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New RV-4 Build; Ancient but Gotta Be Done.

oystrakone

I'm New Here
Hi All,
A few months ago I acquired a '93 RV-4 in several boxes and have some questions.

The only thing on the plane assembled so far is the tail pieces by previous owner. Just the skins and the horizontal stabilizer is a L and R but not tied together. Also 'Factory' solid wing spars came with it.

As I understand from reading, it seems I should be doing the wings first.

Is it safe from a gross weight standpoint (I don't know the weight and balance) to try to add about 10 gallons of gas to each wing?

My thought is to add a wing rib with lightning holes and a second pick-up where the outboard tank wall is supposed to be to maintain wing structure at that station, and then put the outboard tank wall outboard of that by about 8" to get that extra few gallons of gas? I realize Experimental means I can do anything I want, but I'm not interested in going too far outside the box.

Any thoughts would be greatly appreciated, thanks in advance.

Travis
 
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Hi Travis,
I built my -4, and if I had to do it over again, I would use RV-6 fuel tanks. The cg, and extra weight won't be an issue, as you can adjust your fuel load based on your mission requirements. Get to building, it is an incredible machine.
My mods are-
Moved roll bar back two inches (6'2", 245 pounds, and I fit perfectly)
Removed an inch from bottom of instrument panel
Two RV-10 vents installed
Todds canopy
Wing tip lockers as shown in RVator
 
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A few things to keep in mind..

You have a great start and will love the -4. I built mine , S/N 2667, a late 80's tail kit and bought my wing and fuselage kits around '93. I have never heard of a "Factory Solid Spar". I built my spar , which is a build up of many components to a very robust design. Vans advertised the "factory spars" as an option which are actually just kit spars sent to a vendor (Phlogiston) whom assembled it. they are easily identified by their gold anodizing. The wing spars are fit and drilled with a matched set of steel splice plates as well as the center fuselage bulkhead, which is why building the wings before the fuselage is pretty much mandatory. Make sure you have all the matching parts. Going forward , if you dont have the finish kit, you will get the new style longeron wedments , long gear and epoxy cowl, wheel pants and fairings. As Michael said,and I also did, move roll bar back( determines pilot seat back position), trim panel bottom. I am 6'1", and I fit fine. The extra fuel of the -6 tanks , I would also do in hind sight, but my missions are usually less than 2 hrs, so the stock 32 gallons is fine for me...Now get building!
 
Baffle

Hi

It is possible to do this, as they say there is more than one way to skin a cat..

Just extending the tank to a six tank is problematic because you have the phlosigon spar and the web that attaches the tank is already fitted. That limits the tank width.

In the UK max all up weight is limited to 1550lbs. I know you can set your own in the states but Van is against this. The thing that limits the 4 is that all up weight. Adding 70lbs of fuel limits passenger load by that amount. Most 4s are between 950 and 1050 lbs depending on what instruments engine and prop are fitted.

So I would think carefully before adding more weight.
 
The separate horizontal stabilizer halves might be an issue. The HS-409 spar bars get riveted to the spar webs across the joint between them and tie them together in the back, but they extend outboard too.

It might be hard to rivet them to the webs if the skins are already on.

If you meant the elevator halves then it's okay.

Dave
 
Step one (for this rv-4)

Thanks for the thoughts guys. Fate had it that a guy came by the shop on other business last week who happened to have RV building experience. Thanks to him I have direction now on 'what to do first' so; since the previous owners did the tail feathers I am undergoing a steep learning curve on the wings.

1. fluting pliers to make all ribs flat
2. line up ribs at right angle to spar
3. study/learn how to drill and debur holes
4. decide on gas tank plan

Now I'm looking to trade some of my scrap boat aluminum for an Avery tool kit. Boat aluminum is 5052H32, and extrusions are 6061T6. Channel, sched 40 pipe, flat bar, angle, and some 1"x1" square tube with .125 wall.

ps. I just read the directions on how to attach pictures to posts. Doesn't seem to work. Any tricks?
 
Van's practice kit for the toolbox might be a handy thing to try first. Also helpful for me was to make a channel of aluminum (or find a likely-looking channel like part in the kit, buy another, and use that) and rivet cap strips to the flanges. Lots of drilling, deburring and dimpling practice that way.

My philosophy is to first try to do something on a part or scrap that's not intended for the plane. I wreck enough airplane parts as it is.

Dave
RV-3B, now on the fuselage.
 
Links to pictures:
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The boat is done and shipped to Alaska. But sold another for a June delivery and hopefully my crew will allow time for me to dig into this rv4.

Does anyone have rv4 parts laying around?
Not sure what all I need yet, but..
2ea A-403PP-L (Spar)
16ea A-710 skin stiffeners
basically all the aileron pieces, except the skins, I have those.

If not, is the best way to buy individual part #'rs from Vans?
 
Hi Travis,
I built my -4, and if I had to do it over again, I would use RV-6 fuel tanks. The cg, and extra weight won't be an issue, as you can adjust your fuel load based on your mission requirements. Get to building, it is an incredible machine.
My mods are-
Moved roll bar back two inches (6'2", 245 pounds, and I fit perfectly)
Removed an inch from bottom of instrument panel
Two RV-10 vents installed
Todds canopy
Wing tip lockers as shown in RVator

Thanks for the info Micheal, this is probably the scenario I'll try to do... is there a way to convert my -4 tanks to the -6 tanks? what is the difference between? Since my -4 kit is the slow build kind I have loose skins and haven't installed the caps or fastened anything permanently yet it seems like the only option of extra gallons is to extend the tank outboard? is this correct?
 
What's This Hole in My Firewall

I purchased my RV-4 project from an estate sale.
Builder deceased so can't ask questions.

What might the 2" hole in the firewall pictures below be used for???

wkPEwWi.jpg

4lmE8Nl.jpg
 
Hi Travis,
Steve Arnold mentioned that with the Phlogiston Spar(which is what I have), you can't modify to the -6 tanks because of the mounting flange. Wouldn't worry about the extra gas. I make it from NH to NC on a tank of fuel, and am ready to stretch by then anyways.
I believe skin stiffeners for the ailerons are fabricated from 3/4"x3/4" x .032 aluminum strips. That's just going from memory, so I could be wrong. I wish I lived close by, I miss building (except for fiberglass).
 
I purchased my RV-4 project from an estate sale.
Builder deceased so can't ask questions.

What might the 2" hole in the firewall pictures below be used for???

wkPEwWi.jpg

4lmE8Nl.jpg


I'm just working Firewall forward on my -4 and all I can think is the heater door like Gil said. Though yours appears to be to low to use as the lower engine mount tube is in the way. Maybe you can build a stainless patch and run your fuel line there.
 
Hi Travis,
....
I believe skin stiffeners for the ailerons are fabricated from 3/4"x3/4" x .032 aluminum strips. That's just going from memory, so I could be wrong. I wish I lived close by, I miss building (except for fiberglass).

Yes, but not quite as hefty. :)

They are 5/8 x 5/8 x 0.025 angles simply bent from flat sheet.

Apparently changed (at least for the -6 models) in 1994 from 0.016 thickness
 
Larger tanks can be done. Done over 15 years ago

I forget exactly how I did it. I remember partially deconstructing the Phlogiston spar (drilling out the big rivets adding an additional flange and reriveting) Also added some little square blocks between upper and lower spar laminations. Got the info from John Harmon.

Steve
 
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