Bob Barrows and his Electric Ultralight Flying Machine

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Armilite

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.
needs a B&S v twin.....
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If you notice in this Video it must have been made before the FFA made the final Ruling that Battery Weight is Included in the total Empty Weight. Listen at 5:20 where he is talking about it probably coming in at 250 lbs without the batteries!

As Airframe sat, not done yet, he was at 120 lbs, Wings 25 lbs each equals 170 lbs and not done yet. Batteries for 45min of Flight he said was 75 Lbs and you still have Motor & Controller Weight. You still need a Reserve, so more like 35 min, with a 10min Reserve!

The Lazair MTOW 450 lbs with (2) Rotax 185's had an Empty weight: 210 lbs (95 kg). The 185UL 9.4hp each were around 28 lbs x 2 = 56 lbs. 210 lbs - 56 lbs = 154 lbs for Airframe. That left 100 lbs for Batteries, Controller & Motor & Brackets. When the Designer of the Lazair tried to convert it to Electric, 45min was all he could get with (2) 11hp Motors.

Lazair MTOW 450 lbs - 254 lbs = 196 lbs for Pilot & Bags.

A pair of 185UL's gave you 2hrs of Flight with a Reserve on 5 Gallons of Gas.
 

TLAR

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I have planted the Vtwin seed, hopefully it will take root!
I would like to see a Bob Barrows Vtwin!!!
 
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Armilite

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I have planted the Vtwin seed, hopefully it will take root!
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These Honda/Clone GX390+ Singles are lighter and go up to about 676cc today! A 420 can make 37hp with the Upgrades. A Harbor Freight 420 is $399.99 cheaper when on Sale. A Duromax 440 Electric Start on eBay & Amazon is the Best Bang for your dollar.
 

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TLAR

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I am having trouble deciding on what to build, Bob’s ultralight or the Sky Dog (a Sky Pup with a MTOW of #500), either one will have a 4stroke industrial engine
 

AJLiberatore

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Batteries, Carbon Fiber, bonding aluminum, Mmmmm
In a world gone mad, how can you not gravitate to Bob's common sense & simplicity utilized in his designs. He's so underrated as a designer imho, think Colin Chapman & Steve Wittman. If the EV experiment doesn't work, I wonder if the ZDZ 500 w/ the reduction drive would fit the bill. Chk out BD5 Pilot on YouTube as he is moving toward utilizing that engine.
 

TLAR

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Oh believe me, I love the Bearhawk Ultralight, it’s just that I have a lot of time invested in the Sky Dog
Edit—maybe I should just build both
 

TLAR

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In a world gone mad, how can you not gravitate to Bob's common sense & simplicity utilized in his designs. He's so underrated as a designer imho, think Colin Chapman & Steve Wittman. If the EV experiment doesn't work, I wonder if the ZDZ 500 w/ the reduction drive would fit the bill. Chk out BD5 Pilot on YouTube as he is moving toward utilizing that engine.
Call Bob and make make that suggestion
 

TLAR

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In a world gone mad, how can you not gravitate to Bob's common sense & simplicity utilized in his designs. He's so underrated as a designer imho, think Colin Chapman & Steve Wittman. If the EV experiment doesn't work, I wonder if the ZDZ 500 w/ the reduction drive would fit the bill. Chk out BD5 Pilot on YouTube as he is moving toward utilizing that engine.
I found the video and will check out the ZDZ option, thanks
 

wanttobuild

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Is a Yamaha scooter engine gonna end up being the preferred engine for this beauty?

Light weight, four stroke, water-cooled, fuel injected, belt reduction, uses a lightweight exhaust that can be scratch built.

You could use it to tow battery powered aloft for a lofty fee.
 

Armilite

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I am having trouble deciding on what to build, Bob’s ultralight or the Sky Dog (a Sky Pup with a MTOW of #500), either one will have a 4stroke industrial engine
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MTOW of 500 lbs = 226.7962 kg / 10 kg = 22.67962 kw needed = 30.41387 hp needed! A Honda/Clone 460 Single upgraded can make [email protected] With an ACE Belt Drive 5000rpm/1.8 Ratio = 2,777.777777777778 Prop rpm! Duromax has a New 500cc [email protected] Engine for their Generators. If you build a 440, 420, to the same Spec's as the 460 figure about +2hp/-2hp per +20cc/-20cc. Like a 460 (37hp), 440 (35hp), 420 (33hp). Go the other way a 480 (39hp), a 500 (41hp), etc. Singles go up to (100mm x 86.5mm) 679.6cc today. You can buy off-the-shelf 420's and 440's. Duromax isn't offering the 500 yet as a stand-alone engine. You can buy Clone kits to make about any CC you want up to 679.6cc. READ the Dyno Sheet it tells you the Spec's of the engine.
 

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Armilite

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My bet is that 29.98327 HP would be adequate.


BJC
===============

What Power to Weight Ratio any plane will fly well on, and what it will Fly minimum on is two different things. 85% of the USA Part 103's out there in the World flew with a Rotax 277UL with either [email protected] or a [email protected] Engine, but did they all Fly Well on that hp, I doubt it! If 450lbs MTOW needs 27.4 hp and 660 lbs need 40.1hp. Just as the Lazair flew marginally on (2) 5.5hp Chainsaw Engines = 11hp, but was soon upgraded to (2) Rotax 185UL's rated at 9.4hp each or 18.8hp, but many still weren't happy yet with its Performance, so some were upgraded to (2) Solo 210's at 15hp each = 30hp! The Lazairs MTOW of 450 lbs = 204.1166 kg / 10 kg = 20.41166 kw needed = 27.37249 hp needed or 27.37249 / 2 = 13.686245 hp each engine needs to make, if you want it to fly well. Today you have more engines to pick from and even some kit engines to meet your needs for hp.
 

n3puppy

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===============
What Power to Weight Ratio any plane will fly well on, and what it will Fly minimum on is two different things. .
What are the expected flight parameters for any aircraft to be considered "flying well"?

With 10 Kg/Kw?
Rate of Climb - ??? fpm
Take Off Roll - ??? feet
Distance to clear 50 ft - ??? feet

What are the same expected numbers at
11 Kg/Kw ?? - (Poor flying)
9 Kg/Kw ??- (Better flying)
 

rick9mjn

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ni ,ill ,usa
my understanding of the problems of what 'Brian Carpenter" of Rainbow Aviation ,
of his company trying to build a Electric Ultralight / glider ,
and the F.A.A being locked in on the max weight of 256 pounds for whole weight for the ultralight ,
and the F.A.A also would ""not"" allow for the adding of the weight the gasoline ......
and because gasoline weights 6.3 pounds per gallon , and a ultralight can carry 5 gallons.
so the (expletive deleted) F.A.A says ;
a gasoline powered ultralight can weight 31.5 pounds more than a electric ultralight.
....../rick
 
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