Member Support

  • Advertisement
0

Modifications to Aircraft and Performance Data

Technical Questions, Know How, Equipment, Tools......

Modifications to Aircraft and Performance Data

Unread postby TriPacer » Wed Jul 01, 2015 4:54 pm

Hey everyone - after being reminded of Kevin's accident and looking further into it, I was wondering what you all do (if anything) to establish new performance values for your seaplanes.

For example, The Force has a stall kit, VGs, 184hp (nominal) engine, etc... Highly modified from the 150hp 172K it used to be. I generally fly off the 172's POH numbers for Vx, Vy, Vs, etc. I know it's relatively easy to go out and do some power off stalls to establish the new Vs values, but how about Vx, Vy, etc? I'm sure there are straightforward ways to do this, but I suppose I've never given it the thought I should...

Sometimes we certainly operate at the edge, so it's good to be really sure of where that edge is...
TriPacer
Owner Of The Force
Image
From Minnesota, where men strangle bears and children fly helicopters!
User avatar
TriPacer
Supporting Member
Supporting Member
 
Posts: 484
Joined: Thu Jun 09, 2011 11:43 pm
Location: Twin Cities, MN

Re: Modifications to Aircraft and Performance Data

Unread postby RKittine » Wed Jul 01, 2015 6:23 pm

Most STCs come with new data regarding performance and limitations, but since most older planes have been modified in other ways, the data may not be that applicable. When ever I added anything, V.G.s Dropping Tips, even an external camera mount with camera or antenna, I would slow flight the plane, do a series of stalls, steep turns, check for best glide and checks speeds verses power settings. Same thing with aircraft for IFR use. When I start with a new student in their aircraft, I use the American Fliers, IFR Power / Configuration chart to Performance Chart the aircraft. That includes Power and Flap Settings for Straight and Level, 3-500 FPM climb and Decent, approach configuration level, descending with approach flaps at the recommended final approach speed for that aircraft for both precision and non-precision approaches. Tells you a lot about the aircraft, saves a lot of time when flying IFR knowing what power and pitch will give you the desired effect, but most of all it allows you to see how much variation there is in even the same make and model aircraft with the same approximate options and modifications. Having flown many model seaplanes, I would do the same thing to establish things like power and final speed for step taxis, correct power, pitch and speed for glassy water etc. Again this will change from one plane to the next even when the same model with the same pilots (weight / CG) on board.

I have never flown Glenn's J-4, but I have flown Robert Evert's and Bob Ferenzi's, both on EDO 1320s and I used different power and speed setting for each.

Bob
SUPPORTING MEMBER

Bob
West Nyack Aviation, L.L.C. New York, New York - East Hampton, New York & Warwick, New York 631.374.9652
rkittine@aol.com WA2YDV
User avatar
RKittine
Supporting Member
Supporting Member
 
Posts: 4760
Joined: Wed Apr 28, 2010 11:02 am
Location: Manhattan and Sag Harbor, New York

Re: Modifications to Aircraft and Performance Data

Unread postby jjbaker » Wed Jul 01, 2015 6:55 pm

This will sound terribly cheesy and not well thought out, definitely not like something sober people would write.

After being reminded of Kevin's accident (which was so terribly poorly investigated by T.C.) I had some beer from Belgium and Germany to reset my hard-drive. His loss is one of the 32 I count, one of the very few which still hurt me personally, almost two years after the crash.

What I find most disturbing about Kev's accident is that he apparently committed a complacency, rookie mistake when landing on a confined water-body in pretty much inclement weather. For me personally, the aircraft and the mods play a minor role, because a good seaplane pilot flies by the seat of their pants - IOW's with his/her ASS. I know, deep in me, that Kev was such a pilot. Like my grandfather used to say: He is a "flying with his ass" kind of pilot. But, on this particular bad hair day, he was too sure to be able to handle it. Poof. Done. Shit! This fortunately usually happens so quickly, you won't have much time to regret your moves and actions. In fact, I think most of those who get hit with something of such magnitude, fight it to the bitter end - which is why I think that no pilot ever dies doing something he/ she loves. Getting killed is no fun, sorry.

A good pilot (in my book) can feel out what he is allowed to ask from the airplane in any given circumstance. Fail any instrument, the engine or anything, really - and a good pilot will still conclude the flight on the ground with everyone on board intact and walking. Sometimes, just sometimes, we tend to think that we can master or teach Physics and Nature a lesson. We fly "on the edge". For commercial pilots this is a normal, for us weekend and hobby warriors, its a special day we either get to talk about, or we don't. Many, or most don't, cuz if they could, we would think twice before converting our husbands or wives to widowers.

I remember ferrying a modified Mooney sometime in the 90's, shortly after I got my license. There was no complex or high performance endorsement, just an owner tossing me the keys to an airplane he thought I could fly. Fact: My PPL-A allowed me to fly single engine, piston powered aircraft up to 2000KG MTOW, and the Mooney fits that bill. So, I sat in that plane on a hot summer day, reading the POH. Goal: "How do I.....?" I had read and studied for a while, when a 75 year old instructor stopped by. His words: "Feel it, when it's ready to fly you will know, because the plane tells you everything you need to know." I kept reading for a while, before deciding to fire the plane up and go. Guess it worked.

At the end of the day, determining exact performance data isn't what floats the ship. The plane was built and flew in dozens of configurations, with dozens, or no mods at all. If it was brought back to mother earth by anyone before you (in its current configuration), then it deserves to be brought back to mother earth, intact, by you.

Kev (and many others I knew and lost as parts of a statistic) wasn't an "off the shelf pilot". He worked hard for what he knew and could do and he was highly regarded as a responsible and knowledgeable, skilled pilot. He was an excellent instructor and friend. Neither was he afraid to share what he had learned, nor was he afraid to ask, in fear of looking dumb. He asked me for help on his website less than half a year before he died and he asked for others opinions before making decisions. He talked me out of my worst frustration with this forum, when I was a mouse-click away from shutting the site down. I miss this guy, but I am in a bad spot, like many website owners who have "members". There's lots of people I've come to respect and value - and the clock is ticking.

Here's my tip for anyone who flies any airplane with modifications that change the behavior of the aircraft:

You are not a test pilot.

Unless you are (*you'll be alone, hopefully*) you have a responsibility towards the people who fly with you, to know EXACTLY what this airplane can and cannot do. In some cases your employer has a responsibility to make sure you know and can handle any particular airframe, before you carry people around in it. 85% of accidents are investigated in perfect CAVOK. You owe it to the people you leave behind, to be on your very best F'ing game, anytime you fly. Don't let them have doubts about your commitment and common sense. Kevin had both, he just made a mistake.

I understand the pressure involved in commercial flying, not as a bush pilot, but as a commercial pilot who was expected to decide on behalf of people who trust their life to him. Quite a feeling, much different from being a driver, for example. There is no shame in a go around, there is no shame in declining any flight, for almost any reason. Its ALL you. There is no shame in being alive and on the ground rather than wishing for the same to be true while flying marginal conditions in a marginal airplane for less than good reasons. Is a life depending on your being on time? Are we at war? No? Then slow the F down and think before you act.

I remember and and live by the rules of the three E's. Environment, Equipment and Ego.
Surviving inclement weather (Environment), with a plane you don't fully know quite yet (Equipment) requires humility (Ego) to be survivable.
Any two of those E's can be geared against you and you still stand a chance to walk away.

Accidents we get to witness or experience are an opportunity for us to pause and think.
Have we lost the edge? Should we take a break? Are we asking for trouble? I don't know a single good pilot who's never asked that question.

Who do we ask? Our dead comrades, who supposedly know? I wish I could talk to Kevin today!
He'd have answers and pointers I didn't expect. He'd be brutally honest and kick my ass. I'd prefer that over the hole he left.

Moral of the story: Fly that plane. Get to know it. Feel it. Let it show you what it can and cannot do...but, at a safe altitude!
ACCEPT the boundaries. These are YOUR boundaries and these boundaries differentiate between a beating heart from one that has stopped.

Sorry for bringing an emotional spin to a factual data topic. Think about it - and tell your thoughts.

--- No long post without answering some questions ---

I learned this from a AG Pilot:

Vx = Best Angle (Best possible altitude gain over any given distance)
Vy = Best Rate (Best ft/min climb rate, as in getting up high quickly)

Both are good speeds. The best speed is the one that allows you to finish the flight without any sudden stoppage or hitting shit.

For a float plane or seaplane - anytime I am operating in an area where V' Speeds are of importance, one of my E's is already geared against me. I will make a CONSCIOUS EFFORT and adjust my EGO right away, rather than waiting for the equipment to give me further trouble. The circling takeoff (or, using other terminology: extracting the maximum of positive control energy out of the plane, while still caught on the water) or the beloved "safety pass" (as in: overflying any intended field for landing, while under positive control and power) will help determine a go from a no go call. Both circumstances are shaped by JUDGEMENT.

Your mileage may vary.
User avatar
jjbaker
Owner/ Admin
Owner/ Admin
 
Posts: 5846
Joined: Thu Apr 22, 2010 4:46 pm
Location: Germany

Re: Modifications to Aircraft and Performance Data

Unread postby RKittine » Wed Jul 01, 2015 7:27 pm

JJ, Much of what you say is true. I have felt for sometime, that their comes a time, then your experience level will allow you to fly pretty much any similar aircraft. Around 1,000 hours I have seen many pilots that can use the markings on the airspeed indicator of a totally new aircraft to them and wrangle it into the air and back onto the ground without bending anything. At least in good conditions with no emergency happening. I remember my first experience flying an early Cessan 310. Had never flown one and helped someone by ferrying one from Northern Illinois to Southern Illinois. Used about 3,000 feet of runway to land it, but without incident. I then got some instruction in the 310 and found with the correct procedure (basically power setting with flap changes only until I flew in onto the runway I could get one down in well under 1,000 feet. So much depends on the environment.

Yes, with a lot of experience, you can sense when a plane is ready to fly (Take offs are easier than landings in my opinion), but what if that feeling comes at 2,000 feet when you are trying to get out of a 1,500 foot field and clear an obstacle at the end of the runway.

Knowing how a plane performs in advance, will help determine how well it may work in a specific situation / environment.

Have a few more brews for me.

Bob
SUPPORTING MEMBER

Bob
West Nyack Aviation, L.L.C. New York, New York - East Hampton, New York & Warwick, New York 631.374.9652
rkittine@aol.com WA2YDV
User avatar
RKittine
Supporting Member
Supporting Member
 
Posts: 4760
Joined: Wed Apr 28, 2010 11:02 am
Location: Manhattan and Sag Harbor, New York

Re: Modifications to Aircraft and Performance Data

Unread postby jjbaker » Wed Jul 01, 2015 8:11 pm

That's a great response, Bob.

I talked about this with a LAN Inspector after the death of my grandfather. "Experience compensates for other issues". He taught for 64 years without being killed, so I guess he must have done something right. A highly experienced pilot may solve a situation, even though most of the parameters are geared against a successful outcome.

It is my opinion (really personal opinion, not dependent on my beer consumption) that WE set boundaries prior to every flight.
I know my grandfather did and he set me up to do the same. In the beginning, I probably "rote level repeated" what he had taught me, but the older I got, the more I adjusted the rules to myself. We take more risk, naturally, because it didn't kill us last time.

Look at the high density altitude go around. Look at the short field takeoff at MGTOW, look at the confined area takeoff or landing.
We can juggle those numbers until we like them, or we can decide to set conservative parameters - or change the setup.

This may mean to leave freight or pax behind, wait for a better density altitude time or set "bench marks" for when we wish to be airborne.
If I have 2000 feet, I want to have made judgement about being able to fly the damn plane (or not!) at 1000.

The more experienced we get, the more we fall victim to thinking that this is just another flight, so my attempt to give an answer to Brian's excellent question was driven by the realization that numbers are good on paper and that even the best POH planning assumes (1) perfect conditions, (2) perfect airplane and (3) a test pilot manipulating the controls. We need some buffer zone to stay alive. I hope this makes sense for those who'd like to calculate their exact situation, compared to those who simply try not to hit stuff. My POH said I could safely perform the takeoff or landing, nevertheless apparently something didn't work out.

Where/ When do I stop pushing???

Determine V Speeds for yourself. Chances are they are different for every single configuration or setup out there.
Realize that - when you really need Vx or Vy to save the day - you should already be well out of your comfort zone.
User avatar
jjbaker
Owner/ Admin
Owner/ Admin
 
Posts: 5846
Joined: Thu Apr 22, 2010 4:46 pm
Location: Germany

Re: Modifications to Aircraft and Performance Data

Unread postby RKittine » Thu Jul 02, 2015 6:55 am

Thought not to the same extent, we are however in some ways Test Pilots on every flight we take. Setting those parameters and doing a good job on the preflight, eliminates much of the TESTING, but the conditions can change in seconds as we have all learned.

When I first got my Instrument Rating and what I tell my IFR students to do, is once rated, set your own personal minimums much higher then the legal ones and start learning how to really fly IFR without an instructor next to you and with lots of room to spare. I started out filing on days when the ceiling was at a minimum of 3,000 feet so that I could go up, get into or through IMC and then make an approach(s) that had IAPs of over 3,000 and then fly them. Little by little my experience level grew as well as my confidence and I was soon ready to tackle an ILS to minimums as well as VOR and NDB approaches to minimums. I still teach NDB approaches as it really teaches how wind works and the skills to deal with it. Easy to get hooked on the Coupled Garmin 530 with WAAS.

Bob
SUPPORTING MEMBER

Bob
West Nyack Aviation, L.L.C. New York, New York - East Hampton, New York & Warwick, New York 631.374.9652
rkittine@aol.com WA2YDV
User avatar
RKittine
Supporting Member
Supporting Member
 
Posts: 4760
Joined: Wed Apr 28, 2010 11:02 am
Location: Manhattan and Sag Harbor, New York

Re: Modifications to Aircraft and Performance Data

Unread postby TriPacer » Mon Jul 06, 2015 11:39 am

Thanks guys - these are really well-thought-out responses and I appreciate the time taken to write them. As I wrote this post, I realized I was talking as if there was a "Bob's way" and "Jason's way", but that's not my intent - there are very important, complementary points to absorb from each of your answers.

Being a scientist, I tend to take an analytical and process-oriented approach to many things. In some regards, I feel as if going out and re-establishing these values would make everything safer, as if knowing those values would somehow make me a better pilot, and I can see a lot of value in taking Bob's approach in testing. Not that these data points are inconsequential or unimportant, but the statement:

Realize that - when you really need Vx or Vy to save the day - you should already be well out of your comfort zone.


is something I resonated with. Maybe, to some extent, it's better that I don't know them with precision. As of today, I do feel out the plane and how it's behaving, and react quickly when something doesn't feel or look right to me (i.e. gives me that ping in the pit of my stomach). Although I have only 200 hours and a LOT to learn, I do feel as if "flying with my ass" was drummed into me from the very beginning. I had a great team of primary instructors, so I thank them for that. They taught me to build in as much safety margin as possible, and I think it's served me pretty well so far.

A good example might be this past weekend. I was set to take some friends up north and was going to be at gross weight. I've never taken off from the base's lake (relatively small) with a full load, and it stuck in my craw that this would be the first time, especially on a hot July afternoon. So I just met the friends at a much larger lake. As it turns out, I could have taken off from the seaplane base and been fine, but I was happy with my choice. To Bob's point, it would be different with a different load at gross, too (different cg, different temperature, etc...).

As with most things in life - finding a balance between rote memorization of the performance data and feeling your way through the flight is probably the best solution.
TriPacer
Owner Of The Force
Image
From Minnesota, where men strangle bears and children fly helicopters!
User avatar
TriPacer
Supporting Member
Supporting Member
 
Posts: 484
Joined: Thu Jun 09, 2011 11:43 pm
Location: Twin Cities, MN

Re: Modifications to Aircraft and Performance Data

Unread postby CFII » Mon Jul 06, 2015 10:20 pm

I expect flight students to know the numbers as does the FAA however when I catch them acting like they can trust the numbers it's a guaranteed event coming up that I'll stage to prove otherwise. Few things irk me more than a pilot figuring takeoff distances for DA and Gwt out of a PoH for intended application on a 30+ year old aircraft, especially with runway surfaces that aren't truly known.
CFII
Gold Wings II Member
Gold Wings II Member
 
Posts: 1318
Joined: Thu Jun 09, 2011 1:13 am
Location: Seattle Amphibion

Re: Modifications to Aircraft and Performance Data

Unread postby RKittine » Tue Jul 07, 2015 6:44 am

As I have been doing more and more tailwheel instruction, we are now talking aircraft that are over 60 years old and have not watched their diet and usually have gained a lot of weight and have engines that are more tired them most. Up at Island Bob's takeoffs are from a channel with a lot of physical markers close by, road sign when most start their run, overhead wires to stay under etc., that allow you to really get a good idea how take off performance is in many configurations and wind situations. Since there is also a road that runs right next too and very parallel to the take off channel, it is easy to go and measure things like distances to correlate with time.

Bob
SUPPORTING MEMBER

Bob
West Nyack Aviation, L.L.C. New York, New York - East Hampton, New York & Warwick, New York 631.374.9652
rkittine@aol.com WA2YDV
User avatar
RKittine
Supporting Member
Supporting Member
 
Posts: 4760
Joined: Wed Apr 28, 2010 11:02 am
Location: Manhattan and Sag Harbor, New York


Return to Technical & Aircraft Talk, Building & Restoration

Who is online

Users browsing this forum: No registered users and 4 guests