in the shops 19 Sep
|Tony Nijhuis||06/06/2012 23:40:21|
601 forum posts
Now here's a pic of the new Vulcan.....one of two sizes,,, the smaller being 48" and the larger being 78". The larger is sorted and will have a couple of 90mm fans or a single 44 size turbine (yes only a single!!!!)
The 48" is proving a problem due mainly to it's size. The pic shows the 48" with a couple of 68mm fans, but the weight is creeping up to 6lbs plus due to the complexity of the design and hand launching will become an issues. I have added some micro retracts but the wheels will be too small to prove useful either landing or take off (unless on tarmac) so I'm thinking of ditching the fans on this smaller version and going for a electric tractor and keeping it all very simple
just need to gauge the responce from the masses out there so all sensible comments welcome
|Tony Bennett||06/06/2012 23:43:24|
5079 forum posts
maybe an electric pusher would look better.
|Stephen Jones||06/06/2012 23:46:36|
2737 forum posts
I reckon a 50 50 split here as there will be plenty wanting the fan and settling for a bungee launch .
And at that weight the safest way will be the bungee
|A.A. Barry||07/06/2012 00:16:19|
1922 forum posts
I agree with Tony Bennet, EP pusher
For C/G would it balnce better with the motor on the Ft or Rear ?? saving adding weight
Edited By A.A. Barry on 07/06/2012 00:22:19
|Lindsay Todd||07/06/2012 00:26:22|
1703 forum posts
Presumably the weight increase includes the impact of a spar incorparating the ducts to maintain strength in the airframe. Moving to a pusher format would surely be a retro step for this effort and would be further compromised by increased drag of none functional ducts. I can't help feeling that as Tony suggests a tractor set up is the best compromise for a good performance, that is unless you go pss and chuck it off a cliff - problem solved
|Colin Bernard||07/06/2012 06:08:24|
481 forum posts
My own view is that to have any sort of prop on this beauty would be sacrilege!
If it is simply a choice of having a prop driven Vulcan versus needing to use a bungee or dolly, then the latter wins for me. Once it is in the air then there are no props to spoil those long low flypasts.
1234 forum posts
I would consider building the small one as a pusher, but not as a tractor.
Far be it from me to instruct the great TN on aircraft design (I've learned soo much from building two of your designs) but so you know my reasoning for the answer...
Pushers tend to spoil the lines less. A tractor won't look like a vulcan with the iconic nose. A pusher with a spinner in the aft cone probably could be well hidden, especially if you used an inrunner. I understand that pushers are more efficient too.
102 forum posts
I would go for two small pushers on the trailing edge of the wing but give a few hints on the plan to anyone who wants to go EDF?
|Piers Bowlan||07/06/2012 09:52:39|
1904 forum posts
I have had a Wren 44 sitting on my bench for the last three years; sacrilege I know! I purchased a plan of Graham Dorschell's 68in Vulcan with a view to heavily modifying it (redesign) to accomodate the Wren. However this would be a big job and I have little time for a project like this. I wasn't particularly bothered by the prospect of a single jet exhaust as I am not a purist, I just wanted to capture the character (wing shape) and turbine sound of this legendary aeroplane.
It is exciting that TN has produced a 78in span Vulcan for EDF or Turbine, I have no doubt that it will build well and fly superbly. Can't wait to order the plan and start cutting balsa- I will just have to MAKE the time!
As far as the 48" span Vulcan is concerned I would prefer a pusher prop configuration but care would be required for hand launching if inadvertent digit removal is to be avoided!
|Alan Randall||07/06/2012 10:32:40|
446 forum posts
I would also opt for twin pushers.. I have a atand off scale Vulcan made in depron with a single pusher prop, and have no difficulty hand launching that.
|Keith Simmons||07/06/2012 13:49:18|
|446 forum posts|
Perhaps a single pusher and ditch the retracts for the smaller Vulcan. Have the ducting open from front to rear to reduce drag. Can have twin brushless on the outer engine exhausts.
I will go for the larger model and have EDF. Can't wait ...
|Frank Skilbeck||07/06/2012 14:02:01|
4514 forum posts
Make the 48" a PSS Maybe the 78" version should be for 2 x Jet Cat P20's or Kolibri's.
Keith - keeping the ducting open will increase drag by the way.
Edited By Frank Skilbeck on 07/06/2012 14:04:27
|Tony Nijhuis||07/06/2012 14:25:21|
601 forum posts
Some good ideas.......I do like the twin pushers idea......keep them coming
Frank you are spot on....if you dont need the ducts....block them up
|Reno Racer||07/06/2012 14:26:44|
1136 forum posts
For the smaller 48" one, a twin 70mm EDF for catapult ramp launch. I fear twin pusher props might get a bit finger hungry for hand launching.
Very interested in the twin 90mm EDF, assuming it doesn't get too heavy which then means more expensive higher powered fans/lipos etc in that vicious power/weight/duration cyclone. Using cheaper and less efficient HK type lower powered fans would be better, but i guess the AUW would have to be sub 8-9Lbs to get any performance without massive A draw.
My 6S Jepe fan is great and kicks out 6.5 lbs (1250W) of thrust for 54A, but that costs a fair bit and two would only give 13lbs of thrust max so I guess at 200 watts/lb the AUW would have to be about 12Lbs. Still I suppose cheaper than a WREN 44!
|Tim C||07/06/2012 14:42:10|
496 forum posts
Stick with the EDF and bungee lauch, props would be sacrilge
|graham kindberg1||07/06/2012 15:13:37|
129 forum posts
A couple of HK 64 mm 2nd generation fans will pull 1500 watts with the right batteries, do away with the retracts, stay light, and bungee/catapult launch. May not be what the masses would understand, but it would work. Offer several options in the design. I would be happy to cobble one together with the twin fan set up to prove that option. Have done that with the NH Tornado.
|pete taylor||07/06/2012 15:52:42|
348 forum posts
For what it's worth, I think I'd be tempted to adapt the design for twin pusher configuration anyway.
|Chris Bott - Moderator||07/06/2012 17:18:47|
6674 forum posts
I too think pushers are far less obtrusive than props at the front.
|Tony Nijhuis||07/06/2012 21:24:47|
601 forum posts
As for the 48" fan version it's all but finished so the plan is to give it a go anyway, It will work as it has a couple of 68mm Lander fan but that is where the weight has come from i think!
I'm thinking I will build another version for prop drive and get the model flying first so i'm comfortable with flight characteristics before bungeeing something untested.....
any more comments?
PS... The 78" version will have a couple of 90mm Lander fans on 8s lipo so hoping for an AUW of 12lbs should see much better set up
|A.A. Barry||08/06/2012 00:15:46|
1922 forum posts
How about using props inplace of the fans, have a slot in the wing for them to turn in, once they where spinning, one would hardly even see them
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