Estes Pathfinder Stability

[jdud]

After building my Estes Pathfinder clone, I performed a swing test and it flew backwards. EMRR's CP library had the CP listed between 36 and 37" from nose and my CG was at 31" with an Estes E9-6 loaded. It was built with TTW basswood fins (for those E and F flights), so I know it is a bit tail-heavy.

Does this pose a problem? The CP and CG seem to be in their appropriate spots. I posted a picture below (my first TRF picture) --still have to apply the decals.

 

[Luv2launch]

Since its such a long rocket a swing test might not work on it I built a tube finned rocket out of a mean machine that was about half the length of a normal mean machine and it wouldn't swing stable even though I made a version of it in rocksim.It flys fine on D12-7's so far thats all I have tried in it.

 

[DAllen]

After building my Estes Pathfinder clone, I performed a swing test and it flew backwards. EMRR's CP library had the CP listed between 36 and 37" from nose and my CG was at 31" with an Estes E9-6 loaded. It was built with TTW basswood fins (for those E and F flights), so I know it is a bit tail-heavy.

Does this pose a problem? The CP and CG seem to be in their appropriate spots. I posted a picture below (my first TRF picture) --still have to apply the decals.

It's tough to do a swing test on a rocket that size. You may not be achieving high enough velocity with the swing test to accurately determine stability. Have you checked the stability versus the card-board cut-out method?

Anyone have this rocket in Rocksim? I'd hate to have you needlessly add a bunch of noseweight and sacrifice performance. Just by the utter looks of it I'd say a rocket with that configuration ought to be plenty stable.

-DAllen

 

[Buzzard]

I have an Estes Pathfinder that is done up in Stars and Stripes (ref: North Coast Rocketry Star Spangled G Bird). Many, many flights on C11s. D12-5s, and E9-6. The basswood fins will not effect the stability as those designs are over-stable to begin with.
I have being in the hobby for 41 years and the string test is a comforting exercise to prove the hobby is safe, but is notorious for being stable either way. A design that wanders between fore and aft is suspect.
Good luck and post pictures.

Chas

 

[snaquin]

You're rocket looks great.

As Chas mentioned it's an over-stable design. I have flown the stock model less the 24mm mount using a G25 without adding any weight. It was a great demo rocket using that motor and streamer recovery at our large flying field.

You'll have no problems using E or F motors in this rocket.

.

 

[jdud]

Thanks, I was also thinking that the length was causing the backwards flight. I'm glad to hear others have put this bird up on E's and G's. Its just begging for an F24 or an E18. I'll post another picture once I get time to put the decals on.

 

[RoyAtl]

After building my Estes Pathfinder clone, I performed a swing test and it flew backwards. EMRR's CP library had the CP listed between 36 and 37" from nose and my CG was at 31" with an Estes E9-6 loaded. It was built with TTW basswood fins (for those E and F flights), so I know it is a bit tail-heavy.

Does this pose a problem? The CP and CG seem to be in their appropriate spots. I posted a picture below (my first TRF picture) --still have to apply the decals.

Swing tests are kinda tricky on larger, long rockets, because the relatively short radius of the test and the long moment of the nose means that the angle of attack on the nose is much more severe than it will probably ever experience in flight, and the nose will experience such drag that it turns the rocket around!

There's a lot more to it than that, of course, but that is the gist of the problem.

 

[MarkII]

I can't explan the physics behind it (because I don't really know them), but long, thin rockets like the Estes Pathfinder are naturally overstable.

BTW, I really like the Pathfinder, too, and it has been on my "to be cloned" list for quite awhile now. (Note to self: better get going on that. )

Mark \\.

 

[rocketron1948]

I have flown my Pathfinder many times using the standard 24 mm. engine mount with no problems. It flies very straight with no stability issues. It is a nice kit.

Rocketron
NAR # 31475
My Webpage: https://www.angelfire.com/space/r_watkins/homepage.html

 

[kelltym88]

I have an original Pathfinder that I have flown many times w/o any problems. In fact I found a booster from another rocket and used it to stage my Pathfinder, now that was cool. Your upgrades should be just fine. Nice lookin bird.

 

[NAR29996]

I've flown mine on up to F39 reloads with no problems. 'Course, I built it before Estes E's came out so I've never used them in this model.

Regards,

Bob B

 

[rokitflite]

I don't know the full story, but in the late 90s Estes must have turned up about 40-50 cases of Pathfinders and Explorer Aquarius OR discovered enough parts to make that many, kitted and sold them to Horizon Hobby "under the rocketeer radar". I flipped when one of each just showed up in our stores. When I figured out where they came from I asked our sales rep how many they had and she said she was not allowed to say, but they had "plenty"... I asked the price (wholesale) $3.25 each for the Pathfinder, $6.50 each for the Aquarius... I nearly fainted. Needless to say I got dozens of each. I never did get the story of where they came from (it was several years after they had been discontinued in the catalog). I always liked the Pathfinder... And the blow molded nose cone/transition combo it came with.

 

[jdud]

I asked the price (wholesale) $3.25 each for the Pathfinder, $6.50 each for the Aquarius... I nearly fainted. Needless to say I got dozens of each.

Wow, what great luck. The pathfinder was available during my younger days of rocketeering, but I never built one...until now. I do have an old Explorer Aquarius that I would like to rebuild. I've been saving the center out of all of my 18mm centering rings just for that purpose.

The 1st coat of Futures is drying on my Pathfinder right now. I'll try to post a final picture when I am done.

 

[jdud]

I worried for nothing. Launch was straight as an arrow today on a D12. This bird will likely scream on an E18...or maybe an F24. Forgot to take my camera to the launch site, but I did snap a shot of the finished rocket at home.

 

[rokitflite]

That is a GREAT looking model!!! Please don't lose it with one of those bigger motors!

 

[Handeman]

That is a GREAT looking model!!! Please don't lose it with one of those bigger motors!

What he said, but definitely fly the bigger motors!

 

[MarkII]

Beautiful rocket! You did a GREAT job! I'd love to see that one fly!

Mark \\.