HP-24 Project

I spent the weekend of 19 November giving a talk at the annual PASCO seminar on the HP-24 project, and the prior weekend or two working on tooling for the aft fuselage internals. The current plan is to finish off most of the tooling required to install the aft fuselage parts that must be in place when closing the fuselage shells, and then ship the molds off to Brad Hill for first articles and then production. We've got definite requirements for three fuselage shell sets, and a tentative requirement for a fourth.

Today I finally got around to getting photos of some of the fuselage internals stuff. Over the next few days we'll be attending three different Thanksgiving dinners, but I'll probably sneak in at least one or two more half-days at the shop. The plan there is to do a bunch of mockup seating parts in the fuselage plug in order to set firm locations for the instrument glareshield, instrument panel, and canopy hinge and jettison mechanism. I'll start by installing a mockup of the knee hump where the control stick goes, and reference everything from there.

Anyhow, here's the latest photos:

A look down the aft fuselage with the five push-pull tube guide locators in place. The locators were carefully (at least as carefully as anything else in this project) built so that the shafts at the ends of the arms are all colinear. That insures that the elevator push-pull tube will be straight and free of preloads that would shorten the lives of the guide bearings.

Another view of the five locators. The locators install on studs embedded in the joggle flange feature for the left mold shell.

A closeup of the #1 locator. Note that the mounting is essentially a tripod, with one mounting stud at one end and two at the other.

Here's the #1 locator with a push-pull tube guide mounted on it. The guide is centered on the shaft of the locator with two temporary nylon bushings. What's missing is the fiberglass guide mount. Brad is going to make the tooling for the guide mounts, and use it to make the mounts. The idea is that you glue the guide into the mount, load the guide and mount onto the locator, butter the feet of the mount with schmoo, and then index the locator onto the mold so that the schlocked feet of the mount bond onto the inner surface of the fuselage shell. After the shcmoo cures, we remove the locator from the perfectly located and aligned elevator push-pull tube guide.

Here's a closeup of one of the push-pull tube guides. I first saw these when I was picking through the wreckage of Stu Tittle's LS6 - the one he crashed when attempting to take off with disconnected ailerons. Later, I saw these in the Aircraft Spruce catalog for about $10 each. I'd pay that for one or two, but the HP-24 will probably have something like 20 of them, so I tooled up and have made about 40 of them so far. Also, mine have 6 balls instead of the 4 in the ACS units.

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