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CATPart

Well Known Member
Not that I am wanting to make the switch to titanium legs, but I often wonder if the rocket Ti legs are the same size as the -4 long legs. By size I am referring to overall length, and diameter where it plugs into the engine mount. I usually think the rocket looks like it has longer legs than even a long legged -4. Anybody know the answer? This always crosses my mind when I am thinking about ways to remove weight from my airplane. Through my searches, it doesn't seem anybody has used rocket legs on a -4, so I am guessing it can't be done.
 
I wouldn't take any weight off the front of my 4, and most need weight on the front end. I have 2 friends with Rockets, and I will take a look, but I'm pretty sure they are quite a bit longer.
 
Short answer, no.

CATPart said:
Not that I am wanting to make the switch to titanium legs, but I often wonder if the rocket Ti legs are the same size as the -4 long legs. By size I am referring to overall length, and diameter where it plugs into the engine mount. I usually think the rocket looks like it has longer legs than even a long legged -4. Anybody know the answer? This always crosses my mind when I am thinking about ways to remove weight from my airplane. Through my searches, it doesn't seem anybody has used rocket legs on a -4, so I am guessing it can't be done.
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David,
Rocket legs are larger at the mount, much longer and only work by design on the Rocket engine mount. They are also made of titanium with the axles attached via bolts.
The stock long legs on an RV4 work very well, don't mess with success...:)
V/R
Smokey
 
If the legs are longer, they would put your main wheels further back relative to the CG if you just swapped them into an existing -4 mount. CG issues in flight aside, it would seriously affect your ground handling too.

I suppose you could put a Rocket engine mount *and* gear on a stock RV-4? But you'd have to play with the cowling a bit I'd guess.
 
The last time I saw a set of Rocket legs, they were very different than the RV4 legs. They had a completely different mounting solution.

So, you would have to change the engine mount quite a bit, or use a rocket mount like was previously suggested.
 
Also, in addition to the mounting issues previously mentioned, consider that the rocket has a stretched fuselage, and the gear are designed around that too, the shorter fuse of the 4 will cause an even higher nose up attitude when on the ground.
 
In short, no.

If you're willing to weld a completely new engine mount, including the specially machined and reamed sockets that accept the Rocket legs, spend big bucks on the legs, guess at the tire alignment, and hope that the weight of your plane is not too light such that the Rocket legs will be too stiff.... sure, you can do it.

If you want to simply replace the steel RV gear with an identical piece of titanium, you might be able to do that. You'll need to figure in the axle sockets since you can't bend the titanium like the bottom of the RV legs do.

But, like others have asked.... why? The work isn't worth the relatively small weight reduction. Maybe put in a small battery and glass instruments instead!
 
That is a unanimous no, as I suspected. I was just always curious about it from the day I heard they had Ti legs. I would never consider such a change unless they were the same size, and of course I had an actual need to replace them, which I have none. Anyway, you could likely save 10 pounds or more with such a swap if they were of identical geometry and yes Ti is more springy in this case. I have no idea what the geometry and weight of a standard long -4 gear leg is (is it hollow?), so I am just guesstimating.
 
long leg conversion

Longer legs would be good if your RV4 had short legs like mine.

Could someone make a long leg conversion for the older style RV4's? Having the pin that inserts into the engine mount machined with an offset to allow for a proper geometry? Would be simpler and easier then changing out the motor mount for the longer new style legs. Just another idea.

Tim
 
riobison,
The longer rv4 legs are also larger in diameter where they fit into the engine mount.

Custom legs could be made, but the engineering and design work to make sure it will work as wanted has not been done to the best of my knowledge.



If you wanted to discuss the possibility of making a set of custom legs, PM me and we can talk about it off line.

Thanks,
Richard
 
She got legs...

riobison said:
Longer legs would be good if your RV4 had short legs like mine.

Could someone make a long leg conversion for the older style RV4's? Having the pin that inserts into the engine mount machined with an offset to allow for a proper geometry? Would be simpler and easier then changing out the motor mount for the longer new style legs. Just another idea.

Tim
Click to expand...

Tim,.
Converting a short leg 4 to a longer leg 4 has been done many times. However, it requires a new engine mount as well as the gear. The socket angles are different as well as previously mentioned above by Rick, the socket diameter.
You will need new brake lines as the legs are...longer. The switch is a good one if you plan on keeping it, having done that change myself many years ago.
Advantages?
Aesthetics for one. STOL takeoffs, quicker rotation to airborne (higher AOA), better three point STOL landings as well. (no tailwheel-first strikes any more)
Downside, poorer over the nose taxi visibility. A bit more aerodynamic drag...
Get out your checkbook, costs about $1200 to do everything.

V/R
Smokey
 
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