[klovning]

This is going to be a long post bear with me.

The cooling ramp design has changed in the last few years - some people with older planes had a diffrent design and instructions (i.e. the hinge is gone from the aft part of the cooling ramp in my plans). So I think the design was updated but not the instructions.

Assembling the forward floor (F-890 and the F-893 supports) the plans say to :

Then for the floor supports (F-893)

After trimming the the cooling ramp - the instructions say

Later when playing with the firewall's lower angle (F-801D-1)

Now follow the red line

The dimples and countersinks run in opposite directions!

Worse yet - I can't fix them - if they were all just dimpled - I could re-dimple in the other direction.

My solution - I've called van's, bought some AN426AD-5 and AN426AD-6 rivets. They said it would be OK to drill the holes to larger size - countersink for larger size and then rivet.

I just wanted to warn everyone else. --- I also will need to build a shim for the cooling ramp - F-890 - F-801D-1 interface -- so when the outboard 2 cooling ramp holes are on top of the F-893 angle, the middle 7 rivets will line up.

 

[thilokind]

I ran into almost the same issue, which resulted in two new Forward Ribs in my case. You also need shim between the cooling ramp and the skin between the two Foreward Ribs...

Thilo

 

[chaskuss]

Don't do what Jason & I did.

Jason
I see that some things never change. I have the older, non matched hole kit. I see that Vans still doesn't tell you to make an .063" shim to be placed between the F-801D angle and the ramp skin. When using the shim, the 9 holes in the F-801D do not need to be countersunk. Like you, I realized this after the fact. I filled mine with epoxy. The shim needs to have it's 9 holes countersunk, instead.
Charlie Kuss
PS I just checked my builders log. I changed my plan due to fears that the epoxy would not hold up during the riveting or during use. I removed the epoxy and fabricated two .032" shims (to be stacked together). This allowed me to dimple those 9 holes in each of the two shims.

 

[RVG8tor]

QB same deal I think.

I was just goint to rivet my ramp on today. The forward holes on the firewall are already done (that is the foward part of the firewall. The nine holes at the bottom of the firewall flange are dimpled but the outer most holes are not dimpled or drilled to size. I was racking my brain as to why they were not drilled, I was thinking of just putting in AN470 rivets on the two outer holes, I don't see why these would have to be flush rivets. I was also looking at the angle the ramp skin takes due to no shim, the only thing I can think of is that the plans (new ones) call for you to apply proseal in this area before riveting, maybe the proseal supports the .063 difference.

Anyone see any reason why the two outer most holes in the foward part of the cooling ramp need to be flush? I can bend the ramp back enough to machine CS the floor rib, and then I can dimple the ramp holes but not wanting to creat work for myself I thought the simple answer was to use a universal rivet here.

Link is a picture of cooling ramp outer hole I am talking about.

http://www.mykitlog.com/users/display_log.php?user=rvg8tor&project=403&category=0&log=79701&row=1

 

[chaskuss]

What is the state of your F-801D?

I was just going to rivet my ramp on today. The forward holes on the firewall are already done (that is the forward part of the firewall. The nine holes at the bottom of the firewall flange are dimpled but the outer most holes are not dimpled or drilled to size. I was racking my brain as to why they were not drilled, I was thinking of just putting in AN470 rivets on the two outer holes, I don't see why these would have to be flush rivets. I was also looking at the angle the ramp skin takes due to no shim, the only thing I can think of is that the plans (new ones) call for you to apply proseal in this area before riveting, maybe the proseal supports the .063 difference.

Anyone see any reason why the two outer most holes in the forward part of the cooling ramp need to be flush? I can bend the ramp back enough to machine CS the floor rib, and then I can dimple the ramp holes but not wanting to create work for myself I thought the simple answer was to use a universal rivet here.

Link is a picture of cooling ramp outer hole I am talking about.

http://www.mykitlog.com/users/display_log.php?user=rvg8tor&project=403&category=0&log=79701&row=1

Hi Mike,
I should have had you look underneath my firewall area when you came to visit last month. Those outer two holes do not "have" to use flush rivets. Are the rivet holes in your F-801D angle countersunk yet? If not, leave them as they are. Make an .063" shim as I mentioned in my previous post. It the holes are already countersunk, make two .032" shims and dimple them. Use either style shim to prevent having the ramp skin from getting "kinked" where it would otherwise step down from the inner floor ribs to the F-801D angle. Kinks at these two points will create stress risers, which WILL crack in the future.
My best suggestion is to drill the ramp skin off the firewall and secure the ramp skin on with (mostly) flush screws and nut plates. I originally planned to rivet my ramp in place, but decided to add work for ease of maintenance/repair in the future.
I posted photos of how I did this at:

http://www.vansairforce.com/community/showthread.php?t=29475&highlight=exhaust+ramp&page=2

I have the older style ramp design, so am not sure how this would correspond to what you have. Can you post a photo of your situation?

The Proseal is NOT intended to fill the 1/16" gap. It's purpose is to try to keep the exhaust fumes (containing corrosive acids) from getting between the floor skin, floor ribs, stiffeners and the ramp. The high potential for corrosion here is a big reason to make that ramp removable. Better to find minor corrosion during the annual condition inspection, rather than to have your feet go through the floor 5 or 10 years down the road!
Charlie Kuss
PS This is just another oversight on the design of the 8/8A. Have you ever considered how you would ever tighten/inspect the AN3 nuts and bolts which retain the lower sub longerons to the lower firewall weldments? Vans sure didn't! It's easy to make access hole/covers to fix that oversight. See below

 

[RVG8tor]

Rivet vice nut plates

Charlie,

I plan to rivet mine IAW the plans, there are not that many rivet to remove if I ever have to take it off. Also, my plans call for adding proseal underneath as well as making a bead all along the sides, this thing would be very difficult to remove and I think without the proseal that would be more vibration which would lead to cracks. I guess one could forgo the proseal and just spray some corrosion-X behind the ramp each year. Here is a shot of the DWG I have, I think the new ramp does away with the hinged attach method at the aft end of the ramp. There is no call out for a shim, I intend to call Van's and ask if this is an oversight. Sure would be nice if they posted some simple PDF files with fixes to the errors in the plans. They seem to do it with the RV-12 and 10 but no other kits.

 

[chaskuss]

Rivets versus Nut Plates

Charlie,

I plan to rivet mine IAW the plans, there are not that many rivet to remove if I ever have to take it off. Also, my plans call for adding proseal underneath as well as making a bead all along the sides, this thing would be very difficult to remove and I think without the proseal that would be more vibration which would lead to cracks. I guess one could forgo the proseal and just spray some corrosion-X behind the ramp each year. Here is a shot of the DWG I have, I think the new ramp does away with the hinged attach method at the aft end of the ramp. There is no call out for a shim, I intend to call Van's and ask if this is an oversight. Sure would be nice if they posted some simple PDF files with fixes to the errors in the plans. They seem to do it with the RV-12 and 10 but no other kits.

Mike,
Thanks for the photo of the ramp drawing for the Mk I design ramp. It appears that the only change that Vans made was to replace the hinge. The ramp will still vibrate because it has no support structure on the sides. It's only secured to the belly at the front and the back. This allows it to flex and bend to much.
Use the blind rivets if you so choose. Like you say, they are not hard to drill out. I think Vans recommends applying Proseal between the inner floor ribs and the ramp for two purposes. #1 It will help keep the exhaust gases out. #2 It will help secure the ramp to the rest of the structure. I would not suggest you omit the Proseal along the sides, UNLESS you consider improving the mounting of the ramp by giving it support structure on the sides. This can easily be done by riveting a piece of angle to each inner floor rib, using blind rivets. See the photos of how I did this (you don't really need flush rivet to secure the angles). They are on the link in my previous post.
Dan Horton also offers a redesigned ramp which is much more securely attached to the fuselage structure. His idea is definitely less involved than mine.
You are the builder, so it's your decision.
Charlie Kuss

 

[RVG8tor]

Short on time

Mike,
Thanks for the photo of the ramp drawing for the Mk I design ramp. It appears that the only change that Vans made was to replace the hinge. The ramp will still vibrate because it has no support structure on the sides. It's only secured to the belly at the front and the back. This allows it to flex and bend to much.
Use the blind rivets if you so choose. Like you say, they are not hard to drill out. I think Vans recommends applying Proseal between the inner floor ribs and the ramp for two purposes. #1 It will help keep the exhaust gases out. #2 It will help secure the ramp to the rest of the structure. I would not suggest you omit the Proseal along the sides, UNLESS you consider improving the mounting of the ramp by giving it support structure on the sides. This can easily be done by riveting a piece of angle to each inner floor rib, using blind rivets. See the photos of how I did this (you don't really need flush rivet to secure the angles). They are on the link in my previous post.
Dan Horton also offers a redesigned ramp which is much more securely attached to the fuselage structure. His idea is definitely less involved than mine.
You are the builder, so it's your decision.
Charlie Kuss

Charlie,

Thanks for the advice but I am trying to force myself to stick to the plans in an effort to minimize the time until I am flying. I was going to do some mods to the consoles, some of the stuff you sent me but then I thought about it and that can be done later. After I am flying there will be months at a time when I can't fly, I will fine tune my plane then. So for now my rule is build it per the plans unless it is something that makes sense to do now.

Cheers

 

[chaskuss]

Attention Jason

Jason,
I just tried to reply to your PM, but you have no more space to receive my reply. Please delete some old messages from your Private Message box.
Charlie Kuss
10:40am EDT
5/24