Jet Glider Sparrowhawk

OK, what the heck. How about a superlight, turbine powered,
short wing, aerobatic, under $40K aircraft that'll
do 100 knots under full power, burn 5 gal/hr at 50 knots
in level flight, and climb at 500+ ft/min gulping
20 gallons/hr?

Prepare for SWAGs (Scientific Wild Ass Guesses)...

Here's what I gathered from

www.usamt.com

www.windcraft.fi/pik27/perf/performance.htm

www.windward-performance.com

www.accurate-automation.com

The AMT engines will provide
20 Newtons of thrust (about 4lbf) for one hour with 1 gallon of JetA.

The Sparrowhawk, with a turbine engine extended, has drag of
maybe 100 Newtons at about 50 knots (this is a guess from the
PIK 27 site and windward, and assuming 60lbs fuel on board,
and the extended engine doubling the drag).
Sustained level flight at this speed requires 5 gal/hr.

At 100 knots, the Sparrowhawk should drag 400 Newtons, which
is 20 gal/hr. Or, the Sparrowhawk can climb at 500 ft/min
with the same fuel consumption.

Assuming we have about a 10 gallon tank (gimme some slack here,
yeah, JET A is 6.84 blah, but whatever...) we can climb at
full power for 30 minutes at 50 knots, or cruise at 100 knots
for 30 minutes in level flight, or cruise at 50 knots for
two hours.

This allows (based on published Sparrowhawk gross weight)
a 170# pilot and 30# of engine+accessories + 10 gallons of fuel.

If one wishes to keep it an "ultralight", the tank can be 5
gallons instead (and a 30# heavier pilot) with halved range.

So we get a 170# pilot with a 100NM range or 12,000 ft of
climb, or a 200# pilot with a 50NM range or 6000 ft of climb.

This also assumes two AMT-450 engines (400 Newton max thrust)
or one AMT-1700 (880 Newton max thrust) throttled way back.



I'd believe my guesses are accurate within a factor of two for
everything. If fact is worse than guess, 250 fpm climb for 8
minutes or 15 minutes of cruise at 50 knots is pretty
pitiful. On the other end, 1000 fpm or 120 knots for
an hour is pretty great.

The harder questions a
How to mount the thing?
Will it fit?
Where does the fuel tank go?
Weight and balance?
How about all that heat?
Who wants to fly it first?
Can it take off from under 2000 ft?
Who's got the cash?

Mark James Boyd wonders about "turbinizing" the SparrowHawk:

The harder questions a
How to mount the thing?
Will it fit?

The fuselage behind the cockpit is just as large as a 15 meter glider,
because pilots aren't available as "ultralights". The space is empty,
because the gear is fixed and the control hookups are directly behind
the seat. I'm sure Greg could design a simple mounting system for the
engine(s). There is already a hole in the top for access to the optional
BRS system.

Where does the fuel tank go?

Perhaps under the seat back, like the PIK 20 E, or in wing tanks (SN 002
- the company aircraft - has tanks; I don't know about the other ones).

Weight and balance?

This stuff is all close to the CG, so it shouldn't be a problem. Light
pilots might need some nose weight, I suppose.

How about all that heat?

The carbon pre-preg is cured at 230 deg F (the glider doesn't have to be
painted white - pick your own color!), so it would be much less of a
problem than the conventional low temperature cured, wet layup used by
most manufacturers.

Who wants to fly it first?

Probably the designer!

Can it take off from under 2000 ft?

Get a bigger engine if it doesn't.

Who's got the cash?

If you do, give Windward Performance a call...
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Eric Greenwell
Washington State
USA

Scale up a BD-5J a little bit, make it's flight characteristics tame
enough for a reasonably competent pilot to handle and give it enough
power and fuel to make for a really kick "tail" fun aircraft for zipping
around the air in and I bet you could sell a bunch of them.

Mark James Boyd wrote:
OK, what the heck. How about a superlight, turbine powered,
short wing, aerobatic, under $40K aircraft that'll
do 100 knots under full power, burn 5 gal/hr at 50 knots
in level flight, and climb at 500+ ft/min gulping
20 gallons/hr?

Prepare for SWAGs (Scientific Wild Ass Guesses)...

Here's what I gathered from

www.usamt.com

www.windcraft.fi/pik27/perf/performance.htm

www.windward-performance.com

www.accurate-automation.com

The AMT engines will provide
20 Newtons of thrust (about 4lbf) for one hour with 1 gallon of JetA.

The Sparrowhawk, with a turbine engine extended, has drag of
maybe 100 Newtons at about 50 knots (this is a guess from the
PIK 27 site and windward, and assuming 60lbs fuel on board,
and the extended engine doubling the drag).
Sustained level flight at this speed requires 5 gal/hr.

At 100 knots, the Sparrowhawk should drag 400 Newtons, which
is 20 gal/hr. Or, the Sparrowhawk can climb at 500 ft/min
with the same fuel consumption.

Assuming we have about a 10 gallon tank (gimme some slack here,
yeah, JET A is 6.84 blah, but whatever...) we can climb at
full power for 30 minutes at 50 knots, or cruise at 100 knots
for 30 minutes in level flight, or cruise at 50 knots for
two hours.

This allows (based on published Sparrowhawk gross weight)
a 170# pilot and 30# of engine+accessories + 10 gallons of fuel.

If one wishes to keep it an "ultralight", the tank can be 5
gallons instead (and a 30# heavier pilot) with halved range.

So we get a 170# pilot with a 100NM range or 12,000 ft of
climb, or a 200# pilot with a 50NM range or 6000 ft of climb.

This also assumes two AMT-450 engines (400 Newton max thrust)
or one AMT-1700 (880 Newton max thrust) throttled way back.



I'd believe my guesses are accurate within a factor of two for
everything. If fact is worse than guess, 250 fpm climb for 8
minutes or 15 minutes of cruise at 50 knots is pretty
pitiful. On the other end, 1000 fpm or 120 knots for
an hour is pretty great.

The harder questions a
How to mount the thing?
Will it fit?
Where does the fuel tank go?
Weight and balance?
How about all that heat?
Who wants to fly it first?
Can it take off from under 2000 ft?
Who's got the cash?

In article ,
Mark Zivley wrote:
Scale up a BD-5J a little bit, make it's flight characteristics tame
enough for a reasonably competent pilot to handle and give it enough
power and fuel to make for a really kick "tail" fun aircraft for zipping
around the air in and I bet you could sell a bunch of them.

Hmmm...the things that make it work well for an ultralight
glider are lack of regulation, low stall speed, low wing loading,
light weight, and slick airframe.

At 500 lbs, a notional Sparrowhawk with two AMT-450s
would accelerate at .12 g's (2 knots/second), to 40 knots
in 20 seconds using 1200 feet of runway. Assuming wheel
friction and drag make this figure double, under 2400
feet of runway is still respectable.

But if we increase the stall/rotation speed (BD-5), the
runway requirements really increase dramatically. Plus
the huge investment to design a whole new aircraft. And
in the end it ISN'T a glider, so that sucks... ;(

A fabric ultralight with a very low stall speed is another
excellent application, but would have a very limited
speed range, depending on the wing used. Some folks go for that,
though, so that might work for them.

Can it take off from under 2000 ft?
It looks like something around this figure. The
low rotation speed really helps in this regard.

Keep in mind that even experimentals have a lengthy
fly-off and FAA supervision process. If it can be kept
an ultralight, that leaps over these problems.
This may not be possible (254 lb empty weight is ok, but
the 55 knot top speed limit is a problem per part 103).

Mark James Boyd wrote:
At 500 lbs, a notional Sparrowhawk with two AMT-450s
would accelerate at .12 g's (2 knots/second), to 40 knots
in 20 seconds using 1200 feet of runway. Assuming wheel
friction and drag make this figure double, under 2400
feet of runway is still respectable.

Wouldn't that be (500/(45+45) = 0.18 g's ? Or 3.4 knots/second to 40
knots in 10.4 seconds, and about 330 feet? So doubling is only 600 feet.

Using one engine, 0.09 g's gives 1.7 knots/sec, 21 seconds to 40 knots,
and 640 feet, doubled to 1280. With all due respect to Mike B, I might
be happy with one engine.
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Eric Greenwell
Washington State
USA

Eric Greenwell wrote:
Mark James Boyd wrote:
At 500 lbs, a notional Sparrowhawk with two AMT-450s
would accelerate at .12 g's (2 knots/second), to 40 knots
in 20 seconds using 1200 feet of runway. Assuming wheel
friction and drag make this figure double, under 2400
feet of runway is still respectable.

Wouldn't that be (500/(45+45) = 0.18 g's ? Or 3.4 knots/second to 40
knots in 10.4 seconds, and about 330 feet? So doubling is only 600 feet.

I avoided the math and safe-sided the heck out of it and
got a way too big figure. Thanks for the extra work

Using one engine, 0.09 g's gives 1.7 knots/sec, 21 seconds to 40 knots,
and 640 feet, doubled to 1280. With all due respect to Mike B, I might
be happy with one engine.
Eric Greenwell

For self-launch, perhaps, but for 100 knot level flight,
or 500 fpm climb, 200 Newtons (45 lbf) may be not enough.
I haven't done the disciplined math for this, nor
do I know the actual drag in Newtons of the Sparrowhawk.
I suppose this can be calculated rather than SWAGed based
on weight and the shape of the polar, eh? Any takers?

been done.. either APIS or Silent.. check out their web page..

BT

"Mark James Boyd" wrote in message
news:40043f30$1@darkstar...
OK, what the heck. How about a superlight, turbine powered,
short wing, aerobatic, under $40K aircraft that'll
do 100 knots under full power, burn 5 gal/hr at 50 knots
in level flight, and climb at 500+ ft/min gulping
20 gallons/hr?

Prepare for SWAGs (Scientific Wild Ass Guesses)...

Here's what I gathered from

www.usamt.com

www.windcraft.fi/pik27/perf/performance.htm

www.windward-performance.com

www.accurate-automation.com

The AMT engines will provide
20 Newtons of thrust (about 4lbf) for one hour with 1 gallon of JetA.

The Sparrowhawk, with a turbine engine extended, has drag of
maybe 100 Newtons at about 50 knots (this is a guess from the
PIK 27 site and windward, and assuming 60lbs fuel on board,
and the extended engine doubling the drag).
Sustained level flight at this speed requires 5 gal/hr.

At 100 knots, the Sparrowhawk should drag 400 Newtons, which
is 20 gal/hr. Or, the Sparrowhawk can climb at 500 ft/min
with the same fuel consumption.

Assuming we have about a 10 gallon tank (gimme some slack here,
yeah, JET A is 6.84 blah, but whatever...) we can climb at
full power for 30 minutes at 50 knots, or cruise at 100 knots
for 30 minutes in level flight, or cruise at 50 knots for
two hours.

This allows (based on published Sparrowhawk gross weight)
a 170# pilot and 30# of engine+accessories + 10 gallons of fuel.

If one wishes to keep it an "ultralight", the tank can be 5
gallons instead (and a 30# heavier pilot) with halved range.

So we get a 170# pilot with a 100NM range or 12,000 ft of
climb, or a 200# pilot with a 50NM range or 6000 ft of climb.

This also assumes two AMT-450 engines (400 Newton max thrust)
or one AMT-1700 (880 Newton max thrust) throttled way back.



I'd believe my guesses are accurate within a factor of two for
everything. If fact is worse than guess, 250 fpm climb for 8
minutes or 15 minutes of cruise at 50 knots is pretty
pitiful. On the other end, 1000 fpm or 120 knots for
an hour is pretty great.

The harder questions a
How to mount the thing?
Will it fit?
Where does the fuel tank go?
Weight and balance?
How about all that heat?
Who wants to fly it first?
Can it take off from under 2000 ft?
Who's got the cash?

Mark James Boyd wrote:

Eric Greenwell wrote:

Mark James Boyd wrote:
At 500 lbs, a notional Sparrowhawk with two AMT-450s

would accelerate at .12 g's (2 knots/second), to 40 knots
in 20 seconds using 1200 feet of runway. Assuming wheel
friction and drag make this figure double, under 2400
feet of runway is still respectable.

Wouldn't that be (500/(45+45) = 0.18 g's ? Or 3.4 knots/second to 40
knots in 10.4 seconds, and about 330 feet? So doubling is only 600 feet.


I avoided the math and safe-sided the heck out of it and
got a way too big figure. Thanks for the extra work


Using one engine, 0.09 g's gives 1.7 knots/sec, 21 seconds to 40 knots,
and 640 feet, doubled to 1280. With all due respect to Mike B, I might
be happy with one engine.
Eric Greenwell


For self-launch, perhaps, but for 100 knot level flight,
or 500 fpm climb, 200 Newtons (45 lbf) may be not enough.
I haven't done the disciplined math for this, nor
do I know the actual drag in Newtons of the Sparrowhawk.
I suppose this can be calculated rather than SWAGed based
on weight and the shape of the polar, eh? Any takers?

That's an easy one. Basically, the weight/(L:d) at the speed of
interest. Sticking with the 500 pounds weight, the drag at best L (36)
is 500lb/36=14 pounds, leaving 30 pounds thrust to climb. 500/30=17 L
climbing; climb rate is [59 knots at best L]/17=3.5 knots 350 fpm. Not
great, but interesting. For 500 fpm climb, a 56 lbf unit would do it.

For a 2000 foot climb:

- 2000'/350fpm = 6 minutes
- 6 min x 460 grams/min = 1200 grams, or almost a gallon liquid.

So, carrying 5 gallons would give you one launch, a 4000 foot climb out
of a big holes, and some travel towards home at 100 knots.

The L at 100 knots ~ 12, so 500/12=41.5 lbf for level flight, so that
goal is met with one engine.

OK, these are a bit optimistic, because I assumed the engine added no
drag. It does show one engine is close to being good, but a 55-60 lbf
engine would be "ideal".

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Eric Greenwell
Washington State
USA

On 13 Jan 2004 10:55:44 -0700, (Mark James Boyd)
wrote:

OK, what the heck. How about a superlight, turbine powered,
short wing, aerobatic, under $40K aircraft that'll
do 100 knots under full power, burn 5 gal/hr at 50 knots
in level flight, and climb at 500+ ft/min gulping
20 gallons/hr?

Prepare for SWAGs (Scientific Wild Ass Guesses)...

Here's what I gathered from

www.usamt.com

www.windcraft.fi/pik27/perf/performance.htm

www.windward-performance.com

www.accurate-automation.com

The AMT engines will provide
20 Newtons of thrust (about 4lbf) for one hour with 1 gallon of JetA.

The Sparrowhawk, with a turbine engine extended, has drag of
maybe 100 Newtons at about 50 knots (this is a guess from the
PIK 27 site and windward, and assuming 60lbs fuel on board,
and the extended engine doubling the drag).
Sustained level flight at this speed requires 5 gal/hr.

At 100 knots, the Sparrowhawk should drag 400 Newtons, which
is 20 gal/hr. Or, the Sparrowhawk can climb at 500 ft/min
with the same fuel consumption.

Assuming we have about a 10 gallon tank (gimme some slack here,
yeah, JET A is 6.84 blah, but whatever...) we can climb at
full power for 30 minutes at 50 knots, or cruise at 100 knots
for 30 minutes in level flight, or cruise at 50 knots for
two hours.

This allows (based on published Sparrowhawk gross weight)
a 170# pilot and 30# of engine+accessories + 10 gallons of fuel.

If one wishes to keep it an "ultralight", the tank can be 5
gallons instead (and a 30# heavier pilot) with halved range.

So we get a 170# pilot with a 100NM range or 12,000 ft of
climb, or a 200# pilot with a 50NM range or 6000 ft of climb.

This also assumes two AMT-450 engines (400 Newton max thrust)
or one AMT-1700 (880 Newton max thrust) throttled way back.



I'd believe my guesses are accurate within a factor of two for
everything. If fact is worse than guess, 250 fpm climb for 8
minutes or 15 minutes of cruise at 50 knots is pretty
pitiful. On the other end, 1000 fpm or 120 knots for
an hour is pretty great.

The harder questions a
How to mount the thing?
Will it fit?
Where does the fuel tank go?
Weight and balance?
How about all that heat?
Who wants to fly it first?
Can it take off from under 2000 ft?
Who's got the cash?


When you do the performance calculation correctly you are in for a
surprise.

Jet engines have more power available the faster you go.

Draw power available vs airspeed(straight line) and also power
required for level flight.(sink rate x weight) The difference (divided
by weight)

is rate of climb available.

For the 400Kg 15/18m glider and 2 x AMT450's the best rate of climb
speed is somewhere in the 80 to 110 knot IAS range!

More after Monday.

Mike Borgelt

Single engine is around 50 to 70KIAS.

My D-2T does not self launch. After an aero tow the D-2T handbook says 216
nm range based on sawtooth method at 882lbs gross weight, 3.43 gal of usable
fuel. I don't think that any current small jet engine approach can even
approach this. I think it will take a high bypass fan to compete with my
current and existing performance. Any one need a copy of the Flight Manual
pages documenting this performance?

Bob Kibby "2BK"

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"Mike Borgelt" wrote in message
...
On 13 Jan 2004 10:55:44 -0700, (Mark James Boyd)
wrote:

OK, what the heck. How about a superlight, turbine powered,
short wing, aerobatic, under $40K aircraft that'll
do 100 knots under full power, burn 5 gal/hr at 50 knots
in level flight, and climb at 500+ ft/min gulping
20 gallons/hr?

Prepare for SWAGs (Scientific Wild Ass Guesses)...

Here's what I gathered from

www.usamt.com

www.windcraft.fi/pik27/perf/performance.htm

www.windward-performance.com

www.accurate-automation.com

The AMT engines will provide
20 Newtons of thrust (about 4lbf) for one hour with 1 gallon of JetA.

The Sparrowhawk, with a turbine engine extended, has drag of
maybe 100 Newtons at about 50 knots (this is a guess from the
PIK 27 site and windward, and assuming 60lbs fuel on board,
and the extended engine doubling the drag).
Sustained level flight at this speed requires 5 gal/hr.

At 100 knots, the Sparrowhawk should drag 400 Newtons, which
is 20 gal/hr. Or, the Sparrowhawk can climb at 500 ft/min
with the same fuel consumption.

Assuming we have about a 10 gallon tank (gimme some slack here,
yeah, JET A is 6.84 blah, but whatever...) we can climb at
full power for 30 minutes at 50 knots, or cruise at 100 knots
for 30 minutes in level flight, or cruise at 50 knots for
two hours.

This allows (based on published Sparrowhawk gross weight)
a 170# pilot and 30# of engine+accessories + 10 gallons of fuel.

If one wishes to keep it an "ultralight", the tank can be 5
gallons instead (and a 30# heavier pilot) with halved range.

So we get a 170# pilot with a 100NM range or 12,000 ft of
climb, or a 200# pilot with a 50NM range or 6000 ft of climb.

This also assumes two AMT-450 engines (400 Newton max thrust)
or one AMT-1700 (880 Newton max thrust) throttled way back.



I'd believe my guesses are accurate within a factor of two for
everything. If fact is worse than guess, 250 fpm climb for 8
minutes or 15 minutes of cruise at 50 knots is pretty
pitiful. On the other end, 1000 fpm or 120 knots for
an hour is pretty great.

The harder questions a
How to mount the thing?
Will it fit?
Where does the fuel tank go?
Weight and balance?
How about all that heat?
Who wants to fly it first?
Can it take off from under 2000 ft?
Who's got the cash?


When you do the performance calculation correctly you are in for a
surprise.

Jet engines have more power available the faster you go.

Draw power available vs airspeed(straight line) and also power
required for level flight.(sink rate x weight) The difference (divided
by weight)

is rate of climb available.

For the 400Kg 15/18m glider and 2 x AMT450's the best rate of climb
speed is somewhere in the 80 to 110 knot IAS range!

More after Monday.

Mike Borgelt

Single engine is around 50 to 70KIAS.