Arapahoe E

I'm coming somewhat close to being finished with my clone of the Thrustline Arapahoe E, so I figured I'd go ahead and ask a few questions.
First, for those who fly with altimeters, are you getting extremely high altitudes out of your birds? I'm sure the virtual OR rocket it a lot lighter than my actual finished product will be, but it's saying that the Arapahoe E will fly over 1300 feet on an E9-- this seems pretty high to me, but I guess I'm could just be used to heavier, more draggy rockets.
Second, is the BT really 17" long? That's what the .rkt file I downloaded says, but it seems like it would make for sense to just use an 18" tube. But, I guess not everyone is as lazy as I am.
Also, has anyone added motor retention to one of these birds? I'll be flying it mostly on 24/40 reloads, and I'm nervous about losing my case. No matter what the old-timers say, I'm just not sure I can trust a $0.01 cent piece of tape with a $27 dollar case. It seems like maybe you could glue the motor tube into the boat tail with a little but sticking out the end, and add a screw-on retention system...? You could compensate for the modified motor placement with a little nose weight.
And lastly... what color should I paint the fins and nose cone? My choices are metallic blue, sunrise red, or royal purple. :grin:

Go to the Arapahoe E Gallery and look at some of the various paint jobs. Mine is in there also. Flew great on a D motor. There's really no need to go with reloadables unless that's just a preference. The model has superb stability.

Gary Byrum said:

Go to the Arapahoe E Gallery and look at some of the various paint jobs. Mine is in there also. Flew great on a D motor. There's really no need to go with reloadables unless that's just a preference. The model has superb stability.

Click to expand...

Thanks for the link . I'm sure I've seen it before, but I'd forgotten about. I like the purple, and I have the purple so that would be the cheaper option... but I think I'm just going to go out and buy some regular blue paint and do the original scheme. I've spent so much money on rockets it hardly matters any more! :eyepop:
As for motors: sure, I'll bet it flies great on D motors. In fact, I'll probably send it up on a D at first, but then it's E18's to 1800 ft with streamer recovery. Heck, it sims to ~2140ft on an F39-9T, and I do have a few of those laying around.... :wink: I really like AP motors!
As for the BT, I feel dumb for not checking the OR file first-- I didn't have any 18" BT-60's since I'm using the 15" tubes from Hobbylinc, so I coupled a 3" section from a shorter spare tube onto the 15" tube, thinking at the airframe was 18" long. Now it looks like I may have to trim the tube down after I've already spliced the two together. :bangpan: Oh well, it's not that difficult.

Rocketbuilder said:

Thanks for the link . As for the BT, I feel dumb for not checking the OR file first-- I didn't have any 18" BT-60's since I'm using the 15" tubes from Hobbylinc, so I coupled a 3" section from a shorter spare tube onto the 15" tube, thinking at the airframe was 18" long. Now it looks like I may have to trim the tube down after I've already spliced the two together. :bangpan: Oh well, it's not that difficult.

Click to expand...

Bryan at BRS HOBBIES sells 18" tubes at 70's prices. Just a word up. The purple I used was Valspar and it turned out just fine. Are you buying a tail cone or are you turning your own? I turned my own but I have a lathe....or two. Here's the link to BRS HOBBIES. He has killer prices on a great many things.

I got the nose cone and tail cone from Semroc-- found the part numbers in an old TRF thread. I wish I could turn my own balsa parts. :sigh:

Rocketbuilder said:

I got the nose cone and tail cone from Semroc-- found the part numbers in an old TRF thread. I wish I could turn my own balsa parts. :sigh:

Click to expand...

Turning your own parts can seem like a chore at times but once you learn how to do it, it changes into gratification. And it a heck of a lot cheaper!

Gary Byrum said:

And it a heck of a lot cheaper!

Click to expand...

In the long run, sure, but balsa's still not cheap, and there's no way I can afford a lathe!
So I've been thinking about the motor retention thing, and I came up with an idea that just might work. I'm wondering if it's possible to create two holes (one of either side of the motor tube, right up against it) in the balsa tail cone, then put two metal tubes with threads on the insides (not sure what to call them) in the holes, then drill two holes in a washer. You could then thread bolts through the washer and into the metal tubes, giving you a plate retention system. Possible, or crazy?

Possible but you are really thinking overkill at this point. You might even damage your motor casings. ( if I read this right ) I'm a bit green on some of the reloadable motor retention methods but I keep hearing that taping them is still a reliable method. I'm still learning about these kinds of motors so I'll suggest you letting someone else weigh in.

I'm not sure how that could damage the casing, but you're definitely right about overkill. I think I may go with the $0.01 piece of tape. I figure, if I try what I just described, there's a very high probability of destroying ~$7 my tail cone, but with the tape there's a small chance of losing a $27 case. So, tape it is. Of course my own laziness has nothing to do with this.