easton24

My Feedback: (1)

Sorry brew I have never owned a 55ax so I couldnt advise you. I flew my sd yesterday about 8 times and 2 times today. I am still running my engine rich but seems to be starting to let loose. I started yesterday with a 13-8 apc. I was getting about 10000 rpm. Flew ok but not very impressive. With a max rpm of 16000 i knew i had to get the rpm higher if I wanted to get some speed. I next flew with a 12-8 apc. Rpm went up to about 10600 so a little better. Speed wise I was unable to tell if it was faster. So I then tried a 11-8. I didnt have a apc so ended up using a master airscrew. I got 13600 rpm. Alot better rpm wise but did not improve on speed. I thought with a apc 11-8 the speed would improve. Figured I would end the day there and go to the lhs for some apc props in the 11 inch size. Today I had a 11-8 and 11-9 apc. I went ahead with the 11-9. I got around 11000 to 10800 rpm. I took her up and noticed the speed improved over the 12-8. Even in the windy conditions this plane flies great. So now I am searching for the best prop for this plane and engine combo. Due to this engine being newly released there is not much data out there for what type of props to use. Atleast these 11 inch props are not as expensive as those 14 inch props.

patzane

Thanks guys. I will try to get some better video, my camera guy is a rookie at it. I was not sure how well the video was to come out as it was little windy. I will try to get some slow flight video next time I fly and whatever else people like to see.

Brew that does sound right. I have a new OS 55 on a Viper 500 and I am breaking her in on a 11x7 prop and getting about the same RPM reading on a stock muffler. I running her on the rich side as it new and only have 1 tank through her. Once I get her broken in I will be going to a 10x10.

Brew07

I did not think you could prop that low on the .55 I will have to try. 10x10 should make it scream. I got the Jett incowel muffler for 30 bucks thought I would give it a try they claim 500 if not more rpm gain. If I use this set up in the SD I would have to cut out the front of the cowel to make room for that muffler. I am in pain trying to make up my mind on what motor I should put in. Like I said in one of my posts I have a .61 FX and .55 AX on hand to use in this plane.

easton24

My Feedback: (1)

My thinking is if you have to cut the cowl anyway might as well put in the strongest motor.

Brew07

So easton you think I should try the 55 instead of the 61. I could get the 75 but I thought I would use what I got. Going to put the SD together today all but the motor till I make up my mind.

patzane

Brew you know how you like to fly. i don't think the 61 would give you a big big big speed difference than the 55. i know it work, try the 55 and if you like the speed stay with it. if no go head a bolt a 75 on nose. you can move things around with the 75 so you would not to add dead weight.

i just finish my Great Planes Viper500 with an OS 55. My total weight without fuel is 3 lbs and 12oz. Going to try 10x10 prop and work my way down for the best speed.

Brew07

easton did you use the stock muffler with the 75AX? I want the speed so I may bite the bullet and get the 75 just would like to know if I need the pitts mufflet or not. Thanks

patzane

good Brew not you hanging with the big boys. I wish there were a class of racing here in AZ that this little sundowner can enter in I would like to race. No one the fly would race me as they say I would smoke them. there was the guy from the video at would race me, but he was cheating

easton24

My Feedback: (1)

Brew I used the stock muffler. Oh by the way nice video Patzane. Looks like you got your sd scooting.

russm

patzane,i have a liltoni out there. have a moki 61 with a straight pipe on it . decent combo. but, i could pull my jett 90lx off one of my tonis here and throw it on out there. i will be back out there in a week. what do you think?

patzane

russm you are correct. It is the AMPS field. Great field and we flying 24\7 there. Russm that sound cool. I fly there about 3-4x weekly. I use to fly on Sat not to much any longer as to many people. PM me i give you my number and we can hook up.

Well I flew the sundowner today with a 11x9 prop. It was not as fast as the 12x8 that I had on her before. I am not a big masterscrew prop person but I put a 11x6 on the 75 and got 13,890 RPM on the ground. I will try that 2morrow and maybe try a 11x7 masterscrew to see it I can get her over 14,000.

JS615

I finally got my os.91 fx on my sundowner,, had to fill in the predrilled mounting holes with dowls and redrilled new ones for the 90 size mount. i will use a slimline pitts muff,, im thinking of using a apc 12x7 prop,,, anyone have a better suggestion on the prop size???

russm

patzane, i will be back in az monday. my dad normally flys mon, wed, and fri mornings. he does not fly on weekends either. his group likes to leave the weekends to the working men. i will bring my jett 90lx with me. looking forward to seeing the sundowner fly. it will be my next purchase with the same combo you have. let the races begin.

roofer

JS615
Does the cowel fit over the 91 fx or did you need to butcher it got a 91 fx + slimline pits on the shelf and was wondering wil it fit the SD maybe a pic if you can - my experiance with the 91 fx I would even go to a 13 x prop and you should stil rev out to max rpm with a 15% + nitro

JS615

i was shocked when i put the cowl on and the engine did not touch the cowl anywhere, it was very close in places but it did not touch,
now i dont have the slimline muff on yet so im not sure if its going to clear the cowl or not? i will find out thursday,... i dont know if the 13x prop will work well or not,, this is a small plane and there is only so much clearance from the prop to the ground, i sure dont want to be mowing alot of grass going down the runway..

patzane

Russm that sounds great. Just llok on my schedule and I am free till 3:00 so let me know what time you like to hook up. Hope to have the sundown ready and I have to put it on the self for a while.

When out to the field and try the 11x6 and 11x7 masterscrew prop and did not like the output is was given so i went back to the prop that gave me the best speed and that was the APC 12x10. Within 3 mins of the flight at 3/4 thro can a sound I never heard before and than the prop flew off eaten the spinner and backplate. I shut her down and dead stick her in which was not a problem. Got the plane to the test stand and this puppy would not turn over. Other guys at the field say the nosie came from the bearing. When got home I took off the motor to exam it little more. I can see loose metal on the cylinder head and the motor did lossen up little. I have not taken the motor apart as I want to see if this falls under the warrent Tower offer on this motor since I had less than a year. If it does not cover I will be upgrading to a OS 91 since it is about the same same of the OS 75 and weight less the the OS 75. The OS 91 with muffler is 1 oz heavier than the Tower 75 which I have on it now so that is not a big deal.

patzane

well I could not wait until tomorrow to hear from Tower so I broke down and got the OS 2c 91 for the Sundowner. I mounted it on as soon got back from the hobby shop and what a surprise. I did not have to cut into the cowl like I did with the Tower 75. It has about 1/4 space all around motor head and cowl. Just like the Tower 75 which I had on there before, I need to use a pitts style muffler as the stock 91 muffler is too long to clear the fuse. Here are the pic of the new OS 91 and the new cowl I already head on hand.

Roofer I know you asked for pic and the OS 91 here it is.

chris8105

My Feedback: (22)

Looks good Pat, that thing should scoot! I just about have myself talked into buy the Sundowner and will more than likely go with the OS 75ax engine for it. I was wondering what diameter dowel rods you guys are using for filling the stock holes on the firewall for the motor mount. And also which new motor mount you were using. Looks like this one should work. http://www3.towerhobbies.com/cgi-bin...&I=LXJ773&P=ML

And one last thing how big of a deal is it when installing the new mount to get everything lined up right so the crank is centered in the hole on the cowl?

Thanks

patzane

Chris if you don't have the OS 75 yet I would say go with the OS 91. It's the same size and the OS 75, plus weights less than the OS 75. Price is a 10 dollar difference between the 2. As for wood dowel it is not very big, I would say way less the a pencil size I took the fuse into the hobby shop so i can get the correct fit. For motor mount I did go with something a little strong than the stock but it was not adjustable I believe some are using the mount that came with the plane which is ok. As for lining everything up to get the correct crank centered it if important, if not your cowl will be off big time are will you be flying without a cowl.

patzane

I will have to do new video now that i have a OS 91 on this bird. i will do some once I get the motor broken in good.

chris8105

My Feedback: (22)

Thanks for the info Pat. I worded that wrong in my previous post about lining up the crank and the meant. What I meant was how big of a pain is it to get it centered. Not how big of a deal it is if it isnt lined up right.

Looking forward to your new video.

Cobra1

My Feedback: (42)

Hey guys, I have been following this thread with interest and here is what I have done. I ordered a custom header from MACS for my YS 60 and installed it with a tuned pipe over the weekend. Here is a few pics of the install. Since the YS is a pumped engine, I also mounted the tank as far back as I could. It is now close to the CG. I installed the receiver up in front of the tank. To get the proper balance I need to build a battery tray above the servos. I will use screws so I can always get to the servos if needed.

As I don't have a aluminum spinner of the correct size yet, I have mounted the included plastic spinner for now. The completed weight is 6.5lbs (digital scale).

As soon as the weather permits - supposed to snow today - I will take it to the field and put it through its paces. With the 11x10 prop I should get around 120mph - more in a dive. I will let you know once I have flown it.

This should be a fun plane to race around the sky and with the removable wings, it fits nicely in the trunk of my hot rod so I can have fun getting to and from the field!

easton24

My Feedback: (1)

Someone asked about a 14 inch diameter prop. The plane will take a 14 inch prop with no problem. I broke in my 75 ax with a 14-6 apc. Also now what I know now I would have put in a 91fx if I had to do it all over again. Now that I know it will fit. Stick the biggest engine that will fit in the cowl and balance that is my opinion. That is if you would like the plane to go as fast as it can.

patzane

Well finish the sundowner today with the OS 91 and a slimline pitts muffler. I have to cut more into the cowl to fit the slimline muffler than I did when I used the brisson muffler. I did take pic, but t he wife has the carmera. I will post pic later tonight.

For people who looking to use the OS 91FX

If you going to use the OS 91 you will have to use a pitts muffler as the stock muffler does not fit. If you like to pretty cowl, beware you will have to cut it for the muffler weather it slimline or brisson.

learjet45xp

I have been following this thread for awhile now and am looking to get a sundowner soon. I have run a .91FX on another plane for a couple years now and all I can say is that im not really that impressed with the motor. I is an absolute dog without some sort of tuned pipe. I have found the best prop for speed is an APC 12x8, but even with a Jett pipe on it, the motor can only spin up to a max static of about 12,500. It does unload pretty well in the air, but also has overheating problems. Without a tuned pipe I could barely manage 11,000 on the same prop. I think if you are looking at the .91FX you must plan on using some sort of tuned pipe. The tuned pipes are so large I am sure they won't fit the sundowner and look nice though. Perhaps a Jett incowl turbo pipe would work...but then you have nearly $300 worth of motor..eh. I dunno, I would like to hear from someone that is running an actual Jett motor or perhaps a nice YS and see what they are getting.

Thats just my opinion on the .91FX take it for what it is...just an opinion.