#11
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I thought of the same article. While the article is basically how to "hot rod" a HoJo for HPR, the one really good take-away from the article that can be ported to LPR are the treatment of the fins. My suggestion is that for LPR applications, you could do a 2 sheet layup of fiberglass (or even carbon fiber if you have the money) and get plenty of fin strength. The fins would still be light, and yet have exactly the same diamond profile found in the kit. Might be a little pricey, but at the end of the day you really wouldn't worry about how the fins will hold up. Greg |
#12
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Again, thanks for all the advice guys. The RP article is cool, but a bit overkill
OK, next dumb question. If I want to beef up the motor tube with a stronger tube, any suggestions on which one and where to get it? Thanks! |
#13
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The T50H-34 from BMS is a heavy wall 24mm tube. They also sell a T50MF-34 which is foil lined.
http://www.balsamachining.com/bms_2009.pdf
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Don NAR 53455 "Carpe Diem" |
#14
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I did a few upgrades to my MHJ:
1) Aerotech 2.6" tubing - about twice the thickness of stock Estes tubing 2) Bass wood stringers in the fins. I like Gordon's idea of using a styrene sheet also but mine make the fins "through the wall" 3) 29mm mount 4) V8 can engine baffle 5) Nylon chute and zipper resistant surgical tubing It can just barely fly on a D-12-3 and goes probably goes to about 400-500 feet on a F reload. Yitah |
#15
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Careful with the foil-lined tubes. Estes 24mm motors (D's and E's) can be a *really* tight fit. S. |
#16
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How true! Also, the foil peels out fairly easily, which kinda negates its advantage. Allen |
#17
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But, the extra thick wall of the tube is nice even without the foil. That's why I've started using just the extra thick 24mm tubes that are available from LOC, etc. I find that soaking some CA into the tube, then sanding it smooth, makes for a surface more durable than the foil. The only caveat to these tubes is you need to get the centering rings with extra large holes (eg, CR-50-60mf), or you have to sand out the regular BT-50 sized rings. Doug .
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YORF member #11 |
#18
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ST-9 tubing (Semroc) is also the same ID as BT-50 but with substantially thicker walls. Centering rings would need to be reworked a bit as Doug notes just above....
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Bernard Cawley NAR 89040 L1 - Life Member SAM 0061 AMA 42160 KG7AIE |
#19
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Yeah, and I've had the foil just burn/melt off, which again kinda negates the purpose. I'm going back to using the plain old HD motor tubes. S |
#20
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I have been guilty of either smearing 30 min epoxy all around the upper part of the engine tube and on the inside of the lower part of the engine tube. This seems to give a nice protective layer that holds up to ejection charges and the wear and tear at the bottom. However, the usual engine fit can problematic when I do this.
More recently, I have had good results using thin CA in these areas. I have to sand down the inside a little if the engine fit is a little too snug, but the tube is remarkably strengthened and protected this way. I don't think as much weight is gained using CA over epoxy, but I have not checked this properly. Greg's suggestion of carbon fiber fabric and Sandman's suggestion of a central plastic sheet core (redundant?) are perfect if you want to keep your engine selection up through 'E' and get her back in one piece. I'd use both ways together. Greater than an E (or LOW F), use Thru-the-Wall. Still use the suggested techniques above, but make your core with the proper tabs. Heck, do this and you'll always be covered, regardless of what engine you choose (24mm). Got one and plan to do mine this way now. Eventually..... Hope this helps, Allen |
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