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-   -   seaplane / weedeater help... (http://www.rcuniverse.com/forum/scratch-building-aircraft-design-3d-cad-174/11295584-seaplane-weedeater-help.html)

joshrc110 11-12-2012 07:39 PM

seaplane / weedeater help...
 
1 Attachment(s)
ok guys iv just got a nice neptune seaplane 60" nice fuse build and i love the plane all but where and how the motor is mounted... i also want to mount a 26cc weedeater engine iv been working on.
so my questions are
www.valuehobby.com/60in-neptune-seaplane-arf-almost-ready-to-fly.html

is 60"" enough to use the 26cc engine? it did use the K&B .40 nitro engine
also i want to mount the engine on the front and ad landing gear so it will no longer see water.

ill include pics not the greatest but pics none the less...

any help is always appreciated

foodstick 11-12-2012 08:00 PM

RE: seaplane / weedeater help...
 
I don't think it will work ... I have put 25cc on some planes before, but thats not much wing to be flying off water, with that big motor on board. Also you will probably run a 16-8 two blade prop, or a 15 inch three blade? Clearance will be an issue.

I'd love to see you make it work, but its dicey at best...

joshrc110 11-12-2012 08:06 PM

RE: seaplane / weedeater help...
 
it will no longer be a seaplane im putting landing gear on it.... still think it wont work?

longdan 11-12-2012 08:07 PM

RE: seaplane / weedeater help...
 
Given that a 40 engine is 6.5 cc, I think the weedeater engine is a massive overkill. I wouldn't put more than a 61 (10cc) on something like that, but that's just me.
I know that glow engines are less powerful than gas engines of the same displacement, but not by a factor of 4, which is about how much you are increasing the engine size by.
I'd look for a bigger plane to mount that bad boy in.

joshrc110 11-12-2012 08:16 PM

RE: seaplane / weedeater help...
 
well with the 40 it is slow and moves slow i want the weedater engine on there to turn the plane into more of a 3d plane


haikt 11-12-2012 08:35 PM

RE: seaplane / weedeater help...
 
You don't have enough wing area for an engine that size. That engine should go with a wing span of 73+.
Nitro engines are more powerfull then gas engines and are lot lighter.
You can try it but very likely will end with disaster.

joshrc110 11-12-2012 08:37 PM

RE: seaplane / weedeater help...
 
well iv been looking online and 60" seems to be good for 26cc
??

foodstick 11-12-2012 08:44 PM

RE: seaplane / weedeater help...
 
I think the smallest airplanes I have flown successfully with a 25 cc conversion was an ugly stick, I can't recall the numbers I sort of used to use as a rule of thumb.. but I think you need a minimum of 900 square inches...

I think the ugly stick was about that many square inches, and weighed around 8 pounds, I had to chop the nose of the plane 4 inches and mount the radio and battery under the stabilizer to balance without using lead.

joshrc110 11-12-2012 08:46 PM

RE: seaplane / weedeater help...
 
www.dragtimes.com/video-viewer.php
the plane in this video i believe in 1400mm witch is not to much bigger then my seaplane and the thing flys great?

joshrc110 11-12-2012 08:48 PM

RE: seaplane / weedeater help...
 
i was thinking of making small attachable lead plates on the back so it will alow me to balance for what conditions im in?

joshrc110 11-12-2012 08:54 PM

RE: seaplane / weedeater help...
 
and if you look on this site it says 63in = 26cc to 30cc engine http://www.tradekey.com/product-free...cc3408912.html

joshrc110 11-12-2012 09:22 PM

RE: seaplane / weedeater help...
 
i also think i need to make my ailerons bigger? how much nose would i need to chop off to mount this engine

joshrc110 11-12-2012 09:40 PM

RE: seaplane / weedeater help...
 
what if i make my wings a bit bigger would i need to modify the fuse?

joshrc110 11-13-2012 03:26 AM

RE: seaplane / weedeater help...
 
any ideas ? i want to make this work!

smithcreek 11-13-2012 05:38 AM

RE: seaplane / weedeater help...
 
sarcastic remark removed. Please, continue, and don't forget to video.

GerKonig 11-13-2012 06:35 AM

RE: seaplane / weedeater help...
 

Quote:

ORIGINAL: joshrc110

well iv been looking online and 60'' seems to be good for 26cc
??

Everybody advised against it. You have your mind made up. Why ask? You would be adding a lot more weight that is needed to that model. You do not have 3D control surfaces on it, but, do not listen to us.

You will have to redesign entirely the fuse, chopping off all the nose area, because of the weight of the gas power plant, then you will have to reinforce all the fuse because of the vibrations of the gas power plant. You will end up with a really, really heavy 60" model...

Idea: you could get a model designed for you power plant, like a giant Sweet Stick... and be at the field in one week, having fun...

If you do this, do not forget to video the event, and share.

Good luck!

Gerry

pmerritt 11-13-2012 06:44 AM

RE: seaplane / weedeater help...
 
Put it all together Josh, fly the hell out of it.  Make sure you have someone at the field with a video camera.  We love exciting RC Crashes!

bogbeagle 11-13-2012 07:15 AM

RE: seaplane / weedeater help...
 
IMO, it'll fly like a plank.

GerKonig 11-13-2012 07:26 AM

RE: seaplane / weedeater help...
 

Quote:

ORIGINAL: bogbeagle

IMO, it'll fly like a plank.
And glide like a brick:-) But, hey, the Space Shuttle also glided like a brick, and always landed successfully...

Gerry

do335a 11-13-2012 07:27 AM

RE: seaplane / weedeater help...
 
1 Attachment(s)
Where to start to explain why this is not a good idea?

The plane does not have the overall size or structure to mouint a massive, heavy, magneto ignition 26cc weed whacker enigne.

A website suggesting that a 60" wingspan plane is OK for a 26cc weed whacker engine is of no value. Take a look at something like a 110" span motor glider. You'd never get a 26cc weed whacker on that pencil thin fuselage. You'd have trouble with your .40. There are may more factors to consider for appropriate engine size than simply wingspan.

Look here to see what I mean:

http://www.aerospaceweb.org/question/design/q0214.shtml

The Bumble Bee II plane has a wingspan of 5 ft 6 inches - that's only 66 inches my friend, a measly 6 inches more than your dream machine. It's powered with a Continental C-85, 85hp engine, which makes your weed whacker look like a flea! And there's no way that it would fly with your .40.

Consider this: things work the way they do because that's the way they work.

Nothing in your plane was designed to accomodate that engine. So once you change the wing, change the fuse, add the stilt landing gear, add the ton of lead to balance, overload the wing and rear fuselage structure to accomodate the lead and on and on, what you've got is a mess. And it's no longer the plane with which you started. And neither will its flight characteristics be the same.

If you want a plane for a 26cc weed whacker engine, why not just start with one which is intended to use that size engine?

There are many more issues with your great plan. However, this and everyone else's comments should give you the idea.

sensei 11-13-2012 07:48 AM

RE: seaplane / weedeater help...
 
There is a thing called wing loading, maybe you have heard of it or maybe not, this airplane is supposed to come in around 6.5 lbs. that seems heavy in my opinion but whatever, with this pig of an engine you want to place on this tiny platform just what do you think the weight and wing loading will be then? Power is not an antidote for wing loading and never will be so this is a really lame idea with absolutely no valuable point to be made...

Bob

raptureboy 11-13-2012 08:05 AM

RE: seaplane / weedeater help...
 
TROLLALERT!don't feed the TROLL really guys, 40 size seaplane he wants to turn into a 26 cc 3d planehttp://www.rcuniverse.com/forum/js/f...n/drowning.gif

superfli 11-13-2012 08:41 AM

RE: seaplane / weedeater help...
 
There are 40-60 size gas engines. They are beam mounted and electronic ignition and very light. A weedwacker conversion is like mounting a boat anchor to the front. Save that for a quarter scale cub.

Good luck,

Superfli

Daniel Spurlock 11-13-2012 08:46 AM

RE: seaplane / weedeater help...
 
I say install it and when it returns to kit form you can build it bigger.There is no way that aircraft is anywhere big enough for that engine and it will never 3D not enough wing,tail or rudder how ever it will be an awsome crash.

do335a 11-13-2012 08:49 AM

RE: seaplane / weedeater help...
 

Quote:

ORIGINAL: joshrc110

www.dragtimes.com/video-viewer.php
the plane in this video i believe in 1400mm witch is not to much bigger then my seaplane and the thing flys great?

Flys great? I didn't see anything fly in that video.

The plane just sits there with the engine running.


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