Do you have to peel labels off 24mm Qjets?

[4regt4]

Will be using a bigger field, want to kick it up a notch. So I ordered some "D" and "E" Qjets. But they will not fit in the motor mounts of any of my rockets unless I remove the labels.

Measurements: Estes 24mm motors are 0.930" diameter. Qjets are 0.941 with the label, 0.933 w/o. It's just enough to make a difference. Without the label, they are basically a friction fit.

Anyone else run into this?

Hans.

 

[DigBaddy]

Yeah, some are a bit snug. Peel the label.

 

[Bill S]

I haven't had to. I just checked the fit of some D22-7s in some Estes BT-50 brown tube, no issues. The motors are a little snug when you put them all the way into the tube (mainly near the retainer ring), but I have had no need to remove the labels.

 

[4regt4]

Odd. I can't fit the Qjets into any of the 5 rockets I have with 24mm mounts. 2 are unflown, 3 have seen multiple flights - meaning that the mounts have seen some "stress".

Hans.

 

[Ulexis]

I had to peel the label the other day for a goblin.

 

[4regt4]

Thank God I'm not alone.

Hans.

 

[Initiator001]

I have been flying 24mm Q-Jet motors (D22 & E26) for almost a year now and I have never had to peel off the outer layer.

I have flown the 24mm Q-Jets in an 1985 vintage Estes Renegade kit, a clone of the Estes Maxi-Icarus I built in 2007 and an Estes Maxi-Alpha 3 among others.

One thing I have noticed is that if a lot of glue was used to attach the centering rings to the motor mount tube the tube will shrink slightly where the glue is located. This can make it hard to push in the rocket motor.

 

[kuririn]

After reading the initial post I tried it in an Estes Firebolt (E2X).
Had to peel the label to get it in.
Also because of the rear flange on the motor the plastic motor retainer doesn't work.
Tried it on a spare BT-50 tube and it is a snug fit with the label on.

 

[DabCat]

I flew one recently in an Orange Crush and had no issues. To be fair though, that's the only one I've flown so far. I have had label issues with the smaller 18mm ones though.

 

[Scott_650]

A snug fitting motor mount tube isn’t all that unusual - I have couple rockets where I have to give an Estes cardboard motor a light sanding for a reasonable slip fit.

 

[neil_w]

This is a good issue to raise in the Aerotech open thread.

 

[lakeroadster]

This is a good issue to raise in the Aerotech open thread.

It's talked about... but not resolved.

That's my one beef with AT SU engines. I almost always have to remove the labels to get the motor to fit into the MMT.

Hi Mike, that’s interesting and concerning. When we designed the molded cases, we deliberately reduced the case diameter by 0.005” to eliminate this problem. In theory.

Who produces the MMT in question?

Hard to know at this point. The two rockets I've flown 29mm SU's in is an NCR 1/4 scale Patriot that I swapped out the stock MMT tube since it was odd sized. I can't remember where I sourced it from (over a decade ago). The other is a Sheri's Hot Rockets Mercury Redstone. I've had it for years as well, so I can't recall if I bought it from Sheri directly or from Red Arrow Hobbies after she sold out to them. Either way, I don't know where they sourced their parts, could have been anyone's. I've designed some 3D printed parts for marking fins and such; they have to be sized for the largest diameters in any given "standard" sized airframe or MMT. I learned that the hard way.

I've attached a spreadsheet I put together of body tube dimensions from every vendor and source I can find. All I can say is there is no standard, ODs and IDs can be all over the board.

 

[neil_w]

The quoted discussion is not specifically regarding the 24mm Q-jets. Obviously it's all related, but nonetheless not quite the same thing.

 

[lakeroadster]

The quoted discussion is not specifically regarding the 24mm Q-jets. Obviously it's all related, but nonetheless not quite the same thing.

AT SU engines... plastic cases with stick on labels.

 

[crossfire]

I was told the early Q Jets had this problem it should be corrected with newer motors

 

[kuririn]

I was told the early Q Jets had this problem it should be corrected with newer motors

The early runs of the 18 mm QJets were slightly oversize for BT-20 tubes. They fit Quest T-20 motor tubes just fine, cuz they're slightly bigger. AT/Quest adjusted the casing size to remedy that.
The question is do they have the same problem now with the 24 mm motor casings?

 

[kuririn]

To be fair, the problem of fit extends to all motors, not just 24 mm QJets.
I've recently had to peel the paper from Estes BP mini motors cuz they will not fit my BT-5 motor tubes.
Perhaps humidity is an issue with paper motor tubes?

 

[DaHabes]

I always have to peel the labels on Aerotech SU motors. Whether you need to peel or not can depend on the tubes you use. The I.D.'s of tubes aren't exactly identical (e.g., LOC vs. Estes) and there can be some variance even within the same product line. These are paper tubes after all, not machined parts.

 

[samb]

Yes. And many Estes A10s.

 

[4regt4]

Just measured Qjet E26 again - without label and cleaned with alcohol to remove the glue.

It's tapered, about 6 thou bigger in the butt. So, without label it slid in OK for about 2/3 of the way, then got tight.

Hans.

 

[Back_at_it]

I've had this happen on a number of Aerotech 24mm and 29mm motors. A number of them will not fit in Estes BT50 tubes with the labels.

One word of caution. When you remove the label, wipe off the excess glue with alcohol if you ever want that motor to come back out of the tube. I flew one and the glue got hot and I ended up pulling the entire motor mount out of a big daddy.

 

[Tractionengines]

See my notes and photos in post # 4241 of the AeroTech open Thread. June 19, 2019. Along with a few following posts.

I tested the "fit" of 24mm Q-JETS vs 24mm other AeroTech SU motors, in a number of tubes and retainers. The Q-Jets fit in the Estes 29mm->24mm adapter, 24mm MMT, and 24mm retaiers fine. Other makes of parts are hit-n-miss as shown in the photos.

[ I hope this link takes you to the correct post. If not can someone let me know how to fix it to get to the right post. ]

https://www.rocketryforum.com/threads/aerotech-open-thread.125657/post-2149979

 

[ep29030]

FYI, I often peel the 29mm Aerotech SU motor labels to get them to fit. I've found that WD-40 does a nice job of softening the label adhesive. Spray a small amount on the label, rub it all over the label with your finger (or a rag), then let it sit a few minutes. Can even do it the night before and let it soak.

 

[4regt4]

See my notes and photos in post # 4241 of the AeroTech open Thread. June 19, 2019. Along with a few following posts.

I tested the "fit" of 24mm Q-JETS vs 24mm other AeroTech SU motors, in a number of tubes and retainers. The Q-Jets fit in the Estes 29mm->24mm adapter, 24mm MMT, and 24mm retaiers fine. Other makes of parts are hit-n-miss as shown in the photos.

[ I hope this link takes you to the correct post. If not can someone let me know how to fix it to get to the right post. ]

https://www.rocketryforum.com/threads/aerotech-open-thread.125657/post-2149979

I'm wondering (haven't actually measured) if MMT shrink somewhat in assembly. All my rockets so far have had the motor mounts assembled with yellow glue - so they have seen some moisture. But the Qjets don't fit in *any* of my assembled rockets with the labels intact. I'll have to try fitting into the BT-50 (24mm) tubes I have laying around.

Hans.

 

[Cape Byron]

To be fair, the problem of fit extends to all motors, not just 24 mm QJets.
I've recently had to peel the paper from Estes BP mini motors cuz they will not fit my BT-5 motor tubes.
Perhaps humidity is an issue with paper motor tubes?

Yes. And many Estes A10s.

I have this a lot with mini motors. Seems to be a thing.