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Old 08-22-2021, 10:31 AM
rvnor rvnor is offline
Join Date: Aug 2008
Location: 70'N ENNA Norway
Posts: 17
Default How light can a RV4 be?

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?
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Old 08-22-2021, 10:54 AM
Taltruda Taltruda is online now
Join Date: Oct 2017
Location: Las Vegas, NV
Posts: 876

1018 lbs, O360 metal fixed pitch, vfr panel, oxygen bottle, antique heavy Lowrance GPS, interior side panels.
Las Vegas
RV-4 flying…
RV-8 empenage finished 10-2020

Wings Started.. 11-2020

Last edited by Taltruda : 08-24-2021 at 07:24 AM.
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Old 08-22-2021, 12:13 PM
Scott Hersha Scott Hersha is offline
Join Date: Jan 2005
Location: Cincinnati, OH
Posts: 1,955

980 lbs, O-360, carbon Sensenich, VFR glass, manual trim & flaps, two axis autopilot, cloth upholstered seats, no other upholstery.
RV6/2001 built/sold 2005
RV8 Fastback/2008 built/sold 2015
RV4/bought 2016/sold/2017
RV8/2018 built/Sold(sadly)
RV4/bought 2019 Flying
RV6/Used kit purchased 2021 building
Cincinnati, OH/KHAO
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Old 08-22-2021, 06:50 PM
n82rb's Avatar
n82rb n82rb is offline
Join Date: Jan 2007
Location: fort myers fl
Posts: 1,066

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
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Old 08-22-2021, 07:07 PM
patterson patterson is offline
Join Date: Mar 2005
Location: Queen Creek AZ
Posts: 587
Default 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?"

RV-4 N8ZD Sold
Phat -4 under construction
regular VAF donor despite being exempt
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Old 08-22-2021, 09:29 PM
RV7 To Go RV7 To Go is offline
Join Date: May 2011
Location: Ontario, Canada
Posts: 321

Originally Posted by patterson View Post
"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?"

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.
RV4 - Bought 2013 Sold 2017 after 450 hrs
RV7 - Built in 6.5 yrs & Flying 2017
RV4 - Built 2021 Time flown and Sold
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Old 08-23-2021, 08:23 AM
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vfrazier vfrazier is offline
Join Date: Jan 2007
Location: Mount Vernon, IN
Posts: 1,392

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.
Vince Frazier
F1 Rocket and F4 Raider components
1-888-F1AIRCRAFT (1-888-312-4727)
RV and Rocket Accessories, Tailwheels, Tools, & More
1-888-8FLYBOY (1-888-835-9269)

F4 Raider - under construction
F1-H Rocket "Crazy Horse" - sold
RV-4 "Chief Pontiac" - sold in 1994, purchased in 2018
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Old 08-24-2021, 07:05 AM
Dayton Murdock's Avatar
Dayton Murdock Dayton Murdock is offline
Join Date: Jan 2005
Location: Carson City NV
Posts: 558

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.
Dayton Murdock
VAF#408 RV4 N359DM O360 C/S, Dual P_Mags, AFS Efis, Trutrak A/P, Leather, Electric trim and flaps, Led lights, Freeflight ADSB and it is painted Red, Flying 1105 hrs 11/28/20

Builder Log
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Old 08-24-2021, 08:14 AM
Jab Jab is offline
Join Date: Apr 2017
Location: Knoxville, TN
Posts: 88

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.
Bought RV-4
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Old 08-24-2021, 12:06 PM
AeroEngineer AeroEngineer is offline
Join Date: Jul 2021
Location: US of A
Posts: 9

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.
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