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Gas Strut for RV-4 Canopy

Hi All,

I'm refurbishing an RV-4 s/n 3662 and would like to replace the gas strut that supports the canopy. I've been told to just pick one up on Amazon but I'm having trouble figuring out which part will fit. And I'd prefer an aviation gas strut if such a thing exists.

Attached is a pic of what I've got. In the extended position pictured, it's 10 inches from bottom to top. The body is 4.5 inches. The strut measures 3+3/8" from the top of the black body to the bottom of the attach fitting (just the silver portion).

I'd appreciate a pointer to one that'll use the same orientation of the attach hardware. Any gouge you're willing to share on how to get the right strut will also be greatly appreciated.

Thanks,
Harry
 

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What I did.."no lift" strut/snubber

I used a non-lifting snubber I liberated mine from some leftover airliner overhead bin snubber replacements. I am not an advocate of the pressurized uplifting struts, because Its a pre-load on the canopy frame crossmember that may not have been designed for that. The neutral snubber will slow the fall if dropped or wind blown, but mostly its a much more elegant solution than the original per plans string, which has caused fouling problems. I know some RV-4s have pressurized ones installed that do fine, but I also know there is quite a bit off pressure on the frame when compressed.
 

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Bill I like this idea. My gas strut has been worn out since I got the airplane, so basically functions like yours, however it is a bit too free, so I still need to be careful. I just googled around trying to find something as you describe, but am awash in a sea of gas springs no matter what I search. Could you get a brand and part number from your snubber when convenient?



I used a non-lifting snubber I liberated mine from some leftover airliner overhead bin snubber replacements. I am not an advocate of the pressurized uplifting struts, because Its a pre-load on the canopy frame crossmember that may not have been designed for that. The neutral snubber will slow the fall if dropped or wind blown, but mostly its a much more elegant solution than the original per plans string, which has caused fouling problems. I know some RV-4s have pressurized ones installed that do fine, but I also know there is quite a bit off pressure on the frame when compressed.
 
RV-4 Canopy strut

I'm refurbishing an RV-4 s/n 3662 and would like to replace the gas strut that supports the canopy.

I have a similar setup with it attached to a (reinforced) canopy frame. I was never impressed with the rope, overcentering rod, etc. It has worked well for years and has a two-way internal valve that provides resistance in both directions but no compression or extending power: rather like a shock absorber. I rescued mine from a Boeing 737 (I believe) overhead bin door, obtained from a friend who was a mechanic for United. You might ask around for someone who knows someone who has a friend!:p I believe most of the ones available on Amazon etc will have a resting position in extension, which is not ideal. Mine has no part number but that sticker was removed years ago when I painted it. I have a spare somewhere but it is in my +22 degree hangar and I will look for it once it warms up. If I can find it....it's been years..... I might be able to find a part number; no promises....

Yours looks like a similar type............ Why do you want to replace it? Is it leaking? If it doesn't have any extension power, I would look at that as being a good thing. Should just keep the canopy from slamming open or closed, which mine does, and a secure place for it to rest when it is open. Mine may work better in slowing the extension. I guess I never paid that much attention because I'm pretty busy when I am closing the canopy: CANOPY: down and locked; SEAT BELTS: locked; BOOST PUMP: on; FLAPS: set 20 degrees.........:cool: When I'm in the hangar, I'll check that out as well.:)
 
Hi All,
I'd appreciate a pointer to one that'll use the same orientation of the attach hardware. Any gouge you're willing to share on how to get the right strut will also be greatly appreciated.

Thanks,
Harry

I have done this for several airplanes. Go to the NAPA online store. select the shock type, end types, force desired and lengths (compress/uncompressed). That will return the part number you need or items very close to what you need.
 
Strut

Measure the overall length and compressed length and order one from McMaster Carr. As for force mine is 20 lbs and works fine. I’d like to try and 25 lb one.

You will however need to change the mounting hardware.

I’m making a video right now on gas struts.
 
Strut video

Will watch for the video, need to replace my parachute cord i’m using (but the cord does at least match my red tail)
 
Gas Strut

If my memory serves me correctly, it's recommended to install cylinder on top & rod on bottom to prolong life of strut. That's all I got...:p
 
Directional gas strut.....

It has worked well for years and has a two-way internal valve that provides resistance in both directions but no compression or extending power: rather like a shock absorber. Mine has no part number but that sticker was removed years ago when I painted it. I have a spare somewhere but it is in my +22 degree hangar and I will look for it once it warms up. If I can find it....it's been years..... I might be able to find a part number; no promises.... Mine may work better in slowing the extension.

Well, after a brief look through the (30 degree) hangar I did not find the spare. Opened the canopy and it is better at opening resistance than closing. Which is OK as I usually have both hands on the canopy when I am closing it. I'm not sure I would like any resistance when I am closing the canopy.....:) When I was building, I figured out geometry for it being "overcenter" enough it has been open in a relatively strong wind without blowing shut. Could the dynamics inside the cylinder have deteriorated over the years it no longer works to dampen closing? Maybe. I'll have to check that out when I find the spare. Oh: no part or serial number to be found.....

I like my setup. And it looks like it belongs on an airplane. NOT that I have any objections to a piece of rope......:p:rolleyes:
 
When I was building, I figured out geometry for it being "overcenter" enough it has been open in a relatively strong wind without blowing shut.

The gas struts are nice, but I'd worry about this - could do a lot of bad damage if it slammed down. Some kind of mechanical up-lock would help.
 
Canopy slamming shut

The gas struts are nice, but I'd worry about this - could do a lot of bad damage if it slammed down. Some kind of mechanical up-lock would help.

In the 1210 hours I have on SuzieQ I have never had the canopy slam shut. It takes quite a bit of swing to get it to come 'over-center' to allow it to close. I do not leave the canopy open when I am not with the aircraft except in the 'taxi' position. Again, even in a strong wind if I am in the airplane, I have not had problems. YMMV but I like my setup. And I don't have to reach back to undo a mechanical uplock.

I have memories of landing JUST before a storm hit and the wind was BLOWING! I had to get out of the cockpit and into the baggage compartment to get the tiedown rings and rope. I had no problems keeping the canopy open. I had closed the canopy and was under the wing tying the last wing down when the RAIN hit! It was a wet dash to the FBO! Then the lightening came.....:eek::eek::eek:
 

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