Van's over-engineering compared to certified aircraft

[KatanaPilot]

Sure they do - Van's specs. Don't assume that because it's not published in the federal register that it's not a design specification.

Agreed. What I should have said was that I can't determine what FAA or EASA spec(s) any of the RV series meet, other than the LSA RV-12.

You are judging all RVs by a part 23 design standard, but not all - in fact most - were designed to that standard.

And we know that how? At least with a certified airplane you can be pretty confident that not only was it designed to that standard, it was tested and proven.

Conversely, I might say that DA40 is under engineered, since it's not stressed for aerobatics, has relatively high stick forces, low roll/pitch rates, and excessive takeoff and landing distances compared to some RV models.

Sure, different airplanes for very different missions. The 9, 10 and 12 weren't designed for aerobatics either. I'd still prefer to be in an accident in ANY Diamond versus ANY RV.

Both are fine airplanes and we can infer that they both have proven to measure up to their design specifications. But the DA40 fails to measure up to the same specs as an RV-4 (for example), and the -4 wouldn't meet part 23.

Hardly a reasonable comparison. Maybe a better one would be a 10 and an SR22?

Yes, I know my RV-7 and under construction 10 will outperform my DA20 and 40 in handling qualities, speed and runway performance but I am not willing to accept that RV's are over-engineered in comparison.

[ChiefPilot]

Originally Posted by KatanaPilot

And we know that how? At least with a certified airplane you can be pretty confident that not only was it designed to that standard, it was tested and proven.

My error. I meant to state the opposite actually of what I wrote - the "not" that I omitted originally is important :-)

You are judging all RVs by a part 23 design standard, but some - in fact most - were not designed to that standard.

I think we're on the same page. "Over engineering" is used in a vague way and having spent my previous career in engineering I'm perhaps a bit sensitive when terms like that get thrown about :-)

[cajunwings]

Just my $.02 after 40+ years of maintaining and repairing light aircraft. The RV line is well engineered for the intended mission and price point. There?s no magic, they are light and clean with a good power to weight ratio. The lightness comes from using just enough metal and fiberglass to get the job done so I wouldn?t consider the RVs as durable as a similar certified aircraft. A good example of this is the landing gear. If it was built like a Cherokee it would perform like one. We just accept compromises to get the fabulous performance for the dollar that we all love so much.

Don Broussard A&P IA ATP
RV9 Rebuild in Progress
57 Pacer

[Reformed SeaSnake]

I'll open by saying I'm not too big a fan of the term "over-engineering". It implies the design engineer did not have a clear reason for the design specifications; like using .032 everywhere .025 meets spec just because "a bit thicker has to be better right?" The problem with that is that design is a series of compromises and making any part of any aircraft "beefier" than it needs to be based on the design criteria would adversely affect some other characteristic of the aircraft (cost, useful load, handling, etc).

I think it is very likely that the designer considered the variability in the workmanship of the builders, construction materials, and the intended use of the aircraft as they determined the design specs and safety margins. One good example is the nose gear. Cessna clearly intended the 172 to be flown by low-time pilots and designed a nose gear that would take a least a bit more abuse than an "A" series RV will. The nose gear RVs are just as clearly not intended to be the first plane you fly. It is just as likely that Vans designers built more-than-customary safety margins in other aspects of the design to account for builders with less skill than the average Cessna worker.

[meloosifah]

If you want over-engineered, look at a Navion. But then, it is thought that it was designed to land on a carrier (and did) so maybe not over-engineered after all. I would never put an -A model Vans aircraft through what I have put a tripacer through. If Vans is over-engineered then a tripacer is over-over-engineered.

They are what they are - total performance. But I would argue that they are just enough to accomplish the mission. We know that it is possible to rip the wings and tails off these things. How many 172s out of all the thousands flying have ripped their tails off in flight over the past 5 or 6 years (or however long it?s been since the -7 driver went down)?

Saying they are over-engineered May lead some zealous and foolish pilot to over-load or over-fly their over-engineered plane.

[paul330]

This is like the argument I hear all the time that Boeings are built "stronger" than Airbuses. It's total BS. No designer builds an aeroplane (especially a commercial one) any stronger than it need to be to be able to do the job and meet the appropriate legal design criteria. A heavier or beefier Boeing is going to have a commercial disadvantage when it comes to payload/range capability.

It comes down to appearances. Having flown both commercially I can compare. Boeings have bigger, chunkier switches. They have control yokes rather than side sticks. Big, moving thrust levers rather than small fixed ones etc etc. The whole impression is "beefier" - American design against European. Nothing to do with being stronger or over-engineered.

[Sam Buchanan]

It would be kinda silly for me, as a non-engineer, to claim anything is over or under engineered....

[BrianDC]

Personally I would prefer that they at least slightly over-engineer their design vs under-engineered!

I'm sure there are examples of perfectly built RV aircraft but would much prefer some "safety margin" and expectations that some builders take longer to get to the top of the learning curve. Based on what I have seen on some of Vic's slides I would subjectively say that our aircraft are at least slightly forgiving. That doesn't mean you ignore bad rivets or skip bolts in your build, counting on this margin.

[Captain Avgas]

I love flying my RV7A...but I?d rather crash a Cessna.

[KatanaPilot]

Originally Posted by paul330

This is like the argument I hear all the time that Boeings are built "stronger" than Airbuses. It's total BS. No designer builds an aeroplane (especially a commercial one) any stronger than it need to be to be able to do the job and meet the appropriate legal design criteria. A heavier or beefier Boeing is going to have a commercial disadvantage when it comes to payload/range capability.

It comes down to appearances. Having flown both commercially I can compare. Boeings have bigger, chunkier switches. They have control yokes rather than side sticks. Big, moving thrust levers rather than small fixed ones etc etc. The whole impression is "beefier" - American design against European. Nothing to do with being stronger or over-engineered.

Hate to start an off-topic Boeing versus Airbus war, but as a former Boeing engineer and long time Boeing pilot, I'm going to push back a bit.

China Air 006, 747SP, pulled about 5 G's during a recovery from loss of control at 41,000 feet. Aircraft was damaged, some injuries occurred, but the airplane stayed (mostly) intact and landed safely. As you know, transport category design load factor is 2.5G's positive, with ultimate load limit of 3.8G's. I'm not aware of any early Airbus models that have "accomplished" anything similar.

Of course, the FBW Airbus models should never depart controlled flight and can't pull more than 2.5G's in normal law. So I suspect (but have no proof), that Airbus can design their FBW models with a little less margin. Whether they do or not - I really don't know.

Boeing's implementation of Fly By Wire incorporates soft and hard limits, giving pilots the ability to pull 2.6 G's (or more) if needed and aerodynamically available.