doublesixes

I'm using an OS .46 AX in my Hyperion Yak 54 40e. It flies great overall but it lacks in 3D. It will pull out of a hover at full throttle but very slowly. Not really reassuring when flying at low altitudes. I've tried different props: 11X5, 12X6 and 13X4. The best by far is the 13X4 because the plane has more authority in any maneuver. You could say it has unlimited vertical but it will climb really slowly. Yawnnnn.......

My question is which of the following 2 alternatives would make the greatest improvement regarding 3D flying.

1. OS .55 AX 2s
2. OS .70 FL 4s

The plane has a wingspan of 138 cms and in its original electric configuration weighs between 2.1 and 2.3 kgs. Mine weighs about 2.2 kgs. It would be helpful if manufacturers would state the thrust of their engines with all possible props. This way this tedious guess work could be minimized and in the end they will end up with happier customers.

XJet

The OS 55AX has gotten a lot of good reviews but why confine yourself to OS?

If you can afford it a Saito 82 would be a much better option. Lots of power and 4-stroke "grunt" that is ideal for 3D.

IMHO, the OS70FL is a fine engine but not exactly a real powerhouse and according to this page only has an airbleed carburetor (not at all good for 3D).

Perhaps the Thunder Tiger 75FS would be a cheaper, lighter and overall better option?

But before you throw that old OS46 away, try it with a good 12x4 wood prop (JFX, XOAR, Volk, etc). You might be surprised how much better it runs than with the 13x4. And if you're using the stock OS muffler, throw it away and fit a Tower or GMS47 three-piece unit. You'll gain up to 800RPMs straight away and that makes a *huge* difference in pull-out when hovering.

Daniel Z

yep, I agree, tower mufler, 20% nitro and 12,25x3,75 APC makes my 2,1kg plane climb very nice with my old 46FX

WMB

My Feedback: (1)

The 11.5x4 APC has mucho thrust as well.

doublesixes

XJet,
Before committing to buying a new engine, I will explore your suggestions, a 12X4, although the big cowl in my Yak would prefer a 13 inch or bigger prop, and perhaps replacing the muffler with the GMS from Tower. Thanks for the feedback!

rzarikian

Yes first try a new prop (apc 12.25x3.72 or a 12x4 or 13x3 WOOD) If pull-out is still lame and you want something a bit more powerful then a saito 72 or a OS 55ax would suffice. The saito 82 is a great choice since it shares the same weight and mounting dimensions with the 72 but has 20% more power so it has a better power to weight ratio. just be careful not to overspeed your plane or you will rip your wings, use full throttle only when vertical. oh and for the props: for the saito 72/82: apc 14x4W and for the 55ax mmm... 14x4W ....... naa it wouldn't turn it, a 13x4 will do, or 14x4 wood.

doublesixes

The OS .55 AX looks appealing since replacing it for the .46 AX should be fairly easy. But the 70FL has the advantage in the torque, displacement and more realistic sound departments. Price difference is not an issue. I never had a 4 stroke engine so I'm really tempted to go with the FL 70.
I'm well aware that is not a powerhouse like the Saito 82 or even the OS FS 70 but I can get the FL for a substantial discount.

XJet

Don't get me wrong here... I have four 4-stroke engines and I love the sound but "realistic" they're not.

One of my flying buddies once said "that sounds like a lawn tractor" and he's dead right.

They do have a much nicer sound than your average sport 2-stroke motor (high-performance piped 2-strokes are a whole different kind of music) but they're not realistic at all.

In fact when set up properly with the right muffler and prop and running at an appropriate throttle setting, a 2-stroke can sound a lot more scale than a 4-stroke.

The only 4-strokes that do sound realistic are those big Moki radials now *that*'s realistic!

Check out these YouTube vids for the Moki in action...

http://nz.youtube.com/watch?v=XaQbbf1BNAA

http://nz.youtube.com/watch?v=kYrL-eGEOUY

doublesixes

Unbelievable sounds on those planes. I know the OS FL won't be even close to sounding realistic but it definitely beats your typical 2s small glow engine. All it has to do is being able to haul 2.5 kgs straight up, with no hesitation. Question is: will it do it better and with more authority than the .46 AX?

rzarikian

If your going 4 stroke don't go OS, Saito engines have a better power to weight ratio. (not so important in scale models, but for 3D... ) When it comes to 4strokers for 3D you just can't go wrong with Saito.

4 stroke: SAITO
2 stroke: OS

rzarikian

oh and did I mention how awesome saitos look? gotta love those rocker covers! But really don't get the 70FL, I wont give you the kinda power you are looking for a 82 will give you that power at LESS weight than the FL!

doublesixes

rzarikian,

I really appreciate your suggestions. I believe Saito makes awesome 4s engines. I was never lucky enough to own one but eventually I will
I'm pretty sure OS knows a thing or two about 4 stroke engines. In fact, in the last F3A Championships, the pilots that used fuel, flew OS and YS 4 stroke engines, no Saitos...go figure.
IMHO the FL70 will beat my existing .46 AX hands down. Larger prop, 4s torque, 519 grams w/muffler, basically 30 grams over the .46 and there's no replacement for displacement. And I will pay under $200 for it.

XJet

The OS FL70 would doubtless be a reliable workhorse but it wouldn't be my first (second,or third) choice for 3D applications.

As I mentioned earlier, the air-bleed carby is not well suited to the demands of 3D flying and it might even be a bit down on power compared to what you expect if this post is an indication.

Saving your money for a Saito 82 would be a worthwhile investment and the new TT75FS also looks good (albeit it may also be a bit low on power compared to a good .46 2-stroke).

freeair

i have the Katana freestyle 40 which is a very light model and simular in size to your Yak 54 - 40. this was designed for engines of 40 size 2 stokes or 70 size 4 strokes but i went better and fitted a new O.S. 81 a 4 stroke and i must say its a great combination for both basic pattern and full on 3D stuff.

liquid_TR

Get a saito 82, or if you insist on 70size 4 stroke, at least get the OS 70 SurpassII.. I suggest you stay away from the FL - dead investment..

doublesixes

Looks like the consensus is to stay away from the OS FL 70. That's a pity because I liked the idea of rooting for the disliked, highly criticized FL 70.
Not to mention that I was getting a NIB engine for a lot less than Tower's price.
XJet pointed to an RCU link back from 05 where I found very polarized comments about the virtues or misses the FL 70 had.
I appreciate Ed, (AKA Artisan) opinion, so Ed, if you're out there, what's your take on your FL?
Thanks to all who contributed but it seems I will most likely stay put with the OS .46 AX in light of the overwhelming disapproval regarding the cheap 4 stroke OS.
One thing I'm certain, I will neither get the overpriced Saito nor the under performing (for it's price) FS 70.

Daniel Z

what about a ys63? great engine!

I wouldn`t use a os four stroke too, for me, os 55ax, saito 82 or ys63

doublesixes

The only two engines that I have access to are:

OS .55 AX 2 Stroke
OS 70 FL 4 Stroke

I don't want to spend more than $150 on a substitute for my OS .46 AX

TruBlu02

Well i am going to step in and say that the FL-70 is an awesome motor. I used it in my GP Reactor for awhile and it never gave me a single issue. I flew it hard and it never once hiccuped. I put at least 100 flights on it and never once deadsticked. It will swing a 13x4W APC at 10.5K. Many people who have never used it will knock it based on nothing but their opinion, but it is a simple and reliable engine. Dont be afraid to use the FL-70. It is a great value and an awesome little engine. Here is a vid of my plane with the FL-70.

http://www.youtube.com/watch?v=op5vFG1xyQU

Also the 55AX is hands down my favorite 2 stroke motor on the market. I have two of them and one is used for 3D. I stuck a 12.25x 3.75 prop on my 3D plane and it was ballistic 3D power. I think either of these two motors will be very appropriate for what you are doing.

TimChurch

My Feedback: (1)

Saito 82 will turn a 14 x 6 prop none of the others will, the Ys when running good are fine but it won't spin a 14" prop. Saito is the motor if your thinking 3d it will 3d a 5lb plane well.

Mojo for 40 size 3d planes

doublesixes

Trublu, that's a great looking plane you got over there and the FL-70 seems to be a good match. Can it pull out of a hover convincingly?
My Yak is somewhat smaller and lighter than your Reactor so I have no doubts that if this little 4 stroke engine does it for you, it will more than suffice for my needs. Good flying too (nice inverted pass!)

airraptor

My Feedback: (66)

LOl you come here asking for advice and the guys give it to you but still want to buy the OS 70FL lol that 70 turning a 13x4w at only 10,500 my saito 56 will do that.

a saito 82 or If you have to stay with OS then get the 55 and a tower muffler for it ( 15.00 dollars)

IF it was me though i would go with saito or a JETT .76 turning a 14x4w at 14,000 and its the same weight as the OS 55

TruBlu02

Thanks for the compliment. There has been alot of negative commnets in here and it seems like no one answered your original question which is why I posted. I have used both engines you asked about and I love both of them. I know the FL-70 is not the most powerful engine on the market but it is a solid and reliable motor that gave me not a single problem. My plane weighs a little over 6lbs and it would hover but really had no pullout. But since your plane is lighter I think it would be just fine for that purpose. I eventualy went with a Saito 82 since it was a litlte more suited power wise for the weight of my plane. I have no brand predjudice when it comes to engines unlike some of the other posters and I advise you make the decision based one experices from people who have used these engines. If it were me though I would slap a 55AX and APC 12x4 Prop on that little plane of yours and watch out! Good luck with your decision I hope my input helped some.

doublesixes

Airraptor.
Although I appreciate all the input received after my question, I was not convinced one way or another whether the FL-70 or the OS .55 AX are the right replacement for my .46 AX.
Trublu is the only one that substantiated his advice with a video. Based on that video, it's hard to extrapolate if that engine will suit my Yak for 3D flight, nonetheless, it's the best reference I got from this thread so far.
If I wanted to spend good cash on this project, I would have gone electric altogether and not messed with Saitos, OS, YS. I just happened to own an OS 46 AX and I thought it would've been OK for this bird, which is but just for sport flying.
I can get NIB ONLY an FL-70 or an 55AX for real cheap. Saitos, YS, Moki or whatever are out of the question. so is the preferred electric option.

airraptor

My Feedback: (66)

if the 70 FL and 55 are your only two choices then go with the 55 it will have more power than the 70. also get the tower muffler for for a 500-700 rpm gain over the stock muffler and its only 15.00 dollars from tower hobbies.

Saitos have always had more power than OS four stroke up to 1,500 rpm in the smaller engines 1,000 in the mid sized ones and around 500-600 more in the largest ones. Plus the Saito's are lighter. I have always liked OS but when i want the most power there is only one engine to buy in four strokes.

like i said i like OS and have one of the small .30 fours with some compression work and porting have it turning a APC 9x6 at 16,000 more power than a OS 25 FX and the new 35AX with everything stock.