I bought a Quest X-15 rocket kit and measured the body tube length. It measured 14" long.
The instructions, both in the kit and online, read the BT length 11" long.
Do I cut the tube or leave it alone?
It probably does not matter, than again it might!

Daniel

I know the BT for the X-15 was too short in the past at 11". Either that, or the strakes that run the length of the tube were too long. Considering the marginal stabilty, I'm guessing the tube was too short. I remember having to trim the strakes on mine for a proper fit. I've never heard of anyone getting a tube that was longer, but this may be a recent change to the kit. As it was, the kit was marginally stable and needed about 1/2 ounce of weight in the nose to get a predictable flight. Ironically, Quest motors exploited this. Rather than add weight to get the CG where it needs to be, I wonder if Quest decided to lengthen the model to compensate for the instability?

I say, it's your choice what you want to do here.

Personally, I would cut the tube to match the length of the strakes. If I remember correctly, the tube length should be about 11 and 1/4 inches (or maybe 11 and 1/2...it's been a while ). But again, it's a good idea to add a little nose weight if you go this route. This will also help retain the scale like appearance. With this model being sport scale, with an emphasis on "sport", it may not matter very much you. It just depends on how picky you are. You could use the whole 14 inches of tube you were given and let it ride that way too. In that scenario, I would put the strakes flush with rear end of the tube.

Here is mine with the 11" tube and the strakes trimmed down to match.

Did you mean to say exposed?

The X-15 is in my to-build pile. I seem to recall some kind of discussion about the fin marking guide being printed wrong in early versions of the kit; I wish I had paid more attention then.


Bill

You could always modify it to the delta wing variant (proposed). It was to have a longer fuse anyway. Let me see if I can find a picture . . . .

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The only motor I could get a stable flight from before adding nose weight was an Estes C6. I flew multiple flights with Estes B6 and Quest C6 and all flights on those ended up in loop d' loops! Only light wind, if any, on the days it was flown. If a Estes B6 was unstable, then there stood a good chance the Quest B6 would be, so I didn't even try. I think the higher thrust of the Estes C6 was enough to overcome any stability issues. Someone I fly with also encountered the same thing with his, and after talking, I discovered he added nose weight to his too. Neither of us over-build and are experienced rocketeers, so I know build technique and finish weight wasn't the issue here.

I agree with Foose... the BT on mine is 11 inches. If you have longer strakes, cut the tube to match the strakes. It will fly better. Balance it with a B6 (add weight to the NC). It will fly well. I like mine. I even still like it after trapsing through the Western PA sticker patch to get it at NARAM 51....

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Jerry Little
TRA #11767
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I contacted Quest about this anomally several months ago. The BT was intentionally lengthened to 14" recently to increase stability. To keep the the scale though and to make the strakes match, I cut the BT down to the same length as the strakes. After contacting Quest, they sent me TWO FREE X-15 KITS just for bringing it to their attention!

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I built a Quest X15 three or four years ago. All flights on Estes C6-5. First simply did a tight end-over-end and flopped to the ground with no damage. Taped three pennies to the shock cord at the attachment point and second flight was good. Third flight was wobbly and coney. Switched pennies for a 1/3 oz clay in the nose cone. Fourth flight went straight for about 30 ft, flipped a couple times, then headed straight for an erosion fence... on contact, the body went through the fence, the fence just simply stripped all the balsa parts away, and the ejection charge started the plastic part of the erosion fence to burning! Man! Was that an exciting flight or what!

So when another club member showed up with a Quest X15 a couple of years ago, I warned him about the problem. He flew it anyway, result was same as my flight #1. We talked about it some more and he went back and put in about 1/2 oz of clay in the nose. Good flight, but he added another 1/4oz for good measure, and his X15 has flown straight ever since.

Today at our launch, a third member comes up with an X15 (appeared to be an 11" tube) and asks me what I think, I refer him straight to the first guy, who gave him the clay needed and showed him how to install it. Both of the flights were good.

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Roy
nar12605

Yep, 1/2 oz. does the trick. That's what I ended up putting in mine. Curious why Quest opted to lengthen the tube to 14 inches instead of adding clay to the kit, but either way does the trick. I guess that solves the strake issue as well.

Main reason? You don't have to change the instructions (assuming they didn't say to glue the strakes on flush with the *front* of the tube!), and you don't significantly increase the weight of the rocket.

This would be called the "Cherokee D Solution." The first Cherokee D rockets, whose body tubes were 16" or so, occasionally "overreacted" to wind. Like mine, that only lasted one flight, as it got to about 50ft, suddenly turned nearly parallel to the ground and headed into some deep woods about 700 ft away.

Estes solved the problem by shipping future kits with full 18" tubes. Don't know if the change from balsa to plastic nose cones had any effect as well.

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nar12605