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How light can a RV4 be?

rvnor

Member
Hey
What is your empty weight of your RV4? Which engine and equipment?
Vans says 903-913 lbs, with Lyc 320 and VFR instrumentation? The Lyc 320 engine is 306lbs +?
My question is do you think it will be possible to build the RV4 with an empty weight down to 830 lbs, 70+ lbs down from std weight.
No paint, polish only, minimum interior and instrumentation VFR only, lightweight seats, lightweight battery, choose prop by weight, fixed pitch, no vacum, el ignition, etc… But no compromise on safety
Then the engine, the Lyc 200 series would be to weak and the ROTAX series to weak and light?
The Titan X340 is estimated to be from 260-290 lbs and the Lyc 320 is from 306 lbs. There might be 50 lbs weight saving from only the engine.
Is this a realistic project?
Will there be problems with the weight and balance by removing 50 lbs firewall forward? Possible to move the engine further forward? Options on engine mounts?
Your thoughts?
Thnx
 
1018 lbs, O360 metal fixed pitch, vfr panel, oxygen bottle, antique heavy Lowrance GPS, interior side panels.
 
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980 lbs, O-360, carbon Sensenich, VFR glass, manual trim & flaps, two axis autopilot, cloth upholstered seats, no other upholstery.
 
995lbs O-360, hartzell metal C/S, standard battery in standard location, single skyview system, with one MGL V16 com.

bob burns
RV-4 n82RB
 
830 pound RV4?

"My question is do you think it will be possible to build the RV4 with an empty weight down to 830 lbs, 70+ lbs down from std weight?"

No
 
"My question is do you think it will be possible to build the RV4 with an empty weight down to 830 lbs, 70+ lbs down from std weight?"

No

You might be able to get there with the UL520 for power. It is 108kg (236lb) with starter and alternator putting out 180-200 hp. I would guess you would have to make a longer mtr mt to move the engine fwd to keep the CG where it should be. No primer or paint and minimal everything. Might be possible.

My 4 was 940 lb, O-320, Prince carbon prop, skytech LW starter, 17lb battery, steam gauges, no autopilot, manual trims and painted.

Take off 70 for the engine, 30 for paint/primer, 10 for a lithium battery, 10 for instruments, another 10 for skybolt fasteners, LW tailwheel and extra interior stuff = 130lb + 20 for extra engine mt metal and cowl glass = 110lb off the 940 and you are there...hypothetically of course.
 
As others have mentioned, the more you remove up front, the more your already tail heavy RV-4 will get.


N94VF weighed 940# using calibrated digital scales.
Sensenich GA prop
painted, no primer
light cushions
glass panel
standard battery

I'm sure swapping to a lightweight battery would save some weight, but I'd rather fly than work.
 
If it is a 600 pound airframe what engine prop combination comes in at 230 pounds, My RV-4 came in at 1043 pounds with an 0360 a Hartzell constant speed leather interior fully loaded Gucci and I would never go back.
 
I bought my RV-4 and it was bare bones basic to keep it as light as possible, weighed 887 pounds. I covered it with vinyl, replaced steam gauges with one EFIS, no lights at all, strictly VFR and last time I weighed it, it was 902 pounds. I have an O320 with a Sterba prop on the front, no oil cooler and it’s only primer inside, barely any paint on the aircraft. I like it this way and I don’t believe it can be built much lighter.
 
I think it's realistic IF you're willing to fly with a very lightweight (and new and expensive) engine, and to significantly extend the engine mount and cowling in order to get the CG in the right place.
  • The UL350iS makes 130hp and weighs 173 lbs.
  • Rotax's 915iS makes 141hp and weighs 187 lbs.
  • The UL390iS makes 160hp and weighs 220 lbs.
You'd be sacrificing spin resistance due to the longer nose ahead of the CG. And if you go with less than 160hp, you'd (of course) be sacrificing takeoff and climb performance and some cruise speed. But it's doable. And as a side benefit, you'd be able to use mogas, which might offset the cost of these fancy engines over the life of the airplane.
 
903

My 4 is down to 903 as of a couple of months ago: painted (no primer); narrow deck; Pacesetter 200; Dynon Skyview; EarthX battery; McCreary tires; Bendix mags; 4 pipe exhaust. How can I lighten it? J
 
Weight

This requires thinking WAY outside the box:
Move the engine forward to solve CG issue
Lycon has some ideas for weight reduction on Lycoming.
Carbon fiber cowl, wheel pants, spinner, wingtips etc.
Titanium gear legs.
Magnesium wheels
Drill lightening holes in brake discs.
"Lamb" tires
Fuselage tank only??
Titanium tail spring.
Starter only with power plug for starting.
Remove rear seat controls??
Removeable rear seat cushions.
 
Fill the tubes with helium, go on a diet, fly naked, remove the tail wheel and replace it with skid so you can then also remove main wheel brakes…
 
My 4 is down to 903 as of a couple of months ago: painted (no primer); narrow deck; Pacesetter 200; Dynon Skyview; EarthX battery; McCreary tires; Bendix mags; 4 pipe exhaust. How can I lighten it? J

bendix mags 4.5 lbs inpulse, 4.0 without

light speed 2.5 lbs
 
Weight a minute!

GREAT discussion!
Way back in the day my brand new RV4 tipped the FAA scales at 915 lbs. I took this as a victory until I thought, why do I need an electrical system, starter, battery etc for MY mission? Good question, so I removed all the above and yes, my unpainted, ND 0-320/Sterba HH radio no transponder Vans masterpiece weighed in at 889 lbs, a bantam weight fighter!
Practical?
For me yes, ergonomically oriented, maybe not. But who cares, right, I built it per my own specifications right?
Hmmmm....
Well I did eventually compromise adding back lightweight electrical system components, ditching the Mags for EI and settling for 925lbs full up with paint.
So how did the " light flight " characteristics differ from the latter?
Not a huge noticeable change but the 889lb 4 was a delight, great aerobatics, 1v1's with my F16 Bros, amazing STOL etc.

However, even heavy RV4s are delightful...my 1100lb+ HR2 with 300HP was a case in point!!! Yeeha!
:)
Smokey
 
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Empty wt 925. IO 360 (9:1 compression), dual SDS EI and FI. 2 lithium batteries, 1 alternator. Minimal paint--tailfeathers and fiberglass parts. 3 blade FP Catto prop. Trig radio and transponder, VFR panel with Garmin 660. ADS-B in and out. MGL Engine monitor, and MGL instrument for AS, Alt and VS. Climbs pretty good....
 
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