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[hpergm]

��ðùò �ôóé èá ã�íåé Äçì�ôñç.

�é ð�íù â�äåò èá ðñüóâáóç áðü ôï gun hood (ôï ïðï�ï âãá�íåé �îõðíá �áé åý�ïëá ìå ìáãíçô��éá). �á ìðå� áëïõìéí�íéá ãùíé� �áé èá ôï âéäþíïõìå áí�ðïäá (áðü ð�óù, ìå blind nuts ð�íù óôï cowl ring áíô� ãéá ôï firewall ôþñá). Ôï �÷ïõí ��íåé �ôóé áñ�åôï� óôá î�íá forums.

Ãéá ôéò Γ�Γ�ôù üðïõ Γ¥Γ�íáé Γ�áé ôï ìåãáëýôåñï ðñüâëçìá, Γ³Γ�åöôüìáóôå ôï åîΓ�Γ²: Γ­Γ΅ ôïðïèåôΓ�óïõìå ìüíéìá óôïí åìðñüóèéï ìðïõëìΓ� ôçò Γ³Γ�ëáò 2 ΓΆΓ�äåò ðïõ èá ðñïåΓ�ôåΓ�íïíôáé ðñïò ôï cowl, Γ�áé èá ìðáΓ�Γ­Γ―ΓµΓ­ Γ¬Γ�Γ³Γ΅ Γ³Γ¥ ìðëüΓ�éá îýëéíá (ìå ìåôáëëéΓ�ΓΌ Γ³ΓΉΓ«Γ�Γ­Γ΅ ΓΉΓ² insert) Γ�ïëëçìΓ�Γ­Γ΅ Γ°Γ�Γ­ΓΉ óôï cowl ring. Ôï üëï óýóôçìá èá áóöáëΓ�æåé ìå Γ³Γ�ïõëéΓ�üâéäåò (óðåΓ�ñùìá Γ°Γ�Γ­ΓΉ óôá ìðëüΓ�éá, Γ°Γ�ôçìá Γ°Γ�Γ­ΓΉ óôéò ðñïåΓ�ôåéíüìåíåò ΓΆΓ�äåò) Γ¬Γ�Γ³ΓΉ 2 ìéΓ�Γ±ΓΎΓ­ ôñõðþí óôï cowl ãéá Γ­Γ΅ ìðáΓ�íåé áëëåíüΓ�ëåéäï. Γ‹Γ�ìå ôþñá..  

[w1ndsurfer]

¸�ôùñá
Öôé�îå ìéá óùë�íá ìå äé�ìåôñï ë�ãï ìåãáëýôåñç áðü ôçí �åöáë� ôçò â�äáò, íá öô�íåé ì�÷ñé ôï baffle. Ãéá íá ìçí öá�íåôáé ç ôñýðá óôï baffle â�æåéò ìåô� ìéá ô�ðá.
� óùë�íáò ìðïñå� íá å�íáé áðü ôõëéãì�íï ÷áñô� åíéó÷õì�íï ìå �õ�íï � epoxy.

�å ôçí óùë�íá óáí ïäçãü, ìå �íá ìá�ñý �áôóáâ�äé âéäþíåéò-îåâéäþíåéò ÷ùñ�ò íá ÷ñåé�æåôáé íá âë�ðåéò ôçí �åöáë� ôçò â�äáò.

[hpergm]

¸�ôùñá
Öôé�îå ìéá óùë�íá ìå äé�ìåôñï ë�ãï ìåãáëýôåñç áðü ôçí �åöáë� ôçò â�äáò, íá öô�íåé ì�÷ñé ôï baffle. Ãéá íá ìçí öá�íåôáé ç ôñýðá óôï baffle â�æåéò ìåô� ìéá ô�ðá.
� óùë�íáò ìðïñå� íá å�íáé áðü ôõëéãì�íï ÷áñô� åíéó÷õì�íï ìå �õ�íï � epoxy.

�å ôçí óùë�íá óáí ïäçãü, ìå �íá ìá�ñý �áôóáâ�äé âéäþíåéò-îåâéäþíåéò ÷ùñ�ò íá ÷ñåé�æåôáé íá âë�ðåéò ôçí �åöáë� ôçò â�äáò.

Óùóôü �áé áõôü ���ï!
Thanks, èá ôï �ïéô�îïõìå íá äïýìå ðùò ìðïñå� íá äïõë�øåé - áëë� íïì�æïõìå üôé èá ÷ñåéáóôå� íá å�íáé õðü ãùí�á... (ïé �ýëéíäñïé å�íáé ì�ó'ôç ì�óç..)

[hpergm]

Γ�éá ìéΓ�Γ±Γ� äïΓ�éìΓ� ôçò áñ÷éΓ�Γ�Γ²  éäΓ�áò ìáò. Γ�Γ�ëëïí äåΓ�÷íåé Γ�Γ�.

��ñáìå îýëéíï ðç÷��é 10x10mm, îåôñõð�óáìå 6mm �áé �ïëë�óáìå ì�óá áëïõìéí�íéï óùë�íá (áðü Leroy Merlin). �åô� áíï�îáìå óðå�ñùìá 3mm ãéá ôç â�äá áóö�ëéóçò. Ç ìåã�ëç â�äá å�íáé 4mm �áé èá ðåñáóôå� óôï ìðñïóôéíü ìðïõëì� ôçò ó�ëëáò.

Ôá îýëéíá ìðëü� èá �ïëëçèïýí ìåô� �áôåõèå�áí óôï cowl �áé ôï cowl ring.

[dgiatr]

.............ð�ëé �áë� ðïõ å�íáé �áé áõô� ôá warbirds �áé ðá�ñíïõìå ë�ãï ì�ôé ãéá íá åõöñáéíüìáóôå óôïõò äýó�ïëïõò �áéñïýò ðïõ æïýìå....
Γ�ðñΓ�ΓΆΓ―  ΒΈΓ�ôïñá Γ§ Γ―Γ¬Γ�äá "Γ³Γ�ïôþíåé"! 

[hpergm]

�áé... ö�ñìá�ï. Ôïõë�÷éóôïí áõô� äå.... öïñïëïãïýíôáé óáí å�äç ðïëõôåëå�áò (��ðïôå, ôï '80;!

��ìå ðáñá��ôù. Ôïðïèåô�èç�áí ôá custom ��ôù ìðëü� ôïõ cowl áöüôïõ åõèõãñáìì�óôç�áí ìå ôéò ôñýðåò ðïõ å�÷áìå �äç áíï�îåé óôï cowl ring �áé ôï ð�óù former. Éäéá�ôåñç ðñïóï÷� äüèç�å óôïí �áèáñéóìü ôçò ãýñù åðéö�íåéáò ìå ãõáëü÷áñôï �áé áóåôüí, �áèþò �áé "ôñõðï...�áñýäùìá" ìå pin óôéò åðéö�íåéåò ôùí îýëùí ãéá íá ðïô�óåé �áë� ç �üëëá.

�åô� ä�èç�å ç üëç �áôáó�åõ� ìå ðñïóùñéí�ò â�äåò �áé ðáîéì�äéá ãéá íá óôåãíþóåé ç epoxy 2 ùñþí. �é ôåëé��ò â�äåò èá å�íáé �ïíôýôåñåò �áé èá �ïëëçèïýí ìå ôç óåéñ� ôïõò óôï ìðñïóôéíü former ôçò ó�ëëáò. Ãéá íá ì� ã�íåé �áí�íá... áôý÷çìá, öñïíô�óáìå íá åðáëå�øïõìå ôá óðåéñþìáôá �áé ôï åóùôåñé�ü ôùí ìåôáëëé�þí óùë�íùí ìå âáæåë�íç äéüôé ç �üëëá ìðïñå� íá ðéåóôå� ì�óá óôá äé��åíá.

Γ�áé Γ­Γ΅Γ�, ôá ìðëüΓ� Γ¥Γ�íáé Γ�ïëëçìΓ�Γ­Γ΅ Γ«Γ�ãï óôñáâΓ�, äéüôé áðïõóΓ�Γ΅ Γ�ïëùíïäñΓ�ðáíïõ, Γ―Γ© ôñýðåò ãéá ôá óùëçíΓ�Γ�éá äå ìáò ΓΆΓ£Γ�Γ�áí Γ�óéåò  .
�ëë� óçìáíôé�ü å�íáé ôá óùëçí��éá (�áé ü÷é ôá ðç÷��éá) íá å�íáé ðáñ�ëëçëá ãéá íá âãá�íåé åý�ïëá - ïðüôå �áé öá�íåôáé ç óôñáâùì�ñá.
(Äå ãïõóô� - áëë� ôé íá ��;)

[MOGOLOS]

Γ§ ôå÷íç ôïõ ÷åéñïðïΓ�çôïõ 

[hpergm]

Ôåëåéþóáìå �áé ôï "ôåë�ñùìá" ôçò â�óçò (åðéô�ëïõò..). ×ñçóéìïðïé�óáìå áëïõìéí�íéá ãùí�á/ðñïö�ë áðü ôï Leroy Merlin. Ë�ãï á�ñéâü óôá €12 ôï �ïìì�ôé, áëë� ôïõë�÷éóôïí âñ��áìå �ïìì�ôéá >1.5ì ãéá íá ��íïõìå ôç äïõëåé�.

Ôï áðïô�ëåóìá å�íáé ��áìðôï �áé åëáöñý. ×ñçóéìïðïé�èç�å áôëá�üë �ñõóôáëëé��, áöüôïõ áãñéåýôç�áí ïé åðéö�íåéåò ôùí áëïõìéí�ùí (áíïä�ùóç) ãéá íá ðé�óåé �áë� ç �üëëá.

[hpergm]

�ñï÷ùñ�ìå ìå ôá ôåëåéþìáôá ôùí â�óåùí ôïõ cowl. Öôé�îáìå í�åò â�óåéò ãéá ôéò åð�íù óôçñ�îåéò �üâïíôáò áðü ôá ðåñéóóåýìáôá ôïõ ðñïö�ë ãùíé�ò áëïõìéí�ïõ.
�õô� ìåô� ôñï÷�óôç�áí óôï ðñïö�ë ôïõ cowl �áé âéäþèç�áí óôçí �ôñá�ôï, ��ôù áðü ôï åý�ïëá áöáéñïýìåíï gun hood, ìå ôç âï�èåéá blind nuts ôùí 3mm. Ãéá íá"äáã�þóïõí" áõô� �áë� �áé óå é�áíü ð�÷ïò, ôïðïèåô�èç�áí åíéó÷ýóåéò áðü ply 3mm åíôüò ôçò áôñ��ôïõ.

[hpergm]

�áé áðü ��ôù/ì�óá...
��ñïò ôïõ cowl ring óôá ðë�ãéá �üðç�å ãéá íá áíïé÷èïýí áåñáãùãï� (ðñïóå÷þò).

[hpergm]

¢íïéãìá ðëáúíþí áåñáãùãþí.

- �ñþôá �íá rough cut ìå dremel �áé "�ãñéï" óâïõñ��é ãéá ó��ëéóìá ìåô�ëëïõ.
- �åô�, �áè�ñéóìá ìå ìåã�ëï �áé ìé�ñü óâïõñ��é ãõáëü÷áñôïõ.
- ¢íïéãìá �ëåéóôþí äéá�ïóìçôé�þí åîáôì�óåùí �áé ôùí "gills" åîáåñéóìïý ìå óâïõñ��é ÷áñá�ôé��ò (ðïëý ìõôåñü �áé ëåðôü). �åô� �áè�ñéóìá ìå óâïõñ��é ó�áë�óìáôïò ìåô�ëëïõ (ëéãüôåñï �ãñéï ãéá íá ìçí "ðçä�åé").
- Ô�ëïò, áðï�áô�óôáóç "óðáóéì�ôùí" ôïõ gelcoat/paint-chipping �áé ÷�ñé ð�ñáóìá ìå áåñïãñ�öï (matt black) ãéá íá îáíáäå�îåé ïìïéïãåí�ò.

Óôá ôåëåéþìáôá èá ðåñáóôïýí Γ―Γ© åîáôìΓ�óåéò ìå ôçí áíΓ�ëïãç öèïñΓ�/Γ�áðíéΓ�/ðáëáΓ�ΓΉΓ³Γ§ - Γ�Γ­ Γ�áé Γ�áëýðôïíôáé áðü ôï cowl. Γ“Γ�åöôüìáóôå Γ­Γ΅ ÷ñçóéìïðïéΓ�óïõìå ôá îçñΓ� ðáóôΓ�Γ« Γ�áé ìáëáΓ�ΓΌ ðéíΓ�ëï. (Γ�íïé÷ôïΓ�, ΓΆΓ�âáéá, Γ³Γ¥ ðñïôΓ�óåéò Γ�áé áðü ôïõò ðéü Γ�ìðåéñïõò...  )

[hpergm]

Ôá åñãáëå�á ðåñ� ùí ï ëüãïò..

[hpergm]

Cowl-on..

(Ç áíáã�áéüôçôá �ïð�ò ôïõ cowl ring å�íáé ôþñá ðñïöáí�ò..)

Γ‡ åðéöΓ�íåéá åîüäïõ ôþñá õðïëïãΓ�æåôáé Γ³Γ¥ 2,320mm² (Γ�áé Γ―Γ© äõï ðëåõñΓ�Γ²).
Γ‡ åðéöΓ�íåéá åéóüäïõ ìå ôï baffle õðïëïãΓ�æåôáé Γ³Γ¥ 3,548mm² (ðåñΓ�ãñáììá baffle x ~4mm äéΓ�Γ�åíï ìåôáîý ìç÷áíΓ�Γ² Γ�áé baffle ãýñù-ãýñù).

Ãéá Γ­Γ΅ ðåôý÷ïõìå áíáëïãΓ�Γ΅ >1:1 (ôïõëΓ�÷éóôïí...), ðñΓ�ðåé Γ­Γ΅ âñïýìå Γ�ëëá 3,548 - 2,320 = 1,228mm².

�á ðñ�ðåé äçë. íá ôïðïèåôçèïýí �áé ãñ�ëëéåò óôï cowl. Ç åðéö�íåéá åîüäïõ áõôþí õðïëïã�æåôáé óå 1,280 áí� ãñ�ëéá.
ΒΆΓ±Γ΅, ìå 2 ôåìΓ�÷éá Γ¥Γ�áôΓ�ñùèåí ôçò åîΓ�ôìéóçò èá Γ°Γ�ñïõìå ìéá áíáëïãΓ�Γ΅ ~1: 1.4. ΒΌΓ·Γ© éäéáΓ�ôåñá åíèïõóéþäç...  
(Ãé'áõôü �áé ðñïóðáè�óáìå ðïëý íá öôé�îïõìå ðïëý "áã�áëéáóôü" baffle...)

[Demetre]

Dear friend,i see that you have been spending a grate deal of time and thinking on this model (beside money).
Without getting too technical i would like to point out a few thinks that will help you with the engine cooling  of your project,
   The sq.cm relation, of inlet-outlet 1 : 3 e.t.c. on scale models, you will find that it is very hard to meet.
This is one of the reasons that we add or remove  parts,like engine buffles, at the static display of a scale model,and remove them before flight.
 There is a litlle Diavolos called[ Raynold's Number] that is messing-up all those calculations,and on top of that[Heat Drag] , and Turbulence,inside the cowling,that we have to deal with.
VALUME of MOVING AIR (Exchanged air through the cowling) rather,is what  we are looking for.
In order to achive that,beside the size of the opennings, think like .....smooth transition of air mass ,from one area to the next, minimize the obstacls(structural members),turns,choks,e.t.c.
HEAT VENTS work great as long they are constructed properly (NO ruff edges, Bernoullis Law and"VENTURI " system) when you make an air intake or outlet(use some putty or caulking materials and a litlle imagination ,(epoxy mixed with microballons or Baking Soda for weight reduction works good here).
And last but not least ,we don't have the sufficient equipment to take measurements, no wind tunnels available,in our neiborhood.
Personally i have been using Stage smoker (old Rock'n Roller) with exellent resaults.A smokey fire and a shop vacuum,if available,works great.(suck and blow).
Happy flying. Jim

[hpergm]

Dear Dim,

Thanks for taking the time to give detailed feedback. Yes, I have also been expecting a tough inlet/outlet ratio on a scale warbird - thus the effort for a close-fitting baffle. With a 3-cylinder 4-stroke gasser, the heat accumulation in the cowl will be more than aything I have experienced and I am also a bit worried about it (read: extended head-scratching).

After fitting the outlet vents/gills on the bottom of the cowl, that will be it as far as "mild" surgical options are concerned. I may also think about passaging the flow inside; in fact I will add guides to "hug" the cylinders on the backside of the baffle (will be presented shortly).

If heat still proves a problem, I will have to think something more radical. The cooling fan option still exists, but requires a lot of machine work which I am not ready to commit to yet, in case the simple "vaccum" set-up works OK. And it has worked OK for other people who even use a larger engine (FG-84) but still do not baffle it..!

What I will do is to install telemetry for temperatures and rpm, so I will be able to check engine condition in-flight and possibly avoid a nasty surprise (i.e. some feedback to allow me to "fly the engine"). And even then, I may use the telemetry data to... actively control engine cooling! (How? Stay tuned to this thread...)