Flight Test Interview Questions?

[sphan]

Hi All,
I'm a new guy trying to get in the business. I interviewed for a junior FTE position, but didn't get it ( :-( ). After beating myself up for a few days, I'm trying to put together a gameplan to reapply in 3 months time (hopefully the position will still be open and I didn't make too much of a fool of myself). I'm going to work on my interview skills (keeping my cool during questioning and not blabber) as well as my technical knowledge.

I'd like to poll the audience for technical interview questions that you have seen or think would be appropriate. As important as the answer is the process as to how you determine that answer. Maybe this test bank will help others trying to get into the business as well.

Here are some questions that I encountered:
1.Q. Is a helicopter rotor disk parallel to the ground during hover
A. Use F = ma to find the answer

2. Q. You have a new aircraft. How can you get Calibrated Airspeed from Indicated Airspeed
A. Formation flying with a aircraft that has calibrated data or fly between landmarks (need to take wind into account by going upwind, downwind, and crosswind)

3. Q. Pitot- static tubes are usually close enough to the airplane that some disturbances occur. How do you get pure, unadulterated V_infinity?
A. Test planes usually drag a line behind them that is far enough from the plane that it can be considered essentially V_infinity. I said a long pitot static far outfront could work

4. Q. You are in a 2g turn, what is the estimated minimum speed needed to maintain this?
A. Use F = ma, relating the g load to the lift equation.

5. Q. What is the air-speed velocity of an unladen swallow (African)?
JK. They didn't ask me that

Any questions would be much appreciated. Good luck to anyone else trying to be an FTE.

[Genghis the Engineer]

I'm an old guy, been in the business some time, and have interviewed a few people for this sort of role over (cough) years. On that basis, here are a few thoughts:-

Hi All,
I'm a new guy trying to get in the business. I interviewed for a junior FTE position, but didn't get it ( :-( ). After beating myself up for a few days, I'm trying to put together a gameplan to reapply in 3 months time (hopefully the position will still be open and I didn't make too much of a fool of myself). I'm going to work on my interview skills (keeping my cool during questioning and not blabber) as well as my technical knowledge.

I'd like to poll the audience for technical interview questions that you have seen or think would be appropriate. As important as the answer is the process as to how you determine that answer. Maybe this test bank will help others trying to get into the business as well.

Here are some questions that I encountered:
1.Q. Is a helicopter rotor disk parallel to the ground during hover
A. Use F = ma to find the answer
F=ma is at the root of just about any solution in physical sciences, so that doesn't really answer the question.

The answer in this instance will depend a lot on wind, but there's also such a thing as coning angle. I suspect that the interviewer mostly however wanted to see if you'd adequately read around the subject and could think on your feet.

Prouty's multi-volume (1, 2 or 3 volumes, depending upon which edition - 2 at present) "Helicopter aerodynamics" would be a very good introduction here.

I'm guessing that a constructive interviewer will ask, if you give a good "zero wind" answer, "what about when there's a wind ?".

2. Q. You have a new aircraft. How can you get Calibrated Airspeed from Indicated Airspeed
A. Formation flying with a aircraft that has calibrated data or fly between landmarks (need to take wind into account by going upwind, downwind, and crosswind)
Personally I use GPS for a low performance aircraft rather than landmarks which is a rather "early 20th century" solution. For higher performance aircraft, formation, tower fly-bys or trailing statics are all "industry standard" solutions, depending upon what the aircraft is, and what capability you have available. AC23-8 or equivalent documents should cover this quite well.

Incidentally, I'd always like to see a candidate who knows the IAS/CAS/EAS/TAS/GS relationships. If they haven't got that, then there may be no hope!


3. Q. Pitot- static tubes are usually close enough to the airplane that some disturbances occur. How do you get pure, unadulterated V_infinity?
A. Test planes usually drag a line behind them that is far enough from the plane that it can be considered essentially V_infinity. I said a long pitot static far outfront could work

A trailing static is intended to get rid of static errors, not pitot errors. A long leading pilot is a fair suggestion used on quite a few aircraft. Look up a kiel probe as well.

The truth is, you can't achieve free stream conditions, you can only get the errors small enough (or known enough) to make the results useable.

4. Q. You are in a 2g turn, what is the estimated minimum speed needed to maintain this?
A. Use F = ma, relating the g load to the lift equation.

At 2g, L=2W. L=0.5.Rho.V^2.S.Cl.

Rho and Cl won't change. So, to double lift, you need to multiply V by sqrt(2).


5. Q. What is the air-speed velocity of an unladen swallow (African)?
JK. They didn't ask me that

Any questions would be much appreciated. Good luck to anyone else trying to be an FTE.

Buggered if I know either, but it's a great "see if the blighters can think through something not in the textbooks" question.

My favourite is usually to take a model of a flexwing microlight that lives on my desk and ask the interviewee to explain how you achieve a level turn with it. I have absolutely no expectation that they know the answer - as Rogallo wings aren't, so far as I know, taught on any degree course - I am interested in their thought processes, not their knowledge. If I ever get a hang-glider pilot to interview, I'll probably have to ask something about gyroplanes instead.


Suggested bedtime reading:-

Stinton - Flying Qualities and Flight testing of the Aeroplane.

FAA - AC23-8 and AC90-89

Cooke and Fiztpatrick - Helicopter Test and Evaluation.

Gratton - Initial Airworthiness.

Prouty - Helicopter Aerodynamics

Croucher - JAR Professional Pilot Studies


All live on my office shelf or hard drive, and are reasonably maths free "go to" books for basic understanding of any stuff I don't normally deal with, or am doubting my memory and understanding.

Another standard question I usually use if interviewing somebody for an airworthiness job is to derive the V-N diagram for a sample aeroplane and give me the main V-speeds.

For more advanced FTE positions, I'd also anticipate CRM / teamwork type questions. I great one I was asked when being interviewed for a job I didn't get at Learjet once was "okay, you're FTE on a prototype flight, the TP does something stupid that endangers the aircraft - what are you going to do about it ?". [I think that my answer was good, they laid off 2000 people and put a recruiting freeze on a week after my interview, that's my story and I'm sticking to it.]

On my ETPS entrance panel 20 years ago, I was asked how the SR71 achieved directional stability. That's a fun one.

Best of luck,

G

[ICT_SLB]

sphan,
Having worked in Flight Test for the best part of 25 years, firstly congratulations on getting an interview! Genghis has answered the technical side of your post (I suspect he's the author of one of the recommended books) but for a more general one, there should have been several links to previous threads. Unfortunately it looks like they have been purged as the links no longer work - they were fairly old.
You must have had some - possibly a lot - of experience to have obtained your interview so if this seems old hat please forgive me. From my experience inside a civilian test organization (I survived G's lay off), FTEs are recruited from within the FT Engineering organization unless they have already been one in the military and even then it may not be a slam dunk unless they have some mutual acquaintances. In short, if you are aiming for a civilian FTE position, I would apply for a job in the Flight Test group using whatever degree you have and then see what opportunities are available. Best of luck!

[sphan]

Thanks very much for the reply. I'm jaw dropped impressed! I really appreciate the very in depth responses to the questions I posed as well as the reading suggestions. I really enjoyed the anecdotes too. Among the reasons why I'd like to do this instead of build drones. You guys have cooler stories

FYI, I grew up in the town where Francis Rogallo was born (Sanger, CA!). I'm not a hang glider pilot, but have a special affinity towards his work. If I were sitting in your office, I would mention shifting the weight to the inside of the turn. This would cause a moment about the longitudinal axis and shift the lift vector towards the turn. You would most likely have to increase overall lift to keep from losing altitude. In a hang glider, this is pushing the nose of the wing up/ moving the weight back. Even though it's a flexible wing, I don't think there is so much wing warping that drag on the in side is the predominant factor.

Do I pass? I know nothing of gyroplanes other than they were big in the 30's.

As for the SR-71 question. I'm going to have to think about that a bit. Since the F-16 was the first fly-by wire plane, that means the SR-71 had positive directional stability. It had very small vertical stabilizers that seems insufficient for stabilizing the long nose (small tail volume). Remembering the equation, it seems that the aerodynamic center would have to be pretty far forward for positive stability, but that's not the case since the wings were so small. Unless the large fillets moved the AC up....

[sphan]

Thanks for your reply. I have to admit my friend worked at the company and recommended me, so I kind of jumped the queue.

I don't have much real world experience, and I did a PhD not where my heart lay, but where the funding was. I think they liked my private flying experience, and my RC work. The place I interviewed at was a Silicon Valley startup who is doing really cool manned flight stuff for the personal aviation world.

In addition to kicking butt in the technical knowledge, I was going to wow them by back engineering the handling qualities of the Amazon Prime UAV if it were flown by a real pilot. I think that would get there attention.

Thanks again for the reply and wish me luck!

[Genghis the Engineer]

I suspect he's the author of one of the recommended books)

And knows the authors of three others - all of which were written in response to a perceived need. Someone has to write them, and the world would be a poorer place without :)

Thay said, apart from the FAA ACs, all my recommended books are pretty expensive. Use a library if you can.

G

[Genghis the Engineer]

You're welcome sphan.

Re: The Rogallo wing - don't forget that the Rogallos were a husband and wife team. The era in which they started out - it was normal for the man to take all the credit, but in reality Gertrude was probably every bit as accomplished a researcher as Francis. Your description isn't bad for first stab, although actually the aeroelastic deformation of the wing is very important once you get to know them well.

Re: SR71 - think vortices.

Re: PhD - having a PhD is certainly a Good Thing, as it is ultimately a research qualification, and those research skills are transferrable to other fields of endeavour. I've noticed over the years that here in the UK employers (except universities) are under-impressed by PhDs as they don't really understand them, whilst in the US employers are over-impressed by PhDs, for much the same reason. Ultimately, you have a set of valuable research skills and should be exploiting those and selling them as part of the package.

Gyroplane stability and control is a complete black art, but I do know a few people who have made a career of studying them. I was drooling over this last weekend at the UK's Flyer show - it's a new design yet to fly. I have a suspicion that it will prove a very poor aircraft, but by god it's beautiful. Gyroplane design and development is actually in the ascendancy, and there have been some very impressive designs over the last decade or so. One of these days I know I'm going to succumb and have a go.

http://bulldogautogyro.com/wp-content/uploads/2015/05/20150418_085658-640x480.jpg

Continued best of luck,

G

[John Farley]

The first question the Commandant of ETPS asked me in 1955 was "Why do you want to be a test pilot" In my opinion that is the best first question to ask anybody being interviewed for any job.

[sphan]

Genghis,
It is indeed a beautiful gyrocopter! Really clean lines. Reminds me of the Bugatti 100P in terms of its aesthetics

http://roa.h-cdn.co/assets/cm/14/47/980x551/546b307d8e88b_-_bugatti-100p---profile-lg.jpg

May I ask why you think it would be a poor aircraft to fly? I'm not at the point where I can look at a plane and start gauging its characteristics, but hope to be. I imagine the taildragger configuration makes for more difficult ground handling, and the empennage looks a little undersized, but nothing else sticks out to my novice eyes that would suggest it would be a bad aircraft.

[ICT_SLB]

sphan,
Despite what the Lawn Dart designers would like to claim, the F-16 was not the first FBW aircraft.

[Genghis the Engineer]

May I ask why you think it would be a poor aircraft to fly? I'm not at the point where I can look at a plane and start gauging its characteristics, but hope to be.

Tiny rudder, unclear about the ability to match vertical CG to propeller thrustine, and that long cantilever from behind the cockpit to the rotor hub just frightens me.

Also, there's a lot to be said for generating the noise and propwash downwind, not into wind, of the cockpit - viz all flexwing microlights and pretty much all modern gyroplanes.

I hope I'm wrong - it's beautiful, and I'd love to see some fly sooner than later, and you definitely want it to be as good to fly as it looks.

G

[ICT_SLB]

Genghis,
One replica of the Bugatti 100p has already flown: https://youtu.be/8yZdrvgV4qE?t=10

[212man]

Since the F-16 was the first fly-by wire plane

Surely Concorde was the first production FBW aeroplane?

[sycamore]

GTE, who makes that autogyro..? got any other photos...?surprised there`s no stick dangling from the rotorhead,ala Cierva...

[Genghis the Engineer]

I know as much as is on their website, which isn't much - and a colleague (boffin, Scottish, rotary background, you can probably guess who I mean) has indicated that the design is mostly conducted by somebody ex-army with a limited academic-engineering and flight mechanics background.

Bulldog Aircraft from BJJR seeing is believing (http://bulldogautogyro.com/)

This photograph I took at Telford gives you an idea of the rudder, controls and cockpits...

https://scontent.xx.fbcdn.net/hphotos-xtl1/v/t1.0-9/r270/12313520_1060174817334888_9178006403767589841_n.jpg?oh=c0bac a983d2d7f61e4531f6d18897566&oe=56E5221A

G

[Genghis the Engineer]

Genghis,
One replica of the Bugatti 100p has already flown: https://youtu.be/8yZdrvgV4qE?t=10

And crashed (gently to be fair) on landing after its first flight !

G

[Jhieminga]

It did a lot better on its second flight though! https://www.facebook.com/TheBugatti100pProject/videos/871712069572600/