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Old Apr 14, 2014, 07:18 AM
North Simcoe Flyers
rcwings's Avatar
Midland, Ontario, Canada
Joined May 2007
798 Posts
Thanks guys...believe me I was a click away from ordering that glass cowl. What stopped me was the price of shipping to get it up here. Was just as much as the cowl itself, so had second thoughts.

tailskid2 - You must have had some cooling issues did you? Just wondering if you used an approximate 2-1 ratio of vent hole (exit air) size to intake air size openings? Even with that, some cowls just don't allow proper airflow for cooling.....so point taken and will consider!
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Old Apr 14, 2014, 11:45 AM
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tailskid2's Avatar
USA, AZ, Phoenix
Joined May 2003
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I blocked that exit and opened the bottom a bit and never had a problem with overheating.
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Old Apr 15, 2014, 04:52 AM
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pablojaime's Avatar
Israel, Ashdod
Joined Dec 2009
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Yes, 2 to 1 ratio, I opened the two front holes and made a big one in the bottom exit, never had a heat problem, even on idle.
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Old Apr 15, 2014, 09:50 AM
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United States, FL
Joined Mar 2012
436 Posts
Engine choice?

I posted a blog on the 13th of this month, received 1009 views but no comments. I have since found this thread and hope to read through it in the next few days. Anyhow, the one question I have is, will an OS 91 Surpass fit under the cowl? I already have one and would like to use it in the RV-4. I also have an OS 48 four stroke that is currently being used in a Seniorita, but I would install it on the RV-4 if that is a better choice. Thank you in advance for your comments and I'm sure I will learn a lot as I thumb through the build log. P.S. I have not purchased the kit yet, but plan to very soon
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Old Apr 15, 2014, 10:17 AM
North Simcoe Flyers
rcwings's Avatar
Midland, Ontario, Canada
Joined May 2007
798 Posts
Hello rcflyinff,

You will not be able to stuff that OS 91 FS into the RV-4 cowl. You will also be faced with trimming the cowl away for the muffler. Will not be a clean fit. It will also be too much power for that plane in my opinion! I have two of those engines, and would not recommend it for this bird. Will be overpowered and will add unwanted weight, as well as prop clearance may be an issue.

Can't really comment on the 48. It may be a better choice over the 91, but will likely fly more scale like. The 48 is on the low end of the power choice for the RV-4.

Hope that helps.
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Old Apr 15, 2014, 12:50 PM
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United States, FL
Joined Mar 2012
436 Posts
Thank you rcwings. I figured that the 91 would be to big. I'd rather not go with the low end either. Guess I will have to do some bartering for a 60-70 range four stroke. I'd rather have more power than not enough. Are there any bad flying characteristics to this plane? How about flaps? Are they worth installing? This plane looks so nice and I can't wait to purchase and get started.
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Old Apr 15, 2014, 01:32 PM
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los36's Avatar
United States, TX, The Colony
Joined Nov 2012
235 Posts
You could try to find one of these ...
http://www.rcgroups.com/forums/showthread.php?t=1512743

I'm not sure about the GP RV-4, but it fits completely inside the H9 RV-8 cowl. Well, the needles stick out the top of the cowl.
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Old Apr 15, 2014, 06:38 PM
North Simcoe Flyers
rcwings's Avatar
Midland, Ontario, Canada
Joined May 2007
798 Posts
Quote:
Originally Posted by los36 View Post
You could try to find one of these ...
http://www.rcgroups.com/forums/showthread.php?t=1512743

I'm not sure about the GP RV-4, but it fits completely inside the H9 RV-8 cowl. Well, the needles stick out the top of the cowl.
I believe that the discontinued H9 RV-8 is slightly larger. Very nice engine though!!!
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Old Apr 15, 2014, 10:10 PM
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United States, TX, The Colony
Joined Nov 2012
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Quote:
Originally Posted by rcwings View Post
I believe that the discontinued H9 RV-8 is slightly larger. Very nice engine though!!!
Well, your model has a 5" longer wingspan. That doesn't mean that the cowl is larger, but it's probably similarly sized. Think of it as fitting two .50 four strokes in there. If one will fit, then the twin will fit.
2 servos in the tail should balance it right out.
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Old Apr 15, 2014, 11:55 PM
North Simcoe Flyers
rcwings's Avatar
Midland, Ontario, Canada
Joined May 2007
798 Posts
Quote:
Originally Posted by los36 View Post
Well, your model has a 5" longer wingspan. That doesn't mean that the cowl is larger, but it's probably similarly sized. Think of it as fitting two .50 four strokes in there. If one will fit, then the twin will fit.
2 servos in the tail should balance it right out.
I thought the little 60 Saito twin would be a sweet fit in the GP RV-4. Might be marginal for power though...and for the price, I was not willing to chance it.
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