|Nov 17, 2014, 03:21 AM|
United States, TX, Lipan
Joined Jul 2013
Troy Built Models UAV's
Looking for RTH (return to home) and gyro units Troy Built Models popped up in my search results. It was hard not to notice the UAV's in stock especially since several were big $$$$. What really caught my attention is the engine size, in fact I double checked it.
UAV Penguin B
MTOW 47.4 lbs 21.5 kg
Empty Weight (excl. fuel and payload) 22.05 lbs 10 kg
Wing Span 10.83 ft 3.3 m
Length 7.45 ft 2.27 m
Powerplant 2.5 hp
Max Payload 22.05 lbs 10 kg
My calculator says the power to weight ratio is 19:1 which seems on the low side of low. Of course the UAV is blasted into the air with a compressed air launcher i.e. like a V1 buzz bomb . No ROG rise of ground take-offs are shown either. Since many of you have practical experience in this area, it appears with this pwr/weight a paved runway and rather long TO roll would be needed to get airborne?
Am I missing something here? I have always considered 10:1 normal and 15:1 a stretch for aircraft small or large to operate in. In fact I doubt at 19:1 this UAV could take-off on an unimproved grass field. Additionally, given a wind of >10 mph could this UAV make any headway rather just hover especially considering the frontal area.
I would appreciate your thoughts especially since other UAV's aren't as aerodynamic still use this same engine.
|Nov 17, 2014, 11:25 AM|
Joined Feb 2007
The Penguin B exists in relatively large numbers, so I guess it must be doing something right. We have one at my job, but I don't get to fly it. A grass take off would be challenging, but in the air it's ok.
|Nov 17, 2014, 04:22 PM|
Palo Alto, California, United States
Joined Jan 2003
My company sells a similar aircraft (MLB Super Bat) and we regularly fly at 47lb GTOW, but we use a modified DA-50 for power. We dyno tested this engine at 4.0 HP. I don't think 2.5 HP at 47 lb is good enough for the work we do, but many people operate their planes heavily loaded without much climb margin.
|Nov 20, 2014, 03:31 PM|
There was a good write-up on the Penguin B in the first issue of Unmanned Systems Technology magazine. Apparently, they have only made 100 -- which is a smaller number than I assumed.
I think it is optimized in the 35-40 knot range so a 10mph wind wouldn't be an issue. Keep in mind smaller electric systems such as the AV Puma are rated in winds up to 25kts.
If the lift to drag ratio of PB is ~20:1 like Aerosonde, then they don't need much power at all to maintain altitude. Yes, takeoff roll and climb rate will suffer from basic physics, but most missions wouldn't require this .. and you could always takeoff light if you wanted more climb, or better altitude performance.
Endurance is always a want for these birds so that's what drives the low power to weight ratios.
|Nov 22, 2014, 01:26 PM|
United States, IL, Edwardsville
Joined Dec 2011
Is the math adding up on that tbm spec on the penguin b? The fuel burn is off? Am I missing sonething? Fabulous looking airframe!
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