U Can Do 3D/ engines
 

I'm new to the four stoke deal, and this hobby itself. I'm looking at the Magnum XL 91FS AR the Saito FA-91 S, and the O.S. FS-91 II Surpass. I see that the O.S. has a high rpm of 12000, and the saito of 11500, and the magnum 11000. Is this going to make a difference in performance; as far as hovering and being able to climb out of it with no problem? Also further down the road would I wish that I had the extra 1000 rpm?
Which engine to pick? I'm on somewhat of a limited budget; but I'd rather buy quality and only buy once!


thanks for the help!@

Engine choice
 

All the engines you list will work fine on the plane. See the other threads on this plane for much additional infromation. OS and Saito both have parts readily available. Not sure about the Magnum as there if only one flying locally. Seems to run fine. High end RPM doesn't really tell you anything since the test would need to be made with the same prop and fuel in the same conditions. Good luck.

EXCAP232

U Can Do 3D/ engines
 

If you're on a budget get a Magnum xls .91 two stroke for $150.

If all else is equal 1,000 rpm is a huge difference but the companies numbers are meaningless.

U Can Do 3D/ engines
 

Who has the best price for the magnum. Where can I fond it?

U Can Do 3D/ engines
 

If you're going with Saito then I would get the 100 instead of the 91. The Saito 100 will make more power than all the engines you listed. I don't know if the price is still the same, but I gave $265 shipped for my Saito 100 from Chief Aircraft.

Wade

U Can Do 3D/ engines
 

Quantum and Hobby People both sell the Magnum for ($150) but Quantum has free shipping. You just missed the sale at Hobby People, only $120, sorry.

I have this engine on my UCD and trust me, it's plenty. Comparable to the Saito 100.

The only complaint I have is the muffler back keeps vibrating loose.

U Can Do 3D/ engines
 

You have the magnum 2 stroke. I was talking about the four stroke. the four stroke is only $20 more. wouldn't it be better to go that way :confused:

U Can Do 3D/ engines
 

I have a Magnum XLS-91A 2 stroke on mine and I love it. It will hover at a little over 1/4 throttle. I used lock tite on my muffler to keep it from rotating. It fixed the problem. Otherwise it is a great engine for the price. I am running an APC 15-4w on mine. I don't have RPM numbers though. A 14-6 is good as well.

U Can Do 3D/ engines
 

You can't trust advice from someone named Finnz from Wisconsin. Just kidding of course! :D :D :D Mike, you remember me, you bought the BME 50 from me? Are you still running it?

Wade

U Can Do 3D/ engines
 

No, I sold it with the Edge last Fall. I got a 1/4 scale Decathlon with a ZDZ 40. The BME was great though. I ran about 5 gallons through it and it never have me a problem. How are things with you.

U Can Do 3D/ engines
 

Mike,
Doing fine. How do you like the ZDZ compared to the BME? Which one do you think is the smoothest running? I've heard the ZDZ 40's are powerful engines.

Wade

U Can Do 3D/ engines
 

I like it allot. It is a little smoother than the BME. I only have 5 flights on it. This is the ZDZ 40 Sportsman with reed valves. It doesn't have the power of the Rotory Valve. It flies a 20lb Super Decathlon very scale. I will definitely get another. Maybe the 50.

U Can Do 3D/ engines
 

Dlmob,
Something to keep in mind is the weight. The Saito 100 is very light at 20 ounces. I don't know what the Magnum 4-strokes weigh. I think you'll find the OS 4-strokes are a little heavier than the Saitos. I've heard the Thunder Tiger 4-strokes are really powerful, but I think they are pretty heavy.

U Can Do 3D/ engines
 

Mike,
From what I've been hearing the DA 50 is a real winner. I haven't seen one run but I've seen videos of it, seems to be a stump puller.

Wade

U Can Do 3D/ engines
 

I am trying to resist getting any more big planes. I have the Decathlon, and a 1/4 H9 Cap with a Fox 2.4, the UCD, a Lanier Citabria, and just sold my Ultra Stick 60. I want that new H9 Funtana. Should be out the end of the month. Have you been on my web site lately. Check it out.

www.ros********.com

U Can Do 3D/ engines
 

Dlmob,
I found some engine weights for you:

Magnum XL-91RFS/22.4 ounces. Got this weight from Hobby People's site.

Thunder Tiger F-91S/26.2 ounces. Got this weight from AceHobby's site.

No doubt that the Saito 100 is the lightest. There is no weight savings with the Saito 91, may as well get the 100. The Magnum weight isn't bad if that weight includes the muffler. I think the OS 91 will weigh about the same as the Magnum. The TT is too heavy. No doubt that the Magnum is quite a bit cheaper than the Saitos. Hope this info helps you out a little if you haven't already made up your mind.


Wade

U Can Do 3D/ engines
 

Mike,
I see you've been working on your site, looks great! I think this plane will be a good flier, due out in June:


http://www.extremeflightrc.com/product_html/60Edge.htm

I've in line for one when they get them, will use my Saito 100 on it.



Wade

U Can Do 3D/ engines
 

That is nice. I really like there Yak. A DA 50 would be perfect for it.

U Can Do 3D/ engines
 

Yep, it sure would.

U Can Do 3D/ engines
 

so with being on a budget . would it be a 90 2stroke or save for a little bit and get a 100 4 stroke. Also keeping in mind I'll be using the engine for later models as I progress down the line. :stupid:

U Can Do 3D/ engines
 

For the money you can't beat the Magnum 2 stroke .91 for $150. I am running a 15x4W APC on mine and with about a gallon through it , it peaks at 10,900 on 10% fuel with the stock muffler/no baffle.

The first tank peaked at 9,700 and it keeps getting better.

The Saito 100 won't beat those numbers but some people just love the 4-strokes. I prefer the 2 strokes, both will do the job.

If you go the 4 stroke route, get the 100 not a .91

U Can Do 3D/ engines
 

geoHarry,
I am going to have to disagree with you. I was turning an APC 16x4W at 10,300 on my Saito 100.

I was getting the same RPM's with a Zinger 16x5, with quicker spool up than the APC(the Spool up is negligible w the APC, but noticably less with the Zinger).

But of course you do pay for the extra power and 4-stroke sound.

Gotta love the putta-putta.

U Can Do 3D/ engines
 

I really can't compare your numbers to mine.

16x4w 10,300 yours

15x4W 10,900 mine

fuel?


hard to compare but they look similar to me :D

U Can Do 3D/ engines
 

Well I guess the problem is that you wouldn't want to put a 15x4w on a Saito 100, cause it would over-rev. I am just saying I don't think the RPM's/Throttle response would be the same on a Magnum 91 2-stroke running a 16x4w.

U Can Do 3D/ engines
 

2-stroke versus 4-stroke, they both have their advantages and disadvantages. 2-strokes are simpler in design and cheaper to buy. 4-strokes characteristically have more torque, especially at lower rpms, swing a bigger prop more easily, have that cool sound, and seem to be more fuel efficient. Both have great throttle response if adjusted and propped properly, but the 4-strokes seem to have an edge here. The Saito 100 is very light, and I think any .91 size 2-stroke will be about the same weight so this isn't an issue. One drawback to the 4-stroke is you may occasionally have to adjust the valves, but it only takes a few minutes to do. I personally would rather have a Saito 100 on the UCD3D if I could afford it. If you look at all the posts here this engine is definitely the most popular choice for this plane. Dozens and dozens of people can't be wrong. If you want to do a lot of hovering around then I think the 4-stroke is the best choice. I think 2-strokes are great engines as are the 4-strokes, but the Saito 100 would be hard to beat on the UCD. The Saito 100 is a very popular engine, so the resale value would probably be very good if you ever wanted to sell it. The Saito has a 3 year warranty, pretty nice since it's longer than most. This is my opinion, and I'm sticking to it! Sorry for the rambling on. :D

Wade

U Can Do 3D/ engines
 

Bla Bla Bla

U Can Do 3D/ engines
 

Yeah yeah yeah :D

U Can Do 3D/ engines
 

was trying to decide between a .61 ST 2 stroke or a 1.20 YS 4 stroke which I have lying around...thinking more towards the former because it clearly says the 1.20 is too much for it....but at the same time it won't hover too well with a .61....darn....I wasn't planning on buying another engine...

U Can Do 3D/ engines
 

R/C,

I hate to say it, but you will not be satisfied with the performance of the .61 on a UCD......I'm on engine #3 on mine, started with a lightweight .80 four stroke, would hover, but close to full throttle and slow pullout. Then went with an OS91 FX, pullout was great, power was great, but you got an additional 4 oz of goop on the wing from the 91 exhaust. I was also able to go from a 14/4 APC to a 15/4 or 16/4 APC. Engine #3, which hopefully will be test flown tomorrow (weather permitting) is a saito 150 (I know, overkill :D :D :D, but I think this will be the closest TOC type package in a small frame. Power to weight ratio should be between 2-1 or 2.25-1. Fuel consumption should be less than the 91fx, giving me about 10-12 minutes of 1/4-1/2 throttle for just about anything.


You can use anything on this airframe, as long as you do some reinforcement (where GP should have put it in the first place), and remember that the throttle stick is the one on the left. The ONLY time you should be close to full throttle with this plane is while panicing out of a hover. Go with the YS, you will not be sorry...>:D

Steve

U Can Do 3D/ engines
 

ehm....I fly mode 1...but thanks for the pointers...I HATE having to change engines.....

U Can Do 3D/ engines
 

stevezero..anyupdates on you new engine setup?....what mods were you reffering to?...wing and gear area reinforcements?

U Can Do 3D/ engines
 

R/C,

I havent been able to fly it yet with the 150. I havent put the bearings in yet, due to being under the weather, and getting the popup camper ready for the trip to the Joe Nall on Thursday. 25mph winds havent added to the desire to fly either. I have beefed up the landing gear area with some epoxy, and a little bit of stock, but didnt want to go too beefy and risk doing severe damage on a hard landing. I tore the entire block out on a botched harrier landing when I had the 91 on it, and it came out very cleanly, so the repair was easy. The firewall is pinned, with a little bit of tri-stock added. I've also threadlocked all machine screws so they dont vibrate out. I'm stuck going out of town mon-wed, but might take the fuse with me to work on while I'm stuck in the hotel.

I've also monokoted the hingelines on all surfaces on both sides, so flutter, even at high speeds will not be a problem. I put tail wires on it right from the get go, and have no flex in the tail at all.

I've put my battery all the way in the rear of the fuse, right in front of the servos. It's a small nimh 1600 pack, so if i need a little more weight, I'll put the 5 cell 2500 nimh pack in there.


The neat thing about the saitos is that there is only 1mm difference in the 120 and 150, so the cowl fits cleanly and lines up on the stripes very nicely. My saito isnt brand new, so it doesnt have all the oomph of a new one. If I were going with a new engine, I'd put either a saito 100 or a saito 120 on it. I've seen one fly with a saito 120, and one with an os 120 four stroke, and both were very impressive. The power was where you needed it, at the low end of the throttle, unlike the 91fx. It was just a pain trying to prop it.

I'll try to post a couple of pics of the engine install when I get back into town.

Steve

Steve

Saito 150 install
 

Here are a couple of shots of the saito 150 on the nose of the UCD. The cowl wraps totally around it, very clean installation. I'll try to button the cowl up and take a pic of it this afternoon. That is an APC 17/6 prop on it, and I have yet to take it over half throttle out of shear fear on the ground. LOLOL. I still have some tank issues I need to address. I am going to do the floor mod and drop the tank that people are doing in the UCD thread. Still havent flown it with this engine yet, been down at the Joe Nall (what a hoot that was)

Steve

U Can Do 3D/ engines
 

Prop clearance is still well over 2 inches. If it sags on hard landings, then it will get a spreader bar, or carbon gear. I will weigh everything and compare it to the weight of the 91 fx. It balances laterally much better (had to put a bunch of lead on the right wingtip to balance it due to the os muffler). A 5 cell 1000 mah nimh battery pack is resting just forward of the rear servos. Might not have to add any lead at all to the fuse (maybe 1/2 - 1 oz) I wish I would have gone with standard size servos instead of the minis on the elevators, would have given me the extra weight without all the cutting and gluing to hold the 225's.

Steve

U Can Do 3D/ engines
 

Make sure you have enough openings in the cowl to let the air out. With the muffler blocking the main outlet like that you might not have enough cooling air flow.

U Can Do 3D/ engines
 

YS 110. Spins a 16x8 atover 9500 I think. Same weight as the YS 91.

U Can Do 3D/ engines
 

I've got plenty of openings in the cowl. Both cheeks are open to cool the case, and I have a large opening at the bottom of the cowl, and at the bottom front of the cowl to cool the head. There is still alot of room for air to pass over and exit down the bottom.

U Can Do 3D/ engines
 

What about a GMS 120??? would this be too much for the UCD??