Not much dicussion on flight testing?

[fodrv7]

Frank,
Got mine airborne last March then turned 60 this month.
So there is a target for you.
Pete.

[fstringham7a]

Pete

Great accomplishment and congrats.......Early fall I should be done...BUT.....60 in April so ya beat me like a Tazzmainian Devil!!!

Frank @ sgu and slc...

[Kyle Boatright]

I strongly recommend that everyone fully explore their aircraft's characteristics at the extremes of the CG and gross weight envelope.

I know of at least two people who didn't do that (one was a -4 pilot and another was a -6 pilot). Both were very surprised at the handling of their aircraft when they loaded a passenger and/or baggage. I would submit that it is awfully unfair to your passengers if you take them up in a weight and/or CG condition you have not previously demonstrated.

In my case, I created a flight test card with 8 or 10 different weight/cg combinations, with the objective being to gradually step the aircraft's weight up to my planned gross, then gradually move the CG to the aft limit at gross.

There is a huge difference in how these aircraft fly with an aft CG, particularly at pattern speeds.

[fodrv7]

Bob,
I am very reluctant to disagree with you because your posts and attitude deserve great respect.
In this case however, it is not a matter of 'testing' the aircraft stability, but experiencing flying your RV- which is already light on the controls at normal C of G- at AFT C of G and learning how to deal with it.

It's a training exercise.

Pete.

[Ironflight]

I agree with both you guys....we really are doing what amounts to "production flight testing" on the machine....but we are training ourselves how it handles out to the edges of the envelope that we plan to use. I did a lot of interesting flight testing in my 40 because I enjoy that sort of thing...but I probably could have stolen someone else's data to build "the book" on the plane. However, it was really valuable to get the experience in all the corners (especially the aerobatic corners) before I felt really comfortable.....

Paul

[Bob Axsom]

Originally Posted by fodrv7

Bob,
I am very reluctant to disagree with you because your posts and attitude deserve great respect.
In this case however, it is not a matter of 'testing' the aircraft stability, but experiencing flying your RV- which is already light on the controls at normal C of G- at AFT C of G and learning how to deal with it.

It's a training exercise.

Pete.

I agree with the training part of the exercise. I did have some major bugs to deal with which are the sort of thing you expect in this kind of test program. They were dealt with and the plane is performing very well. But the training was equally important. I did go up to Vernonia, Oregon and I did one session with Mike Seager which prepared me for the basic flying of the machine (a delighful experience by the way) but day-in-day-out operations under the wide variety of conditions one encounters remained to be learned. I don't think we are that far apart on our views and I do appreciate your kind words.

Bob Axsom

[David-aviator]

Interesting how we look at flight testing.

Most of us are not qualified test pilots and I don't pretend to be one. We are test pilots in the sense that we fly what we build, but I wouldn't know where to begin a formal test program, say for FAA certification or to check out a new design.

Once I check the stall speeds and gradually opened the speed envelope for a flutter check, I have a good idea the airplane was built fairly close to spec and trust Van's extensive test program for the rest of it. With the stall speed, I calculate an approach speed and with the flutter test, I know the thing won't come apart on a high speed dive on the red line. The rest of it is getting into performance corners depending on what one wants to do.

It is a good idea to get educated on aft and rear CG flight characteristics but the airplane will not fall out of the sky if you don't. Just don't over control it. Like all the books say, pitch stability is best at forward CG and less so at the aft limit, but not so that the airplane is dangerous or uncontrollable. It just aviates a little differently. Same at max GW vrs flying with 12 gallons of fuel. If you are really concerned about this aspect of the airplane, the best thing you can do is let someone else check your numbers so you do not inadvertantly get outside the CG envelope. It is interesting that there are licensed pilots flying around who do not know how to compute the CG of their airplane. I have helped more than one.

The really, really critical thing about initial flight is the engine. I typically do about 4 hours of extensive taxi work, including a number of high speed runs down the runway, mostly to see if the engine will keep running and how hot it will get. I did have the Subaru quit during this process because of an anomaly with circuit protection and the fuel pumps. That was a great thing to happen on the ground.

Other than that, after a couple or three other people have looked at your work to make sure the ailerons are not hooked up backward, its push the power up and let her rip. These airplanes do fly great!

dd

[NeilMcLeod]

Well, good to see some discussion started here! This is great. I'll have more questions when I get time to get my thoughts together. I do believe that some of what we are talking about is more correctly described as flight training or familiarity checks. It is probably a little different for most of us in that we won't have a qualified instructor to show us the edges of the envelope. True these are proven designs but also true that we are not all proven builders and it is possible that our planes are not all rigged the same. The surprise that Vans had with the spin characteristics of the 7 shows that what appear to be small changes can have larger than expected affect on flight characteristics. I don't mind learning this stuff on my own but I did want to do it solo first. BTW I do fly with and have experience with a chute but I do wish I knew if it were possible to get out if nessessary, (7 Slider).

My compaint with the rudder is not the effectiveness but just the high forces. It's no probem for "normal" flight but I find that in a left crosswind that when you bring the tail up on take off that it takes a mighty stomp on the right rudder to stay aligned. Do-able but hard to do with finess. Also higher than I like on spin recoverys and hammerheads. Hard to hold full rudder in those maneuvers. The rudder pedal configuation makes it more difficult too.

Another thing, after thousands of hours in my 182 and gliders none of which did this I was surpised to find the 7 to be a tail wagger in turbulance. I hadn't heard anyone mention that before. Probably Bonanza pilots think it's normal.

Neil

[fodrv7]

Neil,
The amount of rudder required on take-off is proportional to the rate at which you raise the tail.
On my mates -8 if you just leave it alone the tail comes up itself and very little rudder is needed.

My RV7 - on the other hand- has quite a rear C of G and so some forward stick is required. But less is easier.
Pete.

[Kevin Horton]

I agree that flight testing an RV is more like production flight testing than it is experimental flight testing on an unproven design. But, these are not production aircraft, where each one is essentially identical to all the others. Every RV is unique, either due to builder mods, or builder errors. These differences can have an effect on performance, handling and engine and system behaviour.

In particular, builders should conduct a full series of flight tests at the extremes of their desired weight and CG envelope. Yes, Van provides recommended forward and aft CG limits. But, some aspects of the handling will degrade as the CG moves forward and aft, and each builder must determine within what envelope he finds the handling acceptable. Just because Van considers the handling of the prototype acceptable with the CG at 86.82" does not mean that the builder will find the handling of his aircraft acceptable with the CG there.

Many builders use scales of questionable accuracy when weighing their aircraft, and some do a poor job of leveling their aircraft. The empty weight and CG that the builder calculates may be affected by these issues. Thus when the pilot calculates that the loaded CG is at 86.82", it may very well actually be some other value, due to an inaccurate empty weight and CG. Rather than simply accepting Van's recommended CG envelope without doing any confirmatory testing, builders should carefully test the edges of the CG envelope they need for their aircraft.