Estes Ascender with Pro Series Booster -- acceptable thrust-to-weight ratio with F15?

Anyone with an Estes Pro Series II E2X Ascender and Pro Series II E2X Booster:

I had many successful launches of my Ascender with an F15 BP motor. I decided to add the booster. My first and only flight with the booster was a disaster, with the rocket being totally destroyed.

The Ascender itself weighs 11 oz. (311.8 g.). I do not know what the booster weighs, or what an F15-6 and an F15-0 weigh, but I am wondering if the combination of the rocket, booster and two motors exceeeds the recommended 5:1 thrust-to-weight ratio?

Anyone know?

I think I answered my own question. According to a conversion chart, a thrust of 15 can handle at most 11.4 oz. (at a 5:1 ratio). So obviously adding the booster and another motor exceeds 5:1.

So, my next question is this: since the rocket struggled to get off the pad, I obviously would have needed more thrust. Could I have used a composite G motor, minus the ejection charge, as a first stage booster? Anyone ever tried that?

In a different Thread, JeromeK99 told me that the F15 has a Max Liftoff Weight of 21oz.

I don't think the 15 N average thrust is what you need to look at to determine the safe takeoff weight. I don't have the thrust curves at hand, but the peak thrust is higher than the average thrust, and the thrust in the first fractions of a second before the rocket leaves the rod is more important than the average thrust. It seems unlikely Estes would sell a booster for these rockets and these motors that would not work with the F15-0 to F15-6 combo. What exactly happened with the flight?

Bat-mite said:

Anyone with an Estes Pro Series II E2X Ascender and Pro Series II E2X Booster:

I had many successful launches of my Ascender with an F15 BP motor. I decided to add the booster. My first and only flight with the booster was a disaster, with the rocket being totally destroyed.

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You haven't described the flight to us. What happened? What was the flight path? Did it go unstable? Or just ballistic into the ground? What was the wind speed at launch?

Without that information it would be early to assume that it had anything to do with liftoff mass.

That said, however, I do note that the listed weight of the rocket (11oz) and the two motors (just under 7oz) is barely less than the recommended liftoff weight of the F15-0, which is 19oz according to the 2014 catalog. The weight of the booster is not listed, but I would think it would be at least 2oz, and probably nearer to 3 or 4, which would bring the total stack up to 22oz.

I have seen a couple of two-stage Ascender flights, and have noted how slow they are at lift off. One of the flights had turned to less than 45 degrees from the ground by the time the second stage ignited.

Hard to say if this is an example of good test flights in thin air (Penrose is at 5300 feet MSL, vs the flights I've seen which were at 900 feet MSL).

Thanks, all.

It was an extremely windy day, and I was using a 1/4" rod instead of rails, and the rod was bending in the wind. It was a club launch, and they probably should not have been flying in wind that high. So that may have been the issue.

I, unfortunately, did not see the launch. I was fooling around with my new camera, trying to get a video of the flight. I lost it completely, and by the time I let go of the camera to look, it had come down.

What was described to me was that it struggled to get off the pad, ended up about parallel with the ground, and then the chute never ejected and it flew like a ground-to-ground missle.

When I found it, it had burned up. The body tube was burnt to a crisp. The fins were melted and all over the field. The shock cord was burned.

I was able to recover the booster (unharmed) and the chute (unharmed). The rest was just pieces.

The reason I am asking is because I want to know, if I should get another PS II E2X model and try again, will the same thing happen.

One though is to put rail buttons on it. Another is to use a bigger motor in the booster, but that would mean a composite, since the F15 is the biggest BP motor Estes makes, no?

So I am windering if a two-stage flight is possible with a composite motor in the booster.

It sounds like the winds were too high for this kind of motor and rocket combo. I've had slightly underpowered longer burning rocket/motor combos fly great on a calm day but weathercock badly and crash in a breeze, and from what you are describing it was very windy. Doesn't 2 F15's have a combined burn time of about 8 seconds? If something like that gets off to a cruise missile flight, it's gonna crash for sure, and probably hit the ground under power. In fact, I would guess that is what happened to yours --- hit the ground with a few seconds of burn time left, tore the motor mount loose, and the engine burned inside the BT.

I'd say get another one and try it again on a calm day. If it's windy, maybe try it single stage with a composite for a nice solid kick! I've been using
Econojet Fs in my Leviathan which probably weighs twice the weight of your Ascender. They work well enough on calm days, but are kind of marginal in the Leviathan on a windy day. I'd bet they would be perfect in your lighter rocket in the wind. In general, if windy, I'd avoid anything that burns long and go for options that burn fast and strong for good speed off the rod and a straighter flight --- so use an E12 BP or an E20 composite instead of E9 in a 24mm rocket, and use F20, F27, F42, etc. instead of F15 in your rocket. I like long-burning motors but not in the wind.

On your other question: There is already another thread started just yesterday about the problems of composite to BP staging, so maybe look that up.

We know the wind is a problem but I did not see the rod length. Most of us prefer six foot long 1/4" rods pand we make sure they are clean and /or lubed.

Something with marginal thrust should NEVER be flown in high winds.

Other than that, I'm wondering about why your rocket was "burned to a crisp" with melted fins. If the upper stage motor had performed properly, the only damage should have been crash damage (i.e. crushed tube and nose, maybe a broken fin). Even if the crash had totally contained the ejection charge within the body, the wadding and lack of available oxygen wouldn't have let any flames get started for very long. The description you gave kinda, sorta, but not totally, describes a flight where the upper and lower stage motors were swapped. In other words, the upper stage motor in the booster and the F15-0 in the upperstage. Where was the booster recovered in relation to where the rocket crashed?

A rail would probably not have meant much difference in this case. A 1/4" rod for an Ascender is plenty. Maybe the rod was too short, but the rocket just simply shouldn't have been flown.

A composite motor is not set up to ignite upper stage motors.

Please don't take this the wrong way, and forgive me if I assume too much, but the things you've said make it sound like you haven't completely "gotten" the basics of model rocketry, and it bothers me that people are getting high power certifications without a good knowledge of the basics.

Thanks, Roy. I would suggest that if you think people are getting HPR certs too easily that you bring that to the attention of the NAR BOD. Honestly, to get a Level 1, all you have to do is fly something with an H in it and recover it. The Level 2 exam is much more comprehensive and covers many of the situations that often come up in these types of forums.

I am sure that I did not reverse the motors. I had not flown a rocket since December, and it was March, and I was excited to try my new booster. In hindsight, I should not have flown in that wind. Chalk that up to a three-month layoff due to weather cancellations. Due to my fumbling with my camera, I did not witness the launch. The LCO said over the PA that I needed more thrust off the pad. Hence my questions.

Regarding the reversed motors idea, I'm thinking someone would have recognized that kind of flight immediately and made note of it at the time.

My theory on the burnt tube and melted fins is that it crashed under power forcing the motor into the BT and burning it from the inside.

My theory for why it crashed is it was too windy for a slightly marginal long-burn motor combo that would have flown perfectly in calm conditions.

Another possibility is that the launch lugs could have bound slightly on the rod. I've noticed for some of my Estes models that the 1/4 inch lugs are just barely 1/4 inch, and they will bind when loading the rocket if the rod is not perfectly straight. If the wind was strong enough to put a curve into the rod, then possibly the rocket could experience a lot of friction sliding up the rod. It might leave the rod too slowly or induce a nasty rod whip that would throw the rocket off course.

But with all of these theories and possibilities, without actually seeing the flight or the remains of the rocket, who knows?

Bat-mite said:

Thanks, Roy. I would suggest that if you think people are getting HPR certs too easily that you bring that to the attention of the NAR BOD. Honestly, to get a Level 1, all you have to do is fly something with an H in it and recover it. The Level 2 exam is much more comprehensive and covers many of the situations that often come up in these types of forums.

I am sure that I did not reverse the motors. I had not flown a rocket since December, and it was March, and I was excited to try my new booster. In hindsight, I should not have flown in that wind. Chalk that up to a three-month layoff due to weather cancellations. Due to my fumbling with my camera, I did not witness the launch. The LCO said over the PA that I needed more thrust off the pad. Hence my questions.

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Well the part about the thrust off the pad is correct, though in low wind I've seen it fly nicely.

I'm still puzzled about the burning, though. Did you examine the upper stage casing to see if maybe you had a burn-through? That's the only other thing I can think of that would both seriously alter the flight path, and burn/melt a significant portion of the rocket. Or maybe the engine block failed and the motor ended up forward which could have burned up at least the motor tube and fin tabs.

The certification issue is certainly not a new one. When I made my first high power flight in 1991, it was called a "Confirmation" (of what?), and after that I could go buy an M if I wanted! The NAR's first HP cert program was "fly a G, get an H; fly an H, get an I..." and so forth, but it was still just "fly and buy" with no knowledge and skills testing. The Level 2 test is mostly just testing knowledge of regulations, with a little bit of testing knowledge of stuff that's a bit HP specific, though it does cover clustering.

Just read Thirsty's latest reply, and agree that the most likely scenario is that the crash forced the motor forward into the rocket while it was still thrusting.

ThirstyBarbarian said:

Regarding the reversed motors idea, I'm thinking someone would have recognized that kind of flight immediately and made note of it at the time.

My theory on the burnt tube and melted fins is that it crashed under power forcing the motor into the BT and burning it from the inside.

My theory for why it crashed is it was too windy for a slightly marginal long-burn motor combo that would have flown perfectly in calm conditions.

Another possibility is that the launch lugs could have bound slightly on the rod. I've noticed for some of my Estes models that the 1/4 inch lugs are just barely 1/4 inch, and they will bind when loading the rocket if the rod is not perfectly straight. If the wind was strong enough to put a curve into the rod, then possibly the rocket could experience a lot of friction sliding up the rod. It might leave the rod too slowly or induce a nasty rod whip that would throw the rocket off course.

But with all of these theories and possibilities, without actually seeing the flight or the remains of the rocket, who knows?

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I think this is the winner.

I have a few frames of video of it, and it looks like it started to weather cock immediately off the pad. Also, I looked at my pictures of the aftermath, and I was wrong about the fins and the lower section. They were not burnt/melted, only the upper section (payload bay).

FWIW, in my experience the maximum rocket weight for the F15, not including the motor, is 16.000 oz., using a 6' rod. Maybe I'm exaggerating with the 3 decimal places ...

The booster does have big fins on it, maybe so large due to expected low speed? Also, didn't Estes recall the E2X boosters for some smaller rockets?

My Estes Ascender single stage & 2 stager at Desert Heat 2014 - 2 stager still out there somewhere!

F15-0 & F15-6 Nice slow liftoff, slight weathervane before sustainer, deployed ok but unable to find it after three searchs


Craig

No, Estes did NOT recall the E2X boosters for some smaller rockets. They recalled two of the rockets that could be used as upper stages with the E2X boosters since there was a chance that they could be unstable. They re-issued those 2 rockets with nose weight using a new UPC. The boosters were never recalled.

bill_s said:

FWIW, in my experience the maximum rocket weight for the F15, not including the motor, is 16.000 oz., using a 6' rod. Maybe I'm exaggerating with the 3 decimal places ...

The booster does have big fins on it, maybe so large due to expected low speed? Also, didn't Estes recall the E2X boosters for some smaller rockets?

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Here is a motor comparison for a few motors.

The E12 may be a better pick (or D12 for that matter), because it is lighter, and the higher and quicker initial thrust.

One of the issues with the F15 is it takes a looong time to come up to pressure (the E16 is worse). It's better to have a hard hitting spike for heavier rockets followed by a short sustain phase, then a gradual spike and a long sustain phase.

I threw in an AP motor in the midst of BP motors so you could see the typical regressive thrust curve found in so many of the AT Hobby Line reloads.





Greg

Thanks, Greg. That's very useful.

Sadly, last night I looked for my booster and couldn't find it! I am pretty sure I brought it home, but where it ended up, I have no idea. If I can't find that, then this becomes a moot point. Very frustrating.

Thanks again.

Bat-mite said:

Thanks, Greg. That's very useful.

Sadly, last night I looked for my booster and couldn't find it! I am pretty sure I brought it home, but where it ended up, I have no idea. If I can't find that, then this becomes a moot point. Very frustrating.

Thanks again.

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Maybe the booster felt somehow responsible for the loss of the upper stage and is now hiding out of guilt and shame.

ThirstyBarbarian said:

Maybe the booster felt somehow responsible for the loss of the upper stage and is now hiding out of guilt and shame.

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Maybe it's the nose cone of shame?

:eyeroll:

:grin:

ThirstyBarbarian said:

My theory for why it crashed is it was too windy for a slightly marginal long-burn motor combo that would have flown perfectly in calm conditions.
Another possibility is that the launch lugs could have bound slightly on the rod. I've noticed for some of my Estes models that the 1/4 inch lugs
are just barely 1/4 inch, and they will bind when loading the rocket if the rod is not perfectly straight.

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I've seen both of these issues with the D-Region Tomahawk. It's heavy for the 24mm motors so it needs a calm day and the launch lugs are very tight on the rod.

I flew it once in marginal conditions and it did exactly what the OP described - popped off the top of the rod - turned a sharp 90 degrees to the left and hit the
ground under power 100ft from the rod. Luckily for me it only resulted in a small crease in the body tube (soft muddy ground) which I've repaired and also added bigger lugs.

Since then I've flown it in calm conditions on an E9 with no issues.

My experience with a 2-stage Majestic:

On the first flight due to a concern about overall stack weight simply judged by handling the stack and the heavy, potentially car denting booster on its own, I launched with an F15-0 to E16-8; launch day winds were calm, an all too rare occurrence; beautiful flight with no weather cocking and a perfect recovery; the Majestic really screamed upward after booster separation.

On the second flight I risked a 20g heavier F15-8 in the Majestic; the winds weren't perfectly calm, variable but not extreme at ground level; rocket hit winds about 50ft above ground level and took what became a 60 degree or so flight angle just before booster separation at which time the Majestic screamed off at that angle right into the sun; deployment was heard, but nothing ever seen of the Majestic; pretty certain that the recovery gear separated from the rocket at that flight angle and resulting velocity.

From now on, for me, no more flying a Pro Series II multistage in anything less than perfect calm.

What rod was used? Was it a six foot long steel launch rod or the shorter Estes rod?

Winston said:

My experience with a 2-stage Majestic:

On the first flight due to a concern about overall stack weight simply judged by handling the stack and the heavy, potentially car denting booster on its own, I launched with an F15-0 to E16-8; launch day winds were calm, an all too rare occurrence; beautiful flight with no weather cocking and a perfect recovery; the Majestic really screamed upward after booster separation.

On the second flight I risked a 20g heavier F15-8 in the Majestic; the winds weren't perfectly calm, variable but not extreme at ground level; rocket hit winds about 50ft above ground level and took what became a 60 degree or so flight angle just before booster separation at which time the Majestic screamed off at that angle right into the sun; deployment was heard, but nothing ever seen of the Majestic; pretty certain that the recovery gear separated from the rocket at that flight angle and resulting velocity.

From now on, for me, no more flying a Pro Series II multistage in anything less than perfect calm.

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shreadvector said:

What rod was used? Was it a six foot long steel launch rod or the shorter Estes rod?

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In both cases, a 4' rod. Note that the diversion from vertical flight in the second case didn't start until it hit winds about 50 ft AGL.

EDIT: Sim data - I just used the Majestic.ork file I'd found somewhere here previously, did a mass override to add the weight of the booster (136g) and the F15-0 (94g), taking the "empty" weight from 244g to 474g, then I loaded an F15-8 into the adjusted Majestic. Here are the simmed velocities off the rod with no wind:

48" rod (simmed @ 40" to approximate off-pad elevation and forward location of lower launch lug) - 25.6 ft/s
72" rod (simmed @ 64" to approximate off-pad elevation and forward location of lower launch lug) - 31.5 ft/s

Neither very good due to the total stack weight and the slow 0.5 s thrust buildup of the F15.

Attached is my OR file of the Ascender with Booster and a Altimeter 2. I intend to fly this with and without the upper body tube. With the UBT sims out at about 1900 ft and without 2100. Also the stability is much improved without the UBT. My goal is over 2000 ft and so we will see.

Dan

View attachment Ascender-Booster-Altimeter2-Apr-11-15.ork

Launched the Ascender with booster, F15-6 + F15-0, 6-7 mph winds. Flew without the UBT payload bay. Nice straight flight with recovery 500 ft from the Estes stock 1/4" pad. Altimeter failed so no altitude data.

https://www.flickr.com/photos/dhkaiser/17125937991/

Here is my son's Ascender...

After our first staging attempt...

It was the second flight on the airframe...

Estes sent him a new one...:grin:

KidRockET said:

Here is my son's Ascender...

After our first staging attempt...

It was the second flight on the airframe...

Estes sent him a new one...:grin:

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Inquiring minds want to know. How did that happen? High winds?

I'm thinking that if you are going to stage these rockets, it might be better to put an E12 in the first stage. Estes now has the 24/29mm adapters, and the E12 has a bigger thrust spike than an E16 or F15. Maybe the rocket would get off the pad straighter.