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98mm mongoose- Deployment Opinions

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Trenman

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Hey there all! I have finished what I call the "base" construction of my 98mm bird. The fins are on and all the general base building has been complete. There is still alot left however:
~Tip to tip lamination of fins in 2x2 twill CF
~Finish the avBay- the mockup fits great, time to make the real one!
~Parachutes and nose cone avionics need to be installed

That being said ill break down how I designed this:
~75mm Motormount has been installed. The motor tube is FG and the 98-75mm rings are wood, secured externally with 6 screws around each ring. I am considering installing this permanently, under the carbon.... not sure yet

~900mhz GPS in the nose cone on a custom fab aluminum bulkhead, attached via screws to the nosecone allowing the nose cone to drop as it was designed, into the top of the body tube (No attenuation probs whatsoever).

~Ozark Aerospace (NEW version ARTS 2 and RRC2 Mini for redundancy ) in the AvBay. These will run independently in all respects. Not even from the same power source. Pics will follow

My Question: Is there a greater possibility of damage to the nosecone and avionics contained within from a nose cone ejection of the drogue?

I havent bolted the upper airframe onto the top of the avBay yet.... I will drill after I have considered all aspects of the design since there is no turning back once the holes are drilled....
 

new2hpr

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Why on earth would you spend this kind of coin on a Mongoose 98, then permanently mount a 75 motormount in it? You're missing the whole min-diameter point of the bird.

I think you've heard enough bashing, but it seems like a "tell me how to do everything while I show you how much money I have to blow on a rocket I'm just not ready for yet" project.:2:

Good luck!
-Ken
 

JDcluster

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Agreed!
It is his money & rocket, so he can do whatever he likes...

but why bother with Tip-to-Tip when it's not a minimum diameter rocket any more? It will weigh more; slowing down the rocket. He should have bought a 75mm Mongoose or a 4" Econo Line Competitor 4" would have been the same & can be ordered with CF tubes.



JD

Why on earth would you spend this kind of coin on a Mongoose 98, then permanently mount a 75 motormount in it? You're missing the whole min-diameter point of the bird.

I think you've heard enough bashing, but it seems like a "tell me how to do everything while I show you how much money I have to blow on a rocket I'm just not ready for yet" project.:2:

Good luck!
-Ken
 

Trenman

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If there's one thing I can't stand about this forum is the amount of negativity. God forbid I ask for instruction or an opinion. I am USUALLY met with negativity and people who tell me I can't.

This is why I am asking for opinions. This is why I wrote that "built it to be removable and was THINKING about permanent mounting.

I am building my rocket the way I see fit. If you must deviate from the original question in my post than keep your negative and thoroughly discouraging opinions to your selves.

I am a ducati collector an tech, I have been a pilot for ten years and I am in law school at U Penn. I am NOT a rocket scientist but I'll be damned if others imply that my projects are being built incorrectly when they are simply being built the way that makes me HAPPY. This is a hobby.

If anyone has anything HELPFUL to write kindly leave a post that has some substance. Otherwise the back arrow is up
on the top left.

This is the #1 most discouraging forum I'm sad to say. I've been in defence mode since I've joined

Regretfully, trenman
 
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Trenman

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And the other reason I chose a 75mm motor mount is so I can use it in a L2 fashion and for a L3 attempt. The mmt weight 1.3 lbs which despite the comment above does not add much weight as a 98mm in minn diameter fashion would. So the weight theory is quite irrelevant.


I cannot wait to reveal this bird for the first time. I live it when I
show people ignorant of my abilities what I am made of. Continue to put me down, and watch how you make me want it worse. You will eat your words soon enough.


Now will some clever fellow answer my original question... Of you feel I haven't been put down enough, then reread basically any post I've ever posted and count all the negative feedback up.
 

ben_ullman

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Trenman, read some of my old posts from way back when. I thought I was one stubborn kid, you have beat me in this dept. I was told I couldn't and tried anyways. I think I got lucky with alot of things and failures.

Don't mount a permanent 76. you will regret it and you are wrong. a 98mm MD bird with a 76mm ADAPTER will be lighter than a mounted 76mm.

Ben
 

Trenman

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Trenman, read some of my old posts from way back when. I thought I was one stubborn kid, you have beat me in this dept. I was told I couldn't and tried anyways. I think I got lucky with alot of things and failures.

Don't mount a permanent 76. you will regret it and you are wrong. a 98mm MD bird with a 76mm ADAPTER will be lighter than a mounted 76mm.

Ben
with respect, stubborn people don't ask for advise. I want advise, just not with the tone and attitude that my ideas are somehow inferior. I wouldn't be posting and asking for help on a subject that I know far less about than most people on this board. Condescending remarks are not only inappropriate but are extremely unnessecary. I never said I was going to permanently mount a 75mm motor mount tube. I said I was thinking about it. The reason I did that was for constructive feedback if others felt there was a better way. I told wildman that I couldn't find a min diameter motor retention system and HE reccomended doing it this way. With 12 screws I can remove the motor adapter for future 98mm flights. As of now I am content flying 75mm because I can fly with an L2. I dont have any plans on going for an L3 anytime soon. When I do I'll have the option. Until then where is the harm in making a 1.3lb removable motormount so I can have best of both worlds? I'm asking for helpful ideas. Not harsh and condescending criticism for my ignorance. Do we
all not start somewhere!?
 
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ben_ullman

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put an aeropack on it. And you can fly 98mm with an L2. They make 1 and 2 grain loads.

Ben
 

TheAviator

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Here is your advice:

Mounting the electronics in the nose cone will not make them any more prone to damage, as long as everything is cushioned properly. The only time when more damage would come is on a ballistic impact, and the electronics are likely to be toast anyways, especially with this sleek of a bird.

Second, if I recall correctly, the 75mm and 98mm AT motors are fitted with a tapped forward bulkhead, which means you can attach the recovery harness directly to the motor via a FORGED eyebolt. (Emphasis on forged as a machined/welded eyebolt will fail under the loads you are putting on this rocket.) I don't know the specifics because I don't have nearly the money to work with that size of motor, but I'm no stranger to HPR either.

Third, I would place the main in the nose/payload section and the drogue in the lower body so that the main doesn't get tangled in the nose and drogue rigging.

Finally, yes, we do all start somewhere. My first rocket was an Estes Generic E2X rocket that I received in a science club in third grade. I never kept track, but I know I've made several hundred flights since then. How 'bout you?
 

Trenman

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Id say probably not so many as you sir. I would say a rocket every quarter for 12 years or more, im 26. Your feedback was both helpful and appreciated. Im afraid I was told an aeropack wont fit, and it looks like thats the case with the brief research i did.


Once again thank you. I appreciate your help. :cheers:
 

madmax

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An Aeropack won't fit on the 98mm airframe but you could use a tailcone retainer on the 75mm adapter. Slimline makes a retainer I believe will work but it will overhang the airframe that means no tower launches. Rails will be ok with some offset to the buttons like some washers under them to clear the retainer.

I also strongly recommend putting the drogue in the lower airframe and the main in the upper. There ought to be more room for the laundry in that configuration. Avionics in the nose should not be damaged by deployment unless the force would be enough to rip that bulkhead out...or a lawn dart! Nothing usually survives those! Even motor cases!
 

JDcluster

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Hold on there, you are taking this forum way too seriously.
One part about asking for advice is learning to accept constructive criticism.
You post is about the entire rocket & we commented about one part of it
and wasn't to your liking.

You asked for an opinion & we presented you with one, & only suggested it.
Then you lash out at us for giving you an opinion.


Now back to our featured presentation:

The electronics should be fine as long as it's secured well enough in the nose cone. (I've never really mounted them up there). The only real problem would be; with barometric venting for low altitude deployment feature.
You mentioned the ARTS 2 & a Missile Works Mini. The Mini will mostly likely need mach delays, even if it isn't going that fast.



Take it with a grain of salt. Take a step back & look at it from another angle.
Your hubris may have gotten the best of you.


JD


If there's one thing I can't stand about this forum is the amount of negativity. God forbid I ask for instruction or an opinion. I am USUALLY met with negativity and people who tell me I can't.

This is why I am asking for opinions. This is why I wrote that "built it to be removable and was THINKING about permanent mounting.

I am building my rocket the way I see fit. If you must deviate from the original question in my post than keep your negative and thoroughly discouraging opinions to your selves.

I am a Ducati collector an tech, I have been a pilot for ten years and I am in law school at U Penn. I am NOT a rocket scientist but I'll be damned if others imply that my projects are being built incorrectly when they are simply being built the way that makes me HAPPY. This is a hobby.

If anyone has anything HELPFUL to write kindly leave a post that has some substance. Otherwise the back arrow is up
on the top left.

This is the #1 most discouraging forum I'm sad to say. I've been in defiance mode since I've joined

Regretfully, trenman
 

dixontj93060

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Trenman,

JD is right, you can fly with electronics in the nosecone although you have to be very careful on setting delays (and, frankly, it would be better just to use accelerometer-based altimeters). In any case, I have done it on at least three different designs for differing reasons. I'm not in my office today (where I have my pictures archived), but I'll try to post a couple tomorrow.

On the other subject, from what I have observed, this forum is like many others on the Internet where the principal "Giver's gain" applies, i.e., post and post liberally detailing your approaches and designs (both in pictures and prose). Once you "give" you will "gain." Now that doesn't mean you won't get criticism and in fact, the more detail you show, you open yourself up to added scrutiny, but in the end it works out on balance to the positive side.

Cheers,
Tim

The electronics should be fine as long as it's secured well enough in the nose cone. (I've never really mounted them up there). The only real problem would be; with barometric venting for low altitude deployment feature.
You mentioned the ARTS 2 & a Missile Works Mini. The Mini will mostly likely need mach delays, even if it isn't going that fast.
JD
 
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gr3456

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Hey Trenman,
Thanks for starting this thread on the mongoose 98. I will be reading and waiting
for some pics. I also just received the 98 and Wildman also suggested the adapter for the 75 mm. Not that I don't want to fly the 98mm cause I already have the casing. He told me that it will break any waiver we have around here so my level three launch with this bird will have to wait until I get to a launch with a adequate waiver. So I am going to sit back and watch to get some ideas
of how you are doing the adapting and see what problems or issues occur. It
says on the 98 pdf that it will fly on J thru O's. I may have to fly it on a J just
to see it fly and fix any issues through that testing. So please keep posting your
progress.
 

rocketsmith

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Hold on there, you are taking this forum way too seriously.
One part about asking for advice is learning to accept constructive criticism.
You post is about the entire rocket & we commented about one part of it
and wasn't to your liking.

You asked for an opinion & we presented you with one, & only suggested it.
Then you lash out at us for giving you an opinion.


Now back to our featured presentation:

The electronics should be fine as long as it's secured well enough in the nose cone. (I've never really mounted them up there). The only real problem would be; with barometric venting for low altitude deployment feature.
You mentioned the ARTS 2 & a Missile Works Mini. The Mini will mostly likely need mach delays, even if it isn't going that fast.



Take it with a grain of salt. Take a step back & look at it from another angle.
Your hubris may have gotten the best of you.


JD
This is exactly why I rarely post here: the self appointed rulers of the rocket universe are all too happy to tell others how it is supposed to be. JD, what exactly was constructive about the comments in the 1st post following the initial topic? To me it is just another jacka** so full of himself that he just has to pipe up at every opportunity to put others down and justify his pathetic existence. It's so easy to throw barbs from the safety of one's own office, protected by the distance and annonimity of the internet. There are about a dozen guys who post here all the time that need to turn off the computer, go outside and interact with real people. It's because of this kind of garbage that makes me say 'this forum sucks a fat one."
 

Handeman

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This is exactly why I rarely post here: the self appointed rulers of the rocket universe are all too happy to tell others how it is supposed to be. JD, what exactly was constructive about the comments in the 1st post following the initial topic? To me it is just another jacka** so full of himself that he just has to pipe up at every opportunity to put others down and justify his pathetic existence. It's so easy to throw barbs from the safety of one's own office, protected by the distance and annonimity of the internet. There are about a dozen guys who post here all the time that need to turn off the computer, go outside and interact with real people. It's because of this kind of garbage that makes me say 'this forum sucks a fat one."

I have nothing invested in this thread, but I read this thread when there were just the first three posts. I had the same thoughts about Ken & JD's post #2 & #3 as Trenman and you had.

Right now, I'm not sure your post doesn't fit into the same category as Ken & JD's. Trenman made it perfectly clear how he felt about the posts and I support him in that. Your post, although couched in general terms, seems like a personal attack that isn't really warranted and seem more like you venting then trying to help the situation.

Now I'll shut up about it too.
 

troj

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That being said ill break down how I designed this:
~75mm Motormount has been installed. The motor tube is FG and the 98-75mm rings are wood, secured externally with 6 screws around each ring. I am considering installing this permanently, under the carbon.... not sure yet
What's your goal? Maximum performance, or something you're more likely to fly?

If your goal is to maximize performance of the rocket, then leave 98mm as an option. If you're more likely to fly 75mm and don't want to monkey with an adapter, then put in the 75mm. Allowing it to be removed, but having it available gives you flexibility, even if you never remove it.

~900mhz GPS in the nose cone on a custom fab aluminum bulkhead, attached via screws to the nosecone allowing the nose cone to drop as it was designed, into the top of the body tube (No attenuation probs whatsoever).

~Ozark Aerospace (NEW version ARTS 2 and RRC2 Mini for redundancy ) in the AvBay. These will run independently in all respects. Not even from the same power source. Pics will follow

My Question: Is there a greater possibility of damage to the nosecone and avionics contained within from a nose cone ejection of the drogue?
If it were me, I'd keep the altimeters away from the GPS. It's just not worth the risk of interference. Your GPS, and your avionics, will all do well in the nosecone -- keep our friend Newton in mind. You're going to get the same load on both ends when the charge fires, so it doesn't matter if they're in the tube or in the nosecone, they're going to get the same amount of energy transmitted to them.

Regardless, the key, like in any rocket, is solid mounting, especially since you're building something that's high performance. I've see what happens when an altimeter sled (aluminum) collapses under thrust, and it's not something you want, considering your investment.

The loads from an ejection charge are nothing compared to the loads everything will face from acceleration from the motor.

-Kevin
 

Pantherjon

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snip

The loads from an ejection charge are nothing compared to the loads everything will face from acceleration from the motor.

-Kevin
Not necessarily Kevin..I have seen data from flights where the ejection charge was close to 100g's, whereas the acceleration from the motor was only:rolleyes: 50g's..All depends on how robust one makes their e-charges. Some go by the practice of 'blow it out, or blow it up' for their e-charges..:2:
 

Trenman

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I apologize for my absence. My beloved mother in-law (seriously) was found on the floor of her home by my wife. After an ER visit she remained in ICU with stage 4 lung cancer, pancreatic and adrenal cancer with the complication of pneumonia and diabetes (a total shock considering how active she was). My focus has shifted dramatically to making the last days my wife has with her, the best on earth, so that she may have a lifetime of happy memories.....

As for the back and forth above, I have discovered that the bantering is over a topic which isnt that serious. I didnt mean to anger or annoy anyone. I maintain that i felt personally attacked and belittled but the answer to all that was not to retaliate.

I maintain that I will build my rocket as I see fit. There are different ways to cook a chicken.

As for technical jargon. I seem to have caused some confusion. I have no intention of perusing a L3 at this time. Nor am I that interested in spending hundreds monthly on reloads. This bird WILL be flown many times per year.

Finally, the avionics ive placed in the nosecone are the GPS only. The avionics for deployment are where they traditionally are located (in the middle, above and below the airframes.

Hope this clears some things up.
 

troj

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My focus has shifted dramatically to making the last days my wife has with her, the best on earth, so that she may have a lifetime of happy memories.....
Sounds like you've got your priorities in order. My sympathies to you and your wife on what I'm sure is a trying time.

I maintain that i felt personally attacked and belittled but the answer to all that was not to retaliate.
I don't think anyone meant to attack you; unfortunately, sometimes it comes across that way. But, as you've discovered, there are lots of opinions.

I maintain that I will build my rocket as I see fit. There are different ways to cook a chicken.
Yup! At the end of the day, it's your rocket, and as long as it's safe (I don't have any doubt that your plans are safe), then it's your decision on how to do it.

-Kevin
 

dixontj93060

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Trenman,

Sorry to hear unfortunate news. Yes, best to focus on family at a time like this.

-Tim

I apologize for my absence. My beloved mother in-law (seriously) was found on the floor of her home by my wife. After an ER visit she remained in ICU with stage 4 lung cancer, pancreatic and adrenal cancer with the complication of pneumonia and diabetes (a total shock considering how active she was). My focus has shifted dramatically to making the last days my wife has with her, the best on earth, so that she may have a lifetime of happy memories.....
 

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