What makes a good maiden flight?

rockyboy

Skill Collector
Mentor
When it comes to that initial "maiden" flight of an airframe, I often take the approach of "throw it in the air and see if it comes back in one piece". Probably not the most effective way to learn, especially with a scratch built or kit built.

So my intention with this thread is to start some thoughts on what are good objectives - things we want to learn - from a maiden flight, and ideas on how to test them in ways we can learn from more quickly and less painfully than a "fly, crash, apply hot glue until I want to give up" approach. :black_eyed:

And as an output, I want to write a recommended maiden flight plan that is flexible enough to account for multiple airframe types (3 channel, 4 channel, bank and yank, etc). And then I want to print out this maiden flight plan and stick it in my flight box so I can review it before I take off, and hopefully learn more quickly and less painfully in the future. :cool:

So with considerable thought, both over the past few months and especially after my most recent maiden flight involved bringing home a plane in a trash bag, here are the things I would like to learn from a maiden flight. [Edits adding ideas from the group here...]

Learning Objectives of a Maiden Flight


  • All
  • Range Check - does receiver/antenna placement have any dangerous dead spots?
  • Control Check - does everything move the direction it should based on stick input? Very important do this first!! :)
  • Video Check - ensure video is recording and lens cap is off

    Fixed Wing - Maiden Launch
  • Ground handling - if applicable, does it taxi straight? how does it handle field conditions - bouncy or stable?
  • Takeoff from ground - does it track straight on takeoff?
  • Takeoff by hand launch - with a straight throw, how quickly does it gather airspeed to get to controllable flight?
  • COG / Balance validation - is it flyable or do all control inputs result in erratic behavior (tail heavy)?


    Trimming
    1) Get two mistakes high and at a comfortable speed and on mid-rates
    2) Try for straight and level passes both up and down field
    3) Trim elevator till it holds pitch hands off
    4) Trim ailerons till it goes straight hands off
    5) Go vertical with the back of the plane facing you to check for yaw struggles
    6) Trim rudder
    7) If the plane will do inverted, try rolls to both right and left. If they are not similar in speed/circumference land and look for geometry differences in the control surface movements

    Flight Experience Testing
  • Yaw authority - how effective is the rudder (if one exists) at performing a flat turn without aileron input?
  • Thrust line - Does it gain altitude or yaw with more or less throttle?
  • Stall speeds - at what throttle/speed levels does it lose lift?
  • Stall behavior - what happens in a level stall? does it fall cleanly into a dive? what happens in a stall in a bank?
  • Flap behavior - how effective are the flaps at changing the stall behavior?
  • Speed behavior - are control surfaces stable (i.e. no flutter) at max speed?
  • Deadstick behavior - how does the airframe react with all motor power cut?
  • Landing behavior - how will the airframe deal with landing approach? quickly sinking or floats forever?

    Gliders
  • Glider launch tests - start gentle glide launches, step up to DLG peg or high start with increasing power
  • Other specific flap features - CROW / Flaperons / Spoilerons

    Multi-rotors
  • Defaults maiden - starting with all default PIDs & rates
  • PID tuning - separate flight after initial control to tune PIDs
  • Rate tuning - separate flight after PIDs are happy to push rate performance
  • FPV - start LOS (Line of Sight) first before putting on the goggles

So, what other things do you test for on a maiden flight? And what kind of procedures / steps / best practices do you use to test these things?
 
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earthsciteach

Moderator
Moderator
Dang! That's a lot! I call it a success if I don't need to change my pants afterward.

The only thing I'll toss in (because I always do this :rolleyes:) is a range check prior to flight.
 

makattack

Winter is coming
Moderator
Mentor
Good list and discussion! I'll add that I do multiple maidens depending on the airframe. For FPV, I'll do a LOS maiden and a FPV maiden. For multirotors, I'll do a "defaults tune" maiden just to see if what I'll need to do for a tune, a "tuning maiden" where I'll adjust the PIDs, a "rates maiden" where I start pushing the rates and fine tuning the tune, and finally a "FPV maiden" -- sheehs, yah, that's why it takes so long for me to get multirotors in the air...
 

TexMechsRobot

Posted a thousand or more times
Good list and discussion! I'll add that I do multiple maidens depending on the airframe. For FPV, I'll do a LOS maiden and a FPV maiden. For multirotors, I'll do a "defaults tune" maiden just to see if what I'll need to do for a tune, a "tuning maiden" where I'll adjust the PIDs, a "rates maiden" where I start pushing the rates and fine tuning the tune, and finally a "FPV maiden" -- sheehs, yah, that's why it takes so long for me to get multirotors in the air...

I agree with "multiple maidens". I just built a Bug DLG and my first set of maidens will be a bunch of glide tests. Second set of maidens will be gentle launches with traditional HLG methods. Third set will be finally launching from the DLG peg with increasing power.

I think that technically, any of those could be considered the maiden but it's more of a process for some air frames.
 

makattack

Winter is coming
Moderator
Mentor
Oh, great point TexMechsRobot! Yeah, I recall my first sailplane (Flyzone Calypso) also consisted of multiple maidens similar to yours:

* Free-flight horizontal toss glide test to check CoG.
* Powered maiden with only aileron/rudde/elevator controls
* Flaps maiden to see what happens with flaps deployed at altitude
* Full house advanced maiden with crow, flaperon, spoileron, camber setup.
 

rockyboy

Skill Collector
Mentor
Great input everyone! Thanks!

I've merged these ideas back into my initial list - except for the change of pants part - that's just part of the normal / natural process :p

Any thoughts on testing for speed? I'm thinking of Plan A - fly 2 mistakes high and give it full throttle to see if it's stable and if any control surfaces start fluttering vs. Plan B - put it into a powered dive and see if control surfaces start fluttering. And I'm sort of thinking Plan B is not as good to start with here cause pulling out of a dive just increases airframe stress and chance of cratering, vs. Plan A backing off the throttle leaves the plane in a safe attitude in the air.

What about best practices for testing some of the other conditions?
 
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Craftydan

Hostage Taker of Quads
Staff member
Moderator
Mentor
I'm all for glide tests if your wing loading isn't crazy high . . . but not free flight. For an RC plane, launching FF without having good confidence you're close to right is begging for damage. I tend to control mine down, keeping in mind where the "trimmed" position is . . . then I can adjust CG and trim between glides to match. You're done when you can throw it for a glide FF. Now my FF planes . . . if they take a nose dive to the ground they tend to bounce mockingly (advantages of weighting in single-digit grams), so embarrassing, but generally not destructive.

There is a less-common glide test I like to call a "release and catch" -- get a jogging pace with the plane cradled above your head, attitude straight and level, into the wind . . . as the plane gets light in your hands, let them drop 3-6" and let the plane drop back into your hands. Rinse. Repeat. Depending how it falls, you adjust trim and balance. If it falls/pulls rolling left/right, add some roll trim. If it yaws a bit as it falls, adjust yaw trim to counter. If the nose or the tail land first, adjust pitch trim and balance. I tend to do 2-3 drops between adjustments, to make sure I saw what really happened. It's a great test, if your jogging speed is higher than the stall . . . and you've got the stamina to jog a bit.

So the nose pitches up/down . . . trim pitch or balance? Start with surfaces neutral, and if it pitches up, move balance forward. Down, give a bit of nose-up pitch. If you pick up a lot nose-up pitch, it's probably too nose heavy so move the CG back and ease off on the pitch.

Glide tests on the ground only set gross CG balance -- preferably mildly nose-heavy -- then in flight, use other tests (I prefer dive tests) to nudge it to taste.
 

JimCR120

Got Lobstah?
Site Moderator
It depends on perspective. A great maiden could be splinters and flames as long as it's someone else model.
 

cranialrectosis

Faster than a speeding face plant!
Mentor
Regardless of the type of craft or the outcome, film the maiden.

The maiden is special because you have no baseline. It never flew like that before because it has never flown. This makes troubleshooting a maiden harder than troubleshooting after a repair gone wrong.

Film the maiden so you can watch what happened in slo mo. Film the maiden so if it doesn't fly, the forum can help you with why. :)
 

Mid7night

Jetman
Mentor
Regardless of the type of craft or the outcome, film the maiden.

The maiden is special because you have no baseline. It never flew like that before because it has never flown. This makes troubleshooting a maiden harder than troubleshooting after a repair gone wrong.

Film the maiden so you can watch what happened in slo mo. Film the maiden so if it doesn't fly, the forum can help you with why. :)

1000X THIS.

Even if it's ugly and destructive, and many maidens are, you can learn from what you see. But you can only see it if you record it. Even if it's just a hatcam video, it's incredibly valuable. I have one specific baseball cap with velcro on the brim for my RunCam; it's my Maiden Hatcam set. It always looks where you look with a relatively wide field of view, so you don't have to think about framing. It's not great for the up-and-away shots, but it's perfect for takeoff and landing, which are really the more crucial (and nervous) parts of a maiden flight.
 

Crazy Goats

Active member
All very helpful posts. Thanks guys. I don't have much advice (what's a successful maiden like?) but I also suggest filming it. Thing happen so fast on the maiden, its good to have some way to go over it later.
 

makattack

Winter is coming
Moderator
Mentor
1000X THIS.

Even if it's ugly and destructive, and many maidens are, you can learn from what you see. But you can only see it if you record it. Even if it's just a hatcam video, it's incredibly valuable. I have one specific baseball cap with velcro on the brim for my RunCam; it's my Maiden Hatcam set. It always looks where you look with a relatively wide field of view, so you don't have to think about framing. It's not great for the up-and-away shots, but it's perfect for takeoff and landing, which are really the more crucial (and nervous) parts of a maiden flight.

Heheh, I do this... or at least try to... I don't post many maidens though, because... I typically forget a few things on a very consistent level:

* Remove lens cap
* Start recording
* Both of the above.

I've come back from too many maidens where I had a fully charged, empty Mobius hat cam or tens of minutes of audio only recordings with a black screen. I think the coordination required to start filming things is just too much for my pea sized cranium.

I've had many people ask why I have a camera with a lens cap on my visor as well... age can be a terrible thing...

Oh to add to CraftyDan's warning about a total free flight glide test... yes, I definitely only do that with the light wing loading planes, which for me are the whipit and umx radian. For all else, it's powered up, with control surfaces only used (no throttle). Although, I will have to add that when I first maidened my FT Versa Wing, which was my first delta wing experience with no stabilization (learned on the Delta Ray) I wasn't confident enough that I could launch it with enough force so I started the glide test launch with 50% throttle that I immediately chopped after it left my hands.
 
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Hai-Lee

Old and Bold RC PILOT
After starting out with a "It looks right! followed by Away in goes, crash, it will be alright and "Put it Away! I have progressed to a point where I can maiden almost anything.

For my own designs, (the most likely to have problems when being flown for the first time), I have developed a series of checks and tests to allow for a less troublesome maiden flight.

1. The walk around! Check for any damage, loose control horns, pushrod connections, control surface freedom of movement, Tail and wing alignment, symmetry, thrust angles, propeller condition, propeller is tightly attached and the like.

2 Electronics check including servo mounts, function throttle response and range, Battery mounting, Motor mount attachment, Motor rotation direction, and Rx range check.

3. Taxi trials if applicable though for larger models which have no landing gear I use a dolly for maiden take off though the second maiden is normally a hand launch once I know and understand the "Torque Roll" and "P" factor attributes of the design.

4. High speed ground runs with a few hops to get a feel as to when roll control is effective enough to overcome Torque roll or P factor issues.

5. a return to the pits for another physical inspection for any changes caused by the vibration and banging effects of the testing so far.

6. The first flight! A gradual increase in throttle to get a high speed ground run, (purposely held running along the ground when a dolly or undercarriage is available), followed by a gentle climb to at least 2 mistakes high. Gentle maneuvers and trimming take place and after a few circuits and the plane is trimmed I practice a few high altitude landings followed by a slightly "Greased" landing.

7. Looking at the trim settings on the plane I make minor adjustments to the push rods and the CG if required.

8. Second flight! Use the remaining battery at high altitude, testing roll, bank and other flight maneuvers getting more aggressive with each attempt. Also check Stall, Inverted flight, Roll rate, Maximum control inputs and max speed "High G" dive and climb. A few low passes and test the approach at lower speed. When battery is low a normal landing is attempted.

9. Recheck of all physical and electronic checks and either pack it away for next flying day or a new battery for its first "No Holds Barred" flight.

For a hand launched plane I follow all the above except the taxi tests where i substitute a hand launch at half throttle and gentle control inputs until the plane has sufficient flying speed where upon I slowly increase the throttle in the slow climb to reach the 2 mistakes altitude.

Following the above test/maiden methodology I have eliminated all ground loops, and sudden roll over and dive into the ground events from my maiden flying. Also eliminated have been the "OOPs I meant to attach/tighten that".

YES sadly I still occasionally crash when performing a maiden test flight but only when I miss/forget a step in the above procedure. Most maiden crashes are truly avoidable and there is only one more rule. If a plane has a problem, then going faster and higher only means a bigger hole in the flying field. Fix the problem and the plane will last a very long time. Ignore a problem and you should have a large stock of FB and plane parts for the next build.

P.S. Never test fly a model which has been sitting/cooking in the sun or in a locked parked car because the Hot Melt glue can soften and at maximum control input a hinge line sealed with Hotmelt can glue itself at maximum deflection and the servo might not have enough strength to break the glue or it might have enough strength to rip the control horn out of the surface. That plus the dreaded wing fold can be the result of being too hot though the hole in the ground is still just as deep regardless of the cause!

It works well for me!
 
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ViperTech

Member
I might have missed it but a spotter is a great help on a maiden at least for me anyway, If something is way out of trim and you have your hands full just keeping it flying, a good spotter can make trim adjustments as you concentrate on flying and help you get it back down to correct the problem. Yea three hands on the controller is crowded but if it saves the day then why not.
 

PsyBorg

Wake up! Time to fly!
For a maiden I start by checking and rechecking any hardware making sure it is all secure and that every screw, bolt, or nut has been tightened. Then I do a run up test without props to recheck motors all turn in correct direction and most importantly that when I turn off my radio fail safe kicks in properly. Then once that is all checked I will recycle power and check again then make sure the video gear is working properly by checking that VTX and the receivers or goggles are both on the same channel AND band. I think we have all been bit by that bug. Do a close up video check and see good picture only to find 20 feet away you are blind because your TX is in one band and your RX is in another with only 8-15 htz difference between them. Last I do a quick check on the air frame looking for cracks or bad gouges or anything in general that could be a weak spot. All that BEFORE even leaving the house.

Once I get where I am flying maiden or not I ALWAYS do a quick test hover LOS and then a small run around the area I plan to fly. Take today for instance. That's how I found out I now have a random intermittent ESC failure and my quad is not reliable to actually fly LOS or FPV. At first it acted like a fail safe only when facing a certain direction which to me indicated a broken antenna. Then it happened right after arming and motor number 2 stopped. Looked things over and could not get it to repeat so did another test hover and started to head to where it dropped before and it fell down again not 10 feet away. That ended the day and will need much more in depth inspection.

One last thing I check before actually flying is the area I am going to fly. Sometimes kids will come out to watch or to play on the play set. Some times when at the park people are out walking or simply short cutting thru the field I fly. I usually pause a bit to see their intentions as some will come over and talk others will hang out in one place and watch. Others will let their dogs run off leash to go say hi to strangers thinking everyone enjoys their dog jumping up on them when they can't see or even notice they are there.

My main rule of flying..If there is a person there I count them as an idiot until proven different by their actions. I expect them to do something stupid like walk out into an obvious race course to look at the flags without so much as a hello. Sorta like watching a deer on the side of the road.. is it going to leave, stay there, or run out in front of my car.
 

rockyboy

Skill Collector
Mentor
I might have missed it but a spotter is a great help on a maiden at least for me anyway, If something is way out of trim and you have your hands full just keeping it flying, a good spotter can make trim adjustments as you concentrate on flying and help you get it back down to correct the problem. Yea three hands on the controller is crowded but if it saves the day then why not.

I initially hated trimming, and frankly wouldn't do it on a lot of my models when I was first learning to fly. Taking my hands off the stick long enough to touch the trim tab resulted in really scary flying maneuvers.

Then @hildaflyer helped me trim out a wing at FTFF16 and while 3 hands on the controller was a little interesting, the flying experience was so much improved after proper trimming I was just amazed.

Then he told me about cross trimming. This is the practice of mapping the trim tabs from the right hand gimbal to the left gimbal tabs, and vice versa. What this gives you in practice is the ability to use the left hand to push the trim tabs next to the left stick to adjust elevator and aileron trim rates - while your right hand stays firmly on and in control of the right stick.

This has completely changed my flying world - seriously, the single best thing I learned about flying at FF. I've since gone back and updated the programming on all my models to enable cross trimming, and now trimming doesn't scare me any more :)
 

Tench745

Master member
Depending on how in depth you want to get, I would suggest looking over Homebuilt test flight materials for an idea of how to prepare for a maiden, and what to look for when you do finally fly.
There's the Homebuilt and Ultralight test flight document from the FAA https://www.google.com/search?q=AC+90-89a&ie=utf-8&oe=utf-8
and several articles on the topic.
http://www.avweb.com/news/features/Homebuilt-Flight-Testing-Conducting-the-First-Flight-223346-1.html
https://www.eaa.org/en/eaa/aviation-communities-and-interests/homebuilt-aircraft-and-homebuilt-aircraft-kits/next-steps-after-plane-is-built/testing-articles/stage-one-making-preparations-for-flight-testing
http://www.pilotfriend.com/experimental/build_16.htm

And a video from the FAA

A key thing to remember is: success starts before you ever get to the field.
-Be current: have you had enough practice to not dumb-thumb
-Know how this plane will be different from other planes you've flown
-Be well rested
-Be willing to walk away and try another day if things don't seem right
-Fly in an area appropriate to what you're doing (paved or grass, big enough area, no radio interference, etc.)
-Have only necessary personnel: No spectators! They're just an invitation to show off or distract you.
 

SlingShot

Maneuvering With Purpose
1. The walk around! Check for any damage, loose control horns, pushrod connections, control surface freedom of movement, Tail and wing alignment, symmetry, thrust angles, propeller condition, propeller

There is a lot of quality info in this thread. I would just like to add that the walk around starts on the workbench. Build a square and balanced plane. After that take the time to do a proper and thorough setup. Make sure the control surfaces are all zeroed and set your throws conservatively.ro
 

rockyboy

Skill Collector
Mentor
Maiden Flight Plan for 3 Channel 'Bank and Yank' plane

It looks like I'll get a chance to take my Banana Bugatti out for a maiden flight this weekend, so based on the learning objectives in the first post, and all the great input, I've written up my flight plan for the first two 'maiden' flights.

The objective is to run a shakedown of basic flight characteristics and do the types of maneuvers and steps that will get me the best information to make whatever adjustments are needed and avoid the dreaded Lawn Dart event.

This plan is specific to the 3 channel 'bank and yank' airframe - there are other things I'd want to do with a plane with more controls and features.

I'm going to print this out and see if I can follow it and avoid this maiden flight turning out like my last one. It included a 'take trash bag on walk of shame' step. :black_eyed:

Pre-Flight
- Radio Range Check
- Control surface movement direction & binding check
- Control linkage check
- Hinge flex check
- Battery mounting check
- Motor / Prop mounting check
- Glide test w/ radio on

Maiden Flight 1
- Video camera on
- Lens cap off
- Reset flight timer
- Hand launch
- Gentle climb to safe altitude
- Partial power turns right and left
- Reduce throttle to a stall from high level flight
- Simulated landing at safe altitude - practice stall speed & approach turns
- Landing

Post flight
- Check battery / motor / esc temperature
- Check battery level & time
- Check control linkages & hinges
- Check overall airframe rigidity
- Write up flight performance notes

Maiden Flight 2
- Video camera on
- Lens cap off
- Reset flight timer
- Hand launch
- Full power climb to safe altitude
- Full power turns
- Loops
- Rolls
- Deadstick
(more advanced maneuvers if behaving well)
-- High power dive
-- Hammer head
-- Immelmann
- Simulated landing at safe altitude
- Landing

Post flight
- Check battery / motor / esc temperature
- Check battery level & time
- Check control linkages & hinges
- Check overall airframe rigidity
- Write up flight performance notes


If I'm lucky I won't have to write up the 'Items to Repair' list like I usually do. :cool:
 
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rockyboy

Skill Collector
Mentor
Yeah, so that last story ended with the Banana Bugatti getting snagged by a monkey in a tree. Still there as far as I know. :black_eyed:

Anyway, I wanted to come back to this thread as I found an excellent, detailed write up on trimming RC planes on a website dedicated to building with balsa (love this site - read every page!)

Here's a link directly to his bit on trimming:

http://www.balsaworkbench.com/?page_id=125

To quote a couple key steps (in case something horrible happens and we lose his site from the interwebs)...

VERTICAL THRUST ANGLE

This is the easiest step in the trimming process. Most planes have a vertical thrust angle specified on the plans, but usually a bit of fine tuning is required.

Fly your plane at full speed, trim for level flight, then cut the throttle. If the plane surges downward when you cut the throttle, adjust the thrust angle downward. Of course the plane should be expected to drop off a bit when you cut power, but it shouldn’t surge downward.

On the other hand, if the plane seems to float up when you cut power, you have too much down thrust and should shim the engine upwards a bit.

And here are a couple other interesting points....

The next step is to find the correct side thrust angle. Set the throttle at full speed and trim the controls for level flight. Then cut the engine to idle.

If the plane turns left when you cut the power, you have too much right thrust. If it turns right when you cut the power, you need more right thrust.

Shim the engine mount accordingly, re-trim the plane in flight, conduct the test again, adjust shims again, test again, etc, until your plane doesn’t turn when you cut the throttle.

And just one last section I'll quote (I hope he doesn't mind). Please go check out his article and website for more details... lots of good stuff over there!

Your next step is to find the correct balance between rudder and aileron trim. Let’s say the plane was always turning left, so you want to trim to the right. Should you trim rudder or ailerons? If you trim the wrong one, you’ll notice unusual performance whenever you do anything other than fly straight and level.

Take your plane to a comfortable altitude at high speed. Cut the throttle to idle and then pull the elevator back to make the nose of the plane go straight up. Pretend you’re going to do a loop, but you cut the power before you pull up, and you never go over the top. Just go up.

If your plane goes up and yaws to one side, you need to trim the rudder the other way. When you return to straight and level flight you will probably need to trim the ailerons to compensate for you rudder trim change. Repeat this test until the plane goes straight when you cut the throttle and pull the nose vertical.