Changing motor from Estes "D" to Aerotech "F"

[Martin_G]

Hi Everyone,


I'm considering buying the Estes "Saturn V" kit but I would like to get more height than the advertised 150 ft. using an Estes "D" motor.

The motor I had thought about using is the Aerotech F20-4W . Would this be a good substitute motor to use or would it cause problems with the rocket itself (structural integrity)?

The other idea I had was to use a 3 motor cluster (Estes "D") as an option.

I do have experience building & flying smaller single stage Estes kits including the Cherokee "D" and 2 stage rockets. The Saturn V will be the largest one to date.



Any ideas,suggestions or recommendations are welcomed!



Thanks,

Martin

[Pantherjon]

It would certainly get it going pretty quick! And I think that maybe the 7 second delay would be better..Personally I would go with an F24 in the 24mm case..

[Martin_G]

I tried downloading "rocksim" software from Apogee to see what an estimated altitude might be but apparently my computer doesn't like the program!

If I was to use an F-24 motor what kind of altitude could I expect?

Ideally, I would like to get the Saturn V up to around 600 ft. or close to it. Do you think this is possible? A little higher is ok too, but the minimum I'm looking to get is 550-600 ft.


BTW, the F20-4W single use motor has the same thrust as the F24 (40.9)but it burns longer (2.80 vs. 2.13). The Estes "D" motor by comparison is rated at 29.7 thrust and a 1.65 burn time.



HTH,

Martin

[RoyAtl]

The F24-4 should work really well in an unmodified Saturn V. I would be wary of windy days, however. An F39-6 might be a better choice then. If the Saturn is built well and normally, it should be able to take the higher thrusts.

To use the F20, you'd have to modify it for 29mm, which might be a decent option.

-----------------

In 1970, one of our club's members modified a Centuri Saturn V to use an FSI F100-7 motor (which was really a 40-50ns motor with closer to a 50 newton avg thrust) and he flew it pretty regularly. The main structural difference between that model and the current Estes model is the Centuri used five hard balsa centering rings, four of them 1/8" thick, while the rear was 3/16", and the core tube was a 1.6" tube (for three C motors) so it was simple to install the 28mm mount.

The Estes kit uses just three cardboard centering rings, and its core tube is a 1" tube.

If you go for higher thrust motors, I would add three gusset plate braces to the end centering rings.

[georgegassaway]

Take note that any weight you add in the back, you have to balance out by adding noseweight, or it will go unstable.

It would be a lot simpler to just build it stock and fly it on an Aerotech E15-4 (same size as a D12). It would fly great on an E15-4.

Since you mentioned an F20, well, that has 63 N-sec. A heavier motor, and the increased mass of a 29mm mount, and then the noseweight to counterbalance that added weight in the back, a significantly heavier rocket overall. So, it may be that just building it stock and flying on an E15 would fly it about 75% as high as a modified one with an F20 .

EDIT - I forgot about 24mm reloads. You could use an F24 reload, as Roy suggested. That is 50 N-sec. Now, a reload casing weighs a bit more than a D12 casing, so you would need to add a little bit of noseweight, but not nearly as much for a 29mm mount and F20. I do NOT think that the original centering rings would have to be reinforced, just simply glued properly to begin with (Titebond with adequate fillets when gluing the motor tube to the rings. No epoxy needed).

- George Gassaway

[[POW]Eagle159]

WHATEVER ENGINE YOU GO WITH ADD NOSE WEIGHT......

I launched mine with AT E20-4w...BAD, flipped twice, bounced off a a tree branch, hit the ground flat than ejection, nose cone blew off 15' feet!

All is repaired and added nose weight, will launch soon again.

I think the E20 will get up there 400' though.

[Martin_G]

Thanks for your suggestion on the choice of motor to use.

I recall years ago that when you changed things around, especially when you wanted to use a higher thrust motor, 85% or more of the time you usually had to modify parts of your rocket whether it was the motor mount, CG or making the fins thicker.

Since I've not flown or built a rocket like the Estes Saturn V, then right off the bat decide to modify for a much higher flight.......then I should do it right!

Over the years I've learned that regardless what you're working on, either "Do it right" the first time or don't do it!

And...if you're in uncharted territory such as wanting or needing to modify something like a rocket such as the Estes Saturn V, don't be afraid to ask questions & try to find someone with experience doing this!


As an option, would I be better off using a cluster of 3 to 4 motors unstead of a single one? Ideally,I would like the rocket to have as realistic a "lift-off" as is possible.





Thanks,

Martin

[[POW]Eagle159]

Thanks for your suggestion on the choice of motor to use.

I recall years ago that when you changed things around, especially when you wanted to use a higher thrust motor, 85% or more of the time you usually had to modify parts of your rocket whether it was the motor mount, CG or making the fins thicker.

Since I've not flown or built a rocket like the Estes Saturn V, then right off the bat decide to modify for a much higher flight.......then I should do it right!

Over the years I've learned that regardless what you're working on, either "Do it right" the first time or don't do it!

And...if you're in uncharted territory such as wanting or needing to modify something like a rocket such as the Estes Saturn V, don't be afraid to ask questions & try to find someone with experience doing this!


As an option, would I be better off using a cluster of 3 to 4 motors unstead of a single one? Ideally,I would like the rocket to have as realistic a "lift-off" as is possible.





Thanks,

Martin

The only problem is 3-5 engine will be ALOT heavier and with their mounts, ALSO if something happens where one or two doesn't light...lots of work and money crashes into the ground.

I was lucky mine didn't get totaled...

[Martin_G]

Hi Eagle,


Motor clusters have their own unique set of problems with one or more motors not igniting when they should or not at all!

Years ago a buddy of mine who got into rockets after he saw how much fun I was having, flew a couple of Estes single motor kits then he went right to using clusters on larger kits.

IIRC, the failure rate (to ignite) approached 35 to 40%. Later on as different ignitors became available the problem was resolved to a degree but ignition was never 100%.

One day all flights might work just fine, but then the next time he would fly the "problem" would come back again! After working with clusters for awhile he finally gave up on them and went into mult-istage rockets.



When do you expect to fly your Saturn V again with the E20-4W ? I would like to hear about how your flight turns out!



Thanks,

Martin

[[POW]Eagle159]

I will hopefully launch in a few weeks with my Saturn V. I will post about it and maybe a video..

I WILL defiantly launch before Christmas, maybe even twice.

[Martin_G]

Hi Eagle,


What kind of mods if any did you do on the Estes Saturn V ?


I have a habit of modding things like cars & motorcycles, (and an ocassional rocket). LOL! In any event, Safety is #1 !

With some rockets, I might consider using thin ply-wood on motor mounts & bulkheads,etc instead of paper unless the rocket is only going to use a small engine or you're trying to build a fairly light rocket.




Martin

[Grendel]

I tried downloading "rocksim" software from Apogee to see what an estimated altitude might be but apparently my computer doesn't like the program!

Try Openrocket.

[[POW]Eagle159]

Hello Martin,

About my Estes Saturn V, it is all stock. I followed the instructions all the way, It actually is a very easy build to me, only took one week from start to finish. That is though all day every day because it was summer break and nothing to do. The whole build is nice and though out, the only thing I changed was using epoxy to glue the ''wraps'' to the body and the fins and fairings to the body.
When I launched mine on a D12 it was VERY low, next flight was an E20-4 with no mods, it left the rod, flew kinda good until like 200'(already higher than the D12) then it looped twice hit a tree than the ground than ejection...When I looked at the bottom of the nose I saw the one circle base thing it was about to fall off and dented inwards from the ejection charge.
here are some good links :

cheapest place to buy(where I got mine)
http://www.hobbylinc.com/htm/est/est2157.htm

at estes site (pics of parts layout)
http://www.estesrockets.com/rockets/...02157-saturn-v

Instructions(takes a minute to load)
http://www.estesrockets.com/media/in...7_SATURN_V.pdf


I love the estes Saturn V I think it is the best kit out there ,not too big or small, or complicated.

What ever you do(engine or major mods) get the Cg to 18'' from the bottom of the rocket.
I had to add a huge marble like 1.5 in. diameter. than epoxied it into the plastic nose cone.

I think I covered every thing... if not ask!!!