What's with these LOC fins?

[Buckeye]

A LOC "Park Flyer" Magnum came my way. I am not a fan of the name (there is a whole thread on that), and I am gonna build it for HPR, especially the new H13.

What is up with the fins? They look very small, and what is the purpose of the extended root tab? It does nothing. The only thing I can think of is that LOC has only one pattern of body tube fin slots for the entire Park Flyer series, and the tab is to just fill in the excess slot opening on some variants. I'd rather have a bigger fin that uses the entire slot length.

The nose cone weighs a frickin' ton, so that may help the CG/CP relationship of the puny fins. I'll work it up in RockSim and see what the stability looks like.

 

[dr wogz]

That is quite likely the reason. Stocking less parts = $$ saved. Using the same parts on multiple designs / models also helps reduce overall cost. (increased part ordered, = more of a quantity discount)

the fins are sized to be 'downscaled' of the original 5.5" original.

(and no, not really a fan of their 'park flyer' series)

 

[Scott_650]

Just a suggestion but if you’re going to build a 29mm powered BT60 sized rocket why not take a look at the fiberglass kits from Mach 1. No worry about the rocket holding up over big motors but still flyable on F motors. I do like the concept behind LOC’s “downscale” kits - kinda nifty having smaller versions of your bigger HPR rockets.

 

[crossfire]

A LOC "Park Flyer" Magnum came my way. I am not a fan of the name (there is a whole thread on that), and I am gonna build it for HPR, especially the new H13.

What is up with the fins? They look very small, and what is the purpose of the extended root tab? It does nothing. The only thing I can think of is that LOC has only one pattern of body tube fin slots for the entire Park Flyer series, and the tab is to just fill in the excess slot opening on some variants. I'd rather have a bigger fin that uses the entire slot length.

The nose cone weighs a frickin' ton, so that may help the CG/CP relationship of the puny fins. I'll work it up in RockSim and see what the stability looks like.

View attachment 446525

Ask LOC

 

[heada]

I have several of the park flyers and all the tubes have nearly the same fin slot openings, regardless of fin size. They then make up the size difference with the tabs on the smaller fins.

 

[jqavins]

I got one for Secret Santa 2019. I also wondered briefly about the tab extensions, but honestly didn't give it much thought. I never gave any thought to the fin size either; they look fine to me and Rocksim agrees.

 

[DMehalko]

One tube with one laser settings to support a multitude of variants

 

[Tractionengines]

Two notes: Yes, most kits use same sloted body tubes 2 versions 3 or 4 fin slots. (1.6" dia. is 17" long) then they add an adjustable length of payload section to give the correct overall length. This keeps the number of parts in inventory down. Also packaging sizes. (Fins with longer tabs take up a lot less space than a bunch of sizes of body tubes)
As for nose cones. The black 1.6" is heavy. They have a new BLUE 1.6" nosecone that is lighter. (In the nosecone section of parts. You can get either.)

 

[kuririn]

If you think that's bad take a look at the difference between the fin root length and the slot length of the Madcow 2.6" Lil Squat.

Nothing that a little sanding and filler can't fix.

 

[tOD]

A LOC "Park Flyer" Magnum came my way. I am not a fan of the name (there is a whole thread on that), and I am gonna build it for HPR, especially the new H13.

What is up with the fins? They look very small, and what is the purpose of the extended root tab? It does nothing. The only thing I can think of is that LOC has only one pattern of body tube fin slots for the entire Park Flyer series, and the tab is to just fill in the excess slot opening on some variants. I'd rather have a bigger fin that uses the entire slot length.

The nose cone weighs a frickin' ton, so that may help the CG/CP relationship of the puny fins. I'll work it up in RockSim and see what the stability looks like.

View attachment 446525

I had a similar experience a while back with a Park Flyer EZE, the fins just looked too small, and had those long tabs on them to fill the slots in the body tube. Turns out that the wrong fins had been packed in the kit. If you can you may want to check the dimensions against the Rocksim file. Eventually LOC replaced the whole kit. I looked at the file and there are no "tabs".

 

[jqavins]

I got one for Secret Santa 2019. I also wondered briefly about the tab extensions, but honestly didn't give it much thought. I never gave any thought to the fin size either; they look fine to me and Rocksim agrees.

I had a similar experience a while back with a Park Flyer EZE, the fins just looked too small, and had those long tabs on them to fill the slots in the body tube. Turns out that the wrong fins had been packed in the kit. If you can you may want to check the dimensions against the Rocksim file. Eventually LOC replaced the whole kit. I looked at the file and there are no "tabs".

They look like the ones I got.

 

[dr wogz]

Madcow Skipper too.. small fin, long tab.. (mine at least had..)

 

[Donnager]

I had a similar experience a while back with a Park Flyer EZE, the fins just looked too small, and had those long tabs on them to fill the slots in the body tube. Turns out that the wrong fins had been packed in the kit. If you can you may want to check the dimensions against the Rocksim file. Eventually LOC replaced the whole kit. I looked at the file and there are no "tabs".

I checked the balance with my 1.6 LOC EZE with an empty H-115 motor (3.2 oz) and I left the nut off the retainer, and it looked OK. I tried to fly it with an F-67 (2.85 oz) with the retainer on, and apparently the balance was much closer than I thought. It flew unstable. The length of the dead motor and the lack of the nut were adequate to make the difference. I'd be careful flying larger motors in these without a GOOD balance check, with the proper weight motor loaded. I've only had two unstable rockets, and this one surprised me.

I've since added a couple ounces of putty to the EZE and a 1.6 park magnum beyond what I thought.

 

[Jay Rairigh]

I'd rather have a bigger fin that uses the entire slot length.

Well...I guess it would not be a LOC Magnum then.

 

[DMehalko]

I checked the balance with my 1.6 LOC EZE with an empty H-115 motor (3.2 oz) and I left the nut off the retainer, and it looked OK. I tried to fly it with an F-67 (2.85 oz) with the retainer on, and apparently the balance was much closer than I thought. It flew unstable. The length of the dead motor and the lack of the nut were adequate to make the difference. I'd be careful flying larger motors in these without a GOOD balance check, with the proper weight motor loaded. I've only had two unstable rockets, and this one surprised me.

I've since added a couple ounces of putty to the EZE and a 1.6 park magnum beyond what I thought.

Did you ever refly the EZE? I agree the fins seem tiny

 

[Donnager]

Did you ever refly the EZE? I agree the fins seem tiny

Yes. They are, and I did. I sent it on an E-20 or E-30 from memory, and it flew well with the added nose weight. I don't recall off the top of my head how much, but If you'd like to know I can weigh the nose when I get a chance. I'm sure some of my issue is using a metal retainer that shifted the weight back more than I thought. I only posted to mention that the small fins don't give you a lot of margin. It's best to use the actual motor you will be flying, completely installed with retainer, and recovery.

I'd still like to fly it on a large F, but I really haven't had an opportunity.

 

[Donnager]

Did you ever refly the EZE? I agree the fins seem tiny

I checked the rocket. My nose cone with weight and paint is 4.2 oz.