Carl Goldberg Obsession 3-D

[p40fan]

I recently obtained a CG Obsession 3-D designed for a 120-140 4stroke. I am putting a 26 cc gasser in it. In checking out the firewall on the model I see it has the four mounting blind nuts installed for the supplied motor mounts. The thing I wonder about is why the mounts are offset to the left of the centerline about 1/4 of an inch (looking from the rear of the A/C). Any one got any ideas why it would be like that? I intend to install the engine inverted on the vertical center line. Thanks for looking.

[Mike Sebastien]

It is offset to the left so that when you put right thrust on the engine it centers in the cowl. I had one of these and it is a nice flying airplane. Putting a 26cc gaser on it would make it a pig because of the weight of the engine.

[p40fan]

Hi Mike: HAPPY NEW YEAR
Thanks for the info. For sure my CRRCpro GF26i is a little heavier than a 4 stroke.I did some comparisons and the crrc 26 + battery weighs in around 1250 g. An OS 1.20 is around 920g. An OS 1.60 2 stroke is listed at 925g. I can carry a smaller tank ( 10oz) with the gas and save some weight there. The engine was broke in last summer in an Great Planes Extra 300S 1.60. With a 16x 8 prop it won't quite hang in a hover but has adequate power for going vertical and my flying ability. Unfortunately I am not a 4 stroke fan ( to many moving parts to replace). What engine did you use in your Obsession? I don't normally put any side thrust in my models for no logical reason other than the saying "straight as an arrow". Do you think it would be really necessary in the Obsession?Your comments on this are greatly appreciated as I would like to get some 3-D going with it.
Thanks

[rcpilot]

I agree with Mike, 26CC gasser is not enough for doing 3D, that plane with the gasser will be around 11 to 12lbs or so, the CRRC 26 is good for something like an 8.5 to 9 lbs for 3d flying.

[Mike Sebastien]

I had a YS 1.4 on mine and the performance was outstanding. The aircraft would do everything I wanted it to do and more.

The issue I have with small gas engines is that they don't put out the power that people think they do. They are heavy, complicated and don't put out the HP. You will be lucky to get any kind of performance with a gasser on the front of the Obsession.

You have the wrong idea about 4-stokes. They are very reliable and put out great power.

I used to be a member of the Moose Jaw club from 1979 to 1981

[p40fan]

well.... I think I will take your advice and reconsider the power plant for this A/C. I want to be able to practice some different stunts. What do you think about an OS 1.60 2 stroke for this plane or maybe something like a MVVS 1.60 gas or glow or GMS120? There are a few OS 1.20 Surpasses around that would probably do the job to. Economics come into play when shopping for an engine either new or used.
I remember when you lived here. Had my own field at my farm at Riverhurst about 75 miles west of MJ. I am sure I saw you fly here as I never missed an airshow. I had been President of ERCS in Edmonton for a couple of years before I moved to Sask in 1974.
Thanks for the comments. Have to put the crrc back on the Extra now so better get at it.

[rcpilot]

well.... I think I will take your advice and reconsider the power plant for this A/C. I want to be able to practice some different stunts. What do you think about an OS 1.60 2 stroke for this plane or maybe something like a MVVS 1.60 gas or glow or GMS120? There are a few OS 1.20 Surpasses around that would probably do the job to. Economics come into play when shopping for an engine either new or used.

OS Surpass 120 will NOT be enough.
Out of all the ones you mentioned, OS160FX seems the best.
Or you can also go with MVVS Glow1.6

[OTTERTOK]

OS Surpass 120 will NOT be enough.
Out of all the ones you mentioned, OS160FX seems the best.
Or you can also go with MVVS Glow1.6

Your right Maqsood, the OS 160FX is the best pick all around. I have one of these planes and I'll be putting my 160 in it with a pump and pipe.

[p40fan]

Hi Guys
I'm back and sporting a slightly used OS 160 which is already installed in the Goldberg Obsession. Looks good.
My next question is about using a pull pull rudder setup rather than a rear mounted rudder servo. Has anyone used this setup in this type of A/C, and if so what hardware would you recommend? ie: dubro,sullivan etc., kevlar or steel lines. Its a pretty long fuse so should work quite well I think.
DennisT

[OTTERTOK]

Stick with the tail mounted servo unless your experiencing a lot of tail heavy CG that moving equipment can't fix.

[Mike Sebastien]

Tail mounted servo is better as the OS 1.6 is a pretty heavy engine and you will need weight in the aft end for balance. That is what I did with mine and I don't remember any balancing issues.

Glad to hear you are putting a OS 1.6. It is great engine and puts out lots of power. The only issue I had with the engine is it didn't have a pump.