HL-10 One-Off Proto Build - RC Groups
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Oct 26, 2013, 01:44 PM
AndyKunz's Avatar
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HL-10 One-Off Proto Build


I mentioned here https://www.rcgroups.com/forums/show...postcount=2708 that I was starting on a one-off build of the HL-10. This model will be a learning tool for building a larger model. The intention is that it will fly, and that some of the flying will be done to test questions I have, before committing to the larger one.

I'm building it directly off the attached 3-views, fixing them as we build, so that when I get to drawing plans they will be correct. It's not unusual to get drawings with errors in them, so you need to carefully review every drawing and compare it with photographs (I have several hundred collected now for this plane).

The attached drawing is representative of the original build of the plane. One change was made which afterwards which we'll touch on when we get there. I'll also point out the errors in the drawing (one is glaringly obvious) as we find them.

For all of you who remember the Six Million Dollar Man, this is going to be fun!

Andy
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Oct 26, 2013, 02:17 PM
An itch?. Scratch build.
eflightray's Avatar
This video is interesting regarding the HL-10. it explains how they over came some of the handling problems.

I do hope you intend building a scale B-52 to carry it to launch height


Northrop NASA Lifting Body Tests HL-10, M2-F2, M2-F3 (3 min 57 sec)
Oct 26, 2013, 02:17 PM
AndyKunz's Avatar
Answer to a few questions (you can post them in the thread, it's OK):

1) What size? Why?

It's about 14" long and 3" thick. I want it small enough to use micro gear, but not too small. This was the size it came out on my plotter in a "fit to paper" mode, and the 3" thickness works out well for the wood width.

2) Power?

I do not expect to actually power it, but I will put in a BT-5 tube which will serve as a reference for the big model.

3) How much will it weigh?

I don't know yet. A scale density would put it at about 1 pound. They called these "heavyweights" when they built the originals. One of my own questions is, "How heavy should it be to fly similar to the full-scale, but still be usable as a model?" There will be a ballast capability in the model to explore the answer.

4) How will you launch it?

Yeah, that's a good one! It depends. I will probably try below a helicopter (NASA has done this with models) or off the top of an Apprentice, like how the Shuttle Enterprise flew off the 747. I would also like to try an aero-tow.

5) What radio gear? How many channels?

That will be part of the test. I will initially try using a stock AR6410, to see how well it responds. I may also try the Hyper-Taxi receiver, since it has AS3X in an elevon configuration (EFLU4751). I plan to use A2010 or A2020 servos since these will help me plan alignments for the larger model. Weight is probably not going to be much of an issue (for a change).

This model will only be 3 channels with the AR6410 (2 elevons, rudder) and 2 channels with the Hyper Taxi board. That's because the Hyper Taxi doesn't have the right gyro mixing on the rudder. I might put the rudder on a different non-gyro channel. It depends on how necessary the rudder is, and if the strong Dutch roll of the model is controllable by AS3X.

Thanks for asking. Do it in the thread instead of PM!

Andy
Oct 26, 2013, 02:19 PM
AndyKunz's Avatar
Quote:
Originally Posted by eflightray
I do hope you intend building a scale B-52 to carry it to launch height
I'll let you do that, Ray! Thanks for posting the link to the video. There are lots of good ones out there - just google for "HL-10 video" guys!

Andy
Oct 26, 2013, 03:05 PM
Jim C Patrick
jcpatrick's Avatar
Andy, has you seen other plans or prints? There's some here, but they came from the Unwanted Blog (up-ship.com). The Unwanted Blog has art here, drawings (part 1 and part 2), and more cutaways. Aerospace Project Reviews has some sections too.

Hope that helps a little with proportional drawings.
Oct 26, 2013, 03:23 PM
AndyKunz's Avatar
Quote:
Originally Posted by jcpatrick
Andy, has you seen other plans or prints?
Yes, those and more. I've been noodling on this project for a few decades, and have tons of photos, drawings, and videos. Several books written by the pilots have been very helpful as well.

The Up-Ship stuff was not as useful as the NASA drawing I attached. There are discrepancies even between NASA drawings.

The Aerospace people were not careful to distinguish between HL-20 and HL-10. It is not uncommon to find HL-20 stuff with HL-10 in the name.

Thanks. It's good background material for interested readers.

Andy

BTW, if you look at the end of the RPF thread, you'll see a familiar name as the last poster
Last edited by AndyKunz; Nov 09, 2013 at 08:20 PM. Reason: Fix typo for therpf.com
Oct 26, 2013, 04:51 PM
B for Bruce
BMatthews's Avatar
Andy, keep in mind that you'll have that whole nasty Reynolds number issue dogging your heels. At the size you are proposing I'd want to start a LOT lighter than the one pound mark. You can always ballast. But it's tougher to chop out weight.

From what I see in the full size craft a high flying speed counts for much of the lift generation. It'll be interesting to see where this one goes.
Oct 26, 2013, 05:50 PM
AndyKunz's Avatar
Yes, of course, Bruce. It'll be a lot lighter, but I've already played around with some similar stuff in the past, so I'm not exactly on virgin ground here. I think I already noted that it's going to include a ballast box.

If velocity is too low it won't fly properly. If I want "realistic" (there's a subjective term for you) flight, it's going to be a heavier wing loading than the Classic Pattern planes I normally build this size.

Andy
Oct 26, 2013, 06:07 PM
AndyKunz's Avatar
Because weight and strength doesn't matter (much - it's not intended to have a long life of flying, and we'll be ballasting it to get a good flight speed), I'm using some really bad wood to build this. When you see wavy grain, knots, and other defects, remember it's because the wood isn't suitable for my "good" models. This is a great way to clean the junk out of the woodpile

The formers were made by making 10 copies of the front view, arranged on the paper so I could fold it in half on the C/L and get both sides to match. I then compared the thickness of each former to the stations on the side view and they all matched pretty well except for station I. That one just looked wrong, with the undercut on the bottom and the different taper on the side. The side is probably OK, but the thickness was off by 3/32" each side of the horizontal reference line. I made another copy, marked where the side view showed the thickness to be, and re-cut the pattern.

Because the top view doesn't have the stations marked on it, and the top and side are not aligned perfectly, I decided not to check the width of each former. I would have normally done that, but I figure a little sandpaper or glue and #11 will fix anything later. For now this is "good enough."

The formers are going to be assembled onto a crutch which consists of an Estes BT-5 rocket body tube on the centerline plus upper and lower longerons that are taken from the side view. One item that will be preserved is the marked CG location. It isn't common to see it marked in both axes, and according to the books I've read by the lifting body pilots, the vertical axis is quite important, so we're going to keep that. The vertical position of the CG is right at the bottom edge of the BT-5 tube, which I have offset a constant amount to do this.

OK, so that brings us to this batch of pictures. I think the captions pretty well cover what I did. I've been working on this paragraph as I did each step since post #2, so I apologize for the inaccurate verb tenses.

Two things to note: At this size, there are a lot more formers in there than it needs. I even removed one (H) because it was so close to the others (redundant) and incorrect.

Andy
Oct 26, 2013, 06:08 PM
Registered User
jpurcha's Avatar

Going to need a pilot.


You are going to need a pilot.

Jim

Intro - Six Million Dollar Man (1 min 27 sec)
Oct 26, 2013, 06:12 PM
AndyKunz's Avatar
I think the AS3X in the cockpit will help a little It'll be bionic from the get-go!

Andy
Oct 26, 2013, 06:13 PM
Registered User
jpurcha's Avatar
Great build. I imagined doing this one as a kid while watching the show.

Jim
Oct 26, 2013, 06:16 PM
AndyKunz's Avatar
Do it now! Or you can wait until next summer and get the plans for the big one.

Andy
Oct 26, 2013, 11:11 PM
AndyKunz's Avatar
After allowing the glue to dry for several hours, I sanded the formers to match them up a bit. This showed me that my "I" former was still bad (short) so I'll need to add a little on the tips to make it fit the covering well.

I marked where to add notches for 1/8" sq stringers. These are at the limits of the "flat" (single curve) top and bottom portions. Once these stringers are in place I will be free to remove the inner areas from some rear formers to reduce weight and shift the balance forward a bit.

It's Saturday night - see you in church tomorrow!

Andy
Oct 27, 2013, 09:01 AM
An itch?. Scratch build.
eflightray's Avatar
Have you looked at what others may have tried ?

I did a Search on Lifting Bodies, setting it to Show Threads, and quite a list of threads came up.

Supersonic Mike has worked on something similar, (threads show as being in his Blog), plus a few others.

I know we all like to 'reinvent the wheel', but there may be some useful info around that someone may have solved potential problems.

My square wheeled car was a bit of a failure, people seemed to think it made them feel sick as it drove along.


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