General Engine Question
 

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

RE: General Engine Question
 

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.

RE: General Engine Question
 

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 :D 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

RE: General Engine Question
 

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

RE: General Engine Question
 

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?

RE: General Engine Question
 

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

RE: General Engine Question
 

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

RE: General Engine Question
 

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.

RE: General Engine Question
 

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

RE: General Engine Question
 

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

RE: General Engine Question
 

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.

RE: General Engine Question
 

"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?

RE: General Engine Question
 

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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.

RE: General Engine Question
 

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 :D

RE: General Engine Question
 

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.

RE: General Engine Question
 

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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.

RE: General Engine Question
 

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.

RE: General Engine Question
 

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

RE: General Engine Question
 

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.

RE: General Engine Question
 

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

RE: General Engine Question
 

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.

RE: General Engine Question
 

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:D
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

RE: General Engine Question
 

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

<GGGG>

RE: General Engine Question
 

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.

RE: General Engine Question
 

Foregive me I was sniffing monokote fumes today

RE: General Engine Question
 

BLW....the original poster said he was "new to nitro flying" (nitro flying?). That was MY first clue that he's probably not competing in Top Gun this year.

My guess would be a trainer type model, but.....who knows. If the hobby shop sells 'em a scale P-51 as their first or second model you can rest assured that's what they'll show up with. Been that way for years.

And BLW, you know that the pattern fliers don't just willy-nilly choose a "big one" motor for their airplanes. The actual competition models have firm weight limitations to fit into, and given the size of the pattern planes today...the choice of engines is actually quite limited. Add to that the skill level of a competition flyer, and we can make definite distinctions between a horribly overpowered (and likely overweight) beginner level model in shaky hands, and that 1.60 powered model flown by a pro at the contest.

Just not the same thing.

RE: General Engine Question
 

yeah theres a big thread going in ARF section right now

RE: General Engine Question
 

Ok, I have just read through this discussion, and just have to add my thoughts. In the first place the plane designer engineered the airframe to handle the size of engines noted on the plans,or in the construction manual. This is the prevailing engine that should be considered. It
is possible to reinforce the firewall and fuselage to handle a much larger engine, but will the wings and empennage take the added stress? It would far better to install the 52 which is
recommended, and get back into flying. Choose your second model to use a larger engine. I
really rather not bring up the discussion about liability, but what about a model in an injury accident where the builder installed a larger engine in a model that was not recommended by
the designer? How would insurance investigation not side with the injured party. It is something
to follow the safety codes, but not have engineering asurance that your model is airworthy.
Play it safe, and stay within the design guidelines. Now what I have said here just goes out
the window if you are flying at your own private field, and your kids are the only ones that
may get hurt.

Rich S.

RE: General Engine Question
 

My neighbor just happens to be an insurance adjuster and trust me your insurance company will not side with the injured party
in fact they will do all they can to blame the injured party that's how it works
Now the injured parties lawyer might try it but it's unlikely he will get past the fact that your plane hit his client
and since the power is only suggested or recommended there really is no liability issue with what size engine you use
heck if you put a YS110 FZ on a 1.10 rated plane isn't it overpowered since that motor will out run most 1.40's
the real issue is one of did you CONTROL your aircraft if a safe and responsible manner.
either way is really a non issue if planes hitting people was a problem clubs would not allow spectators even family at the field
after all most are on private property
Now back to the original post he said he's new to nitro not sure if he's new to flying so I say don't over power a 63 inch trainer with a .46 engine can get a beginner into all the trouble he can handle and no amount of power will get him out of trouble since in most cases he will not know what to do to get out anyway the extra power will just make a louder thud when he smacks the ground

RE: General Engine Question
 

race city- I missed that part. I wasn't trying to be argumentive or a know-it-all if it came out that way. I agree about pattern guys who really compete. I was talking about guys like me and those at the club. Just pattern flying for the fun of it. I agree that it isn't the same thing. Some of the best guys I've seen fly pattern did incredible verticals with very little throttle. No engines racing to max revs to get the maneuver done.

RE: General Engine Question
 

Hello Skiman; I like that "a bigger engine will just make a louder noise when it crashes" Maybe that reasoning will make sense to newby's,where a well thought out responce won't.

RE: General Engine Question
 

Well I can still remember my rookie days that ole trainer seemed to be going 200mph and changed directions fast now when I fly it it's seems so slow like a glider
A new flyer isn't even sure what's happening no need to hit the fast forward button
I know this is a costly hobby compared to some others but there will be plenty of time for big engines and fast planes IMO

RE: General Engine Question
 

It only takes one embarrasing, costly, dirt-in-the-transmitter crash to get their attention. All the talk about "more...faster...bigger...better" is forgotten as demolished fragments of the model are loaded into a hefty bag.

When the person is awarded the "Crash of the Year" award at the annual club picnic...it's much easier to talk sense into them. Until that point?

Sit near a sturdy structure, and enjoy the show.

RE: General Engine Question
 

A tad bigger engine will not hurt anything.....and when you need a bigger engine for the next plane....you wil have it. Case closed....maybe! Capt,n

RE: General Engine Question
 

Captain...

That's the rationale that gets them into this dilemna.....

They might fly a 40% model one day. Should they bolt a DA-150 in their trainer?

IMO...use the engine that fits in the mfr recommended size range. A LITTLE out is OK....anything more than a little and they can teach themselves at some other field. I won't help.

RE: General Engine Question
 

LSpliff,
Judging from all the chatter you generated with your question I guess this is a sore subject with some of the members. At the risk of repeating myself, a .75 size engine won't hurt your airplane and will probably fly alright. Make sure the CG is corrected for the heavier engine and don't fly it at sustained full throttle and you'll be fine.
Never mind the flying on the wing, the insurance ramifications, and all the rest of the purest chit-chat. It is your airplane, do whatever you want with it.
Gee, I hope I'm not causing the downfall of the hobby by advising you that it is OK to install a larger engine.
Regards,
doubledee

RE: General Engine Question
 

Wow You're right doubedee... That's one question I'll never ask again! lol But, honestly, I thank everyone for their input. I was away for a bit and just got a chance to check this. When I said new to nitro flying, I meant I only flew the average sized electrics before (nothing elaborate). I flew my friends gas 2-3 times and I figured, hey.. new job.. more pay... let's kick it up a notch. I bought an inexpensive ARF (Corsair - 55" wingspan), not a gas trainer like I probably should have... but what the hell (I'm great at video games! lol). From my experience, I didnt think I was going too crazy. What I was really trying to ask was that the engine I was planning to purchase is about .5 HP and ~5oz. heavier than the specified engine size... Is that too much? I understand the balance issue and I figured that reinforcing the firewall would be a good idea, but also, as was discussed, with the way these are made, will the rest of the plane hold up. I'm not planning on flying this at a constant full throttle... I'm not looking to take it home in a garbage bag :D

RE: General Engine Question
 

Real airplanes, and R/C is real, don't fly like vidio games. Do yourself a favor and buy a good trainer and get a good instructor. A good .46 to .50 would be more than enought power for both the trainer and the Corsair.