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8emp on a 4

ijustwannafly

ijustwannafly

Well Known Member
While discussing the Rv4 with someone i know he is trying to convince me that most 4,s have an 8 tail on it. I had never really seen or heard of that but i also admitidly don't know much about the RV4
Is this a common thing to do? Sure would make for a fast emp build instead of the painstaking non prepunched kit
 
8 emp on a Rocket II

Some Harmon Rocket II's were built with -8 tails. The thinking being that with a longer moment arm and more power more rudder authority was needed. Other than that, I am not aware of many/any -4's with -8 tails.

I built and flew a -4 for almost 1700 hrs, and a HRII for almost a 1000 - both with -4 tails and never felt the need for more.

Just my opinion - YMMV.

David Howe
 
Thanks for the info
I did not think it was common either but this person still claims it is. He owns a builder assist business and claims it is done regularly. I think there thinking is, its not that the airplane needs more. Its that its easier to build i guess?
 
A friend of mine in Nashua, New Hampshire replaced the tail on his RV-4 with an RV-8 quick build tail. It went on fine and works fine, though it is noticeably larger when sitting next to my -4 or every other -4 I have ever seen.

His is the only one I have ever seen.
 
ijustwannafly said:
I think there thinking is, its not that the airplane needs more. Its that its easier to build i guess?
Click to expand...

I hope he understands the result on the aircraft's cg due to the extra weight. Has it been done, yes. Will it continue to happen, yes. Is it common, no. The extra 8ish pounds on the tail is no joke on an aircraft that is tail heavy already.

Do a search on the forums. I built an RV-8 tail and RV-4 tail in the same time frame and documented the weight differences in components.

Tikicarver on the forum is putting a -8 tail on his -4.
 
Did you document those results and publish them anywhere?

Id be curious to see them

He was making it sound as though it was very normal. Said he had 2 4,s in the shop right now that had 8 tails
So how bad is the aft CG issue in the 4? Does it prevent you from having a 200lb passenger?
 
Is the eight tail an improvement on the four?
I have only flown the $ that I built an an hour in a 7 for transition training.
How does a 4 compare with other RVs. As far as I can tell it is possibly the best pilots aeroplane.
 
cube out or gross out?

ijustwannafly said:
So how bad is the aft CG issue in the 4? Does it prevent you from having a 200lb passenger?
Click to expand...

An old expression in the air cargo biz. Perhaps in any cargo biz. You cube out before you gross out. Usually you are volume limited before you are weight limited.
Have you ever tried to put a 200 lb person in the back of an RV-4?
It might be hard to get him back out.
 
I have built several rockets both with 8 tails and 4 tails the 8 tail is heavier ,the vertical and rudder is larger ,elevators are aprox 1 sq, foot smaller this is strictly my opion but i feel the 8 tail is more difficult to taxi in x winds the larger vertical to me does not look as good as a 4.
given the hevier wieght ,looks and taxi issues I prefer the 4 tails .
 
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