Bronco Type XXIII in 1/35th scale

[redboat219]

Think David has already tried that.

Maybe time to try flow visualization around the bow using cotton thread. There's something there generating negative lift.

[He Who Shall Not Be Named]

Sir,
Is it possible that the water ingested by the open shutter doors is being expelled out of the stern free flood holes on the bottom of the boat thus causing the stern to rise when at full speed?

Yes, that's what I was thinking too. But, after putting tape around the shutter door opening and finding no change, I can now discount that as the cause of the pitch-down problem. Good thinking though.

M

[jim h]

Hello David , I took the Apc out of my XXIII along time ago after fighting this problem . You have seen mine run at Carmel ,I set the rear planes on full up and front at half dive angle and she will run at level depth all day . I never move rear and only use front when on surface . Just a idea .


Jim H.

[trout]

So, is it the large sail causing the issue? As you increase the speed it creates a larger drag forcing the bow up? But others with Type XXIII have it working o.k. - mine does not go fast, but does dive and stay level with no adjustments. Once it gets out of dry docks (again) I will run it at a faster speed.
David, I am sorry you are going through this, but selfishly, I am learning from your experience and the great suggestions.
Peace,
Tom

[He Who Shall Not Be Named]

Hello David , I took the Apc out of my XXIII along time ago after fighting this problem . You have seen mine run at Carmel ,I set the rear planes on full up and front at half dive angle and she will run at level depth all day . I never move rear and only use front when on surface . Just a idea .


Jim H.

No ****!??.... So, I'm not crazy.

I will try that tonight, you nasty old model-builder, you!

Film at Eleven.


David

[He Who Shall Not Be Named]

So, is it the large sail causing the issue? As you increase the speed it creates a larger drag forcing the bow up? But others with Type XXIII have it working o.k. - mine does not go fast, but does dive and stay level with no adjustments. Once it gets out of dry docks (again) I will run it at a faster speed.
David, I am sorry you are going through this, but selfishly, I am learning from your experience and the great suggestions.
Peace,
Tom

Darrin's observation is the best thing I've heard yet -- I have an immense respect for this guys work and place great value on anything he says.

(That's the build-up ... now, if his suggestion does not work, I will vilify him horribly tonight when I report back on the results. No good deed goes unpunished here!).

M

[ffr2608]

What do I get if it works? I like cash and round polycarbonate tubes.........
I never drive from the rear. This is no forklift.

Lead it from the front and the rear planes keep it level.

Darrin

[He Who Shall Not Be Named]

My never ending gratitude and one bucket of water-slug.

Tomorrow -- been too busy to try out your idea, Darrin. Can't wait.

M

[redboat219]

Curious,

In your previous post the c.g. is located in front of the sail. That's where i assume the center or rotation would also be located. So forces acting on the sail would cause the bow to pitch up not down.

[ffr2608]

This period of silence has me a bit worried.


D

[He Who Shall Not Be Named]

held up in the Cave catching up on purchase orders.

M

[GNuge]

My thoughts on your pitch control issue . Is it possible that the boat is leaning wh

[QUOTE=He Who Shall Not Be Named;28504]held up in the Cave catching up on purchase orders.

Sir, is it possible that your boat is leaning to one side or the other while turning at speed and the rudder is then acting similar to the stern planes to cause the boat to dive or rise depending upon which way it is leaning?

[He Who Shall Not Be Named]

Good point, and a real phenomena, but only occurs as a consequence of 'foil-roll'. The sail acting as a centerboard at a high angle-of attack, inducing the boat to roll into a tight turn. Big issue with high performance submarines -- but something compensated for by a good ship-control party: with little direction the planesman and helmsman will coordinate to put on some up plane to counter the pitch-down force produced by the rudders as they orient away from the vertical with the roll.

But, that's not the issue with the submerged tests with the 23. The pitch-down is occurring while going straight ahead. No turn, no foil-roll.

Good thinking though.

M

[GNuge]

Hello David,

Is it possible that the bronco models lack of negative angle on the stern fins is causing the pitch problem? My old 32 parallel type 23 has negative angle moulded into the thin airfoil shaped fins in front of the stabilizer and this boat is stable at all speeds. Then again it is not fast! Most photos indicate this negative angle and the Fritz kohl plans also show it. Food for thought. Good luck.
Sincerely,

george

[He Who Shall Not Be Named]

Hello David,

Is it possible that the bronco models lack of negative angle on the stern fins is causing the pitch problem? My old 32 parallel type 23 has negative angle moulded into the thin airfoil shaped fins in front of the stabilizer and this boat is stable at all speeds. Then again it is not fast! Most photos indicate this negative angle and the Fritz kohl plans also show it. Food for thought. Good luck.
Sincerely,

george

Don't know if the BRONCO Type-23 has the incidence on the stabilizers (actually their function is to act as cut-waters, protecting the control surfaces from contact damage) to scale with prototype or not. Drawings I've seen seem to have the cord of those surfaces parallel with the boats centerline. On the kit they are (both the fore and after sets) at a zero-degree incidence, which strikes me as proper.

Anyway ... after weeks of getting caught up on Caswell work, I took Darrin's advice and switched the angle-keeper to the bow planes and are now driving the stern planes manually -- only employing them as a set of trim surfaces. That's how Darrin got his Type-23 kit to perform underwater.

Tomorrow is the Elite Fleet's outing at the Norfolk Nauticus Coy ponds. I'll evaluate the new control set-up then and will report back on how it worked over the weekend.

M