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  #1  
Old 09-03-2019, 02:34 PM
Bigspoon17 Bigspoon17 is offline
 
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Location: Pensacola, FL
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Default Van's over-engineering compared to certified aircraft

I was reading through some older threads last night about how the RVs are significantly over-engineered when compared to other certified aircraft. Vic made reference specifically to a comparison between an RV and a Cessna. I'd be curious to know, does anyone have pictures, drawings, etc. that might show to what degree these airplanes are over-engineered?
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  #2  
Old 09-03-2019, 02:51 PM
Robin8er Robin8er is offline
 
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I don't have a drawing, but I've looked inside some airplanes structures and said "thats the wing spar?!?!?!" Or "that's the engine mount!?!?!?". Same for hinges, brackets etc.

Stuff on RV's does seem to be beefier that alot of certified stuff.
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  #3  
Old 09-03-2019, 03:04 PM
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ChiefPilot ChiefPilot is offline
 
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Quote:
Originally Posted by Bigspoon17 View Post
I was reading through some older threads last night about how the RVs are significantly over-engineered when compared to other certified aircraft. Vic made reference specifically to a comparison between an RV and a Cessna. I'd be curious to know, does anyone have pictures, drawings, etc. that might show to what degree these airplanes are over-engineered?
I don't know that they are as over-engineered as some would think. There has been mention of the spar and motor mounts, for example, but comparing those on an RV to a C-172 is not really appropriate since the typical two seat RV is stressed for +6/-3G while the C-172 is a utility category aircraft only. Moreover, the C-172's wing spar isn't carrying the load in the same way since it is strut-braced and not a cantilevered design.

The only accurate way to know if something is "over-engineered", as used in this context, is to understand the design specifications and then compare them to the actual design. If the design spec says +6/-3 but the design will handle +12/-6, then saying it's over-engineered is probably fair. But to say that one design implementation (an RV) is over-engineered to another design implementation (C-172) is specious at best.
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  #4  
Old 09-03-2019, 03:14 PM
Bigspoon17 Bigspoon17 is offline
 
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Quote:
Originally Posted by Robin8er View Post
I don't have a drawing, but I've looked inside some airplanes structures and said "thats the wing spar?!?!?!" Or "that's the engine mount!?!?!?". Same for hinges, brackets etc.

Stuff on RV's does seem to be beefier that alot of certified stuff.
This is the kind of stuff I was referring to, hoping someone might have some pictures. I wonder if the beefiness of the RVs is because of the aerobatic capabilities or just generally more solid construction?
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  #5  
Old 09-03-2019, 03:18 PM
Bigspoon17 Bigspoon17 is offline
 
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Originally Posted by ChiefPilot View Post
I don't know that they are as over-engineered as some would think. There has been mention of the spar and motor mounts, for example, but comparing those on an RV to a C-172 is not really appropriate since the typical two seat RV is stressed for +6/-3G while the C-172 is a utility category aircraft only. Moreover, the C-172's wing spar isn't carrying the load in the same way since it is strut-braced and not a cantilevered design.

The only accurate way to know if something is "over-engineered", as used in this context, is to understand the design specifications and then compare them to the actual design. If the design spec says +6/-3 but the design will handle +12/-6, then saying it's over-engineered is probably fair. But to say that one design implementation (an RV) is over-engineered to another design implementation (C-172) is specious at best.
I can appreciate this, and I did contemplate prefacing my post with an apples-to-oranges disclaimer. I have never taken the time to really look into the construction of a 172 (or Archer, or whatever) because before I started building my 14 I really didn't care. Now that I know what the inside of mine looks like it makes me curious about others!
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  #6  
Old 09-03-2019, 04:25 PM
KatanaPilot KatanaPilot is offline
 
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Quote:
Originally Posted by Bigspoon17 View Post
I was reading through some older threads last night about how the RVs are significantly over-engineered when compared to other certified aircraft. Vic made reference specifically to a comparison between an RV and a Cessna. I'd be curious to know, does anyone have pictures, drawings, etc. that might show to what degree these airplanes are over-engineered?
My Diamond DA40 had a 26G "cocoon" for the passengers and crew, plus airbag seatbelts. The fuel tanks were welded aluminum placed between two beefy composite wing spars. My 1650 pound DA20 had a nose gear design more like the 2050 pound RV-14A.

Accident data would seem to indicate that these Part 23, factory built airplanes are a lot more "over-engineered" than the non-certified, garage-built RV's.

I for one am not convinced that the RV's are over-engineered compared to certified planes.
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  #7  
Old 09-03-2019, 04:34 PM
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ChiefPilot ChiefPilot is offline
 
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Originally Posted by KatanaPilot View Post
My Diamond DA40 had a 26G "cocoon" for the passengers and crew, plus airbag seatbelts. The fuel tanks were welded aluminum placed between two beefy composite wing spars. My 1650 pound DA20 had a nose gear design more like the 2050 pound RV-14A.

Accident data would seem to indicate that these Part 23, factory built airplanes are a lot more "over-engineered" than the non-certified, garage-built RV's.

I for one am not convinced that the RV's are over-engineered compared to certified planes.
I take it you've reviewed the design specifications for both then in order to make this comparison? And what's the max load factor for a DA40 again?
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  #8  
Old 09-03-2019, 04:37 PM
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mfleming mfleming is online now
 
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I've heard people exclaim about Van's being overbuilt ...but it's just not true IMHO.

My -7 is NOT over engineered, far from it. It's a great aircraft but the total performance comes from the light weight design. Some Beechcraft's may be considered over designed...they're built like a tank.
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Last edited by mfleming : 09-03-2019 at 04:40 PM.
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  #9  
Old 09-03-2019, 04:43 PM
KatanaPilot KatanaPilot is offline
 
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Originally Posted by ChiefPilot View Post
I take it you've reviewed the design specifications for both then in order to make this comparison? And what's the max load factor for a DA40 again?
Kind of difficult to do. I do know that all of the Diamond's meet Part 23. No idea if any of the RV's meet any spec.

This link provides a bit better perspective

https://www.diamondaircraft.com/en/private-pilots/safety/

Other than a couple of drop test videos, not much from Van's as to their design criteria.

The Diamonds are normal/utility category, same as some of the Van's designs.

My issue is with blanket salesman-like comments with very little data to back them up.
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Krea Ellis

Locust Grove, GA
DA20-A1 "Princess Amelia" - gone home to Amelia Island
RV-7A Phase 2 (Honored to be Van's "Miss July" 2021)
RV-10ER officially an airplane as of 4/5/22!
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  #10  
Old 09-03-2019, 04:58 PM
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ChiefPilot ChiefPilot is offline
 
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Originally Posted by KatanaPilot View Post
No idea if any of the RV's meet any spec.
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.

Quote:
Originally Posted by KatanaPilot View Post
My issue is with blanket salesman-like comments with very little data to back them up.
I agree, which is why I take issue with blanket salesman-like comments with very little data to back them up. For example:
Quote:
Accident data would seem to indicate that these Part 23, factory built airplanes are a lot more "over-engineered" than the non-certified, garage-built RV's.
You are judging all RVs by a part 23 design standard, but not all - in fact most - were designed to that standard. 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.

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.
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