Can someone give me the skinny on a test flight. What type of things do I look for in the aircraft behavior. What should it do when I do things. I can fly as I am not new to the subject, but I am designing my first aircraft from a full size aircraft and need to know what to look out for.

Here's what I do, after all the appropriate ground checks for control movement, (in the proper direction!) battery charged, CG correct, engine broken in, fuel system working right, etc..

Ground handling is important, so I do some taxi tests, and adjust steering and throttle, if needed. Bad ground handling can end your first test flight (or landing) before you even get started. Then...

I use a long takeoff roll, and gentle elevator pressure for takeoff. (no flaps or retract use)

Next, gentle climb to higher than normal altitude, where I do a bunch of standard "full-scale" maneuvers, such as gentle turns, and aileron rolls. Next, I slow it down and check stall behavior without flaps. When I'm comfortable with the slow speed handling, I land and take a few deep breaths. Then I check everything on the plane to make sure nothing is vibrating loose, and that there are no other visible problems.

Next flight is a little more agressive. I take off and climb high again, (without flaps) and when at altitude I cycle the retracts if the plane has them and repeat the "gentle" maneuvers above. I also cycle the flaps, and observe the handling difference. Finally, I retract the flaps and gear, and start to really "wring it out" to check for structural problems... Loops, rolls, stall turns, and full-elevator pull-ups, checking for snap behavior.

Deploy flaps and gear, land, and congratulate myself. (or curse myself, depending on what happens on this last flight.)

After a few more agressive flights, with no problems, I think it's safe to assume that the plane works. If you have the money, and safety isn't an issue, I suppose the only real way to know everything about the design is to test it to destruction. I find that the universe has a way of doing that for you, at some random time in the future.

One very important thing, other than the checks on the plane. KEEP CALM!!! If you feel uncomfortable or anxious, wait till you calm down.

Just yesterday I almost lost a plane on the maiden flight coz I was too anxious. Luckily there was an experienced pilot around who grabbed my Tx and saved the plane.

I think the most important thing is to have the CG in the right place. It affects the way the plane reacts to all the other settings, geometry, etc.

Pretty much everyone already knows and is scared of having the CG too far back.

However, many make the mistake of having too much of a "good" thing and move the CG way forward. That makes takeoff much more difficult, especially when you don't necessarily know how much elevator travel is enough. You can end up pulling elevator on the takeoff roll, and having the plane leap into the air once the elevator power overcomes the nose weight. I've even seen planes do that, and people assume it is tailheavy because of the "pitch-up".

Then it will be hard to land as well, as there will be even less elevator power available due to lack of propwash. I have had a friend lose a plane on the first flight because the plane was too nose haevy and he could not get the nose up to make it over the trees at the approach end. Not big trees, just the ones at the end of the runway.

The CG ought to be 10% of the MAC in front of the neutral point of the plane for the first flight. I calculate the neutral point then use the above "rule of thumb". This has always worked very well for me. I then move the CG back to 5% or less depending on the type of plane. Of course, calculating the neutral point is the fun part. I can help you with that if you want.

I have a Futaba 9C transmitter, which is great for first flights because it has the slider controls on the sides of the Tx. These are little rotary knobs that are positioned to be under your index fingers. My little trick is to program one of them with about a 10% mix to elevator. In effect, that turns it into a second trim switch for elevator. With the mix, you can determine how much trim is available on the slider. I usually set it to have about 2x the amount of travel that the regular trim does. This gives me some advantages:

First, it's under my finger and I don't have to hunt around for it while I'm struggling with a snake-dancing airplane. No need to take any fingers off of any sticks while flying.

Second, it's more powerfull - or as powerfull as you want it anyway. I find that new airplanes need just one click more trim than the regular switch can give me

Third, the trim change is effective immediately. WHen the plane is trying to hover itself on takeoff, just slap that switch over and whamo, you got trim. Trying to punch the trim switch 18 times is again, too much for a test flight...

Once everything is set up, I deactivate this mix, as there is the risk that inadvertent deployment during sport flying would send the plane into the ground.

I was under the impression that 25% MAC was the neutral point. I will focus on those calculations again later as I did them earlier.

The spot at 25% MAC is the aerodynamic center of the WING. The neutral point of the airplane is the spot at which the CG location would result in a neutraly stable airplane - not self recovering, but not completely out of control. You don't want the CG at that location for the first filght.

The neutral point changes depending on geometry, most strongly the size and goemetry of the tail. I have a plane that has the neutral point at 70% MAC.

Oh, ok thanks I will check this out with that excel spreadsheet in time.

I always use dual rates on first flights. Why? Because if you decide the aileron roll rate is just too quick (or too slow), you have a 50% chance of changing the throw to something better. Why pass on it?

johng, tell us how you calculate the neutral point.

For CG position, stable vs unstable with a very subsonic aircraft, you should be able to use CG positions used on the real aircraft. Just don't use the extreme positions, and you might want to bias the CG forward, if anything. Good Luck! Test flying a model is one of the best parts - it gets your knees knocking!

FIRST!
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Put the c.g. per plan.
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2nd!
Check ALL controls for proper directions with the transmitter sticks. From the REAR of the plane.
Left aileron control moves the left aileron UP.
Left rudder control moves the rudder LEFT.
Up elevator moves the elevator UP.
Fast throttle OPENS the venturi.
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3rd!
Set the low-rate AND high rates.
Expect to use the low rates for the first takeoff.
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4th Run the motor AT HOME! Set idle and high speed AT HOME!
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At the field
Check 1,2, and 3 all over again!
4 will make itself known if you've screwed it up.
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First, I go over the plane's mechanics, checking everything, every linkage, hinge, bolt, etc. If it's my plane, I check it at the shop, and check it again at the field in case I missed something. If it's someone else's I check things carefully. Check lateral balance as well as the for-aft CG location.

Double check the engine mixture settings. Nothing like a deadstick on an unproven design to make your day.

As mentioned, taxi and fast taxi/aborted take off runs are a good idea.

My first takeoff is a lot like what was mentioned above, make sure you have flying speed, and keep your departure shallow and straight. Make the first turn carefully, I'm usually doing a climbing, shallow bank 180 turn here.

As soon as I complete the first 180 degree turn, I back off the power a bit to slow things down and start to trim and get a feel for the plane. At this point I should have enough altitude for a straight in shot at the field should I go deadstick, and I can relax enough on the sticks to work the trim levers easily.

Never, ever fly in to a location where a deadstick approach would be trouble. That means keeping it high, in the center, and at a comfortable distance, not to far out, not right on top of yourself.

Fly a few laps around the field, get a few breaths, and get comfortable. If I'm still fighting with the plane at this point, I'll fight to a draw, and head in for a landing. If things are going well, try a few turns with out the rudder, try a few rudder only, see how it turns best using coordinated controls, ie how much rudder does it like in turns.

If, at any point, I get a sudden trim change, or a sudden uncommanded movement, I cut power to idle and head for a landing. Something caused it, and I want to find out what. Any sign of flutter, any kind of "what was that" or "did you see that fall off" type of thing, immediatly cut power and come in as if you are deadstick. Don't think about it, land first, then think about it. I've seen guys loose planes while they were talking out "hey, what was that" type of things. Old saying from somewhere "the first emergency doesn't kill you, it's the second emergency that kills you". So at the first sign of the first problem, head in before the secone one has time to come get you.

Speaking of landing, take a second before taking off to look around. Look where cars are parked and are not parked. Look where guys are pitted or not and look for areas that would be safe to ditch in should you have to ditch the plane. If things are going really really badly, sometimes it's best to cut power and aim for the tall grass. I've lost aileron control on planes before due to aileron flutter. Knowing where things around me are made it easy to pick a spot to crash in. Since I had elevator control, I could pretty much aim the crash.

First maneuver is usually a roll to see how fast the ailerons are. Then a loop to see how the elevator handles. On some planes, instead of a loop, I just pull up as if I was going to loop, then push out after getting vertical or near vertical. Then try pushing nose down a little and pulling out. No high-speed power dive here, just feeling out the elevator.

A little slow speed flight is next, doing it way high up. I don't usually fly in to a stall here, just seeing if I can get a comfortable approach speed that looks about right. And getting a feel for how it will handle when I go to land. I test flew a guys Stuka the other day that was nose heavy. The low speed flight told me I wouldn't be able to keep the nose up on approach, so I had to use a non-normal approach to landing so I didn't run out of elevator on the way down.

Depending on the plane and it's intended use, I might do straight ahead stalls and spins followed by snap rolls next to see what happens. Usually on a later flight. I might do a straight ahead stall on the first flight depending on what I saw in the slow speed flight earlier.

I then check for signs of control flutter. This is done by starting with full throttle level flight. Then going to a shallow dive, then trying a steeper dive etc, all the while listening for any buzzing or fluttering noise or seeing any hunting or movement with the plane. If your plane is solid, but starts what looks like a little odd roll hunting, that's sometimes aileron flutter for example. Some planes will also show a bit of pitch hunting at high speeds that's not due to flutter but can be fixed.

Somewhere in here I also like to try a vertical climb as well. Just to see how much pull it has, and also check to see if the engine and fuel system is doing it's thing. Be ready for a deadstick here though.

Much of the test flying I do is with my combat planes. For those I have a bunch of specific tests that I do next to test out their handling at very high G forces, looking for snapping out of loops and turns at high speed and such.

For an acrobatic plane, there is a bunch of trimming and testing type stuff that comes next that will help you sort out the rest of the plane.

It's not something I can explain in detail over the web. I use the methods of summing the stability derivatives for the different parts of the airplane. This is the method presented in the book "Airplane Performance Stability and Control" by Perkins and Hage. I'm not trying to sound like a know-it-all here, it just took me a semester college class to put this all together in my head. Trying to explain it to someone else on a noteboard would be painfull all round.

I have the method extracted to a spreadsheet. However, the input variables are listed in coefficient shorthand and would be meaningless unless you know how to do this already. Plus, there are some terms that depend on empirical tables for input values, so you need to have the book as well. So, it wouldn't do too many people any good for me to send them the spreadsheet. However, I could run some numbers for Thunder-man when the time comes. I'm not sure which spreadsheet he refers to in post #8 though.....

For most conventional configuration airplanes - like this one - the horizontal tail is by far the greatest contributor to stability, so some folks have "rules of thumb" that compare the CG loaction the the tail volume cooeficient. THe tail volume is a measure of horizontal stabilizer power. The bigger, higher aspect ratio tail, farther from the wing, will have more stabilizing power, allowing a more aft CG. If anyone wants to present that method, by all means -do so.

Some things I can recommend without getting detailed:

1) Try out a new plane when there are very few people at the flying site. There will be lower risk of injury to people or damage to property (cars) and less concern about impressing other people. You need to be able to totally concentrate on what you are doing.

2) Try to perform the first few flights in almost calm air or light wind since the object is to visually notice anything odd about the flight and ground handling behavior of the plane. Heavy wind conditions do not help flying power planes and the risk of a crash increases.

3) If you want an assistant make sure it is someone that will be helpful and not a distraction. What you don't need is someone that panics, someone that cannot follow your specific instructions or someone that keeps yelling in your ear "Roll it!". The most helpful people I have had help me remained motionless and quiet unless something odd was noticed or until I asked for an adjustment to be made to the trims controls.

4) Never believe that everything is perfect. Expect something to need adjusted.

5) When you are done with flying on the first day go over everything on the plane to make sure nothing has changed. Check all bolts for tightness, all hinges for integrity, all radio equipment for any signs of misadjustment. The vibrations in the air can not easily be reproduced in the shop so the plane has been placed in a new environment when it was flown.

I try to test fly a plane as if I were helping someone else that brought out a new plane. I try to question everything and double check everything including the deflection of the flying surfaces when compared to stick movement even though I had done so in the shop (this is my last chance to perform a check). That means I am very careful during takoff, flight, landing and try one thing at a time until I feel that the basics are being handled very well. If done right the first few flights are extremely boring and predictable because everything was set up properly in the shop.