NMPRA

Can I use any motor shaft in an EF-1 Approved Motor? Long story short I'm left only with a Rimfire EF-1 motor which works but the OEM shaft doesn't support reversing. The shaft from a Hobby King NTM EF-1 motor is the right diameter, length and has a snap ring on the end which will allow me to reverse the motor.

Can I use the HK shaft with the Great Planes motor or is that in violation of the rules?

Chris

Parts cannot be swapped between different mfg's motors. Therefore you cannot perform the shaft exchange as you describe.

Dan Kane

Thanks Dan. I'll pull the motor out of my box then.

Sucks as there are no OS motors to be had, the two Hobby King NTM motors I own have issues with the bell spinning on the shaft, the Brodak motors I have are crap and I'd have to space the Rimfire out another half an inch to get the bolt on prop adapter to the proper distance for the cowl/spinner. That leaves the Eflite motor for me to try, right?

Guess I'll run the better of the two NTM EF1 motors I have and pull everything apart in between races to ensure that the grub screw is tight and the bell isn't spinning. Fortunately the Rimfire motor works in stock configuration on the nose of the Scarlet Screamer which I just completed to replace my crashed Invictus.

Chris

Question for the rules committee, is it legal to reverse the shaft on a Rimfire? I had heard it was ok by some, but then others suggested that you cannot.

-Joel

Rimfire EF-1 motor I have 1 I reverse the shaft on mine. I you have to do is take it out and cut a snap ring grove on the end which will allow me to reverse the motor. Also it will need a flat spot for the set screw too. It took me all of 10 min.

All:

The NMPRA has talked with MFG of the Rimfire motor, and they do NOT recommend turning the shaft around. Therefore, the NMPRA cannot support this modification.

In summary, NO you cannot turn the shaft around and you definitely cannot modify the shaft by cutting a groove or by replacing it with your own shaft.

The NMPRA is aware this may not be a popular decision. However, we need to be consistent with the MFG's recommendations.

DK

Danny at a quick look can you tell if some one had done it?
And I have run the motor for over a year now,and has worked fine.

You can make your own with this,
http://www.mcmaster.com/#catalog/121/3732/=vlzug7

88625K64 2 Each Multipurpose O1 Tool Steel, Tight-tolerance Rod, 5mm Diameter, 3' Long

Just make it 13mms longer then stock.And use the collect.

Kevin,
Does it matter if it can be detected or not? The rule clearly states the motor shall be "in stock configuration as provided by the manufacturer". If it's not as provided, it's not stock.

There was no performance advantage. If so what is it Please let me what got improved on?

So something should only be illegal if it's a performance advantage? Why did you modify it?

Gary,
There is a good reason to want the Rimfire shaft reversed. It's so we could use a spinner with the same 5mm collet as all the the other motor mfrs. (im not sure of the Hobbyking or OS motors) The Rimfire uses a knurled prop hub against the spinner backplate, both aluminum, Its hard to tighten the prop when it slips. Also, I have an assortment of good collet spinners that cant be used with it.

Chuck Anderson
OKC

Chuck

You cannot modify the motor and the MFG does NOT recommend you turn the shaft around.

The NMPRA cannot support a modification that the MFG doesn't recommend.

What do you want to happen?

DK

Dan,
Im not saying we should break the rules. I was just answering Garys post as to why someone would want to change it. It would be great if all mfrs had uniform standards in this respect. ll probably not use the Rimfire on future EF1's for this reason. Its difficult to fit it into some cowls and it moves the CG forward too much.

Chuck,

During the approval phase of this motor the NMPRA strongly urged them to change the shaft for those very reasons. RIMFIRE point blank refused. The NMPRA is very small and we provided no money for this product and therefore do not control it. We accepted it as is, because we wanted competitors to have options. The NMPRA cannot be responsible for what a MFG does or does not do. Nor can we be responsible for what some person may or may not do. All we can do is provide guidance. We made a decision based on the information we have and we did it to the best of our ability.

I do not own a rimfire motor. I did see two motors installed in PHX 2 weeks ago. Both used the bolt on adapter and non-collet style spinners. I didn't see any issues or hear of any problems. I am not saying they don't exist, I am saying I have seen the adapters installed and used in the only two examples I have ever seen.

DK