Makers Corner

Just for reference, I've flown my Zephyr on Both G64-4 and G76-4 motors. Mine weighs 52 oz with no motor. I got a nice safe 538 ft. at the June 15 Acton launch on a G76-4.

And yes, I bought a DMS motor and an RMS casing. I guess I'll now get 1 or 2 F or G RMS motors to go with it.

Alright, I'll try the Zephyr with smaller motors first. I was hoping to save $$$ by not ordering the smaller engines but what fun is that?

I agree with Sam and Todd. Just going by what you mentioned about your rocketry experience so far it looks like you are looking to go from flying some A impulse Estes rockets when you were younger straight to an L1 cert attempt. You should get some experience with the lower impulse motors first. Have some fun. Play around with that JLCR you just bought. Try out some different sized parachutes. If you haven't already, use RockSim (or OpenRock if you would prefer) to play around with some simulations and see what the different motors can do for that Zephyr. Sam is absolutely right. You can get some decent lifting power just from some of those F and G motors. Jim also brings up another very good point. Keep that 38mm motor mount that came with the Zephyr kit, and then use adapters for whichever motor you want to fly it with; many more rocket motor options for you to try out and play around with. Remember to build the kit as strongly as possible (the kit instructions look pretty good) so that it can handle those higher impulse motors (and some rough landings!).

I agree that its a good idea to get some experience with F's and G's before jumping to HPR. There are some really good high thrust F's that will send an L1 rocket up 200-300 ft. And there are of course G's that can easily lift a light weight 4" rocket. I have flown my Estes PSII Nike Smoke on motors from F to H. You can even fly it on a small I if you beef it up a bit.

I'm interpreting that you wrote that you bought a DMS motor to go in the casing. To be clear, a DMS (Disposable Motor System) motor does not use an RMS casing - it comes with all necessary parts that you assemble and use once. You'll need the RMS/DMS delay drilling tool do bring the 14s delay down to ~5s.

You also wrote that you're going straight from Estes 'A' as a kid, to an L1 first flight getting back into the hobby. Why not build and fly on some F or Gs first at Acton, or buy an Estes Pro Series and fly on one of their 29mm black powder motors? Even Wernher Von Braun got some pre-flights in before going "all-up" on the Saturn V. :-)

I usually either buy them in person, or if I pay hazmat I am usually spending enough to make the shipping reasonable (often >$1000). There are a few L1 motors that qualify for normal ground shipping which you might also want to consider. Also Wildman CT isn't that far, and he can arrange pickup at his house.

Thank you both Jim & Sam. I'm in Hingham but already ordered a RMS-38/120 casing with closures and an Aerotech 38mm HP SU DMS Motor - H100W-14A to go in it. I need to decide what I want to do for future launches before investing in more motors. So far I just have my first rocket kit (Apogee Zephyr) coming and the one H motor kit w casing for the Level 1 certification. I'm counting on one certification flight to work the first time this September at Amesbury. I built & launched a few Estes A rockets as a kid and am just getting back into it. Any recommendations for what to build and/or launch after the Zephyr would be most welcomed. - Kevin

Where are you? I am planning to go to METRA this weekend and URRG next week, soI could potentially pick up an order for you. I won’t be in Acton, but we could arrange a pick up if you are close to Brookline or Cape Cod.

Sam

Buying at the field is a great option when available. Unfortunately, we usually only have an HPR vendor there once or twice a year.

You could also go in with others to share the ~$50 HAZMAT shipping fee. There's often several others looking to share that cost.

I love Balsa Machining as a vendor. Apogee too, though I agree the latter is an expensive options for motors. BuyRocketMotors.com also offers good discounts.

You'll also need to decide whether to buy a reloadable motor and case, or use a single-use (DMS) motor. If you've never assembled a motor before, then DMS is a good option. Or at least go with a Cesaroni case and motor since those are much easier to assemble.

Even though you have a 38mm MMT, you'll save a little bit in motor cost if you go with a 29mm motor with an adapter. Make sure your motor retention will retain both the motor and the adapter. I strongly recommend against friction fit for HPR.

Our next launch is in ~10 days in Acton which can't allow HPR. So that would be a good time for a first flight on a G motor. While the 29mm Gs are more common, I do love the 38mm 1 grain motors like the AT G67R

Apogee is pricey. Believe it or not try Balsa Machining Services. They offer a decent selection of motors and at a reasonable price, assuming they have stock on the motor(s) you want.

Wow! Motors are expensive. $80 shipping! I ordered straight from Apogee. What's my best option for purchasing motors? - Kevin

Thank you to all who replied for your advice!

I learned a lot. Thank you for running the Zepher through Rocksim. I just ordered myself a JLCR.

Kevin Scannell

Since there are always unknowns and since you are flying a well-designed kit, I suggest you fly it on a small H as its first flight.

I don't think there is much to be gained by flying it on G first.

Jim

For my L1 certification, I also used a 4" diameter rocket, with a 38mm MMT and an optional payload section (BSD Horizon - OOP). After sim'ing in Rocksim, I tested the rocket first without the payload section on a high impulse 'F' motor, and then with the payload section on a G80. Both in Acton, both 29mm motors with an adapter. Both flights with a JLCR, and both recovered without harm.

After building confidence using those motors, I cert'd with an H238 (I think) at Amesbury.

Looking at the Rocksim data for your rocket, I would fly first with an F52-5T (optimal delay is 4 seconds - 420' at apogee), and then something like a G77 (optimal delay is ~5 seconds - 690' at apogee). Both would result in lower (but not too low) altitudes. But the G61s that you bought would also work, with an altitude at deployment of 775' (optimal delay 5.25 secs), which is recoverable at Acton with the added insurance of something like a JLCR.

To answer your question, you won't need more motors than what you have to verify your build and finally cert. Fly it a couple of times on the Gs, and then cert with your H.

Hi Kevin,

That's a nice looking rocket for your L1 attempt. Even though two G impulse class motors will in fact add up to an H, by the L1 certification rules you will need at least one(1) H motor, even if using a cluster powered rocket. You wouldn't want to cluster anyway, as it would add complication at a time when you really don't need it; unless you really want the challenge of it. Unless something has changed (and to my knowledge), you can only buy one motor for your certification attempt from a dealer (they will be asking for your proof of certification). Good luck!

NAR #74527 L1

Dear Forum,

I'm a new member buying my first motors for an Aapogee Zephyr rocket kit intending to use them for a Level 1 Certification attempt. My question is: How many motors of what sizes should I buy for a Level 1 Certification attempt? I've ordered (2) Apogee G61W's and one Apogee H123W (for the certification attempt). Your recommendations?

Kevin Scannell