Failed prop hub on 1700mm p-51 hub

[Scottchman]

has anyone had a prop blade let go or fail on the 1700mm P-51 Mustang by motion RC. I had one let go at about 3/4 power. I had sent pictures of lateral cracks coming from attach holes, bent screws common to the root or inboard location on the Prop Blades. Brand new spinner assy. and blades in the assembly that failed.

[Beeg]

I've been waiting to buy one of these but after reading the thread at RCGroups I've been hesitant. Since this planes inception there has been prop/hub failures. I've read some guys are reinforcing their hubs by various means but don't know the longevity of those either. I'd just hate to spend that much money and have the plane totaled or seriously damaged by that kind of failure.
Also what I don't know is if it is the hub or blade roots that are failing? I know Aros and Brandon have had one the first ones. Hopefully they'll chime in with some words of wisdom.
Also, not sure of the current version of this model and if all the problems have been rectified by the manufacturer.

[CDN_Iceman]

has anyone had a prop blade let go or fail on the 1700mm P-51 Mustang by motion RC. I had one let go at about 3/4 power. I had sent pictures of lateral cracks coming from attach holes, bent screws common to the root or inboard location on the Prop Blades. Brand new spinner assy. and blades in the assembly that failed.

OMG this is too weird. I am sorry to hear about your prop blade but I had the same problem yesterday. The problem I had I installed this prop and hub on my VQ Focke-Wulf FW-190. As I increased the throttle the hub just exploded and ripped my cowling off.

Now I am with out a plane for the war bird event I was going to attend this week end. Clearly there is an issue with this hub. While I am sure you will get support I don't think I can expect any help. I have to rush in a brand new fiberglass cowling.

Here are my before and after pictures. As you can see the plane never made it off the bench.

Jeff

[Blewbayou]

Keep us updated, I'm getting ready to maiden mine in a week or 2.
I wonder if over tightening or not tightening enough is the reason or uneven tightening.
I balanced the back plate, then the back plate and spinner together and finally, I balanced the whole thing with blades installed. Weighed the blades, all 4 were spot on. I could see where any imbalance in the whole unit could cause it to disenagrate being so big and heavy.

[Blewbayou]

I'm wondering if putting some epoxy between the blades and back plate would solve the exploding props?

[dkalwishky]

I've got the 1700mm Mustang and I have not had any issues with mine. I did the zip tie prop mod to mine and so far so good. I did buy a bigger motor for the plane so I can go back to an unmodified prop. I feel the stock engine doesn't have enough power to fly the plane, I always felt like it was going to stall in turns (it never did). With the motor upgrade or prop mod she flies much better.

[CDN_Iceman]

I've got the 1700mm Mustang and I have not had any issues with mine. I did the zip tie prop mod to mine and so far so good. I did buy a bigger motor for the plane so I can go back to an unmodified prop. I feel the stock engine doesn't have enough power to fly the plane, I always felt like it was going to stall in turns (it never did). With the motor upgrade or prop mod she flies much better.

Can you provide me with more information regarding the zip tie prop mod please or provide a link for me to read about it. Also I did check the balance of my prop and it was good. As for being over or under tightened I had securely tightened the spinner to the shaft.

This does seem weird though that two people had the exact same problem. I am just disappointed about my please. I was finishing this plane so I could buy the Motion RC Spitfire.

Jeff

[RCjetdude]

It is the same way on the 1700mm Corsair. I weigh each blade to the grain so they are all the same. Then install them on the hub and check balance. Then I run thin CA down into the hub and around the blade clamps to lock it all together. I have not had any problems with doing it this way. Motion sells them but FMS makes them.

[dkalwishky]

Can you provide me with more information regarding the zip tie prop mod please or provide a link for me to read about it. Also I did check the balance of my prop and it was good. As for being over or under tightened I had securely tightened the spinner to the shaft.

Jeff

Hobbysquak forum link:

https://www.hobbysquawk.com/forum/rc-airplanes/propeller-airplanes/36792-what-is-the-prop-zip-tie-mod

YouTube video:

https://www.youtube.com/watch?v=QksnbavFSwg

[Beeg]

Can you provide me with more information regarding the zip tie prop mod please or provide a link for me to read about it. Also I did check the balance of my prop and it was good. As for being over or under tightened I had securely tightened the spinner to the shaft.

This does seem weird though that two people had the exact same problem. I am just disappointed about my please. I was finishing this plane so I could buy the Motion RC Spitfire.

Jeff

v8truckin's Prop Mod

https://www.rcgroups.com/forums/showthread.php?1501476-FMS-North-American-P-51-D-Mustang-1700mm-%2867-inches%21%21%21%29/page130#post21017245

https://www.rcgroups.com/forums/showthread.php?1501476-FMS-North-American-P-51-D-Mustang-1700mm-%2867-inches%21%21%21%29/page158#post21110696

[Beeg]

It is the same way on the 1700mm Corsair. I weigh each blade to the grain so they are all the same. Then install them on the hub and check balance. Then I run thin CA down into the hub and around the blade clamps to lock it all together. I have not had any problems with doing it this way. Motion sells them but FMS makes them.

On the Corsair hub I don't think it's as critical. I'm not so sure using CA on the hub to balance it is a good idea as I've had two failures on my FLRC P-38 but one failure was definitely my fault for flying after a mild prop strike. The other side just let go one day and I can only surmise that maybe the CA on these types of hubs caused brittle areas that are prone to cracking. Although my current set on the P-38's have held up fine so far.

I do know some guys with the P-38's are completely filling the back of the spinner hub with epoxy to give it added strength. Some are also adding fiberglass or CF into the epoxy mix.
Here's the post that TiredIron posted filling his P-38 back plate with epoxy:
https://www.rcgroups.com/forums/show...4#post37112849

Here's another post by cri.cri56
https://www.rcgroups.com/forums/show...4#post37429204


I do like the new Spitfire hub assembly with the metal cross brace on top of the prop roots. At least this should hold the hub together if a single blade lets go.

[xviper]

I'm not so sure using CA on the hub to balance it is a good idea

You can be absolutely 100% sure that CA is NOT a good idea. CA makes plastics brittle and combined with too much torque on the screws, will create hairline fractures in the plastic.
I too, have flown my 1700mm Corsair for a couple of years and I've never had any problems with the prop assembly.
1. weigh each blade and make them all the same.
2. balance the back plate, hub assembly, spinner on a prop balancer and mark their relative position when assembled. Then try to balance the complete assembly if your balancer will take it.
3. DO NOT let any CA get near that assembly. Use a little FoamTac if you're really paranoid.
4. DO NOT put those blade screws on too tight.
5. There was a short period of time when FMS sold the wrong blades for certain prop assemblies (or maybe it was the customer who bought the wrong blades). They did not seat properly but people rammed those thing on till they seated. BAD IDEA.

[Beeg]

Yep, I agree. CA and Thread Locker on plastic = Bad juju :Crying2:

[Blewbayou]

Out of curiosity, what does the prop mod have to do with prop assembly not exploding? Doesn't it increase the amps?

[xviper]

Out of curiosity, what does the prop mod have to do with prop assembly not exploding? Doesn't it increase the amps?

It increases the pitch by lifting up one edge of the blade. This puts more stress on the blade, backplate. The bottom surface of the mounting section on each blade no longer can sit completely flush. If installed properly, it won't explode. If not, it will explode. The point is, if you have a stock prop explode due to some issue with assembly, then using the same assembly method will make a shimmed prop explode.
Yes, it increases the amp draw. You must ensure the motor and ESC are big enough to handle it. The thicker the zip tie, the more pitch, the more stress, the more amps.

[CDN_Iceman]

Thank you for the links.

[Blewbayou]

It increases the pitch by lifting up one edge of the blade. This puts more stress on the blade, backplate. The bottom surface of the mounting section on each blade no longer can sit completely flush. If installed properly, it won't explode. If not, it will explode. The point is, if you have a stock prop explode due to some issue with assembly, then using the same assembly method will make a shimmed prop explode.
Yes, it increases the amp draw. You must ensure the motor and ESC are big enough to handle it. The thicker the zip tie, the more pitch, the more stress, the more amps.

Ok, I just thought people were saying prop mod fixes exploding props, which didn't make sense to me.

[RCjetdude]

Now I am afraid to fly my Corsair.....:Scared:

[xviper]

Now I am afraid to fly my Corsair.....:Scared:

If you've used CA on the assembly, I would suggest you take it apart and inspect it with a magnifying glass for spider webbing. If none are found and you've got the thing well balanced and have never had a prop strike, you're probably OK and you didn't torque the blade screws overly much. Sometimes, CA will fracture plastic in a week (like what happened to me with plastic control horns) or it may take weeks or months if the plastic is thick and the CA was not near holes (like the screw holes under the blades - that happened to me but thankfully, the blade came off when I was just throttling up on the ground). I found out the hard way.

[dkalwishky]

Out of curiosity, what does the prop mod have to do with prop assembly not exploding? Doesn't it increase the amps?

Noting at all, I was not clear in my post. I meant to say that I have not had any issues then I started a new topic about the prop mod that deals with the performance of the plane.