The Semroc Mars Lander is close to the original. As Steve quoted from the instructions, the fiber parts including the rings, are the main difference. Anticipating the Quest D18, the thinner fiber did not look heavy enough for the extra stress. This and the larger chute adds about .8 oz to the weight. The CG-CP is about .40 for the original and .39 for the Semroc version. Both versions are marginal as far as stability is concerned. There is almost no stability if the angle of attack gets more than about 10 degrees. Wind and flights off vertical are disasterous. Adding about 1/2 oz of weight to the nose cone moves the CG forward and helps most that would be unstable.

Making sure the fins (landing gear) are tight and aligned, flying vertical in no or low wind, making sure the span is below 13.5", and not adding any more weight to the aft as possible all help make it more stable.

It is an impressive rocket when it is stable and when it is just sitting there. As I have said before, if I had realized how close it was to being unstable, we might have passed it. The Mars Lander is now a historic model from the early days of Estes from a very creative designer, Wayne Kellner. We have tried to capture his creation as close as possible.

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Carl McLawhorn
NAR#4717 L2
semroc.com

Carl, Thank you very much for the information. I am guessing that Estes orig. did not fly well, is that correct? Thanks David.....P.S thanks for the great service you provide.

The decals are slightly different also. You can get scans of the original Estes version online and use them on the Semroc kit.

Mine is about half done and on hold until football season is over. Hopefully I'll find some time and get motivated to finish it and several other half finished projects and then get started on the Saturn IB.

That is hard to say. Some have told me that they have over twenty perfect flights on the original. Some others said they had problems. Too bad we did not have forums in the 60's! The instant feedback is great for model rocket manufacturers. We can make changes and fix problems much more timely.

You are welcome, from all of us. We like that kind of feedback too.

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Carl McLawhorn
NAR#4717 L2
semroc.com

Carl

If there were Forums back then, at least they would be listening and make changes, action and not reaction, and Oh Boy do I know that...........

RD

I had two of them and they both flew nicely. Kids in my rocket clubs back then had hit'n'miss experiences, but I could tell it mainly came down to how well they were built and cared for. At NARAM this year, Carl pointed out the importance of the angle of the landing gear, and that probably is the key.

Now I have two complete Estes and two complete Semroc kits (and the very heavy Tango Papa kit), and eventually I will get around to building one of each.

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Roy
nar12605

My original always flew nicely.

Here's a picture of my cousins launching it circa 1972.

Attached Thumbnails

 

I love the old battery. What brand were those with the stripes? Wasn't it something like Mallory?

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Scott D. Hansen
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WOOSH NAR Section #558

Great photo Gus! It looks like your launch lug is on the outside of the BT100. Were the early Landers built like this? The instructions on JimZ's web site and the Semroc kit have the lug inside on the BT60. Yours is not the only classic lander photo I have seen with the launch lug on the out side. Thanks for posting the photo.

Mark

I just finished my Semroc Mars Lander about a month ago. (I still have my two original built Estes Mars Landers)

So far it has been launched on two OOP engines, an Estes C5-3 and an extremely rare Cox D8-3, both of which are much better choices than a B6-2 (don't bother) and a C6-3.
Both flights were very good....the C5-3 gets it off the pad in a hurry and the D8-3 was a considerably higher flight although at a slower speed.

The C6-3 is okay but what I would call "marginal" in thrust for something this draggy/heavy, thus the warning by Semroc to launch in next to zero wind.

Next two flights I'm going to kick it up a couple of notches by using my Aerotech RMS18
casing in White Lightning flavor.
If those go well I'll probably kick it up to a RMS18 D24-4T Blue Thunder reload.

I sure wish aerotech still made those 18mm "Baby " E reloads for the RMS18 casing.
Those would be great in the ML.

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When in doubt, WHACK the GAS and DITCH the brake !!!

Yes, there is such a thing as NORMAL, if you have to ask what is "NORMAL" , you probably aren't !
Failure may not be an OPTION, but it is ALWAYS a POSSIBILITY.
ALL systems are GO for MAYHEM, CHAOS, and HAVOC !