Gas Strut ? For Tip-Up

GETST8FRM · #1 05-14-2009, 03:53 PM

Recently purchased an RV-9A with Tip-Up canopy. About halfway down, the struts loose ability to hold up weight of the canopy. I have dropped it once & the wind has blown it down as well. This is a MAJOR problem. I want a set of struts that will give resistance ALL THE WAY DOWN.(Me pulling the canopy latch from the top until it can be secured). Any idea where I can get them? Any specific PSI? Any specific make/model numbers? I have repaired a crack already & don't want to again. I appreciate your advice.

Vlad · #2 05-14-2009, 04:12 PM

Evan,
My struts markings say STARBLUS LIFT-O-MAT high pressure

There is also a row of digits below 752819 0100N 155/07 A 5.

I have read an account where the builder urged to install struts mounts in proper places. It is important to have proper leverage. I have a schematics from Vans somewhere let me know if you need it. I will try to locate.

roee · #3 05-14-2009, 04:17 PM

Evan,

I think you raised two separate issues here. I'll address them separately:

1. The geometry of how the strut is attached is why you have strong force holding the canopy open when it's fully or nearly fully open, and little to none (or even negative force) holding the canopy open when it's fully or nearly closed. I'm sure it was designed that way deliberately. But if you really want to have the struts exert a strong opening force on your canopy in every position, then what you need to modify is the geometry of the strut installation, not the type of strut. You would need to have the strut oriented more or less perpendicular to the canopy side rail in every position, whereas in the stock configuration it's more or less parallel (and even over-centered) when closed.

2. If I understand correctly that you also don't think the struts are exerting enough force on the canopy to hold it open when fully open (under some reasonable wind condition?), then that problem could be remedied by using a higher force strut. But then of course you'll be exerting stronger forces on the canopy and deck structures, and you'll have more flexing and deformation and possibly damage if the extra force is excessive, so keep it within reason. Also, if the wind was not head-on, then it would cause a twisting action that could damage the canopy, and the struts no matter how strong wouldn't help against that. Probably best to just not leave the canopy open in high wind.

-Roee

db1yg · #4 05-14-2009, 06:30 PM

Hi Evan,

I had a similar problem at about 100 hrs on my RV9a. The left strut became weak and allowed the tipper to drop if I did not manually control the closing. I contacted the manufacturer (got the tele # off the internet) and ordered a new strut with slightly more nitrogen in it. The "resistance strength" of the strut is governed by the nitrogen pressure and you can order the exact outer dimension strut with slightly more strength---it is a bolt on replacement.

Be sure the strut is installed with the attach points where the plans call and that the strut is mounted with the canister end up. If the canister end is not up you will not get the increased resistance as the canopy approaches the closed position as was intended.

I looked in my files for the part and tele # but could not find it -sorry.

Hope this helps.

Cheers,

db

GETST8FRM · #5 05-14-2009, 06:53 PM

Are all of you happy with the forces used to keep your canopy open? Do any of you have the same problem with the canopy having the ability to free fall at 50% down? How do your canopies close?

By the way, I love my new RV. Bought it from the nicest man in WI. What a change from the Cessna!!

I appreciate your input / help.

Sam Buchanan · #6 05-14-2009, 08:01 PM

Quote:

Originally Posted by GETST8FRM

Are all of you happy with the forces used to keep your canopy open? Do any of you have the same problem with the canopy having the ability to free fall at 50% down? How do your canopies close?

By the way, I love my new RV. Bought it from the nicest man in WI. What a change from the Cessna!!

I appreciate your input / help.

Evan, welcome to RV-dom!

You are describing the more-or-less normal way an RV tip-up canopy closes. You can expect the canopy to drop when it comes down to less than half open.

The tip-up is a fantastic canopy (been flying mine for nearly ten years), but it requires more care than the sturdy doors on the typical spam can. My personal practice is to never walk away from the plane with the canopy open except in a protected area like an enclosed hangar. Treat the canopy gently, don't let anyone who isn't familiar with it attempt to open it, and never leave an opened canopy exposed to propwash or the wind.

For open canopy display at airshows when I am standing near the plane, I put a length of slit rubber fuel hose on the exposed rods of the struts. These will hold the canopy open without the risk of an inadvertent slamming of the canopy. When the canopy is allowed to slam shut, there is great risk if breaking off a corner of the plexi (not to mention personal injury)......and this will make you sad.

PCHunt · #7 05-14-2009, 08:39 PM

Quote:

Originally Posted by db1yg

..........Be sure the strut is installed with the attach points where the plans call and that the strut is mounted with the canister end up. If the canister end is not up you will not get the increased resistance as the canopy approaches the closed position as was intended........

I have noticed that some builders install their struts "canister up", and others "canister down". I don't understand why that would make any difference in the forces the strut provides????

Stevea · #8 05-14-2009, 10:34 PM

It makes no difference in the force exerted by the strut. It DOES make a difference in what happens when the strut reaches the end of its stroke. Canister up results in a soft stop at the end of the stroke. Canister down results in a hard clunk.

PCHunt · #9 05-15-2009, 12:03 AM

Quote:

Originally Posted by Stevea

It makes no difference in the force exerted by the strut. It DOES make a difference in what happens when the strut reaches the end of its stroke. Canister up results in a soft stop at the end of the stroke. Canister down results in a hard clunk.

.......as the LIGHT came on!

Learn something every day, thanks forum!

Jamie · #10 05-15-2009, 05:36 AM

Quote:

Originally Posted by Sam Buchanan

For open canopy display at airshows when I am standing near the plane, I put a length of slit rubber fuel hose on the exposed rods of the struts. These will hold the canopy open without the risk of an inadvertent slamming of the canopy. When the canopy is allowed to slam shut, there is great risk if breaking off a corner of the plexi (not to mention personal injury)......and this will make you sad.

What a great idea, Sam!

I had my tip-up canopy slam closed when my hand was on the rollbar. I had not opened it all the way (but thought that I had) and when I stepped up on the right wing it slammed down on my hand.

My hand caused the canopy to twist into the rollbar and broke off a chunk of plexi. I winced as I heard the chunk of plexiglass slide across the left wing and then onto the ramp.

I glued it back into place and will probably put a fiberglass targa strip (or whatever they're called) across the rear of the canopy.

With the plexi glued into place almost no one notices the break unless I point it out.