Alpha III Motor Questions

[techrat]

I'll be (weather permitting) flying an Alpha III for the first time this upcoming weekend. I've flown plenty of larger rockets, but nothing this tiny since I was maybe 13yrs old. I'm starting with a B6-4 so I don't lose it on the first flight, but I've got plenty of other motors to try. One I am thinking of is the C6-7, because the long delay will give it plenty of time to fall before the 'chute pops, meaning it won't drift away. (two months ago at our group launch, we had a rocket go up, and it never landed. After the 'chute opened, it caught a thermal, and continued to go UP, so this is a real concern at this particular field).

Anyhow, any thoughts on motor choices? I got this Alpha III as part of a package deal of rocket stuff from a Craigslist ad, so I'm not concerned if I lose it, I just don't want to lose it right away.

 

[CalebJ]

I doubt it will fall much at all before deployment with a C6-7. The -5 and -7 are both recommended motors, so I'm assuming the apogee is estimated right in that range. It will definitely drift quite a bit if there's any wind at all.

 

[techrat]

I will be cutting a hole in the 'chute when I get home.... Interestingly, according to a chart on the internet, the max lift weight of a C6-5 is 113grams, but the max lift weight of a C6-7 is only 71grams. I'm assuming the longer delay charge means less room for propellant? Either way, the C6-7 rings as a "safer" choice than the C6-5, but somehow, I am already prepping to lose this bird as it's just too small. I prefer rockets I can still see when they are 500 feet up. 2" tube or bigger, 18" tall at least.

 

[neil_w]

The smaller lift off weight is because 7 second delay is too long for any rocket above that weight when powered by a C6.

Amount of propellant and thrust curves are the same regardless of delay.

 

[mh9162013]

How big will the spill hole in the parachute be?

Also, what kind of surface will your Alpha III be landing on?

 

[techrat]

How big will the spill hole in the parachute be?
Also, what kind of surface will your Alpha III be landing on?

I usually cut out the white center where it says "Estes", and that works for me.
It's a grassy soccer field with a large grassy area around it, and then trees. Lost a Big Bertha in the trees after trying to fly her on a Qjet D16. But that's life. I have since replaced BB with an "Olympus" from Hobby Lobby and I have to admit that I like this new rocket a lot better.

 

[Antares JS]

I will be cutting a hole in the 'chute when I get home.... Interestingly, according to a chart on the internet, the max lift weight of a C6-5 is 113grams, but the max lift weight of a C6-7 is only 71grams. I'm assuming the longer delay charge means less room for propellant?

The C6-5 and C6-7 contain the same amount of propellant, which is why they both have the "C6" designation. The C6-7 only contains two more seconds' worth of delay.

The reason the longer delay gives a lower maximum lift weight is because heavy rockets won't get going as fast as a lighter one, so once the boost cuts out they will reach apogee sooner, necessitating the shorter delay. A light rocket gets going much quicker and will reach apogee later, which allows a longer delay.

 

[mh9162013]

I usually cut out the white center where it says "Estes", and that works for me.
It's a grassy soccer field with a large grassy area around it, and then trees. Lost a Big Bertha in the trees after trying to fly her on a Qjet D16. But that's life. I have since replaced BB with an "Olympus" from Hobby Lobby and I have to admit that I like this new rocket a lot better.

Because you'll be landing in grass (and presumably using the stock parachute), you can probably cut out a spill hole that's larger than you currently have planned. This will increase the descent rate of your Alpha III and reduce the risk of loss due to drift.

Depending on how heavy your Alpha III is, it should be able to exceed 1,000 feet on a C engine. Unless you're in a big launch field and/or there's ZERO wind, you face a legitimate risk of losing the rocket with a C engine, whether you have a 3, 5 or 7 second delay.

 

[techrat]

Depending on how heavy your Alpha III is, it should be able to exceed 1,000 feet on a C engine.

Yikes! In that case, I'm going to curb my enthusiasm, and limit myself to A/B engines, at least until I decide I'm tired of that rocket and want to make it go bye-bye.

 

[neil_w]

Judge from your initial flights with the smaller engines. If it looks iffy, keep the C for another time.

You don’t need to make this decision in advance.

(That said, a C is going to send an Alpha III a long way.)

 

[techrat]

Well, if I take those plastic fins and give them a coating in lead, maybe I can keep those C flights under 1000 feet.

 

[mh9162013]

Well, if I take those plastic fins and give them a coating in lead, maybe I can keep those C flights under 1000 feet.

That sounds boring. Instead, give it an altimeter and strap on a small camera to add weight.

 

[Antares JS]

Well, if I take those plastic fins and give them a coating in lead, maybe I can keep those C flights under 1000 feet.

Adding weight to a rocket's tail end is not a good idea.

 

[samb]

My 2 cents (based on flying a lot of Alphas and seeing a lot more Alphas fly):

- Use an A8-3 for the first flight to see what the wind is doing 100+ feet up
- if necessary, adjust your spot on the field to maximize down range area
- have a party
- when you decide to kiss the sky with a C6 strongly recommend changing out the parachute for a 4-5 foot crepe paper or mylar streamer. They don't call 'um "C" ya later motors for nothin'.

 

[user 35280]

D20-8W Q-Jet (2-pak)

Better Data, Better Flights

flightsketch.com

 

[BEC]

Since Alphas and altimeters are both things I fly a lot, here are some thoughts based on flying Alpha IIIs with small altimeters (mostly FlightSketch Minis) stuffed up in the nose cone:

A stock Alpha III will do 500 ±50 feet on a B6. Typical B6-4 delays are actually more like 3s, and it’s a bit short. B6-6 also works well. Here’s a typical Estes B6-4 flight: https://flightsketch.com/flights/3647/ The Q-Jet B6-4W, if you get one of recent make, will take it a little higher. Here’s one on a streamer-equipped Alpha III, again, Estes B6-4: https://flightsketch.com/flights/3489/

On a C6, I have seen 1100 feet out of an Alpha III. The C6-7 is definitely the right choice rather than the -5 for maximum altitude. Like the B6-4, the C6-5 is a bit short for the model. Here’s a fairly recent C6-5 flight: https://flightsketch.com/flights/3423/. This one got nearly the full five seconds, so it was OK, not early, on its deployment. This is the same model - the one with a streamer.

On an A8, look for ~250 feet.

A 2x20 inch streamer rather than the ‘chute is not a bad idea if a soccer field is your landing surface. Also, you can reef the ‘chute with a bit of tape (wrap It around the shroud lines part way up their length to prevent the ‘chute from opening fully) as well as cut a spill hole to help it come down a little faster.

I’ve not flown an Alpha III on a Q-Jet C or D (I don’t think). A regular Alpha on a C12-8FJ is 1300 feet or so and 1250 on a C18-6W. I’ve not flown any Alphas on D16s or D20s. Something to try at Sod Blaster next month perhaps.

 

[DarenSavage]

I flew my Alpha III with Estes' Universal AstroCam and got some cool video footage. My test flight resulted in a very unusual SpaceX fin-first landing. I prefer using less powerful engines to limit the altitude so I can enjoy the flight. Flying the Alpha III on an A8-3 gives a flight that looks like the demo flight on the side of the box. Here's the video with slo-mo of my impossible test flight.

 

[techrat]

I have an idea about how to launch the Alpha III on a more powerful motor *AND* still get it back. Currently, there is a hole in the parachute. However, if I were to then make 4 cuts into the chute, starting from the hole in the center halfway towards the edge, I effectively turn the chute into a chute/streamer in that the hole is now huge , but, the remaining flappy plastic bits add drag on the way down.

Frankly, those bendy-plastic fins look like they can take quite a bit of impact regardless. I bet if I just tied a few bits of Xmas Ribbon to the shock cord, there's be enough drag to recover the rocket undamaged without a chute.

 

[lakeroadster]

I flew my Alpha III with Estes' Universal AstroCam and got some cool video footage. My test flight resulted in a very unusual SpaceX fin-first landing. I prefer using less powerful engines to limit the altitude so I can enjoy the flight. Flying the Alpha III on an A8-3 gives a flight that looks like the demo flight on the side of the box. Here's the video with slo-mo of my impossible test flight.

Spectacular....

 

[Back_at_it]

I have built and flown a lot of Alpha III's over the years and they are a great rocket. The B6-4 is a great motor for that rocket. The B6-6 is even better.

If you are dead set on flying it on a C motor then the C6-7 is the best option but I would seriously look at ditching the chute for a streamer. If you are landing on grass I would add a 1"x48" mylar or similar "shiny" streamer. It's going to be very difficult to track that rocket at the altitudes that a C motor delivers so the shiny streamer flickering in the sun will help a lot.

 

[jrap330]

Because you'll be landing in grass (and presumably using the stock parachute), you can probably cut out a spill hole that's larger than you currently have planned. This will increase the descent rate of your Alpha III and reduce the risk of loss due to drift.

Depending on how heavy your Alpha III is, it should be able to exceed 1,000 feet on a C engine. Unless you're in a big launch field and/or there's ZERO wind, you face a legitimate risk of losing the rocket with a C engine, whether you have a 3, 5 or 7 second delay.

If you really want to launch with C6, use a steamer or spill hole is not enough,, tie the lines also.

 

[jrap330]

Yikes! In that case, I'm going to curb my enthusiasm, and limit myself to A/B engines, at least until I decide I'm tired of that rocket and want to make it go bye-bye.

Doesn't Estes still list their estimated altitudes on the package? Small Rockets a B engine at max......unless Big Field, extra eyes and streamer.

 

[smstachwick]

My two cents here:

Estes makes 1/2A6 motors in this diameter. I’ve put them in a Phantom (a clear plastic Alpha III) and had successful flights to under 100 ft. If you want absolutely ZERO chance of losing it, that’s one way to ensure that.

A8-3, B4-4, B6-4, and C6-5 motors are all good choices, as are the equivalent A3-4, B4-4, B6-4, C12-6, and C18-6 Q-Jets from AeroTech.

The Q-Jet line also includes 18mm Ds, of which the D16-6 and D20-6 should do the job. Others have mentioned reefing the parachute’s shroud lines or swapping out the chute for a streamer, but here’s another option: the Alpha III is small enough to just blow the nose with nothing tied to the shock cord, although with nose-blow recovery you sacrifice visibility and take a greater risk of breaking things. Still, I’d prefer this to off-field loss of an airframe. As always, fly the field.

You may also want to consider a small Nomex fire blanket instead of Estes TP wadding. It’s more compact, which makes things easier with that short-ish tube.

 

[BEC]

Doesn't Estes still list their estimated altitudes on the package? Small Rockets a B engine at max......unless Big Field, extra eyes and streamer.

Yes they do, and most of the time they are quite optimistic. The Alpha III is one of the exceptions to that.

This discussion has made me pretty much decide to fly an Alpha III on a D16-8FJ at Sod Blaster IV if the winds are low enough. That will maximize altitude with currently available single use motors (D20 wastes more of its energy in drag). I actually have some SU D10-7Ws, which are full Ds, but I’m not THAT crazy, as that would be pushing 2000 feet.

I’ve flown models about that size on E6s but recovery was really dependent on luck and the largesse of the other contestants at NARAM-61 (we were flying E altitude) My model was not much bigger than an Alpha and used an Alpha VI nose cone — which is the same as the Alpha III nose cone save the color. These went to ~5000 feet.

 

[BABAR]

I flew my Alpha III with Estes' Universal AstroCam and got some cool video footage. My test flight resulted in a very unusual SpaceX fin-first landing. I prefer using less powerful engines to limit the altitude so I can enjoy the flight. Flying the Alpha III on an A8-3 gives a flight that looks like the demo flight on the side of the box. Here's the video with slo-mo of my impossible test flight.

That was a cool video, although at the end I I was going, “please don’t hit the car, please don’t hit the car, please don’t hit the car,please don’t hit the car…..”

did it remain upright on the landing?

 

[lakeroadster]

Yes they do, and most of the time they are quite optimistic. The Alpha III is one of the exceptions to that.

This discussion has made me pretty much decide to fly an Alpha III on a D16-8FJ at Sod Blaster IV if the winds are low enough. That will maximize altitude with currently available single use motors (D20 wastes more of its energy in drag). I actually have some SU D10-7Ws, which are full Ds, but I’m not THAT crazy, as that would be pushing 2000 feet.

I’ve flown models about that size on E6s but recovery was really dependent on luck and the largesse of the other contestants at NARAM-61 (we were flying E altitude) My model was not much bigger than an Alpha and used an Alpha VI nose cone — which is the same as the Alpha III nose cone save the color. These went to ~5000 feet.

Holy Schnikes! Are these being tracked just visually or are you using some sort of witchcraft to recover them?

My BT-55 upscale Ahpla was a challenge to recover, and it only flew to 1000 feet and tumble recovered.

​

 

[techrat]

All right, rabbit, you've convinced me. I'll search for Rocky in the city.... I like the ideas of an 18mm 1/2A and the idea of popping the nose without a chute as a recovery option although the RSO might have objections to that idea. But it seems the Alpha III (at 18 grams I believe) , is just too light for a C6 style engine if I ever want to see it again. I'm too old to go chasing it for miles. In July, I lost a Big Bertha by using a D16 composite motor, and Bertha is 4 times the size of an Alpha III.

That said, I prefer big fat rockets that I can still see when they are at 500+ feet, even with an E12 engine. Low and Slow is going to be my mantra. Of course, eventually I will tire of this little Alpha III, and stuff some 18mm composite motor in there to make it go away in a puff of smoke, but maybe that's for an October or November flight.

 

[smstachwick]

All right, rabbit, you've convinced me. I'll search for Rocky in the city.... I like the ideas of an 18mm 1/2A and the idea of popping the nose without a chute as a recovery option although the RSO might have objections to that idea.

It’s possible, but the method has been used from the earliest days of model rocketry and is compliant with the NAR Safety Code. Still, I’d say this is a most advisable option on C or D flights. 1/2A or A flights usually benefit from at least a streamer, the drift distance is small enough that the risk of breaking something isn’t as worth taking. For B flights, I think any safe thing you can get to come out of the tube and work on a reliable basis is fair game, even if that’s just the nose.

My guess is that the RSO’s decided permissibility on the nose-blow question would depend on how many other people are in the downrange recovery area during flight ops. It might be announced as a heads-up flight.

 

[BEC]

Holy Schnikes! Are these being tracked just visually or are you using some sort of witchcraft to recover them?

No, it's as I said, a combination of each of us finding each others' models and luck. We were flying at the International Aeromodeling Center, which is just about as good as a sod farm for recovery conditions. Shiny streamers and shiny bits on the models' exteriors helped a little. The E6 doesn't release much tracking smoke, and after a 5.6 second burn, the model is high enough where even if it did, that wouldn't help much.

I found my model after one of my two flights in the parking area behind were my shade canopy was. I don't recall who found my other one while searching for his own.

I believe Chad Ring was flying a Walston Retriever in his model, but I also remember hearing him grumbling about it either having failed or otherwise not helping. I don't think Jonathan Rains, who was the winner, with a flight to over 6000 feet, had any tracking device in his model(s).

All right, rabbit, you've convinced me. I'll search for Rocky in the city.... I like the ideas of an 18mm 1/2A and the idea of popping the nose without a chute as a recovery option although the RSO might have objections to that idea. But it seems the Alpha III (at 18 grams I believe) , is just too light for a C6 style engine if I ever want to see it again. I'm too old to go chasing it for miles. In July, I lost a Big Bertha by using a D16 composite motor, and Bertha is 4 times the size of an Alpha III.

You can always use a 13mm 1/2A in an adapter. The plastic Estes ones (https://estesrockets.com/product/002316-engine-adapters-mini-to-standard/) are light, fairly inexpensive with three pairs in the pack, and work very well. And yes, they are quite reusable.

A Big Bertha on a D16 goes to ~750 feet. For example: https://flightsketch.com/flights/3391/

 

[BABAR]

Nothing against nose blow recovery, however chutes and especially streamers have a dual function. Primary function is slowing down the rocket for safe recovery.

a second and often forgotten function is assistance in TRACKING the rocket in the sky and LOCATING the rocket on the ground/in bush/in tree. My understanding of streamers is that length to width ratios over 10:1 do NOT provide much if any additional slowing of the rocket (to get more effective streamer you need to go wider.)

HOWEVER, longer is definitely better for TRACKING and LOCATING purposes. So adding a long thin streamer (I like Mylar cuz it’s shiny) to your nose blow recovery won’t add much drift, but it WILL help you RECOVER your bird on the off chance that your rocket weathercocks of otherwise ends up ejecting or landing farther away than you expected.

Small streamers also pack easily in minimal space.

I find folding them in half, in half again, and repeating until a single roll will fit in the rocket makes Deployment faster and more reliable than rolling. Caveat, this is one case where (as opposed to chutes, which as an L-0 low and mid power rocketeer I like to pack just before launch) packing at home is easier, or at least in the car, as the folding technique on a long streamer is challenging in the field if there is even a minimal breeze (Can be a real PITB!)