Mars Lander Upscale Launch Report-Part 2 - Corrections
Tom Prestia
on to me that somehow got by my wife and I when we made up the instructions.
First off, in the parts pictures of the kit, I show 4 5-hole centering rings
for each kit. Wrong. There are only 3 in each kit and three are all that are
needed. That was an easy correction since if you read the instructions, you
would find you only needed three.
The second mistake is the photo of the gear housings, that was supposed to
show the correct placement of the housing cover. well, the bottom housing
shows the correct placement but the upper housing shows the housing cover on
incorrectly. If you follow the instructions, please refer to the lower housing
in the picture. The opening for the legs needs to be the short end of the
housing.
These are the only two mistakes that I have been made aware of. If anyone
finds more, please let me know and I'll post the corrections. Now to what I
learned on the flights Saturday.
For the 2X kits, I recommend 13 ozs of lead, separated into an 8 oz package
in the command module and 5 ozs in the nosecone. Well, my Level 2 flight had
the 8 ozs in the command module and 8 ozs in the nosecone. Since the flight
was completely stable, and that the H and I motors are half the weight of the
J180 I used, I now believe 8 ozs in the nosecone will be plenty to make the
Lander stable. There is plenty of room in the new nosecone for 8 ozs of BB's
or lead shot (I used BB's since they were cheaper).
For the 1.6X kits, I recommended 10 ozs of lead, 8 ozs in the command module
and 5 ozs in the nosecone. I flew my 1.6X Lander with only 8 ozs in the
command module and none in the nosecone. I believe if you only used 5-8 ozs in
the nosecone, the Landers will still be plenty stable. The new nosecone will
hold the weight but it may be pushing it to fit 8 ozs in the nosecone.
My 2X Lander weighed 5.5 lbs before I put the motor in. My 1.6X Lander
weighed 3 lbs before I put the motor in. So, the 2X kits should build out to
about 4.5 to 5 lbs and the 1.6X kits should build out to about 2.5 lbs. I
would be very surprised if the weights varied much from these.
According to WRASP, using a 5 lb 2X Mars Lander at 7.5" diameter,
H125 will go 825' and a 5 sec delay will be perfect, right at apogee;
I211 will go 1120' and a 6 sec delay will be perfect, just a hair after apogee.
According to WRASP, using a 3 lb 1.6X Mars Lander at 6" diameter,
F40 will go 275' and a 4 sec delay is just after apogee;
G64 will go 480' and a 4 sec delay is perfect, right at apogee.
One last change to the kits comes from Ed Miller. When he looked at my 2X
kit, he thought the heavy nosecone would snap back into the Lander at ejection.
His suggestion was to have the nosecone separate and come down on its own 18"
nylon chute. Thinking about this, I like it more and more, and it fixes the
one weak spot on the Lander - the balsa nosecone. If you have the nosecone
separate, the force of the 18" chute opening will be a lot less than the dual
chutes opening and trying to slow down a 3-5 lb rocket. This much lower stress
on the screweye holding the chute to the nosecone will probably mean this
screweye will never fail or pull out of the nosecone. By tying both chutes to
the shockcord, the chutes will never pull out of the nosecone and the Lander
will never have a chute failure due to a nosecone failure. I will be doing
this on my Landers from now on.
I hope this update helps your building of the Lander kits and also the flying
of them next year. If you think of any other improvements, please feel free
to post them here and drop them to me. I'll add them to the kits as I go.
Oh one last note. My 2X Lander hit very hard directly on one of its legs.
My new and improved legs survived without a scratch. Being able to open the
rear of the Lander was also a nice improvement, as the only thing the hard
landing did was pop the hinge off one of the supports. A very easy fix that
took two minutes.
Take care. I also have over 10 Landers of each size left to sell for this
year. I'll be making more next year but this is it for this year. Drop me
anote if you would like one. I really want to see or hear about some Lander
drag races next year!
Tom P.
Tango Papa Decals
Tom P.
Tango Papa Decals