Here is the real story
rvbuilder2002 said:
I don't think Van's ever publishes Estimated Empty weights. They publish the actual empty weight of their particular prototype/demo airplane of any given model. Builders of that model can then evaluate the way it is equiped and make estimates of what they think their own airplane will weight when using the equipment they are choosing.
That is not true. They are based on a prototype, but I think you missed the points. You can call it a "Spec empty weight" or a suggested, recommend, target, actual, estimated, listed or calculated empty weight. The reality is RV's weigh what they weigh. READ ON.
One,
Vans prototype's (or estimates) are at the low end of RV min or ACTUAL empty weights of most completed RV's. You'll also see a "RANGE" of empty weights for most RV models. This range is based on estimates or calculation from a prototype, but you are correct, it's not a total guess. Its a little actual and a little calculated. For example: I don't think Van has a wood prop-ed O-320 RV-7 or RV-8, but they estimated a MIN from their other prototype's. Van may update or revise their inital "spec" weights from builder data as it comes in, but from what I see they don't. They build a LIGHT prototype and do a little math to get reasonable "target" weights.
My main point,
most builders have higher empty weights than what Van publishes, wheather based on an actual prototype or calculated estimate. Van's prototypes have notoriously been very basic in the past. Only in the last 10 years has Van splurged on C/S props and more than airspeed and altitude inst panels. You see one light tail strobes, no primer under exterior paint, bare metal no internal primer, basic, basic, panels and so on. Trust me Van was known as the flying Dutch man, meaning cheap. He always has been a minimalist. However he has recognized that people are people and they are going to get the biggest engine they can, constant speed prop and fill every square inch of the panel and cockpit with goodies and leather seats. Not to mention auto pilots and heated pitot (for Gosh knows what reason, planning on flying in ice in your VFR RV?).
Any way Van has become more realistic or at least gave the people what they wanted, more gross and of course a higher empty to match. It does not make them better planes. Fly a super light RV-4 or RV-6 with a 320/wood prop, day VFR and you will know what I mean.
I do agree Vans data is based on real info, not guesses, and the weights are achievable with some care.
I have a data base with 120 RV's. I get data from Van's news letter from the completed RV's and Dan the man's web site. Here's a summary if you care.
...........BUILDER REPORTED EMPTY WEIGHT'S
Total.....Model....subtotal......min.......max.......avg*
11..........RV-4......11...........874......1107.......980
.............RV-6......28...........980......1244.......1058
50..........RV-6A....22............990.....1195.......1105
.............RV-7......15..........1011......1141.......1073
25..........RV-7A....10..........1020......1134.......1092
.............RV-8......15..........1035......1178.......1102
22..........RV-8A.....7...........1032......1165.......1101
7............RV-9A....7...........1034.......1168......1086
*Simple average
Note: above data does not include "auto engines", which tend to be heavy. I don't have much data on auto engine RV's since there are not as many and they tend not to advertise their empty weight, but they seem to average about 100 to 60 lbs more than a typical RV with a Lyc 320 or 360 (160HP/180HP).
Now Vans empty weight "numbers":
.............VAN'S DATA FOR EMPTY WEIGHT
.............Min.......Max....Vans Avg...Blder Avg....Delta
RV-4.......905.........913.......909........980.........+71
RV-6.......965.......1018.......992.......1058.........+66
RV-6A.....985.......1038.......1012......1105........+93
RV-7.......1061.....1114.......1088......1073.........-15
RV-7A.....1077.....1130........1104.....1092.........-11
RV-8.......1067.....1120........1094.....1102..........+8
RV-8A.....1067.....1120........1094.....1101..........+8
RV-9A.....1028......1075.......1052.....1086.........+35
It's crude from a statistical standpoint, but I'm not going to get into mean, std deviation and so on, but I did that as well. The data is representative of a good cross section of RV's and speaks and simple averages illustrate nicely real or actual RV weights. I can assure you there's a pattern in the data, builders build heavy RV's (heavier than Van's prototypes at least), BUT THEY DON'T HAVE TO.
There are many builders that have built RV's below Van's listed empty weight, in several cases by a large margin!
It CAN BE DONE. The winner's of light weight RV's are:
RV-4 @ 874 lb's (32 lb under)
RV-7 @ 1011 lb's (50 lb under)
RV-7A @ 1020 lb's (57 lb under)
RV-8 @1035 lb's (32 lb under)
RV-8A @ 1032 lb's (35 lb under)
No RV-6(A)'s or RV-9(A)'s where under Van's min or target empty weight in my data.
RV-6 & RV-6A's, tend to be over weight since van's RV-6 "listed" empty is only 965 lbs, the RV-6A lists 985 lbs, 20 lbs more than the taildragger (I think that is an **estimate). It is hard to beat. Van list only single empty weights for the RV-6(A), min/max range. If you add the 53 lb empty weight spread or "range" that's listed for the RV-7's and RV-8's, you get 1018/1038 lbs. Many RV-6(A)'s are still over this higher weight. The lightest RV-6A was within 5 lbs of Van's spec empty 985 lbs. The lightest RV-6 was 980 lbs, 15 lbs over the min. Congrats to that nameless builder. Van's prototype is the winner of the light weight RV-6 award. (** Trikes tend to be about 10 lbs more with everything else being equal, actual weight.)
RV-9A's are not too bad, but no one has beat Van's prototype or spec MIN empty at 1028 lbs. The lightest builder RV-9A I found was 1034 lb's, 6 lb over the min but under the 1057 lb max. Another Congrats and well done back slap.
THE FAT ONES
The first fat RV award goes to a RV-6 at 1244 lb empty, well over Vans "target" empty by 279 lbs!!
In general RV-6(A)'s are well over Van's spec by a good amount. The low 1,600 lb gross of the RV-6(A) drives the low empty. The RV-4 has even less spec weights, 1,500 gross and 905/913 lb empty, so it's in the same boat, but the RV-4's tend to not suffer from empty weight bloat as bad as the RV-6 does. Why Van list a 905-913 lb weight for the RV-4 I don't know? (anyone) I suspect its an actual weight but also with a O320/fixed wood prop. Most people don't use that much, but its an awesome combo and very light.
The next fat offender is a RV-9A, which exceed Van's max empty spec target of 1075 lbs by 93 lbs, w/ a O320 and Hartzell. Sure the prop is heavier, but it does not account for all of the 93 lbs. RV9A'ers, be careful with those 360's and Hartzells, great on a RV-7 but not so good for a RV-9A. Van does not pull his weight's out his ear. They are critical to good overall safety and performance. (Lecture hat off, stepping of soap box, for now.
)
The runner up in the fat contest are RV-8(A)'s overall. They tend to get fat in the hands of builders, several where in the 45-58 lbs over Van's "max-suggest-estimated-actual-target" empty weight category.
However the average is only 8 lbs over, and some builders have managed to get their empty weight 30 lbs below Van's spec empty wt. Good for them. MY PET PEEVE, Keep it light.