Sundowner 50 Results. JETT 60 LX
 

SUNDOWNER 50 Test results.

I maidend my SD 50 yesterday. I went with the JETT 60LX high performance set up. http://jettengineering.com/sundowner.html and pretty much followed their setup. I had a mishap on the first flight and the plane went into the trees. But amazingly, there was NO damage. The cowl came loose and melted to the spinner causing the engine to bog then stall on my approach and i didnt have enough speed to make it over the trees onto the runway. Anyway, i put her back in the air with the JETT on a 10x6 apc tuned a little rich to 19000 ground rpm. The first pass was into a 5-8 MPH head wind at 129.7MPH. The second was with the wind at 138.8MPH off a slight dive. This set up is crazy. Tunning was a bit tough but its dialed in now! The Stalker hand held radar was used for all the tests. Later as the wind died, we did numerous level passes with no added tail wind. The results were all in the 135-137 range. I am very impressed with this set up and the best part is that it settles down very nicely for the landing. Also, these were all performed with NO COWL OR SPINNER. So, i cant wait until next weekend to use a 9x8 and have more aerodynamics. hopefully 140+!!!!

RE: Sundowner 50 Results. JETT 60 LX
 

Hi Darren .......

Great report...... sorry about those Leaping trees. They use to grow in Atlanta where I flew for a while too :)

I appreciate you working through the details on the engine. Seems like the results were worth the wait.

Looking forward to seeing more info here at you get a few more flights on it

Bob

RE: Sundowner 50 Results. JETT 60 LX
 

Bob, not a problem. I think my choice for the custom routing of the exhaust wasa a bit too heavy. Dubb just sent me a light weight aluminum pipe and a dubro deflector and everything worked well!!

RE: Sundowner 50 Results. JETT 60 LX
 

Good news!!! We probably just stumbled into the right combination for ours. On another note we broke the nose completely off ours a week ago when we decided to see if it would stay on the table in a 20mph wind. The airplane was apparently not trimmed correctly as it did not pull out of the dive in time. As a result our continued tests for the optimum propeller are on hold.

RE: Sundowner 50 Results. JETT 60 LX
 

Apparently an aircraft disaster of some form is required. Tree..... table...... ground.... I guess they are about the same.

Helsel will fix the plane and it will of course be faster just because it was fixed.

RE: Sundowner 50 Results. JETT 60 LX
 

19000![:-] Got any video of that?

RE: Sundowner 50 Results. JETT 60 LX
 

hopefully i will after this weekend. 19000 with a master airscrew was crazy. the prop tips sounded to be going supersonic. The sound was unexplainable. On the other hand with the apc, the 2 stroke "on the pipe" sound was great. the motor spins so fast, you no longer hear the individual strokes. It just one smooth sound

RE: Sundowner 50 Results. JETT 60 LX
 

Hey guys, I maiden my SD 50 os55. I wasn't satisfied with the speed. Used a 13 x 8 then 12 x 8 prop, things looked a little more promising but my satisfaction level hasn't been peeked. The engine has only had 8 tanks put through it so I'm still in the breaking in mode. Thinking about putting a larger engine in her and using the os55 in the viper 500 when it gets off backorder. Any ideas for the SD for me?

RE: Sundowner 50 Results. JETT 60 LX
 

I was told to try a smaller prop on the 55 like a 10x8. When I get bored with the 55 I will put a magnum 91 2 stroke in for cheap speed.

RE: Sundowner 50 Results. JETT 60 LX
 

Man, that is a whopping prop load for that poor engine! 12x8 is a big load even for a "big block" .60 - typical numbers for a good muffled sport .60/.61 on a 12-6 are 12,500-13,000. Yeah I know the OS specs list it as a candidate.. which means it can turn it without overheating and run nice and quiet like people want these days and what engine manufacturers like to offer. But it doesn't mean you get maximum horsepower from those sizes.

My SWAG would point to something in the order of 10x7 - 10x9, maybe 11-7 or 11-8 tops if you want to keep the rpm down. Just because the .55 is known as a "torquey" doesn't mean it can swing .60-.90 size props and generate all its horsepower. Torque alone does not equal speed - but horsepower does. As a partaker of this forum I trust you are looking for speed, and if so you want to prop the engine closer to maximum horsepower in the air. Somewhere on this forum I bet there is more data to be found, but I can't find anything useful on the 'net in a quick look. I am going to presume the peak horsepower point for this guy is in the 14,000-15,000 range, someone please jump in and correct me if I am out of kilter.

Some numbers I saw quoted for the .55AX:

10-8, stock muffler less baffle, 13,600
10-9, ditto , 12,900
10-7, Ultra Thrust muffler , 15,500

None of these rpm numbers are excessive or even "high" so I see no harm in testing down to these sizes for the best candidate. Prop, engine, and airframe are a system, and IMHO you are overpropping the engine and hoping for speed but the prop is holding it back.

MJD

RE: Sundowner 50 Results. JETT 60 LX
 

WAY too much prop......... it is a 55 not a 75 !!

Just the 13" disk area out there is like having a big anchor on it.

9x8, 10x7, 10x8, 11x6 the largest

You want the engine turning over 13,000 at ground peak rpm. Preferable over 14,000 - up to 14,500 rpm

Bolt a 10x7 on it and give it a shot. It will not be rocket fast, but it will be a LOT faster than what you saw with a 12x8.

RE: Sundowner 50 Results. JETT 60 LX
 

Yeah I have found the APC 10 x 8 to be my favorite prop on the .55ax. The 10 x 7 allows it to rev alittle better but the 10 x 8 gave me about 5 more mph. Good luck and try one of the mentioned props... 10 x 7 ... 10 x 8

Justin

RE: Sundowner 50 Results. JETT 60 LX
 

since a lot of folks have asked, I will get the part numbers for the exhaust extention and the aluminum tube used for the exhaust extender. Should be posted soon.

RE: Sundowner 50 Results. JETT 60 LX
 

Darren....

Manage to get any more air time on the bird ?

Bob

RE: Sundowner 50 Results. JETT 60 LX
 

Bob,

Not yet, waiting on the new cowl and spinner. Should have it up this weekend. On a side note, i did fly a great planes revolver this weekend with a 55ax and pits muffler. That thing was way faster than i thought. It was constant at 105-107 mph passes!! i was pretty impressed

RE: Sundowner 50 Results. JETT 60 LX
 

has any body put a jett 60lx in a revolver yet?

RE: Sundowner 50 Results. JETT 60 LX
 

not that i have heard about. finished my s.d.50 w/ a 75ax-pitts muffler a week ago. excellent plane. it flys a lot like the revolver. about the same size, weight etc... a little faster w/ the same engine setup. the sd50 that is. the problem i see w/ the sd50-60lx setup would be with the muffler fit. you would have to do a simmler setup like the sd50, or the turbo muffler by jett. not sure i would want to loose the gold muffler to the turbo type. probably loose to many rpm`s.

RE: Sundowner 50 Results. JETT 60 LX
 

yeah, Russ is right there...

The Revolver would do best with a SJ-50 probably.... but from what I have seen the plane is not very friendly when it comes to a muffler installation. The 60LX would be the same installation issue. You can't use any muffler extensions with that version.

RE: Sundowner 50 Results. JETT 60 LX
 

mistake above. meant to say, problem i see w/ the revolver-60lx setup.

RE: Sundowner 50 Results. JETT 60 LX
 

i asked about the revolver because i have one and my friend has the sundowner 50 and we both have o.s.61fx and the revolver is faster and more acrobatic. thats why i was wondering about the jett 60lx.

RE: Sundowner 50 Results. JETT 60 LX
 

Maidened my SD yesterday, havn't put a gun on it but it screams. I am running 9300RPM with a 14 x 8 and a Hacker B40-12L and 5000 6 cell lipo. I had to modify the frame a bit to fit the battery, I hope to not fold her. Awsome plane.

RE: Sundowner 50 Results. JETT 60 LX
 

I found out the hard way that a .55ax is just as fast as a .91fx plus the 91 fx uses twice as much fuel. I bought a .91fx to put on my Pulse xt 40. My pulse xt40 does 115+ with a 55ax and gets 15 mins flying time. I put the .91fx on there and it was no faster and only flys for 6-7 minutes. [:o] Don't get me wrong the .91fx is a great motor but I fill like the .55ax is just as fast(If not faster) plus you get alot more fly time.

RE: Sundowner 50 Results. JETT 60 LX
 

I still like to see video with this Jett 60

RE: Sundowner 50 Results. JETT 60 LX
 

I will hassle Dub and Mike some more on it...

The plane broke when the wind blew it off the workbench last time. Firewall fell off. But I think Mike has it fixed.

They have been busy getting ready for the NATS