Quantcast

Estes Altitrak???????

The Rocketry Forum

Help Support The Rocketry Forum:

El Cheapo

Well-Known Member
Joined
Jan 20, 2009
Messages
1,659
Reaction score
2
Has anyone ever used one? I have one in the bag that I won in a raffle and am curious if it's even worth the effort to cut the bag open.
 

Peartree

Cyborg Rocketeer
Staff member
Administrator
Global Mod
Joined
Jan 6, 2009
Messages
5,205
Reaction score
710
Location
Alliance, Ohio
I have one and (almost) never use it. Either we don't have enough people, don't have enough time, or simply don't care. I have it in my range box "just in case" but then you need a calculator to go with it.
 

Queeg500

Well-Known Member
Joined
Jan 20, 2009
Messages
204
Reaction score
0
Our club uses it because we can't afford the $65 altimiter from Transolve. We try to use it at every flight meet. It's a good intro to trig.
 

dwmzmm

Well-Known Member
Joined
Jan 18, 2009
Messages
1,932
Reaction score
5
The Altitrak should be a gem; if you don't want it, just send it to me!:D
 

El Cheapo

Well-Known Member
Joined
Jan 20, 2009
Messages
1,659
Reaction score
2
I'll probably donate it back to the club for a raffle this weekend. I generally have my hands full with a 6 & 7 year old at the club launches.
 

Queeg500

Well-Known Member
Joined
Jan 20, 2009
Messages
204
Reaction score
0
this topic begs the question - do Estes rockets actually reach the altitude maximum listed on the kit package? I think what we are discovering is that they don't because we have flown a Blue Ninja on a D12-5 about eight times in a year, at least, and got 250-270 feet at 60 deg. F dry air. The 2007 catalog says max altitude for the Blue Ninja is 700ft. and lists C11-3 and D12-3 as the only engine options.
 

El Cheapo

Well-Known Member
Joined
Jan 20, 2009
Messages
1,659
Reaction score
2
Honestly, for what I see them going for on Ebay, I might just Auction it and spend the another $25-$30 for that little altimiter thingy quest has.
 

CharlaineC

Well-Known Member
Joined
Jan 19, 2009
Messages
1,099
Reaction score
4
I have two altitracks and love them keep them in the range box and use them to when i have a few people extra. or with the scouts
 

cjl

Well-Known Member
Joined
Jan 18, 2009
Messages
12,549
Reaction score
5
this topic begs the question - do Estes rockets actually reach the altitude maximum listed on the kit package? I think what we are discovering is that they don't because we have flown a Blue Ninja on a D12-5 about eight times in a year, at least, and got 250-270 feet at 60 deg. F dry air. The 2007 catalog says max altitude for the Blue Ninja is 700ft. and lists C11-3 and D12-3 as the only engine options.
Honestly, you should be getting quite a bit higher than that. It may not hit 700, but a D12 is enough power to get a blue ninja sized rocket to at least 500, despite the plastic fin can.
 

Micromeister

Micro Craftman/ClusterNut
TRF Lifetime Supporter
TRF Supporter
Joined
Jan 19, 2009
Messages
15,074
Reaction score
45
Location
Washington DC
I have two altitracks and love them keep them in the range box and use them to when i have a few people extra. or with the scouts

We've done the same thing using 3 station tracking using 3 of the much older altiscopes back in the 80's. Once the Scouts learned how to hold them consistantly they were closing tracks within 7points. They are fun little gidgets for sport flying with a group, particularly if your group doesn't have a set of theodolites.

AltiScope Tracking stations-a-sm_1 of 3 sets_04-05-86.jpg
 

Queeg500

Well-Known Member
Joined
Jan 20, 2009
Messages
204
Reaction score
0
Honestly, you should be getting quite a bit higher than that. It may not hit 700, but a D12 is enough power to get a blue ninja sized rocket to at least 500, despite the plastic fin can.
ok, we are using the small field calculation: base = 250 ft, times tangent = altitude, then divide the altitude by 2. With this last Ninja flight the angle was 65 deg. --> 2.14 tangent times 250ft. = 535ft. Dividing this by 2 is 267.5 feet.
 

cjl

Well-Known Member
Joined
Jan 18, 2009
Messages
12,549
Reaction score
5
ok, we are using the small field calculation: base = 250 ft, times tangent = altitude, then divide the altitude by 2. With this last Ninja flight the angle was 65 deg. --> 2.14 tangent times 250ft. = 535ft. Dividing this by 2 is 267.5 feet.
Why are you dividing by 2? Not only do I not see any need to mathematically, 535 feet is in the range of reasonable altitude for that rocket on that motor.
 

Queeg500

Well-Known Member
Joined
Jan 20, 2009
Messages
204
Reaction score
0
I'm dividing by two because the instructions on the back of the package say to do exactly that: "Note: For low altitude rockets, pace off 250ft. and divide hight by 2. For high altitude rockets, pace off 1,000 ft. and multiply height by 2".
 

cjl

Well-Known Member
Joined
Jan 18, 2009
Messages
12,549
Reaction score
5
If you're calculating directly based on the angle, there is no need to divide by two. If you are using the height values read directly off of the device, you would have to divide by two because they are precalculated assuming a 500 foot baseline.
 

Queeg500

Well-Known Member
Joined
Jan 20, 2009
Messages
204
Reaction score
0
Thanks CJL. I took the instructions to mean halve the height from the trig caluclation not the Altitrack meters reading.
 

cjl

Well-Known Member
Joined
Jan 18, 2009
Messages
12,549
Reaction score
5
That definitely explains the odd altitude readings :)
 

bobkrech

Well-Known Member
Joined
Jan 20, 2009
Messages
8,353
Reaction score
33
What the instructions are trying to do is to make the angle about 45 degrees to minimize the effect of elevation angle measurement errors. If you are off by +/- 1 degree in your elevation angle measurement at 45 degrees, your calculated altitude will be in error by only 3.5%, and within 4% for elevation angles between 30 degrees and 60%, and within 5% from angles of 22 degrees to 68%. See the attached plot.

If your flying to 250', then the base is ideally 250'. If your flying to 500', then the base is ideally 500'. If your flying to 1000', then the base is ideally 1000'. Etc.

The altitude for an 65 degree elevation angle with a 250' baseline is 250' x tangent (65) = 250' x 2.1445 = 536' +/- 4.56% = 536 ' +/- 24.4' error for each degree of elevation angle error.

With a 500' baseline and the same altitude the angle becomes arctan(536/500) = 47 degrees and the measurement error would be reduced to 3.5% or +/-18.4' per degree of elevation error. For fun flying it not that important, but for competition it is.

Bob

altitude error vs angle.JPG
 
Top