Bell 407 / Chadwick Vxp............

[DGP]

MY preference is the 8500...the soft wear seems easier to follow...has the same features as the rads...you can cancell out what ever you don't want to play with..have not heard of this new box by chadwick...only ever had our 407 fly like glass for about 6 mths ..and as we spray with it the blades and drivetrain take quite a beating...ie lots of turning with lots of weight on board..every liftoff is at max internal gross..stands up well though...not any problems other than it needs tracking after the season...have only changed one set of u-joints and one pitch change bearing from the pitch links in 10 yrs

[Heliian]

The VXP can do anything any other balancer can and then some. If you're not set up for the optical tracker (fasttrak) then you can still use the strobe gun and tip targets, or both. I've had great success with the system on the 2 and 3 bladed machines. Also a big fan of the 2000, it's more simple but effective. ****, the 177 is still used throughout the world today.

[Cambox]

I don't doubt any of your statements, but back to my original question........... How have you found the VXP on the 407? Actually I don't seem to be getting any good comments on any track/balance equipment on the 407..........

 

R...

 

The VXP can do anything any other balancer can and then some. If you're not set up for the optical tracker (fasttrak) then you can still use the strobe gun and tip targets, or both. I've had great success with the system on the 2 and 3 bladed machines. Also a big fan of the 2000, it's more simple but effective. ****, the 177 is still used throughout the world today.

 

[Cambox]

Well, it looks like any experience has been exhausted. Seems like either few 407s, few VXPs or very little use of either

 

Thanks for the replies guys, appreciate them

 

Rick

[quadotter]

My guess is that not a lot of people use the vxp because it costs quite a chunk of change. The RADS-AT is pretty expensive too, but people say it's the only way to go for the 407. Then again fuel and airtime are pretty expensive too... not to mention the down time.

 

I've used the VXP on the 407 a few times now to the point where I've learned what to do and more importantly, what not to do. It's great at gathering data and displaying it (good user interface utilizing a pc) but not so great at computing solutions. It displays the track pattern for different airspeeds graphically and numerically which is kinda sweet. But you have to know what you're doing in terms of solutions and be familiar with how the 407's blades fly (and how twitchy they can be). For instance, using pitch links and tabs in hover and flight regimes seems just crazy too me but that's what the solution often tells you to do. I do it old school, by setting up track at ground idle with pitch links only, then spinning it up to 100%Nr and seeing what i've got for track. Usually, I start using tabs after that. If you select Track mode in the vxp, and get the track as close and consistant as you can, then the results are usually pretty good. But, you have to put some thought into your moves, because the solutions given by the computer are often questionable. Often it can give helpful solutions, but only if you select one variable at a time ie pitch links or tabs, or weight, Hope that helps.

[ray]

I had to track and balance a Bell 427, which I believe has the same rotor head as the 407.

I had never done one before, being from an A-Star background.

 

I used a RADS system, and had never used one of those before either, but being really familiar with the Chadwick systems.

 

The rotor system was dead smooth in about 3 or 4 runs. Made the moves exactly as instructed by the box. Worked out well.

 

For what it's worth.

[kopterdoc]

I was also having trouble with the 407 m/r until a guy at Alpine told me to ignore the track. From then on I have always told the balancing equipment to do balance only and it has worked every time since then with very few runs. This works very well with the 8500. I repeat, do not install the camera, do not paint the bottom of the blades and on initial setup turn off the track. Don't worry about the track on a 407. That is for 2 bladed Bells. Unless you are installing new or repaired blades, only then I would track them first and then do balance.

[BAH]

I was also having trouble with the 407 m/r until a guy at Alpine told me to ignore the track. From then on I have always told the balancing equipment to do balance only and it has worked every time since then with very few runs. This works very well with the 8500. I repeat, do not install the camera, do not paint the bottom of the blades and on initial setup turn off the track. Don't worry about the track on a 407. That is for 2 bladed Bells. Unless you are installing new or repaired blades, only then I would track them first and then do balance.

 

This is very interesting, we use RAD's and do the exact opposite. Get the track down to less that 4mm, then look at balance.

[quadotter]

The vxp is very good at collecting and presenting the data, but completely useless at computing solutions because the application cannot correct the clock angle i.e. it can't learn. Best to develop your own polar chart with move line axis' for both pitch links and tabs for a specific set of blades at a specific airspeed. One can do this by making a positive pitch adjustment on a given tab or link and recording the resulting move line. Best to do that on a reasonably balanced rotor to get an accurate move line clock angle for future reference. Seems not uncommon to have track splits of 10 mm or so in order to get all blades producing more or less the same lift. I get why Bell wants you to bring the ground track down to 4mm or less, but it seems a waste of time to be picky about that if one is going to make pitch link adjustments later on in order to get rid of vertical vib. The track info is good to have but the primary focus needs to be on the polar chart and where the move line is going.