I would like to hear of what wild hombres are around here. I mean that you put a 120 on a 40 size or somthing. I have heard of 91's 4st on 40s but... I have only overpowered really 2. One was a GP Big Stick 40 I put an OS 61 fx and was using a 46 mag. Which imo was overpowered. I also had a 61 ST on my extra which I "thougth" was over powered until I heard of some of you folks use much more. Soooo what have you got or did have??..

Who is going to define "overpower"? The general use seems to be if the mfr calls it a .46-.60 size 2C, .70-.91 4c, then displacement beyond those limits is overpowered. But if you want to hover and pull out readily, or you want vertical rolls and snaps, then you power your model accordingly, and it's properly powered. On many models, you can't safely put on a bigger engine without saving weight elsewhere to preserve a decent wing loading; and strengthening the front end. Many times a bigger engine generates stronger vibrations, which also have to be compensated for. If you deal with these concerns appropriately, and you manage your throttle, then 150-200% of the "recommended" displacement is typically workable and often desirable. If on the other hand you want to fly a scale model with scale power, then the mfr's recommendations probably make more sense. If your model shakes itself to pieces, or drops out of the sky when your engine quits, it's overpowered.

I am not really looking for a exact science here, I just thought it would be funny to hear about some guys putting humongus engines on small planes is all. Not a right or wrong thing.

I still don't understand the concept of putting a huge engine on the front of a small plane, ie; Saito 100 in the Funtana 40, then having to add a ton of weight to the tail so it balances. All your doing is creating a plane that can rocket in the the vertical but falls like rock because you increased the wing loading, I don't get it.

Does an O.S. 61 sf-P in a Hots count?

with today powerplants being on the lighter side of town sometimes it doesn't seem like I am overpowering my birds. + the birds have more lighten holes in them so even they are lighter so all in all.

all of my older heavier fun fly birds received satio/OS-91
u can do received a RCS 1.4
great planes cap 232 satio 91
15 sized strike tt-32

any 46 planes needs a 91-4 stroke use to be my rule of thumb


Lets not even bring up any Dave Patrick model as he would say i am overpowered a FX 46 on 30% nitro

How about:

Jett .50 on 40 sized Kyosho Spitfire
Super Tiger .90 on a World Models Chipmunk
O.S. .25FX on a Ace Baby Ultimate Bipe
O.S. .91 FX on a Kyosho .40 Sized Gee Bee Z
Jett .90 on the Hangar 9 60 Sized Corsair (Haven't flow this yet)

All fly extremely well (Except the Corsair (Don't know yet)), without any additional weight needed.

I had a GP Corsair ARF a while back, and I put an OS 61 fx on it and I still needed 1lb of weight in the nose. I know that sounds a lot but I wished I had put a 91 4stroke on it. It would have flown better and taken off better. This was even a 40, if I had put a 40 size engine on it it would have never gotten off of the ground unless I had a 100yd runway. It flew decent with the 61 but a 91 4stk would have made it better.

I have a 40 size ultrastick with an os 91 fx. same weight as tt 61 pro with both equiped with pitts mufflers. with cg at aft limit it still lands like a stick.

I have a TT61 in my Global 40 Ultimate and I had a Tiger Shark 75 in my Kyosho 40 Cap 232. If you go by the manufacturers recomended engine they are/were over powered but I thought they were perfect choices for the airframe.

GP 40 Cap 232 will have a GMS .76- with servos move aft- antisipate weight at 5 lbs. I love to fly heavy wing loaded planes as they land faster and allow me to fly them under power to runway. And I love flying the Gee Bees in cross wind conditions, but thats just me!

The trick to intelligent overpowering is to add useful weight and power to the airplane. I see many cases here of RCU of people adding a huge engine to a plane and maybe only adding speed or climb, but losing agility, which is something I look for in most airplanes.

First, you need to match the power to the type plane. Next, you need to insure you just don't add more power, but in addition, add more weight that nearly negates your power.

In a fun fly plane you want extra power to pull up from a fall out of a hover or some maneuver near the ground. You also don't want to limit your plane by also adding useless weight. As an example, a Goldberg Extreme 330 usualy builds tail heavy with a .46. The mean weight for a .46 is about 17 ounces (16.5-17.7 from my engines). If I need 3-4 ounces nose weight, I can add an engine that weighs that much more without changing anything. It turns out the Saito .91 weighs 20.5 ounces, only 3-3.5 ounces more than a typical .46! You need to trim the nose a little, but the big Saito .91 can be shoehorned in, giving you tons of extra power without requiring any tail weight to compensate. No other 4-stroke .91 can do this.

The Burrito, on the other hand, has its moments chosen for a .46 and would be nose heavy with anything larger. It is also lighter and flys very well with the smaller 2-stroke.

My buddy and I have a scale Northrop A-17A 30's era dive bomber. It was the predesessor of the SBD Dauntless. (At the time Northrop was a division of Douglas.) It is a radial engine plane with, naturally, a short nose. Ours was built by my friend for me and was scaled up from smaller plans to a 68 inch span. During construction, we found that a normal .61 would require several ounces nose weight to compensate. It just happened that I had a Magnum 1.08 in a Joss Stick that I used for testing and running in .91-1.20 size engines. We checked it and the plane required no additional lead. Further, the prop the big Mag could turn, a 15-8, would easily clear the radial cowl. It has been a great flying scale plane, very aerobatic (it flat spins) and the extra weight and power hasn't hurt at all.

As for using a .61 in a .46 size plane, this is the worst engine change there is, in my opinion. Most .61 2-strokes weigh over 25 ounces compared to the 17 ounce .46, by my weights. That is just over a half pound added. A .50-.53 with a Tower muffler or tuned muffler like the Ultra Thrust will more than likely give you more total performance.

Furthermore, in my opinion, the .61 is heading the way of the .40-a useless engine that has very little future. Why buy a .61 when there are .75s and .91s in the same case, weighing the same, but producing much more power. Ball bearing .40s hung on for a while, but do you see many now? Why buy one when for $10 more you can get a .46 with more power and the same weight. I think the .61 is headed that way.

I just noticed that Tiger Shark is listing (but not in stock) a .56 in the .40-size case. It's a punched out .52. 16-17 ounces of .61 killer. How long before other manufacturers catch on. And if you don't think the .40s are going, notice the Irvine .39 and the Tiger Shark .39. Basically the same displacement as a .40, but built in a .32 case at 12 ounces. With these engines, we are talking power-to-weight ratio in a fun fly plane. Now go power your .28-.32 size plane with a .39 and your .46 plane with a .56. Now you are talking serious overpower without a weight penalty.

rc_sport-RCU ,

I guess you do not have a Funtana with a Saito 100 in it as I added absolutely ZERO weight in the tail to balance. I just moved my battery behind the wing bolt and all-up weight is right at 6 lbs. It elevators perfectly inverted and up-right with hardly any wing rock. IMOP, the 100 is perfect!

holy cow!! that funtana must scream then. Have any pics?

I hear its a real thrill to fly a SIG Small Wonder with an OS32 or something like that ... you might see the engine pulling the tank away. Hehehee ...

Hello I have a Great planes cessna 182 arf with a saito .91 under the cowl. I should mention it's a 40 size arf, strange thing to see it go vertical on take off . I often power back to just above idle and cruise the field.

I mounted and flew a Magnum 120 two stroke on a Hobbistar 60. I relocated the battery near the rear in order for the plane to CG right. I made a trap door for battery access for final positioning. The plane flew like a rock though, it was just too much weight for the wing loading. The front landing gear was to weak for the weight (should of went tail dragger), and the LARGE tires were needed for prop clearance.... hee hee

Yup, it had unlimited vertical.
Dennis

Several 40 size World Models P-51's highly Mod'd for racing with YS 91's, 120's and 140's. A screaming YS 140 on High Nitro (50%) and a clipped wing 40 size P-51. Gotta love them!!! My 91's and 120's are actually faster though!!!

I put a OS .46 FX in a Sig Wonder. I spent a lot of time "Wondering" where it went. Seriously you had to be quick on the sticks to keep that little thing in sight. Haulin' A** was an understatement. Funny thing was it did not meet its demise in the air or result there of. Burned up in a car fire.

Jett 90 on a Ultra Stick 40

now were talkin, he he. How did it balance out?

Not to bad. added a little weight in the tail. Acceleration on the Vertical take offs is decent. I guess we should put it on a diferent plane.

TF P-51 (60 size) and YS-120

I have a Jett-50 on a 3.5 lb. Scatcat (Quickee type) [X(]

Also, someone in the Speed forum put an OPS-60/61? in a .10 sized Shrike-

I'm putting a G38 on a H9 taylorcraft

My Saito 100 powered Funtana .40 weighs about 3 oz more than the rest and flies/lands/harriers/balances extremely well. That's about 5% more weight for about 40% or more extra power. Good tradeoff if you ask me, especially on 714 square inces of wing area.