[GETST8FRM]

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]

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]

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]

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]

Are any of you happy??

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]

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]

Curious

..........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]

strut canister up or down

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]

AHA, he said..........

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]

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.

 

[caryr]

The canopy struts do have a lifespan.

I have replaced them once.

It is amazing how nicely a new one will perform.

They are not very expensive.

 

[Noah]

I have given this issue a lot of thought as well. I also have trouble with Van's design intent, which is clearly to allow for an overcenter linkage to provide some downforce when the canopy is closed. I would also prefer to have to pull the canopy down all the way to the closed position, rather than have to provide some LIFT force on the canopy as you're closing it to prevent it from slamming closed and breaking. One result of the present design is that when you just start opening the canopy, and the struts are not yet doing anything, your lift force, applied to only one side of the canopy, imparts a tremendous torsion to the canopy which deflects it significantly (even with the stiffener braces installed at the front of the canopy). This makes it difficult (at least in my case) for both canopy latches on the aft canopy bow to go into or come out of their square holes cleanly. I have found that I need to PUSH inwards on the canopy lift handle as I am nearing the closed position in order to make the left and right latches be at the same elevation. Same goes when I OPEN the canopy, I need to PUSH on the handle on the pilots side, otherwise, the copilots side latch gets hung up. This issue would be resolved if the struts were overcoming the weight of the canopy - that is to say, if the strut anchors were moved down and forward of the plans location.

I considered moving the strut anchor points to allow this, and even searched the archives / web for info on others who have done this (I found one, but it was somewhat more complicated and added additional mechanism linkages). Moving the anchor points would also put the struts more into the pilot / copilot space. After thinking about it for awhile, I decided that Vans probably set it up the way it is to allow for the pilot to taxi with the canopy slightly ajar. This would not be possible if the anchor points were moved to a lower & more forward position, such that you always had to pull the canopy down into the closed position (unless you also added a second (higher) striker plate for the upper, quarter-turn latch to engage in). Has anybody modified theire strut anchor locations? I'd be very interested to hear from you (as would others, I'm sure).

Ultimately, I decided to leave it as is until flying, as preserving the capability to taxi with the canopy slightly ajar is probably going to become fairly important in the RV "greenhouse".

Two other thoughts. The "0100N" in the strut part number means that each strut exerts a force of 100 Newtons, rougly 22.5 Lbs. I confirmed this on a scale. They do get old and this number drops off, then they need to be replaced.

Sam, I like your idea of the fuel tube over the strut rod when parked. Nice.

 

[Bruce]

Moved anchor points

I did move the anchor points on my 7A. Moved them to the co-pilot
hinge and the other one about 6" right of the pilot hinge. Had to make
doubler plate for the pilot side of it because it would hit the altimeter or
AI in the moving position.
I am working on this piece as we speak but it did work without too
much work.
I will post pics when I get it done or I THINK it is on my website
already somewhere. 2-15-2009

Hope it helps and for the 6'4 it will make it A LOT easier
getting in and out of the plane with the struts moved.
My nickel.
B

 

[rv7charlie]

I don't know if this idea would help or not but it was a required safety mod on some Postal letter sorting equipment I used to work on. The struts had something similar to what Sam mentioned, except made of rigid tubing, permanently installed.

The trick is to install a piece of tubing slightly shorter than the opened distance between the rod end pivot and the canister, and large enough to slide over the canister. When the canopy (equipment cover, in my experience) goes up to full-open, gravity moves the tube off-center & it rests bottom on the hinge point and top against the rod. If the canopy begins an undesired closure, the canister hits the end of the tube. When you're ready to close the canopy, you reach up & center the top of the tubing as you begin to close the canopy. Only one of these should be required for 'insurance' purposes, but I haven't actually tested it on a canopy since I'm not flying yet.

FWIW,

Charlie

 

[Rupester]

Noah ... thinking about the alignment/closure problems you describe... do you have the Delrin (or similar) guides adjacent to the L & R latch strikers ? From what I read, that helps greatly with the alignment problem on closure.

 

[Noah]

Noah ... thinking about the alignment/closure problems you describe... do you have the Delrin (or similar) guides adjacent to the L & R latch strikers ? From what I read, that helps greatly with the alignment problem on closure.

Yes I do. I made these, and installed them temporarily with double stickyback tape to evaluate them. I ended up taking them out as they made the problem worse. If you look carefully at the latches, one side is smooth and one side has a head and some weld protruding out. This is the part that gets caught on the edge of the square hole because the canopy gets torqued as it's opened / closed. It's not a clearance issue. Both latches are perfectly centered in their holes when the canopy is at rest. If someone lifts equally on the copilots side as I'm lifting on the pilots side, things go up fine and stay straight. If I push as I lift without assistance, it also goes up fine. It's not a big deal, it just needs a little bit of tweaking to make it work better and I do expect to permanently install the delrin guides - they probably are just a bit too tight fitting between the latch and the the edge of the canopy bow. My whole point is that proper repositioning of the canopy anchors would have the effect of a helper on the copilots side making sure the canopy is lifted equally on both sides, eliminating any twisting and resultant misalignment of the canopy latches. It would also minimize the localized stress on the drilled canopy holes imparted by those first couple of rivets that are putting all this asymmetric load into the canopy (for those with riveted canopies). How many people have cracked their drilled canopies (perhaps on a cold day) when opening the canopy?? The pliability of the Sika (in my case) helps distribute this asymmetric load very evenly, so I'm not worried about cracking the canopy. But if I had a drilled canopy, I would be A LOT more worried about this.