Motor Question

GaryS · Post by **GaryS** » Thu Jan 29, 2015 3:39 am

I have a Rimfire in the Proud Bird I flew at last year's Winterfest. I can't remember having any issues installing the spinner or prop with the stock setup, so I really don't see the big issue.

As far as I know the motors aren't universal as far as mounting is concerned. Some are longer, some are shorter, I don't believe they all have the same firewall pattern (I know the ArrowWind I put in my Dara back in 2012 was different than the EFlite). Considering the differences I don't see why a different spinner/prop mounting setup is a big deal.

Dave Yost · Post by **Dave Yost** » Thu Jan 29, 2015 10:07 pm

I was going to put a Rim-Fire motor in a Shoestring, wanted to use the E-Flight spinner. To do this, you must turn it around to get it to match the cowling and fit with out a complete motor box re-design. Glad I saw this post.

As long as there are no form, fit or function changes, why would the NMPRA care how it is mounted? Forces the airplane designer to build around the motor instead of being able to test multiple motors and forces people who own a particular airplane to stick with the OEM motor........Seems rather subjective.

So, you can wire the carb open, remove the spring on a TTpro.40, but can't turn the shaft around on an electric motor because that changes the configuration? By that logic, back plate mounts on a TTPro.40 should be disallowed(?).....The helicopter, glider, F5D, 3D and Pattern guys would all find this rule rather archaic .........

Food for thought.

Dave

cbk07 · Post by **cbk07** » Fri Jan 30, 2015 6:11 am

"Re: Motor Question
Postby kane » Fri Jan 23, 2015 10:10 am

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. "

Dave, read above. If the manufacturer has told the NMPRA that they do not recommend turning it around, then how can the NMPRA support it.....especially if they are not recommending it for safety concerns? I can not imagine why the manufacturer has stated this, but they clearly have. I can fully understand why the NMPRA wishes not to go against manufacturer recommendations

Dave Yost · Post by **Dave Yost** » Fri Jan 30, 2015 1:05 pm

Well, I think the NMPRA should drill down a little further, because the 35mm, 42mm and 50mm motor tech data on GP's web site gives part numbers for the alternate collet assembly and shows both mounting methods. (?)

I get the safety piece. However, If their own tech data provides, who was the Product Manger at GP who specified otherwise and how come the instructions for the GPMG4630 (specifically) are not posted on the web? My motor came with the 35MM data(two years ago).

Not trying to be a pain in the A$$, just would like some clarification. Was it a Tech.....Or Product Line Manager that provided the data? ....and if it is indeed a safety issue, where is the supporting documentation?

This does not pass the sniff test, the ability to turn these motors around is "industry standard".

Thanks, Dave

kane · Post by **kane** » Fri Jan 30, 2015 1:59 pm

"SNIFF TEST" seriously, what are you talking about?

Nobody said you can't mount your motor backwards. Nobody said you can't build a new motor box to do this.

The NMPRA has said DO NOT DISASSEMBLE YOUR MOTOR AND TURN THE SHAFT AROUND!

For the record it was a product manager and not a tech that said this.

DK

kane · Post by **kane** » Fri Jan 30, 2015 2:59 pm

For the record if someone wanted to run with an idea like this I don't have any reason to think this wouldn't work.

I drew this. This was my idea. I don't care if you copy it or sell it. I don't have a rim fire motor, I can't draw this to scale and see if it will work.

DK

Dave Yost · Post by **Dave Yost** » Fri Jan 30, 2015 3:39 pm

What I meant by sniff test: Over the years, I have received bum data on the phone or email from techs at both HH and GP. I usually have to go over there pay grade or to a sponsored pilot to get the real deal and my suspicions are usually correct. I did not intend to insinuate a conspiracy theory

sorry if it sounded that way.

I get the mounting arrangement, the situation I have was in order to get the collet to seat correctly and to get the proper spinner ring gap, I had to drive the shaft out the other direction about an 1/8th or so. I still have a collar on the back side and a set screw in the case, but the C clip has been left out.......leaving the c clip off or cutting a new groove is by definition an configuration change or modification respectively, correct?

(I know the answer, I will just ask to further T you off!

)

Cheers, Dave

kane · Post by **kane** » Fri Jan 30, 2015 3:58 pm

No you cannot cut a groove in the shaft. No you cannot remove the clip. No you cannot push the shaft out the other side.

As soon as Rimfire makes a comment regarding the whys and hows you guys can go after them.

Quite honestly, I don't get it.

In PHX, I watched a pilot, take a Rimfire motor, bolt it directly onto a shoestring. The main issue was finding screws and spacers long enough to make it work at the field (Jett long muffler screws and 6-32 blind nuts did the trick). But he did, and he used the stock adapter. Because he borrowed the motor from a Proud Bird pilot he used the 1.75" spinner that the other guy had. No issues at all.

I seriously do not understand what the big deal is. I get the issue with spinner not staying tight, I have had this happen to me while using Brodak spinners. The spinner was knurled and the collet type, prop adapter was knurled and the two didn't mesh. AND BECAUSE I CAN'T MODIFY A STOCK COMMERCIALLY AVAILABLE SPINNER, I switched spinners and no issues at all.

Even though this seems to be a small issue and the implications of changing out the shaft or turning it around are so trivial, you still can't do it. You guys are all smart guys, figure it out without going against the rules.

DK

Dave Yost · Post by **Dave Yost** » Fri Jan 30, 2015 4:31 pm

Well, guess we beat that dead horse pretty good.........Moving right along, who is going to win the Supper Bowl this weekend? and what is the minimum PSI allowed in a regulation football?

Canderson · Post by **Canderson** » Sat Jan 31, 2015 12:01 am

Dan, What spinner do you use now?

kane · Post by **kane** » Sat Jan 31, 2015 9:01 am

Chuck

I don't have a Rimfire motor so I have no experience with that adapter and spinner. What I saw work was a metal backplate and a plastic cone with two screws to secure it, they are transparent or opaque. I don't know who sells them. They do look like the spinners that George Parks is selling prior to the modification.

In my case I went back to a collet type spinner because I had one. I was trying to avoid spacing the motor out further by using the collet type prop adapter with a thrust washer. Of course this was discovered at a contest when I had to change a prop and couldn't get the spinner off. I destroyed the cowl trying to get in there with pliers to hold the thrust washer while removing the prop. I ran an all plastic spinner for the first two heats until I found the right spacers and moved the motor forward. I think it was a Dubro brand.

Dan

Canderson · Post by **Canderson** » Sat Jan 31, 2015 1:45 pm

I hate when that happens!

RCjunkie · Post by **RCjunkie** » Sun Feb 01, 2015 2:22 am

"SNIFF TEST"
The NMPRA has said DO NOT DISASSEMBLE YOUR MOTOR AND TURN THE SHAFT AROUND!
It can be done with out taking the motor apart. Just place the new 5mm shaft in and puss 1 out with the other 1. Did not take it apart!!!!!!

GaryS · Post by **GaryS** » Sun Feb 01, 2015 5:33 am

If the original and replacement shafts aren't exactly the same, from the same manufacturer with the same part #, in the same orientation as the motor originally came from the manufacturer in, it's not in the same configuration it came in and therefore it's not legal per the rules...whether you disassembled it or not.

Dave Yost · Post by **Dave Yost** » Sun Feb 01, 2015 2:58 pm

So, in summery:

Buy a motor, spinner, collet and prop. Put it all together without removing any parts. Ensure the collet is seated and you can not pull the spinner/prop off with your hands. Next, design your motor box and cowling around that. If it is an ARF and you are using something other then the OEM recommended motor and collect assembly, there is a 50% chance you are screwed.

There. Done.

(Sorry Dan, could not resist

)