Another Bensen rebuild

dabkb2

Dave Bacon
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I found this at Brown Field a couple weeks ago and had to bring it home
 

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dabkb2

Dave Bacon
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I am thinking of going electric with it. The motors, controls and batteries have come a long way, I am going to give it another look and see if it is possible. With a single place Bensen all I need is 60 HP, and that is doable, I just need to look into batteries some more and see what this might cost, and how long of flights I can get.
 

Doug Riley

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Dave, with a big-slow rotor, you can get away with even less than 60 hp. The 40 hp Air Command 447 wasn't TOO bad, and the 447 Gyrobee is noticeably better.
 

Brian Jackson

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Doug Riley;n1137419 said:
Dave, with a big-slow rotor, you can get away with even less than 60 hp. The 40 hp Air Command 447 wasn't TOO bad, and the 447 Gyrobee is noticeably better.

Hi Doug. Not to get too off topic, but being unfamiliar with the Air Command, what design characteristics made the 'Bee better than the AC with the same 40 HP? Thanks.
 

Kevin_Richey

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Bee has much better thrustline location compared to a high one in the original Air Commands. Those originally-designed ACs also did not come equipped w/ a horizontal stabilizer, while the Bee has one.

Doug has repeatedly told us over the years how "KNIFE-EDGE" it felt to fly his original AC. Extreme nose down as higher speeds flown. Stick movements became extremely sensitive @ those higher speeds. Constantly chopping throttle when encountering turbulence, trying to avoid the PPO that claimed many lives in like-equipped Bensens and Air Commands.
 

dabkb2

Dave Bacon
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I agree it does not need 60hp to fly, but if it is available why not try for it. At 40hp in El Mirage, 3000' plus air density, more is always better.

I hope to find something out this week, 60hp with a 68" prop might not be the same thing as with a 52" prop.

It would be nice to come up with a direct replacement for the Mac, there are a lot of Bensen's out there, but I am afraid it will lose something in the translation, going from the loudest gyro to a almost silent one, might take some getting use to.
 

dabkb2

Dave Bacon
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I agree, the higher speeds get a little spooky, I have had my Mac to almost 100kts and it is very sensitive. But there is no need to ever go there, with an open frame gyro it is much more comfortable at 50.
 

PW_Plack

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dabkb2;n1137443 said:
...I am afraid it will lose something in the translation, going from the loudest gyro to a almost silent one, might take some getting use to.

Gee Dave, I thought Mac pilots made that transition almost every flight! :smile:
 

dabkb2

Dave Bacon
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I got some info tonight, it will take 3 40lbs batteries to last an hour at 60hp. the motor and controller are 47lbs. GREAT that will work!!! That is just a little more than a 582 with fuel for an hour.
The motor and controller are $2500.00, so far so good. Now the bad part the batteries are $3000.00 each. I knew the batteries would be expensive but I was thinking $1000.00 each for a total cost of $5500.00. I am not willing to spend twice that, but hey it looks like they have the motors and batteries that will do the job. When I looked into this 5 years ago there were no motors or batteries that would do the job. Maybe in 5 more years the price will be affordable.
 

neutrax

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I like it. Go rob a small bank.
 

dabkb2

Dave Bacon
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If you want to make a small fortune in aviation, start with a large one.
 

PW_Plack

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Dave, most of the electric aircraft I see use large, slow-turning props to give the electric powerplants the best shot at generating thrust. Given its limits on prop diameter, I'm not sure the Bensen frame would be a good candidate.

If you built a gyro frame specifically to take advantage of a 72 - 80" prop, I think you could get airborne on significantly less HP, although it wouldn't likely get anywhere near 100 knots.
 

dabkb2

Dave Bacon
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I agree Paul, most of the electric aircraft I have seen have larger props. if the motor I am looking at actually has 60HP and can turn 4000rpm it might work.
 

dabkb2

Dave Bacon
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I got some more info, 60hp is only good until the motors or batteries get too hot then it will automatically turn the power down to protect the motors and batteries. No warning and you are going down, same thing I have with the Mac. It will take $15000 to find out if it will work, looks like I will wait another 5 years and see where things are then.
 
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