Saturday, August 28, 2010

The power of an engine

A lot of people say once you move your airplane building project to the hangar, the progress you make on it tends to slow down since it's not living arm's-length away from you. There's some truth to that, although when you're working at the airport, every plane that you hear taking off on a distant runway provides a fair amount of motivation to keep plugging away.

It's even more motivating to have the guys who've been building the RV-7 one hangar down, to push it out and see if the engine starts. That was the case last night. I was on fire-extinguisher and videographer duty.

After a celebratory beer, I went back to work on the stupid cowl, adding some fiberglass so that I can sand down pieces of it to make the damned thing fit.

From what I can tell, it'll take about four or five more first-engine starts to get me to finish this aspect of the project.

Thursday, August 26, 2010

The Cowling Chronicles -- Episode One

If you've been following me lately -- and even if you haven't -- you may know that the airplane project has hit a big snag because I've worked my way up to the dastardly fiberglass cowling. The instructions I've been using have been awful. They basically say, "figure it out for yourself."

This evening, I thought, "I wonder if there was an update in the instructions since I started this project in 2001?" And, indeed, there was and it appears to answer some of the questions about why some people have been offhandedly citing instructions that weren't in my instructions.

They're still not great, but they're more informative than the dinner napkin I've been trying to read off of.

So maybe this will be the only episode of The Cowling Chronicles. I'm betting not. Enjoy.

It's the cows... still

One of the great marketing elements of Oshkosh is Aeroshell's "cows" posters featuring Amoolia. More than once I've thought, "maybe this is the year I'll skip Oshkosh," only to catch myself and say, "but what about the cow poster?"  I think every homebuilder's garage or hangar has at least one cow poster. So I've updated last year's slideshow to present a decade of Amoolia. It might be easier to view these in the full-screen view.

Saturday, August 21, 2010

Cowardice and cowling

It always seemed to me that when RV airplane builders started working on their cowling, they were near the end of their project. This week, a little more than nine years after I started building my RV-7A, I started working on the cowling in earnest.

Don't get me wrong, I've still got plenty to do on the airplane -- there's the little matter of plumbing the engine, for example -- but other than the wing tips, this will be the last of the "outside" parts of N614EF that people will see when they walk around my airplane. And therein lies the problem, of course.

I don't want to screw it up, and yet, this is the part of Van's airplanes that everyone says has directions that are not very good. Indeed, I've spent two weeks starting at the plans, and reading the instructions and it was only today that I noticed that the instructions basically say, "make it fit." Swell.

Last week, my building pal, Warren Starkebaum, flew over to South St. Paul to give me the once-over on how this is done, so I started on the top of the cowling and after three or four days of being fairly finnicky, I got it to fit as good as I think it will.

So today, I started on the bottom of the cowling, after reading several Web sites with some tips. The problem with almost all of them is they are taildragger models, whereas mine is a nose-gear model. That means you have to cut a slot for the nosegear leg to fit through.

The problem is there's really no knowledge that I've come across that tells me -- exactly -- what I need to do next... and after that... and after that. It seems to me there's money to be made here somewhere for someone in a particular region of the country to be a "cowling coach," working with a builder for an afternoon until they get past the point of no return. These things are expensive, and there's no desire to have a cowling coffee table.

Anway, I found a new use for the wing stand (which I don't need anymore because the wings are attached to the plane now).

The instructions say the bottom cowling should match the radius of each bottom corner of the firewall -- and mine does. And now I need to trim the back end to make the front end match, I guess. But this is kind of crazy.

Still, I can see how it will end up looking like an airplane.

All this fitting seems to be a two-person job. So I think I'm going to wait to do anything more until I can find someone in Minnesota who's done this before, who's willing to spend a few hours helping me get it to a final fit. After that, the sanding and then the filling and sanding of the finish, can be done solo.

Any volunteers?

Update 8/22/10

I've been sanding and grinding away at getting the two halves to fit. So far, this seems to be the best I can do. I don't want to sand too much off and make the two parts that overlap brittle. But, geez, ugly or what?

Here's the front left

Front right:

From what I've found on other people's sites, the plans call for you to drill the two halves together in the front. But I'll be darned if I can find that mentioned anywhere in the plans or on the drawing. Time to get a break, methinks.

Tuesday, August 17, 2010

High-speed taxi tests

A line in a news story about the death of RV-6 builder Alan Clark caught my attention today.

Nampa Fire says Clark was high-speed taxiing and testing his plane when wind lifted it and sent him hopping up and down before it flipped over.
I wrote an article -- or rather pieced together submissions from pilots -- on the practice of high-speed taxi tests for RV Builder's Hotline a couple of years ago.

Van doesn't like them:
We expect that the motivation for such testing is often
the eagerness to “see how it works” while waiting
weeks for that final inspection. We assume that there
are many successful, thus unreported, high speed taxi
tests and “down-the-runway” lift off flights made in new
RVs. But still we wonder…what do pilots hope to learn
from fast taxi tests and brief lift-offs that they cannot
learn from sedate taxi speeds and actual take-offs?

Well, there’s theories and there’s facts:

THEORY: It is desirable – even safer -- to perform
high speed taxi tests during the pre-test flight phase of
homebuilt aircraft development because nothing can go
wrong at speeds less than stall/take off speed.

FACT: There is little to be learned from high speed
taxi tests, other than that RVs accelerate faster than
expected, and may take flight at lower speeds than expected.

An RV is capable of flying, particularly in
ground effect, at very low throttle settings. Even at far
less than full throttle, an RV can quickly accelerate to,
maybe, 40 mph. The pilot then pulls the throttle back a
bit to hold that speed while he exercises the ailerons
and elevator a bit, to "feel it out". But that retarded
throttle position, maybe only 1/3 open, is still too much
and has, within seconds, accelerated the plane to 60+
mph – enough that in the hands of an inexperienced (in
RVs) pilot, unanticipated flight is probable.

Thursday, August 12, 2010

The next step

With the RV-7A nearing completion -- sort of (I still don't have a solution to the fuel line problem) -- I've found myself wandering, and dreaming about what I might build next for an aircraft. Then I saw this video that's been posted about powered parachutes, specifically an air tour around the gorgeous landscape of southeast Minnesota.

I'm not wondering anymore. A powered parachute it will be.

(h/t: Statewide blog)

Tuesday, August 10, 2010

Things that go bump in the night

If it weren't 1,000 degrees in the Twin Cities with ridiculously high humidity doing so, it'd be the engine on the RV-7A project that keeps me up at night.

As regular readers know, I've been working my way from the tail of the airplane to the front for final assembly. With the avionics now -- mostly -- done, the only things left (other than fairings) to get the airplane flying is (a) the engine (b) the cowling and (c) the propeller. All are pretty important, from what I've been able to understand.

Over the course of the coming winter (which can't get here soon enough), I'll be working on the various lines for the engine.

I'll start with the the fuel line from the engine-driven fuel pump to the fuel servo. And, because this is me, I've already run into a problem. See if you can spot it.

Give up? Look closer.

Pay no attention to the black hose, that's simply a support hangar for the Vetterman exhaust. It's the brown hose. As it comes out of a T-fitting at the fuel pump and winds its way forward, it's striking the engine mount. Angling the T-fitting doesn't change anything, because the engine mount is parallel to the longitudinal axis of the plane and it'd keep hitting.'

I suppose I could clamp it -- somehow -- but the engine is going to be vibrating and don't I want the hose to be free enough to "give" from the constant vibration.

Also, I'm looking for anyone who has a good Web site documenting the installation of the Grand Rapids Technology EIS 4000 in an IO-360 engine. The instructions aren't bad, but they're not as good as they could be, and I learn by seeing rather than by reading and guessing.

Update - It occurred to me that perhaps I could swap the two ports out of the fitting that goes into the fuel pump. Alas, no dice. They're separate fittings.

Sunday, August 8, 2010

False floors for an RV-7A airplane

Last year, when I was interviewing RV building expert Tom Berge on the RV Builder's Hotline (download here), he mentioned the value of false floors in the forward fuselage. Ideally, I would have accomplished at the beginning of the fuselage building process, rather than at the end of the RV-7A project, but I'm pleased to finally have gotten around to it. Tom said, and others confirmed, that putting the false floor in dampens vibration, and heat, and changes the "sound" during an RV airplane flight.

There is a price to be paid; it adds about 7 pounds of weight. But it's a much cheaper addition for flight comfort than items that cost a lot more. (Read more)

Friday, August 6, 2010

Oshkosh 2010: He did it again

I'll be damned. He did it again. The guy who put together the best video in the history of Oshkosh in 2009, has put one together in 2010.

As good as it is, though, it still doesn't capture what Oshkosh is. It's so much more than what's flying by at a given time. But he's sure come closest over the years.
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