If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below. 


Thread Tools  Display Modes 
#1




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.windwardperformance.com www.accurateautomation.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 AMT450 engines (400 Newton max thrust) or one AMT1700 (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? 
Ads 
#2




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 prepreg 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 
#3




Scale up a BD5J 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.windwardperformance.com www.accurateautomation.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 AMT450 engines (400 Newton max thrust) or one AMT1700 (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? 
#4




In article ,
Mark Zivley wrote: Scale up a BD5J 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 AMT450s 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 (BD5), 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 flyoff 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). 
#5




Mark James Boyd wrote:
At 500 lbs, a notional Sparrowhawk with two AMT450s 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.   change "netto" to "net" to email me directly Eric Greenwell Washington State USA 
#6




Eric Greenwell wrote:
Mark James Boyd wrote: At 500 lbs, a notional Sparrowhawk with two AMT450s 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 safesided 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 selflaunch, 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? 
#7




been done.. either APIS or Silent.. check out their web page..
BT "Mark James Boyd" wrote in message news:[email protected] 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.windwardperformance.com www.accurateautomation.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 AMT450 engines (400 Newton max thrust) or one AMT1700 (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? 
#8




Mark James Boyd wrote:
Eric Greenwell wrote: Mark James Boyd wrote: At 500 lbs, a notional Sparrowhawk with two AMT450s 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 safesided 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 selflaunch, 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 5560 lbf engine would be "ideal".   change "netto" to "net" to email me directly Eric Greenwell Washington State USA 
#9




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.windwardperformance.com www.accurateautomation.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 AMT450 engines (400 Newton max thrust) or one AMT1700 (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. 
#10




My D2T does not self launch. After an aero tow the D2T 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 mailbox protected from junk email by Matador from MailFrontier, Inc. http://info.mailfrontier.com "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.windwardperformance.com www.accurateautomation.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 AMT450 engines (400 Newton max thrust) or one AMT1700 (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. 
Thread Tools  
Display Modes  


Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
Sport Pilot  School Won't Offer  Gary G  Piloting  38  February 16th 05 11:41 AM 
"I Want To FLY!"(Youth) My store to raise funds for flying lessons  Curtl33  General Aviation  7  January 10th 04 12:35 AM 
I wish I'd never got into this...  Kevin Neave  Soaring  32  September 19th 03 12:18 PM 
Restricting Glider Ops at Public Arpt.  rjciii  Soaring  36  August 25th 03 04:50 PM 
Announce/USA: FAA Glider Flying Handbook / Bob Wander  SoarBooks  Soaring  0  August 11th 03 03:55 PM 