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  #1  
Old 11-25-2022, 09:03 AM
BrianP BrianP is offline
 
Join Date: Sep 2022
Location: Winnipeg,MB
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Default Snap Rolls

Iím sure this is a topic that has probably been actively debated in the past. I canít seem to find past threads. My understanding is that Vans discourages snap rolls in the RV8. Some RV owners Iíve talked to say itís no issue and that the tail construction is extremely strong. I heat bought an RV8 with inverted systems to do some aerobatics so am interested in the topic. Can someone point me to a thread where this has previously been covered?
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  #2  
Old 11-25-2022, 09:22 AM
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rv8ch rv8ch is offline
 
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Snap roll or hammerhead or tail slide?

https://www.aopa.org/news-and-media/...ue--snap-rolls

I've read some feel a bit uncomfortable with the hammerhead or tail slide, mainly due to the sounds coming out of the tail area, but I don't recall anyone saying that there is a problem with snap rolls.
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  #3  
Old 11-25-2022, 09:36 AM
flyride flyride is offline
 
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Location: Sacramento, CA
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Hammerhead is a low energy maneuver and can be done in RV's with sufficient pilot experience with no impact to airframe. A lot can go wrong with a hammerhead, however from an aircraft control standpoint.

Before you tail slide, take a look at the flight control attachments on a dedicated acro aircraft and then compare with the RV.

Personally, I do not snap RVs due to the monocoque fuselage construction. The stresses on the airframe substantially exceed that of a normal low-energy spin entry.
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  #4  
Old 11-25-2022, 09:55 AM
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Dan 57 Dan 57 is offline
 
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Quote:
Vans discourages snap rolls in the RV8
Ain't RV-8 specific though... Vans discourages snaps in any RV.
Re tail slides, it is one of the figures thought of provoking cracks in the skins of the elevator and rudder...

I sure don't wanna sound condescending, but for anyone thinking of flying aeros, please take some tuition beforehand. There are flight instruction and courses, and that is IMHO, a major safety precaution. Those RVs (even the non -8...) accelerate pretty fast, and have light controls.

Maybe one also remembers that aluminum can only withstand a finite amount of repetitive fatigue cycles, making the material de facto not the best for this use. Witness current unlimited aircraft, none is made out of aluminum...
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  #5  
Old 11-25-2022, 09:59 AM
Desert Rat Desert Rat is offline
 
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Location: Wichita KS
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Quote:
Originally Posted by rv8ch View Post
Snap roll or hammerhead or tail slide?

https://www.aopa.org/news-and-media/...ue--snap-rolls

I've read some feel a bit uncomfortable with the hammerhead or tail slide, mainly due to the sounds coming out of the tail area, but I don't recall anyone saying that there is a problem with snap rolls.
It's in the service bulletin about the rv7 rudder change. Maybe elsewhere as well, but I know you can find it there.

"They were designed primarily as sport/cross country airplanes with sufficient performance and control authority to safely perform basic recreational aerobatics such as loops and rolls. We do not consider aerobatic maneuvers such as high speed multiple snap rolls and tail slides, which can impose high airframe loads to meet our definition of sport aerobatics."

The go on to suggest maneuvers that might be specifically prohibited in the Ops limits and lists both snap rolls and tail slides as examples.
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  #6  
Old 11-25-2022, 10:24 AM
spatsch spatsch is offline
 
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Location: Denison, TX
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So I did a lot of the acrobatic maneuvers during flight testing with a camera facing the tail.

- Hammerheads when flown properly are no issue at all.
- Tailslides I didnít do after looking at the hinges
- SNAP rolls I did do but they were the only maneuvers in which the tail moved substantially. All other acro maneuvers the tail was rock solid.

After observing that I stopped doing SNAP rolls. Can you do them? Sure. Will they put a lot of fatigue on your tail? yes. In fact one guy who was doing lots of SNAPs in his RV had his horiz stab attachment bolts elongate requiring replacement at every other annual.

I think the RV is a great sportsman class acrobatic airplane and I had lots of fun competing with it.

In intermediate class where snap rolls are required your are really stretching it. Both in mission envelope and literally. People have done it but expect some additional maintenance.

Oliver
p.s. The only reason I can think of people recommending against hammerheads is that an unexperienced pilot might botch it and get into a tail slide or inverted spin. The first one is not good for your RV the second might confuse an unexperienced pilot with disastrous consequences.
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  #7  
Old 11-25-2022, 10:42 AM
spatsch spatsch is offline
 
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One more comment on the legal side. During phase 1 flight testing every acrobatic maneuver that is allowed later must be demonstrated to be save and be part of the log book entry. So its up to the person doing the phase 1 testing if in your particular RV-8 snap rolls are legal. There are lots of RV-8s in which they are not.

So if snap rolls are listed and assuming the person signing the entry didnít lie there was at least one snap roll flown in your RV.

Oliver
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  #8  
Old 11-25-2022, 11:16 AM
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Mel Mel is offline
 
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Quote:
Originally Posted by spatsch View Post
One more comment on the legal side. During phase 1 flight testing every acrobatic maneuver that is allowed later must be demonstrated to be save and be part of the log book entry. So its up to the person doing the phase 1 testing if in your particular RV-8 snap rolls are legal. There are lots of RV-8s in which they are not.
So if snap rolls are listed and assuming the person signing the entry didnít lie there was at least one snap roll flown in your RV.
Oliver
Good to remember that this does not have to happen during the initial Phase I.

You may place the aircraft back into Phase I to do aerobatic maneuvers after you are more comfortable in the aircraft.
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  #9  
Old 11-25-2022, 12:39 PM
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RV8JD RV8JD is offline
 
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In general, the aerobatic RVs are not specifically designed for snap rolls, and certainly not for tail slides. But note that there are several very experienced and qualified pilots who snap roll their RVs successfully, including Van himself, and in competitions. But they are very careful and know what they are doing.

See the article "An Aerobatic Epistle", by Van himself:
https://drive.google.com/file/d/16-I...ew?usp=sharing
Another article by Van himself on competition aerobatics, "IAC Aerobatics in RVs", with a good addendum on preparing your RV for aerobatics by Ron Schreck. Van again addresses snap rolls and tail slides in the article:
https://drive.google.com/file/d/1AGr...ew?usp=sharing
And note the "Aerobatics" section on Van's website:
https://www.vansaircraft.com/flying-an-rv/
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  #10  
Old 11-25-2022, 12:44 PM
jrs14855 jrs14855 is offline
 
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Location: Lake Havasu City AZ
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Default acro

While probably not a significant risk, hammerheads do pose some risk of evolving into an inadvertent tailslide. Even when practicing a lot and doing intentional tailslides it is pretty rare for the airplane to slide backwards more than one airplane length. But if you actually slid backwards a long ways it could cause major damage in an RV or even structural failure. If the engine quit during or just before a hammerhead the airplane could tailslide enough to cause damage
Learn these maneuvers with an instructor in an airplane that is approved for tailslides. In any airplane have a plan to exit the maneuver in the event of engine failure or partial loss of power. For the hammerhead simply pitch the airplane nose down and keep apply neutral rudder.
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