Jolly Logic 2

[aaronvanhorn]

How do you secure this device to the rocket? Is the altimeter worth the money?

 

[o1d_dude]

Most people attach their Jolly Logic devices to the shock cord.

 

[BEC]

...at least if they don't have a dedicated payload compartment in the model. In BT-50 (one inch) sized payload sections I just put a little padding below and above it without blocking the vents. In larger models I often will use a couple of centering rings and put in a BT-50 sized tube in the compartment and then do the same.

There is also the snap mount: https://www.jollylogic.com/products/snap-mount/

It really depends on the model.

 

[David Schwantz]

Love mine. Tether to shock cord. Just tie a loop to Alt and the around shock cord and back through itself.

 

[Zeus-cat]

Is it necessary? No. Is it cool? Yes.

Keep in mind that the data from a rocket motor combination will not change dramatically with repeated flights. An Alpha III on a B6-4 will have similar numbers flight after flight unless the weather or some other factor is dramatically different. That said, comparing the numbers from an A8-3, B6-4 and a C6-5 flight is very interesting. Also, you can compare the numbers on different rockets using the same motors. I enjoy using mine quite a bit.

And Jolly Logic altimeters are top quality; there is really nothing better (and one I won't mention that is a lot worse) for non-deployment altimeters.

 

[Walter Longburn]

My only regret is that I didn't get the altimeter 3 instead.

 

[aaronvanhorn]

My only regret is that I didn't get the altimeter 3 instead.

Expand on that

 

[Walter Longburn]

I would like to have my flights graphed on my phone and it can be used in some stuff other than rockets. Nothing major.

 

[Zeus-cat]

JL2 gives you one data point for 10 different parameters. JL3 provides X samples (10?) a second for the data it collects and sends it to your phone. I only have the JL2.

JL2 date from an H178DM flight
2,398 Apogee (feet)
374 Top Speed (mph)
1.17 Burn Time (sec)
18.0 Peak Accel
14.6 Avg. Accel
10.7 Coast to Apogee (sec)
-0.4 Apogee to Eject (sec)
2,381 Ejection Altitude (feet)
23 Descent Speed (mph)
81.7 Flight Duration (sec)

 

[aaronvanhorn]

JL2 gives you one data point for 10 different parameters. JL3 provides X samples (10?) a second for the data it collects and sends it to your phone. I only have the JL2.

JL2 date from an H178DM flight
2,398 Apogee (feet)
374 Top Speed (mph)
1.17 Burn Time (sec)
18.0 Peak Accel
14.6 Avg. Accel
10.7 Coast to Apogee (sec)
-0.4 Apogee to Eject (sec)
2,381 Ejection Altitude (feet)
23 Descent Speed (mph)
81.7 Flight Duration (sec)

Wait so if you wanted to know all of the above you would have to do multiple Flights?

 

[Walter Longburn]

Wait so if you wanted to know all of the above you would have to do multiple Flights?

No. Just 1 flight. It slowly scrolls through all the information.

 

[mikec]

A review here: https://www.rocketreviews.com/altimetertwo-200125233315.html

 

[jrap330]

I have to ask since it is on sale on ebay for less than $20. How accurate, durable or whatever parameter you want to mention is the Estes Altimeter. So far I am only launching model rockets and I can not justify to myself, $50 for Jolly Logic Alt I. I saw the interview with Jolly Logic owner on how Estes main concern is dollar value, everything needs to be built for $4.95 or less and sold for much more.

 

[neil_w]

My biggest problem with my Altimeter 3: forgetting to put it in, or forgetting to start it.

Love mine. Tether to shock cord. Just tie a loop to Alt and the around shock cord and back through itself.

I've been a bit curious about this... if the altimeter is in the parachute compartment and there are no vent holes, then presumably you won't get any reliable readings on the way up... but you also shouldn't be venting the parachute compartment. Or are very small altimeter vents not a concern with regard to ejection?

 

[Zeus-cat]

I have to ask since it is on sale on ebay for less than $20. How accurate, durable or whatever parameter you want to mention is the Estes Altimeter. So far I am only launching model rockets and I can not justify to myself, $50 for Jolly Logic Alt I. I saw the interview with Jolly Logic owner on how Estes main concern is dollar value, everything needs to be built for $4.95 or less and sold for much more.

Don't buy the Estes altimeter; there are a number of problems with it. If I knew where mine was I would send it to you for the cost of postage. And I would feel guilty for charging you that much. I have several Jolly Logic products and they are quality items; well worth the money in my opinion.

 

[jrap330]

Neil W- Mike Caplinger on RocketReviews, Jan 25, 2020 stated he does not put vent holes in his model rockets and appears the unit gives a reasonable accurate information. Per Mike- "Though the manual emphasizes the need for vent holes, I usually don't make any provisions for them and the values still seem reasonable. "

 

[David Schwantz]

As soon as it ejects you get the reading. I have used my JL2 to set club altitude records and they have seemed very close to the others in the same class. I do also vent all the compartments in the rocket. Av bay just gets more. Payload and booster section each get one.

 

[John Beans]

Looking back at the development of AltimeterTwo, it still kinda blows my mind that you can get a full rocket analysis from a little device with no help from a computer or phone. And it works for any rocket, not just those with payload bays. Hard to beat all that for convenience.

Also: the only Jolly Logic product you can't fully test any way other than a rocket flight.

This made me think back to standing in front of a display case at Seattle's Museum of Flight during a past NARCON, and noticing their timeline of how far model rocketry had come by displaying a modern digital altimeter.

The Estes altimeter.

And if you've been an altimeter fan over the last 10 years, you'll remember that this was a Chinese-engineered copy of AltimeterOne—same display format, packaging style, same one-button operation and menu logic, same exact random microcontroller (only ever used in an altimeter by the very first version of AltimeterOne and that Estes Altimeter).

So seeing that was kind of a bummer. At that point AltimeterTwo AND AltimeterThree were already out.

Sigh...

 

[neil_w]

Hey John, any status update on Altimeter 4? Is it still a planned product?

 

[mikec]

Neil W- Mike Caplinger on RocketReviews, Jan 25, 2020 stated he does not put vent holes in his model rockets and appears the unit gives a reasonable accurate information.

Obviously I wouldn't try NAR competition or anything without vent holes, but for sport flying it seems OK. I'm sure John can comment on how much filtering the barometric sensing has, how much error might be incurred, etc. I'm just looking for a ballpark altitude.

 

[neil_w]

I guess it should do ok got apogee. I was thinking of the fill flight profile from an Alt3. I have some rockets with ready-made payload compartments but not all.

 

[jrap330]

Thanks for replying John...

 

[BEC]

Every time I see that display at the MoF I have that same pang of "sheesh!", albeit probably not as strongly as John does.

On venting: it's really hard to seal a conventionally constructed model rocket up so tightly that it won't give you some kind of reading. In the case of an altimeter flying in with the recovery system you couldn't do it....or the nose cone wouldn't come off. That said, the data WILL lag the actual flight by some amount of time depending on how much leakage there is. For AltimeterTwo, it probably won't matter significantly. For AltimeterThree the time vs. altitude curve might get a little wonky depending on how snugly the nose cone fits and whether the ejection is early, on time or late with respect to the rest of the flight.

That said, I always vent whatever compartment the altimeter is riding in, whether its a dedicated payload section or not. The vents in the main body will generally be well above the wadding. I have never had an ejection failure that I felt was due to too much leakage out of vent holes. Ejection gases DO leak out the static ports, as discoloration around those holes clearly shows. This is one of four 1/8 inch holes in my Estes Silver Comet, which has flown five times so far.

.


Here is an AltimeterThree graph from a flight of a model where the A3 rode in with the parachute - it's a Big Bertha - in this case flown on a Q-Jet C12-4. This model has four 3/32 inch diameter holes in the body about 3 1/4 inches down from the top. Oddly, this is a model that doesn't really show any discoloration from ejection gases around the vent holes, even with a dozen and a half flights.

 

[billdz]

The FlightSketch Mini has a lot of nice features and was a great bargain at $18, but they have "temporarily" raised the price to $40, see https://flightsketch.com/store/catalog/flightsketch-mini_1/