harrymc

radconfun,
Here's my electric setup:
Hacker A50 12S motor
CC 80 ESC
EVO FP5000mAh 6S 22.2v battery
APC-E 12x12 prop
This setup pulls 65 amps, 1425 watts at full throttle static.
Have any of you guys radared your aircraft?

radconfun

Bob, if you dont mind helping me out. what are the big differences between 2 and 4 stroke engines? Whcih do you recommend?

bob27s

My Feedback: (19)

Well, to start with ----- two totally fundimentally different type of engines.

The 4-c are RPM limited. Typically 10,000-12,000 rpm limit due to valve system design.
They deliver more power for each power stroke by typically delivering a longer duration power stroke.
But they only fire every other prop revolution.
Thus they tend to use larger load props to take advantage of the torque, and to keep the rpm down.
Critical for ARF designs --- The exhaust system does not exist, is small, or it is an afterthough.

Performance enhancement comes from supercharging or turbo-charging - putting more fuel and air into the engine.
Fuel inlet and exhaust outlet are completely seperate. Only a slight overlap.
Sometimes fuel injection seperates the air coming in and the liquid fuel coming in - better control of mixture and fuel mixing.
YS 4-c engines use a supercharging method. They pump a LOT of fuel/air for combustion each stroke. Thus they make more power.
Saito and OS are mainly naturally asperated - fuel is sucked into the engine. Fuel delivery is fixed more by geometry.
fuel = energy Power = burned fuel (energy generated or converted) within a given time (at its very basics -lets not get into engine design here..)

2-C engines are Not rpm limited by most design constraints - other than the materials it is made of.
(yes, turn an FP-40 at 20,000 rpm for long and it will break something).
The more rpm's, the higher the developed HP (remember rpm=fuel burned per minute more fuel = more power)
Engines are designed for practicle and specialized applications. Thus their porting and port timing can be taylored.
For high-rpm and light loads from small props, aggressive timing can be used (marine, cars, speed aircraft, ducted fan)
For lower-rpm and larger props, more concervative timing can be used (most sport engines)
Exhaust system is LARGE - we use effective mufflers.

Performance enhancement comes from the EXHAUST side, since intake and exhaust happen essentially a the same time.
A 2-c engine may use a TUNED EXHAUST - to improve engine performance and rpm. They help both the inlet and exhaust at the same time.
Tuned exhausts are large.

The resulting power-to-weight of a tuned 2-c system still tends to exceed the power to weight of a 4-c engine.
But in a different RPM band.

Ok..... to the subject at hand.....

The difference on a sundowner is how you want to install the engine, how you want to fly it, and a personal preference on engine type.

If you can accomodate the 2C engine, you can turn an average size prop and pitch at high rpm.
Small prop diameter + high pitch + high rpm tends to be best speed.
The prop diameter creates a DISK that creates drag. Small prop, less drag. Extremes: ducted fan - no prop disk fast. CL stunt - big prop disk (slow)
Of course, the prop must be balanced for the aircraft, its intended use, AND the engine/exhaust system.
Example here of a 60LX installation, 10x6 prop turning 18,000 ground rpm
or, big block engine - 90LX turning a 10x10 at 16,000 ground rpm
The engine installation to accomodate the engine and exhaust becomes your limiting factor.

Going with 4c --- prop selection is again critical. Use the power differently.
No exhaust system to accomodate.
Small block engine size ---- probably a Saito 82 or YS .63 engine is best. (.46 size crankcase).
If you put in a big block YS110 --- thats monster power with a 13x13 prop (11,000 rpm?)

Quite simply, it comes down to a personal choice.

Looks like this thread has a LOT of great examples and a good variety of options.

radconfun

Wow. Thanks for taking the time to go through that for me. After reading what you have said and the entire thread twice, I think I am going to go with the OS .61 for now. I am also, obviously, a bit of a beginner so I am not looking for the top speed just yet. If I want speed later, I'll upgrade.

patzane

well said Bob. I need to contact you guys about getting a muffler for my OS 91 that is on my Cermark F-16

JS615

Ok i took off my os.91fx, and installed a saito 125 on my sundowner 50,, what would be a good prop for this setup?????

ALO 111

Why the change to the saito?

JS615

I just could not get the os.91fx to run good with the slimline muff, i tried and tried but it would not run consistantly good,, i have had 2 os.91fx in the past 3 years and i have never been able to get one to run good with a pitts muff. maybe its just me,,, but i still need to figure out which prop to run on this saito 125,, im thinking 12x9, 12x10, 12x11,??????????????

dc10capt

just put a Jett 90lx on my sundowner 50 today...with a little cutting of the cowl it works and looks great.......what a speed demon. can't wait to fly again tomorrow...i'm ggoing to test some differrent prop sizes.

learjet45xp

A 90LX !!! Now thats what im talkin about!!

patzane

can somebody buy me one so I can put it on mine :-)) Please

rmenke

My Feedback: (13)

JS615:

Ohhhh. Gonna be mad at myself for this, I am not a OS fan just as I am not a General Motors fan. Will not forgive either, GM for their desiel Cad and OS for their super cheepie berings and sleave material. Back to the subject. The OS design is good, copied a bunch simply because of the original design, including the carb. They are designed for the majorty market place, sport. If you want fast, you gotta pay for the Farrari. Jett, Nelson, Profi. So far, only Jett produces a high quality sport motor capable of go-go rpm, and will still idle better than most sport engines. Yes, I'm a Jett fan, proven to myself that the engines are cheep in the long run simply because of the quality which tends to run foreaver. Not unusual to see Jetts still running very strong after 6 years of hard use. Your would have replaced that OS at least 6 times in that period used in the same manner for the same duration.

To work! First, replumb your tank with all new interior copper and flex fuel line to the carb, carefully leaving 1/8-1/4"clearance at the clunk, and be sure the vent also has clearance. Make another flight to be sure the problem is not corrected. Lets also be sure you have that OS carb pressure cleaned and the idle circut correct. The idle circut will effect the top end on most modern carbs, a happy engine is one that will idle for over a minute and then transition cleanly. Open your carb idle screw 1/8 turn. Start it up and get the high speed needle to where the engine is running cleanly, but still a fine smoke trail. Go to idle, Run her for a minute and then open it up. If she staggers, work the idle and high speed needles until it will transition correctly after a minute of idle. Spend the day if you have to, but get that idle. Then fly. Fixed? I suspect not, but do the idle anyway. Like most glow engines, they don't like their plug stuck in the oil and fuel when inverted. So, install an a OS-F plug and do away with that tentency. Notice I did not say a idle bar plug, only used as a last resort for junk engines. Fixed? No, you may still have the muffler/fuel pressure problem that is obvious. Whats going on is that the pressue from the muffler you are useing is not about the same as the OS muffler it was designed around. So, you have some obvious options. 1. Buy a new cowel and install the original OS muffler like Bob's 27 did. 2. Throw money at pitts muffler systems until you find one that will work with your installation. Different manufacturer designs will give you different pressures to the tank/carb system. They all have different outlet locations and sizes, and worse yet, interior baffels that do not always get installed at the same location. 3. Here we go, save some bucks and work at it. If you do not have a good drill index with drill bits in 1,2,3,4, sequencial sizes, you need one. The pitts muffler nipple should be brass, if not get one. Find the size of the niplle hole, start around .076 which is the size of a YS 60. Drill out the nipple 1 drill size, clean and go fly. Adjust both needles as needed, check idle and go fly. You are going to have to drill on that muffler nipple until the engine is running as it should. A little trinkit of interesting (to me) information. Sorry I dont have a OS 60 or 90. A OS46AX niple opening is .070, a Webra 50 and TT46 , the same .070. 3 sport engines, all the same nipple opening. Now, the Jett 50 size is .046 all per my drill index. I have yet to find any engine, 2 or 4 stroke that transitions and idles as well a a Jett, from the 35 to 90. Sorry I'm sounding like a add for Dub Jett!!!!

Ok, if you cant come up with the bucks for the best overall Jett engine, 60LX in my not so humble opinion, get a Webra 55. Not a 50, or 40 or 60, a 55. Break in per Jett's web site instructions, add apc 10 X 10. Yes the Jett 60 LX will outrun you, but not by a whole bunch. In the meantime, you are lapping the other guys, probably at least twice against the OS types in 10. No No you say? Well, ever run for pinks? I'll even fly it in a Avi-Star trainer!!!

jacks1

CAN SOMEONE PLEASE HELP I WANT THE SUNDOWNER 50 IN THE 120s OR 130s I JUST CRASHED MINE WITH AN OS 61fx WITH A TUNED PIPE AND I STILL WANT MORE SO ANYBODY GOT ANY IDEAS

patzane

Try a YS 91\110 or Jett 91 that should get it up there

Razor-RCU

My Feedback: (50)

Yeah the YS-1.10 would get you close...The Jett-90 is a runner but what is the wing-span of this thing?

patzane

WingSpan is 61' why would the wingspan make a difference

jamesrxx951

i am currently in the process of starting a sundowner 50. i purchased a os 91 engine and spektrum servo's. it sounds like the factory muffler is not an option so i was looking for recomdations for a pitts style muffler. i really don't want something real loud because of neighbors in the area but i might really not have a options for that. i also don't want to cut up the cowl if at all possible and from patzane comments the bission might be the way to go. just looking for recomendations. also what prop is best and what rpms if possible? im just above sea level so it should make good power. thanks for everybody's help.

Yellowsierra02

How fast do you think the sundowner and a Jett 60LX would be. I just ordered a Jett 60LX and Im trying to figure out what kind of plane to put it in. I wish they had a smaller/lighter Sundowner. Like a 50" wingspan and 3-4 pound weight.

bob27s

My Feedback: (19)

There are a couple flying with 60LX power.
No videos or sound data yet to pull doppler, and no radar info to go by.
Only info was "boy this thing moves!"

Dub is building one. Should be in the air this weekend weather permitting. Perhaps we can get some good info in the near future.

Bob

rmenke

My Feedback: (13)

Yessssssssssssssssssssssssssssssssssssssssssssssss ssssssssssssssssssssssssssssss

Could be varley interesting.

jacks1

ok thanks for the help i just ordered a jett 60lx so ill let yall know how it does

Yellowsierra02

Yeah I just got off the Phone with Dub jett. I talked to him about the Sundowner and he said he was actually building/helping his friend with his. He said it should turn out real nice and he really likes the quility of the Sundowner. There using a 60LX in it so it will be nice to see how it turns out. I think he said he's going to post some info on his site about the plane/motor combo when they get the plane done. I guess time will tell. I cant wait.

bob27s

My Feedback: (19)

Here is the sundowner 60LX setup Dub and Mike put together. Pretty much in line with what I described way up earlier in the thread, and similar to the photos posted of another 60LX powered bird.

Dub is going to offer a "sundowner" package that includes the exhaust spacer/angle and an engine mount that accomplishes the rotation and offset from the firewall.

Note how clean this setup is. Muffler enters the fuselage. A baffle/tray/deflector is build inside of the fueslage to enclose the muffler area a bit. Exhaust exits the bottom of the plane. Small cutout is required in the cowl to clear the foward part of the muffler.

More photos once they get it in the air this weekend.

z06kal

I think electric is the way to go for a fast sun downer 50 personally. This plane needs something like a 11x11 or 12x12. It is hard to find an IC engine with the power band to support this size prop at 150mph. My 2 cents anyway.

Yellowsierra02

This is what I was kind of thinking. You would have to have the best of the best nitro motor to keep up with a off the shelf E-flite brushless 46. Then you have the extra weight of the nitro motor so you would have to add weight to the back of the plane. I hope I get proved wrong but this is how Im feeling right now.[] Im hoping the 60lx gives us a chance.