New Member! 1st time w a MP Rocket

[caveeagle]

Hello folks! New to the forum, looking for some input on my first step into a Mid Power Rocket build.

Background: I built and flow tons of Estes rockets as a kid, until I got into flying RC models. I started back into rocketry as my boys got old enough. We ended up in a cub scout group that had an annual 'rocket day', so I have had another 10 years helping kids build and fly smaller rockets a couple times a year. Because we were located in HOT SUNNY Florida, I built a nice custom PVC triple launcher, that gets the rockets a couple feet up off the ground. (got tired of bending over all the time). The triple pads worked out great, because in a pack of 50+ cub scouts, there never seemed to be enough launchers for all the kids.

Anyway... We have moved up to the Chicago area, my 15yr old son is now in a Boy Scout troop (older than Cubs), and they have a "rocket" themed campout comming up. My son had had some trouble adjusting to the move, and I was trying to get him motivated for this event. We went off to the local Hobby Lobby, where I told him he could get whatever rocket he wanted!! (man would I have loved that as a kid!)

We picked up a Pro SeriesII 'Ventris' rocket. I could see that it was a big sturdy rocket, and the "Pro SeriesII" label looked real impressive. How bad could it be? Right? Well, its a nice kit. Much better than ANY rocket kit I have built before. I was determined to let the kid build this one!

My qustions are around the engine selection and setting up my launch system to handle this beast.

I have been looking at the Aerotech single use motors. It sounds like the single use motors can be ignited with a standars 'Low Power' ignitor system. Right? I think my current launch controller is powered by 4D cells. (6v). So hopefully that will work.

It sounds like the Pro-SeriesII rockets need a 1/4"x60" launch rod?? I know my current pad is large enough to handle this. Just wondering Where I can find a 1/4"x60" rod. estees does not seem to sell just the rod, and I really don't want to buy another pad. More about space that the $$. (too much stuff in the garage already). I know I can get 1/4" rod at the hardware store. Just not sure about the 60" length.

Any input would be appreciated. I hope I can pull this together for my kids scout event. He seems to be looking fwd to this.

Thanks....

mark

 

[GregGleason]

Welcome!

A 1/4 inch rod you can usually get at a home center (Home Depot, Lowes, etc). If you find one, make sure you roll it on a granite counter to make sure that it is true and not bent.

If one is not nearby, you can order one from McMasterCarr.

BTW, my older boys are scouts. My oldest son and I built a Ventris that we flew last month for the first time at our club launch.

Here is a liftoff pic of it going on a G64-7W:



Greg

 

[therocketfarmer]

I got my last 1/4 rod at Menard, was something like 12.00. The pro motors require the use of pro igniters or similar, they will light off of a regular launch controler as we have done that in the past, make sure you hold the launch button untill you see it fire. other than that your on the right track, pretty soon you will be purchasing Wildman, Binder, kits etc!!! and reloadable motor caseings bla bla bla... LOL but welcome and enjoy. there is a High Powered launch not to far from the Chicago area on the first weekend of november. Midwest Power.. https://midwestpower.org/

 

[DizWolf]

Estes "sonic" ignitors will light with 6v. Aerotech ignitors take 12 volts.

Unlike BP motors, make sure ignitors for composite motors are installed all the way to the top of the motor.

I've launched one pound rockets on F motors off a three foot rod. As long as it's moving fast enough at the end of the rod your good. Got a motor in mind?

 

[samb]

Welcome back. Good choice on the Ventris (any of the Estes PSII's would be a good choice IMO). Hobby Lobby did carry the Estes single use engines (re-branded Aerotech) and the PSII igniters that will work on a 6 volt launch system. Did you already pick them up when you purchased the Ventris ? I know that HL is moving the PSII rocket line to the clearance aisle so you may be able to find some engines there, not sure about the igniters. Aerotech motors will also work but Copperhead and FirstFire igniters specify 12 volt systems for reliable operation.

I'm a big proponent of flying with a club. You get to see a bunch of great rockets and they have all the equipment you'll need to launch yours. Find one near you:

https://www.nar.org/NARseclist.php

www.tripoli.org

 

[caveeagle]

Estes "sonic" ignitors will light with 6v. Aerotech ignitors take 12 volts.

I thought the Aerotech site indicated their 1-use motors could be fired from a standard launcher?? I will double check.

I've launched one pound rockets on F motors off a three foot rod. As long as it's moving fast enough at the end of the rod your good. Got a motor in mind?

I need to check on the field situation at our campout.

The Ventris kit suggest: F26-6FJ, F50-6T, G40-7W, G80-7T

I assume I will be looking for the most 'conservative' motor for the first couple of flights.

Any suggestions?

 

[JPVegh]

A Standard controller will light the new igniters but you also need to think about a safe stand off distance for mid power motors. You need a controller with thirty feet of wire to be NAR compliant.

 

[GregGleason]

... The Ventris kit suggest: F26-6FJ, F50-6T, G40-7W, G80-7T

I assume I will be looking for the most 'conservative' motor for the first couple of flights.

Any suggestions?

I would go with the F impulse selections, since a G impulse will almost double the altitude. The F50 is a "T", which is Blue Thunder propellant, which is the easiest to light of the propellant options. That will help your ignition with your launch controller.

Or ...

Before picking the motor (and only do this if you have enough time), is figure out the what the weight of the rocket will be at the pad with everything except the motor. Once you know that weight, you can use simulation programs like OpenRocket to calculate your altitude with other AeroTech motors.

Also, you may have to plan your motor purchase in advance if they are not available at your LHS (local hobby shop) and you need to order by mail.

Greg

 

[caveeagle]

A Standard controller will light the new igniters but you also need to think about a safe stand off distance for mid power motors. You need a controller with thirty feet of wire to be NAR compliant.

I should be good on the distance. I am using a custom built launch controler that I built for our 3-pad launcher. I will post some pics at some point. It has a safety key, and 'arm' button, and three separate "launch" buttons. our cub scouts had a lot of fun with it!!!

 

[Rex R]

I would suggest an F50-6t, goes about 200' higher than the F26, but gets the rocket off the pad with less weathercocking. both motors will deploy just over the top. while it is tempting to over build(using epoxy on everything)...it isn't needed. about the only things I would suggest epoxy for; tube coupler, the forward centering ring, the motor retainer, and glueing the transition to the 'payload' tube. the included 'Tri-fold' shock cord mount works well (white/yellow glue).
Rex

 

[blueapplepaste]

Might also consider an aerotech 24/40 reloadable motor. I recently also got into MPR with somewhat similar story as yours and the price of the 24mm reloadables vs 29mm single uses made it worthwhile IMO. Plenty of nice E and F motors in the 24mm size to get her nice and high. Just food for thought.

 

[samb]

I thought the Aerotech site indicated their 1-use motors could be fired from a standard launcher?? I will double check.
...

The FAQ on the Aerotech site says exactly that (https://www.aerotech-rocketry.com/faq.aspx):

"How are AeroTech model rocket motors ignited?
AeroTech single use model rocket motors are ignited with a 2-wire initiator similar to that used in black powder model rocket motors. They can be ignited using the same electrical launch controllers used for black powder model rocket motors too. AeroTech reloadable model rocket motors are ignited using the AeroTech “Copperhead” initiator which requires a special clip and a 12 volt launch system. In either case the initiator must be placed at the top of the propellant core space, rather than just inside the nozzle as with black powder model rocket motors."

I've never tried this myself.

I'd be inclined to go with the F26 for your first flight. Besides a higher thrust motor liked the F50, you can compensate for wind by angling the launch rod with the wind so the that the weathercocking brings the flight path back towards vertical. The Blue Thunders do tend to be easier to ignite

 

[Coop]

Given your experience with MPR and all (particularly with scouts around), I'd give the opposite advice as Samb, above: go with the F-50 (of the motors you listed) and keep the launch angle at zero. You've never flown this, don't know if it'll weathercock, and if it DOES, how much at any given wind speed, and what angle is best to compensate for it. That --to me-- sounds like the safest plan...


Welcome, and have fun!


Later!

--Coop

 

[Jarhead]

PM sent

 

[samb]

Ok, 2 to 1 for the F50 !

I can't disagree with anything Coop said. Any speculation about weather cocking is just that and going with a zero launch angle is always a safe bet. Good luck an please report back after the scout launch.

 

[Rex R]

ayup the ventris will weathercock .
rex

 

[jtk1]

+1 plenty of good aerotech 24mm reloads and also Single Use 24mm motors such as the E-20, and the F-32, one of my favorites!

 

[caveeagle]

Please educate me on using a 24mm motor in a rocket designt for a 29mm motor. I deffinately want to be a little conservative for a 1st launch. But I also thouht it would be best to stay close to the recommended motor sizes until I get a better grasp of MPR.

Also keep in mind I am trying really hard to let my 15yr old build this rocket without too much meddling by me. He has made it clear that he does not want me to 'take over' this build. (I 'may' have been a little guilty of this in the past)

 

[GregGleason]

You would need a 24mm/29mm adapter.

Aeropack is one source that makes them. https://aeropack.net/motoradapters.asp

Greg

 

[caveeagle]

My kid pretty much has this rocket together. The kit came with a 90" long elastic shock cord. Is that long of a cord really advisable? I did not see anything in the instructions about cutting it to length.

I an planning to try and find the F50-6T motors locally.

I found a good 6' section of steel 1/4" rod at lowes. I should be able to adapt that to our launcher without too much hassle.

 

[GregGleason]

You can use all of the cord. Just tie the chute to the band about 1/3rd of distance from the coupler attach point (upper airframe) to bottom airframe. Some use a rule of thumb that the length of the recovery harness needs to be at least 3 times the length of the rocket.

I will say that over time, the heat exposure from ejection will degrade the elastic and at some point it can fail. Many will substitute braided Kevlar because it is heat resistant. The downside of Kevlar is it doesn't stretch, so the rocket is at risk of a zipper if it has a high-energy deployment.

Greg

 

[qquake2k]

My kid pretty much has this rocket together. The kit came with a 90" long elastic shock cord. Is that long of a cord really advisable? I did not see anything in the instructions about cutting it to length.

I an planning to try and find the F50-6T motors locally.

I found a good 6' section of steel 1/4" rod at lowes. I should be able to adapt that to our launcher without too much hassle.

I think 90" sounds kind of short, personally. But it's probably enough. I wouldn't shorten it, though.

 

[caveeagle]

The estes Pro Series II Launcher (recommended) has a 60" launch rod. So, that was my baseline to work from. Anyone else think I need more than 60" for this rocket? Its kind of a long (1 piece) rod to carry around in my car.

On another topic, ..... back in the day, I used to use dope, or sanding sealer to get my rockets and planes ready for paint. I didn't see anything appropriate on my last trip to the hobby store. What are you guys using? Anything??

 

[Rex R]

90(or more) inches of shock cord, as mentioned do not attach the chute directly to the nose section. 60" launch rod works nicely. high build primer will work, I've been known to use spot & glazing putty on plywood fins(slather on, sand, paint).
Rex

 

[caveeagle]

Would the Econojet F42-8T be a decent alternative to the F50-6T motor?

I really like the idea of getting a 24mm adapter and trying out the 24mm reloadable option. I am just not sure if we will be active enough to justify this. We also play around with RC aircraft, and am not totally sure if we will have a good area to fly/launch nearby.

****
I just found "Al's Hobbys" not to far from me in the Chicagoland area. They have a couple of F50-6T motors on hold for me!! I was considering Picking up a G40 or G80 as a possible 3rd launch if the first two go well. Should I hold off on the heavy stuff? Or go for it?

 

[Initiator001]

Would the Econojet F42-8T be a decent alternative to the F50-6T motor?

No. The delay is too long.

Use a F42-4T motor.

I have flown my Ventris with both F50-6T and F25-6W single-use motors. Both were great flights and reached altitudes around 1200 feet as I recall the display on the altimeter.

 

[caveeagle]

So the F25 and the F50 both reached a similar altitude? I guess I have some learning to do on rocket engine types.

 

[Rex R]

more like propellant types, the F26 has a slower burning propellant, so the rocket takes longer to reach apogee(but it leaves a cool black smoke trail ).
Rex

 

[caveeagle]

Cool. Thanks for the info. I am trying to line up the best engine type for an initial launch, but still get a nice dramatic show. Not trying to scare small children (of course), but something a little more dramatic than out typical A/B/C motors that we are used to.

Not really sure if we will have time and logistics for more than a couple launches. This is the first time for us flying with this group and location. I was planning to pick up two F50 motors and then maybe the G40-*W motor to use if the conditions are favorable.

Will the aforementioned rocket simulator (OpenRocket) give us a good idea of altitude and timing for a given motor?

 

[qquake2k]

Yes, Open Rocket will give you flight sims for the different motors. You can also use Thrustcurve. One of my favorite propellant types is Blackjack/Fastjack. Lots of black smoke. White Lightning is good too, but with white smoke.