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  #1  
Old 03-04-2017, 09:06 PM
RV-4 RV-4 is offline
 
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Question RV-8 TAIL ASSY ON A ROCKET

Hello Gents

Any harm in installing a RV-8 Tail assy on a Rocket?? I know of one and was wondering if there might be any do's & don'ts..

Thanks

Bruno
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  #2  
Old 03-05-2017, 07:55 AM
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N395V N395V is offline
 
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Which Rocket?........................................... ............................................
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  #3  
Old 03-05-2017, 09:03 AM
flynwest flynwest is offline
 
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Default 8 tail

Bob Mills put one on his Rocket 6
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Old 03-05-2017, 09:04 AM
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Toobuilder Toobuilder is offline
 
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I didn't build it, but my Rocket has an -8 tail.

I understand from Mr. Mills that the taller tail is a speed penalty. Out of concerns over the higher speed of the Rocket and potential susceptibility to flutter, I also removed the rudder trim tab the builder installed. It was quite sloppy and I have not missed it one bit.
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Last edited by Toobuilder : 03-05-2017 at 09:10 AM.
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  #5  
Old 03-05-2017, 09:49 AM
RV-4 RV-4 is offline
 
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Thumbs up RV-8 TAIL ON A ROCKET

Milt

It is a HR 2, it looks good on the airplane but was wondering if it could affect the aircraft in any way...

Bruno
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  #6  
Old 03-05-2017, 10:52 AM
Steve Barnes Steve Barnes is offline
 
Join Date: Jul 2008
Location: Santa Rosa, CA
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Default I have a RV8 empennage fairing on my Super Six too

When I built my Super Six (sister ship to bob Mills) I had an unused RV 8 empennage and installed it during the build. Has worked perfect for 1250 hours. I not sure if Bob has an RV 7 or 8 empennage on his 6.

Steve
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  #7  
Old 03-05-2017, 11:32 AM
Tom Martin Tom Martin is offline
 
Join Date: Jan 2005
Location: Ontario, Canada
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I built two HRIIs using the RV8 tail. They fit fine and I used the 8 tail for two reasons. It was easier to build then the 4 tail and also it had a counterbalanced fin. I have not flown a HRII with a RV4 tail but my RV4 had, at times, a tail wags the dog kind of yaw situation. My rockets with the 8 tail did not have this syndrome. That is the good news.
On the negative side:
The 8 tail is heavier and we really do not want that extra weight back there.
Also the elevators on the 8 are adequate but a wider chord would be better. I could run out of trim in some loading conditions and I wonder how well the plane would fly in an engine out scenario.
Although I never made any measurements I wonder if the RV7 elevators would work on the 8 stab?
While building the 8 tail I would recommend reinforcing the forward VS attach point as well as the forward HS stab spar. My HRIIs had stock engines and were fine with the stock tail, however if you plan on higher speeds be aware that you may be in uncharted territory.

It is great to see some renewed interest in Rockets. They are a joy to fly and I can hardly wait for spring weather!
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  #8  
Old 03-05-2017, 12:21 PM
jrs14855 jrs14855 is offline
 
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Default Tail Wags the dog

That is normally an issue with the folded trailing edge skins. I had a hangar neighbor years ago with a then brand new RV4 and it was a pretty significant issue based on his description. I looked at it and the skin at the trailing edge was bulged out significantly. I told him to squeeze the trailing edges and he said the problem went away. This discussion seems to come up repeatedly.
Once again I recommend Barnaby Wainfans excellent article on this subject a few years ago in Kitplanes.
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  #9  
Old 03-05-2017, 03:32 PM
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F1Boss F1Boss is offline
 
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Default It will fit but...

I would suggest a few beef-ups to stiffen the structure for Rocket speeds - make your own .040 spars for example. Also the elevs are a bit on the small side, as obvious on a 200HP/metal prop RV8. It won't 3-point solo without some ballast (I suggest a 120lb PAX in the back seat - possibly one on the female side of things) or 1/2 flap, but to some that characteristic is not a problem.

Other than that, it fits up fine! Use 1"X1" angle at the H Stab fwd spar attach in the fuselage at the #10 bulkhead (under the aft deck plate). There is more to the aft fuselage story...

Remember the airframe Vne is a TAS number.

Carry on!
Mark
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  #10  
Old 03-05-2017, 03:43 PM
scsmith scsmith is offline
 
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Quote:
Originally Posted by jrs14855 View Post
That is normally an issue with the folded trailing edge skins. I had a hangar neighbor years ago with a then brand new RV4 and it was a pretty significant issue based on his description. I looked at it and the skin at the trailing edge was bulged out significantly. I told him to squeeze the trailing edges and he said the problem went away. This discussion seems to come up repeatedly.
Once again I recommend Barnaby Wainfans excellent article on this subject a few years ago in Kitplanes.
Wait! Don't confuse a dutch-roll yaw oscillation with a vague or bi-stable rudder issue. Two very different things. A poorly formed trailing edge will cause the latter, but not the former.
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