VansAirForceForums  
Home > VansAirForceForums

-POSTING RULES
-Advertise in here!
- Today's Posts | Insert Pics

Keep VAF Going
Donate methods

Point your
camera app here
to donate fast.


Go Back   VAF Forums > Model Specific > RV-10
Register FAQ Members List Calendar Search Today's Posts Mark Forums Read

Reply
 
Thread Tools Search this Thread Display Modes
  #21  
Old 03-10-2021, 11:53 PM
rongawer rongawer is offline
 
Join Date: Dec 2007
Location: Brentwood, CA
Posts: 730
Default

Quote:
Originally Posted by BobTurner View Post
I could be wrong here, but my impression is that all or most all of these incidents are basic pilot error: the pilot took off with one or both latch pins not engaged, and one or both red idiot (door open) lights on. Its a human factors thing: we taxi in hot wx with the door ajar, and get used to seeing the lights on. I wonder if a better warning system - Iím thinking, tie the red lights thru a tach or airspeed switch, then to something like a gear warning horn that is so obnoxious it canít be ignored - would be an easy fix to 90% of the problem. It wouldnít fix a passenger actually opening the door in flight, but would fix most other things.
Iím thinking along this line Bob. The G3X has the ability to do canopy/door open alerts based on engine RPM; combined with 180 latches probably solves most of the issues, but what about taxiing with door unlatched, maybe even held partially closed, on a gusty day?

Any cure that relies on human intervention is subject to error.
__________________
Ron Gawer

- RV10, N762G, Build in progress.
- Several others that are now just great memories for me.
Reply With Quote
  #22  
Old 03-11-2021, 11:19 AM
kearney kearney is offline
 
Join Date: Dec 2006
Location: Canmore, Alberta, Canada
Posts: 49
Default

Quote:
Originally Posted by rongawer View Post
The doors on the da42/62 are similar to the da-40 rear door, but also similar to the Trinidad.

While putting your hope in following a checklist and looking for warning lights are good things to help prevent the event; itís an administrative cure. Much like power plant safety, engineered solutions are the best ones and then rely on administrative and personal protective measures as a secondary step.

If Vans concurs that the cabin top structure is inadequate to handle the shear force of a door open in flight and that the door is designed to liberate as a protective measure, then Iíll accept that. However, to colloquially state that ďno hinge on earth will keep it attachedĒ lacks engineered basis. I assure you, I can design a cabin cover and hinge to do the job. It just may not be cost effective. I need to know more about the design basis of the cabin cover first.
Okay, I am not an engineer but it seems intuitively obvious that a door installed per plans will fail at the hinge / fiberglass interface (or the hinge) given the twisting/shear forces on an open door in flight. My comment had *some* hyperbole but not much.

If you move the hinge then that is a different. I had a PA28 for 19 years and had to fix a partially open door in flight on more than one occasion. It was no bid deal. Hinges on the top of the door are a completely different kettle of fish.
__________________
Les

RV10 C-GCWZ Sold and now vacationing in Tulsa
RV10 C-GROK Flying
RV10 # 3 - under construction

*** Dues Paid ***
Reply With Quote
  #23  
Old 03-11-2021, 12:19 PM
rocketman1988 rocketman1988 is offline
 
Join Date: Jun 2010
Location: Sunman, IN
Posts: 2,432
Default True

"...Okay, I am not an engineer but it seems intuitively obvious that a door installed per plans will fail at the hinge / fiberglass interface (or the hinge) given the twisting/shear forces on an open door in flight..."

True, however, the designer likely assumed that the door would be closed during flight...If that was the initial assumption, then the current door/hinge assembly design is adequate.

Is it a realistic assumption that the door would be closed during flight? Likely.

Could the door physically come open in flight if both pins were engaged? Not likely.

Now add the human element. This is where it gets harder.

Could someone unintentionally miss engaging one of the pins? Absolutely.

So, now we seek a solution. Re-engineer the cabin top structure for a forward hinge or add a light system and safety latch to alert the human...As no one would intentionally fly with the door open, it would seem that a safety reminder light, and an additional latch would be sufficient to mitigate the risk...without a complete re design of the cabin top and door assemblies.

It will always be a compromise but one thing is for sure, when a human is involved, anything can happen...
__________________
Bob
Aerospace Engineer '88

RV-10
Phase I COMPLETE!

Dues+ Paid 2020,...Thanks DR+
Reply With Quote
  #24  
Old 03-12-2021, 12:53 PM
flion's Avatar
flion flion is offline
 
Join Date: Dec 2007
Location: Flagstaff, AZ
Posts: 2,688
Default

Quote:
Originally Posted by rocketman1988 View Post
Could someone unintentionally miss engaging one of the pins? Absolutely.
I still don't get how this can happen. My top and doors are the pink ones and the doors are assembled per the kit instructions save for the flush handles. No special stiffening and it takes significant force to twist the doors enough to latch with only one pin. Missing both pins is easy, though, I suppose.

After seeing the bond come apart in the OP's photos, I realize that it is merely a surface-to-surface bond, nothing mechanical or truly laminated about it. I am thinking of drilling around the perimeter and refilling the holes with flox to make some glass rivets to strengthen the bond on my kit. It wouldn't keep the door on the aircraft but it might keep a door from coming apart due to age or recurring stress of flight.
__________________
Patrick Kelley - Flagstaff, AZ
RV-6A N156PK - Flying too much to paint
RV-10 14MX(reserved) - Fuselage on gear
http://www.mykitlog.com/flion/
EAA Technical Counselor #5357
Reply With Quote
  #25  
Old 03-12-2021, 01:21 PM
Carl Froehlich's Avatar
Carl Froehlich Carl Froehlich is offline
 
Join Date: Dec 2007
Location: Dogwood Airpark (VA42)
Posts: 2,943
Default

Quote:
Originally Posted by rongawer View Post
Iím thinking along this line Bob. The G3X has the ability to do canopy/door open alerts based on engine RPM; combined with 180 latches probably solves most of the issues, but what about taxiing with door unlatched, maybe even held partially closed, on a gusty day?

Any cure that relies on human intervention is subject to error.
After a Rhode Island Air National Guard prop blast ripped off my RV-10 pilot door as I was fueling, I created the golden rule:
- Unless the plane is in the hangar, someone is getting in or out, the doors are always shut and locked.

That mean no engine start, no door ajar for taxi, no leaving the door open to fuel, etc.

When not locked these doors are fragile. Even with the door shut but not locked there is risk - as in my case the prop blast bounced the door enough to get under it and away it went.

The door hinges snapped like toothpicks but the hinges (halfs) remained attached to the cabin top and door. No damage at all. The hinge attach screws where installed with #10 tinnermans - as where the other door hardware.

The upside for me was the door did a perfect flip over the canopy, an edge hit the right wing and put a dent in the skin, then landed in the grass. The door had a corner dinged up but other than that is was good to go. I got a couple of hinges from Vanís and flew home.

The Air National Guard eventually paid my claim and although the wing was repairable I built a new wing. The door required some fiberglass work and paint.

So keep the doors shut and locked!

Carl
Reply With Quote
  #26  
Old 03-12-2021, 01:52 PM
David Paule David Paule is offline
 
Join Date: Dec 2009
Location: Boulder, CO
Posts: 4,759
Default

Quote:
Originally Posted by flion View Post
....After seeing the bond come apart in the OP's photos, I realize that it is merely a surface-to-surface bond, nothing mechanical or truly laminated about it. I am thinking of drilling around the perimeter and refilling the holes with flox to make some glass rivets to strengthen the bond on my kit. It wouldn't keep the door on the aircraft but it might keep a door from coming apart due to age or recurring stress of flight.

There's a considerable difference between a bond that has properly-prepared surfaces and one that does not. The doors in the OP were clearly not properly prepared. If prepared according to the plans and Chapter 5, this particular mode of failure is not critical.

"Glass rivets," or more properly, epoxy rivets, are not inherently strong. First, epoxy itself is a lot weaker than the glass/epoxy laminate or even a cotton/epoxy blend, which is what's suggested above. Second, every hole reduces the bond area available for strength. Follow the plans here.

Dave
Reply With Quote
  #27  
Old 03-13-2021, 12:45 PM
flion's Avatar
flion flion is offline
 
Join Date: Dec 2007
Location: Flagstaff, AZ
Posts: 2,688
Default

Quote:
Originally Posted by David Paule View Post
There's a considerable difference between a bond that has properly-prepared surfaces and one that does not. The doors in the OP were clearly not properly prepared. If prepared according to the plans and Chapter 5, this particular mode of failure is not critical.

"Glass rivets," or more properly, epoxy rivets, are not inherently strong. First, epoxy itself is a lot weaker than the glass/epoxy laminate or even a cotton/epoxy blend, which is what's suggested above. Second, every hole reduces the bond area available for strength. Follow the plans here.

Dave
What you say is true but there is also a difference between a laminating bond on 'green' expoxy and one on fully cured epoxy, even if the surface was prepared with peel ply or abrasive surface preparation. Also, there is a difference between epoxy rivets and glass rivets. Flox will stabilize the epoxy quite a bit. Better still would be to put some glass fiber or carbon tow through the hole before the epoxy.

Honestly, I'm not that worried about my doors' bonds because there's not much flex and so little opportunity for the epoxy to craze and delaminate. But the apparent flexibility of other builders' doors does have me thinking a bit.
__________________
Patrick Kelley - Flagstaff, AZ
RV-6A N156PK - Flying too much to paint
RV-10 14MX(reserved) - Fuselage on gear
http://www.mykitlog.com/flion/
EAA Technical Counselor #5357
Reply With Quote
  #28  
Old 03-13-2021, 07:09 PM
Bill Boyd's Avatar
Bill Boyd Bill Boyd is offline
 
Join Date: Sep 2006
Location: Landing field "12VA"
Posts: 1,637
Default

A little O.T., but when I rode as safety pilot in a friend's -10 today, I noticed that his door bowed enough in flight to see daylight beyond the McMaster seal at the upper forward corner of the door. This was true of both doors. He has the Plane-Around latch and did a god job fitting his doors. A little investigation with the back of my hand confirmed that air was leaking out of the door opening in this low pressure/high velocity flow region of the cabin top.

When I go up again I will look for the same phenomenon in my -10. I used a different width of McMaster seal and was careful to angle my pins and locate the holes so that the latches pulled the door downward as well as inward as the pins seated in the door frame. My door skin might be under more tension top to bottom than my buddy's doors. I'll report back. Interested to hear if this is a common finding in the field.
__________________
Bill Boyd

Hop-Along Aerodrome (12VA)
RV-6A - N30YD - Built '98 / sold '20
RV-10 - N130YD - Phase 1 flying

Donation constant, K, = 1/woke censorship; not looking good this year.
Reply With Quote
  #29  
Old 03-14-2021, 08:40 AM
rocketman1988 rocketman1988 is offline
 
Join Date: Jun 2010
Location: Sunman, IN
Posts: 2,432
Default doors

I have not notice any air leaks around my doors.

Plane around latch and McMaster seal, 1/4" flange and 3/8" bulb...
__________________
Bob
Aerospace Engineer '88

RV-10
Phase I COMPLETE!

Dues+ Paid 2020,...Thanks DR+
Reply With Quote
  #30  
Old 03-14-2021, 11:19 AM
lr172 lr172 is offline
 
Join Date: Oct 2013
Location: Schaumburg, IL
Posts: 5,987
Default

Quote:
Originally Posted by rocketman1988 View Post
I have not notice any air leaks around my doors.

Plane around latch and McMaster seal, 1/4" flange and 3/8" bulb...
Same here. Mine is very rigid when locked and I get ZERO draft through the door seal area and I have the small 7/32 bulb. I suspect this could be variable based upon how the door parts are glued up or how the pin holes are located.

Larry
__________________
N64LR - RV-6A / IO-320, Flying as of 8/2015
N11LR - RV-10, Flying as of 12/2019
Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -6. The time now is 11:47 PM.


The VAFForums come to you courtesy Delta Romeo, LLC. By viewing and participating in them you agree to build your plane using standardized methods and practices and to fly it safely and in accordance with the laws governing the country you are located in.