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Thursday, April 28, 2011

Are we using the right planes/Engines for the job?

Submitted by Jonathan Porter
As part of our approvals process in Ghana we are required to undertake regular training and to keep our 'engineering certificates' up to date. consequently, Patricia and Capt Yaw, went to Europe for training. Since the training was the week after AERO Friedrickshafen (Europe's Oshkosh), we went a few days early, accompanied by Paul for one of the days, and met with other engineers from around the globe at this event.

Doing what we do, it is important to remain abreast of the latest developments and to assess if we are on track and if we should change directions. So, before entering the halls of fame and salesmen's verbal spewaged, we empty our minds of pre-conceptions and start afresh, thinking outside the box.

The first hall was gliders. Beautiful machines crafted like Godesses of the air, smooth and silky, able to glide horizontally fifty times the height they have achieved in still air. Lightweight batteries and the e-machines with electric 'get me home' engines. Many have suggested that such an approach may have a place in Ghana. So, we make the assessment.

1. Mostly they are composite aircraft. Hard to identify damage to the airframe (often hidden by the gel coat)

2. Large wingspan makes off field landing spots hard to find.

3. Not able to land at the busy airports due to inablity to 'follow instructions' when gliding in, often in thermal conditions, and unable to clear the runway under own power (if motor glider maybe).

4. Undercarriage light or one wheel, not strong enough for an off-field landing.

5. COST. Over Euro 100,000 for the sleek machines. They are so high tech that they really are for the connisseur.

Verdict: Not for our operations.

We see the new fleets of Autogyros - magnificent machines, hybrid plane-helicopters. There performances are amazing, and the newer designs eye catching. However, they lack load carrying capacity, proven life on the long rotor blades and, most importantly, there is no working legislation for them in Ghana at this time. Remember, we started the concept of what we do now in 1994! It takes time! So, much as these machines are showing promise:

Verdict: Not for our operations at this time.

Helicopters took another hall. It is a simple thing with helicopters - 'if you have to ask the price, you cant afford it'. If they cost less, drank less and went further, I would order one tomorrow.

Verdict: Not for out operations at this time.

Next we see the plethora of 2 seat aircraft. These made the biggest display segment. Most of them powered by Rotax 912 engines. We see a wonderful little bird, low wing but with a tall undercarriage. Paul and Patricia were drawn to the irridescent pink plane, begging to be admired and stroked under the cowling.

Bog-eyed looks into the cockpit revealed the latest in glass TV screen instruments, and the cruise speed magnifilourous! We saw some sporty looking Formula One look-alike machines that looked fun, and tube and fabric as well as tube and cloth machines boasting incredible lives of their coverings - and of course strengths that would make Popeye feel as if he needs more spinach! There were plenty of aluminium machines too, but their construction methods varied considerably, as did their layouts.

Of course, to make a plane look nice is easy, to make a plane fly nice is harder, to make a plane fly nice, be strong and easily maintained is the tough part. So, we take the criteria that makes it work at our end. Let us start by ruling out:-

1. Avoid composites (apart from fairings, tips, cowlings and small parts). Reasons above.

2. Avoid welded tube constructions. Hard to inspect and although we have Argon Gas Welding (thanks to the Stieber family), it is not yet a time where we can say we have the expertise to handle, inspect and maintain such construction methods in the bush.

3. Avoid fabric and dope covering - too many issues with temperatures and storage of dope. There are some modern fabrics, but there are still issues with our facilities, temperatures, humidity and appropriate application use at this time.

4. Tube and cloth, provided for light applications still are valid, but appear to be going out of fashion on the marketplace, at least looking at the offerings at AERO. None of the tube and cloth aircraft on display came close to the X-Airs that we currently use (do remember we have special thicker cloths on our machines than the standard offerings).

5. Avoid tail-draggers. With the strong winds nasty tendancy to swing around on you. Plus issue of low hours pilots and prop strikes.

6. Aluminium is good, but it needs to be able to be built using simple tools and have full plans available to make parts as needed in country. Rules out certain machines.

7. Low structural strength. For example, seeing an engine held on with 4 x M6 bolts on a popular brand.
Of course, they all CLAIM massive strength, easy flying, and speeds beyond the light-barrier, but one look at a machine below skin deep values, and you can see what you are getting into! Some are sleek and fast, some are sturdy and slow, but what makes it suitable for 'bush work'?

We need/prefer

1. High wing, braced struts, preferably two per wing with jury struts.

2. STOL capabilities.

3. Aluminium construction. Preferable with a corrosion resistant and flexible aluminium.

4. Solid construction methods that are easily carried out in rural Africa.

5. Full plans.

6. Established company behind the design.

7. Felxibility in build adaptations (drop hatches, stowage systems, etc)

8. Tricycle gear

9. Good prop clearance

So, we are down to a few machines, of course we are hunting the 2 and 4 seat category. The head and shoulders winner is still, way ahead of the pack, the Zenith CH701, CH750 and CH801 machines. Hands down. With all of the many companies out there, there really is only one that offers the machines, design, support, materials, construction method etc that fit our needs.

Verdict: WE are with the best airframe provider on the market (Zenith) for our applications, and little seems likely to change that, since most are not seeking the 'bush' and 'STOL' approaches, rather 'sleeky and speedy'. So, yes, we have made the right choice of airframe.

Now, to engines. If popularity decides it for the 2 seat aircraft, it is the Rotax 912. If proven reliability is the criteria, it is still the 912. If a company with extensive engineering expertise, strength and security of their 'establishment' is the key, the Rotax 912 still wins.

VERDICT: We use only Rotax 912 on our 2 seat aircraft, so we did good from the outset there too!
For the four seater, I have to say that we struggle still. We have the Superior XP360 which is better suited to our operations than the original Lycoming O360, and fully parts compatible, but the market needs a better 180/200Hp engine. Until that point, we are confident that the XP360 (re-entering availability later this year) is our best option at this time.

VERDICT: We are using the best offering at this time, but the market needs to change. This is a 1950s design of engine - it is bulky, thirsty and heavy, but it is what it is and does the job.
So, we pat our selves on the back and get back into the workshop to maintain and build as we can, finances permitting, the aircraft we need to change lives, one flight at a time...

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