Grand Esprit tail boom

[jbrandon]

Anyone know of a source for either a fiberglass or carbon tail boom to use for a Grand Esprit? Most of what I am finding are too small like around 1/2".

Thanks.

[Ollie]

Please give us dimensions: large end Dia., small end Dia., length and weight.

[jbrandon]

From the plans it looks like it is 32" long, 1" on the big end and 5/8" on the small end, I do not know the wall thickness or the weight. I will have a kit here by the end of next week but I never plan on building the kit. I am going to scratch build one in the next few months.

From experience I know the one supplied was a little whippy during launch and landings so I may want to beef it up some to help with those issues.

[Ollie]

The Supra tailboom has enough bending stiffness but it doesn't have torque stiffness for V-tail. So, I would beef it up with one or two layers of Carbon Braided Sleeve with epoxy, 0.6" Dia., 1.88" Circ., 0.04 oz./ft., 1k. Carbon tow braided to form sleeve. All data assumes 45 degree fiber orientation. However they can be reshaped +/-30%.

http://www.polecataero.com/products/tailbooms/
http://www.cstsales.com/carbon_fiber-ss3.html

[jbrandon]

Thanks Ollie but I was hoping to find an off the shelf item to use such as a fishing rod or something else but I have no idea of what. But if push comes to shove, I have to do what you suggest.

[fly1milehi]

Im not an expert in calculating the data to support my engineering theory but..... seems like the Bubble dancer tail boom has successfully been used as a V-tail, tailboom on the majestic kits and its 36 long 7/8th at the big end and 1/2 at the small end. Second idea would be Arthobby.com for the tailboom on their High Aspect 3.1M ...
Im thinking that the Grand Esprit orginally used a fiberglass tail boom? So the smaller diameters of the carbon booms shouldnt scare you away. Fiberglass boom is available from laserarts.com.. pretty sure it would be a close fit as well.

I would stay away from fishing pole rods since they are engineered to bend. Golf shafts are also designed to bend and flex but you can buy some extremely non-fexible golf shafts.. for about $120.00 a piece!
Greg

[jbrandon]

The Bubble Dancer boom would work, it is only slightly smaller on the big end. I was wanting to keep the airplane looking like the original and why I was looking for a fiberglass boom with the larger diameter. Years ago we used surf casting rods for booms but they did flex a little and were quite heavy.

This Grand will never be pushed all that hard, it will be my fun airplane to just push around the sky.

For some reason I thought the Supra boom was 1/2” on the big end, just read it wrong. And the booms on the Arthobby site look good also. I will email them to get the sizes and then decide.

Thanks for your helpful suggestions.

[schrederman]

You might try the Aerosphere guys to see where they are on the Grand Esprit. They might have a boom or two. I got a couple before Roy sold out. I had started one just before we moved. I have one outboard panel built... Will be doing more of it when the Yardbird is maidened... First one will be stock airfoil, but stronger spar and joiner... second one will have either 7037 airloil or the 3014... haven't decided yet...

Jack

[may fly]

I've got one of the later kits with the carbon boom. It is 1 3/16 X 9/16 X 34 and weighs 83g.

Bill

[jbrandon]

may_fly: That is good information, do you by any chance know who the supplier is/was?

[David Forbes]

I just got a couple of golf shafts used at the local golf shop, $2.50 each,to use for dlg boom mandrels, one is 68g the other 77g. 0.6 at the big end to .34 at the small end.

[schrederman]

I've been looking around for something a bit bigger that golf clubs. It struck me the other day at Sears... a pool cue. I believe you could roll your own on a $10- pool cue and be pretty happy with it. Probably would be close to the size requirements, too. I'm going to do one soon, but out of 2 layers of 1/64 plywood with some cf in between...

Jack Womack

[Esprit2]

... It struck me the other day at Sears... a pool cue. I believe you could roll your own on a $10- pool cue and be pretty happy with it.The original Airtronics part was a blank for making custom pool cue handles.

Tim

[Blaster]

Problem solved, we have a drop in replacement carbon boom @ 54 grams. It is our Supra boom.

Barry

[Esprit2]

Problem solved, we have a drop in replacement carbon boom @ 54 grams. It is our Supra boom.
Barry,

How about a link or URL?

Tim

[jbrandon]

While it is not a direct drop in replacement it could be made to work. It has a .760" butt.

http://www.polecataero.com/products/tailbooms/ (http://www.polecataero.com/products/tailbooms/)

I inquired at Arthobby and they responded with this information:

Tail boom (High Aspect):
23mm inside diameter of larger end
710mm length

http://www.arthobby.com/shop.html

Look down at the High Aspect 3.1 M and you will find 057B tailboom. I have ordered one but there online ordering is funny. Said I had ordered one but never ask for payment.

[Blaster]

URL is http://www.kennedycomposites.com/.

It is not listed as a seperate item under the Supra page as yet. Price is $ 40 + $ 5 shipping.

Barry

[apage]

Barry,

What are the dimensions of the Supra boom?

Thanks!

[jbrandon]

Received the Airtornics Grand Esprit kit today and the here are the dimensions of the boom:

34” (865mm) long
1.186” (30.32mm) big end (OD)
.6” (15.17mm) small end (OD)
3.89oz (110g)
.040 (1.0mm) wall thickness uniform the whole length

Color is a brown and the outside has been sanded. The boom appears to have been laid up on a mandrel and then sanded to the wall thickness. Fiber grain can be seen running the length of the boom. The boom is very rigid with almost no deflection.

[Ollie]

"Received the Airtornics Grand Esprit kit today and the here are the dimensions of the boom:

34” (865mm) long
1.186” (30.32mm) big end (OD)
.6” (15.17mm) small end (OD)
3.89oz (110g)
.040 (0.1mm) wall thickness uniform the whole length"

I think the thickness is about one mm rather than 0.1 mm.

[schrederman]

I just drug out one of the G. E. carbon tail booms that I got from Dreamcatcher. Interestingly, the dimensions are the same... or close enough... to the stock boom. However. as I was sighting down it, it became evident that it doesn't taper all the way. The last 9" or so are straight... on the big end. The means that it is about 1 3/16 O. D. for 9" and then tapers over the last 25" to 9/16" O. D.

It would be interesting to know if the stock one does the same or if this was a mod by Dreamcatcher...

Jack Womack

[schrederman]

And ... by the way ... I'm extremely jealous of anyone that has an Airtronics kit...

JW

[jbrandon]

And ... by the way ... I'm extremely jealous of anyone that has an Airtronics kit...

JW
Well, I will tell you I paid dearly for it! When I was flying back in 70-80’s it was an airplane I always wanted but never could afford. The kit, plans – even the box is pristine. No one has even taken the bags out that are stapled to the sides. There are only two layers of tape holding the box closed. I don’t think I will build the kit - at least not now for now.

I checked the boom from the kit and it is tapered all the way. I will probably scratch build one even if I have to make the boom myself. I really want stay away from carbon if I can and I want to try to stay authentic on the outside (stand off scale?). I will change the airfoil and beef the spars and joiner rod but that is probably all I will change and I will use a computer radio for the V tail and not the mechanical mixer. I also have the plans for the Super Esprit and I may build that one instead, since I have to make the boom anyway. But that will be down the line about three planes.

[Esprit2]

It would be interesting to know if the stock one does the same or if this was a mod by Dreamcatcher...
Jack,
A mod by Dream Catcher.

The Airtronics boom was a handle-blank for making custom pool cues and, as such, is tapered full length. I have both an Airtronics kit and a DC short kit, and I never noticed the straight section on the DC boom. Now I'll have to go take a look just to satisfy my curiosity.

I'm guessing here, but DC probably made the change to make fitting the boom into the fuselage less of a craftsmanship challenge. A constant diameter tube can be slipped back and forth in the formers without worrying about exactly where the formers were. The tapered boom fits properly in only one position and the formers need to be spaced correctly (which is no big deal).

Moving the Airtronics tapered boom back and forth would affect the fit in the formers, while DC's version is neutral with regards to position. The Airtronics version worked just fine and didn't pose any problems to a builder who's skills were appropriate for that level of kit overall. And it allowed the use of a found part while DC's design required a purpose-built boom.

My son is all jazzed up about the carbon fiber DC boom and I have more of an old dog's affinity for the original kit. When the plane is built, the differences are transparent, so I guess we'll both be happy.

My old Grand Esprit that was built back in the (??) late 70's - early 80's is still flying (or will be when I unpack from the move). The stock spar gives lots of wing flex on launch, but I don't fly it like a modern ship. Having the benefit of 30 years of hindsight, I'd have to say the original spar and joiner are pretty lame by any measure and in need of some beef. But overall, it's a great plane as long as you accept it for what it is and learn to pedal the winch.

Tim

[ejett]

And ... by the way ... I'm extremely jealous of anyone that has an Airtronics kit...

JW

Actually, I have an original Airtronics kit and a Dreamcatcher short kit. Thus I have both booms. I will dig them out and do some measuring and post the results.

EJ
Athens, LA

BTW, I see you got your Skybird finished and flying.

[schrederman]

Hello Ed,

Yep, she flys really well. It's my only flying glider right now. I have a Dragonfly that I've had ready to fly for weeks, but the weather won't cooperate. My Hawk is still broken and my Yardbird is still not finished... and I can't go to the Southwest Classic because I have to build a 400' tower... ssoooo..... are you feeling sorry enough to send me the Grand Esprit kit yet, or should I ramble on... :p ... you lucky dog...I'd send it back built, but it might have a few hundred flight hours on it... :eek:

See ya...

Jack