Quest has just begun selling the Winged Shadow Systems "How High SP" altimeter . This is a self-contained peak reading (via a flashing LED) altimeter that weighs about 1/4 ounce and will fit in Centuri ST-8 and larger body tubes.

I acquired one of these devices and fitted it into a long-ago-built (1974 or 1975 - I'm not sure) but never-flown Astron Constellation and gave both the rocket and the altimeter a try with the first four flights last Thursday and three more today (Sunday).

The rocket weighs 1.4 ounces with the altimeter aboard but with no engine (or wadding) installed.

First of all, the Constellation, though I didn't do a very good job on it back then, flies straight and true, though after its seventh flight today (and second on a Quest engine) the engine hook came loose. Could be that the glued-on paper "engine holder strap" just let go. I've made a repair that involved wedging (and gluing) in a strip of 1/16 thick scrap balsa between the outboard side of the hook and the ID of the body. We'll see if that will work out. I'm tempted to split an EB-20 so it can slide past the upper end of the hook and glue it in...There's far too much residue in the top of the engine tube to try to put one in from the top now. When I build another from the Semroc xKit I will put in an engine block and also fix the engine hook a little more securely to the motor tube.

Anyway, all seven flights have been with the How High SP altimeter aboard, and here are the results:

Flight 1: Estes B6-4 489 feet
Flight 2: Estes C6-5 1077 feet
Flight 3: Estes A8-3 166 feet This one surprised me a bit that it was so low.
Flight 4: Estes B4-4 465 feet

Flight 5: Quest A6-4 212 feet
Flight 6: Estes B4-4 489 feet Chute deployed but didn't open, minimal damage.
Flight 7: Quest A6-4 217 feet (Motor hook loose after this flight)

All deployments were near apogee, with the QA6-4s being just a little past. Amazingly the 35 or so year old Estes parachute, as well as the 1/8 inch rubber shock cord are still good, too.

I'm pleased with the combination.

Thanks for the report. Good info there.

I take it the little Quest altimeter functioned well, even after a mishap.

I noted the A6 outperforming the A8. Interesting.

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The little mishap drove the altimeter into the base of the nose cone, bending the LED lead. I carefully straightened it and it was fine. I have now fitted a little piece of drinking straw so that the LED won't take that load should the same thing happen again.

I wonder if that A8-3 was a "dud" or something and will be getting more data - I'd have gotten another A8-3 flight off yesterday had the motor hook not come adrift.

Great information! I'll have to order at least one of these! The children will love it, and since (my wife says) I'm the biggest of the children, I get to use it first!
What a great, affordable, USEABLE piece of equipment Quest has offered us.
Allen

The Estes A8-3 is really an A3 motor while the Quest A6-4 is really an A5. The total impulse, of the A8-3, however, is a little more than the A6-4's and the A8-3 has a thrust duration about 50% longer than the A6-4. But, the maximum thrust of the A6-4 is about 20% higher.

Which leads me to the conclusion that ....uhhh .... I don't know.

-- Roger

Good one!

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I shouldn't have said that....about the shock cord anyway.....two flights later the shock cord broke at the mount and the payload section, altimeter and all, kinda drifted gently away, never to be seen again (at least so far - it's been about three weeks). The body/fins of course fell on the field and were recovered easily.

So one more departure from the traditional when I do another from one of the Semroc xKits - I'll go Kevlar/elastic instead of trifold paper/rubber for the shock cord, even though the latter is what's in the kit.

I've also gotten the bits from Semroc to fit a new payload section to the old Constellation (NB-50, BNC-50X, four inch piece of PST-50), but am not sure I'm going to ever fly it again.

But I did order two more of the altimeters and have fitted one of them to a modified Estes WalMart RTF Rascal. The Rascal has BT-50 tubing so just adding an NB-50 and about 3 inches of PST-50 and a screw eye turned it into a payloader for the altimeter. This one has two altimeter-recorded flights on it now.

I got three more flights on the RTF Rascal with the added payload section containing a How High SP altimeter (the one Quest is selling) tonight. So now I have five readings, similar to those for the Constellation....but lower.


On a cool morning - probably upper-40s:

Estes A8-3 - 122 feet
Estes B6-4 - 362 feet

On a warmer late afternoon - probably mid-60s:

Estes B6-4 - 355 feet
Estes C6-5 - 797 feet
Quest A6-4 - 111 feet (and a noticeably slow liftoff).

This setup weighs 1.9 ounces before motor and wadding, FWIW. That extra half ounce (plastic nose cone and fins) sure makes a difference. If I had a site big enough it would be interesting to try an Apogee D10-7W in this humble setup.....maybe about 1600 feet?

The delays seem to be about right for the B and C motors - it's just starting back down after apogee when the ejection occurs.

The conclusion you have is that te ltimeter is alwaysd 100% correct.

Bad conclusion.

I attempted to do an R&D project years ago, dozens of flight,s and used a small altimeter to determine the altitude. The flights ranged from 100 to 250 feet, according to the altimeter. I stood back about 150 feet each time, so I had a pretty good view of the flights. Some flights that it said were "low", looked visibly higher than that to me. Some that it said flew "high", looked visibly lower. I know that "by eye" you cannot really tell an altitude with any accuracy, but with the kind of side view I had for those altitude ranges, you CAN tell from flight to flight which flight went higher or lower than others. And the altimeter too often was not matching up with the obviously higher and obviously lower flights.

And then there was the one where it said the model flew 120-140 feet when it had tipped off terribly and flew horizontally never any higher than 60 feet.

Once I realized the altimeter results were unreliable, all those dozens of flights went for nothing. At least for that R&D project. The only R&D result I got was what I was not testing for, that I could not trust an altimeter.

Another thing from doing basic R&D. Repeat your tests. At least a minimum of 3 times per item or condition you are testing. With the same model in the same wind conditions on the same day, fly an A8-3, then A6-4, then repeat the cycle for 6 flights (three of each). If all three three A8 flights are lower than the A6 flights, and there was no unusual event diring the boost (like a tip-off), then OK, the altimeter is correct in indicating the A6's are making the model fly higher than on A8's.

I know, it is a hassle to get into it that much. But since the question was raised as to why, first you have to be sure that the data you are working with is reliable to begin with.

If it is all true, another possibility would be that simply the A6 is closer to delivering 2.5 N-sec than the A8 is.

- George Gassaway

That's what I was hoping to see: at least 3 flights with the same motor in the same rocket, just to see what kind of variation there was in the reported altitudes.

But at least his results report that the Constellation reached pretty close to the same altitude on its two flghts using Estes B4-4 motors, and that the RTF rocket reached similar altitudes on its two flights using Estes B6-4 motors. Those four flights imply that the Quest altimeter gives consistent results.

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John Thro, NAR #84553 SR
I was too old when I started! Now I'll *never* become a BAR!