Flight testing...

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rsrguy3

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Hey there gents, and ladies. What are your experiences in flight testing, both while airborne and authoring poh and flight manuals?

It looks like a deal my brother and I have been working on for two a/c could cose on Monday. Neither has a poh or fm. Both are in airworthy condition and safe for flight pending condition inspections.
One aircraft has 250 hours and one 4. Don't ask me how a new (almost 18 years old) aircraft has not had the time flown off or any testing recorded... Anyway that falls to me now, I'm looking forward to the challenge.

Anyway please share some of your experiences and any tools, forms or templates you used and what kind of time it took.

Thanks in advance,
Guy
 

proppastie

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What are your experiences in flight testing
Crashed my MM1 on the first flight.....it did not fly like any factory built as regards control sensitivity, feed back, or glide......As I have said before I have had much better luck with factory built where I was able to get a check out with an instructor......

Perhaps I should have gotten dual in a Pitts, or Luscome ..... the Citabria I was flying was more like a C150 than a hot homebuilt.......good luck.
 

TFF

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Depends on where you live too for flight manuals. Homebuilts in the US don’t require one. Other countries do.

EAA has good practices for testing and what you are trying to accomplish. Remember too, the one with 4 hours has operating instructions that have to be amended to test in a different location if they are different from where it was built.
 

Twodeaddogs

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what type of aircraft? what engine?what prop? you can find any amount of test protocols on the Net. I'm guessing the 250 hr one will be a proven beast and will not, hopefully, throw up any surprises. Taxy it first and do get time on type,if you can, with an instructor. If not, then conduct your first flight close to the airport.
 

Aesquire

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Other than getting some time, or at least a briefing in type, I suggest taxi, fast taxi, ( see if it will stop ) then unbutton the cowl and look for leaks, loose bits, and anything that moved from the time you looked at it right before the fast taxi.

Then crow hop the thing. Lift off, throttle back, land. Rinse & repeat a few times to get a feel. If it pulls in any direction, you want to know before a full throttle lift off. Left/right, nose up/down? Parts fall off? I think crow hopping is highly under rated. You do need a long enough runway. ( that's why you test the brakes in fast taxi first )

For test protocols, the EAA list is pretty good. If they are certified aircraft, you should be able to get a copy of the POH from the manufacturer, if one off Ultralights from a long gone company, you just pencil in 65mph max speed, then find out what stall is at least half a mile up.

I know that all seems cynical and sarcastic, but without more information, I revert to the old school "learning to fly a strange plane" techniques that worked back in WW1. Keep in mind that killed a LOT of students, usually with stall spin crashes. If you are an experienced pilot, you should be able to skip that ending by remembering the First Commandment of fixed wing flight. "Maintain thine airspeed lest the Earth rise up and Smite thee" The Second, iirc is avoid the edged of the atmosphere.
 

rsrguy3

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When the sale is finalized I'll post pics and info... Fast taxi and crow hops were the plan... I am within the 100 mile radius stipulated in the faa paperwork. I have a 9000' runway to work with, and lots of open usable area around It.. I'll be ordering the eaa book soon. Thanks for the heads up.
 

Twodeaddogs

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Forget crow hops or fast taxiing to test the brakes. You are just asking to ding the prop. All you need to do to prove that the undercarriage works is taxy at no more than walking pace and do figures of eight. That will induce side loads and test the steering ability of the tsilwheel assembly. Test the brakes in a straight line at little more than walking pace. Any faster risks the aircraft tipping up and it really doesn't take much effort to ding the prop. Sit on the aircraft at the take off point and look ahead at the sight picture over the cowling because that is what you see when you flare to land. Your first test flight should be no more than a very short local to prove that it flues, isn't in immediate danger and is liable to land safely. That's all. Keep it simple and reinspect before flight number 2.
 

Map

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It really depends on what kind of airplane it is and when it was last flown. First, it needs a very thorough inspection to determine that it is indeed airworthy. I would include a fuel flow test to ensure that the fuel gets to the engine in the proper amounts, hoses deteriorate...

Then do a full power ground run for 3 minutes. If that is good, you know you can get to about pattern altitude without the engine quitting. As far as handling goes, even if you are current in that type, it is a good idea to do slow and high speed taxi tests prior to flight. If something is wrong, you want to find out about it before you leave the ground. Verify the instruments are working.
I recommend my book "Homebuilt Aerodynamics and Flight Testing" (caro-engineering.com), which has a more detailed description of how to prepare for a first flight, the tests cards and description of procedures needed to measure data needed for the flight manual.
If you want to write your own flight manual and none is available from the manufacturer / builder / supplier of your plane, find one for a similar airplane online and use it as a template, fill in the data from your plane.
 

tralika

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I am another who is not a fan of "Crow Hopping". If you're going to try this I suggest you do it first in an an aircraft in which you have flown regularly and are proficient. Trying this for the first time in an unfamiliar aircraft is just asking for trouble. When I flew my homebuilt for the first time I did taxi tests to break in the brakes (following the brake manufacturers recommendations) and to check the steering on the ground. I did not do high speed taxi, never lifted the tail off the runway until I took off for the first time.

The plane with four hours total time would make me very cautious. The most likely reason for someone parking the airplane after only flying it four hours is there is something very wrong with it.

If you are an EAA member I suggest you view the Webinar
Developing a Pilot's Operating Handbook for E-AB Aircraft
This is a link to the webinar but you will have to sign in to the website to view it.

 

Saville

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I'm very interested in this flight testing business and have issues of my own.

I bought my RV-8 already built but I made changes to it. So after a new W&B I decided I would do my own flight testing and build a new POH. After flying it from Texas home to Massachusetts I knew the brakes and steering were fine ;)

The changes include:

New, heavier battery (old and new in the aft location)
New prop
New left tank
New fuel lines for the left tank and one new section for the right
New fuel selector (LEFT-BOTH-RIGHT-OFF replaced with LEFT-RIGHT-OFF)
New Reiff oil and cylinder heaters (probably not a factor)
ADS-B out module

Anyway the fuel and prop flight testing was simple - circled the airport switching tanks and
flying at different attitudes at different speed.

My issues are with the performance aspects of Flight Test.

And the main issue here is keeping speed and/or direction and/or pitch angle absolutely constant so that the numbers
are valid. Secondarily, while I'm trying to do that I'm staring at the instruments and only occasionally taking a glance outside.

Now ADS-B in does help with getting some idea if there are planes around me - but only if they have ADS-B out.

How to keep the speeds and pitch constant so as to get valid data?

That's my question.
 

TFF

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Without knowing the flight skill of the pilot, hops tend to be bad. Takeoff with immediate transition to landing is pretty hard without lots of experience. Normally it would be an emergency thing. Definitely most don’t practice it.
 

Saville

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Do timed legs over a known distance. Set up a triangular course and do legs of 20 orc40 or 60 nm and do the maths thereafter. Fly 2 minute holds. Fly timed climbs.

Not sure who you are replying to. But for me, I know about flying triangular courses, cloverleafs, 4 sided, and timed climbs.

My issue is keeping accurate constant speed an d/or pitch and/or climb rate
 

proppastie

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rv7charlie

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Another emphatic No on 'fast taxi', especially if it's a taildragger. Can you dribble a basketball? No problem, right? Now, stand on one on one foot for 45 seconds.

'Fast taxi' is a bunch of very unnatural acts at the same time that no one, off the airshow circuit, *ever* practices. I can elaborate if you want, but just Don't.
 

Daleandee

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Another emphatic No on 'fast taxi', especially if it's a taildragger. Can you dribble a basketball? No problem, right? Now, stand on one on one foot for 45 seconds.

'Fast taxi' is a bunch of very unnatural acts at the same time that no one, off the airshow circuit, *ever* practices. I can elaborate if you want, but just Don't.
When I began the flight testing portion of my build it naturally began with slow taxi testing on the runway. I had earned my tail wheel endorsement but didn't have much tail wheel time.

But I understood that at 40 mph I could push the stick forward and the tail would come up. It did, and I found the little plane to be quite touchy on the main gear ... much like doing a wheel landing. After a few of those up and down the runway my building mentor suggested that I was ready to fly it. The secret for me was don't panic ... fly the plane till it stops moving. If in doubt ... don't!

Sonex recommends (as do most Sonex pilots) that these planes be flown on and off the runway three point. For the most part that's what I use but a wheel landing every now & again keeps me honest.

FWIW ... I have done crow hops and find them to be quite useful in learning how controllable the plane will be before I go around the patch in it. But crow hops are a skill that must be learned to be done correctly. Most errors occur when the wheels leave the ground and the pilot loses concentration and the plane either climbs out of ground effect at partial throttle and stalls or the pilot pulls the power and pushes the nose over to get the plane back on the ground. Both of those maneuvers will damage the plane and could injure or kill the pilot. I don't do crow hops on short narrow runways. When in doubt put the power to it and go fly.

I'm not recommending either high speed taxi test or crow hops but just to say that if you are trained and prepared these can be successful tests. But don't talk yourself into trying something you've never done especially in a new or unproven aircraft. Flying down the runway a few feet above the surface in a familiar aircraft just over stall speed is great practice. But you wouldn't do this in an unfamiliar airplane and certainly not one that has not been tested. Be careful out there!
 
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