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Search: Posts Made By: Marc Bourget
Forum: RV Building Tips/Techniques 03-16-2019, 11:41 AM
Replies: 13
Views: 767
Posted By Marc Bourget
If you are speaking of standard AD rivets, I...

If you are speaking of standard AD rivets, I would look first to your dimpling technique.

When I first started, wary of the "softness" of the Alu, I was always under forming the dimple. You have...
Forum: RV General Discussion/News 02-24-2019, 08:26 AM
Replies: 11
Views: 834
Posted By Marc Bourget
I'm curious about this as I didn't think much in...

I'm curious about this as I didn't think much in the way of volume flows through the Pitot "side". Maybe the static because of some instrument bleed, but I wonder if "design" or "configuration" of...
Forum: RV-4 02-09-2019, 08:08 AM
Replies: 24
Views: 2,177
Posted By Marc Bourget
Check and then monitor your temps. Don't get too...

Check and then monitor your temps. Don't get too high. Once it flows well, stabilize the heat
Forum: RV-10 02-07-2019, 08:23 AM
Replies: 13
Views: 1,263
Posted By Marc Bourget
Point to ponder. The struts and seals are...

Point to ponder. The struts and seals are purposed application - unlike accessories selected from catalogs or copied from this forum.

Not weighing in one way or the other, just adding...
Forum: Safety 02-04-2019, 09:17 AM
Replies: 47
Views: 3,848
Posted By Marc Bourget
All well and good but survivability is increased...

All well and good but survivability is increased by more attention to restraints.

I recall a 78 yr old lady who expired in a relatively low speed auto accident because of Atherosclerosis. The...
Forum: RV-4 01-29-2019, 08:44 AM
Replies: 4
Views: 523
Posted By Marc Bourget
Talking Quick rule of thumb for future reference - for...

Quick rule of thumb for future reference - for the less knowledgeable.

Breakers sized for (to protect) the conductor.

Conductors are sized for the load.

Why the difference here?

Motors have a...
Forum: RV-7/7A 01-27-2019, 10:07 AM
Replies: 13
Views: 1,513
Posted By Marc Bourget
Bill, Was there a reason, besides aesthetics, to...

Bill,

Was there a reason, besides aesthetics, to using flush rivets?
Forum: Propellers 01-27-2019, 10:03 AM
Replies: 71
Views: 12,918
Posted By Marc Bourget
Can you provide a fairly accurate measurement of...

Can you provide a fairly accurate measurement of the position of the crack in relation to the overall length of the blade (and in respect to the length outside of the hub) ?

Wonder if the crack...
Forum: RV-8/8A 01-02-2019, 01:14 PM
Replies: 50
Views: 13,811
Posted By Marc Bourget
Proper design of an Augmenter Tube - one factor...

Proper design of an Augmenter Tube - one factor is sufficient length that an exhaust pulse is still in the tube when the next cylinder's pulse enters the Augmenter Tube, denying a chance for reverse...
Forum: Traditional Aircraft Engines 12-22-2018, 03:29 PM
Replies: 230
Views: 115,670
Posted By Marc Bourget
Dan asked: "Can you tell us how the proposed...

Dan asked: "Can you tell us how the proposed test might be conducted, why, and what might be determined?"

Don, I apologize for not responding directly to this earlier.

John Thorp and I also...
Forum: Traditional Aircraft Engines 12-21-2018, 12:51 PM
Replies: 230
Views: 115,670
Posted By Marc Bourget
Dan, I was speaking from the recollection of a...

Dan,

I was speaking from the recollection of a series of discussions (more literally lectures) by John Thorp. The particular point discussed were his cooling drag studies (or FAA flights) related...
Forum: RV-4 12-19-2018, 04:12 PM
Replies: 4
Views: 825
Posted By Marc Bourget
Are the particular panels removable and do you...

Are the particular panels removable and do you have access to a bead roller?
Forum: Traditional Aircraft Engines 12-17-2018, 08:12 AM
Replies: 230
Views: 115,670
Posted By Marc Bourget
Wouldn't the "test" for whether an inlet was too...

Wouldn't the "test" for whether an inlet was too large be glide/tuft testing different inlet sizes ?
Forum: RV-7/7A 12-08-2018, 11:16 PM
Replies: 3
Views: 631
Posted By Marc Bourget
I was taught by guys who worked in the prototype...

I was taught by guys who worked in the prototype shops for Lockheed and North American. For something straight like a wing panel or the HS, Consider attaching two 3/4" extruded angles Cleeco them...
Forum: RV General Discussion/News 12-08-2018, 01:00 PM
Replies: 2
Views: 1,146
Posted By Marc Bourget
Could it be that your forward (ground) speed was...

Could it be that your forward (ground) speed was close to his - making it appear, relative to you, that he was raising "vertical"???

:)
Forum: Midwest 12-07-2018, 07:15 AM
Replies: 18
Views: 4,189
Posted By Marc Bourget
My understanding is that if you are negligent or...

My understanding is that if you are negligent or make a non-intentional mistake in preparing/paying your tax return. . .

the statute of limitations runs from the time you file/pay your taxes.

If...
Forum: My RV Build Project 10-18-2018, 11:08 PM
Replies: 16
Views: 2,401
Posted By Marc Bourget
Nitro, I've volunteered at the OSH 1/2 day...

Nitro,

I've volunteered at the OSH 1/2 day workshops and one weekend workshop and done sheetmetal forums at Sun'nFun.

While you will learn some processes and will get familiar with riveting, etc., ...
Forum: RV-10 10-13-2018, 07:41 PM
Replies: 18
Views: 1,482
Posted By Marc Bourget
It's the inlet edge that's perpendicular to...

It's the inlet edge that's perpendicular to airflow. The "corners" where the curved side edges is 90 deg.

FWIW
Forum: RV-10 10-09-2018, 07:57 AM
Replies: 18
Views: 1,482
Posted By Marc Bourget
To obtain the design benefit of a NACA scoop you...

To obtain the design benefit of a NACA scoop you should put it in an area where the fuselage cross-section is increasing. Also pay attention to the "bar" across the aft end of the opening. Proper...
Forum: RV-12/RV-12iS 08-07-2018, 09:36 PM
Replies: 6
Views: 1,977
Posted By Marc Bourget
Those speeds are also dependent on weight. It...

Those speeds are also dependent on weight. It might be worthwhile to investigate the effect weight makes in your initial test period(s)
Forum: RV Ongoing Maintenance Issues 07-22-2018, 02:00 AM
Replies: 12
Views: 1,502
Posted By Marc Bourget
With car engines, one technique is using...

With car engines, one technique is using starting fluid, small careful doses, but the fan on a car is much smaller and protected.

Just looking maybe should be expanded into some careful...
Forum: Traditional Aircraft Engines 07-15-2018, 08:17 PM
Replies: 11
Views: 1,663
Posted By Marc Bourget
With the piston at the bottom of its stroke, the...

With the piston at the bottom of its stroke, the pressures are minimal.

As the factory says, size it for the top end where the "work" is done!
Forum: RV-14 07-15-2018, 11:17 AM
Replies: 8
Views: 1,648
Posted By Marc Bourget
The "bow" occurs because of the compression of...

The "bow" occurs because of the compression of material inside the neutral axis of sheet (when looking on edge.) from bending the material.

It can (as suggested) be pulled into line, or you can use...
Forum: RV General Discussion/News 06-30-2018, 11:15 AM
Replies: 15
Views: 2,252
Posted By Marc Bourget
These results have been reported many times,...

These results have been reported many times, since the NACA studies during WW-II. That being said, I compliment you on the effort! Unusual and laudatory! Good Man!

I do have concerns with the...
Forum: Electrical Systems 06-30-2018, 09:47 AM
Replies: 20
Views: 2,683
Posted By Marc Bourget
My comment about operating altitudes came from a...

My comment about operating altitudes came from a conversation with an actual engineer buried in the back- shop of Plane Power.

I recall two points of interest, rpm and brushes. After further...
Forum: Electrical Systems 06-28-2018, 11:57 PM
Replies: 20
Views: 2,683
Posted By Marc Bourget
You don't plan to fly over about 6000 ft? :D:):D

You don't plan to fly over about 6000 ft?

:D:):D
Forum: RV General Discussion/News 06-26-2018, 08:45 PM
Replies: 19
Views: 3,315
Posted By Marc Bourget
Like the emphasis on rivet gun control. Direct...

Like the emphasis on rivet gun control. Direct and to the point.

The majority of the previous were all good hints, but gun control was not stressed.

I solo riveted wings on another design that had...
Forum: Propellers 06-22-2018, 05:35 PM
Replies: 5
Views: 1,019
Posted By Marc Bourget
John, Thanks for the picture, but I'd like to...

John,

Thanks for the picture, but I'd like to see a view from a step back.

Is is possible to "color" the cracked areas with a sharpie and wipe clean for more contrast?

Thanks
Forum: Traditional Aircraft Engines 05-28-2018, 04:25 PM
Replies: 9
Views: 1,060
Posted By Marc Bourget
See if you can get access to an ultrasonic...

See if you can get access to an ultrasonic cleaner of sufficient size.

Not guaranteed, but it will do better than simple flushing/reverse flushing.

There was an article in Kitplanes some years back...
Forum: RV General Discussion/News 05-24-2018, 07:34 AM
Replies: 2
Views: 791
Posted By Marc Bourget
I do not recall the placement point. I believe...

I do not recall the placement point.

I believe there are plenty of other factors that prevent laminar flow that far back on the (any) fuselage.

The slipstream is generally at ambient pressure as...
Forum: RV-14 05-06-2018, 12:29 PM
Replies: 20
Views: 3,918
Posted By Marc Bourget
Smile Good to be cautious, but how is that rib loaded...

Good to be cautious, but how is that rib loaded when in use?

It mainly serves in compression and I don't think much stretch or bending takes place in the vicinity of the deformation.

I'd lightly...
Forum: RV-8/8A 05-05-2018, 08:10 AM
Replies: 20
Views: 3,932
Posted By Marc Bourget
I believe there is much more dynamic pressure...

I believe there is much more dynamic pressure possible than "lift" from slipstream airflow.
Forum: RV-8/8A 05-03-2018, 05:29 AM
Replies: 16
Views: 4,414
Posted By Marc Bourget
It's not black magic. I watched an industrial...

It's not black magic. I watched an industrial arts teacher, (Don Pridham, author of the GPU Conversion book), laminate some plywood, drill holes for a home-made vacuum table, and, with a canister...
Forum: RV General Discussion/News 04-25-2018, 02:24 PM
Replies: 26
Views: 4,217
Posted By Marc Bourget
First, I'm away from my reference material. I've...

First, I'm away from my reference material.

I've seen many installations where the mass flow to the cooler is choked off by a long SCAT hose, or other things that defeat flow.

Have you checked the...
Forum: RV-8/8A 04-18-2018, 08:31 AM
Replies: 50
Views: 13,811
Posted By Marc Bourget
Tom said: " I have no proof, but I feel that if...

Tom said: " I have no proof, but I feel that if you get your outlet air flow in the right direction, the outside air may even help to pull the air out."

It doesn't, as there's nothing between the...
Forum: Alternative Engines 04-09-2018, 05:24 PM
Replies: 45
Views: 7,699
Posted By Marc Bourget
I looked at the Eggenfelder efforts some years...

I looked at the Eggenfelder efforts some years ago and inspected his efforts at OSH and a local Sonex owner. One question Jan refused to answer was what investigation he made into modifications...
Forum: RV Building Tips/Techniques 04-06-2018, 03:11 PM
Replies: 9
Views: 1,353
Posted By Marc Bourget
Lot's of good points, above. I think I spent an...

Lot's of good points, above. I think I spent an average of 15 minutes or so just on riveting in my Sun'nFun and Air Venture sheet metal forums. So many points popped into my mind reading this...
Forum: RV General Discussion/News 03-27-2018, 05:39 AM
Replies: 19
Views: 1,837
Posted By Marc Bourget
Talking Check the spec sheet to verify from what surface...

Check the spec sheet to verify from what surface or plane you measure the length of a flush vs. brazier head rivet :D
Forum: Traditional Aircraft Engines 03-26-2018, 02:15 PM
Replies: 13
Views: 1,914
Posted By Marc Bourget
Michael, I think he meant moving the ramp a...

Michael,

I think he meant moving the ramp a short distance away from the cylinder (at about the midline of the cylinder?) but I believe he kept the baffle tight towards the "6 O'Clock" position or...
Forum: RV General Discussion/News 03-19-2018, 09:17 AM
Replies: 11
Views: 1,335
Posted By Marc Bourget
Didn't remember this when I first viewed the...

Didn't remember this when I first viewed the thread.

A definitive NACA Cooling report described placing something like 34 Thermocouples on the downstream side of the cylinder. Interesting but...
Forum: RV General Discussion/News 03-15-2018, 08:07 AM
Replies: 10
Views: 1,970
Posted By Marc Bourget
Bill, If you meet the pressure differential...

Bill,

If you meet the pressure differential specs for the engine, you should get the necessary mass flow.

As far as inlet size, if properly designed you should experience little, if any, increase...
Forum: RV General Discussion/News 03-09-2018, 08:13 PM
Replies: 13
Views: 1,983
Posted By Marc Bourget
Talking That might be an "apples vs. oranges" point, but...

That might be an "apples vs. oranges" point, but I agree yours is a more accurate technical description.

There was a "How it's Made" episode that described submersing formed ribs in a salt bath as...
Forum: RV General Discussion/News 03-09-2018, 07:10 PM
Replies: 13
Views: 1,983
Posted By Marc Bourget
The benefit to be gained from “icebox rivets”...

The benefit to be gained from “icebox rivets” (2024) is achieved when you alter (expand) the rivet spacing to take advantage of their greater strength. Almost irrelevant in structure designed for...
Forum: RV-7/7A 03-04-2018, 06:25 PM
Replies: 5
Views: 1,085
Posted By Marc Bourget
I think you can go larger than 2.2" if you design...

I think you can go larger than 2.2" if you design the intake opening correctly, Same as for cooling intake.

With engine intake, a superior installation would have a smooth intake duct with...
Forum: RV-7/7A 03-04-2018, 06:20 PM
Replies: 6
Views: 999
Posted By Marc Bourget
I think it is easy to assume the baffles are...

I think it is easy to assume the baffles are identical by appearance, but are they identical in Delta-P?

Hook up a manometer to each and verify they perform the same.
Forum: Interiors 02-27-2018, 08:50 AM
Replies: 22
Views: 5,592
Posted By Marc Bourget
I recall an article about sound proofing. The...

I recall an article about sound proofing. The author installed sensors in all the panel areas (between bulkheads and stringers for example) turned out just a few panels generated the majority of...
Forum: RV-14 02-13-2018, 08:05 AM
Replies: 20
Views: 2,503
Posted By Marc Bourget
IMHO, the differing amount of gap is a result of...

IMHO, the differing amount of gap is a result of incomplete execution of the "dimpling process." Technically, between the upper and lower skins when joining sheets and a special angle (110 deg)...
Forum: RV-14 02-12-2018, 08:37 AM
Replies: 20
Views: 2,503
Posted By Marc Bourget
Keep in mind, "so it lays flat" means no more...

Keep in mind, "so it lays flat" means no more than .002" between the countersunk member and the dimpled skin."
Forum: Traditional Aircraft Engines 02-06-2018, 07:58 PM
Replies: 13
Views: 1,877
Posted By Marc Bourget
The 4130 part was a safety piece. If the flange...

The 4130 part was a safety piece. If the flange failed, it kept the propeller with the aircraft. The spacer was used to stiffen the flange as an assembly with the intent of not needing the safety...
Forum: Traditional Aircraft Engines 02-05-2018, 05:51 PM
Replies: 13
Views: 1,877
Posted By Marc Bourget
The 0-290G the Lycoming GPU had a thin flange...

The 0-290G the Lycoming GPU had a thin flange because all it had to do was drive a pretty much immovable alternator.

When John Thorp started converting the GPU for the T-18 project he advised...
Forum: RV Building Tips/Techniques 11-25-2017, 09:02 AM
Replies: 20
Views: 3,035
Posted By Marc Bourget
Slightly swelling a rivet is helpful in assembly...

Slightly swelling a rivet is helpful in assembly when skins (particularly "formed" shikns) don't fit "exactly."

You can either pre-swell, or insert and "swell" (takes practice). Then follow up by...
Forum: RV-7/7A 11-25-2017, 08:54 AM
Replies: 17
Views: 3,557
Posted By Marc Bourget
I'd do some dimples in a piece of scrap and see...

I'd do some dimples in a piece of scrap and see how they "fit" in the CS.

Should be less than .002" between the skin and spar. (If more, too shallow of a C/S. If it "slides" or "wiggles" C/S is...
Forum: Traditional Aircraft Engines 09-29-2017, 01:30 AM
Replies: 18
Views: 3,294
Posted By Marc Bourget
An unmentioned issue is what is the proper way to...

An unmentioned issue is what is the proper way to check the crank.

A friend of mine is a long time auto engineer. He was on several initial design team for new OEM engines in Detroit.

The...
Forum: RV-14 07-05-2017, 11:09 PM
Replies: 8
Views: 1,805
Posted By Marc Bourget
No smilies when you keep things under control and...

No smilies when you keep things under control and in alignment. (i.e., if you don't over-drive)
Forum: RV-10 06-04-2017, 10:16 AM
Replies: 4
Views: 797
Posted By Marc Bourget
I was taught, (and teach in my sheet metal...

I was taught, (and teach in my sheet metal seminars) by men who'd learned their trade in the WW-II factories in So Cal that if you're matching parts, you drill holes with a 1/8" or .125 drill, at,...
Forum: RV-7/7A 05-01-2017, 07:46 AM
Replies: 22
Views: 5,053
Posted By Marc Bourget
Will somebody favor me by posting a picture of a...

Will somebody favor me by posting a picture of a "pillow effect"?
Forum: RV General Discussion/News 04-24-2017, 10:23 AM
Replies: 32
Views: 4,753
Posted By Marc Bourget
I like to cover my benches with the "original"...

I like to cover my benches with the "original" Astro-turf, not the carpet "grass".
Forum: RV General Discussion/News 04-24-2017, 10:13 AM
Replies: 1
Views: 862
Posted By Marc Bourget
Although some would venture there are as many...

Although some would venture there are as many approaches as aircraft, at some point, the baffles are best placed in contact with the fins, although some use high temp adhesive to reduce chafing,...
Forum: RV General Discussion/News 04-24-2017, 10:09 AM
Replies: 8
Views: 2,349
Posted By Marc Bourget
I agree, but considering the external...

I agree, but considering the external environment and the fact that the relatively low pressure in the bottom half of the cowl and low flow volume from the hinge gaps is faint by comparison with jet...
Forum: RV General Discussion/News 04-23-2017, 09:47 AM
Replies: 8
Views: 2,349
Posted By Marc Bourget
Wonder if it's significant enough to worry about....

Wonder if it's significant enough to worry about. Seems the helical airflow from the propeller will cause more turbulence/drag than leakage from the cowl hinge.

Second thing is I do not believe...
Forum: RV General Discussion/News 04-23-2017, 09:42 AM
Replies: 32
Views: 4,753
Posted By Marc Bourget
You guys are missing a technique to fix a "factor...

You guys are missing a technique to fix a "factor " only a few pointed out.

You have to get some movement of the skin in order to drive the rivet. This will often lead to a depression like...
Forum: RV Ongoing Maintenance Issues 04-18-2017, 10:00 AM
Replies: 11
Views: 2,796
Posted By Marc Bourget
You have nothing to lose, Don't think the gear...

You have nothing to lose, Don't think the gear is heat treated. Why not try bringing the ring gear up to a dull red heat and let it cool to see if it will "heat shrink" enough to tighten up and...
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