RV-4 tall gear & firewall weldments

Gentleman -
Considering the purchase of an RV-4 and looking for some insight. In my quest for RV-4 wisdom I discovered that if the airplane has the 180hp and a C/S prop it should also have the tall gear option and the firewall weldment mod. At least that’s what I read in an older Kit Plane article. The airplane I’m considering has the 180hp and the C/S prop but the seller is unsure if it also has the tall gear and weldments. Is there a tell tell sign just by looking at the airplane if it has the tall gear? Also with the cowl off what or where are the firewall weldments?
V/R,
Joe

The weldments are inside the cockpit in the lower corners behind the firewall. I have an RV-4 with 200+ hp, CS and short gear.

Thanks, what purpose do the weldments serve? Do all RV-4’s require weldments are just the early ones?

nyav8or said:

Thanks, what purpose do the weldments serve? Are there any other advantages to the tall gear option besides the obvious prop clearance?

Click to expand...

The stronger weldments are more desirable as they connect the firewall to the rest of the plane. As for the long gear, it also allows for slower landings, closer to a full stall. I have the long gear, and I can easily touch tail first.. I wish it was even taller! The short gear planes fly nice too, maybe less gear shake? And lighter too?

Weldments..

The "weldments" are a steel fitting/corner joint that connect the aluminum longerons to the firewall and engine mount structure. The first generation weldments were a split type, the newer are more of a pocket design. Some older ones develop cracks, and can be modified with a repair/upgrade. the newer style are much more durable and have been standard in the kits for many years now. Long/Short gear is a long standing debate, mine is long because that was standard when I built mine. I've flown both, and wouldn't let it be a deal breaker. If the plane has a long prop (72-74), you will need to watch your deck angle if hard bounce or unusual tail high situation. The picture attached is a "new style longeron weldment" on mine. They are located bottom and top corners of the firewall about where your heels rest .

Here’s my experience/understanding as an owner of a sweet short gear 160hp CS -4:
-Our weldments were replaced before we owned it. They hadn’t cracked; the PO just wanted it done. If not cracked, the old split weldments can be shored up with doublers inside and out. Much easier than replacing.
-at prop overhaul we had our prop shortened from 72” to 70” for an inch of extra clearance, but it flew at 72” for decades. I never felt uncomfortable when it was 2” longer but I’ve never been cavalier with my landings. If not for a worn pitch-change block it would still be 72”. The repair, IRAN, and blade shortening was $3K. Didn’t notice any change in performance with the shortened blades.
-the flatter 3 pt attitude makes it easy to fly it onto the deck in 3 pts. The 1-2 mph of extra speed at touchdown adds confidence in a gusty crosswind. I almost always land 3 point. If I happen to touch mains first I roll the tail up a few inches into a tail low wheel landing. On 3 points the view over the nose is better than a 172. Unless your plans include regularly dropping it into short rough fields short gear is more than fine.
-if I found a nice -4 at a fair price with old weldments and short gear I wouldn’t hesitate to jump on it!
-I covet your chance of flying behind 180 hp and a CS prop!! Good Luck!!

Huge help… I’m now more confident in what I’m talking about and looking at with the weldments. My previous RV-6 suffered a cracked motor mount and everything was replaced with RV-7 gear and parts. Was thinking this was along the same line, but now I see it’s totally different. Still uncertain on how to spot a tall vs short gear from a distance, guessing that is just experience. Thanks for taking the time to explain and share pictures.

This is copied from a VAF thread from years ago. Given measurements helped me when I was searching for a 4 and a seller wasn't sure. Nothing wrong with short gear, but tall gear and HD weldments were a must for me.

Here's info from Joe Blank at Van's...

From a part number standpoint, the U-415 is the tall gear leg, and the U-401 is the short gear leg. The taller gear leg overall length is 50.50" and the length from the upper end to the bend (axle) is 42.65". My guess is that the short gear leg will be about 2"-3" shorter.

I'm not sure what other info you are needing at this point, but the taller gear leg raises the aircraft by 2" and requires a different engine mount. Hope this helps.
Thanks

Joe
Vans Aircraft