Jet Glider Sparrowhawk

[Mark James Boyd]

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 are:
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?

[Eric Greenwell]

Mark James Boyd wonders about "turbinizing" the SparrowHawk:

> The harder questions are:
> 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...
--
-----
change "netto" to "net" to email me directly

Eric Greenwell
Washington State
USA

[Mark Zivley]

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 are:
> 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]

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).

[Eric Greenwell]

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

[Mark James Boyd]

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? :)

[BTIZ]

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 are:
> 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?

[Eric Greenwell]

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:D (36)
is 500lb/36=14 pounds, leaving 30 pounds thrust to climb. 500/30=17 L:D
climbing; climb rate is [59 knots at best L:D]/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:D 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

[Mike Borgelt]

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 are:
>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.

[Bob Kibby]

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 are:
> >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.
>
>

[Bill Daniels]

"Eric Greenwell" > wrote in message
...
> 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:D (36)
> is 500lb/36=14 pounds, leaving 30 pounds thrust to climb. 500/30=17 L:D
> climbing; climb rate is [59 knots at best L:D]/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:D 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".
>
> --
> -----
> change "netto" to "net" to email me directly
>
> Eric Greenwell
> Washington State
> USA

Have you math whizzes figured out how far the wing runner will have to run
before this dog whistle is going fast enough to have aileron control?

Bill Daniels

[Eric Greenwell]

Bill Daniels wrote:


>>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".

> Have you math whizzes figured out how far the wing runner will have to run
> before this dog whistle is going fast enough to have aileron control?

Wing runner? On an 11 meter motorglider? We don't need no stinking wing
runners! This is _Self_ launching! Put wing tip wheels on it and let it
roll! Actually, letting it slide on it's plastic pads would work fine,
since there is so little weight on the tip. The wing will come up when
it's ready. In crosswinds, put the downwind wing down, to help keep it
straight. The ultimate answer is a tailwheel with just enough steering
ability to keep it straight, since it doesn't need to taxi.

--
-----
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Eric Greenwell
Washington State
USA

[TomnKeyLargo]

Current Jet Cat turbines require propane to start them. The RC Jet guys at our
field have a whole bunch of Jet RC planes and fly from our field several days a
week. Including a FAA safety Inspector. The Jet Cat turbines due to using
propane for start, cannot be started inflight. The wind with blow out the
flame. Also, our RC guys do have flameouts everyso often requiring them to have
a dead stick landing. Jet-RPM of Sweden is making a Jet turbine, I have spoken
with him. His Jet Turbines will have a electric start, he hopefully will be
ready soon to start selling them. He said the price would be around 3450 euros,
this was several months ago. To prep a current Jet Cat for engine start does
take alittle time. I believe in March, in Lakeland, Florida the Jet RC people
are going to have a big meet. You might want to check it out. Jet RPM said
several sailplane manufactures have spoken to him already. It appears the small
turbine with a electric start could become a substainer with inflight start
very soon. Tom

[Eric Greenwell]

Bob Kibby wrote:

> 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.

Two stroke engines are much more economical, for sure, but the turbine
_seems_ to promise a simpler, more reliable, more easily started system
and much less drag while the engine is out, especially interesting in an
engine failure situation. And there is the ability to cruise
significantly faster.

> Any one need a copy of the Flight Manual
> pages documenting this performance?

Nah, my ASH 26 E manual says I can go 290 nm on that much fuel, so I
believe you (I'm not sure I believe the manual, though!)

--
-----
change "netto" to "net" to email me directly

Eric Greenwell
Washington State
USA

[Mark James Boyd]

Bill Daniels > wrote:
>
>Have you math whizzes figured out how far the wing runner will have to run
>before this dog whistle is going fast enough to have aileron control?

Well, we've got a name for the project!

Project Dog Whistle. LOL

And Bill rightly points out that if the thrust
is behind the CG, any yaw at low speeds means
a ground loop on takeoff unless the tailwheel is
firmly tracking.

One more reason why the twin Cri-cri version had it
right, with the two engines well ahead of the
CG, and with exhaust away from anything that might burn.

[Mark James Boyd]

Mike Borgelt > wrote:
>
>When you do the performance calculation correctly you are in for a
>surprise.
>
>Jet engines have more power available the faster you go.

The downside of this is if the specs are for thrust in Newtons
available at a certain airspeed (not 0). At 0 airspeed, it
may be that the AMT-400 puts out significantly less power.
This would extend the takeoff roll some, and decrease efficiency
at any airspeed lower than "spec."

Or maybe the spec is for thrust on a test stand, who knows?

[Steve Davis]

A Genesis owner in Sweden is planning to install one
or two jet engines which will pop out of the BRS hatch.
He's planning to use the electric start version which
is being developed. His progress can be monitored
on www.genesisflyers.com He has also done some wing
root fillet modifications and testing to improve low
speed air flow. Good pictures and descriptions.


At 05:06 14 January 2004, Tomnkeylargo wrote:
>Current Jet Cat turbines require propane to start them.
>The RC Jet guys at our
>field have a whole bunch of Jet RC planes and fly from
>our field several days a
>week. Including a FAA safety Inspector. The Jet Cat
>turbines due to using
>propane for start, cannot be started inflight. The
>wind with blow out the
>flame. Also, our RC guys do have flameouts everyso
>often requiring them to have
>a dead stick landing. Jet-RPM of Sweden is making a
>Jet turbine, I have spoken
>with him. His Jet Turbines will have a electric start,
>he hopefully will be
>ready soon to start selling them. He said the price
>would be around 3450 euros,
>this was several months ago. To prep a current Jet
>Cat for engine start does
>take alittle time. I believe in March, in Lakeland,
>Florida the Jet RC people
>are going to have a big meet. You might want to check
>it out. Jet RPM said
>several sailplane manufactures have spoken to him already.
>It appears the small
>turbine with a electric start could become a substainer
>with inflight start
>very soon. Tom
>

[Mark James Boyd]

Bob Kibby > wrote:
>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"

This turbine approach absolutely will not compare to the fuel
efficiency of a piston engine. Our point was simply that
fuel efficiency issues are dwarfed by the other advantages of
a turbine. Four times a small number is a small number.
If the turbine uses four times as much fuel (14 gallons in this
case) we are really talking about an additional 70 pounds/$20
of fuel, which we believe is a minor additional cost
compared to the other advantages a turbine provides.

This is clearly not true for ALL applications (if the 70# extra
means you are over gross and can't fly, then this kills the
whole idea). But on balance, for many cases, it looks like the
turbine idea, with it's fuel inefficiency, is interesting...

[Alan Baker]

In article <4004fb99$1@darkstar>,
(Mark James Boyd) wrote:

> Bill Daniels > wrote:
> >
> >Have you math whizzes figured out how far the wing runner will have to run
> >before this dog whistle is going fast enough to have aileron control?
>
> Well, we've got a name for the project!
>
> Project Dog Whistle. LOL
>
> And Bill rightly points out that if the thrust
> is behind the CG, any yaw at low speeds means
> a ground loop on takeoff unless the tailwheel is
> firmly tracking.

No it doesn't. The thrust is always directed through the centre of mass.

It's position of the main wheel with respect to the CM that matters for
a ground loop...

>
> One more reason why the twin Cri-cri version had it
> right, with the two engines well ahead of the
> CG, and with exhaust away from anything that might burn.
>

--
Alan Baker
Vancouver, British Columbia
"If you raise the ceiling 4 feet, move the fireplace from that wall
to that wall, you'll still only get the full stereophonic effect
if you sit in the bottom of that cupboard."

[Vaughn]

"Mark James Boyd" > wrote in message
news:4004fb99$1@darkstar...
> Bill Daniels > wrote:
> >
> One more reason why the twin Cri-cri version had it
> right, with the two engines well ahead of the
> CG, and with exhaust away from anything that might burn.

But introduces the possibility (certainty?) of asymmetric thrust! I
saw a Cri-cri (piston) lose power on TO one year at Oshkosh, it crashed
almost at the crowd line.

Vaughn


>

[Mark James Boyd]

Alan Baker > wrote:

>> Project Dog Whistle. LOL
>>
>> And Bill rightly points out that if the thrust
>> is behind the CG, any yaw at low speeds means
>> a ground loop on takeoff unless the tailwheel is
>> firmly tracking.
>
>No it doesn't. The thrust is always directed through the centre of mass.
>
>It's position of the main wheel with respect to the CM that matters for
>a ground loop...
>
>Alan Baker

Correct. I'm mixing apples and oranges. In our Sparrowhawk design,
the engine(s) thrust is through the center of mass, so this
doesn't matter.

I wonder about the Genesis mock-up, where this may not be the case.

[Mark James Boyd]

Vaughn > wrote:
>
>> One more reason why the twin Cri-cri version had it
>> right, with the two engines well ahead of the
>> CG, and with exhaust away from anything that might burn.
>
> But introduces the possibility (certainty?) of asymmetric thrust! I
>saw a Cri-cri (piston) lose power on TO one year at Oshkosh, it crashed
>almost at the crowd line.
>
>Vaughn

Probably because the Cri-cri is such a terrible glider...
A lot in common with the BD-5: rotation speed = Vne = Va =
Vmc = Vs... (or nearly so). ;( The Gruman Yankee also had
critical speeds close together, and the Speed Canard had a
real high stall speed too. One of the reasons I LOVE gliders
is the generally low stall speed.

Some full size regional jets, and the RC models that use the
little turbines, have placed the twin turbines very close
together and near the rear with no blast towards surfaces.
It would be great to put turbine(s) on the tail of the Sparrowhawk,
but the CG would never, ever work...

Alas, back to the drawing board...

[Vaughn]

"Mark James Boyd" > wrote in message
news:40057f22$1@darkstar...
> Vaughn > wrote:
> >
> >> One more reason why the twin Cri-cri version had it
> >> right, with the two engines well ahead of the
> >> CG, and with exhaust away from anything that might burn.
> >
> > But introduces the possibility (certainty?) of asymmetric thrust! I
> >saw a Cri-cri (piston) lose power on TO one year at Oshkosh, it crashed
> >almost at the crowd line.
> >
> >Vaughn
>
> Probably because the Cri-cri is such a terrible glider...

Probably so, but I see I was not clear in my above post. The Cri-cri
apparently lost power in one engine only, the one towards the crowd. We
were sitting at the crowd line, but at the other end of the field, so we
were not among the menaced. Looking at the Cri-cri, the engines look close
enough together that you would think that asymmetric thrust would not be a
problem; apparently not so.

Vaughn

[Alan Baker]

In article <40057c28$1@darkstar>,
(Mark James Boyd) wrote:

> Alan Baker > wrote:
>
> >> Project Dog Whistle. LOL
> >>
> >> And Bill rightly points out that if the thrust
> >> is behind the CG, any yaw at low speeds means
> >> a ground loop on takeoff unless the tailwheel is
> >> firmly tracking.
> >
> >No it doesn't. The thrust is always directed through the centre of mass.
> >
> >It's position of the main wheel with respect to the CM that matters for
> >a ground loop...
> >
> >Alan Baker
>
> Correct. I'm mixing apples and oranges. In our Sparrowhawk design,
> the engine(s) thrust is through the center of mass, so this
> doesn't matter.
>
> I wonder about the Genesis mock-up, where this may not be the case.

How can it really be otherwise?

And what's more, a ground loop is cause when the main wheel -- ahead of
the CM -- develops a sideways force which causes further yaw, which
causes larger sideways force, etc.

Even mounted off the CM laterally, and engine would still be fixed to
the fuselage and hence the yaw force would be *constant*.

--
Alan Baker
Vancouver, British Columbia
"If you raise the ceiling 4 feet, move the fireplace from that wall
to that wall, you'll still only get the full stereophonic effect
if you sit in the bottom of that cupboard."

[Ruud Holswilder]

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


>
>www.usamt.com
>
In the specifications I also see a AT1500 engine that delivers 670 N @
75,000 rpm.
Should be more than enough thrust to modify my DDT into a DDJ ?

[Bill Daniels]

"Ruud Holswilder" > wrote in message
...
> On 13 Jan 2004 10:55:44 -0700, (Mark James Boyd)
> wrote:
>
>
> >
> >www.usamt.com
> >
> In the specifications I also see a AT1500 engine that delivers 670 N @
> 75,000 rpm.
> Should be more than enough thrust to modify my DDT into a DDJ ?

If not, you can add the afterburner! (re-heat)

Bill Daniels

[Steve Davis]

Early models of the KC-135 tanker used water injection
on takeoff for added thrust. No idea how much additional
thrust could be gained by adding this to a 45Lb thrust
turbine but it wouldn't increase fuel consumption the
way an afterburner would. How about a cowling around
the jet and water could be sprayed or misted onto the
exhaust section. Could the steam then mix with the
exhaust well enough to increase thrust or would it
be a perpetual motion add on?

>If not, you can add the afterburner! (re-heat)
>
>Bill Daniels

[Bert Willing]

The water was injected into the combustion chamber, not the exhaust.
Evaporation increased the pressure in the chamber without increasing
temperature too much. In the 70's, there has been a spectacular accident of
a Lockheed Tristar outbound Hamburg where the mechanics put fuel ino the
according tanks instead of water - resulting in all three engines failing
during the initial climb, and the aircraft passing underneath a bridge of a
local highway. Partially passing, that is :-(

--
Bert Willing

ASW20 "TW"


"Steve Davis" > a écrit dans le message
de ...
> Early models of the KC-135 tanker used water injection
> on takeoff for added thrust. No idea how much additional
> thrust could be gained by adding this to a 45Lb thrust
> turbine but it wouldn't increase fuel consumption the
> way an afterburner would. How about a cowling around
> the jet and water could be sprayed or misted onto the
> exhaust section. Could the steam then mix with the
> exhaust well enough to increase thrust or would it
> be a perpetual motion add on?
>
> >If not, you can add the afterburner! (re-heat)
> >
> >Bill Daniels
>
>
>

[F.L. Whiteley]

I had no appreciation for how much water was injected until I saw the fire
go out in a KC-135 engine one day when they hit the water after throttle up.
Quite a splash.

Frank Whiteley

"Bert Willing" > wrote in
message ...
> The water was injected into the combustion chamber, not the exhaust.
> Evaporation increased the pressure in the chamber without increasing
> temperature too much. In the 70's, there has been a spectacular accident
of
> a Lockheed Tristar outbound Hamburg where the mechanics put fuel ino the
> according tanks instead of water - resulting in all three engines failing
> during the initial climb, and the aircraft passing underneath a bridge of
a
> local highway. Partially passing, that is :-(
>
> --
> Bert Willing
>
> ASW20 "TW"
>
>
> "Steve Davis" > a écrit dans le
message
> de ...
> > Early models of the KC-135 tanker used water injection
> > on takeoff for added thrust. No idea how much additional
> > thrust could be gained by adding this to a 45Lb thrust
> > turbine but it wouldn't increase fuel consumption the
> > way an afterburner would. How about a cowling around
> > the jet and water could be sprayed or misted onto the
> > exhaust section. Could the steam then mix with the
> > exhaust well enough to increase thrust or would it
> > be a perpetual motion add on?
> >
> > >If not, you can add the afterburner! (re-heat)
> > >
> > >Bill Daniels
> >
> >
> >
>
>

[Bill Daniels]

Water injection works but glowing shock diamonds in an afterburners exhaust
would be cool. Noisy, but cool.

Bill Daniels

"Steve Davis" > wrote in message
...
> Early models of the KC-135 tanker used water injection
> on takeoff for added thrust. No idea how much additional
> thrust could be gained by adding this to a 45Lb thrust
> turbine but it wouldn't increase fuel consumption the
> way an afterburner would. How about a cowling around
> the jet and water could be sprayed or misted onto the
> exhaust section. Could the steam then mix with the
> exhaust well enough to increase thrust or would it
> be a perpetual motion add on?
>
> >If not, you can add the afterburner! (re-heat)
> >
> >Bill Daniels
>
>
>

[Mark James Boyd]

Well, I've looked into canards, and as a previous
poster pointed out, modern canards sacrafice a bit of
efficiency over trailing tailbooms.

So if this is out, canting engines to the side, or down, seems
a good choice. Doing this with a single engine is awkward.
So perhaps the engine right out the tail?

Hmmm....

[c1rrus]

Mark James Boyd wrote:

> Well, I've looked into canards, and as a previous
> poster pointed out, modern canards sacrafice a bit of
> efficiency over trailing tailbooms.
>
> So if this is out, canting engines to the side, or down, seems
> a good choice. Doing this with a single engine is awkward.
> So perhaps the engine right out the tail?
>
> Hmmm....
Look at Max Barel's "Graal" experimental glider in France.
http://perso.wanadoo.fr/max.barel/Graal/overview.html
Seems to work rather well.