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RV8 wing root strakes

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Veteran8

Member
Hi … I own an RV8 which has vortex gens on the wing LE and tail TE bottom … the aircraft flies beautifully but I can’t do 3 pointers because the tail stalls during the landing … I have heard of wing strakes pic attached that were available from Frank Medler and Brad Heintz and have emailed them but got no reply .. can any member update me on their current e mail address and advise me about the strakes further? and how to get a set for my a/c ? I will be at Oshkosh AV 24 and my e mail is [email protected] tel +61417715008
Many thanks .. Raja Suri

1718841841873.png
 
Veteran8 said:
I own an RV8 which has vortex gens on the wing LE and tail TE bottom … the aircraft flies beautifully but I can’t do 3 pointers because the tail stalls during the landing …
Click to expand...

Welcome Raja. Many owners three point their -8 without difficulty. I suspect you're not the builder, so a basic question. Have you measured the elevator displacement angle at full up and full down?
 
Veteran8 said:
Hi … I own an RV8 which has vortex gens on the wing LE and tail TE bottom … the aircraft flies beautifully but I can’t do 3 pointers because the tail stalls during the landing … I have heard of wing strakes pic attached that were available from Frank Medler and Brad Heintz and have emailed them but got no reply .. can any member update me on their current e mail address and advise me about the strakes further? and how to get a set for my a/c ? I will be at Oshkosh AV 24 and my e mail is [email protected] tel +61417715008
Many thanks .. Raja Suri
Click to expand...
Whats your CG loading?
 
DanH said:
Welcome Raja. Many owners three point their -8 without difficulty. I suspect you're not the builder, so a basic question. Have you measured the elevator displacement angle at full up and full down?
Click to expand...
Hi Dan thanks for your reply … you’re right I’m not the builder .. no I haven’t measured the elevator displacement .. what should it be ? I also own a Citabria and lots of tail wheel experience but still find it difficult to 3 point the 8 as I run out of elevator . I always fly solo with a 30 lb ballast in the rear baggage comp… which has improved
the situation considerably . That’s why I thought strakes will help
 
Veteran8 said:
Hi … I own an RV8 which has vortex gens on the wing LE and tail TE bottom … the aircraft flies beautifully but I can’t do 3 pointers because the tail stalls during the landing … I have heard of wing strakes pic attached that were available from Frank Medler and Brad Heintz and have emailed them but got no reply .. can any member update me on their current e mail address and advise me about the strakes further? and how to get a set for my a/c ? I will be at Oshkosh AV 24 and my e mail is [email protected] tel +61417715008
Many thanks .. Raja Suri

View attachment 65054
Click to expand...
See this post, as there are two different types of strakes. https://www.vansairforce.net/threads/tail-shake.227172/#post-1770826

Frank Melder no longer makes them. Terry Burch was making the carbon fiber strakes shown in the linked post above. 'Conversation' me and I'll pass on Terry's contact info. Or you can get a pair of Twin Cessna nacelle strakes, which is the one shown in your picture.

Also, here is a link to an excellent KitPlanes article by Nigel Speedy on the effect of wing and HStab vg's on the RV-8. They don't do much of anything at low speeds, but reduce the top speed by about 5 KTAS,

www.kitplanes.com

Vortex Generators on an RV-8

Do they really make a difference? By Nigel Speedy.
www.kitplanes.com www.kitplanes.com
 
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DanH said:
Welcome Raja. Many owners three point their -8 without difficulty. I suspect you're not the builder, so a basic question. Have you measured the elevator displacement angle at full up and full down?
Click to expand...

DanH said:
Welcome Raja. Many owners three point their -8 without difficulty. I suspect you're not the builder, so a basic question. Have you measured the elevator displacement angle at full up and full down?
Click to expand...
Hi Dan measured the elevator disp .. 29 deg up , 14 down
 
Raja, here are the control surface deflections, from the Vans manual:

Control Surface Deflections.jpg

As you can see, you're short on down elevator travel (14 measured vs 20 minimum), although middle of the acceptable range in up elevator travel. Obviously the ability to raise the nose to stall attitude is not a function of down elevator, but the rigging does suggest things are not quite right. Let's check two details.

First, elevator stop contact points. The elevator arms should contact the points detailed below with a nice firm clunk, before any kind of resistance or binding can be detected in any other part of the elevator control system. That includes stick contact with seat backs and cushions. The deflections should be within range with the arms in firm contact as described. If necessary, these fuselage stops are filed as needed to allow appropriate elevator travel.

Elevator Stops.jpg

Elevator Stops 2.jpg

Second, an assembly check. It's possible for a builder to miss an important note on the assembly drawing. Inspect around the bottom flange of the horizontal stabilizer rear spar. There should be a 3/16" space between the aft deck plate and the underside of the spar. If the rear spar was drilled to the vertical attach bars without a 3/16" spacer to set the gap (drill bits are common), the HS incidence is wrong.

HS Mounting.jpg
 
DanH said:
Raja, here are the control surface deflections, from the Vans manual:

View attachment 65067

As you can see, you're short on down elevator travel (14 measured vs 20 minimum), although middle of the acceptable range in up elevator travel. Obviously the ability to raise the nose to stall attitude is not a function of down elevator, but the rigging does suggest things are not quite right. Let's check two details.

First, elevator stop contact points. The elevator arms should contact the points detailed below with a nice firm clunk, before any kind of resistance or binding can be detected in any other part of the elevator control system. That includes stick contact with seat backs and cushions. The deflections should be within range with the arms in firm contact as described. If necessary, these fuselage stops are filed as needed to allow appropriate elevator travel.

View attachment 65068

View attachment 65069

Second, an assembly check. It's possible for a builder to miss an important note on the assembly drawing. Inspect around the bottom flange of the horizontal stabilizer rear spar. There should be a 3/16" space between the aft deck plate and the underside of the spar. If the rear spar was drilled to the vertical attach bars without a 3/16" spacer to set the gap (drill bits are common), the HS incidence is wrong.

View attachment 65072
Click to expand...
Many thanks Dan I’ll get it seen to .. really appreciate your inputs … if you’re in Oshkosh 24 this year let’s catch up my number is +61417715008 .. Raj Suri
 
As a new guy, you'll want to attend the RV Social and meet everybody. Search "2024 RV Social" here on VAF.
 
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