I have never had an issue breaking props on an enclosed whoop frame. What are the blades hitting?

Regarding the motor shaft issue, it's best to use a prop removal tool to get the old props off (or just snip a side with side cutters if you're replacing it), as holding the bell and twisting the prop can separate the shaft from the bell. Here is a video on the issue and how to fix it:

The props hit the ducts as they deform on impact. I can see the scoring on the inside where it's hit. Then the blade shears off cleanly at the base of the hub. These props are very brittle, I haven't seen ones like this yet.

Thanks for the video, this is exactly my issue with the same motors. I guess I'll need to keep cutting them off instead of twisting them, or find a prop wrench.

I'm going to try a different brand of props and see if it's any better.

(14-Aug-2022, 06:09 AM)Janz99 Wrote: Here are the current props I am using: 
https://rotorvillage.ca/hqprop-40mmx4-qu...-2cw-2ccw/

They also stock these props:
https://rotorvillage.ca/gemfan-1636-4-1-...-4cw-4ccw/

I'm wondering if these might be any more durable? I saw Lemonyleprosy was using the 3 blade version on one of his builds. In one of his latest crash he showed a picture of the blade folded over.  The HQ blades do not bend at all, they all shear clean off at the hub.  

The pitch between the two different props is significantly different, how much will this effect the way the quad fly's?

You’re gonna hafta be a bit more specific, most of my flights end in a crash.

I have had a number of bad experiences with 2.5”+ Gemfan props, so anything 2.5” or above I tend to go with HQ or Azure or  really *anything* other than Gemfan when possible. But, with some prop sizes I just can’t get the pitch that I want without going with Gemfan, and honestly, I’d probably be totally cool with Gemfan if their customer service didn’t completely blow me off.

Anyhow, sub 2.5”:
Those HQ 40mm are essentially 1.6”. Basically 1.6x1x4.
On my 75mm (40mm prop) whoops (my 2s+ ones- I’m running a variety of props on my 1s 75mm whoops, but they don’t need near as much thrust as my heavier 2s or 3s 75mm whoops):
I’m running Gemfan 1636 quad-blades (1.6x3.6x4) on my motors that can handle them, and Gemfan 1635 tri-blades (1.6x3.5x3) on my weaker motors.

With these tiny little props- yeah, the Gemfans are more forgiving in my experience. They tend to bend rather than shear.

Keep in mind that this is just from my own experience and I may be wrong- You’ve potentially got 3 main issues.
1: Props don’t have enough clearance from the ducts. You can fix that by trimming down your props. You can just clip them with a sharp doo-hickey, or, there are some 3d prints available that fit toe nail clippers that can help you clip your props all nice and even like.
2: Your combination of motors and props are too tall/proud, and stick up too high above your ducts/guards. If this is the case, anytime you crash upside down you’re gonna be rubbing your props on the ground- no point in having prop guards if this is the case.
3: Both of the above, and/or props that are too brittle.

I can’t find a proper motor data sheet for your motors. What I could find seemed to show that the 19,000kv version could handle GF 1635 tri-blades on 1s- which makes me think that the 10,000kv version should be able to handle those props just fine on 2s.

Can’t promise you won’t burn anything out, but, I’m running GF 1635 tri-blade props on 1102 11,500kv motors, and while they land a bit hot, I haven’t burned one out yet and I’m pushing them pretty damn hard. I wouldn’t try the 1636 quad-blades on my 1102 11,500kv, so I would suggest sticking with the 1635 tri-blades.

Edit- quoted you twice, can’t seem to fix it. Mods, helps! never mind, I fixed it.

Anyhow, regarding pitch: higher pitch means more thrust, but also more stress on your motor and esc. If your motor and esc can handle it, then higher pitch means MORE POWER! IE: quicker gain in height as you bring your throttle up, more responsive movement when you move a stick, faster potential forward movement, etc.

Hi Ryan,

First, nice flying. You have a really nice whoop and are doing a
good job of flying it. You are progressing nicely. Good Job 

Even though I run HQProp props on my larger builds, I mostly run
Gemfan props on the tiny whoops. Truth is, I rarely break a prop on
a tiny whoop. Yep, they bend sometimes, but don't break. I do like
the tri-blade props as I "think" they strike a balance. I have used
quad-blade, tri-blade, and bi-blade props on my tiny whoops and
personally, I don't see that much difference from one to another. 
The bi-blades are supposed to be more efficient, but I don't see that
much, if any, difference in my Fly Times. Try different ones; different
number of blades, different pitch. I do this until I sette on one that I
like the best for that particular quad.

As for motors, this might sound crazy, but I often buy them in sets of 
8 especially if the motor is different than I normally run or a special 
edition. Here is my philosophy on it. Often folks suggest to buy an extra
1 or 2 in case there is a bad motor or one gets damaged. OK. So, why
not go ahead and buy 2 more {saves on shipping if you had buy just 2}.
Now, if they are all good, you have spares. If one doesn't break, you have
enough for another build. Two quads. Now, if a motor breaks, you just 
pick which quad you want to fly and put the other one on the bench until
you get a new motor {just wait until you place an order and then add the
motor to it}.  

Well, the prop tool does work. However, I find that a very small
flat blade screwdriver works pretty good as it is thinner than the
prop tool.

So far, I have never had a shaft come loose on a motor, however,
I use GEPRC motors on my whoop build and I have a BetaFPV 
Meteor 65s. I wonder if the shaft issue is specific to HappyModel 

Guess I need to build more whoops. Well, winter will be here 
in a few months. 

Thanks for all the kind words and suggestions guys, greatly appreciated.  

I found some Loctite 638 bearing retainer in my cabinet and managed to get the motor apart after some curse words and finally some heat. 638 is generally used for larger gaps but I figured it couldn't hurt to try it and see if it worked. Everything is back together and I'm charging up some packs for a test flight.  In the mean time I also ordered another set of 4 motors like IFLY suggested. They are coming from Aliexpress, so they will take some time to get here.  

I originally ordered 4 sets of props with all the parts for this quad build and we have blown through all but a single prop now.  I think I'm going to order another set of these HQ props along with some Gemfan 3 blade and 4 blade.  I did check the motors after a flight with the HQ props and they were cool as a cucumber. I'll keep an eye on it when we experiment with the other props.  With how porky this build is and the type of flying we want to do, I don't really see a bi-blade being a great option? I also made up a little board with the nail in it to install props like mentioned in the video V-22 posted.  I'll most likely keep cutting the props off until I get a chance to try a prop tool and see if it works any better.

There is only around .05" (1.2mm) of clearance between the ducts and the props.  So not a lot of room for deflection, might need to make up a little tool to clip them if this keeps being an issue.  With the profile of these props, the center portion sticks up past the ducts slightly.  So as mentioned, the stack height of the motor/props is a little tall for this frame.  Not sure if there are other 75mm whoop frames I could look at that might provide a bit more protection?   

One thing that having a tiny whoop has brought to light, is the need for a parallel charging board.  It feels like my life only consists of charging and storaging batteries.  With only 3-4 min flight time and only having 4 batteries we are constantly charging batteries. I ended up ordering the JB signature board as it has both xt30 and 60 plugs, poly fuses and a voltage checker.  Hopefully it works well.

Looks like the motor repair worked well! We blew through the last 2 props we had unfortunately.  You can see in the pics what I was referring to by the blade shearing off at the hub.  If you look close you can also see the tips of a few of the other blades that have been scuffing the sides of the ducts. 

This last prop, my son bumped the last stair as he was going from our basement to the main floor.  I wouldn't say he was going particularly fast but still managed to shear off a blade.....

Yeah, that shouldn’t be happening.
I’d definitely use different props or at least trim them a mm or two shorter.

Congrats on the motor repair!

I haven’t used the frame linked below, so I can’t speak to its durability, but it appears to have a fair amount of clearance from the motor mounts to the top of the ducts:
https://smile.amazon.com/gp/aw/d/B08J7LY...p13NParams

Edit- also, all of my mobula/moblite frames came pretty warped. I think I recall a video about boiling or steaming it to straighten it out? Maybe try to find a video of someone straightening a warped Mobula frame before dunking it in boiling water though.

Hi Ryan,

Well, you might consider one of these things:

As a quick test, you could try some Gemfan 35mm Tri-Blade props.
Yes, these props are just a little smaller, however, it would be a good
test, they might fly bettery than you would think, and you wouldn't
need to "cut" them off. It is a cheap thing to try and you don't have
to dismantle anything. {Personally, I would try this first}.

Another option would be to buy a different frame and transplant all the
parts to that frame. Unfortunately, I do not have an alternate frame
recommendation that uses 3 bolt motor mount pattern. In fact, I am
having problems finding 75mm 3 bolt whoop frames. Most of the frames
in this configuration are HappyModel which is what you already have.

BetaFPV does have a 75mm whoop frame that accepts both 3 bolt or 4 bolt
motor mounting patterns. Beta75X whoop frame.
But not sure it would if it would be any better  
{this would likely be my second option}.


You could raise the motors. I am assuming that the motor mount takes 
M2 bolts. I have assorments of small brass M/F standoffs which
can be screwed into the motor mount holes then mount that assembly 
onto the frame. I used this method on two of the motors on my Rescue
Quad to allow prop clearance as I am running 7 inch props on a 6 inch
frame. See This Picture. {this option works well with CF frames, but
I am not sure how well it would work on a plastic whoop frame}.

Thanks for the suggestions IFly4rotors, I placed an order for various 3 and 4 bladed props last night. Id like to try this before I start exploring some of the other solutions. I should have ordered a set of bi-blades just to see what they were like in comparison to the 3/4 blades, next order Ill grab some.

I honestly just think its a material issue on these particular props. When I look at some of my 3.5" props and the abuse they take in comparison to these, its a night and day difference. I've folded blades in half, not had a replacement, so then just folded it back and kept flying for the pack. If you look at these HQ 40mm props the wrong way they will snap a blade off lol. When I cut the hub, they are so brittle I don't need to cut very deep before the plastic basically shatters around shaft.

I ventured into acro mode yesterday for a few minutes during one of my flights.... wowsers is that tricky indoors. I'm not sure how some of these guys like Nick Bruns and Dax on YouTube can fly around their houses that fast in acro mode. My son fly's angle exclusively, even on the larger quads, and has had no problems picking up this tiny whoop. I've struggled making the transition back and forth. Maybe I need to spend more time playing with the rates to tame down this wild beast.

For me, taming the Meteor 65s was a simple throttle limit which ended up being 65 percent.

(16-Aug-2022, 01:49 AM)iFly4rotors Wrote: For me, taming the Meteor 65s was a simple throttle limit which ended up being 65 percent.

I put a bit of expo in the throttle right at the hover point, that really seemed to help flying indoors.  The pitch/roll/yaw rates still seem a bit touchy, but maybe a bit more expo will help there as well.  Props should be in this week sometime, we'll keep playing with it. I'm confident we can get it where its pretty comfortable to fly.

I see a few possibilities here. Your quad is heavier than what that frame is used to, so a crash is compressing the ducts farther than what would normally occur. I say that from the major gouging I see in the pics in the back of the ducts.

I use lots of different HQ props and haven't had a single one snap a blade off but then, I have rather light whoops. I don't think I have used the particular one shown in the pics and possibly they are from a bad batch (too brittle). I would try a few different props first and would not worry about bi-blades. The more blades, the more thrust, and you have a heavy whoop for 75mm so it will take more throttle to get it in the air although thinking about it, bi-blades may tame it down a little more and are a little more efficient (more flight time?).
I have also had no problems with Gemfan props.


I still think the problem has more to do with the weight. A small to medium crash with your quad, would be more like a full out crash with a typical whoop.

Hope the new props bring better luck...

I’d suggest not adding expo to pitch/roll/yaw. As your flying skillz increase with experience, having expo on those axes (I had to google this- apparently the plural of axis is axes- this language is stupid) could become a hindrance especially with muscle memory. Having expo on throttle is less of an issue because throttle response on every quad is going to be different depending on your motor, prop, and batteries- but your roll rates shouldn’t vary near as much.

When it comes to your rates (by rates I mean how fast or responsive your quad is to stick movements- how fast it will rotate on each axis according to stick deflection)- you can setup different rates on a spare switch. This way your son can have faster rates if he can handle them, and you can have lower/slower rates if you need them. If you put it on a 3-way switch, you could have a nice middle ground between the two as well.

The video below is a bit old, but is still applicable to BF 4.3.x:



I’m lifting 100g auw on my 2s and 3s 75mm whoops with no issues with 1635x3 and 1636x4. On my 1s ducted whoops I do typically have to trim my props down a bit to keep them from rubbing, but I haven’t had an issue with shearing off a blade because it rubbed in a crash- and they are all significantly heavier than a typical 1s 75mm whoop build. I think it’s a prop issue- bad material, bad batch, whatever- but this is just my humble opinion.

(16-Aug-2022, 03:39 AM)brettbrandon Wrote: I see a few possibilities here. Your quad is heavier than what that frame is used to, so a crash is compressing the ducts farther than what would normally occur. I say that from the major gouging I see in the pics in the back of the ducts.

I use lots of different HQ props and haven't had a single one snap a blade off but then, I have rather light whoops. I don't think I have used the particular one shown in the pics and possibly they are from a bad batch (too brittle). I would try a few different props first and would not worry about bi-blades. The more blades, the more thrust, and you have a heavy whoop for 75mm so it will take more throttle to get it in the air although thinking about it, bi-blades may tame it down a little more and are a little more efficient (more flight time?).
I have also had no problems with Gemfan props.


I still think the problem has more to do with the weight. A small to medium crash with your quad, would be more like a full out crash with a typical whoop.

Hope the new props bring better luck...

Last week while I was putting props on I was looking at how the props could rub/gouge the ducts.  From what I can tell, the motor mounting area is moving around, either from the thrust/weight of the quad or from the crashes.  Most likely its happening in both scenarios, under high load like a punch out or recovery and from smashing into objects much harder than the frame lol.

I'm not overly concerned with the gouges, I haven't noticed it effecting the way it flies, its just less than convenient having to replace props every battery pack. I re-watched Nick Burns video when he built one of these, he mentioned the same issue with the props as I'm seeing.  Hopefully one of the other 3 props I purchased will help with this.

At 1:47 he mentions the prop issue:


Thanks for the video Lemonyleprosy, I did notice the multi profile selection in BF, having it on a switch might be very helpful. I could probably give my son the quad with any rate profile and after a pack he would have it figured out and be flying just fine. He seems to be more resilient to change than I am at least. After making changes I always ask him how it feels, his response is always the same "feels the same Dad" lol......