summerwind

i guess leaving well enough alone is best, but us guys do like to tinker eh?
thing is, the last time out i could sense some improvement in the engine, and the speed of the plane keeps me in tune to it, or at least 50 feet ahead of it. my fingers were actually twitching. i never realized that being 55 would have an effect on flying faster than normal planes. when i was in my early 30's a Pylon racer was no challenge at all.
i can't really tell how fast the SD is in flight as i'm watching it and knowing it's every move, but the guys tell me it's screamin well above 125-130.
need to get a radar gun on it.
can hear the windtips whistling though.
i'm thinking the 9x8 would be faster yet.

earlseaholm

We MUST always tinker!!! Never know what you may find out. [8D]
If you would, try the 9-7.5 - then the 10-6 and see if you see any difference.
I am sure it is lower altitude in Fresno than Billings.
Never know - may work better for you.
Your fingers were twitching?? My son AJ is the overall National Q-40 champion, and he shakes like a dog shi_____ razor blades when he fires one up.
He says "that is why I do this gets me pumped up!!"

summerwind

yep being pumped is what makes things fun
i think i use to drive my Dad nuts as if anything called for a .40, a Rossi .65 or OS 61FSR got installed....even dida clipped wing Sig Cub with an OS 240twin once haha.....

i'll give those props a try and see what happens.

gregka

My Feedback: (1)

i am building a sd 50 with a os 55 . i have a macs one piece, trying to decide if the macs pipe will work or if i should just get a jetts pipe. is any one running a macs on a os55 or do u guys know of any one using a macs in a sd50 ooor am i just waisteing my time with the macs

earlseaholm

As I understand it __ the Macs muffler is just that __ a muffler. It has little or no tuning effect.
On the other hand the Jett is a tuned device that will significantly increase the power of your OS.
I would get the Jett, and call Dub to get the correct spacer for the SD.

bob27s

My Feedback: (19)

That is correct. The MACS black muffler is a light-weight muffler, no tuning effect to it.

The Jett muffler and spacer kit is available for the OS. A few OS55/SD combinations flying that I am aware of. Seems to like a 10x8 prop set like that.

Bob

lfinney

My Feedback: (44)

although the macs muffler is quality light weight muffler for a few dollars more you get the jett...

Cratus

My Feedback: (49)

Hey guys...I've been following the thread and wanted to add my pics. After some robust reinforcement on the fuse and firewall, I'm almost finished with my SD 50. I hung a YS 110 with a 14x10 apc prop. I'm guessing she will fly pretty fast...somewhere between 110 and 130 mph but I'm not sure. The YS is a hammer-knocker but the reinforcement should work. I've read a lot about Evos, Saitos and Jetts but not much about the YS. I should maiden her this coming weekend. Other than the engine flying off, I'm concerned about the Dubro 16 0z fuel tank because it tends to expand quite a bit with the 7to 9 lbs of pressure produced by the engine. I used a couple of tie wraps to keep it from expanding too much and pressuring the canopy.

summerwind

this thing is gonna be a smoker.[8D]
i have a YS 110 in a GP Super Skybolt, weighs just under 8 lbs and goes straight up until i decide to pull the stick back to idle...............it's one freakin animal of an engine.
hope you got the firewall reinforced like crazy, if nothing else for your safety.
good luck on the maiden although you won't need it. mine flew right off the board as they say. i think i needed 2 clicks of up and that was it.

taiping

Hey guys, I ordered a sundowner, and i wonder that will you guys recommend a 91fx with pitts or a 95ax with pitts?

earlseaholm

Finally got a chance to fly the SD again last weekend.
Got lucky the throttle servo failed at wide open throttle - fortunately the rest of them kept working. (whew)
The bladder tank worked flawlessly - the mixture didn't change till she quit.

BTW my kid won Q40 AGAIN at the NATS two years in a row. "WOW"

LongRifles Inc.

Well I'm getting closer to finishing my SD50!!  I got the tail feathers on finally.

I did something a little different for the elevator.  I went with an internal pushrod setup for the elevator halves.  I machined up a horn from brass and soldered it to the "U" shaped wire that connects the two elevator surfaces.  From there I ran a DuBro link to a 5/16' hollow carbon rod and straight to the elevator servo mounted on the "driver's side" of the fuse towards the back where the canopy attaches.  It should make for a very rigid setup that will provide very crisp elevator control. (hopefully)  I'm using a true 1:1 linkage ratio so the resolution of the servo  should be pretty linear.

I plan on running some sort of pull/pull arrangement for the rudder.  That servo is mounted in a tray that I made that mounts over the elevator in the centerline of the fuse.  It worked pretty well on the last one of these I built.  (I seem to go through one of these airframes each summer)-sucks!

The Firewall is definitely in need of some reinforcement!  I have a stash of thin Al angle stock that I plan to gusset the sides with and attaching with epoxy and 4/40 screws.  I think it'll be a minimal weight increase while providing some solid rigidity in the event of a nose pick or prolonged vibration.

I'm using a Jett60 like the one from the Jett website.

Good times, good luck.  Wish there were more guys around here into these planes so we could get some racing action going.  I have a buddy with a Dago Red/OS 91 set up that's talking mad chit so it'll be interesting to see who takes the glory when this bugger is done.

Herbs_007

Taiping, i would not recommend any of these motors. I have a .95ax with a Jett muffler, its to heavy, and has heat problems, also you would have to butcher the cowl to fitt a pitts that size. But i must say its certainly does motor thru the sky. I would recommend a motor in the .55 to .61 size range, and with a Jett muffler if you can get one, or better yet get a Jett motor..

Herbs

bhoges17

I just picked up a Sundowner 50 from my buddy with a .95os motor and a 14x8 prop. He never flew it and I did the maiden tonight. Didnt seem very fast to me. Maybe around 100? The motor was reving around 9700rpm. Thought this plane would be much faster. Anyone have any imput on the setup? Was thinking of putting a smaller higher reving motor in.

Herbs_007

Hi,
I use an APC 12x10 with my .95os and a Jett Muffler, and she does about 120-130MPH plus...

summerwind

Earl,

congrats on the kids win................love it when the kids beat the best.

still haven't tried the 10x6, but did switch to a 9x8 and found peak at 18,300 rpm..........it didn't turn this prop at this rpm when out of the box, but i now see why taking time with break-in really pays off.
anyways, i set the 56 off at about 17K on the ground and WOWZA!!!...........the mild howl that the SD makes on HS passes has turned into a wicked whistle.
this thing flat out moves with the Jett 56.
didn't even fly out the full 4 minutes on 2 flights as 4 passes was enough for me
if i do try the 10x6, i think i'm going to go with a Vess tho..........hope it will hold up

bhoges17

Yup need a different prop only getting low 80's with the 14x10. Going to try a 12x10 next thanks.

summerwind

watch this video....had an OS .95 in it..........went like stink

http://www.rcuvideos.com/video/Sundo...own-Engine-sep

bhoges17

I like my Revolver much better. It can knife edge and turns much tighter. I love the look of the Sundowner but its not what I expected. I hope the smaller prop wakes it up.

LongRifles Inc.

Well, good news for Chad. My little SD maidened well last evening.

Mine has the Jett60 set up like on Dubby's website. I've had a few of these planes and this latest is the best so far. TETTRA fuel tanks are the ONLY way to go IMHO. Rock solid! I have a 5.5oz tank. Good for ten laps plus a high speed dive or two. That's IT! so if you go this way just be mindful of your timers! Very compact, light, and easy to assemble. I had a Dub bubble tank before this. I didn't care for it all that much. Great engines!, but the tank isn't for me.

I'm suffering a bit of a lean surge when banking hard in the corners but I have that sorted out now. Raised the tank to get level with the carb, switch to hard lines all the way to the needle valve/carb, and switching over from exhaust to crankcase pressure w/check valve to squeeze the tank.

I learned a bit on the handling too. Finally got this bugger to corner the way I want. it'll bank almost like a formula plane now. It's all about CG and a little creative mixing with the elevator and ailerons.

My engine is taching at 17,600 with a 9x6 apc. This was on 10% powermaster. I'll bring the 15% out this weekend and see if the speed comes up as the engine wasn't unloading in the air quite the way I wanted. It'd spin up really well in a dive, but sounded a little lethargic straight and level. I'm at 3600ft for elevation. Hoping that the snortier fuel and revised delivery setup will allow me to maybe bump up the prop to a 9x7 or maybe even a 9x8.

We shall see.

If any of you guys are coming to the Sturgis Bike Rally, BRING YOUR PLANES!! We have a field right outside of town with a 600' grass strip that's about perfect for little racers!

vertical grimmace

My Feedback: (1)

Thats great to hear Earl. A.J. always kicked ***** in combat and now he is doing it in pylon. Great news.

bhoges17

Did some radar runs today and with my .95 0s and a 12x8 prop spinning about 11,000 downwind hit 110. Id say its probably doing 95-100. a little bummed thought it would be faster. Think a 12x10 would make much difference?

BiggerDanno

I think that it would. The engine has the power to pull the 12x10.

earlseaholm

Yeah - he did pretty good in combat too - Overall Nat champ for two years.
He is leaving Kansas City and moving back north to Rapid City. Now I will get to see him, Michelle and the grandkids more. :-)
May have to sharpen up my flying skills and give him a butt kicking!!!! [8D]

LongRifles Inc.

Wow!

That's great news. I'm in Sturgis and we have a new (developing) RC club here with a 600' runway (grass) If he ever want's to come fly here he's more than welcome. No restrictions, exhaust, speed, turbine, the works. We cator to all of it!

Chad