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Author Topic: How I maiden airplanes  (Read 5952 times)

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Online Frank v B

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How I maiden airplanes
« on: February 21, 2013, 08:03:08 pm »
Andy Hoffer asked me to publish the steps for maidening an airplane after last night's Pilot's Meeting. 

I have been asked to maiden about 25 airplanes a year for the past 20 years.  This list is a very conservative way to maiden airplanes since my only mission is to bring the plane down in one piece.  I have only failed twice.*  This assumes the basics of radio/pushrods/servos/left is left/up is up etc. are fine.

1) Pre-Flight 
- Nose heavy CG.  Take the forward CG of a given range and move it forward.  Note: some CG's on plans are significantly wrong!! (eg. Sig Wonder)
- make the elevator throw conservative and the aileron significant.  Do not have significant throws on 2 axes.  The plane will corkscrew.
- lots of rudder, especially on WW2 models (Spit, Mustang).

Watch out:
- for Spitfires and Mustangs.  Take what you think will be a conservative elevator throw and then reduce by 1/3.
- Cubs - make it significantly nose heavy.

2) Taxi test- do a high speed taxi run to see:
- if it tracks straight
- if it wants to take off.
- if you have enough rudder throw.

3) Take-off.
- Line up for take-off from the farthest downwind point of the runway (max runway distance)
- punch it to full throttle (if electric, a fast advance if IC) and commit to the take-off

4) Speed before altitude.  As soon as the plane breaks the ground, level off at about 4' and pick up max speed before giving "up" elevator.

5) Make the first turn at significant altitude (2 mistakes high) and turn slowly.

6) Do only 2-3 circuits at altitude and then prep for landing (no rolls, no loops, no low speed stuff, no retracts, no flaps).

7) Land at higher than normal speed... just in case, land at a shallow angle just after the apron.  Slowly throttle back once you are 2-3' off the ground and feed in up elevator until it settles down.  Note: do not cut the motor during the landing, keep the prop spinning to keep prop wash going over the wing and tail feathers.

7+1)** Landing: cut the throttle immediately (esp. a tail dragger) just in case of a nose-over, to protect the speed controller/motor

9) Take the airplane apart (wing off) Look at all the connections and screws (motor screws, servo screws, landing gear, hinges).  Centre the servos on the trims you landed with.  Get ready for a second flight.

10) Second flight:  Take off, go two mistakes high and check:
- low speed
- stall
- flap
- retractable landing gear

Note: I never touch these areas in the first flight

11) Go home and celebrate!!!     

Hand launch airplanes:
same as above but:
- have a friend hand launch it for you.  Avoid solo maidens at all cost.
- give the elevator at least 3 clicks of "up" trim.  No lift on the wing until you get speed.
- launch by aiming at an imaginary spot on the horizon 100 feet in front of you.  Do not launch at an upward angle until you have several successful flights under your belt.

This is by no means authoritative.  The main message is be conservative on the first flight and take about 5 flights to get to know your airplane.  My most complicated plane is a 4 IC engine 5 foot span plane.  I fly it on a basic 4 channel transmitter without dual rates on purpose to reduce the mistakes (wrong dual rates, wrong switches, no slaving, no mixing).  Fight human error.

Happy flying

Frank van Beurden

* two crashes:
- a .40 size Great Planes Decathlon after suffering a broken aileron servo wheel.  Sorry Tony
- A student's Alpha 40 after suffering a 2.4 brownout.
I completely re-built both these airplanes.  Significant damage to both

** can't punch in the number "8" because it brings up a smily face.
« Last Edit: February 21, 2013, 08:10:47 pm by Frank v B »


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Offline sihinch

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Re: How I maiden airplanes
« Reply #1 on: February 21, 2013, 09:32:43 pm »
This is really, really helpful Frank! Thank you so much for taking the time to write it up and share it with us.

I'll try to remember all this when I maiden my Hunter!!!!

Offline thehaze

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Re: How I maiden airplanes
« Reply #2 on: February 21, 2013, 09:35:11 pm »
Good stuff!
Takeoffs are optional. Landings are mandatory.

Offline Bobmic

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Re: How I maiden airplanes
« Reply #3 on: February 21, 2013, 09:55:48 pm »
Hi Frank,
Why is it required to reduce the elevator throw this much and increase ailerons ?
I understand the risk of pulling up tooth and stall but what if there is not enough throw - wouldn't it cause a bigger problem?
Second question - why is increased aileron throw required?
Thx
Bobby

Online Frank v B

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Re: How I maiden airplanes
« Reply #4 on: February 21, 2013, 11:15:48 pm »
Bobby,

re: elevator for Mustangs and Spits- require less throw because these airplanes are very short-coupled (distance between the trailing edge of the wing and the leading edge of the stab).  Because we overpower the airplanes, very little elevator travel will have huge impact on the pitch of the airplane.  Fred's airplane last night was the exact opposite (very long tail moment).
Elevator travel in general should be enough to take off.  All I am trying to do is achieve flight and have a safe landing.  If the travel is not enough, it just won't take off.  It usually doesn't take a lot of throw to gently fly airplane 3 circuits and land.  Then dial in the right throw for the second flight.

Carefully watch the crash videos, especially from Florida.  Half the crashes are because the plane has way too much elevator travel.  Those are the airplanes that porpoise while landing.  These are the airplanes that have been maidened before so I really don't get their stupidity. 


re: lots of aileron.  I fly twitchy airplanes and have no problem handling a lot of aileron travel.  It allows me to quickly correct a problem along the roll axis.  Roll axis problems are usually harder to overcome because it usually means a combination of a dive and inverted flight and that is an express ticket to re-kitting an airplane.
This significant aileron travel has saved several airplanes, including that 4 meter power glider I talked about last night.  If you have a lot of travel on both aileron and elevator it is an invitation for trouble.  The plane will corkscrew and then do a powered falling leaf into terra firma while you try to (over)correct.

Once you have maidened the airplane you can dial it back to where you want it.
All I am trying to do is to survive the first flight and give myself the best chance.

A lot of this stuff is personal based on experience.  I have seen lots go wrong on model airplanes and I am trying to protect myself from the overpowering attraction model airplanes have to eating dirt. ;D

Frank

« Last Edit: February 21, 2013, 11:43:59 pm by Frank v B »
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Offline Bobmic

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Re: How I maiden airplanes
« Reply #5 on: February 22, 2013, 07:51:37 am »
Thank you Frank,

These are great tips, thank you for the excellent summary.
 ....unfortunately I missed Wednesday's meeting as I thought it was planned for Saturday :(

Offline Ededge2002

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Re: How I maiden airplanes
« Reply #6 on: February 22, 2013, 08:15:23 am »
It was planned for Saturday we just couldn't wait?

A great presentation Frank. Always good to have reminders too
Yea 400W/lb should about do it.. But wouldn't a nice round 500 be better?

Offline flying saucer

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Re: How I maiden airplanes
« Reply #7 on: February 22, 2013, 03:32:20 pm »
Great tips!

I would also add that you check battery voltage post-flight, in order to get a rough idea of possible flight times on your power system.
 

Offline Michael

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Re: How I maiden airplanes
« Reply #8 on: February 22, 2013, 04:01:16 pm »
For the record, there are other techniques.  :)

I usually fly first flights with ailerons set on low rates and with at least 20% exponential.

The worst thing that ever happened with these settings was that I was unable to do a roll.



Generally I find (major) manufacturer's recommended settings to be good.

Michael

Online Frank v B

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Re: How I maiden airplanes
« Reply #9 on: February 22, 2013, 06:04:37 pm »
Michael,

You mentioned exponential.  I finally programmed the first one of my planes last summer with exponential out of the 150 planes I have owned.  Expo is just not on my mental checklist.  It should be.  It is very helpful especially for 3 D planes... but then I don't do 3D.... except just before I crash. ;D

Frank
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Offline Ededge2002

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Re: How I maiden airplanes
« Reply #10 on: February 22, 2013, 07:01:19 pm »
Actually Frank although I'm no expert at 3D I've found that its helpful to know how in troubled flight conditions such as flying slightly tail heavy aircraft.
Yea 400W/lb should about do it.. But wouldn't a nice round 500 be better?