ProBroJoe

OK guys, I've been itchin' to build sumthin' for the last couple of months, and have come up with this, errrr, ummmm, idea...

I'm thinking of building another Lady Hawk RC rocket glider, but this one will have a removable balsa nose block that will allow me to bolt on a Norvel .061 / .074 - for when rocket power gets cost prohibitive. I don't see a whole lot of problem with the "conversion" as there's plenty of room in the fuselage for a fuel tank and for moving the battery around to achieve the proper CG in rocket -vs- glow mode...

The .061 would be the simplest & cleanest install as I could just make "F1" 1/8" ply and bolt on a Dave Brown .061 mount, and probably even get it cowled in somewhat nicely. (The replaceable nose block would use the same the bolt pattern of the mount...) The .074 would be little harder due to it's extra width and would look more of an after thought.

So, whattyall think - would the .061 be enough? (I have an AME and a Big Mig to choose from.) The plane has a 24" wingspan, and weighs in at around 12-14 oz... so I'm thinking it's not going to much a speed demon with the .061, but should do fairly well. But then again, after flying the thing on Aerotech's F25 and F39s, just tooling around on the .061 would be a little boring... so maybe, perhaps, the .074 is the way to go? I guess I'm hoping to be fairly fast on glow - at least enough to be interesting...

Am I nuts or am I just over thinking the thing and should just go for it?

-Joe

gkamysz

My Feedback: (19)

I say go for it. We had electric Positrons that flew just fine with flat plate airfoils and Speed 400's. I think they 18-20" in span?

tangerine-jack

What is not sane and logical about your idea? Why haven't you already done it? It's a perfectly rational idea to me, I just wish I thought of it first..

vicman

My Feedback: (10)

If I didn't have 3 Q500s on the bench right now I would do a build along with you! I've wanted to build a Ladyhawk for a lonnnng time.[sm=thumbup.gif]

combatpigg

My Feedback: (3)

Have fun with it PBJ! If you pull it off, it'll be a "1st" for around here.

build light

The .061 should be enough to give you a good time for sure.
I do see a real problem with putting the engine in the nose. I just don't see how you will get enough lead ballast behind the CG to get it to balance On the CG. KnowwhutImean Verne? That is if you want the plane to keep its natural look. If you were to lop off the nose moment enough to make a huge difference in getting it to balance it just would not look the same.
In addition If you were to shorten the nose much it would adversely affect the rocket motor ability

You would be doing yourself a large favor by mounting it as a pusher. The nose may still be removable to adjust ballast between power choices.

I just thought of something. Suppose you made the nose removeable right at the firewall? And have the firewall just at or behind the root of the LE?
That could make a huge difference!

This, if you were to mount the I/C engine up front with the firewall at the LE
Looks very much like the plane Art had with the D Estes engine that I mentioned to Combatpigg in another thread.
Art was in the Coast Guard and though it looked like a delta winged fighter jet yet it sported U.S.C.G. colors! It was really cool to see. He had it wired so that when he did a long dive and leveled off in a low strafing sort of run, he would light off the D engine and it would go like stink and then he would pull up and do a very fast verticle climb. You had to be there to really appreciate the event.

I would love to see you make this thing work.

Robert

Lost Glider

Put da injun at da rear. ???

Rocket engines don't cause tork roll.

buzzard bait

The old RCM "Pelta" (pusher delta) had a Mill .75 cc diesel in the back. Span was 29 inches and it was single channel, ailerons only! Very cool looking plane.

I think it's a terrific idea and I totally agree with mounting the engine in the back. If you look at deltas with front mounted engines you will see that they all have practically no nose and the engine is mounted at the vertex of the delta. So if you want to preserve that cool, long sleek look, I think you need to put the engine in the back. Have fun, keep posting, and be careful with the launch!

Jim

icerinkdad

Actually you might want to consider using an expended rocket motor and mount a plywood firewall to that to put the motor on.... makng it a convertable.
Bob

ProBroJoe

Thanks for all the great suggestions guys! You all have brought out some pretty good points - especially when it comes to that looooong nose moment... []

I have thought of making it a pusher, with a cartridge style "power pod", that swaps out both motor tubes and exchanges them with a mounted engine/fuel tank combo but that will complicate the build and definitely cause a loss of momentum (not a good thing when I only have a few minutes a day to work on it).

The "spent engine" power pod idea is neat too, but the design of the model dictates that the rocket engine's thrust is on an angle to go through the CG (I think) or maybe it's the "rocket's" Center of Pressure... I'm not sure... I don't want to go and change a whole lot and cause a bunch of uncertainly. (I know the thing flies great under rocket as designed and makes for a fun little slope soarer!)

Now.... build light may be onto something with the glow engine's firewall moved back to the wing's LE root and the forward nose portion being reattached for rocket powered flight.... I just don't know how I'd make it look right with the fuselage being as tall as it is (being that it needs to accommodate the twin rocket motor tubes in the back). and of course the twin motor tubes are there in case a person wants to air start one... and having the option because it gives me a wide range propulsion - anything from Estes D11s to Aerotech's F39s!!!

Oh boy.... what to do.... what to do.... I think I'm going to look a the leading edge mounted glow engine option... It'd be great to make it so the conversion only takes a couple of minutes and looks the part either way. Oh, it looks so sweet though with that long nose and tractor prop!!!

Must. Stay. Focused. (Now if I only had a partner in crime... VICMAN!)

jeffie8696

Joe, you certainly are a loony. But I applaud your efforts.
You knew that already.

build light

Quote by ProBroJoe:

"I just don't know how I'd make it look right with the fuselage being as tall as it is "

That is no problem sir. All you have to do is make a special spinner with the base being as wide as the fuselage and about, I'm guessing seven inches long! You could name your version Cyrano de Bergerac!
Or how about Pinnochio!
I would suggest no one being anywhere except behind the prop arc when running!

Robert

buzzard bait

If you put it on the front with the firewall moved back to the root it will just look like every other delta.

Another option - build the vertical fin strong and mount the engine on a pod in tractor mode like a Northstar.

But I think best would be firewall in back, fuel tank in the body and engine in pusher mode mounted at 9 o'clock to get the carb in the correct relation to the tank. Then lots of room to move the radio forward to get the CG right without adding any ballast.

Man, you've got me thinkin'!

Jim

vicman

My Feedback: (10)

Yer killin me man! I seriously have to finish these quickies otherwise I'll be watching all season. I've been wanting to do this thing forever.

combatpigg

My Feedback: (3)

I don't see how it can be pulled off without making interchangable cartridges [power modules] for the aft end. I can visualize a nylon bolt and some doweling to make swapping a 2 minute deal.

Being a high wing design, the low thrust line of the rockets must require some slight down thrust. My experience with a similar layout powered with TD / AME engines worked fine with zero thrust angle.
The Grish 6x3 trimmed to 5x3 performed well. It had to, it was my only pusher prop!

ProBroJoe

I was thinking some more about this last night (of course I was) and got to wondering... suppose my battery, which typically goes in the forward nose section, weighs as much as a spent rocket engine (which is does) and suppose, my Norvel .061 weighed as much as the spent rocket engine.... wouldn't I (in theory) be able to remove the spent rocket engine, move the battery to the rear (in the rocket engine mount), and stick the Norvel on the nose? Follow me? Here are the weights:

Aerotech 24mm 20-40 reloadable rocket engine: 1.0 oz
Great Planes 350mAh NiMh 4.8 V battery: 1 1/8 oz
Norvel .061 AME: 1 1/2 oz (w/ Fuji film can Fuel fuel tank 2.0 oz)


Hmmmmmm..... I think if I biased the servos to the rear of the plane to begin with, and go up a size on the RX battery, say a 750mAh NiMh @ 2.0 oz, I may be able to pull this off and retain that sexy looooooong nose moment...

So.... in order to retain momentum, I'm going to build the model pretty much as designed with the exception of making former F1 out of 1/8" ply instead of balsa. I'll drill the new F1 / firewall for Dave Brown 1/2A engine mount, then assemble the plane as a rocket-only plane. If I feel the need to fly it as a glow model, I'll lop off the nose right at F1, stick on the Norvel and throw a bigger battery in the tail. This thing really has a light wing loading so the extra weight of a bigger battery and fuel tank shouldn't make much difference....

I don't want to re engineer this thing because I know how I fuss over the details and never get anything done - like the three other "great intention" models that I started over the past year.

So who's with me? Vic? Jim?

jeffie8696

Joe, relax and enjoy the hobby.

ProBroJoe

Well, I had a nice, relaxing evening, whittling on some balsa and ply...

jeffie8696

Any cigars?
No wonder it was so quiet around here.

gcb

Have you considered adding sheet balsa delta fins near the nose for additional lift and going with the forward engine?

George

ProBroJoe

Ohhhhh, you mean like a canard of sorts? No I haven't... (you're assuming I have a drop or two of imagination). What must that do to the CG / CP?

Whenever I get to thinking too much about a project it usually ends up part-way built because of a few details, so, in this case I'm going to cut my losses and build it as a rocket-only plane with a few built-in provisions should I feel the need again to convert it to glow... (like the plywood firewall, rearward servo location, etc...)

So, with that being said, here's what I can get done when I don't have to think! ;-)

ProBroJoe

Moving right along....

OzMo

My Feedback: (3)

PBJ'
Lookin' good! I think this group will be very good at lending the moral support you requested but the other part?????

ProBroJoe

Little more progress...

I hope to have her completed in time for the 14th anniversary of my first Lady Hawk's maiden flight, which was Feb. 26th, 1995... I think it's very doable!

Oh yea, the bare airframe as it stands is right at 4 ounces, so my goal of an AUW at around 12 ounces seems obtainable.

vicman

My Feedback: (10)

Nice work surface there.
Forget moral support, I'm sending him my address. We can do GRACE all over again.