Briggs & Stratton Vanguard 23hp build

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Vigilant1

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What's the thrust difference at say, 30 mph? What's the difference at 100 mph?
Well, if we believe Fred Weik's formula, the difference at 100 MPH is effectively zero. Probably an advantage for the direct drive installation after we subtract the friction losses for the belt drive.

Difference at 30 mph? Dunno. Prop efficiencies at speeds that low are apparently tricky to model, so we'd need to test. But it's a sure bet that the bigger fan will do better at low speeds.

The trikes, UL aircraft, and other kites are using redrives, which makes sense for their airspeed regime.

The OP says he's going to fit this engine to something similar to a DA-11. That plane stalled at 60MPH and probably climbed out at 90 MPH, cruised at a claimed 125 MPH. That doesn't sound like a project that needs a PSRU, and Leeon didn't use one.
 
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Psycho18th

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That's the best way to go, IMO. Accurate and not subject to "helpful', optimistic dyno calibration. You likely know the details, but they are in the attachment here.
Maybe look around for a MakerSpace, Vo-tec school, or a woodworkers club near you to fabricate the clubs? It seems a shame to buy a jointer for this alone (unless you secretly want one anyway!). At the small widths involved, you can probably get by using a jointer, no need for a planer (again, unless you want one anyway.)
Mark
Another option if you are a veteran or know one and near a military base, there’s often a woodshop on base with both a joiner and planer to use for about $5 an hour. Great deal if you can use it.
 

bl_dg

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That's the best way to go, IMO. Accurate and not subject to "helpful', optimistic dyno calibration. You likely know the details, but they are in the attachment here.
Maybe look around for a MakerSpace, Vo-tec school, or a woodworkers club near you to fabricate the clubs? It seems a shame to buy a jointer for this alone (unless you secretly want one anyway!). At the small widths involved, you can probably get by using a jointer, no need for a planer (again, unless you want one anyway.)
Mark
Thanks for the link. I also read the Colomban paper on the Eiffel club testing he did for the Cri Cri. I like it because it's simple, repeatable, and can be duplicated by anyone, anywhere. (And I secretly want a planer anyway!)
 

TiPi

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Thanks for the link. I also read the Colomban paper on the Eiffel club testing he did for the Cri Cri. I like it because it's simple, repeatable, and can be duplicated by anyone, anywhere. (And I secretly want a planer anyway!)
was my excuse as well, and then I made a bunch of small chopping boards as gifts for friends & family and that got me back into the good book :)
 

JuergenA

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Hi friends,
I use a B&S 630 in my SD1 as direct drive and want to improve the power as my next project.
Current are the dates: max cruise speed is is about 100mph at 3600rpm
With the current prop, there is the max rpms at 4500 and this is my destination
with best regards
Juergen
 

Vigilant1

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Hi friends,
I use a B&S 630 in my SD1 as direct drive and want to improve the power as my next project.
Current are the dates: max cruise speed is is about 100mph at 3600rpm
With the current prop, there is the max rpms at 4500 and this is my destination
with best regards
Juergen
Juergen,
Welcome to this forum. The SD-1 is quite an efficient airplane. Still, I've heard others who have the 24hp SE24 (based on the B&S 627) have also found that they want more power (esp if the weights are high, their airport is high or hot, they need a shorter takeoff, etc).
With the present stock propeller at direct drive 4500 RPM, the propeller tips would be above 0.82 Mach. I'm sure you've thought about that. Do you plan to fit a reduction unit (belt drive, etc) to run the prop at lower RPM?

Again, welcome. I know a lot of people will want to hear about your airplane and engine. There aren't many (any?) SD-1 fliers here now (though TiPi is building one). If you want, you could start a thread to show it.

Mark
 
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Air Trikes

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My real experience. Most of the builders were attracted by the "simplicity" of direct drive. Yes, why not if it works for Lycoming and Continental. But in real life, it is not so easy and simple. First - the cranks on real aviation direct drive engines are designed to sustain the direct drive prop loading. The cranks of other engines are NOT designed this way. Second - the propeller becomes noisy and inefficient after approximately 3000 RPM. The belt redrive for low HP engines is simple, cheap, able to provide better performances and longer life of the engine. It helps to raise the thrust line. As a result, real builders of trikes, PPC and light slow (65 MPH and less) planes come to the idea of a redrive at the end. We have such belt drives if somebody is interested.
 

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bl_dg

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My real experience. Most of the builders were attracted by the "simplicity" of direct drive. Yes, why not if it works for Lycoming and Continental. But in real life, it is not so easy and simple. First - the cranks on real aviation direct drive engines are designed to sustain the direct drive prop loading. The cranks of other engines are NOT designed this way. Second - the propeller becomes noisy and inefficient after approximately 3000 RPM. The belt redrive for low HP engines is simple, cheap, able to provide better performances and longer life of the engine. It helps to raise the thrust line. As a result, real builders of trikes, PPC and light slow (65 MPH and less) planes come to the idea of a redrive at the end. We have such belt drives if somebody is interested.
Thanks for all the input, but I’m going with direct drive for my application. The DD-vs-PSRU debate is another topic worthy of it’s own thread. And product pitches should be in the Supplier / Manufacturer Announcements forum.
 

Lucky Dog

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was my excuse as well, and then I made a bunch of small chopping boards as gifts for friends & family and that got me back into the good book :)
Luckily, at least three successful direct-drive conversions of the small-block Vanguard exist that optimized the engine to a specific prop. Why repeat the experiment? Speaking from experience, optimizing a propeller for a low-power engine is expensive and time consuming. Tipi, do you the specs on the Luciole/Vanguard prop?
 

JuergenA

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Hi Mark,
I know the problem about the prop-tips, in attachment, there is my calculation.
I am a fan of Reno and so, it is a must, to go fast ;)
with best regards
Juergen
 

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TiPi

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Luckily, at least three successful direct-drive conversions of the small-block Vanguard exist that optimized the engine to a specific prop. Why repeat the experiment? Speaking from experience, optimizing a propeller for a low-power engine is expensive and time consuming. Tipi, do you the specs on the Luciole/Vanguard prop?
From the Luciole POH (an English translation):

1.4 Motorization
-Engine Briggs and Stratton 627 cc 25 HP at 3600 RPM

1.5 Propellers
-Two-blade Colomban-Arplast D = 1.16 m

2.6 Engine Briggs and Stratton
-Regime never exceed: 4000 RPM.
-Maximum power: use full throttle of the engine, take-off and the rise is limited to 5 minutes (only for potential issues)
-Maximum continuous power: 20 HP (75%) with 3500 RPM
-Fuel: If checked at the lambda sensor, idle (900 RPM) should be rich (1 Volt), cruise plan 3200 to 3300 RPM (0.5 to 0.8 Volt) and full rich gas (1 Volt)

-Maximum temperature:
-Oil 100 °
-EGT 800 °
-Cylinder 130 °
-Normal climb full throttle in the order of 3400 RPM.
 

Air Trikes

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Thanks for all the input, but I’m going with direct drive for my application. The DD-vs-PSRU debate is another topic worthy of it’s own thread. And product pitches should be in the Supplier / Manufacturer Announcements forum.
I am MD aerospace engineer. I fly and build aircraft and engines from 1982, 40 years. My aircraft is FAI World and Euro Champion for several last years. I wanted to share my real experience, maybe save your time and efforts. If you think my post is nothing but "product pitches", I apologize and wish to remove it.
 

Vigilant1

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Hi Mark,
I know the problem about the prop-tips, in attachment, there is my calculation.
I am a fan of Reno and so, it is a must, to go fast ;)
with best regards
Juergen
Juergen,
If the wooden blades stay intact, you'll still have unhappy neighbors. They'll be waiting for you to land with their pitchforks and torches.;)
Best wishes,
Mark
 
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cluttonfred

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I am MD aerospace engineer. I fly and build aircraft and engines from 1982, 40 years. My aircraft is FAI World and Euro Champion for several last years. I wanted to share my real experience, maybe save your time and efforts. If you think my post is nothing but "product pitches", I apologize and wish to remove it.

Vassili, please don't do that, we value your experience and input.
 
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I am MD aerospace engineer. I fly and build aircraft and engines from 1982, 40 years. My aircraft is FAI World and Euro Champion for several last years. I wanted to share my real experience, maybe save your time and efforts. If you think my post is nothing but "product pitches", I apologize and wish to remove it.
I, for one, read every word you post. please do not stop.
 
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