Returning to the Hobby after many years - and I have questions

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markfsanderson

markfsanderson

Model Rocketry Returnee ...
TRF Supporter
Joined
Mar 15, 2017
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Location
New Baltimore, VA
Greetings,
Looking for fun that my 5 year old son and I can fun with as well as kindle his interest in the sciences, has led me back to Rocketry. I've re-joined NAR after many years absent, and will be joining a local club that has interest in mid and high powered rocketry. My current is mid-powered rocketry, and perhaps high-power in the near future. It appears that RMS reloadable motors are difficult to find, but I d manage to find an Aerotech 29/40-120 one on Ebay along with some reloads as well:
G53-5FJ
G64-4W
G64-10W
G76-10G

Questions:

1) Can these reloads be modified to reduce their delay from let say 10 seconds to 7? Does the Delay drilling tool accomplish this? Are there ways to increase the delay time?

2) Should I select the rocket based on the reloads themselves? What problems might occur if the delay charge is shorter than it should be? Would a longer/tougher parachute shock cord solve that problem?

2.5) I'm not interested in flying high, mostly in spectacular take-offs . . . what would you recommend as a rocket given that the engines above that I currently have (29mm/40-120).

3) As I'd like to move on to high powered rocketry which utilizes launch lugs and rails, can I outfit a mid-powered rocket like the Arreaux or Initiator with launch lugs?

4) When purchasing one of the rails should it be a single 6' long section? (I plan on making the Apogee home made PVC rail launcher)

Thanks for any advice in advance . . .

Mark Sanderson
 
Reloadable motors can be found from Balsa Machining Service, BuyRocketMotors.com, Wildman Rocketry, Apogee, local vendors at launches, as well as CS Rocketry, OneBadHawk (Loki) and others.

1) yes the delay times on RMS, DMS and CTI motors can be modified, and each has there own Delay Drilling tool, however a regular 1/4" drill bit will do the same thing (1/32" drilled is 1 second removed approximately).

2) Motor selection is usually based on the rocket, since its weight and form determine the motors requirements to fly safely.

2.5)The rockets listed in question 3 will work fine as will most any PSII Estes rocket, or Loc Precision or Madcow cardboard rockets under 3" (usually, my opinion is that even many 1.6" fiberglass rockets are marginal on most G motors) but lightweight 3" shorter rockets will work well. There are many other choices too.

3) I rarely build using launch lugs any more, now that there are rails in 10mm, 20mm, 1", 1.5" and UniStrut. I now buy the majority of my railbuttons from www.rail-buttons.com , Randy has excellent service and selection to fit all the listed rails except UniStrut, most clubs generally have 1" (1010 standard) and 1.5" (1515 rails). All of my MPR rockets that have 29mm mounts are fitted with 1010 buttons.

4) I like 5' for my 10mm MakerBeam and 20mm rails, 6' for my 1010 MPR and 8' min for my 1010 rails for HPR. So yes 6' is fine for most MPR and some HPR (it comes donw to usable rail length and rail exit speed of the rocket....is it stable at rail exit).
 
Following on Rich, several people here have made excellent launchers out of a JawStand, a piece of 1010 rail, a few nuts and bolts, and a pizza lifter as a blast deflector.
 
Rich,
Thanks for the great info! Can the ejection charge delay be increased for the Aerotech RMS motors in some fashion?

Thanks again!

Mark

QUOTE="rharshberger, post: 1838748, member: 18236"]Reloadable motors can be found from Balsa Machining Service, BuyRocketMotors.com, Wildman Rocketry, Apogee, local vendors at launches, as well as CS Rocketry, OneBadHawk (Loki) and others.

1) yes the delay times on RMS, DMS and CTI motors can be modified, and each has there own Delay Drilling tool, however a regular 1/4" drill bit will do the same thing (1/32" drilled is 1 second removed approximately).
...
[/QUOTE]

Thanks
 
the Aerotech rocket kits come with launch lugs sized to use 1/4" rods(as do a number of rockets in that size range), however given the size and weight, rail buttons would work well too.
the short answer about delay times is that they can be shortened a bit (iirc down to a 4 second delay) but cannot be extended beyond their stated delay time. mismatching delay times will result in having the recovery system deployed while the rocket is moving at high speed, this tends to damage things.
Rex
 
The LOC Onyx is an awesome little rocket for the 29/40-120 case. The new version has been upgraded with through the wall fins so no worries with them breaking off. Plus kids seem to like short stubby little rockets.

Welcome back to the fold. We will be glad to help you spend your money.
 
A club should have all the launch equipment you need, so building your own high power pad may not be worth the effort. However, if you can find a space to launch up to G motors then a pad would allow you to go out on your own and launch.

Remember H motors and up require an FAA waiver to launch. Some G motors fall into high power requirements and clusters can too, so be careful.
 
markfsanderson said:
I don't understand whatI'm looking at in relation to increasing delay charge times . . . an explanation would be appreciated . . . Thanks!
Click to expand...

Those are the delay kits you can purchase to lengthen/ shorten the delay time. https://www.siriusrocketry.biz/ishop/aerotech-hobby-delay-kits-hdk-90/hobby-delay-kits-for-29mm-motors-104/
Example: To make a G64 delay 10 seconds long you need a HDK-21

Like mentioned to shorten the times you can drill them. Best to buy the reloads with the longest time available and then drill to desired time no need to spend extra $ for the delay kits. Do you have a sim program? The program will give you an idea of the delay you need. Most of the delays available with the reloads work well without doing anything to them.
 
Last edited:
1) Can these reloads be modified to reduce their delay from let say 10 seconds to 7? yes, use the Delay drilling tool, the drilled end faces the propellant. Does the Delay drilling tool accomplish this? yes. Are there ways to increase the delay time? you can buy a longer delay for some motors. delays are usually specific to the motor type; for example a ten second delay grain for the G53-5FJ is probably not the same delay grain as a ten second delay for the G64-4W

2) Should I select the rocket based on the reloads themselves? usually I select the motor based of the rocket, but I guess since you already have the motors, sure. What problems might occur if the delay charge is shorter than it should be? ejection at high speed is bad can cause zipper damage and/or destroy the rocket or chute Would a longer/tougher parachute shock cord solve that problem? no. it might not damage the chute but it could tear through the tube.

2.5) I'm not interested in flying high, mostly in spectacular take-offs . . . what would you recommend as a rocket given that the engines above that I currently have (29mm/40-120). 2.6" and Lighter 3" cardboard rockets are good for moderate high on a G motor and are paper tubes and wood fins so basically build like a large Estes rocket, using wood glue will be fine.

3) As I'd like to move on to high powered rocketry which utilizes launch lugs and rails, can I outfit a mid-powered rocket like the Arreaux or Initiator with launch lugs? yes definitely. some clubs even will not allow any G motors unless flown off a rail. (no rods allowed for F or higher impulse)

4) When purchasing one of the rails should it be a single 6' long section? (I plan on making the Apogee home made PVC rail launcher. A single section is better, although most clubs will already have a rail for you to use
 
I like the 2.6" diameter LOC kits for G motors. I also have a 4" diameter rocket built from LOC parts that flies well on G motors, the rocket is relatively light since it is about 24" long. Anything smaller than 2.6" diameter might go higher than what you want.
 
markfsanderson said:
Rich,
Thanks for the great info! Can the ejection charge delay be increased for the Aerotech RMS motors in some fashion?
Click to expand...

I'm not aware of any way to increase the delay time for motor ejection, as the length of the delay grain would have to be increased. An altimeter, for ejection at just the right time, or an electronic timer would be needed.

Best -- Terry
 
You can buy longer delay elements to increase the delay time, but it is generally not worth the cost unless you have a local dealer that has them in stock. For existing reloads use them in an appropriately sized rocket. Any new reloads that you buy just get the longest delay available and shorten if needed. If you are not familiar with assembling reloads, have someone assist you for your first few until you get comfortable with the process.
 
Nytrunner said:
Side question, are 29/40-120 hobby line loads delay-adjustable? If they are I guess I missed it.

If they're not, the OP should be made aware
Click to expand...

They use the same delay adjustment tool as regular 18-38mm RMS loads (RDDT) so yes the AT 29/40-120 delays are adjustable and RDK's can be bought to make shorter stock delays into longer ones (as long as that combo is certified of course).

+1 to what terryg said, buy the longest delay and shorten as needed.
 
bjphoenix said:
I like the 2.6" diameter LOC kits for G motors. I also have a 4" diameter rocket built from LOC parts that flies well on G motors, the rocket is relatively light since it is about 24" long. Anything smaller than 2.6" diameter might go higher than what you want.
Click to expand...

I was doing a bit of looking online- the shorter 4" diameter rockets work well on G motors. Aerotech Sumo and Binder Spike are the ones I was thinking about. I see that LOC makes several 4" diameter rockets that they say will work on G motors. LOC makes some 3" diameter kits that might be a good- a combination of high altitude but keep it in sight. This all depends on your launch conditions- high altitude is OK if you have clear skies for spotting, a reasonably large field, and launch in low wind. Small fields and high winds make you want to stay with low altitude.
 
grouch said:
The LOC Onyx is an awesome little rocket for the 29/40-120 case. The new version has been upgraded with through the wall fins so no worries with them breaking off. Plus kids seem to like short stubby little rockets.

Welcome back to the fold. We will be glad to help you spend your money.
Click to expand...

That's a good looking rocket and is certainly '5 year old ' size as well.

Mark
 
rcktnut said:
Those are the delay kits you can purchase to lengthen/ shorten the delay time. https://www.siriusrocketry.biz/ishop/aerotech-hobby-delay-kits-hdk-90/hobby-delay-kits-for-29mm-motors-104/
Example: To make a G64 delay 10 seconds long you need a HDK-21

Like mentioned to shorten the times you can drill them. Best to buy the reloads with the longest time available and then drill to desired time no need to spend extra $ for the delay kits. Do you have a sim program? The program will give you an idea of the delay you need. Most of the delays available with the reloads work well without doing anything to them.
Click to expand...

At $8.00/3 they are not cheap . . . I've fooled around with OpenRocket, I'm assuming I try to match a delay to the calculated minimum speed a the rocket's apogee? I need to do some reading to make sure I fully understand how to read the graphs . . . Thanks!
 
bjphoenix said:
I was doing a bit of looking online- the shorter 4" diameter rockets work well on G motors. Aerotech Sumo and Binder Spike are the ones I was thinking about. I see that LOC makes several 4" diameter rockets that they say will work on G motors. LOC makes some 3" diameter kits that might be a good- a combination of high altitude but keep it in sight. This all depends on your launch conditions- high altitude is OK if you have clear skies for spotting, a reasonably large field, and launch in low wind. Small fields and high winds make you want to stay with low altitude.
Click to expand...

Thanks - I'll take a look at those as well . . .
 
bjphoenix said:
I was doing a bit of looking online- the shorter 4" diameter rockets work well on G motors. Aerotech Sumo and Binder Spike are the ones I was thinking about. I see that LOC makes several 4" diameter rockets that they say will work on G motors. LOC makes some 3" diameter kits that might be a good- a combination of high altitude but keep it in sight. This all depends on your launch conditions- high altitude is OK if you have clear skies for spotting, a reasonably large field, and launch in low wind. Small fields and high winds make you want to stay with low altitude.
Click to expand...

Thanks - I'll look at those as well. For now we'll probably keep the altitude low and the take off fun . . . Those large diameter rockets might just fit the bill!
Mark
 
markfsanderson said:
At $8.00/3 they are not cheap . . . I've fooled around with OpenRocket, I'm assuming I try to match a delay to the calculated minimum speed a the rocket's apogee? I need to do some reading to make sure I fully understand how to read the graphs . . . Thanks!
Click to expand...
+ or - 1 second is okay on the delay usually, by then the rocket has slowed for apogee so a slightly short delay is generally okay, and if its one second longer the rocket has not picked up enough speed to cause damage after hitting apogee.
 
f
dhbarr said:
Hobby loads use the .562" OD HDK, not the .610-.933" OD RDK.
Click to expand...
Quick question - Does the term 'Hobby Loads' include all loads that do not require a NAR/Tripoli High Power certification (High G and better motors)? That is low and mid power motors? I think I know the answer, I just want to make sure I understand the terminology.
thanks!

Mark
 
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