hi all,
saw these posts , how smart or safe is this? apparently a lot of ppl seem to be doing this

www.rcuniverse.com/forum/m_7912128/anchors_7912189/mpage_1/key_/anchor/tm.htm#7912189

www.rcuniverse.com/forum/m_7912128/anchors_7922376/mpage_1/key_/anchor/tm.htm#7922376

so according to the above posts, can we put a lets say 90 4stroke on a 46size yak 3d? has anyone here done something like this?
your views plz

regards
carloz

googling a bit more shows that using a 61 engine on a 46 model for 3d is common

I have a 55 2 stroke on a .46 size profile Yak 54.  Overpowered, but not to the scale being discussed in these threads.

Remember that 4-stroke engines for equivalent 2 stroke ones are always higher displacement.

Mr. Anwar may I know what size of propeller you are using for your Yak 54 with 55 2 stroke engine? I am asking you because I have same thing but because of my accident I didn't get chance to fly it yet. I think you're talking about the model which is on your profile picture, if yes then I also have same model with same engine setup.

12x3.75 currently. I can go a bit higher, but this seems to be more than enough for now.

12x3.75 or APC 12.25x3.75 Sport Propeller?

The APC one. 

It is 12.25 X 3.75. U can also use a 12 X 4 and u'll get the same performance.
I have a ASP 91 on a 60 size plane. Am flying it with an 14 X 6 prop, but will soon try and change it to a 15 X 4 and try some prop hangs.
Just saw a beautiful plane at Amby Valley with a set up most will frown upon.
A 46 size high wing trainer with a 91 4 stroke engine. It does a prop hang just after take off and maybe u could just take ur thumb off the throttle and it would hang on its own.
Doc

apart from increase in weight, wing loading and probably shift in CG, any other cons of overpowering?

another con i think would be to keep a firm hand on the throttle, improper or full thrttle would obviously result in losing the model..

regards
carloz

Yes the biggest con would be the increased probability of structural failure in case VNE for the aircraft is exceeded

VNE ?  

http://www.rcindia.org/rc-general-topics/rc-jargon-the-mega-list/

en.m.wikipedia.org/wiki/V_speeds?wasRedirected=true

heres a more detailed explanation

regards
carloz

In simple terms VNE = Velocity Not to be Exceeded