Sud Caravelle? - RC Groups
Thread Tools
Feb 07, 2017, 01:19 PM
A Day @ a Time - Matt. 6:25-34
ruff1's Avatar
Question

Sud Caravelle?


Hey DD, you gonna build a Caravelle anytime in the near future? We talked about this a few years ago.

I think Ethan's approach is likely the only way to get scale looks and make her airworthy. The JT8D engines don't have a very large inlet. Seeing your 40 mm edfs on the 747 thread brought this to mind. I haven't done any calculations but I wonder what the size of the airplane would be with these motors?

This baby will need to be built very light. Maybe even using some of Mr. Tritle's techniques and skipping landing gear altogether. I fly at a grass airstrip. Thoughts?

If I were done with the 4-0-4 I would love to give this one a shot.

I have a circa 1963 Revelle SAS Caravelle still in the box. Simple lines, she should be a straightforward build. I have learned so much about scratchbuilding with the 4-0-4.

Kevin
Sign up now
to remove ads between posts
Feb 07, 2017, 01:36 PM
A Day @ a Time - Matt. 6:25-34
ruff1's Avatar
Out of curiosity, I couldn't resist sizing up the 40 mm edfs with the full size. They translate to 1:22 scale when compared with the Rolls Royce Avon inlet size. That puts the wingspan at 5.1 feet at that scale that is right in my wheel house.

Any idea how much thrust you are/will get with the edfs on the 747?
Feb 07, 2017, 02:02 PM
Registered User
That would be an amazing project !
Feb 07, 2017, 03:00 PM
Registered User
Dirty Dee's Avatar
Those engines look comically small

definitely would take some thought to make a flying EDF without ruining the proportions

Feb 07, 2017, 03:58 PM
A Day @ a Time - Matt. 6:25-34
ruff1's Avatar
Yes it will be an extreme challenge. The idea of a Guillows- type lightweight frame with monocote covering may be the only way. Perhaps something in foam might still be doable. I'm not really rigged up to do something in balsa.

Thanks for posting an excellent picture that really highlights the challenge.
Feb 07, 2017, 04:22 PM
Up-Out-&-Gone
demondriver's Avatar
Quote:
Originally Posted by ruff1
Hey DD, you gonna build a Caravelle anytime in the near future? We talked about this a few years ago.

I think Ethan's approach is likely the only way to get scale looks and make her airworthy. The JT8D engines don't have a very large inlet. Seeing your 40 mm edfs on the 747 thread brought this to mind. I haven't done any calculations but I wonder what the size of the airplane would be with these motors?

This baby will need to be built very light. Maybe even using some of Mr. Tritle's techniques and skipping landing gear altogether. I fly at a grass airstrip. Thoughts?

If I were done with the 4-0-4 I would love to give this one a shot.

I have a circa 1963 Revelle SAS Caravelle still in the box. Simple lines, she should be a straightforward build. I have learned so much about scratchbuilding with the 4-0-4.

Kevin
Lol, yes indeed Kevin I'm building a 10 foot Caravelle. . . . Three to be more precise.
With the Caravelle's modest wingsweep and 4 wheel gear truck they are perfect for Grass RC runways.
And thats why I'm building them, I started them a few months before I moved and thier parts are in storage at the moment, they are designed around 2 90mm or 2 100mm edf units.

I'll start the official build thread after I complete my customer's 767-300F.
Latest blog entry: Three RC 737 Progress Report!
Feb 07, 2017, 04:26 PM
Up-Out-&-Gone
demondriver's Avatar
Quote:
Originally Posted by ruff1
Hey DD, you gonna build a Caravelle anytime in the near future? We talked about this a few years ago.

I think Ethan's approach is likely the only way to get scale looks and make her airworthy. The JT8D engines don't have a very large inlet. Seeing your 40 mm edfs on the 747 thread brought this to mind. I haven't done any calculations but I wonder what the size of the airplane would be with these motors?

This baby will need to be built very light. Maybe even using some of Mr. Tritle's techniques and skipping landing gear altogether. I fly at a grass airstrip. Thoughts?

If I were done with the 4-0-4 I would love to give this one a shot.

I have a circa 1963 Revelle SAS Caravelle still in the box. Simple lines, she should be a straightforward build. I have learned so much about scratchbuilding with the 4-0-4.

Kevin
To be honest Kevin, you need to build your own Caravelle Sir.
Latest blog entry: Three RC 737 Progress Report!
Feb 07, 2017, 05:03 PM
A Day @ a Time - Matt. 6:25-34
ruff1's Avatar
Yep, you are right. I'm running some numbers right now.

Believe it or not, the wingspan comes in at 61 inches, the same as the Martin 4-0-4! I figure this is my destiny.

I will research the 40 mm edfs out there to see what kind of performance is available.
Feb 07, 2017, 05:36 PM
Registered User
Norbert Rauch has recently started a buildlog of his 84'' Caravelle:

http://rauch-airliner.com/Bau(1)Caravelle.htm

http://rauch-airliner.com/CaravE.htm
Feb 07, 2017, 05:37 PM
A Day @ a Time - Matt. 6:25-34
ruff1's Avatar
Nice.
Feb 07, 2017, 05:45 PM
Registered User
Dirty Dee's Avatar
looks like the nacelles were sized up a bit to fit larger units on the Rauch model.
Feb 07, 2017, 06:09 PM
A Day @ a Time - Matt. 6:25-34
ruff1's Avatar
Mr. Rauch's build certainly takes a heavy-duty approach. I calculated the wing cubic loading at 13.8. That is at the high end of scale, it will need some get up and go to keep flying. Don't get me wrong, his stuff is great (I can't claim anything since I'm still working on my first scratchbuilt airliner).

My initial idea of approaching this build will be to build light. I didn't use a whole lot of restraint on my Martin 4-0-4 and she will come in at about 5 pounds auw. The Caravelle at 1:22 scale will have a 61 inch wingspan just like the Martin. Looking at wing cubic loading with 550 square inches wing area or maybe a bit deeper chord at the tip to get more area, if I can keep her at 3.5 pounds the wcl comes in at 7.8, right at the top of the trainer range. A quick check finds a Dr. Mad Thrust 40 mm edf producing around 14 ounces max (a supposed realistic number). That results in a just a bit under .5:1 thrust to weight ratio. That should work with the wing loading.

My club has a catapult launcher at the field, so if I skip the landing gear getting these numbers look realistic. Not having to beef up the wing and skipping the landing gear will save a lot of weight. Using FFF for the fuselage will make it strong enough for belly landings on grass. I used a 2 inch PVC pipe to shape the FFF on the Martin and it came out great.

I welcome any feedback and comments. I will run some more numbers to check stall and top speed. Not looking for a screamer...
Feb 07, 2017, 06:11 PM
Up-Out-&-Gone
demondriver's Avatar
Those two Caravelle fuse sections are a few I've hotwired so Far, the nose sections are back there somewhere too.
Latest blog entry: Three RC 737 Progress Report!
Feb 07, 2017, 06:13 PM
Registered User
Early Caravelles had Rolls-Royce turbines with long and thin nacelles. Later variants were powered by Pratt&Whitney turbines with slightly bigger nacelles. Also the cockpit windows were enlarged.
The Rauch Caravelle looks more like these later variants.
Feb 07, 2017, 06:18 PM
A Day @ a Time - Matt. 6:25-34
ruff1's Avatar
One nagging question is the nacelles. They will probably 4x the length of the edfs; for those of you engineering types or those who have figured this out, what does this do to the thrust? I have read somewhere that you don't want a whole lot of outlet material behind the edf housing. Can someone chime in on this please? Of course, placement at the front of the nacelle will help with CG, but battery placement can overcome any absolute requirement for placing the units for optimal thrust.


Thread Tools