A

AllanB

Member
I have the opportunity to buy a second-hand RV4 kit approx. 10 yrs old, only 70 hours work on it, the rest (complete less engine) still in original boxes!
It has a Phlogiston spar but is before the pre-drilled kits.
So, how much more difficult will it be to build, how much longer will it take to build it, and are there more pitfalls in the older kits?
Can the tips be used for fuel tanks?
Thanks in advance, I am amazed at the support provided on this site.
Aussie Newbie.
 
I am completing an RV-4 which I purchased in about the same state as the one you are considering. It had the horizontal stab skeleton built. Was a complete 1989 vintage kit with a Phlogiston spar.

How much more difficult will it be to build, how much longer will it take to build?
I started the RV-4 about a year after completing my RV-6A. The experience, tools, and jigs from the RV-6 made the work go faster, although the "need to fly" the -6 slowed progress. The RV-4 is more difficult to build than the RV-6 (which was not prepunched). The instructions and plans are not any where near the quality of the newer kits and there are more parts to fabricate.

I paid about 25% the cost of a new RV-4 kit but I have spent about $3000 on parts to bring it up to new standards. This new parts included:
new engine mount with long gear legs
new prepreg short nose constant speed cowl
13 inch spinner to match the new cowl
new style wing tips (not necessary but I like them better)
heaver 0.020 skins for the elevators and rudder
new pressure recovery wheel fairings
fiberglass gear fairings​

The newer CAD designed kits with prepunched skins and ribs would be much easier to build; however, since in my experience the airframe requires about 50% of the effort (assuming you do the panel, firewall forward and paint) this would not double the total effort. You can see a graph of RV-6A build time on my web site - 1200 hours on the airframe with a total of 2400 hours. On the RV-4, I spent 900 hours building the airframe and will complete the project in about 1900 hours. The shorter time reflects knowledge gained from the -6, having an existing infrastructure and maybe not tracking as closely.

Are there more pitfalls in the older kits?

I didn't encounter any pitfalls - there are a lot of -4 flying. I think it is the best looking RV and probably the best handling.

Can the tips be used for fuel tanks?

The tips would require significant modifications to use for fuel but it could be done. It would be better to use a large RV-6 wing tank since the wings haven't been built yet.

I hope this helps. Good luck on your decision.
 
Are there more pitfalls in the older kits?
I didn't encounter any pitfalls - there are a lot of -4 flying. I think it is the best looking RV and probably the best handling.
Can the tips be used for fuel tanks?
The tips would require significant modifications to use for fuel but it could be done. It would be better to use a large RV-6 wing tank since the wings haven't been built yet.



The -4 IS the best handling RV (If you don't consider the -3)!

Actually if you are considering going to the -6 tanks, you might even try the -8 tanks. They are longer yet. However this may be quite a modification regarding the -4 spar.

Mel...DAR
 
RV4 - old kit

... and are there more pitfalls in the older kits?

Allan - I am new to the -4 having sold a -9A last year and have started on a -4.

The thing that nobody has mentioned - and its not a show stopper for you but you need to know - is that there have been some changes to the firewall attachment probably since your prospective kit was shipped. The longerons terminate in steel fittings and bolt/rivet to the firewall. The thickness of the steel and to some extent the design of these parts was changed because the parts were cracking. The whole firewall area is still the design weakness of the -4 though I am building one. I am in the UK and we fly mostly off grass so its a bit more bumpy than a runway. This tends to be when a problem occurs. The parts you may need to replace wont cost much and I think VANS may replace them for free.

I would suggest you would be better off on the -4 thread. At least review it because you will find the issues you need to be aware of. I have been running them down over the last 12 months.

Go for it!
Steve
#4478
UK
 
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