CG Chipmunk engine/muf and covering Question  
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CG Chipmunk engine/muf and covering Question - 10/16/2007 4:16:35 PM   
Zipperneck



Posts: 160
Joined: 9/15/2003
From: Plan de la Tour, FRANCE
Status: offline 		Gonna try to hit two birds with one stone on this one.

I've got a CG Chipmunk that I plan to build and am considering putting an OS 91 Surpass II in it. I see that Slimline makes an inverted pitts muffler for this engine (ref. 4012).

What are your thoughts on this combo considering looks, cooling, etc. - the thing costs around 90 bucks.

Also - I'd like to cover the plane with something like solartex so I can paint on the paint scheme.

Your thoughts on this? I'm tired of having iron-on coverings come off after a while. If I went the monokote route, can I spay the whole thing down with a polyurethane varnish to seal in all the stickers and stuff??

Thanks in advance for any input!

Zipperneck

       Post #: 1

RE: CG Chipmunk engine/muf and covering Question - 10/16/2007 4:18:59 PM   
Zipperneck



Posts: 160
Joined: 9/15/2003
From: Plan de la Tour, FRANCE
Status: offline 		Just an additional thought...
I ordered a set of fiberglass wheel pants and cowling from AeroFiberTech - hope it was the right choice.

Zipperneck

(in reply to Zipperneck)
       Post #: 2

RE: CG Chipmunk engine/muf and covering Question - 10/16/2007 5:33:22 PM   
hrrcflyer


 

Posts: 494
Joined: 4/11/2006
From: Carrollton, VA, USA
Status: offline 		Zipperneck,

If you mount the engine inverted, the stock muffler may work since the cowl is somewhat narrow. If not, see if you can get a flexible pipe to go between the motor and the muffler. I know they make them for Saito four strokes, but I'm not sure about OS. If they do, you can mount the muffler anywhere inside the cowl and connect it to the engine with the flexible pipe.

I'm sure you know this, but if you decide to paint your plane, use thin coats to minimize the weight penalty of the paint versus Monocote. If you go the Monocote route, you will only need to seal the edges between the colors and around the decals. I've had my best results using Balsarite for covering to seal the edges on my planes. If you're not familiar with Balsarite, its a clear liquid you paint on with a small model paint brush. I've also heard that clear fingernail polish does the same thing, but I haven't tried it.

Good luck with your build and keep us posted with your progress.


_____________________________

Fly safe and have fun!!
David

(in reply to Zipperneck)
       Post #: 3

RE: CG Chipmunk engine/muf and covering Question - 10/16/2007 5:38:03 PM   
Zipperneck



Posts: 160
Joined: 9/15/2003
From: Plan de la Tour, FRANCE
Status: offline 		Hrrcflyer,
Thanks for the flex tip. I'll check that it -may be a more cost-effective way to get an in-cowl muffler setup.

I'll check into the balsaright method also.

Tnx!
Zipperneck

(in reply to hrrcflyer)
       Post #: 4

RE: CG Chipmunk engine/muf and covering Question - 10/16/2007 6:29:39 PM   
MinnFlyer



Posts: 19636
Joined: 4/22/2002
From: Willmar, MN, USA
Status: online 		The Goldberg Chipmunk and an OS 91 are made for each other. Great Combo!

On mine, I mounted the engine sideways and just let the stock muffler stick out, but you can also swing the muffler inside the cowl and let it vent out an opening in the bottom

_____________________________

Mike B.
AMA# 42400 www.gettingairborne.com

"Those are my principles. If you don't like them, I have others." - Groucho Marx

(in reply to Zipperneck)
       Post #: 5

RE: CG Chipmunk engine/muf and covering Question - 10/16/2007 7:35:26 PM   
Campgems


 

Posts: 1923
Joined: 2/18/2006
From: Arroyo Grande, CA, USA
Status: offline 		The pitts creates a bit of a problem in a tight cowl, and even in an open one. These photos are of one mounted on a Magnum 91 that is in my Super Aeromaster. I don't know how it's going to run, I'm not quite finsihed with the model yet. I think that I would use either a flex pipe or one of the optional headers for the engine the next time. It seems that Slimline could have routed a header into the end of the muffler and cut down the bulk a bit.

Don

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(in reply to Zipperneck)
       Post #: 6

RE: CG Chipmunk engine/muf and covering Question - 10/16/2007 7:41:58 PM   
MinnFlyer



Posts: 19636
Joined: 4/22/2002
From: Willmar, MN, USA
Status: online 		And here is an OS 91 Surpass with the muffler turned inside the cowl

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_____________________________

Mike B.
AMA# 42400 www.gettingairborne.com

"Those are my principles. If you don't like them, I have others." - Groucho Marx

(in reply to Campgems)
       Post #: 7

RE: CG Chipmunk engine/muf and covering Question - 10/16/2007 7:55:08 PM   
Campgems


 

Posts: 1923
Joined: 2/18/2006
From: Arroyo Grande, CA, USA
Status: offline 		Mike that cowl would be turned into a conopy with the pitts. I'm not sure what the metal is in their mufflers, but a little hacking could turn it into a usuable muffler. I've already butchered my cowl so I'll stick with it as it now stands. Next time though

Don

(in reply to MinnFlyer)
       Post #: 8

RE: CG Chipmunk engine/muf and covering Question - 10/16/2007 9:37:59 PM   
Zipperneck



Posts: 160
Joined: 9/15/2003
From: Plan de la Tour, FRANCE
Status: offline 		Minnflyer,
Great idea! I hadn't even considered a side mounted arrangement... that's a good idea. I'll have to consider that possibility....

Thanks!
Zipperneck

(in reply to Campgems)
       Post #: 9

RE: CG Chipmunk engine/muf and covering Question - 10/17/2007 8:40:33 AM   
Zipperneck



Posts: 160
Joined: 9/15/2003
From: Plan de la Tour, FRANCE
Status: offline 		Hrrcflyer,

I checked into the Balsarite product on the Tower Hobbies website. Apparently this product is painted onto the wood before the Monokote is applied. What I'm looking for is something to put on top of the covering to keep it in place so no fuel gets under the edges and eventually lead to it coming off.

Also, apparently Balsarite cannot be shipped by air... Since I'm in France and will be taking a load of RC stuff back with me after visiting the States, I may have a hard time transporting the stuff. I have no idea of this stuff can be shipped surface (by boat)....

There may be an equivalent to this product in the "old country" - I'll have to look into that. Thing is, things are so damn difficult to get here - in a respectable time frame and at reasonable cost.

Zipperneck

(in reply to hrrcflyer)
       Post #: 10

RE: CG Chipmunk engine/muf and covering Question - 10/17/2007 12:37:23 PM   
MinnFlyer



Posts: 19636
Joined: 4/22/2002
From: Willmar, MN, USA
Status: online 		Zipperneck, If you use MonoKote brand covering, once the covering is finished, dip a Q-Tip in acetone and run it around all of the seams.

That will hold them down forever, but it doesn't work on Ultracote/Oracover

_____________________________

Mike B.
AMA# 42400 www.gettingairborne.com

"Those are my principles. If you don't like them, I have others." - Groucho Marx

(in reply to Zipperneck)
       Post #: 11

RE: CG Chipmunk engine/muf and covering Question - 10/17/2007 12:43:02 PM   
Zipperneck



Posts: 160
Joined: 9/15/2003
From: Plan de la Tour, FRANCE
Status: offline 		Ouch - acetone around my planes gives me shivers...

I suppose the word "sparingly" should be applied here.

Funnily enough, most of the hobby outlets here in France sell Oracover or Solartex (kinda cheapo and doesn't adhere well).

I'll have to order some monokote for the Chippy and give it a try. They also have the matching pain spray can, but I wouldn't be able to take that on the plane with me (along with my shampoo and aftershave!). Ground shipment might work, though.

Thanks for the idea!

Zipperneck

(in reply to MinnFlyer)
       Post #: 12

RE: CG Chipmunk engine/muf and covering Question - 10/17/2007 12:46:22 PM   
MinnFlyer



Posts: 19636
Joined: 4/22/2002
From: Willmar, MN, USA
Status: online 		You can safely use Acetone on covering. It is very agressive on MonoKote's adhesive, but it doesn't hurt the covering at all.

In fact, it's a great way to remove CA glue from covering.

_____________________________

Mike B.
AMA# 42400 www.gettingairborne.com

"Those are my principles. If you don't like them, I have others." - Groucho Marx

(in reply to Zipperneck)
       Post #: 13

RE: CG Chipmunk engine/muf and covering Question - 10/17/2007 5:05:51 PM   
Campgems


 

Posts: 1923
Joined: 2/18/2006
From: Arroyo Grande, CA, USA
Status: offline 		You need to be careful with bubles arond the edges. When I trimmed out my 4*60, I had a couple places where the trim wasn't really stuck down like I thought. As I applied the acetone. I could see it wick under the trim. I pushed it down with my finger and discovered that the adheasive is also the color. I ende up with a couple ugly spots along the edge. Make sure you seal the edges well with an iron before doing the final seal with the acetone.

I was using one of the pipettes for applying CA. THe acetone was flowing to freely from and that caused part of the problem I later discovered the tip to use a cotton swab to apply it. It would be nice to have a felt point to like a marking pen to apply the acetone.

Don

PS, one more tip to keep in mind. Cleaning the model at the end of the flight day with Windex with Amonia will cause the edges of the monokote to lift. The Amonia is what desolves it to begen with.


(in reply to MinnFlyer)
       Post #: 14

RE: CG Chipmunk engine/muf and covering Question - 10/17/2007 5:19:19 PM   
Zipperneck



Posts: 160
Joined: 9/15/2003
From: Plan de la Tour, FRANCE
Status: offline 		OK, thanks for the tip. I use denatured alcohol to clean the plane down at the end of the day. Do you think that could cause the trim to come up?
Zipper

(in reply to Campgems)