Possible project: The Martin Jetpack

[Andrew Wendling]

Anyone want try to tackle making one of these in the next year or two?

https://www.youtube.com/watch?v=mdQK_odgedk

Some magnesium castings could help it out.

[Andrew Wendling]

http://www.martinjetpack.com/

[Rick B]

Building one would be fun. Flying one that we built? Nope.

http://www.martinjetpack.com/

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[Joseph Mckibben]

Lol. Yeah maybe we should make it unmanned at first. And stand really far way.

[Brent Kerlin]

...and have multiple videos running for the Youtubes.

Thanks,
Brent S. Kerlin

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[Eoin Ross]

Ahh ya pansy!!

Mind you ... thats not a bad thing some times right?

There's old pilots, there's bold pilots... there's no bold, old pilots.

https://www.youtube.com/watch?v=OPTMlVLDrX8

[Joseph Mckibben]

Yeah I was thinking small scale first would be the way to go.

[Andrew Wendling]

I think what intrigues me the most about this are the pros and cons between electric and internal combustion. Why was gas chosen?

My guesses -

Electric Pros:

Amazing torque

Electric Cons:

heavy battery 

Static weight as fuel is used

Gas Engine Pros:

Less overall weight vs a battery

Lightens in weight during operation

Gas Engine Cons:

Tougher to control via an arduino?

Heat generated

......and much more I don't know.

On Monday, March 23, 2015 at 11:18:10 AM UTC-4, Andrew Wendling wrote:

[Andrew Wendling]

For the number crunchers:

Electric Motorcycle Specs:

https://www.mission-motorcycles.com/rs

The V4 Engine designed by Martin Jetpack

http://www.martinjetpack.com/technical/v4-engine

On Monday, March 23, 2015 at 11:18:10 AM UTC-4, Andrew Wendling wrote:

[Rick Burner]

That's a kick a$$ motorcycle. I would rather build the motorcycle. I could actually ride it without needing a new pair of pants.

Rick

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[Ken Bailey]

Probably because there is an insane amount of energy potential in liquid fuel. Even with the most advanced lipo technology, gas contains a multitude higher energy and power density. And if your goal is lift, weight is an important factor. That's my guess.

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[Eoin Ross]

I was in total agreement with you Ken until I looked at these numbers...
 Source                                  Specific energy (MJ/kg)     Energy density (MJ/L)
LiPo batteries                               100–265                           250–730
LPG (including Propane / Butane)       46.4                                 26    
Jet fuel (Kerosene)                             46                                    37.4
Gasoline (petrol)                                 44.4                                 32.4

http://www.barnardmicrosystems.com/UAV/engines/batteries.html

Throw into this internal combustion engines are only ~25% thermally efficient vs electric motors being better than 80% and this looks even worse.

A main reason electric motors vs nitro motors are used in multirotors are ease of control and 'instant' response. There is a new multirotor design out there that looks like it could run on an ICE... http://diydrones.com/profiles/blogs/stingray-500-a-collective-pitch-multirotor

My suspicions are now on the ability to refuel in minutes vs recharging, and availability of fuel are the main reasons.

Eoin.

[Eoin Ross]

One thing I didn't look at here is power to weight ratio for the drive train!

I can almost lift a 55HP 1300cc ICE, Two can do it pretty easily.

50/55HP electric motors are around 300 lb
https://www.inverterdrive.com/group/Motors-DC/40kW-DC-Motor-TT-Electric-2250RPM-54HP-shunt/default.aspx

[robbytow...@gmail.com]

I think the unit conversion from Wh/kg to MJ/kg may be off - http://www.unitconversion.org/energy/megajoules-to-watt-hours-conversion.html., http://en.wikipedia.org/wiki/Energy_density

[Joseph Mckibben]

This a 72 Hp motor only 115lbs. http://www.evwest.com/catalog/product_info.php?products_id=83

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[Eoin Ross]

One column is per kilogram, and the other per litre
I might have the LiPo line swapped too - the figures came from two different sources

A table on here has them all now I take another look...
https://en.wikipedia.org/wiki/Energy_density

Storage material

Specific energy (MJ/kg)	Energy density (MJ/L)

methane or natural gas	55.5	0.0364
Diesel / Fuel oil	48	35.8

LPG (including Propane / Butane)	46.4	26
Jet fuel (Kerosene)	46	37.4
Gasoline (petrol)	44.4	32.4

Ethanol fuel (E100)	26.4	20.9
Methanol fuel (M100)	19.7	15.6
Lithium battery (non-rechargeable)	1.8	4.32
Lithium-ion battery	0.36[4]–0.875	0.9–2.63

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[Ken Bailey]

I was wondering. I didn't think they had advanced battery technology that quickly.

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[Eoin Ross]

Rookie mistake ... anytime you get something that totally contradicts what you think you've heard - take another look! [Smack forehead]

Eoin

[Andrew Wendling]

- Says the Honeywell Aerospace Engineer

Oh yeah, FYI, I've been talking about DD to my engineering contacts. Some of them want to meet the group.

Andrew J. Wendling

Manufacturing Engineer

Spektracast Engineering and Prototyping LLC

660 Milburn Ave. 

Dayton, Ohio 45404
Phone: (937) 239-0177

[Joseph Mckibben]

A lot of this depends on how long you really want this to fly though.

[Joseph Mckibben]

About 60 of these would probably generate enough thrust lol.
 
http://www.ebay.com/itm/Electric-EDF-120mm-Ducted-Fan-Set-12-Blades-With-5052-motor-kv500-Tested-Balance/271558843999?_trksid=p2054897.c100204.m3164&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D20140407115239%26meid%3Dbc650cd8bdd6468ca98a8175108414b8%26pid%3D100204%26rk%3D1%26rkt%3D30%26sd%3D121548665519