Estes Fat Boy help

[cydermaster]

I got myself an Estes Fat Boy, a little while ago - great laugh to build etc.

I flies well on a B6-2; but put a C6-3 in it, and about 5 metres off the pad it goes almost horizontal, and carries on on this trajectory until ejection.

Anybody else had this? Would adding some weight to the nosecone help?

Thanks in advance.

 

[sandman]

I've seen the Fat Boy do that at a few launches.

I think the nose weight comes loose.

Any short stubby rocket needs nose weight but the clay can come loose. I always add a few drops of epoxy to hold the clay in place.

sandman

 

[cydermaster]

Thanks for the reply Sandman.

The instructions mention nothing about putting weight in the nose, I thought that might be the problem, and you've confirmed that its a direction worth investigating - I'm going to try experimenting with some blu-tack, and then epoxy it in, when I've achieved the right amount.

I'll report back as to what diferance this makes.

 

[powderburner]

I have never (knock on wood) had a FB do that, on any engine, and I probably have made over 50 flights on one incarnation or the other.
I use a larger-diam 3/16 or 1/4 rod for my full-size FB's, and feel that the extra stiffness helps get things off to a better start.
I have also cheated on the last couple of builds and turned the big nose cone into a parachute compartment, getting the chute weight a little further forward, and protecting it against ejection gases better (I think). But a little nose weight wouldn't hurt either.

 

[Stymye]

if it flew well on a b-6 but not on a C-6
powderburners advice is well taken
cydermaster
next time you launch , watch for rod whip

that may be the culprit as much as anythingl

 

[Elbmod]

I've flown my first fatboy an C's many tme and never had a problem. I don't have any nose weight in it either. I reckon your launch rod isn't long enough!

 

[sandman]

That is odd.

I have never had a problem with mine either but, I have seen three others do very unstable loops right off of the pad. Perhaps a slow motion video would reveal results.

Perhaps it is "rod whip". I did notice that one Fat Boy that looped had extra nose weight and it had come loose.

I added some clay and epoxied it into place after seeing others "loop".

It's not a high performer anyway so better to error on safety.

sandman

 

[GoBang]

I've flown my Fat Boys pretty much exclusively on C6s and have never had a problem with stability. I wonder, perhaps, if you might've had thrust vectoring from nozzle deterioration. I had that happen on a couple of models and it looks about like what you describe. I got quite a few in one of the "blast off packs" and three or four of those ended up going horizontal or pinwheeling.

If you still have the motor casing, check it and see if it has a white clay nozzle. If it does, then I would say that's very much a possibility if not a likelihood. I look my motors over carefully before I buy them now and make sure the nozzles are all the newer "mottled clay" variety. I haven't had any problems with instability since.

Just a thought...

jdr

 

[Mike]

I just had a look at all of my motor collection and I have a D12-5 with a white clay nozzle. Are you saying that the motors with white clay nozzles suffer from this deteriation and therefore thrust vectoring?

Can I also ask, what's thrust vectoring?

 

[cydermaster]

Hmmmmm...... A few ideas to work on there - thanks people!

I've still got one engine that I can say definatly powered my Fat Boy - I'm not too sure what I'm looking for, but it does look like its a white clay one, so GoBang's theory might hold true. I've got some more C6-3s in a blastoff pack I got recently, so I'll give one of those a go.

I've got to upgrade my cr@ppy Quest rod, to fly my Fliskits Drake, when its built. That should give it a better start.

If neither of these work, I'll then try the nosecone weight - I'll keep everybody up to date on progress.

 

[GoBang]

Originally posted by Mike
I just had a look at all of my motor collection and I have a D12-5 with a white clay nozzle. Are you saying that the motors with white clay nozzles suffer from this deteriation and therefore thrust vectoring?

Can I also ask, what's thrust vectoring?

Basically the nozzle erodes unevenly and directs the thrust somewhere other than straight down. Not a good thing, needless to say! The model as a result could conceivably go anywhere, and I have seen a few that have flown awful wildly. I either soaked and discarded my old motors or made darned sure I was alone in a big open field when I flew them. The clay was so bad on some that I could pick bits off with my fingernail. On one I actually had the whole thing come apart when I pressed the ignitor plug into place. Yow!

This is actually a pretty long standing issue, so I'm certainly only quoting what I myself have read from others. I'm no rocket scientist. I learned all of this the hard way myself; my first-ever 24mm flight was with a "poopy-clay" D12. My Eliminator pinwheeled merrily but harmlessly about 50 feet off the rod.

I must note too that Estes seems to have corrected the problem; if you look at the newer motors you'll see that the nozzles are a darker clay with a kind of speckled appearance. I have had no problems with these at all, and as previously mentioned, I look very carefully at the motors before I buy them anymore. You can generally tell if they're okay without opening the package, unless it's a Blast-Off pack, in which case, you pays your money, you takes your chances...

jdr

 

[cydermaster]

Originally posted by GoBang
........ you pays your money, you takes your chances...

I can only get motors via mail-order, over here; so its a gamble, anyhow.

That said, looking over my current unspent engines - I'm ok

 

[GoBang]

Originally posted by cydermaster
I've got to upgrade my cr@ppy Quest rod, to fly my Fliskits Drake, when its built. That should give it a better start.

I found a four foot length of welding rod at a hardware store that serves nicely as a launch rod. $1.50 and what do you know, it comes in 1/8", 3/16", and 1/4" sizes. The 1/8" fits into the Quest launcher too, though once it's there it's there to stay, and it does corrode fairly quickly. A little WD-40 and steel wool solves that.

jdr

PS...Portishead, eh? Love 'em. Beth Gibbons is wonderful. She's no Kate Bush, but at least she's released an album in the last 10 years...yeesh.

 

[cydermaster]

Originally posted by GoBang
PS...Portishead, eh? Love 'em. Beth Gibbons is wonderful. She's no Kate Bush, but at least she's released an album in the last 10 years...yeesh.

Oh yeah, the SECOND best (after the Wurzels) musical export from my village. Geoff was at school with me. He was a few years below me, so I didn't know him that well, but we were both into music and being in bands, so we often bumped into each other. Beth actually comes from a town about 5 miles away, called Nailsea, so is really an imposter - but with a voice like that, who cares?!?

IMHO, Dummy is one of the greatest albums EVER. I rank it up with Dark Side of the Moon, Never Mind the B******s - heres the Sex Pistols, Tommy and Who's next.

 

[flying_silverad]

Wait. I think we forgot something here. We are assuming that the CG and CP are correct. It is a stubby little guy so we know they can be less than stable from the get-go.
I say the first thing to do (and the cheapest) is to pack a motor in it, stuff some wadding and a chute in it...cork it..and perform a swing test.
If it behaves, then go on to the next possible cause

 

[powderburner]

That sounds entirely too rational.

Next thing you know, you'll be wanting us to build a wind tunnel, and three-axis sting, and video data collection system.

I believe the FB has been field-tested by enough rocket hobbiests (to say nothing of the product testing required by the lawyers at Estes) to pronounce that particular design STABLE. While it certainly won't hurt anything to swing-test, I anticipate that such a test will be inconclusive. Short/fat rocket designs with marginal stability margins are notorious for not testing consistently with the 'ol swing test.

I will still put my bet on a wimpy launch rod as the cause of most of the problem. Cydermaster, what does a 1/4 inch (sorry, I meant 7mm) launch rod cost over there? I will sponsor one for you, that's how sure I am where the problem lies.

 

[astrowolf67]

I've got to upgrade my cr@ppy Quest rod, to fly my Fliskits Drake, when its built. That should give it a better start.

Just out of curiosity, is your Quest pad one of the older ones made from PVC? If it is, the rod could definately be your problem. The one I have from a Quest starter set, is a smaller diameter on the upper section. I would replace it with a longer rod from a hardware store. I use a steel 4 ft rod for 1/8" and 3/16".

Others have mentioned a swing test for stability. My Fat Boy has never passed the swing test, yet flies beautifully every time. It is converted to 24mm, with 2 oz of nose weight, and has flown on D12's, and E11's so far. Next launch, I'm planning on an E9 flight, and an F21. One last note, it has a 1/4" lug.

 

[flying_silverad]

Originally posted by powderburner
That sounds entirely too rational.

Next thing you know, you'll be wanting us to build a wind tunnel, and three-axis sting, and video data collection system.

I believe the FB has been field-tested by enough rocket hobbiests (to say nothing of the product testing required by the lawyers at Estes) to pronounce that particular design STABLE. While it certainly won't hurt anything to swing-test, I anticipate that such a test will be inconclusive. Short/fat rocket designs with marginal stability margins are notorious for not testing consistently with the 'ol swing test.

I will still put my bet on a wimpy launch rod as the cause of most of the problem. Cydermaster, what does a 1/4 inch (sorry, I meant 7mm) launch rod cost over there? I will sponsor one for you, that's how sure I am where the problem lies.

Hmmm...

 

[cydermaster]

Originally posted by astrowolf67
[BJJust out of curiosity, is your Quest pad one of the older ones made from PVC? [/B]

It is one of the newer ones, I think. I've attached a photo of my (now defunct ) MK109 Stingray on it. It does have the rod diameter getting smaller in the upper section.

As I say, I've got to upgrade for my Drake. My wages clear on Monday, so I'll be getting one then, and we shall see!

 

[Ryan S.]

I have flown my fat boy many times and have never had it arc like you said but I have seen many fly that way

About Estes nozzles deteriorating; I think that, that may have something to ddo with them absorbing moisture. This is only theory but I think that the clay could soften just from moisture in the air. The reason I say this is I left a burnt motor with the old clay on my basment floor where there is alot of humidity. I forgot about it but then when I was cleaning I found it and the I could actually form the clay from the nozzle. When I first saw the clay I didnt even recognize it.

so maybe if the old motors are kept in levels of high humidity (or even moderate) for extended periods of time the clay may soften

 

[saxophone]

What size parachute comes with a stock Fat Boy?

 

[GoBang]

Originally posted by saxophone
What size parachute comes with a stock Fat Boy?

18". I've always thought that was overkill though unless you're going for duration. 12" has worked well enough for me.

 

[wyldbill]

Originally posted by GoBang
18". I've always thought that was overkill though unless you're going for duration.

...or you fly at high altitude where the air is thinner and things come down a lot faster. Estes is "in" Penrose, CO....

FWIW,
-bill
(also in CO....)