Why the heavy engine?
 

Hey,
One thing I always hear about, especially on RCU, is people putting engines way too big in planes. Why is that?
I don't meen to shoot at people here, but I never really figured out why they do it. I can obviously understand why you would do it if the performance is marginal, but there are alot of guys throwing larger heavier engines into planes that don't need them.
The plane flies worse, (which then comes out as 'the plane flies crap......tipstalls on landing......not worth the money.....blah blah blah.') I really see this in the 2 meter or 25% scale end of the market, where people put gas engines in there, with little power advantage, and huge weight penalty.
Usually, the power advantage is good, but not needed, and the plane will fly absolutely pathetic when it is so overweight.
A prime example of this comes with alot of questions people asked me, regarding engine choice for the Funtana. I gave them my selection of favourites, OS's and YS's, and then they e-mail back asking about putting gas engines in. Someone even asked about a 3W 70!!! Look at the Funtana.....Its matchsticks, and the reason it flies so well, is because of the very light wing loading it has. The designer has obviously gone out of his way in trying to make this as light as possible, to give you the best flight performance, but then you put it over 5 kgs with a gas engine. Thats over half a kilo more weight, which WILL MAKE IT FLY WORSE. I don't mind if you prefer gas, but a 3W 70????? After you destroy the airframe, you'll find a good handling plane, with tons of power in a 3W 24.
At the end of the day, it is up to you, and I am not trying to tell you that I am right, and you are wrong, but I still want to know why power is being put infront of weight?
Thanks,
Robert. :D

Why the heavy engine?
 

They could be flying at altitude and need the power.

Why the heavy engine?
 

When I was learning how to 3D (about 1 year ago) I did exactly the same ... I used to put HUGE engines in very small planes !!! ... haha, my last "project" was to put a Webra 120 in a US 40 (BTW didn't come out of an inverted flat-spin) !!!!!

The main reason for putting huge engines in small planes is because I though I'd be able to hover and bail-out faster and better, but FALSE!!! ... unfortunately, by the comments in these forums, a bunch of people apparently think the same way !!!

I totally agree with you and (without bashing nor pointing fingers at anyone) I think over-powering (not precisely talking about using a 46 for a 40 sized airplane but more like using a 120 in a 40) airplanes is the dumbest thing one can do! ... that's of course if you're looking for 3D performance (which is the main reason why people over-power their planes) ... or has anyone ever heard of an Avistar or any other 40 sized trainer with a Saito 100 in it ???? .... NO !

I have also read things such as "but the XXX is only 2 oz heavier than the YYY" ... that is true and while 2 oz will probably not load the wings that much and assuming you manage to balance the plane w/o adding lead in the tail, the torque produced by XXX will definitely make your plane fly like crap !

Why the heavy engine?
 

Wing loading!
Wing loading!
Wing loading!

Oh yeah,
Wing loading!!!!!!!!!!

keep it light and it will fly better no matter what motor you put in it.

Why the heavy engine?
 

yep, i often wonder the same thing myself

Why the heavy engine?
 

I saw the Jason Shulman video where he recommends 2:1 power to weight for 3D. I guess the trick is getting a plane that is made for it?(not too many) If you put the recommended motors in allot of 3D planes they don't perform. This is why you might see it more in the 25% planes. At 15 or 16 lbs. it's hard to get a glow engine that will allow you to rocket out of hover when you go low and get in trouble but when you get a gas motor that will do it you are too heavy! I plead guilty. Right now I'm working on a Lanier Edge 540T 1.20 with a Moki 2.10 :D .

Why the heavy engine?
 

Jason also flys 40%ers, where 1-2 lb isnt as critical as it is in the 1/4 and below planes

Why the heavy engine?
 

Most of the the 3D maneuvers I can think of dont require a lot of power (Hovering and TR'ing being the exceptions.)

Walls, blenders, terminators, elevators, HA rolls, harriers etc dont usually require full output from the motor.

Why the heavy engine?
 

True but 2:1 is still ideal for 3d! And you guys are right, when it gets too heavy the wing loading and your performance suffers.

Why the heavy engine?
 

I would give anything to be able to put a smaller engine on a plane i.e. better wing loading. You people at sea level need to come here and fly at 5000ft. Your planes would be dogs here! No torque rolls, No vertical, No knife edges, just boring scale like flying!

Why the heavy engine?
 

I have argured this point till my fingers hurt,but they don't seem to listen.The best part is they they'll swear how good their 25% plane flies with the 50cc"Gasser".I give up trying to convince them.I've been there and I know better.I could go on and on,(and have)Oh well to each his own.
Mike

Why the heavy engine?
 

Mike,

Thats hilarious! Sounds like we know the same people.

now I'm confused.
 

It sounds like you guys are saying that it's overkill to put a 50 cc gas engine on a 1/4 scale plane in order to obtain 3d performance. A case in point is the GP PW extra. Many say this plane requires a 50 cc engine to have evough authority for 3d flying. It sounds like you guys are saying this is ridiculous.
I just bought this plane and haven't decided on an engine yet. I want power for 3d performance. However, I don't want to spend more than is necessary for unneeded power.
Is 2:1 power to weight truly unnecessary?
Dave

Monster Engine... Cricket Fuselage
 

That's how I'm described by my local club. "That's like bringing sand to the beach!" one guy said. Here is the truth. I look at the plane with the recommended engine (if an ARF) or the plans for the illustrated engine (if a kit). I find out what the engine(s) weigh and try to find the most power for that weight. If there is, for example,a plan showing a 61 FX on the nose and the battery in the gear block area. It may also show a 91 FS with the battery in the canopy. I look at the weight of the 91 FS and feel justified in any engine of similar weight. True life example. I bought a Goldberg Ultimate ARF and a 91 FX. Many people praised me for buying a "reasonable" engine, "Frank is growing up guys...". It flew like crap. I looked at the plans of the kit version and it showed a YS 120. For me this gave me "permission" to fly a 31 to 33 ounce engine. The Webra 120 was right in there and even fit into the supplied mount. I got the "sand to the beach" speach again and all but laughed at. It was perfect. Nose high stuff and all. It landed at a walk. It also took off in 5 feet or less in a head wind! My Ultimate flew circles around these guys for 2 years before I sold it. I sold it to a teenager looking for a good aerobat. I sold the plane, radio gear, and engine for $300 (I like the guy). A "friend" of mine tried to talk him out of it. He said it was too heavy to fly well, and (get this) NOT WORTH IT! I guess he forgot that me and my Ultimate flew circles around him and his 1/4 scale Cap all season. I do believe there is a point where power gets rediculous. Personally, I don't get turbine powered model helis. I do believe thet lighter flies better, but don't condemn until you try. I also got a laugh when I bought a Rossi 53 for a 4 pound fun fly. Now they are showing up all over. If I bought a 17 pound Extra, I'd be hard pressed not to put a Brison 2.4 or BME 50 in it. That seems just about right. After all, let's not forget that many of the T.O.C. planes wing loading is in the low 30's. For some reason most modelers are not happy with plane above 25.

This is just my opinion. Maybe I'm out in left field, but If the plane balances without an huge amount of lead, and flies well... What else is there?

:confused:

Why the heavy engine?
 

Like in the original post, I don't mind if the plane was not performing well, but I never get why sometimes, people put an absurdly big engine in there, that has more un-needed power, and just weight,

Why the heavy engine?
 

I agree, but my point was that it's weight and not power to blame. Why, other than money, would anyone put a Zenoah GT 80 on a plane when the DA 100 or BME 102 is out there? Why would anyone put an OS 120 FS in a plane when there is a Webra 120? (Please do not do the 2 stroke versus 4 stroke thing.) We are talking weight and power here. Put all the power you can, just keep the weight close. This years absurd notions are the future's comon sense. Why in the heck would you build a fuselage when a profile works just fine? Why would anyone have a 40 size plane when a 1/2 A flies well? Why would anyone buy a 4 stroke when the 2 strokes run so well? All are answered the same... Different strokes my friend.