Jet turbine reliability

The HPH Shark takes 28 liters of Jet A1 + 4% Aeroshell 500. That will
give about 55 minutes cruising at 80-90 knots... The technique is not
climb and glide, rather dolphin flying... pulling up in any residual
energy and in notime you have gained quite a lot of height... It works.
Typically The Shark Jet will do 170km on a tank. The FES version will do
about 100km, whilst the Shark MS (Self Launcher) will do over 300km
on a tank...

Craig

At 08:30 05 June 2015, wrote:
"Gobble as well as gulp...with Jet A at +/- $5 a gallon and AeroShell
560
at $15 a quart that works out to north of $100 to fill up the JS-1"

Well......you could certainly calculate a worst case scenario like that.
But as 11USG of Diesel / 2-stroke (4%) oil mix is flight manual
approved,
this may be a more commonly employed option.

(US prices: 10.6USG @ $2.70 + 0.42USG & $20) is $37.

Glider pilots: Tighter than a fish's a....... :P

At 10:10 05 June 2015, Craig Lowrie wrote:
The HPH Shark takes 28 liters of Jet A1 + 4% Aeroshell
500. That will
give about 55 minutes cruising at 80-90 knots... The
technique is not
climb and glide, rather dolphin flying... pulling up in any
residual
energy and in notime you have gained quite a lot of
height... It works.
Typically The Shark Jet will do 170km on a tank. The FES
version will do
about 100km, whilst the Shark MS (Self Launcher) will do
over 300km
on a tank...

Craig

Interesting thread but surely if you are proposing to spend
£100K on a jet self-launch the cost of the fuel is a minor
matter? For some people the range will be the overriding
factor, if you are not in this category starting reliability might
be more important.
Jet and two-stroke technology: probably will start?
FES/Electric technology: almost certainly will start?

Ask this question: when pick up a Hoover do you think: Will
it start? When you pick up a two-stroke strimmer or chain
saw do you think: Will it start?

David W

On Friday, June 5, 2015 at 3:15:06 AM UTC-7, Craig Lowrie wrote:
The HPH Shark takes 28 liters of Jet A1 + 4% Aeroshell 500. That will
give about 55 minutes cruising at 80-90 knots... The technique is not
climb and glide, rather dolphin flying... pulling up in any residual
energy and in notime you have gained quite a lot of height... It works.
Typically The Shark Jet will do 170km on a tank. The FES version will do
about 100km, whilst the Shark MS (Self Launcher) will do over 300km
on a tank...

Craig

At 08:30 05 June 2015, wrote:
"Gobble as well as gulp...with Jet A at +/- $5 a gallon and AeroShell
560
at $15 a quart that works out to north of $100 to fill up the JS-1"

Well......you could certainly calculate a worst case scenario like that.
But as 11USG of Diesel / 2-stroke (4%) oil mix is flight manual
approved,
this may be a more commonly employed option.

(US prices: 10.6USG @ $2.70 + 0.42USG & $20) is $37.

Glider pilots: Tighter than a fish's a....... :P


For reference, an ASH26E uses about 2 liters for a warm up and climb to 2500 ft agl, and will do 680 Km on its 16 liter tank (according to the book - never had a retrieve that long!). To do that you climb to altitude limits then fold the engine and glide, and repeat as needed. Is the climb performance on a jet significantly better so that the climb and glide technique improves retrieve range over a level cruise?

Climb and glide with the Jet is NOT optimal...

The best speed for the Jet engine is probably over 200 knots (!)....
and whilst this is not possible, the faster the better... so after
briefly climbing away from a field, it is better to accelerate to 80-90
knots and then dolphin-fly, varying speed in accordance with any
residual lift (these is always some)... This technique will produce
the best range...

Craig

At 19:02 06 June 2015, jfitch wrote:
On Friday, June 5, 2015 at 3:15:06 AM UTC-7, Craig Lowrie
wrote:
The HPH Shark takes 28 liters of Jet A1 + 4% Aeroshell 500.
That will=20
give about 55 minutes cruising at 80-90 knots... The technique
is not=20
climb and glide, rather dolphin flying... pulling up in any
residual=20
energy and in notime you have gained quite a lot of height... It
works. =
=20
Typically The Shark Jet will do 170km on a tank. The FES
version will do=
=20
about 100km, whilst the Shark MS (Self Launcher) will do over
300km=20
on a tank...
=20
Craig
=20
At 08:30 05 June 2015, wrote:
"Gobble as well as gulp...with Jet A at +/- $5 a gallon and
AeroShell=20
560
at $15 a quart that works out to north of $100 to fill up the
JS-1"

Well......you could certainly calculate a worst case scenario
like
that.=
=20
But as 11USG of Diesel / 2-stroke (4%) oil mix is flight
manual=20
approved,
this may be a more commonly employed option.=20

(US prices: 10.6USG @ $2.70 + 0.42USG & $20) is $37. =20

Glider pilots: Tighter than a fish's a....... :P


For reference, an ASH26E uses about 2 liters for a warm up and
climb to
250=
0 ft agl, and will do 680 Km on its 16 liter tank (according to the
book -
=
never had a retrieve that long!). To do that you climb to altitude
limits
t=
hen fold the engine and glide, and repeat as needed. Is the climb
performan=
ce on a jet significantly better so that the climb and glide
technique
impr=
oves retrieve range over a level cruise?

Op zaterdag 6 juni 2015 21:02:52 UTC+2 schreef jfitch:
For reference, an ASH26E uses about 2 liters for a warm up and climb to 2500 ft agl, and will do 680 Km on its 16 liter tank (according to the book - never had a retrieve that long!). To do that you climb to altitude limits then fold the engine and glide, and repeat as needed. Is the climb performance on a jet significantly better so that the climb and glide technique improves retrieve range over a level cruise?

Yes. The higher the thrust/weight ratio is, the more it pays off. Best CLIMB speed for example for a 450 kg ship and a 800N jet is way above 100 kts.

For highter thrust/weight ratio's, fuel efficiency goes up too; a dolphining flight can get similar mileage to a decent car, even with the typical fuel burn of such a jet (70 kg/hr for the 800N AMT).

Some comments from actual experience:
I have flown both self launching and sustainer gliders (Schemmp & AS), and now own a JS with turbine. I have no experience with the FES, although I have seen it ground run. For this post I will mostly ignore the FES, although I think it is an excellent system, save for the minimal drag which is a large concern for contest pilots. Plus, our national electicity supplier are all out of electricity and options, so charging might be difficult at times 😄 ( just kidding)

Operation:
The jet is by far the easiest to deploy, start, run, shut down and retract. It is a simple 3 step process. Turn on the master switch, switch the turbine to run, wait for turbine to spool up, and add power by turning a knob, all on one 57mm LCD instrument. The software can actually spool up the turbine to max rpm automatically, elliminating step 3. Shutting down is equally effortless. Switch off, and the controller does the rest. It waits for the turbine to cool, and then retracts automatically. Once retracted, you can turn the engine master switch off.
Safety: I have deployed the jet sucessfully from 150' agl (thats feet agl). Normally, I switch the master on at about 1000' agl. I extract the engine at 600', but do not start it yet. At 250' agl I switch on the jet, and it is at idle rpm at 150-160' agl.
Compared to the AS wankel engine, which I would start that at 600'. The solo sustainer I would normally start at 1000' agl. Both the wankel and turbo engines have a significantly higher workload than the jet.
In all of these scenarios I obviously have a landing field available in case of a failed start. I have had failed starts, and subsequent outlandings, with all three systems. No system is 100% reliable.
Initially (I had one of the early installations ) the reliability was about 60%. M&D and JS have however ironed out the initial problems and reliability issues (expected with any new system). I dont keep exact track, but I have not had a failed start or problem for the last year, except a glowplug glitch on the ground before flight for the last 18 months, so reliabilty is now a small worry.
Use
I have used the jet 5 times now in the last 100 cross country flights, with the longest retrieve about 220km straight line through dead air, I climbed from about 1000' agl in light rain, flying at about 70kts ias. I continued climbing up to about 11000' amsl, or 6000' agl and switched off the jet. I burned 30 liters of fuel. I estimate that a 380-400km range is possible in dead air. The rain stopped after the first 5km.
General:
Maintenance is all but non existant, apart from the ocasional wipe off to get rid of dust, and a visual pre flight inspection. I had the actuator that extends the engine replaced (under guarantee). Refueling is very easy. I prefer using Jet A1, as I think it is a more efficient fuel, and it smells better 😄. The fuel filter gets cleaned or replaced during the annual inspection.
Noise in the cockpit is not intrusive, even when wearing no earplugs or a headset. The radio can be heard clearly through the normal speakers, as can the vario. Noise on the ground during a flypast is less than the traditional internal combustion engine. It gets noisy when doing a stationary ground runs, but no more than a prop driven self launcher.
When the jet has not been in use for an extended period, a ground start before flight is advisable to purge the fuel supply of air, ensuring an immediate start in the air.
As the glow plug and fuel pump needs constant current during operation, it is advisable to have your battery charged up.
The jet goes from master on to full power in 45 seconds. Idle rpm is 30 000 rpm, and full power delivers just under 100k rpm. I normally limit the rpm to 95k. At 95k rpm the fuel burn is 40liters per hour, and fuel capacity is 42 liters. Fuel burn drops to about 35 liters per hour at 9000' amsl. Exhaust gas temprerature is about 650 deg celcius at full power. Temperature change on the vertical tail skin is minimal, even on the ground as the engine is slightly offset.
On the test aircraft, during the endurance test, which was flown for an hour above 20 000' amsl and at 110 000 rpm continously, a blade did separate from the rotor. The blade was contained in the housing with no other damage to the engine or glider. This specific engine had run all the certification tests before throwing the blade. I dont know how many hours it had, but it was significant.
I can honesly say this is the best system if you want to avoid landouts. The airfield I fly from mostly has a tug available, so I dont need a self launcher. Apart from the simplicity and efficiency of the jet, the biggest factor is the sheer joy of playing around with the jet running.

OG--thanks for your input.

What is Standard Operating Procedure regarding leaving jet fuel in tanks between flight? Should you always leave the tanks full or do you pump all the fuel out after flight and refill before next possible use?

Once you buy Jet A, how long would you keep the fuel before you would consider it "bad"?

What is Jonkers/M&D warranty regarding jet and ECU?

I leave the fuel in the tank, but replace it every 3 months, should it not be used in that period. I am not sure what Jet A1 specs say about shelf life, but I think this is about right.
Seeing as the jet is still in evaluation/developmental phase, I am not actually sure what the warranty is. That being said JS/M&D stands behind the product. My actuator was replaced at no cost. Barring obvious misuse/abuse I am sure they will be more than reasonable with any latent defect. But I dont speak for either of them, so dont quote me😉

On Sunday, June 7, 2015 at 9:28:54 PM UTC+1, OG wrote:
I leave the fuel in the tank, but replace it every 3 months, should it not be used in that period. I am not sure what Jet A1 specs say about shelf life, but I think this is about right.
Seeing as the jet is still in evaluation/developmental phase, I am not actually sure what the warranty is. That being said JS/M&D stands behind the product. My actuator was replaced at no cost. Barring obvious misuse/abuse I am sure they will be more than reasonable with any latent defect. But I don't speak for either of them, so dont quote me😉

There is a 2012 UK General Aviation Safety Information Leaflet that advises a "shelf life" of 3 months for Avgas and 6 months for Jet A1. It advises keeping tanks 90% full to reduce deterioration or water contamination.

On Sunday, June 7, 2015 at 12:29:34 PM UTC-7, wrote:
OG--thanks for your input.


Once you buy Jet A, how long would you keep the fuel before you would consider it "bad"?

Self launch and turbo gliders sometimes have low fuel throughput, and this gives HUMs (hydrocarbon utilizing microbes) a chance to thrive in the fuel/water interface - and there will always be some moisture. HUMs have been an issue for Stemme and Schleicher owners, as the HUMs excrete acid that can corrode metal parts and they attack fuel lines and clog filters.

The shelf life of Avgas (at least a year) and Jet-A (even longer) in the US is not the issue, it's keeping the microbes from contaminating fuel and fuel system. Many of us use BioborJF (the JF is for jet fuel for which Biobor is certified - though it works in gasoline too). It only takes 4 ml per 5 gallons for initial dose and then 2 ml per 5 gallons after that.

Note that Biobor also has a "MD" and "EB" version for diesel and ethanol laced fuels, though the "JF" version is the only version I'm aware of that includes antimicrobial ingredients.