foodstick

I have some slightly enlarged plans for an old tow glider called the Super Sinbad. If you have seen one you know its has nice lines to it. Years ago I built the fuse and tail so that it could use a Gentle Lady wing. It would probably still work but I just don't think that wing will look right...
With the electric power out there now I think the NEW eventual goal is a power pod on the planes wing. I have been kicking around the idea of using a much better airfoil than the design used in the 30? 40s?

Is their another flat bottom airfoil out there that would be a smart replacement ? I admit I don't know anyone that has flown this design..but I am guessing the airfoil is far from being great.

This fuse has been on my shelf forever and its such a nice looker, I really want to get it airworthy over the winter.

jetmaven

I did something similar some years ago .
Im sure there are a thousand different opinions but for the sake of simplicity I chose a
Clark Y . It's been around forever . Yet to fly and I'm thinking about aerotowing it.
If the picture is upside down , I apologize in advance . When I click on it , it come out right side up.
I give up .

foodstick

Well it looks like your air foil choice works inverted any how ! hahahha

I do like that era of free flight gliders. I can't even imagine the thrill and risk you felt taking something like these up high and just letting them go....

jetmaven

If you click on the picture it opens right side up . I have no idea why but it does .
This design was an updated Albatross .

speedracerntrixie

My Feedback: (29)

Eppler 205 was the go to flat bottom airfoil some 25 years ago. The Airtronics Saggita and Top Flite Antaries both used the 205 and were baseline sailplanes of the era.

BMatthews

I think it becomes a "be careful what you wish for" sort of deal if you modernize it too far.

The whole point of using many of the sailplane airfoils these days is to expand the speed range. But a Super Sinbad fuselage of any sort is a nicely shaped parachute in comparison to the broom handle fuselages used on modern RC sailplanes. So the top end speed is going to be limited by this. Or you'll have to dive so much to make it happen that you lose out.

It's a bit more of a fuss to cover the wing but I'd want to go the other way and use a thin moderately undercambered airfoil to enhance the low speed side of things so it just seems to hang up there. It would become pretty much a light wind sort of model but then the drag of the fuselage sort of sets the bar at that level already.

Also when you say "enlarged" just how much of a size increase are we talking about here?

foodstick

You know, I am not even sure how much the guy I got the plans from enlarged them? This will give you an idea..



I do have a 2 meter Sig riser wing another friend gave me.. maybe I should just strip it, cut it up and make a dihedral wing.., and reshape the tips to a rounder shape....

da Rock

Gentle Lady wing was a good idea. It would have looked different. The Riser wing isn't going to look worse. Rounding the tips would help. However, the original Sinbad had a straight wing, no polyhedral and was not a high aspect ratio at all. So... you got some thinking to do about the wing planform which ever way you go.

Does your present fuselage match up to the root chord of the wing you're planning to use? The aspect ratio of the Sinbad design is quite different from what a Riser/Gentle Lady wing brings to the airplane. In fact, I'd guess truncating the modern wing at the polyhedral break might still give more AR than the Sinbad model had. The yaw stability might be a problem with a 2m wing on that sucker.

da Rock

The E205 actually is a good idea for sure, from experience. I've used it on a straight wing "oldie". Well, it was actually a straight wing with slight LE and TE taper that was E205-E193.

What gave us fits was getting the AOI correct. Incidence seems to have more effect when the wing is carrying a bulky fuselage that probably isn't exactly low drag. I'd suggest having your rear wing rod be adjustable in the fuselage.

foodstick

Hmmm, full flying tail might be smart ....

One change I have made to the fuse was the original plane had the leading edge at the back of the windshield...years ago when I was messing with this I extended the wing saddle to allow the wing to be out forward an inch or two.. right where the windshield comes up in center..

I am really tempted to modify the riser or gentle lady wing as I doubt I would be building/flying two meter anytime soon. I would GUESS the riser wing airfoil is better? the gentle lady wing is my absolute first rc aircraft wing.. I know there is some glue and repair inside of it !

hahahhahaha

I really do want to see this classic bird fly next year. to long on the shelf !