Loc IV redesign

I wanted something bigger so I took a Loc IV and put an extension on it using a payload bay. That added 11 inches. I also redesigned the fins just because and besides, it helps get the margin down closer to '2' (whether or not that makes a difference?). Does anyone have anything to offer? I want to stay with the 29mm, G80-7T if possible. I am not certified so can't go bigger right now anyway. See attached Rocksim. I am still learning that program so there are probably some mistakes there.

gary7 said:

I wanted something bigger so I took a Loc IV and put an extension on it using a payload bay. That added 11 inches. I also redesigned the fins just because and besides, it helps get the margin down closer to '2' (whether or not that makes a difference?). Does anyone have anything to offer? I want to stay with the 29mm, G80-7T if possible. I am not certified so can't go bigger right now anyway. See attached Rocksim. I am still learning that program so there are probably some mistakes there.

Click to expand...

Does anyone have anything to offer?

Well, maybe some hints on how to attach a Rocksim file....

I certified Level 1 on a Loc IV back in '93 with a Vulcan Smokey Sam H100......... if you can imagine that.
It went nearly out of sight and I had to walk a 1/2 mile...being an apogee deployment.
It has countless flights, an old reliable.

Still flies but had two major repairs, and numerous reapplication of fins, which were notorius for breaking off..(the original kit had surface mounted fins instead of thru the wall) and as they stick out below the airframe they broke off alot.

I love the kit otherwise, loads of fun.

My attempt to attach the file didn't work, obviously. I have now attempted a zipped file.

View attachment Gary's_Loc_PK-48_Loc_IV_Extension_fin-c.zip

gary7 said:

I wanted something bigger so I took a Loc IV and put an extension on it using a payload bay. That added 11 inches. I also redesigned the fins just because and besides, it helps get the margin down closer to '2' (whether or not that makes a difference?). Does anyone have anything to offer? I want to stay with the 29mm, G80-7T if possible. I am not certified so can't go bigger right now anyway. See attached Rocksim. I am still learning that program so there are probably some mistakes there.

Click to expand...

A 7-second delay is too long for a LOC IV flying on a G80 with the payload bay. I've flown my LOC IV several times on G motors, and I always use a 4-second delay. Four seconds is a little early without the payload bay, but should be just about right with it. With the payload bay and a RR G80-4 my LOC IV weighed 1.4 Kg. My PerfectFlite altimeter measured an altitude of 608 feet.

Dave

The shortest delay on the new (137 N-s) G80T is 7 sec. The new G80 T is offered in 7, 10 and 13 second delays as compared to 4, 7, and 10 for the old version. Aerotech made mention of using a 3 second longer delay for this motor in your rocket as compared to the previous version due to the greater total impulse.

1.4 kg is probably still too heavy for the new G80-7T though.

I've never flown the new Aerotech G80, so I was basing my opinions on the old Aerotech G80 and the Road Runner G80. Based on the Rocksim results it looks like the 10% extra impulse makes a significant difference in altitude. Your LOC IV weighs about 250 grams more than mine. The simulation shows that your rocket will go 501 feet on the Road Runner G80. However, on the new Aerotech G80 it sims to 744 feet.

The time to apogee is 7.25 seconds, and the burn time is 1.7 seconds, so the optimal delay would be 5.55 seconds. However, the test data for the Aerotech G80-7 shows an average measured delay of 5.9 seconds, which is only 0.45 seconds longer than optimal. So it looks like the new Aerotech G80-7 is very close to optimal for your LOC IV.

Dave

Once again,I am new to all this so please be patient: I am working on this redesigned Loc IV with a payload bay and fins of a different design. My question: is there enough room between the motor tube and the payload bay or am I cramming too much in there, ie., parachute, hardware and fire blanket? Any other comments welcomed! Thank you.

View attachment Gary's_Loc_IV Redesign Final.zip

Unless you plan on using a long Kosdon 1"motor; it's not going to clear the rail with a 24mm mount in it. Go with a 38mm, it will open up allot more choices.
Shorten the stuffer tube/ Motor Mount to 18". That should allow enough room depending on how long of a cord you choose.



JD

JDcluster said:

it's not going to clear the rail with a 24mm mount in it. Go with a 38mm

JD

Click to expand...

Thank you, JD, Ill make the tube length change. But, as my Rocksim plan shows, I was planning to use a 29mm MMT. That will take a G80 with an option to go with H220 or H250 (both 29mm) if/when I decide to attempt my L1 certification. All three choices work, at least in Rocksim. My thinking was that if I ever want to go bigger, I'll get a bigger rocket.

Nice re-design..The reason you couldn't attach the RS file in it's native form was all the simulations 'bloating' the file size..I ran a couple of sims on it and the 7 second delay does look to be a tad long..You could adjust the delay grain down to 6 seconds by drilling a 1/32" hole approx 1/32" deep.However it appears as tho you will need to use a 6' launch rod to get to a stable flight velocity..Seemed to really like the H128-6 with a nice gentle deployment speed..

View attachment Gary's_Loc_PK-48_Loc_IV_Extension_fin-c.rkt

I played with design you posted a little;
I stretched the payload section a bit, increased the fins a tad, & made it a 38mm mount.



JD

View attachment myLoc_IV Redesign garys.zip