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Progress...Canopy Install, etc.

PlaneBuilderBill

PlaneBuilderBill

Well Known Member
Here's the latest on my "4" build. My "Todd's" canopy is clecoed on and I'm working on the sheet metal (hinge side first). I've also mounted a gas lift strut to make the canopy opening/closing a lot nicer. More as the project continues.

http://img126.imageshack.us/img126/4843/canopysidesa65068gz.jpg

http://img126.imageshack.us/img126/5135/canopysidesc65063ox.jpg

http://img126.imageshack.us/img126/2580/canopysidesd65063yx.jpg

http://img155.imageshack.us/img155/8955/canopystruta65066tz.jpg

http://img126.imageshack.us/img126/4378/canopystrutb65060ml.jpg

Bill Freckman
Grapevine, TX
 
Bill - more really useful pictures thanks. She looks superb.

If you have the spec of the gas strut, force and length , I would be very grateful because you have obviouly worked out the geometry. Also, sometime I wonder if you could give us a better picture of the bracket. I am struggling to see how you have made that and it looks nice and tidy.

I was talking to another builder the other day and he raised the issue of how the canopy would disconect from the gas strut if for some reason it came off in flight. He was worried that the strut would make the issue even more serious. Any thoughts about that? My own view was to make sure it did not come off. Since I dont wear chutes I cant see I would ever be better off without it than with it.

Thanks, steve
#4478
 
gas strut...

I also have the strut and have wondered about ejecting the canopy. If you were going down in water, you might want to get rid of it. Other than that, I can't see a scenario either. Nonetheless, it is a capability that's built in. Why lose it ?

I think I may replace the nut on the canopy end of the strut with a washer/cotter pin combo. I could then pull the pin, and dump the strut if I were going to get rid of the canopy.

I also think that if you did try to eject the canopy with the strut attached, you might have a canopy swinging around attached by the strut. Not good...

John
 
Steve,
Here are some additional pics of the strut mounting... I honestly don't think I'm going to worry about a canopy eject as there are only two small wires that act as the swivel-ball keepers...I've messed with them and they will give way easily when put in a shear situation, but under the normal swinging motion they are very satisfactory.

http://img274.imageshack.us/img274/2442/canopyliftstruta67069gx.jpg

http://img130.imageshack.us/img130/2125/canopyliftstrutb67064qh.jpg

http://img130.imageshack.us/img130/8907/canopyliftstrutc67062th.jpg

http://img130.imageshack.us/img130/6906/canopyliftstrutd67060qc.jpg

Please note all of the pics show items in a "fitting" mode....the proper fasteners,
bolts, washers and nuts will be utilized.

Thanks,

Bill
 
Gas strut bracket

Bill - thanks. Really helpful. You have made it very simple and effective. Good design. I think I agree with you about the wires giving way.

Is the strut the one VANS sells? I am still worrying about its spec.

Steve
#4478
UK
 
Steve the Gas Spring Assembly (p/n 05-01177) is from Aircraft Spruce. It has a continuous force of 45 lbs. and a stroke length of 3-1/8". I believe it's overall extended length is about 10".

Good Luck...Bill
 
Gas Strut Installation

I believe that in general gas struts should be installed with the "big" barrel end oriented upwards. Gravity will then keep lubricant around the packing where the extending rod emerges from the barrel, and the strut will have a longer life.

Examination of automobile rear hatchback installations seems to confirm that the "big end up" orientation is optimal.

Hawkeye Hughes
Skyote, RV-3's
 
Canopy installation

Bill - Thanks for the spec. of the gas strut and detailed photo's of the installation, Excellent.
One further question, what made you choose the Todd canopy over the the "standard" Van's?

Glad to see the -4 community is becoming more active. These threads are exceptionally useful to those who are still tackling problems that have been solved before but not documented. Let's keep it going................Please :)
 
Andy,
Thanks for your kind comments....Todd's Canopies are just better! Much more optically clear. I bought thicker (1/4") and Todd just about trims the canopy to the final fit! And the price is right $300 + shipping (Two or three builders can go together and the shipping is the same as one). Todd also has the standard you mess up the first canopy and the second is half price guarantee! What more can you ask for?
As far as the position of the strut goes, I'll turn mine over tomorrow and check on the results as time goes by...
Bill Freckman
 
RV-4 rudder pedals

hi Guys.

i just purchased a 4 for San Diego. It has 400 hrs and a 160 horse 320.
I just made a center panel to hold the master light, cig lighter and hobbs meter and had installed it and was pushing on the rudder pedals to get the feel of it between my legs. all of a sudden the right rudder pedal popped and went to the floor. i pulled off the upper deck in front of the canopy and found that the cotter pin that holds the clevise pin in had failed. 1 ear of the cotter pin broke off and that let the curve of the other ear circle around and come out. i can't believe how lucky I am to have this happen in the hanger. if it would come off during a takeoff I would have gone in the ditch. I replaced both pins with a 3/16" machine screw with a shank that let the rudder pedal and the clevis sit on a threadless smooth shank. I then used a nylock castle nut and cotter pinned that. it will never come off again. I enjoy your threads. Keep it up.



Bill.
 
Wow Bill,

That WAS very fortunate to find that problem on the ground !!!

I've read of a similar failure a few years ago where an RV-4 driver was in cruise flight when the clevis pin worked it's way out. Same failure mode, the cotter pin broke after the bent end of the pin had worked back-and-forth against his shoe. After it came loose, he apparently saw the clevis pin rolling around on the floor, tried to reach under the panel and fiddle with it to get it back together, but couldn't. He eventually landed safely, but I think he had to use one hand to tug on the loose rudder cable during the landing. I'm sure he had his hands full on that one.

I've heard of a couple of folks who installed tension springs on their RV-4 rudder pedals/cables, because they didn't like the way the cables sagged along the sides of the cockpit when there was no pressure against the pedals. If they had the same failure as you, then the spring would cause the rudder to deflect and make the problem even worse.

I think your fix is a GREAT idea and I plan to do the same when I assemble my cables and pedals. Can never be too careful when dealing with the integrity of the control system.

Thanks for sharing the story, and Congratulations on your new -4 !!
 
bill price said:
...all of a sudden the right rudder pedal popped and went to the floor. i pulled off the upper deck in front of the canopy and found that the cotter pin that holds the clevise pin in had failed. 1 ear of the cotter pin broke off and that let the curve of the other ear circle around and come out. [snipped]
Click to expand...

That is covered by a service bulletin from Van's.

SB 96-12-1

That bolt should nolonger be cotter pinned, it rubs against your foot and will innevitably fail. It has done so on many -4's. I squished the bolt with a flat set. It's not going anywhere without snapping in two.

-Bruce
 
RV-4 rudder pedals

Bruce.

What do you mean by squished with a flat set? I also put the head of the bolt on the foot side and the nut and cotter pin between the edge of the pedal and the side wall so there will not be anything wearing against it. Is this OK?

Bill.
 
Canopy strut and beyond...

Guys,
To answer a couple of above questions, Canopy covers are available through Van's. they sell two types, a light and heavyweight. Unless you park outside alot, the lightweight is the way to go. I bought mine from Lynn Cunningham of Cunningham custom covers (in trade-a-plane)that works great and is very lightweight and strong. I too used Nylock Nuts on my rudder pedals after hearing a couple of war stories. Another area of high wear is where the cable attaches to the tailwheel springs on the rudder bellcrank. I eliminated the standard big spring setup and went with $4 worth of Ace hardware cables, ferrules and small ss springs to get a much better arrangement with my Aviation Prodiucts INC tailwheel.

Here is a picture of my gas strut setup on the Bandit. I didn't like alot of the installations I saw out there. Many of them looked as though a strong breeze would fail the strut. With that in mind I threaded aircraft rod ends onto the gas strut and I drilled a small hole into the strut, draining the oil and reducing but not eliminating the restriction. I also mounted the strut onto the roll bar on both ends, much stronger than the aluminum plates I have seen. With geometry in mind (not that!) I used the longest moment arm I could muster with available gas struts at NAPA. The result is a very sturdy system that has been trouble free for 1000 hours. Hope this helps...RR


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Which Canopy?

Bill - You made your choice of canopy on quality, cost and the fact that you could have it tailor made to your spec. with regard to thickness. Todd do appear to make excellent canopies. What is the consensus of other builders if they had to choose again? How good are the "standard" Van's canopies? Having not ordered the finish kit yet it would be great to know the pro's and con's. Van's Vs Todd?
 
Andy,
I used Van's canopy on my 6A...it was fine except for a bit of optical waviness expecially near the front part of the canopy as it nears the frame. The plexi started life as a piece that was 3/16" thick...not exactly sure what it finally measured...but from the pics of some bird strikes I 've seen, I'd always opt for thicker if I could get it. It also had a fair amount of trimming to do. Just my 2 cents.
Bill
 
Bill - Thanks for the info. I'm still chewing on which canopy. I do like the look of the Todd and I've never seen a bad report.
 
Bill,
I tried to send this as a private message but I don't think it worked, so I will send it here. On someones observation, recommendation, mention or something, I was under the impression that the gas spring assembly sold by Aircraft Spruce would work on the RV-4 to open the canopy. I bought it without making measurements on the plane (First mistake). There is no way I can figure for it to work and open the canopy sufficiently to allow a pilot get in and out of the plane. It is a little over 9 inches in length fully extended with a 3 1/8 compression range. All my mesurements indicate that the gas spring should be approximately 12 3/4 inch in length when it is fully extended and compress to about 8 inches in length if the bracket that attaches it to the fuselage uses the rear bolt that holds the rollover bar to the fuselage. I have found someone's photo that I got off the web (may be yours) and it appears to be as I meaure it to be, about 12 or so inches in length. Any info on this?

Bob Mears
[email protected]
 
Canopy Gas Strut

Bob,

I've sent along a couple of pics from Matt Dralle's 4. I had talked to him and he used a surplus strut from Boeing. I couldn't buy one like it, but the AS strut is as close as there is. Let me know if this helps at all. I know it's a real head-scratcher....

Bill

canopybrace1tg7.jpg

canopybrace2hn8.jpg
 
Your pic reminds me of something that has me a little concerned about my own canopy strut. What happens if I gotta bail out? It seems that such a robust strut would not give way in a canopy jettison situation, and would instead simply allow the canopy to flail around smacking me in the noggin.
 
I purchased a RV-4. I am not a builder but I had a canopy departure and need some advice on the construction of the new one. How did you determine how to fit the canopy to the frame? How do you get the holes properly aligned? and how does the two skins mate/connect on the rear of the canopy. Help I have no instructions.
 
RV-4 Canopy Departure

Bill, I am not a RV-4 builder but I had a canopy departure on my RV-4 during takeoff. I am presently constructing a replacement canopy. How did you fit the canopy to the frame? How do the skins mate on the rear? How do you make sure the holes in the frame, canopy, and skins match? Trade you my canopy depature story for help. :eek:
 
I used a plexiglass drill bit to drill the holes in the plexi first. Then used the plexi as a drill guide and drilled into the aluminum tubing that the canopy sits on. Fitting the aluminum skin is just a matter of trim and fit and trim some more. Some builders just overlap the canopy skin where they meat in the back. I messed that part up so I made a small splice plate that went on top of the joint where the two skins come together in back. If you're reusing your canopy frame, you can just fit the skins to the frame and then back drill the skins through the holes in the frame. When everything is looking the way you want, rivet the skins to the frame and pop rivet the canopy (and overlapping side skins) to the tube that the bubble attaches to.

If that doesn't make any sense let me know, I'll try to clarify. :)
 
A question for PlaneBuilder Bill?

Bill, I have been messing about trying to fathom out how you installed your gas strut from the very useful pictures you posted below. Example here. I cant find enough space between the roll bar and the centre bulkhead flanges, to do what you did.

I see the flanges on the centre bulkead of your canopy frame face aft (or is it an optical illusion)....mine face forward. Did yours come like that from VANS or did you re weld it?

Thanks, I am going nuts!
 
Strut Inf

Steve,

When I was converting to the Rocket T'DecK I rewelded it facing rearward as it looked cleaner to me. Also it seemed to me that it should just be made that
way with the open side to the rear.... I've also reworked the lower mount so I'll have to post some new photos.....

Sorry you think you're going nuts, it's just a vague area with lots of possible variables...
Bill




Steve Sampson said:
Bill, I have been messing about trying to fathom out how you installed your gas strut from the very useful pictures you posted below. Example here. I cant find enough space between the roll bar and the centre bulkhead flanges, to do what you did.

I see the flanges on the centre bulkead of your canopy frame face aft (or is it an optical illusion)....mine face forward. Did yours come like that from VANS or did you re weld it?

Thanks, I am going nuts!
Click to expand...
 
Prop it up...

Bill,

Here is my tried and true setup. It is a NAPA gas strut for a dodge minivan back window with a small hole drilled in the bottom and the oil/gas removed. I didn't like the restriction of movement. The strut completely hides behind the canopy skirt when closed. I threaded aircraft rod ends on to make it even stronger. I also felt a longer strut was better for more leverage and strength. It has served me well for 10 years.

Rob Ray
1500 hours on "The Bandit"

 
Air Vents

Smoke,
Off topic, but what's the success of your NACA vents on the canopy? I'm considering Bob Avery's version with the duct on the left lower wing and scat ducting - high pressure area/good drainage - but yours looks pretty simple.
 
Hot Air...

Hi Bill,

NACA ducting on RV4's is a "hot" topic for sure...:) I have seen and tried everything on mine to include a NACA Duct on the lower fuselage by my left knee, two canopy rail Ducts and 2 Larry Vetterman "twist-out" ducts that close flush.
When I built the Bandit (89-95) the canopy ducts were "in vogue" but as I found out, highly ineffective. It is a low pressure area. My left leg NACA gets quite a bit of warm air down low as it flows (I believe) from the heat over the cowling through my vent into the cockpit. The best vents I have overall are Larry Vetterman's "twist out" vents that close flush and open out into the slip-stream.
Four of them mounted on the fuselage sides 4" below the canopy rail on either side in the front and back seat (2 front LR, 2 rear LR) would provide lots of air in any flight attitude. If I did install a NACA Duct, I would place it on the underside of the rear cowl cheek with the scat routed through a 2" hole in the fuselage. You could glass it up before you mount the rear cheeks on the fuselage. My friends "Cheez" and "Hollywood" (Safe Air One guys) both have their RV4's set up this way with excellent results.
The simplest and best though would have to be the German RV4 featured on the website below. He has a scoop that opens into the breeze. Detailed pics are on one of the links on the left, just browze all of them. It's a great site and good practice in your HS German.

Whatever blows up your skirt...:)

Rob Ray

http://www.rv-4.de/
 
Smokey-amen brothah!

As we try for the best cooling airflow thru any orifice, remember this, that the venerable NACA duct was invented as an inlet to prevent ice accreation for any induction air, not as an ultra efficient scoop.

At SnF one year, I attended a lecture by a gent named Zehrbach who was speaking about cooling drag, etc. He handed out a paper by NASA that showed various openings and their Efficiency Rating. This rating was based on velocity and volume of air upstream of the opening and comparing it down stream of the inlet.

In other words, how well does the inlet shape allow air to enter the airframe? It was expressed as a %.

Completely round inlets- 94% efficient :D
Rounded rectangular inlets (a la Vans std cowling)- 89% efficient :D
NACA duct-50% efficient :(

Naturally, where you locate anything on the airframe also has alot to do with the airflow available. For example, the RV-8 PAX NACA duct is on the underside (high pressure) of the rt wing. It blows your hair back, and it's a NACA duct which is only 50% efficient.

Low pressure areas, said Zehrbach, were places where the air was accelerating, usually a place where the surface is turning a corner away from the slipstream. These places, he said were great for creating suction to get air out of the vehicle. For example, on the underside of any RV fuselage just aft of the rear wing spar where the skin starts to angle upward toward the tailcone. Here, the air is speeding up and would be a great place to induce suction, but not generate pressure (unless of course, you put something like a scoop protruding into the slip stream (p-51 belly scoop).

Art in Asheville.
 
PlaneBuilderBill said:
Steve the Gas Spring Assembly (p/n 05-01177) is from Aircraft Spruce. It has a continuous force of 45 lbs. and a stroke length of 3-1/8". I believe it's overall extended length is about 10".

Good Luck...Bill
Click to expand...

Bill, I have that part now but I am really concerned about the 45lbs load on the hinges. Are you still happy with it now you have the canopy together? Thanks,
 
Gas Strut

Steve,

Yes, I'm still pretty happy with it. I did re-position it slightly (I'll post a picture or two when I remember to take my camera to the hangar). In fact the only thing I worry (not really worry, just heavy wonder) is that the strut has enough "muscle" particularily as the canopy is closing. I know it's not the total answer to avoid a "slam" shut, just as the struts weren't on my 6A Tip-up canopy, but I was hoping for a nice smooth transition. So far it does pretty good!

Bill
 
Bill, nice pictures thanks. I am interested that you have repositioned the strut as you have. I would have thought with the pivot closer to the canopy hinge line, its ability to control the canopy was reduced?

It seems there are very few options as to how to do it in fact, and all routes appear to have this problem of not controlling the canopy at the point of shutting. I have installed mine very similar to your first approach and it will certainly protect it from the wind when open, but will still have to be shut carefully.

When I have tidied things up | will get some pictures together.

Steve.
 
Progress...Canopy Install

Is that your ELT antenna mounted on the right side of the rear bulkhead? That is exactly the place I mounted mine. I did not want to drill holes for an antenna on the rear turtle deck so that was the best option I could come up with.

Jerry Isler
Donalsonville, GA
RV-4 N455J (45.7 hrs)
 
ELT Antenna

Yes,
I mounted the antenna on an "L" bracket right where the longeron comes through the aft seat back bulkhead. the actual unit is mounted aft just to the side of the elevator push-rod bellcrank.
I have some photos somewhere....I'll post them later.
 
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