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wingspan99

Active Member
I have an RV-4 with an O-320 E2G 160hp (8.5:1 pistons) and Sterba 68x74 (perfect size) wood prop and it flies solo with the elevator tips up about 1/4" and is limited to 185lbs in the rear seat, so I'd like to add about 20lbs of nose weight. I've seen prop crush plates at over $360 and harmonic balancers at $600, are there any inexpensive solutions out there, like lead that can be bolted to the engine or existing crush plate? I have lots of lead...
-Tom in CO
N40MB
 
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MOVE ITEMS!

Man try not to add usless weight(lead) Move anything you casn forward. put on a light tail wheel. Make a mount and move the battery to under the engine... anything to add usefull weight forward...
 
I put a Saber 20 pound crush plate on my O-360-A1A. It came with new prop bolts and cost $293 including shipping.
 
add weight forward?

Tom, I have the identical set-up in my RV-4 (engine, prop, passenger weight limit), and have to agree with Tom about adding addition weight if it can be avoided since any added weight is less fuel to keep from going over gross.
 
Nose weight

If I move the battery to the firewall it will move forward 12".
I could move the ELT forward, it's in the baggage compartment.
Is there a lighter tailwheel than stock? 1lb difference would be significant way back there.
It seems to me that only the RV-4's with the O-360 and CS prop have the correct balance point and power loading for carrying baggage and standard pax sizes. Maybe a longer engine mount would be the answer for the sufficient but lighter O-320?
 
Data point

I have the Sensenich prop and an O320. Prop weighs something like 35 lbs.
I can carry a 230 lb passenger (if I don't let the fuel get too low).
 
wingspan99 said:
I have an RV-4 with an O-320 E2G 160hp (8.5:1 pistons) and Sterba 68x74 (perfect size) wood prop and it flies solo with the elevator tips up about 1/4" and is limited to 185lbs in the rear seat, so I'd like to add about 20lbs of nose weight. I've seen prop crush plates at over $360 and harmonic balancers at $600, are there any inexpensive solutions out there, like lead that can be bolted to the engine or existing crush plate? I have lots of lead...
-Tom in CO
N40MB
Click to expand...

Tom,

You can buy the Inertia Ring for $115 and that will get you 12 lbs on the nose. A prestolite starter also would add weight if you're running a lite-weight starter and you can pick them up cheap. Just a couple of ideas... :) One other thing you can do is change the incidence of your horizonal stab a tad...
 
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Inertia Ring

Thanks for the ideas everyone.
What is an inertia ring? A heavier starter ring?
I have the big heavy starter.
The Sensenich prop, is it the RV prop they offer? I've thought about that prop.
It has the increased blade twist necessary to run RV speeds.
The lighter tailwheel without the side plates would save 6oz way back there.
-Tom
 
wingspan99 said:
Thanks for the ideas everyone.
What is an inertia ring? A heavier starter ring?
I have the big heavy starter.
The Sensenich prop, is it the RV prop they offer? I've thought about that prop.
It has the increased blade twist necessary to run RV speeds.
The lighter tailwheel without the side plates would save 6oz way back there.
-Tom
Click to expand...

It replaced the Harmonic Balancer Mark Landoll sold, he also sells the inertia rings. The bolt up directly to the flywheel.
 
Lead solution

Tom,

Sometimes you just can't move any more stuff to the nose. I have the light weight Whirlwind prop and can't even put a put a weight on the prop flange due to the Lightspeed ignition pickup interfering. I added 17 pounds of lead like this: Cut about a foot of 2-inch automobile exhaust pipe. Weld a cap on one end and drill about four 1/4-inch holes along the length of the pipe. Insert four AN-4 bolts through the holes from the inside and fill the pipe with lead. Weld a cap onto the other end. Paint as desired and put a label on it like "flux capacitor catalitic energizer". :D Now you can bolt the pipe to your engine mount useing adel clamps on the four bolts secured to the pipe.
Yes, it is preferable to move weight from the tail to balance your airplane, but when that's no longer an option, this does the trick.
 
"flux capacitor catalitic energizer"


When I first started work many years ago, I was sent to the stores for several items. These were:

1. A long weight

2. A box of sparks for the grinder.

3. A skyhook.

For the first item, I was kept waiting ages and the item never showed up.
The second item was in a cardbord box which always escaped if you opened it and the third item, well don't we all wish we had one of those.
 
Swimming pool and Lead in Pipe

When I was in Aviation High School in Long Island City, NY, getting my high school diploma and my A&P license, the seniors would try to sell keys for the swimming pool on the roof to the freshmen.
I like Smokey's pragmatic approach, I will probably try something like that, I have an electric lead melting pot, I can just fill a pipe and try it, at least I will get an idea of where my CG needs to be, and then I'll work on lightening or improving the usefulness of the weight later, maybe a prop hub weight, that seems the simplest and furthest forward. Do the prop hub weights smooth out the engine at cruise any?
Maybe I can make a prop hub weight by attaching a lead ring to the prop crush plate? Countersink six bolts from the prop side, and bolt it on? I have an electric lead melting pot for making sinkers.
-Tom in CO
 
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Homemade lead nose weight

Ok I got moving on this and I took 22lbs of lead sinkers and melted them in a 2lb coffee can which is 6" in diameter, on top of a propane camping stove. Evidently the cans are welded nowadays instead of soldered so the can took the heat fine. 20 min later I had a can full of molten lead. I leveled the top edge of the can with a bubble level so it would be pretty close to balanced, then let it cool. Now I have a 2.5" thick disc 6" in diameter. If I get longer bolts I can either countersink it 1.5" and bolt it on in lieu of the crush plate. I have 7/16" diameter prop bolts, and I think with the 160hp piston upgrade I am supposed to go to 1/2" bolts so I think I'll do that now and replace the inserts on the prop flange with 1/2" inserts. What kind of bolts are used for prop bolts? Can I use Grade 8 bolts? When the lead cools I'll cut the can away, and drill the bolt pattern it in a drill press, then balance it somehow. I'm pretty sure the lead will fit in the spinner I have too.
-Tom in CO
 
I use SCUBA bean bag weights.
My weights are not that far forward but what I've done is place a them on the inside firewall cabin floor.
I do this on long cross country flights when i know I'll be in aft cg when low on fuel & near gross weight on start of flight.
 
wingspan99 said:
Ok I got moving on this and I took 22lbs of lead sinkers and melted them in a 2lb coffee can which is 6" in diameter, on top of a propane camping stove. Evidently the cans are welded nowadays instead of soldered so the can took the heat fine. 20 min later I had a can full of molten lead. I leveled the top edge of the can with a bubble level so it would be pretty close to balanced, then let it cool. Now I have a 2.5" thick disc 6" in diameter. If I get longer bolts I can either countersink it 1.5" and bolt it on in lieu of the crush plate. I have 7/16" diameter prop bolts, and I think with the 160hp piston upgrade I am supposed to go to 1/2" bolts so I think I'll do that now and replace the inserts on the prop flange with 1/2" inserts. What kind of bolts are used for prop bolts? Can I use Grade 8 bolts? When the lead cools I'll cut the can away, and drill the bolt pattern it in a drill press, then balance it somehow. I'm pretty sure the lead will fit in the spinner I have too.
-Tom in CO
Click to expand...
This just doesn't sound right. :confused: Please consult your nearest engineer.
 
Countersink

I don't think the countersink would work either, I'm going to just put it between the prop crush plate and the prop with longer prop bolts. I am my nearest engineer and always have been with great results.
 
wingspan99 said:
I don't think the countersink would work either, I'm going to just put it between the prop crush plate and the prop with longer prop bolts. I am my nearest engineer and always have been with great results.
Click to expand...

Tom,

Please keep in mind that lead is not a structurally stable material. Any machine shop could make what you describe out of steel for little $$$.
 
ronschreck said:
Tom,

Please keep in mind that lead is not a structurally stable material. Any machine shop could make what you describe out of steel for little $$$.
Click to expand...

When considering cost don't forget to figure in new prop bolts. Grade eight bolts that size aren't exactly cheap. I still think my solution was the best one for me. One phone call to Saber and $293 later my tail heavy plane was happily centered within it's CG limits.
 
Steel does sound better

I guess lead would squeeze and deform under vibration and allow the prop bolts to loosen. After I put the 23lbs lead casting on a lathe and turned it down to a balanced size, it was 17lbs. 5 3/4" diameter and 1 3/4" thick was the size. Maybe a local machine shop could make a 21lb steel weight for less than the $300 at Sabre?
 
Boy, I sure hate adding lead weight to airplanes. Sometimes its unavoidable, but I go way out of my way to do it as little as possible.

Here's a question: What thickness are the elevator skins?

Based on the available 3-view, each elevator skin has about 4.7 ft^2 of area. For the four skins in .020" thickness, that is about 5.4 lbs of aluminum. But in .016" thickness, it's down to about 4.3 lbs. And every lb of elevator skin saves about 1 lb of balance mass for equivalent mass balancing. So making new elevator skins in .016," taking out a bit of lead, and painting them lightly could save you 2 lbs back there.

The rudder has about the same skin area as the elevator, so doing it would save you another half pound. But I think it's not mass-balanced on the RV-4, so there's no mass balance savings; you just get the half pound. But a total of 2.5 lbs removed from the tail is nothing to sneeze at.

Of course, there are many reports of cracking with the .016" skins. But there are also many high-time RVs with .016 tail skins and no cracks.

It's a thing to think on.

Thanks, Bob K.
 
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