BUILD THREAD: Sig RISER-100 wing on Topmodel PRELUDE fuselage

[G-man]

Cloudy day first flight.
Thanks, JOH, for making the photos.

 

[Sandman]

Looking good Dave
The graphics really stand out
With the Riser wing, and stock Prelude rudder, did it feel like it had enough rudder authority?

Don

 

[G-man]

Don,
Plenty of rudder and elevator authority with the OEM parts. No worries there.
Man-o-man it really floats on that wing. No wonder it has been in production for 35 years.
Two flights with two battery pack weights, but I have not found the exact right balance point yet.
That and fine-tuning the control throws, then ready for flight test description.
I also want to assess the visibility of the covering scheme in the sunlight. Works pretty good on the gray day.
// Dave

 

[Wayne]

Looks great on the grey day!

 

[G-man]

Got some sun today. Flew it on a blue sky day finally.
CG at 87 mm (3mm in front of suggested range.)
Lovely hands-off level flight, but dive test indicates still tends toward tail heavy.
I did not let it get fast in the dive test this time.

Thank you Jeremy for your work behind the camera.
// Dave

 

[Wayne]

Dave - I was thinking about this and wonder if you might be willing to try something? I think you have way to much battery on these planes. With the rather heavy motor and battery combo, I think you are setting yourself up for flutter in models that have not fluttered for you in the past.

Since you have an "outrunner in a can" motor, don't be afraid to run a smaller battery and place lead up and round that motor to hit CG. Getting the mass as far forward as possible should greatly reduce the AUW of the model.

The weight reduction should result in a model that flies much better and needs a lot less motor, and we know, less motor means less battery needed. It could be a winning combination. Your flight times may actually increase despite a much smaller battery capacity.)

Please replace the 3S 3300 with something like a 3S 1300 and nose lead. (Woods metal is great for this sort of thing, I can melt the stuff with a covering iron! Just don't get any in the motor.)

I'd like to build one of the AH-100 wings with the Fuselage from the Harpia and power it with a rather light and low powered motor with maybe an 850 mah battery. Should be a real floater with that setup.

 

[G-man]

Wayne,

> I was thinking about this and wonder if you might be willing to try something?

Sure, I will try reducing the weight and moving the remaining weight as far forward as possible.
- I have a shorter, lighter outrunner-in-a-can motor I can install.
- I have roofer's lead sheet which will form easily around the motor.
- I have smaller capacity battery packs to try.

>I'd like to build one of the AH-100 wings with the Fuselage from the Harpia and power it with a rather light
>and low powered motor with maybe an 850 mah battery. Should be a real floater with that setup.

A very cool experiment.
I do like the idea of planes that will float like a butterfly, dance like a ballerina.

// Dave

 

[Sandman]

With a 3S 1300, for leisurely climb, what size motor/prop combo would it take to get the job done.

Don

 

[Wayne]

What is your estimated AUW? We can run some numbers and make a motor suggestion for you.

There is a wide range of possible motors for this plane. With a "gas bag" wing we aren't going to be going fast, so might as well set it up so we can spend most of our time without running the motor. If this sounds like the type of flying you would like to do, then a lower powered setup should be a good choice. But if you like to keep the prop spinning, and like to climb aggressively at times, then a more powerful setup would be your ideal.

I tend to like my "gas bag" gliders with less power. I'm pretty happy at anything over 30 degree climb angle and my motor and battery will weigh a fraction of the typical setup people select. This is just for recreational flying. This low a power setup will result in a large weight savings.

With this said, I think the Prelude fuselage has a rather short nose, so nose weight will probably be mandatory when running a lighter setup. But we should still see performance gains with the lighter setup, and landings should be much lower energy affairs so our planes should last a lot longer.

 

[Sandman]

Dave's Riser 100 came in at 29.5 ounces AUW, which I thought was decent.
If the new wing design weight comes in less than the Riser wing, and with marginal motor and battery
components, this weight reduction would be considerable.

 

[G-man]

Wayne> Please replace the 3S 3300 with something like a 3S 1300 and nose lead.

Plan to remove and replace onboard gear to lighten the airframe.

BEFORE (balances at 88 mm from LE)

Gliderdrive 4.6 motor 181 g
Turnigy 40 amp ESC 38 g
Gens Ace 4S 2200 mAh 236 g
TOTAL 455 g


AFTER (proposed lighter gear from available in stock)

Gliderdrive 3.5 motor 139 g
Mantis 25 amp ESC 26 g
Jeti 32 1800 mAh 121 g
TOTAL (no lead yet) 286 g

It's unknown how much lead I'll have to add for balance.
I don't have a 1300 pack, but the Jeti 1800 is pretty small and light.

I'll report that number, and finish the flight report when I get the gear mounted and get some flight testing done.

 

[Wayne]

Yeah, that 1800 is light. This should be interesting.

I thought you were flying a 3S 3300 battery?

 

[Red]

Dave you mentioned earlier that it was tending towards tail heavy in a dive test, was it tucking? This has been a fun project to watch.

 

[G-man]

Dave you mentioned earlier that it was tending towards tail heavy in a dive test, was it tucking? This has been a fun project to watch.

Red,
Yes, exactly so.
While it would trim nicely for straight and level flight, in the dive test it would speed up quickly and begin to tuck under.
This is particularly a mystery to me because my last RISER-100 wing on the PRELUDE fuse was wonderfully well behaved.
Unfortunately, that's the one (red clear covering) that I flew OOS in the Canadian wildfire smoke and haze.
// Dave

 

[Red]

Red,
Yes, exactly so.
While it would trim nicely for straight and level flight, in the dive test it would speed up quickly and begin to tuck under.
This is particularly a mystery to me because my last RISER-100 wing on the PRELUDE fuse was wonderfully well behaved.
Unfortunately, that's the one (red clear covering) that I flew OOS in the Canadian wildfire smoke and haze.
// Dave

Full flying tail?

 

[G-man]

Yes, full flying horizontal.
That's supposed to handle this problem for us, right?
Things that make us go "Hmmmmm."

 

[G-man]

Crash, and Crash Again

Wayne> I thought you were flying a 3S 3300 battery?

For three previous days of flying, yes, a 3S 3300 battery pack.
But as a trial to reduce tail heaviness on Tuesday this week I grabbed the 2200 4-cell monster. It's a hefty one.
This practice, of course, moves in the opposite direction from what you are suggesting I try.
And it leads to a confession. I crashed twice in three launches on Tuesday.

First launch and landing: A-OK
Dive test showing some tuck under, but not as much as previously.
Moved the battery pack half an inch forward, snug to the back of the motor.

Second launch, flying for the camera - turned while too low and slow and piled in from 20 feet.
Broke one nylon bolt, no other damage observed.
Replaced the bolt and relaunched.

Third launch, flying for the camera again, but trying to be more attentive.
Even so, I got too low and slow with the heaviest 100-inch floater I've ever flown and piled in again.
This time broke both nylon bolts, a folding propeller blade, and knocked the servo mounts loose.

OK, done for the day with that plane, but here's the important point:
NO DAMAGE AT ALL TO THE TOPMODEL PRELUDE FUSELAGE.
NONE.
NONE AT ALL.
Even under very careful inspection on the bench today, not one bit of damage can be found.

It took me 48 hours of pondering to decide to admit this online.
I do not mention this to showcase my meager flying skills and poor judgement.
I do it to assure builders that the Topmodel PRELUDE supplies a TOUGH FUSELAGE.

For the balsa bashers among us who have seen split, crushed and fractured fuselages, be not afraid of a FIBERGLASS fuselage.
This fuse is stronger than you'd think.

Keep on Rockin' guys.
// Dave

 

[Wayne]

Interesting. Did the plane roll over or anything to cause the crash?

If tail heavy and you let it get too slow, it might hold the nose up too long and cause a rather deep stall. Does this sound like what you experienced?

 

[G-man]

No roll over.
Deep stall yes.

 

[Red]

Yes, full flying horizontal.
That's supposed to handle this problem for us, right?
Things that make us go "Hmmmmm."

Well, it takes incidence out of the question for sure.