Does anyone know how to get an original Estes 23" Bomarc to fly correctly?

[tbsb9595]

When I launch it with a C or D20 engine it flys straight up and then turns horizontal on its back and flys like a plane?
Does anyone know how to fix this? Thanks, Tom

 

[dpower]

Nose weight. My 657 clone has about 2.5oz, flies very straight on C11 and D12 motors. With 18mm Q-Jets like the C12, D16, C18, or D20, less would do.

 

[Back_at_it]

As Dpower stated. It needs nose weight. I don’t remember how much I had in mine back in the day but it was ALOT!! certainly more than 2oz

 

[tbsb9595]

Thanks for your Help! My nose cone weighs approx 1.75oz with the weight I added per directions. My Bomarc is the old 23" Estes Model, Is your the same one? Did yours fly horizontal also until you got enough weight in the nose?

 

[KenECoyote]

This may be helpful. :
https://www.rocketreviews.com/estes-bomarc-0657-andy-hobbs.html
Also try a swing test with the motor installed (do a search here or on YouTube).

 

[86mustang408w]

Thanks for your Help! My nose cone weighs approx 1.75oz with the weight I added per directions. My Bomarc is the old 23" Estes Model, Is your the same one? Did yours fly horizontal also until you got enough weight in the nose?

Most of these model rockets only fly as you know for a few seconds if that compared to one that stabilizes over minutes. When you add a bigger motor and more weight it changes the CG, its also changes the CP drastically during flight. At the point when it loses thrust, it becomes unstable because the CG has changed from the fin area to elsewhere. As your rocket burns propellant, its going faster and getting lighter in the aft end as well. All the sudden now that weight, is gone. Right after thrust.

A lot of shorter and stubby rockets are like that too. My Baby Bertha does the same thing from A to 29mm motors, it will be fine until a certain point, then literally goes horizontal. But as the CP changes during the flight, you'll get this if you don't have it correct. Each motor you'll need to add or remove NC weight to keep the CP correct, you could also add something in the form of a base drag on the fins to stabilize it after losing thrust as well. Or, made it a bit heavier(airframe) overall so when it coasts after thrust, the CP stays around the fin area, here it pretty much disappears, or goes below the fins or above them. Rendering them pretty much useless.




I may be wrong here too.

 

[David Schwantz]

I am sorry but the CP does NOT change in flight, until near mach. It does NOT change with a bigger motor. The CG will change. You do not add or remove weight to change the CP, it changes the CG of a rocket. When motor burns out, the CP does not move forward, the CG does. The reason your rocket flips at burnout is due to less airflow over the fins because of less thrust. Try throwing a dart with no metal tip. You have removed so much weight now the fin section will not fly straight. Add the metal tip back on and now it will fly. The rocket needs more nose weight.

 

[dpower]

Thanks for your Help! My nose cone weighs approx 1.75oz with the weight I added per directions. My Bomarc is the old 23" Estes Model, Is your the same one? Did yours fly horizontal also until you got enough weight in the nose?

You're welcome. Estes had 2 versions, glide recovery (654) and later, parachute recovery (657). My build is a clone of the 657, using plans from JimZ, the only changes were a 24mm motor mount, and a hollow balsa nose cone from Balsa Machining. The total NC weight with BBs, epoxy, and screw-eye is 2.8oz. I had heard the original was a bit dicey on the C6-3, and Q-Jets weren't available, so went with 24mm and extra nose weight. It's always flown perfectly vertical on C11 and D12 motors.

You mention the D20 was this a Q-Jet? And which C motor did you fly?

 

[Fishhead]

Uh, no.

The jacket looks so horrible because it was the only thing I had to fight the fire with. I wound up with a lung issue from smoke inhalation and almost quit the hobby.

 

[BigMacDaddy]

I had always heard that people struggled to get the Estes Bomarc to fly straight. I was surprised since my Bomarc (my own design) flew so straight.



I wonder if part of the difference is that the wings on my design are down on the body tube (like in the real thing) instead of on top of the tube like they are in many designs. I did also load 1oz in nose.

 

[Alan15578]

When I launch it with a C or D20 engine it flys straight up and then turns horizontal on its back and flys like a plane?
Does anyone know how to fix this? Thanks, Tom

I still have my original and it flew well. The nose cone is very thin and fragile and I do not fly it any more. There is a rear ejection pod that has a hook that holds the elevator flat for boost, and allows it to pop up after ejection for glide. You may not be getting the elevator held down when you prep your model.

 

[Back_at_it]

Thanks for your Help! My nose cone weighs approx 1.75oz with the weight I added per directions. My Bomarc is the old 23" Estes Model, Is your the same one? Did yours fly horizontal also until you got enough weight in the nose?

I believe mine was the 23” version. It was definitely Estes. Mine wouldn’t fly horizontal but it was certainly unstable. I swung tested mine and added weight until the swing test worked but it wasn’t enough. I ended up adding more.

Unfortunately it’s been so long I can’t give you exact numbers but I want to say I had around 2.5ish in the cone give or take.