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RV-3 vs RV-4 ?

L

Larry DeCamp

Well Known Member
I was about to order an RV3-B kit when a respected Harmon Rocket pilot told me the RV4 was better handling over all. He also shared that he had flown the first flight on three RV3's and the original version was better than the 3B because the bellcrank linkage was different. I really respect this pilots opinion, and thought I would get some additional input before making a decision. I really want a light single place ship that is the ultimate fun flying machine . I have a Rose Parrakeet that is pretty cold in the winter !
 
Larry,

I cannot comment on your friends experience, however, here is a link to Randy Levold's site and his flying impressions of the RV-3B:

Flying Impressions

Check out also Steve Sampson's excellent RV-4 G-IKON here:

G-IKON

Above all else, build the plane you want to build.

Good Luck.
 
RV4

For me this was what you Americans call a no brainer. Both airoplanes handle very well but the 4 has that extra seat which gives the oportunity to take a passenger, and in the long run makes it more versatile and easy to sell.;)
 
I agree with WAM120RV. The -4 can be flown without a passenger for its entire life. But that one time you want to take someone up and show them what RV's are all about, at least you can. If you don't have a passenger, you can carry more baggage and go farther instead... The -4 can eat up the miles pretty quick going cross-country.

The -3 won't be any easier or faster to build than the -4, and probably won't be significantly cheaper at the end of the day either.
 
Rose Parrakeet?

How is that Rose Parrakeet?
I saw one for the first time at OSH last summer, and really liked it up close. I've always heard good things about it.

As for the -3 vs -4, I can't comment yet. I just bought a -3A which I haven't flown yet, but the pilots previous to me all liked it. Everything I've read seems to indicate that it is the best of the breed.

I was ok with the single seat, as I already own a 172 to take family or friends around on those rare occasions. But mostly I found (due to my odd working schedule) that I was flying alone about 90% of the time.

Ryan
 
Response to med doc

The Rose is a delightful airplane. It is neutral in roll, meaning if you bank it up to 45 degree, it just stays there and slowly decends. Lands about 35mph. You can count the grass blades. The ailerons are " barn doors" meaning high stick force and some rudder to get a good response.

Thanks for the respone. Single seat works well for me since we have other 2 and 4 place ships available in the family. I will watch for posts regarding the 3A. Congratulations.
 
I'll be very interested in the responses from those who have flown both. I have a 160hp RV3A that is the best flying plane I've ever flown, but it's the only RV I've flown. The fellow I bought it from told me it didn't fly like a -4 but since I had not flown a -4, I didn't go into the differences. I'm kinda thinking about building a two place RV and am leaning toward a -4 if it will fly as good as my -3. Maybe with 180 hp and FP prop, but I need to do some more work with W&B to see how it would work on cross country with my wife and baggage. I don't see how Van's 1500# gross weight would work but have read on the forum that some people are using 1550-1700#. How does that fly? A F1 Rocket would work but I have to draw the line somewhere on the expense and that engine, prop and fuel burn on short flights exceeds it.
 
Problem with a -4 if you largely going to fly it solo is, like an 8, you will be running at a forward CG. Basic aerodynamics, and as stated in the Van's build manual, is an aft CG is "more fun" / "better handling" / "more responsive" / "lighter in pitch".

If you really want << I really want a light single place ship that is the ultimate fun flying machine>> I cannot believe an RV-4 would better an RV-3, unless you went to the extent of moving the CG somehow that it was a solo only machine...

<<The -3 won't be any easier or faster to build than the -4>> Bear in mind the 3 comes with a pre-assembled spar (an option for the RV-4), and you can get RV-3 QB wings (not so for the 4 AFAIK). I would also think the smaller / simpler fuselage would be a little easier to build, although nothing like to the degree of the pre-punched kits.

Andy
 
Don't forget, its easier to justify building a 2 seater after building a one seater than it is the other way around. This only applies if you are married.
 
rph142 said:
Don't forget, its easier to justify building a 2 seater after building a one seater than it is the other way around. This only applies if you are married.
Click to expand...

Yup - It was easy to justify building the one-seater if you're married - and both of you already have a two-seater.....:D
 
Larry

I've gone thru this exercise. I like the idea of a single seat but wanted an
O360 with a fast back. Everyone seems to love the -4 but it needs the CG moved aft. So I'm building a single seat -4 and moving the seat back 4 inches and loosing the back seat. Build light and build what you want.
 
wilddog said:
I'll be very interested in the responses from those who have flown both. I have a 160hp RV3A that is the best flying plane I've ever flown, but it's the only RV I've flown. The fellow I bought it from told me it didn't fly like a -4 but since I had not flown a -4, I didn't go into the differences. I'm kinda thinking about building a two place RV and am leaning toward a -4 if it will fly as good as my -3. Maybe with 180 hp and FP prop, but I need to do some more work with W&B to see how it would work on cross country with my wife and baggage. I don't see how Van's 1500# gross weight would work but have read on the forum that some people are using 1550-1700#. How does that fly? A F1 Rocket would work but I have to draw the line somewhere on the expense and that engine, prop and fuel burn on short flights exceeds it.
Click to expand...

I've flown both, 2000+ in RV3s, 10 or so in an RV4. Lots of side by side comparisons and more than a few tail chases.
The 3 is a little quicker in control response and about on par in speed (assuming equal build, hp and prop). Climb is of course better in the 3 because of the weight difference. The deal breaker is a C/S prop. Add a C/S prop to either one and the other one will be more responsive. I was surprised at the difference. If you are comming from a GA aircraft either one will light your fire.
 
re: more info on the C/S prop

RV3 Pilot said:
I've flown both, 2000+ in RV3s, 10 or so in an RV4. Lots of side by side comparisons and more than a few tail chases.
The 3 is a little quicker in control response and about on par in speed (assuming equal build, hp and prop). Climb is of course better in the 3 because of the weight difference. The deal breaker is a C/S prop. Add a C/S prop to either one and the other one will be more responsive. I was surprised at the difference. If you are comming from a GA aircraft either one will light your fire.
Click to expand...

Hi,

Just wondering what causes the negative impact on responsiveness; hope you can elaborate a bit.

Thanks!

Brian
 
WEIGHT!

A C/S prop adds considerable weight on the nose. The smaller/lighter the airplane the greater the percentage of weight increase.
 
Mel said:
A C/S prop adds considerable weight on the nose. The smaller/lighter the airplane the greater the percentage of weight increase.
Click to expand...
Not if you consider a Whirl Wind 151-H... 29 lbs for the entire assembly, just about the same weight as a wood prop when you include the extension. More info for those interested here.
 
Well, lets use some race car technology...

brianw said:
Hi,

Just wondering what causes the negative impact on responsiveness; hope you can elaborate a bit.

Thanks!

Brian
Click to expand...

If you hold a barbell in the middle and start rotating it either to the left or right, trying to stop it is difficult, with the weight concentrated on the ends.

Mount the weights in the center of the rod and hold outside of the weights and do the same exercise and you'll find much quicker response....the same reason F-1 and Indy cars are mid-engined and the most responsive vehicles in the world....the ends are light and the weight concentrated toward the center. It reduces what I believe is called the "Polar moment of inertia".

Putting a heavy CS prop on a small, light airplane like a -3 or -4 is pretty close to having the barbell weights on the ends:)

Best,
 
Depending on the model RV-3 (original/A or B) and the pilot weight combo and how much you have in the baggage, as you burn fuel, your CG will shift aft. Having more weight on the nose may counterbalance the trim you will need to dial in as the fuselage tank empties.
 
RV-3 CG Range

MedFlightDoc said:
Depending on the model RV-3 (original/A or B) and the pilot weight combo and how much you have in the baggage, as you burn fuel, your CG will shift aft. Having more weight on the nose may counterbalance the trim you will need to dial in as the fuselage tank empties.
Click to expand...

The RV-3 with wing tanks holds 30 USG of fuel which weighs 180lbs.

Using all of this fuel moves the C of G back by 0.73". The RV-3 has a C of G range from 59.72" aft of datum to 64.58" aft of datum. One has to be more careful of the weight in the baggage compartment as this has more effect on the C of G because of the greater moment arm at this station. Putting 50lbs of baggage in the baggage compartment moves the C of G back by 2.32" or 48% of the available range.
 
Gyroscopic Effect

It's not just the added weight. Wood props have a much lower gyroscopic effect which gives a more responsive aircraft.
 
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