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Lars Giertz's VMaxProbe (N1200M)

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Vector

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After further research, there is a old racer that shares similar properties as VMax Probe - The Sierra Sue - N12K. Does anyone know much about this aircraft/design?
 

lr27

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Well, it's certainly not as clean as the VMax Probe. But it was supposed to be reasonably fast.
sierra sue model article with picture.jpg
I thought I had more on it.
 

Himat

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Can you speak specifically of what the drivetrain issues was all about. How do you suppose electric fixes this?
Mini Imp drivetrain is mostly about torsional vibration. Search this forum for torsional vibration and you get some hits.

The Mini Imp have been discussed before, here are some threads:
http://www.homebuiltairplanes.com/forums/showthread.php?t=2391
http://www.homebuiltairplanes.com/forums/showthread.php?t=23479
http://www.homebuiltairplanes.com/forums/showthread.php?t=24041
I'll think there are more
 

larr

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Well, I'd never known about this plane before this thread. So for anyone else in the same boat:
jun1-2 lars VMaxProbe.jpgjun1-1small.jpg
Lar's web site (I think)http://www.webcamsue.nl/vmax.html
The NTSB report noted directional stability problems (yaw) during take off, so that points toward low speed control issues under full power. That would seem to lead to extreme problems in a low speed low power condition.
It was fast, but unflyable. Probably a good case for wind tunnel testing before actual flight.
 
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Kyle Boatright

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Well, I'd never known about this plane before this thread. So for anyone else in the same boat:
View attachment 59443View attachment 59444
Lar's web site (I think)http://www.webcamsue.nl/vmax.html
The NTSB report noted directional stability problems (yaw) during take off, so that points toward low speed control issues under full power. That would seem to lead to extreme problems in a low speed low power condition.
It was fast, but unflyable. Probably a good case for wind tunnel testing before actual flight.
I would lean towards the assumption that the airplane was a single point design and was inherently difficult to fly. Which is exactly why a more experienced pilot would have been appropriate. The NTSB report indicates Mr Giertz's total time was <300 hours, which isn't a very good basis to start from in conducting the initial flight in something as radical as the Vmax Probe.
 

Vector

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300mph @ 100 hp.
Were I to have the time and patience, I think such a design could be improved upon in some of the deficient areas. That will include a crash worthy frame and flight controls with more surface area. Also, an adequate baggage area for oxygen tank and the occasional weekend luggage for one pilot/occupant. There might be a need for a bigger engine if the level of performance previously advertised is the goal. 300 mph is very impressive.
 

karoliina.t.salminen

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My RC plane Skywalker X8 flips over on landing if stalled with full stall, due to reynolds number effect.
The NLF 414f + low reynolds number is not very good combination. I think the Vmax probe would have been safe with low reynolds number airfoils and a little larger cabin to fit the helmet for the pilot. Also there really should have been a roll cage. What was thought in designing a plane that way that when inverted, it will be head first on the pavement, I just wonder. Performance is great but safety should not be compromised for performance.
 

BBerson

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Most pilots don't wear helmets. Nor do glider pilots in similar cockpits, as far as I know. I doubt a half roll with inverted impact is survivable even with a helmet.
I certainly agree that a tip stall is a design flaw that needs to be avoided.
 

BJC

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I wouldn't call the items being discussed here as design flaws. I did not know the designer / pilot, but machines designed by racers for all-out speed, especially in a light weight category, will always be short on safety features and, likely, docile handling. There is a huge difference between a sport aircraft and a single point (in this case, maximum speed) design.


BJC
 

litespeed

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Yes ,

Single point designs can be bleeding edge stuff and can be very tricky esp for a newer pilot.

If he was in a Ar5 which is a similar weight class record breaker he would have had much better protection and more benign handling.
 

Monty

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I wouldn't call the items being discussed here as design flaws. I did not know the designer / pilot, but machines designed by racers for all-out speed, especially in a light weight category, will always be short on safety features and, likely, docile handling. There is a huge difference between a sport aircraft and a single point (in this case, maximum speed) design.


BJC
These are design features for the stated goals. Lars was not designing a sport plane. Try getting too slow in the Nemesis NXT on short final......
 

Topaz

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I wouldn't call the items being discussed here as design flaws. ... but machines designed by racers for all-out speed, especially in a light weight category, will always be short on safety features and, likely, docile handling. There is a huge difference between a sport aircraft and a single point (in this case, maximum speed) design....
Sure. And one of those differences is that bleeding-edge, "point" designs, trying to push some performance parameter, are quite a bit more likely to crash in the first place. When such aircraft are "short on safety features", as you say, the result is predictably much as we have here.

I don't see how it's somehow more acceptable to have a dead pilot just because he was trying to "push the limits". Pretty sure his friends and family probably would think otherwise. A complete lack of safety features in a highly-experimental and "performance pushing" aircraft is exactly the opposite of the reason we install safety features in the first place. Seems to me you'd want to include safety features proportionally to the risk of accident, rather than the opposite.

Clearly your mileage may vary.
 

BoKu

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...I don't see how it's somehow more acceptable to have a dead pilot just because he was trying to "push the limits". Pretty sure his friends and family probably would think otherwise...
I see it that way as well, but I fully respect that some might not. Now more than ever before, gambling your life in the pursuit of excellence is pretty much the only shot many folks have at rising above mediocrity--or worse. And not everybody has the resources to cover their bets for every possible outcome.
 

Topaz

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True and true. But you'd think they'd take basic precautions. The addition of another inch of headroom wouldn't have cost the Vmax Probe but a couple of knots, maybe, and just maybe Lars would've still been around to savor his triumph, instead of being a footnote to a footnote.
 

TFF

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That inch could also be the difference of breaking the record or not. No need to build the plane if it's not going to break the record. It gets to the point with performance, you can't keep improving without giving something up. The kind of dedication to break records is high because there is only one purpose. If beating the record is relatively easy, the bar is on the low side. Not saying the man ,if he knew,would have given up his life to do this, but he wanted to push to that edge.
After WW2 auto racing had lots of fatalities, and they were tolerated because they had just come off the war where there was a lot more death. Racing was not as dangerous as war. As the time from the war got larger, drivers or spectators getting killed were less and less tolerated. 60s and 70s was when safety had to be considered as much as speed. I think we are more shocked today when someone would really lay that type of dedication down for something actually unimportant.
 

Topaz

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That inch could also be the difference of breaking the record or not. No need to build the plane if it's not going to break the record. It gets to the point with performance, you can't keep improving without giving something up. The kind of dedication to break records is high because there is only one purpose. If beating the record is relatively easy, the bar is on the low side. Not saying the man ,if he knew,would have given up his life to do this, but he wanted to push to that edge.
After WW2 auto racing had lots of fatalities, and they were tolerated because they had just come off the war where there was a lot more death. Racing was not as dangerous as war. As the time from the war got larger, drivers or spectators getting killed were less and less tolerated. 60s and 70s was when safety had to be considered as much as speed. I think we are more shocked today when someone would really lay that type of dedication down for something actually unimportant.
Do I really need to point out the obvious? Sure, that extra inch may have cost him the record - may have. But the lack of it certainly cost him the record, since he's now dead from a crash that that extra inch might have helped him survive, and the record completely lost to him, forever.

It's all well and good to say, "maybe", but I'm more of the opinion that "maybe" is one hell of an epitaph, and not in the good way.
 

Monty

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Do I really need to point out the obvious? Sure, that extra inch may have cost him the record - may have. But the lack of it certainly cost him the record, since he's now dead from a crash that that extra inch might have helped him survive, and the record completely lost to him, forever.

It's all well and good to say, "maybe", but I'm more of the opinion that "maybe" is one hell of an epitaph, and not in the good way.

It was his choice to make. You make your choices. Respect his.
 
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