Tip-up lift in flight

[Radioflyer]

Flying in cold weather recently, my passenger complained of a freezing cold wind on her hands. Reaching over to her side I could confirm the breeze, yet the vent was closed. During a later flight with proper lighting orientation with the sun, I noticed that the canopy was lifting about 1/16" off the longerons, especially towards the forward portion. (Both locks engaged as normal.) Source of cold breeze confirmed!
On the ground, the canopy fits/sits perfectly so this lift induced gap has taken me by surprise. Question, has anyone else noticed this lift effect? I suppose I could just add a little more compressible sealing material to block the wind ingress.

 

[jfogarty]

I have not noticed lifting. I have placed compressible sealing material to the canopy frame arms. Once in place it has not moved.
Also, I plug the air vents during the winter months.

 

[rvbuilder2002]

Flying in cold weather recently, my passenger complained of a freezing cold wind on her hands. Reaching over to her side I could confirm the breeze, yet the vent was closed. During a later flight with proper lighting orientation with the sun, I noticed that the canopy was lifting about 1/16" off the longerons, especially towards the forward portion. (Both locks engaged as normal.) Source of cold breeze confirmed!
On the ground, the canopy fits/sits perfectly so this lift induced gap has taken me by surprise. Question, has anyone else noticed this lift effect? I suppose I could just add a little more compressible sealing material to block the wind ingress.

The shape of the canopy induces a lifting force just like a wing does.
That is why it will lift open in flight if it becomes unlatched.
Use a seal that will adjust to a changing gap.

 

[Radioflyer]

The shape of the canopy induces a lifting force just like a wing does.
That is why it will lift open in flight if it becomes unlatched.
Use a seal that will adjust to a changing gap.

Sure, I understand the forces, but I was wondering if the opening gap was typical. I just wasn't expecting such "slop" (in hinges / locks / general structure) when the canopy otherwise seems nice, tightly fitted, and closed.

 

[ronrapp]

Sure, I understand the forces, but I was wondering if the opening gap was typical. I just wasn't expecting such "slop" (in hinges / locks / general structure) when the canopy otherwise seems nice, tightly fitted, and closed.

My RV6 does the same thing.

 

[D-Dubya]

So does my RV-7...at least on the section forward of the panel.

 

[Snowflake]

My -6 does this as well, I get about 1/4" in flight. Not great if you encounter rain.

 

[Radioflyer]

Ok, glad (sort of) that this canopy gap in-flight doesn't seem unusual. My current seals are the black EPDM rubber D profile. I suppose I can try replacing with larger dimension version of the stuff. However, I'm going to explore a side-wise "V" profile that I saw once somewhere. The open end of the V would face outward such that the breeze that wants to come into the cabin would expand and seal the gap even better. All in the hope of improving my lady friend relations.

 

[BillL]

Ok, glad (sort of) that this canopy gap in-flight doesn't seem unusual. My current seals are the black EPDM rubber D profile. I suppose I can try replacing with larger dimension version of the stuff. However, I'm going to explore a side-wise "V" profile that I saw once somewhere. The open end of the V would face outward such that the breeze that wants to come into the cabin would expand and seal the gap even better. All in the hope of improving my lady friend relations.

My tipper does not lift with speed. I believe that the reinforcement kit was to prevent this. You should look at all the places that could flex and allow lift. Photos would be good. Even getting under the panel with a dowel and pushing up to see (outside observer too) what is moving. This does not seem right. It could be the entire sub panel, I reinforced mine with a long angle across the bottom. Keep us posted on your findings.

 

[rvbuilder2002]

Ok, glad (sort of) that this canopy gap in-flight doesn't seem unusual. My current seals are the black EPDM rubber D profile. I suppose I can try replacing with larger dimension version of the stuff. However, I'm going to explore a side-wise "V" profile that I saw once somewhere. The open end of the V would face outward such that the breeze that wants to come into the cabin would expand and seal the gap even better. All in the hope of improving my lady friend relations.

This is a good choice but the orientation should actually be the other way around.

 

[danny]

This is kind of the same only different. When I was building I had heard about pressure from the vents stressing the canopy. My concern was cracking. I put a couple of small louvered vents in the upper baggage panel of my 9 and it's a non issue. Of course, there was that one time I forgot to lock the main latches...

 

[rvbuilder2002]

This is kind of the same only different. When I was building I had heard about pressure from the vents stressing the canopy. My concern was cracking. I put a couple of small louvered vents in the upper baggage panel of my 9 and it's a non issue. Of course, there was that one time I forgot to lock the main latches...

There is actually already a lot of air exit area, If you add up the total area on all of the ends of the stiffener corrugations in the baggage bulkhead, assuming they haven’t been purposely blocked.

 

[Thermos]

Side question - do you have boots/seals on your aileron pushrods? If you don't, you might give them a try. They decreased cockpit drafts in my RV-7 more than the canopy seals I installed.

HTH

Dave

 

[danny]

There is actually already a lot of air exit area, If you add up the total area on all of the ends of the stiffener corrugations in the baggage bulkhead, assuming they haven’t been purposely blocked.

I know. Just a bit of paranoia creeping in. My canopy already has a 3" crack and I was not in the mood to buy another so......
and that's another story.
danny