Ejection charge recommendations. 4" T-LOC

[Tractionengines]

Building the 4" LOC "T-LOC" for my young daughter. We wanted the diameter big enough Stickerschock" could make the graphic wrap. My question is if anyone has this configued this as nosecone eject, not payload bay, and how much BP does it take? (I'll run the BP calculations, but looking for any "real world experience".)

The good thing is it's light enough at 2.4lbs to fly on smallish motors. The issue I am concerned about is if the small 24 & 29 mm single use motors (F32T, F42T, F44W, F52C, etc) will have enough ejection kick to them...

(I know "ground test" is best option, but I can't do that right now. And while I can "adjust" the charge in a SU motor; it will be a while before she is measuring and loading BP.)

Thouhts?.?...

Thanks in advance,
Mike

 

[Sandy H.]

Years ago (before the forum reset - guessing 2000-2001, not sure) I asked a similar question about making a 'big' rocket (Estes BT-80: 2.6") that was fairly long (4ft-ish). I flew it on a D12 and the nosecone barely came off and the rocket got damage when it touched down somewhat like a lawndart.

The suggestion I got from the forum was to learn about 'stuffer-tubes.' Basically extend the motor tube way up the rocket and put a centering ring at the top. This helps the parachute not slide further down than desired and also reduces the pressurized volume of the rocket. I followed recommendations and flew the rocket a handful of times on the D12 until it got stuck in a tree.

I'd say look into the stuffer tube option, as it could let you just use stock S/U and re-loadable motors without having to play with changing the amount of BP.

Just a thought. Never built the rocket you're talking about.

Sandy.

 

[waltr]

Good advice from Sandy.

As to motors, I'd recommend a F67W-6. I use this motor on my 1kg (2.2lb) Loc IRIS and give about 600 ft apogee. Also leaves the pad fast enough to be stable.
Run sims of the other motors check the velocity off the rod/rail.

 

[Handeman]

You might want to consider a piston. The 2.6 rocket I have flies on G and H motors. I have to reduce the powder charge of all motors to .4 to .5 g or it's too strong.

 

[TheTank]

Im on my second T-Loc 4. Tons of flights on them. The factory charges on the 29mm F67 are plenty and have no problem fully extending the factory cord to the point it bounces slightly. Factory charges on the 29/40-120 case and DMS motors like the G72 and G75 have all worked good as well. I dont have a factory DMS charge in front of me for a G right this second but I believe its between .6 and .75g… but fact check me on that.

 

[TheTank]

Just fact checked myself… opened a G75M i have in the shop. Over 1g in the provided charge.

 

[gtg738w]

The T-LOC is already very short as it is, should be fine on the smaller motors like John said. Any reason you're not just installing the bulkhead?

 

[Tractionengines]

Any reason you're not just installing the bulkhead?

Full wrap graphics from stickerschock, and my daughter didn't want the line from a split in the body. LOC says this can be built without the split...(mainly for long motors.), so that's how we did it.

 

[gtg738w]

Full wrap graphics from stickerschock, and my daughter didn't want the line from a split in the body. LOC says this can be built without the split...(mainly for long motors.), so that's how we did it.

Sounds like a fun build! Any pictures yet?

 

[Tractionengines]

Fins and nosecone are in primer. So it's all wrapped up.
But here is the "proof". Will have light purple nose and fins. Then fins will have a bright orange on the outside of the t-fins to help with seeing it. Don't laugh too hard...though I can't help but laugh every time I look at it. She is 6 and ALL ABOUT UNCORNS (and horses) for the last 2+ years

 

[TheTank]

Fins and nosecone are in primer. So it's all wrapped up.
But here is the "proof". Will have light purple nose and fins. Then fins will have a bright orange on the outside of the t-fins to help with seeing it. Don't laugh too hard...though I can't help but laugh every time I look at it. She is 6 and ALL ABOUT UNCORNS (and horses) for the last 2+ years
View attachment 488322View attachment 488323

I hear ya… my daughter is 5… needless to say, I have a few “Elsa” rockets… im waiting on the unicorn request.

I think I forgot to mention before, both of my 4” T-Locs are nose cone eject. Neither of my kits came with a bulkhead to seal off the upper bay at the coupler. I just assumed nosecone eject was the way it was supposed to be when I built them.

my kids both love the T-Locs.

 

[Tractionengines]

Fresh out of the paint shop....

 

[Zbench]

I found exactly 1.0 gram works flawlessly with my nose cone mounted apogee altimeter. Two flights in that configuration with no issues.

 

[Tractionengines]

Zbench,
I may modify NC and copy your design for the Apogee altimiter over the winter.

Looks like this weekends NOTRA launch in Amherst will be canceled. Temp 40F, low clouds, 25+% chance of rain, and wind at 20mph. Oh well, we have lots of stuff that needs done at the house.

 

[Tractionengines]

Finally flew this on July 2 2022 at NOTRA Launch. Flew on a G80-14NBT, with 1gram charge. It's a very tight nosecone fit. While it was a good flight and recovery. There was not enough "shock" to tear any of the masking tape bundles on the harness. I think I will lightly sand the ridges on the shoulder to get a slightly looser fit. It looks like a lot of charge went out the back of the motor. (Yes I did put the metal washer in the charge well after drilling the delay, and before adding the black powder.)



Video:
[The highway in the background is farther away that it looks, in some cases.]

Flightsketch data: https://flightsketch.com/flights/3620/

 

[waltr]

Nice flight.
I use 1gram BP in my LOC Goblin, 4" and about same length as your T-Loc.

I did sand the ridges on the nose so the fit is just tight enough that the BT will slowly slide off when lifting the rocket by the nose cone. Ground testing showed the nose ejecting with enough force the almost fully extend the cord.
The Goblin uses a 1/2" nylon strap and I 'braid' it for shock absorption. This has worked well on three flights.
The last flight the delay was way too long (Drilled 5 seconds off a 10 second delay but still was a 10 second delay). Goblin was coming down ballistic and ejection fired about 100 feet from the ground. Chute deployed with no zipper or other damage.

 

[Zbench]

Waltr,

Was that your goblin at the launch, the unfinished one? I saw that flight if so. Didn’t go very high was your saving grace.

 

[TheTank]

Finally flew this on July 2 2022 at NOTRA Launch. Flew on a G80-14NBT, with 1gram charge. It's a very tight nosecone fit. While it was a good flight and recovery. There was not enough "shock" to tear any of the masking tape bundles on the harness. I think I will lightly sand the ridges on the shoulder to get a slightly looser fit. It looks like a lot of charge went out the back of the motor. (Yes I did put the metal washer in the charge well after drilling the delay, and before adding the black powder.)

View attachment 525696

Video:
[The highway in the background is farther away that it looks, in some cases.]

Flightsketch data: https://flightsketch.com/flights/3620/

I sanded down the ridges as well on both of mine. It was very tight to start.

 

[waltr]

Waltr,

Was that your goblin at the launch, the unfinished one? I saw that flight if so. Didn’t go very high was your saving grace.

Sorry, I was not at that launch. So far have only flown it at our local field with PARA NAR section 520. Videos from on board camera are posted on the clubs Facebook. Last flight with too long a delay had a forward facing camera so good view of it hurling towards the ground.
With a G motor (G76 or G64) it goes 500-600 feet. I did my L1 cert with an H238 to about 900 feet with the Goblin.

 

[Scott_650]

Waltr,

Was that your goblin at the launch, the unfinished one? I saw that flight if so. Didn’t go very high was your saving grace.

Pete - that was Chris Feyerchak’s (the younger guy wearing a boonie hat who’s been working on his NARTREK Silver and Gold achievements) unpainted Goblin, he borrowed some sandpaper from me to take the ridges on the nose cone base down a bit.

John Bryan

 

[Zeta]

Fresh out of the paint shop....
View attachment 489570

wow unicorn gas power ...never thought of that !