OI812

Hey can anybody tell me what model motor (that I can find at a local LHS) would have the longest run time and does not have the pop to open the chute it does not really matter if it has the pop just wondering if there is one on the shelf that doesn't. Thanks Iam building a a rocket plane that will be carried piggyback then released the motor will be lit in glide. The plane is less than 1 1/2 pounds I figured ya'll would know what off the shelf motor would be best. Thanks Matt

OI812

REALLY no one on here uses motors from the LHS ?

mr_matt

My Feedback: (10)

Longest burn is an E9 (you want the biggest letter with the lowest number for long burn).

It burns about 3 seconds.

IIRC there are no E9s that come "plugged" (that is no ejection charge). You are looking for motors that say like E9-P. the "P" means no ejection charge.

You can still use the motors with ejection you just have to vent the gasses out of the motor tube or it will blow the motor out the back on ejection.

OI812

Thank you sir that gives me good starting point we will see how it goes.

glowhead

Estes used to make a D11-p. I am looking at other companies right now. I am building a fun scale rc Okha. It will use 2 d11-p engines. About 3-4 lbs when complete.

OI812

Could you post some pics also let me know where and how much those motors are thanks Matt

Charlie P.

Anything that ends in a "-0" has no "pop" at the end. It just burns through. The last # is the delay time in seconds.

http://www.valuerockets.com/

https://www.discountrocketry.com/mod...gines-c-9.html

http://www3.towerhobbies.com/cgi-bin...93p?&C=TCR&P=7

http://www3.towerhobbies.com/cgi-bin...?&I=LXF411&P=7

gixer1k

This may be a little late, but that is incorrect.

The zero means there is no delay between motor burn out and the ejection charge, it goes off immediately.

You need to find a plugged motor as an earlier poster said.

sylvie369

Respectfully:

That's not quite correct. A -0 engine (D12-0, B6-0, etc.)does not contain an ejection charge. This is confirmed by the manufacturer here:

http://www.estesrockets.com/media//c...12_Catalog.pdf

(go to page 56, where you will read "Booster engines contain no delay or ejection charge").

An ejection charge in a booster would blow the upper stage clear without lighting the upper stage motor. Instead, as Charlie correctly said, "it just burns through".

Booster motors often act as though they had ejection charges, though, as "burns through" does produce pressure in that direction, often enough to open a parachute despite the lack of ejection charge. That may be the source of your confusion.

gixer1k

I stand corrected.

I had always assumed the ejection charge lit the upper stage motor.

I'm a Level 1, so all my flying is done on Aerotechs.

sylvie369

I'm an L2, so I mostly fly Iand J motors, but it's great fun to burn some BP once in a while, and two- and three-stage BP rockets are particularly fun. You should give it a shot.

MJD

My Feedback: (1)

If you are stuck you can simply cap a booster "-0" motor with 1/8" or so of epoxy, that will prevent the burn-through (which is fairly violent as the motor is at operating pressure when it pops, and it burns things too of course) from doing anything. Same is true for a regular motor with delay and ejection, but you need to scrape out the clay and granular blackpowder first, to get down to the pressed delay composition (grey color).

At 1-1/2 pounds you'll need a D or E motor to make anything interesting happen.

mr_matt

My Feedback: (10)

Respectfully I don't think you want to use booster motors in a rocket glider unless the glider has been built or in some manner prepared for the burn through

MJD

My Feedback: (1)

When you're stuck with booster motors the epoxy cap is a well proven way to make "-P" motors. A dash-P BP motor is nothing more than a booster motor with a clay cap pressed in at high pressure so it doesn't burst forward under operating pressure like a booster motor does. 1/8" cap of epoxy does the exact same job. It's not magic or mystery.

mikes68charger

My Feedback: (34)

OK, I got a ME-163 Kometas my next project.

As some may know its a rocket powered glider, but Mine will be 60in wing around 7 pounds with a 140mph prop speed electic motor set up.

As the back of this plane is shaped and desided or so for a rocket motor, I want to use the Estate D12-0 motors.

I know the motor will not help in the thrust department but I want the smoke/sound effect while takeing off.

So my questions.

1. All I need to do is add epoxe to cap the motor for any blow throw.

2. to Be safe I will make a wall infront of the motor with allumum to keep any heat from going to my lipos. Is this ok? I will put a vent hole in the rear as its needed to cool off the electronics anyway.

3. Whats the best way to ignited this set up in the bird?

Thanks Mike

MJD

My Feedback: (1)

If that is the effect you are looking for, then I would say you might be happier with regular D12 engines with delay and ejection.. BUT, first deactivate the ejections charge by scraping out the clay and loose black powder (it's coarse, like black pickling salt) from the top - which takes all of about 5 seconds - until you have the smooth grey delay element exposed, then simply tamp in some paper or rocket wadding up top as a bit of a heat shield. When the delay element burns through it is quite gentle, whereas a booster motor gives a fairly violent "pop" when it burns through, because when it does so the motor is still at operating pressure (50-60 psi at that point). The beneficial effect of using the regular engines is that the delay will keep pumping out smoke for a few seconds as you climb out. So for visual effect, a D12-7 with the ejection charge deactivated would give you about 2 seconds motor burn and about 7 seconds of smoke.

You can use the Estes igniter, but it takes about 3 amps of current (for a second or less so no worries). A servo and switch off the motor battery will work, and run something like 18 gauge wire out the back to the igniter. Leave a little slack internally, and you can twist the igniter on, then snip and strip the wire to get a fresh connection when it gets messed up.

You are right - at 7 pounds weight a D12 will do almost nothing to power the model, it will just add visual effects.

tomski

My Feedback: (4)

I used Aerotech reloadable rocket motors for my rocket powered glider that I dropped off from a transport plane worked great. The nice thing about glider type rocket engines is that they have a slower boost. The reloads that I used had three different burn times 2.5 sec 5sec and 8 seconds. The casing is a little pricy up front but they last forever. Here is a link from where I got my from. http://www.redarrowhobbies.com/aerot...er_engines.htm

MJD

My Feedback: (1)

Although for special effects only, a black powder motor is a cheap and readily available way to make smoke and fire out the tailpipe. If the motor had to do any genuine work on this model, then you'd need a lot more than typical RC rocket glider motors. Other than the SJ motors with black smoke, the other glider motors (E6, D7, G12 etc) are low smoke propellant and won't do much for creating visual effects. A 7 pound model would need a lot more than even the G class RCRG motors to get a significant boost from the motor. The G12 for example has an average thrust of 12N or a bit under 3 pounds.

clipper

OK, I got a ME-163 Komet as my next project.

As some may know its a rocket powered glider, but Mine will be 60in wing around 7 pounds with a 140mph prop speed electic motor set up.

As the back of this plane is shaped and desided or so for a rocket motor, I want to use the Estate D12-0 motors.

I know the motor will not help in the thrust department but I want the smoke/sound effect while takeing off.

So my questions.

1. All I need to do is add epoxe to cap the motor for any blow throw.

2. to Be safe I will make a wall infront of the motor with allumum to keep any heat from going to my lipos. Is this ok? I will put a vent hole in the rear as its needed to cool off the electronics anyway.

3. Whats the best way to ignited this set up in the bird?

Thanks Mike


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mikes68charger
1. I would add the epoxy cap and then test fire a motor to nake sure all works well.

2. Yes add a bulkhead, centering ring and ply would be enough. Use tape to make a friction fit for the motor. If all else goes wrong, the motor can just pop out.

3. This would depend on how much safety margine you want. You could just tie ignitor to the speed controller but this is not the safest way. I use a r/c e-switch for bungee launched rocket gliders. After you launch, hit a separate Tx switch to ignite the rocket motor. I use a heavy rubber band to load the switch for added safety. I you use a Quest Q2G2 ignitor, you can use the voltage from the BEC. I use a 100 ohm resistor in series with the ignitor to limit possble short circut current.

Hope this helps, Eric





Eric

MJD

My Feedback: (1)

FYI - if the goal is smoke out the tailpipe, don't waste time with D12-0 motors. You'll get less than 2 seconds of effects until the propellant burns out. Use D-12-7 or D12-5 motors, gently scrape out the clay and black powder like I described earlier, then put a thin cap of 5 minute epoxy on top. Voila. The motor will burn for it's nominal time, about 1.7 seconds, then it will continue to pump smoke out the nozzle for another 7 or 5 seconds.. you get much more bang for the buck.

When it is done, it will simply stop - no risk of popping out the front and burning anything, a risk you do have with a booster (D12-0) motor if you goof up the epoxy cap. They don't normally fail however.. I used to work at Estes, and capping "-0" motors with epoxy for RC rocket gliders was standard operating practice and done dozens of times when plugged motors weren't available. But.. if you want longer effects, then use the standard motors with the clay and BP scraped out and an epoxy cap.

This is much less prone to failure - the delay element is a charge of slow burning powder dead-pressed on top of the propellant, and it acts like a pressure bulkhead (like an epoxy cap actually). If you leave it in place, not only do you get a few seconds of smoke, you also don't have to deal with sealing the engine at pressure, like you do if you cap a booster motor. This is the easy road to achieve the desired effect.

I can't tell you any more on the subject.. just try it. If you are nervous, fire one outside the aircraft first.

Standard Estes igniters need about 3 amps of current. A servo and micro switch connecting battery power to the igniter is pretty effective if you want to go electro-mechanical. If not, use a small brushed speed controller (maybe 10A minimum) and an auxiliary channel. Or go like Eric says with the other igniters, they are much more sensitive.