[Gary Maker]

I am sincerely asking this question because I would like to have some input on this. I would like an honest discussion and reasoning on this.

Its ok to like power. And I have honestly heard some people say "Too much power is just right!" I've seen people put much higher than recommended engines on planes and would honestly like to know - How much power is too much?

Heres just a couple of examples:

Goldberg Extra 300. Recommended engines are .60 two stroke to 1.20 4stroke. I have seen these planes with 1.08 to 1.20 2stroke and 1.50 to 1.80 4strokes. Twice the recommended power in some instances.

For more modern planes and engines theres the new Wild Hare Edge 540. This is a 28% scale plane weighing 17 Lb . I have heard its designed for engines like the G62, ZDZ 50, DA50 etc. Most of us have heard of the powerful new MVVS 58, 9HP, with 48lbs of thrust swinging a 26 X10 prop. These engines are being purchased for this plane with all most twice the recommended HP.

Is too much power just right for these planes? Where do you draw the line on how much over powered you can go these days! Is safety an issue here?

This is not meant to be a criticism or to start any heated argument. I would really like to know how you determine how much power is reasonable!

Thanks in advance for your comments.

[Nuker]

Wow you're gonna get thousands of opinions

So here's mine

First off I look at the airframe, what size engine can it support. If I'm going bigger, what re-enforcements would I need to do.

There is also magnitude. In theory a Sig Fazer, or equiv, needs a .40 engine but most guys at our field will have a .46FX with a 12.25 x 3.75 prop. So they are actually overpowering their plane.

For most of my planes I prefer to select the suggested engine, though I tend to move towards the upper end of the scale that they provide.

For one plane I'm looking to vastly overpower and am looking at what upgrades I'll need.

What's important is that just because you have all that more power, doesn't mean it will be used all the time or at all. There is something of a comfort to know that you can rely on extra power to get you out of trouble if you need it.

Some flyers like to fly off the prop. Kinda thing where the prop stands still and the plane rotates. Others like flying off the wing and controlling the plane that way. Strangely enough, it's throttle mgmt that makes more of an impact in this area than the engine size. Of course if the engine is too big you can select either method of flying. If too small, you only have one option

All that being said, it's all about fun and what you want to do.

Bob

ps (I'd put a 1.80 in that new cub of yours )

[Guest]

Firstly I think it largely depends on your skill level. The better you can use the throttle the more you will get away with it.

Secondly, depends on the model. I have heard of guys putting 100 size 4-strokes on 40 size models and going 2 lbs over the recommended weight. Thats just asking for trouble, you now have a model with lots of power that likely doesnt fly as it was intended, and may have some dangerous traits. If you can keep within the weight range and know how to use the throttle then great, but I think its very important to be the correct weight.

I prefer to go light and use a moderately powerful light motor, I feel there is no need to vastly overpower a model, for a nice 3D model about 1.5:1 is plently of power for me.

If propped correctly my most overpowered models are my pattern models (9.5 lbs), with the 140DZ up front and a low pitch prop I can easily exceed 2:1, but we usually run props that only give about 1.3-1.5:1 as they are much quieter. Also the planes are so light for their size that its not uncommon to add weight in windy conditions to get the wing loading up. We shoot for 100 in^2/lb wing loadings, which usually ends up in the low 20's. When flying these models I am only under full power on long vertical climbs, even 45's I only bump the throttle 300-400 rpm.

In pattern all that horsepower causes havoc for new guys, they usually end up all over the place because they have little to no correct use of the throttle. In many cases they would do much better with a smaller engine.

[nony]

...I would be more concerned about the pilot's capability of controlling the power...
-competent pilot - have fun- go knock your socks off
-Inexperienced pilot - where is the bomb shelter??

I'd say anything with a thrust ot weight over 1:1 would qualify as overpowered..

[Gary Maker]

Thanks guys, thats exactly the kind of information I am looking for to help me understand these conceipts.

[ronm]

Gary, at the risk of beating this subject to death again, my opinion is that it depends what you are trying to achieve. I had a .60 size Extra with a 1.20 engine on it last year. More than the recommended power.
Was it too much? Actually, for IMAC basic, I found it to be enough power on calm days. But on a windy day it was not! (in my opinion)
How could that be? The manufacturer advertises it as an unlimited aerobat! Not even close, with the recommended engine.
And it would not even come close to doing the sportsman "Diamond Loop" manuever!
I feel the manufacturers recommendation is just that....a recommendation.
The manufacturers recommend an engine range that is "in thier opinion" safe and proper for most fliers and most types of flying.
You have to get over the fact that you are not within the recommended engine range.
Lucky for us competitors, when you get to the larger competition aerobatic planes, the recommended engine range is a lot more reasonable for the type of flying we do.

I have not heard of a case yet of a warranty issue if using a larger than spec'd engine.
There may be thoughts about safety issues, but there is not a MAAC rule that I know of to restrict engine size to the manufacturers recommendations.
If you are an experienced, responsible pilot, you know how to select the engine necessary for what you want to do. Do what you think is right for you.
If you are not, then most certainly stay within the recommendations!

Ronm

[Guest]

I guess one other thing, there is a vast difference in power in say the "40" size/weight class of engines. Say an OS 50SX vs the 40LA same size and weight of engines (or close enough) but much different in their output!!

I dont think the recommended engine range is as good a way to judge what motor to use as the listed weight of a model. Obviously a 40 is not going to pull a 6.5 lb model all that well.

There is also prop choice, you can really change how an engine pulls a model by simply changing the prop. I tried 15 or so different sizes of props on the 140DZ for my model to see which one I liked the best.

What works at sea level doesnt work in Calgary that well, I often need to change props when going down to fly at sea level. Noise is another consideration to prop selection.

Ok now I am way off topic, anyways there is a lot to think about when trying to properly power a model.

[dougl]

if you have a job and make more than $10;00 an hour...
you can afford a servo to pull the throttle back...

[Andrew Logan]

MORE POWER

[AJCoholic]

Bottom line - there is nothing wrong with having as much power as :

(1) the airframe can safetly handle - that is, the firewall isnt going to come loose, the covering start to peel back, etc... and

(2) the pilot can safety handle - inexperience and an overly powerfull airplane where the pilot may not be able to keep up.

Yes, there is a throttle servo, but unless you can handle the plane you shouldnt be putting a huge (relatively speaking to each airframe) engine on it IMO.


Its a personal thing after that. What do YOU want the plane to do?

I will allways say, I would rather have twice as much as I need, than not enough (in 99% of the cases - there are allways exceptions)