is just OK. I have another 4 lb plane with a YS 63 on it and like that fine.

I fly with a guy that has a 50x and a Saito 82. Unfortunately he is still fiddling and won't get it flying very soon. It should be ok but not spectacular.

RE: Help with engine selection
 

Gringo Flyer, how does your magnum 91 run? What prop are your running and at what rpm? How badley does it shake?
At 200 dollars, It might just be in my price range :D

RE: Help with engine selection
 

Oh, and what kind of fuel are you using. My goal is to switch to one brand of fuel for all of my engines (I don't have many, right now two 2c and one 4c). I was thinking Omega %15 as a possibility

RE: Help with engine selection
 

CAMBO get off the 30% and go for some reasonable fuel like 10-15% I'm sure OS doesn't recommend 30%. To make it easy Wildcat makes 2-4 cycle blend with 18% oil that will satify most engine waranties. You just don't have your engine tuned right yet. The smaller the nitro % the better the fuel mileage. 10% will do you fine and start with a new F plug. Dial in your low speed better.

Morgan Omega is 30% castor and only 17% total oil. Thats 10% more castor than Wildcat.

RE: Help with engine selection
 

Speedster, i agree that %15 might be better but i need it to get any 3d out of this plane. I am scraping the bottom line in power at the moment and want more power. I have spent a little over a year and 1/2 trying to get this thing running well on the bottom end, i have tried different props, fuels, and glowplugs. Bottom line is this airbleed carb just doesn't perform well for 3d. Wich i why i am seeking a new, and more powerful engine.

RE: Help with engine selection
 

Another option might be a os 91 fx with a pitts muffler

RE: Help with engine selection
 

Well your 1st post said you can hang on 65-70% throttle on a 13x4 so I guessed power wasn't the problem. 13x4 zinger looks like the ticket. And if your low speed is right on air bleed it should block the hole half way . I hate to see flyers sometimes think another $300 engine will fix problem. If I were to bet I'd say your low speed screw is out of whack. my .02

RE: Help with engine selection
 

What i said up there is kind of deceptive, and i apologize for confusion, but pull out is not good. The rpm doesn't change dramatically from 75-100 percent power and pull out is not good at all. When you are sitting there at about 3/4 and you go to full, it takes about 3 seconds for it to even start moving up and even then the upline is very slow. I would really like to grow into this plane and i don't think that i will be able to pull out that well close to the ground.

BTW, the fl 70 has a hard time idling on wood props, apc has idled the best so far. I really don't feel like it is overproped, i just feel that is doesn't have the power for 3d.

RE: Help with engine selection
 

Runs like a champ. Over a year and yet to see the first deadstick. Can idle through a full tank of fuel without sputtering. I run a 14X6 MA and dont remeber my tach numbers. I think it runs right around 10K. Look in the tachometer forum there are numbers there. It does shake but no too badly. If I trim the throttle below the normal idle it will start to vibrate pretty bad before it eventually cuts out.

I know its not the most powerful, coolest looking or the lightest engine out there. The saito 82 would probably win that category. But for 200 or in my case 150 it was a bargain and it runs fantastic.

I think you would be fine on 10% fuel although I havent tried it. I mostly run this engine and a ST90 and both of those engines run fine on 5%. High nitro fuel is pricey here in Argentina.

RE: Help with engine selection
 

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I'm with the Saito .82, .91, 1.00 crowd. You can find good deals on these engines occasionally.

Two-strokes that were not made specifically for low rpm, torquey 3D performance, are not going to have the smaller carb and torque tuned ports that will satisfactorily compete with a glow four-stroke as far as 3D flying is concerned.

While the OS FL-70 is a good engine for what it was designed for - low end beginner four-stroke - it isn't really a good 3D engine. Which you now know. It wasn't advertised to be anything other than an entry level four-stroke engine. It serves that function well.

I lean toward the Saito .82 engines for powering .40-.50 sized two-stroke designed models. I like the low weight, small size and the throttling and power of these engines. Why carry a lot more weight for only a tiny bit more power?

I like the Magnum .91 four-stroke and have a couple myself, but then you are right back to flying something similar to the FL-70. It's not a first string engine power wise and it is heavy. Save the Magnum for other uses. Like the FL-70.

If you really can't afford a Saito or YS at this point, consider the SK-90 two-stroke engine that Kangke sells. It swings a big prop and is ported for low rpm running. From what I have heard (Turk1 & Ed Moorman), it does 3D very well, in spite of being a two-stroke and it will run great on 5 - 10% nitro fuel. Plus you just can't beat the price.


Ed Cregger

RE: Help with engine selection
 

Thanks Ed
I will be able to afford a saito .82 i think. If you could would you get the 82, 91, or 100 for my application.
I would like to take a quik look at the sk-90
could someone post a link

RE: Help with engine selection
 

www.kangkeusa.com
http://www.rcuniverse.com/forum/m_45..._1/key_/tm.htm
http://www.rcuniverse.com/forum/fb.asp?m=4903083&key=
By the way Ed,I dont have a SK 90 yet,neither 3D but Im using SK 50 s for sport and great engines for my no nitro fuel.

RE: Help with engine selection
 

Nice price on that engine, what prop would you stick on it, and how much thrust would it produce?

RE: Help with engine selection
 

Wow, i could get one with a pitts muffler for like 130 dollars
What would be the all up weight with the muffler they sell.

Do you think that this engine would provide sufficient power for 3d.
I am assuming that if the engine ways about 25oz than the plane will come in at 6.3 pounds.

I really would like to go with a cheaper engine. If i burn all of my money up on the saito than i will not be able to get the high torque servos i have always wanted. [:o]

RE: Help with engine selection
 

From http://www.kangkeusa.com
If you click the 'SK Engines' link, then the 'Specifications' button it takes you here:
http://www.kangkeusa.com/Engines/specs-sk.htm

The chart gives the inmpression that the 90 will turn a 13x8 prop around 10400 rpm.

If that's true, it seems like it should turn a 14x6 or 15x4 pretty well.

I do not have any sort of thrust calculator at work, but a 14x6 or 15x4 in the mid 10k range should put out quite a bit more thrust than a 13x4 at about the same rpm.

RE: Help with engine selection
 

Well i did a search and it looks like this engine can turn a 15-6 in the 10k range. That is a fantastic number IMO. Weight might be a problem with it comming in at 26 ounces. 7
ounces heavier than my fl. I would like to get a thrust calculation in there also, just to be sure that this engine could sufficiently power this plane.

RE: Help with engine selection
 

Does anybody know of a mount that will fit the funtana mounting dimensions and fit the sk 91 at the same time

RE: Help with engine selection
 

I strongly recommend you to read Ed Moorman s comments on that engine I gave the link above on SK engines thread.You can find props and performance of that engine.

RE: Help with engine selection
 

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For powering .40-.50 two-stroke sized models, I would go with the Saito .82. For powering two-stroke .60 sized models, I would go with the Saito 1.00.


Ed Cregger

RE: Help with engine selection
 

Thanks Turk 1, I read through the whole thread, and did searches on other forums. It really does look like this would be a solid 3d engine.
So far, nobody had tried a 16-4, could it if it can turn a 15-8.

BTW, how much thrust would i get out of this 90 turning a 15-6 or 8 prop close to 10,000?

Also, thanks for the comment Ed, if i go with saito, it will be the saito 82.

At the moment I am between the saito 82 and the Sk 91 but am leaning toward the sk because of the price.

RE: Help with engine selection
 

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Being a larger two-stroke, you can bet that the SK .91 will be considerably more powerful than the Saito .82. Plus it will do it while burning 5% nitro fuel. I'm going to dig mine out and mount it on my Harrier 90, just for kicks.


Ed Cregger

RE: Help with engine selection
 

Do you think omega %10 would be sufficient for this engine?

RE: Help with engine selection
 

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Absolutely.

Turk1 is running his SK engines on 0% nitro and is happy with them.


Ed Cregger

RE: Help with engine selection
 

Also with self mixed full castor industrial(not so pure) methanol fuel.With OS A3 plug.
The important factor here is to choose the load(prop) about recommended RPM s not to overporting,SK tech dept. advises.Then those engines are great torquers and very reliable,never a deadstick.
My W.M Dago Red has flown on second tank with my brand new SK50 just after one tank run for break in on ground.

RE: Help with engine selection
 

So, if i go searching for a 3d prop for this engine what one should i get. It looks like 15-4 is to small but i am not sure that a 16 incher will have enough prop clearence on my funtana.

RE: Help with engine selection
 

Cambo,send an e mail to Ray Nano at Kangke asking for technical info about your needs.I hope thats the better way for you before making mind.
[email protected]