Hi all. I'm fairly new to nitro flying and I have a question. I purchased a plane that requires a 2 cycle 40-52, or 4 cycle 52-60 engine. If I were looking into a 2c .75 engine, am I serverely overpowering it? If I am, how high could I go before the power/weight would hinder the model?

Thanks for the help

Most 75's are the same weight and exterior size as the 60 type engines.

It depends on your plane but it should be OK.

If you are new, it wouldn't be a good idea to have a over powered plane to learn to fly on.

ok... I used to fly a little electric but that was a little while back. I was just getting back into where I left off. I wanted to get an engine that I can have fun with and not get bored of right away too. Instructions are just suggestions In all, would the 75 be too much for specs? I dont want to see the engine taking off with the cowl and leaving the plane behind lol

To me, an underpowered plane is more dangerous than an overpowered plane. At least if you have too much, you can throttle back.

If you can fit the engine in the front of the plane it will be OK.

Be sure and balance the plane. You may need some lead in the tail or move a servo to the rear or the battery?

That was the selling line! Thanks all for your help. I'll make sure I balance it out as you said as well.

Thanks again

Yeh, what he said. One basic rule is to go with the higher of the recommended choices. Nothing worse than having an underpowered plane.

On this one here, that can happen anyways. Al my fleet is overpowered. Just run a bead of epoxy on the firewall corners inside and out for added strength.

I have seen engines go one way and planes the other.

Go for that 75 (tower 75??) Most beginners have to weak engines and often crashes trying to get in the air. Use full power to leave the ground and gain some altitude, then trottle back

My 2 cents worth. Agreed, it is better to have too much power than too little power as you can always throttle back. You can't throttle up any more than full throttle so not enough power can get you in trouble. I kind of use +33% as a rule of thumb. If manufacturer recommends a .60 size I mount a .90 size engine. In your case a .52 is recommended, so a .75 will be fine.

Regards,
doubledee

Hello; I see what is happening here; a person asks for advice, when the advice comes in, the asker acts on only the advice he/she wants to hear. The designers of the plane must have some knowledge about what engine works in their plane.

"You can always throttle back" would be a valid statement provided the flyer would think to do this. Most won't, and in fact the throttle stick is typically one of the least used of all the controls...it's a toss up between it and the rudder as to which is used least. Many flyers could remove the throttle servo entirely and not notice much difference. Particularly with ARF models of dubious construction quality, it will be a short time before the tail or wing parts company with the model during a completely disoriented full power dive. A margin of reserve is always a welcome attribute in a model, but particularly when learning to fly...horsepower is not a replacement for developing flying skill, and is just as apt to get you into trouble as it is to help you get out. I might wonder why certain individuals seem to need to get out of trouble so often! Remember now...this is most likely a trainer we're dealing with, not the latest, greatest 3D plane.

Given that most engines make rather good power for their displacement these days...there's nothing wrong with using an engine in the recommended range. But that's not going to happen is it?

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I once designed a model (The Hail Razor) that was basically a .40 - .53 two-stroke sized model, but with provisions for moving the battery pack behind the trailing edge of the wing for the times that I wanted to power it up with an old pattern .60 (Super Tigre G60 ABC/ring). I even had an external hatch behind the wing's trailing edge, making moving the battery rearward a piece of cake.

Now, this model was a tad heavy for a .40 (6.1 lbs.), but flew well (spirited) with an Enya .45CX. The conventional landing gear wasn't a problem during takeoff (this was a low wing model, by the way). People remarked at how fast the model flew with the .45CX.

I was using an Edson Universal Adjustable Engine Mount, which meant that the jaws could be reset to accept a larger or small engine. I got tired of flying it with the .45CX and wondered how it would fly with the ST G60.

After all, the .45CX was a then new high powered/high tech engine and it really roared. How would it stand up to a Seventies design pattern engine?

After all was mounted and changed over, we went to the flying field. Fueled it up, range checked it with engine off and engine running. All was okay. I went to take off and that is when I got my first surprise. The torque of this engine raised the right front wheel off the ground so much that the model swung around in a small left turn and headed back toward the pits no matter how much right rudder I held. I tried this four or five times with varying amounts of throttle. If I had enough throttle to move the model toward a somewhat reasonalble takeoff speed, the model swerved uncontrollably toward the left. No takeoff. We flew from a grass field, by the way.

I thought about it for a while and then decided to go for a banzai takeoff. Full throttle and full up elevator. I knew I had enough power to pull it off and it worked. The model didn't even roll. It just jumped into the air and went straight up (after I let go of the up elevator).

One of our club members, who was a former airline pilot and was then working for Flight Safety who trained and certified airline pilots in their simulator, came over to me and said, "Ed, that plane doesn't takeoff, it explodes off the ground". He was right.

So, how did it fly with the G60? Well, it was a lot louder (open front Mac's muffler - you could do that then) and it was a tad faster, but it had unlimited vertical with the .45CX and, frankly, it didn't handle as well with the tiny bit of extra weight (about 4.5 Ozs.). I flew it a few times that way because the guys were getting a kick out of it, then I refitted it with the Enya .45CX and had a ball.

Sometimes bigger doesn't get you what you thought it would.

My son grafted a 1.08 onto his old beaten up 40 trainer (he moved the engine back about 3" though) and it handled beautifully. Takeoffs were dead easy although he opened the throttle fairly slowly and by the time he got to about 1/3 throttle it was in the air . Landings were just as slow and easy as with the original small engine except you had to do a 3 point or the prop would touch the ground

Lorne,


Being a beginning modeler, you should learn some basics.

Using a larger engine will make you plane heavier.
It is not only the engine that weighs more, but also the larger fuel tank and the counter-balancing in the tail (which can be averted if Brian's approach is used...).

Your engine of choice should be the same weight as the intended engine.
More power? No problem. You can always throttle back (unless Curt is right...).

More size and weight; I wouldn't recommend it. It is just adding to your problems.

Models are always overpowered, with their basic engine size even.

Propped ideally, a .40 size trainer, with a .40 engine, would put itself up vertically.
Even with a regular 10x6 prop, it would climb at 45 degrees...
Can you imagine a Cessna 152 doing that?

To learn to fly your model on the wing, as it was designed to fly; not hang it from the prop, just get the recommended size engine.

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I have seen and experienced what you are citing too, Downunder. It depends upon the model. My Hail Razor was very short coupled, much more so than a normal sport model. The length of the fuselage of that model was limited in length because I only had 36" long balsa sheeting available and I didn't feel like making a scarf joint in order to lengthen the sides. That will teach me. <G>

My point is that it is easy to be surprised during those first few flights, if you haven't taken everything into consideration. Of course, that is the fun of rolling your own model designs.

A friend of mine built a Great Planes Trainer 60 (symmetrical airfoil) and mounted a piped OS 1.08 on the nose. What an astounding hotrod, without the bad takeoff habit my Hail Razor possessed. The Hail Razor was a very good flying model and possessed a 23% thick airfoil. It would snaproll, but only with power applied. Landings were very nose high, if you so desired. I wish I had a picture of it to post here.

If you are learning to fly you may never learn to properly a model on the wing with an overpowered plane. I have seen too many experienced modelers who can't keep their plane in the air when the engine cannot provide the power. Typically they add too much up elevator and stall, or put the plane in thinking it is unplayable.

One of my planes is a slightly overweight Kadet Senior with a K&B .40. On a hot day it struggles to get in the air. No problem just let it get some speed on the ground before giving it up elevator, then do so slowly. When the wheels get off the ground you relax the elevator, then maybe some down elevator to make the plane fly straight and level. Let the plane gain some speed and then relax on the down elevator. It will then slowly climb. When it is almost tree top level it will start climbing normally. Out of the air heated by the ground I guess.

Edit: Changed "will never learn" to "may never learn" spelling.

LSpliff,

Installing a bigger engine is your prerogative, after all, it is your airplane. I once put a OS120FS on a 60 size U CAN DO. WOW!! I had to put bigger diameter wheels on it to get the prop to clear, but, oh how that airplane would perform.

Power management is a learned skill and should be taught and practiced no matter what size the engine. I personally like extra power (30%), and, yes, airplanes should be flown on the wing and not the engine. One of the reasons I don't fly foamies.

There is a point where the weight of the engine overrides the extra power gain, but up to that point it won't hurt to add extra horsepower. Putting a .75 on your airplane isn't going to hurt it. Just make sure it is balanced.

After all, have some fun.

Regards,
doubledee

I didn't say he couldn't or shouldn't. Just that during the training phase oversized engines can (not allways) lead to sloppy habits. I love overpowerd planes, but love the Kadet also.

Sport pilot,

I didn't mean to reply to your comments directly, pushed the wrong button, I quess. What you say is true and some days I like flying a nice, slow, easy to fly airplane. I relaxes me and makes the problems of the world go away for awhile.

Regards,
doubledee

Daris right,

The manufacturer has a recommended size. He also gives a little leeway but the size is what is recommended.

Ifwhat most of the guys is true then wy just stop at a 75? Why not use a 90, 108, or even a 160??

Flying an overpowered airplane is not the way to learn. I think too many guys forgot what it was like learning. Flying a heavy bullet ain't the way.

The power specs also have to do with the airframe strengh I know I'll get jumped on and I over power to a degree
but If I snap off a wing I don't go saying the plane is a POS since it may very well have stayed together if it was power as recommended sometimes speed kills
throttle control yeah right like that will happen
also weight needs to be considered if the bigger engine weighs more the cg may need more tail weight which goes toward killing the wingloading and effects how the plane flys
I'm not saying don't overpower but it seems that flying on the wing is becoming a lost art

Ski....you can hardly get 'em to BUILD a wing, and now you want them to FLY on it too?

<GGGG>

He never said what kind of plane he wanted to put the .75 on. I've been watching some really good pattern guys fly and overpowering a pattern plane is a good thing for nice verticals and power on demand. Of course, these are guys smoothly working the throttle when they need it. My current pattern plane isn't overpowered and I can see where a bigger engine sure would make things better.

Foregive me I was sniffing monokote fumes today