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flyboy52a

Member
I am about to begin construction on an RV-4 (well, pick up the kit at least). They say hind-sight is 20-20, so I am asking all you RV-4 builders out there if there is something you would have rather done differently in the construction of your aircraft. There is nothing worse then wasting build time or re-doing work. Right now my plan is to make the basic aircraft with mods for rear seat rudder pedals and fire wall changes to accomidate an o-360(I have not decided on an engine yet). I have dreams of cleaning up the airframe to get the extra performance out of it, but I would rather be in the air sooner and revisit mods during the winter no-fly seasons. Any assistance and *good* advice will be greatly appreciated.
 
Welcome to VAF!!!!

Ed, welcome to VAF:D

I havent built a 4, so cant help you with the questions, but I am pretty sure you will get some answers soon.

Well, maybe one suggestion------use the 4 parts to build a Rocket:D:eek::D
 
RV-4

I built a -4 before the quick build kits and the RV-8 came out. I really like my -4 except for the following.

cockpit too small for long flights... I am 6-2 200lbs and after about 2 hours I have to get out of it. Would have moved the front seat back about 2-3 inches.

there have been times when I really wished I had 8 more gallons of fuel

The back seat is not very comfortable either and if you have any body of size back there you won't like the way the airplane flies.

Build a light 320 powered airplane and it will fly better than a 360 airplane and it will be faster than most 360 airplanes.

Would have done the fast back canopy style
Would have used heavier skin on the elevators or maybe the -8 horizontal stab

If money is not a factor/ fuel injection and C/S prop.

If they would have had the -8 availible when I built the -4 I would have built it instead.

what I would not do..
load it up with IFR equipment/ unless you are very profiecent you will kill yourself flying hard IFR in it.

Load it up with toy gizmo's.. put in only what you need and keep your head outside.
http://www.youtube.com/watch?v=F3P5LMtBuwY

FWIW

CM Race 34
 
Excellent question, I'm sure you will get many good responses. Here are my quick thoughts:

  • When you have the option, always choose dimpling over machine countersinking
  • Make elevators and rudders with 0.020 skin
  • Alodine (and, where possible, prime) using 3rd party resources (e.g. platers) to save time
  • Rank maintainability above cosmetics and speed
  • Rivet and Pro-Seal stiffeners to elevator and rudder skins
  • Paint the airplane before the first flight to save time
  • Install a full-swivel tailwheel at the start
  • Install the cowl with Camlocs or extruded hinges rather than the rolled hinges that come with the kit
  • Build both wings in parallel rather than serially
  • Hang the engine on the mount then the mount to the fuselage
  • Generate an as-built bill of materials during the build process so 10 years down the road you will be able to look up the details on any light, connector, component, etc. incorporated during the long build process.
I'm sure there are others I missed, but others will add to your post. Good luck.

Dean Pichon
RV-4
 
I'm just getting started myself, but took careful consideration into what other Vanheads had to say by reading from such threads. There isn't really much to the airframe to consider.

1. Consider the fastback option and get another free 5 mph. Although I’ve gotten use to the standard canopy look now, I still like the fastback look better, while some still prefer the other. I understand this option will also give you more room with the passenger when you fit Todd’s canopy with it. The fastback should also offer you more rollover protection if you ever might need it. Disadvantage is visibility when looking back, but unless you plan on doing sky writing, that shouldn’t be a problem. You can get the fast back bulkhead and skins through the Harmon Rocket people.

2. I’d stay with the .016 skins on some of the tail pieces which is standard for the kit. Some say cracking may be an issue, so go with the .020, but others insist if you do the bend a certain way and take a few other precautions, the .016 skins are just fine. And I think some of the Rocket guys still use the .016 skins as well on their high performance machines with no issues.

3. Post date to the very beginning of the RV-4 section and do a search engine. You’ll find some doing a very thread on what they would do differently if they had it over to do again. You’re not going to find any major changes; not to the airframe anyway. Basically the foot recess area for the passenger seems to be the main popular option, along with electric flaps, again allowing more room for the rear passenger. One needs to also consider electric trim. Where it starts getting a bit crazy is with the firewall forward, but you won’t have to worry about that for awhile and this will keep you busy for now. :D
 
I have often thought that were I to build another RV4 I would raise the turtle deck, as has been suggested. I would stretch the fuselage in the passenger area by five inches. I would also wide the fuselage at the main spar by four inches. This is going to mean a larger firewall, cowling, gear mount etc.
Although this sounds like a big deal, all of those parts are available and will not take any longer to build then the stock RV4.
Now you have the option to use a larger 540 engine or stick with the smaller four cylinder lycoming. If you want the smaller engine it will have to be moved forward but again, the parts are available.
Either way you will end up with a much larger more comfortable cockpit and is there any one who does not salivate at the sight of a rocket?
 
Well the fun is just about to begin. I cant disagree with Tom Martin as I am building a rocket myself but the RV4 is a fantastic airplane all by its self. I flew mine for 16 years and enjoyed every minuete of it. I wouldnt change to many things that I did on mine. I would definatly take the time to install droped floors for your passengers comfort. I would definatly install the electirc flaps they are a room saver and the weight doesent amount to much. Electric trim is also a nice option and helps clean up the interior looks of the airplane. I would make sure that I insulated under the floors and would be sure to install boots over the aileron torque tubes to prevent air from getting in under the floors. Even though I am building a rocket I still believe the 0320 and the fixed pitch prop is the best combo for the airplane but to each his own.
Good luck with your new project.
Ryan
 
RV-4 Build Decisions

The common answer that everyone gives is to go with the fastback, and I think I will. I took a quick look at the harmon rocket sight and it appears that the fast back bulkheads are rivited to the existing bulkheads to provide the vertical extension. Is this a tricky mod when you factor in the change to the canopy? While the Rocket looks good, I think I would rather keep the RV-4 light and go with the 0/IO-320. When I flew a friend's RV-4 I rememer it needing some weight to move up front, maybe a CS prop would solve that issue. I have also heard the issue about the tail skins brought up a few times. Is it my understanding that some people find a sufficient fix is to simply rivet a few more stringers to the skin? Thank you all for the advice.
 
alot of good points mentioned

I have over 500 hours on mine and the elevator skins have no cracks. I did make the stiffeners longer with one more rivet at the trailing edge and I did add a dab of RTV right there so the skin couldn't flex. I like Dave Anders elevators.. with the extrusion that the RV 9 uses?

Enjoy the build, it was one of the most rewarding things I have ever done.

cm
 
flyboy52a said:
... I have also heard the issue about the tail skins brought up a few times. Is it my understanding that some people find a sufficient fix is to simply rivet a few more stringers to the skin? Thank you all for the advice.
Click to expand...

Per the HRII plans, you can stay with the 0.016 elevator and rudder skins and add an internal 0.016 doubler internal to the trailing edge. It's bent to the same angle as the trailing edge, and is just wide enough to catch the aftmost rivets on the stiffeners.
 
Dream

USE AN O-360,,BUILD IT LIGHT, KEEP IT UNDER 900 LBS (IT CAN BE DONE) build it stock and you will have my dream airplane....A poor mans P51. I know as I flew mine for the first time in 1992 but sold it later so my wife could sit along side me in my six.... bad move.
 
That brings up an excellent question. Does anyone have a break down of the component weights for the aircraft? Building an aircraft as light as possible is always a goal, I was wondering where most of the extra weight usually comes from and where I may be able to cut off a few pounds.
 
flyboy52a said:
That brings up an excellent question. Does anyone have a break down of the component weights for the aircraft? Building an aircraft as light as possible is always a goal, I was wondering where most of the extra weight usually comes from and where I may be able to cut off a few pounds.
Click to expand...

The early (and light) RV-4's were built with an O-320, wood prop, minimal paint, a handful of analog instruments.......and nothing else. Weight has increased over the years as builders decided this path wasn't elaborate enough for their tastes.

A light RV-4 is a very simple RV-4.
 
Sam Buchanan said:
The early (and light) RV-4's were built with an O-320, wood prop, minimal paint, a handful of analog instruments.
Click to expand...
I suspect these days, a Dynon weighs less than a standard 6-pack of analog gauges, provides a lot more avenues for expansion if you decide you want it, and leaves a lot of room on the panel so you could get your radio out from between your knees if you wanted to. It's probably comparable in price, too.
 
Keep it light

hi there,

I was able to keep my light (961 lbs) for an O-360 with a metal prop. I think going with a half-polish/half-paint scheme saved probably 5-10 + lbs. Yeah, it's work to keep it up but it's worth the effort.

Go with a simple glass cockpit. I have an AFS-3500, a Garmin 496, a Garmin 327 and an XCOm radio which doubles as a very capable intercom. I bet this saved 10 lbs versus the old steam gage setup.

I think if I were building again, I'd go with the HW (Safeair?) tanks. Not for the range necessarily, but so I wouldn't have to fill up as often. It's always a bummer when I have to stop more often to fill up (just for daily flights). You can also get more fuel when you stop someplace cheap.

Get a tinted Todd's canopy (even if you don't do the fastback thing). Less expensive, easier to finish and the tint is worth it.

Maintainability is huge . . . make sure you can get to your battery without too much of a problem, and same with your oil filter. I'd skip the gascalator (that was per Van's recommendation, by the way).

Rick
 
Snowflake said:
I suspect these days, a Dynon weighs less than a standard 6-pack of analog gauges, provides a lot more avenues for expansion if you decide you want it, and leaves a lot of room on the panel so you could get your radio out from between your knees if you wanted to. It's probably comparable in price, too.
Click to expand...

The "handful of analog instruments" I was referring to was far less than a "six pack". The early, light RV-4's were VFR planes in every sense of the term.

I agree, a Dynon D180 (and nothing else instrument wise!) would make a nice panel for a light RV-4.
 
I am certain that I will be going with the fastback. Is the Todd's canopy designed to mate to the HR-rocket fastback kit? I sent those guys an email but have not heard back from them yet.

I think I may be going with this into the panel. http://www.dynonavionics.com/docs/news_technology_preview.html
What back-up analog instruments would be required or recomended?

I have thought about going with the all aluminum look. I like the weight savings, but am worried about the corrosion. The issue is that I can leave for work and not get home for 6 months. I would hate to return only to find the hanger has been leaking on it since I left. A nice layer of paint is peace of mind. Now that I am going with paint, is there any way to fill the rivets with out adding 35 lbs of weight to the aircraft? I like the glass look, but don't like the additional weight of epoxy primer and fill to get the job done. Is it possible to stick with zinc cromate and body filler where needed? A friend who is an expert with metal work plans to help me build, so I doubt I will have a lot to fill.

One final thought on weight savings. Would there be much benifit in replacing the metal seats with a fabric seat (think j-3). As I don't have the kit or plans yet I do not know if this is even possible.
 
flyboy52a said:
I am certain that I will be going with the fastback. Is the Todd's canopy designed to mate to the HR-rocket fastback kit? I sent those guys an email but have not heard back from them yet.
Click to expand...

I'm sure they will be back on the weekdays. AX-O documents his fastback conversion quite a bit in this thread that is still active. He mentions taking a standard RV-4 canopy frame that he cuts in multiple places and re-welds it and bangs in back into shape. He also used the canopy from Todd’s, and says in his thread it has worked out quite nicely, as you can tell from the pics.

I think most people use a combination of micro-balloons and different kind of resin for filler if they really want to fill the rivets, but I don’t think most do this.

In the construction manual, it says a very minimum two coat paint job that still looks good can be done that only added 12 lbs. They didn’t use primer though, even though the paint manufacturer required it. They did other prep work, and I have no info on how it held up over time.

Spend some time on the primer section by post dating to the beginning. Wealth of info there. You’re going to find, if you go with the minimum .5 mil coverage on even some of these epoxy primers, it shouldn’t add more than 3-5 lbs to prime the entire inside. It’s a good insurance policy. These planes tend to have a higher resale value too.

Even though it’s great to watch the weight of a plane, you’re not going to notice any difference in top end or cruise speed even if you added 50-100 lbs. You would notice it on climb rate (3 feet gain for ever pound saved) and overall handling though.
 
flyboy52a said:
They say hind-sight is 20-20, so I am asking all you RV-4 builders out there if there is something you would have rather done differently in the construction of your aircraft. seasons.
Click to expand...

Here is one such thread I finally found from about two years ago which is specific to 4 builders on what they would do differently. Four pages of good material to cull over.
 
flyboy52a said:
Is the Todd's canopy designed to mate to the HR-rocket fastback kit?
Click to expand...

If you want to use the fastback bulkheads from Harmon, you will need to get a Harmon Rocket canopy. The regular -4 canopy does not follow the contour of the Harmon fastback. Todd's canopy is bigger and thicker (= more weight but a little stronger than vans)

If I were to do this again, I would not use the metal canopy frame. I would just build one out of glass (like an EZ). I would also make my own bulkheads. The ones from Harmon did not fit. I cut every one of them in half and all the flanges of the bulkhead behind the copilot seat.

There are a lot of other stuff I would do different and probably will (next plane). I have been meaning to write a lessons-learned document for people on the conversion but have not had the time. I am going on travel soon, may do it while I am stuck in the hotel room.
 
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